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Hall SB, Zuo YY. The biophysical function of pulmonary surfactant. Biophys J 2024; 123:1519-1530. [PMID: 38664968 PMCID: PMC11213971 DOI: 10.1016/j.bpj.2024.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Revised: 04/08/2024] [Accepted: 04/22/2024] [Indexed: 05/12/2024] Open
Abstract
The type II pneumocytes of the lungs secrete a mixture of lipids and proteins that together acts as a surfactant. The material forms a thin film on the surface of the liquid layer that lines the alveolar air sacks. When compressed by the decreasing alveolar surface area during exhalation, the films reduce surface tension to exceptionally low levels. Pulmonary surfactant is essential for preserving the integrity of the barrier between alveolar air and capillary blood during normal breathing. This review focuses on the major biophysical processes by which endogenous pulmonary surfactant achieves its function and the mechanisms involved in those processes. Vesicles of pulmonary surfactant adsorb rapidly from the alveolar liquid to form the interfacial film. Interfacial insertion, which requires the hydrophobic surfactant protein SP-B, proceeds by a process analogous to the fusion of two vesicles. When compressed, the adsorbed film desorbs slowly. Constituents remain at the surface at high interfacial concentrations that reduce surface tensions well below equilibrium levels. We review the models proposed to explain how pulmonary surfactant achieves both the rapid adsorption and slow desorption characteristic of a functional film.
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Affiliation(s)
- Stephen B Hall
- Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon.
| | - Yi Y Zuo
- Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii
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2
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He S, Chen Z, Xue C, Zhou L, Li C, Jiang W, Lian S, Shen Y, Liao M, Zhang X. MiR-9a-5p alleviates ventilator-induced lung injury in rats by inhibiting the activation of the MAPK signaling pathway via CXCR4 expression downregulation. Int Immunopharmacol 2022; 112:109288. [DOI: 10.1016/j.intimp.2022.109288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 09/15/2022] [Accepted: 09/23/2022] [Indexed: 11/05/2022]
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3
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Yueyi J, Jing T, Lianbing G. A structured narrative review of clinical and experimental studies of the use of different positive end-expiratory pressure levels during thoracic surgery. THE CLINICAL RESPIRATORY JOURNAL 2022; 16:717-731. [PMID: 36181340 PMCID: PMC9629996 DOI: 10.1111/crj.13545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 09/03/2022] [Accepted: 09/12/2022] [Indexed: 01/25/2023]
Abstract
OBJECTIVES This study aimed to present a review on the general effects of different positive end-expiratory pressure (PEEP) levels during thoracic surgery by qualitatively categorizing the effects into detrimental, beneficial, and inconclusive. DATA SOURCE Literature search of Pubmed, CNKI, and Wanfang was made to find relative articles about PEEP levels during thoracic surgery. We used the following keywords as one-lung ventilation, PEEP, and thoracic surgery. RESULTS We divide the non-individualized PEEP value into five grades, that is, less than 5, 5, 5-10, 10, and more than 10 cmH2 O, among which 5 cmH2 O is the most commonly used in clinic at present to maintain alveolar dilatation and reduce the shunt fraction and the occurrence of atelectasis, whereas individualized PEEP, adjusted by test titration or imaging method to adapt to patients' personal characteristics, can effectively ameliorate intraoperative oxygenation and obtain optimal pulmonary compliance and better indexes relating to respiratory mechanics. CONCLUSIONS Available data suggest that PEEP might play an important role in one-lung ventilation, the understanding of which will help in exploring a simple and economical method to set the appropriate PEEP level.
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Affiliation(s)
- Jiang Yueyi
- The Affiliated Cancer Hospital of Nanjing Medical UniversityNanjingChina
| | - Tan Jing
- Department of AnesthesiologyJiangsu Cancer HospitalNanjingChina
| | - Gu Lianbing
- The Affiliated Cancer Hospital of Nanjing Medical UniversityNanjingChina,Department of AnesthesiologyJiangsu Cancer HospitalNanjingChina
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4
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Zeng C, Lagier D, Lee JW, Melo MFV. Perioperative Pulmonary Atelectasis: Part I. Biology and Mechanisms. Anesthesiology 2022; 136:181-205. [PMID: 34499087 PMCID: PMC9869183 DOI: 10.1097/aln.0000000000003943] [Citation(s) in RCA: 50] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Pulmonary atelectasis is common in the perioperative period. Physiologically, it is produced when collapsing forces derived from positive pleural pressure and surface tension overcome expanding forces from alveolar pressure and parenchymal tethering. Atelectasis impairs blood oxygenation and reduces lung compliance. It is increasingly recognized that it can also induce local tissue biologic responses, such as inflammation, local immune dysfunction, and damage of the alveolar-capillary barrier, with potential loss of lung fluid clearance, increased lung protein permeability, and susceptibility to infection, factors that can initiate or exaggerate lung injury. Mechanical ventilation of a heterogeneously aerated lung (e.g., in the presence of atelectatic lung tissue) involves biomechanical processes that may precipitate further lung damage: concentration of mechanical forces, propagation of gas-liquid interfaces, and remote overdistension. Knowledge of such pathophysiologic mechanisms of atelectasis and their consequences in the healthy and diseased lung should guide optimal clinical management.
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Affiliation(s)
- Congli Zeng
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - David Lagier
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Jae-Woo Lee
- Department of Anesthesia, University of California San Francisco, San Francisco, CA, USA
| | - Marcos F. Vidal Melo
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
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5
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Abstract
Mechanical ventilation can be life-saving for the premature infant, but is often injurious to immature and underdeveloped lungs. Lung injury is caused by atelectrauma, oxygen toxicity, and volutrauma. Lung protection must include appropriate lung recruitment starting in the delivery suite and throughout mechanical ventilation. Strategies include open lung ventilation, positive end-expiratory pressure, and volume-targeted ventilation. Respiratory function monitoring, such as capnography and ventilator graphics, provides clinicians with continuous real-time information and an adjunct to optimize lung-protective ventilatory strategies. Further research is needed to assess which lung-protective strategies result in a decrease in long-term respiratory morbidity.
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6
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Thomson J, Rüegger CM, Perkins EJ, Pereira-Fantini PM, Farrell O, Owen LS, Tingay DG. Regional ventilation characteristics during non-invasive respiratory support in preterm infants. Arch Dis Child Fetal Neonatal Ed 2021; 106:370-375. [PMID: 33246967 DOI: 10.1136/archdischild-2020-320449] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 10/14/2020] [Accepted: 11/03/2020] [Indexed: 01/04/2023]
Abstract
OBJECTIVES To determine the regional ventilation characteristics during non-invasive ventilation (NIV) in stable preterm infants. The secondary aim was to explore the relationship between indicators of ventilation homogeneity and other clinical measures of respiratory status. DESIGN Prospective observational study. SETTING Two tertiary neonatal intensive care units. PATIENTS Forty stable preterm infants born <30 weeks of gestation receiving either continuous positive airway pressure (n=32) or high-flow nasal cannulae (n=8) at least 24 hours after extubation at time of study. INTERVENTIONS Continuous electrical impedance tomography imaging of regional ventilation during 60 min of quiet breathing on clinician-determined non-invasive settings. MAIN OUTCOME MEASURES Gravity-dependent and right-left centre of ventilation (CoV), percentage of whole lung tidal volume (VT) by lung region and percentage of lung unventilated were determined for 120 artefact-free breaths/infant (4770 breaths included). Oxygen saturation, heart and respiratory rates were also measured. RESULTS Ventilation was greater in the right lung (mean 69.1 (SD 14.9)%) total VT and the gravity-non-dependent (ND) lung; ideal-actual CoV 1.4 (4.5)%. The central third of the lung received the most VT, followed by the non-dependent and dependent regions (p<0.0001 repeated-measure analysis of variance). Ventilation inhomogeneity was associated with worse peripheral capillary oxygen saturation (SpO2)/fraction of inspired oxygen (FiO2) (p=0.031, r2 0.12; linear regression). In those infants that later developed bronchopulmonary dysplasia (n=25), SpO2/FiO2 was worse and non-dependent ventilation inhomogeneity was greater than in those that did not (both p<0.05, t-test Welch correction). CONCLUSIONS There is high breath-by-breath variability in regional ventilation patterns during NIV in preterm infants. Ventilation favoured the ND lung, with ventilation inhomogeneity associated with worse oxygenation.
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Affiliation(s)
- Jessica Thomson
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia .,Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Christoph M Rüegger
- Newborn Research, The Royal Women's Hospital, Parkville, Victoria, Australia.,Newborn Research, Department of Neonatology, University Hospital and University of Zürich, Zürich, Switzerland
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | | | - Olivia Farrell
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Paediatrics, University of Melbourne, Parkville, Victoria, Australia
| | - Louise S Owen
- Newborn Research, The Royal Women's Hospital, Parkville, Victoria, Australia
| | - David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatology, The Royal Children's Hospital Melbourne, Parkville, Victoria, Australia
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7
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Cylwik J, Buda N. Lung Ultrasonography in the Monitoring of Intraoperative Recruitment Maneuvers. Diagnostics (Basel) 2021; 11:diagnostics11020276. [PMID: 33578960 PMCID: PMC7916700 DOI: 10.3390/diagnostics11020276] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/06/2021] [Accepted: 02/08/2021] [Indexed: 11/22/2022] Open
Abstract
Introduction: Postoperative respiratory failure is a serious problem in patients who undergo general anesthesia. Approximately 90% of mechanically ventilated patients during the surgery may develop atelectasis that leads to perioperative complications. Aim: The aim of this study is to determine whether it is possible to optimize recruitment maneuvers with the use of chest ultrasonography, thus limiting the risk of respiratory complications in patients who undergo general anesthesia. Methodology: The method of incremental increases in positive end-expiratory pressure (PEEP) values with simultaneous continuous ultrasound assessments was employed in mechanically ventilated patients. Results: The study group comprised 100 patients. The employed method allowed for atelectasis reduction in 91.9% of patients. The PEEP necessary to reverse areas of atelectasis averaged 17cmH2O, with an average peak pressure of 29cmH2O. The average PEEP that prevented repeat atelectasis was 9cmH2O. A significant improvement in lung compliance and saturation was obtained. Conclusions: Ultrasound-guided recruitment maneuvers facilitate the patient-based adjustment of the process. Consequently, the reduction in ventilation pressures necessary to aerate intraoperative atelectasis is possible, with the simultaneous reduction in the risk of procedure-related complications.
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Affiliation(s)
- Jolanta Cylwik
- Anesthesiology and Intensive Care Unit, Mazovia Regional Hospital, 08-110 Siedlce, Poland;
| | - Natalia Buda
- Department of Internal Medicine, Connective Tissue Diseases and Geriatrics, Medical University of Gdansk, 80-210 Gdańsk, Poland
- Correspondence:
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Fiedler MO, Simeliunas E, Deutsch BL, Diktanaite D, Harms A, Brune M, Dietrich M, Uhle F, Weigand MA, Kalenka A. Impact of Different Positive End-Expiratory Pressures on Lung Mechanics in the Setting of Moderately Elevated Intra-Abdominal Pressure and Acute Lung Injury in a Porcine Model. J Clin Med 2021; 10:306. [PMID: 33467666 PMCID: PMC7830768 DOI: 10.3390/jcm10020306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 01/10/2021] [Accepted: 01/12/2021] [Indexed: 12/27/2022] Open
Abstract
The effects of a moderately elevated intra-abdominal pressure (IAP) on lung mechanics in acute respiratory distress syndrome (ARDS) have still not been fully analyzed. Moreover, the optimal positive end-expiratory pressure (PEEP) in elevated IAP and ARDS is unclear. In this paper, 18 pigs under general anesthesia received a double hit lung injury. After saline lung lavage and 2 h of injurious mechanical ventilation to induce an acute lung injury (ALI), an intra-abdominal balloon was filled until an IAP of 10 mmHg was generated. Animals were randomly assigned to one of three groups (group A = PEEP 5, B = PEEP 10 and C = PEEP 15 cmH2O) and ventilated for 6 h. We measured end-expiratory lung volume (EELV) per kg bodyweight, driving pressure (ΔP), transpulmonary pressure (ΔPL), static lung compliance (Cstat), oxygenation (P/F ratio) and cardiac index (CI). In group A, we found increases in ΔP (22 ± 1 vs. 28 ± 2 cmH2O; p = 0.006) and ΔPL (16 ± 1 vs. 22 ± 2 cmH2O; p = 0.007), with no change in EELV/kg (15 ± 1 vs. 14 ± 1 mL/kg) when comparing hours 0 and 6. In group B, there was no change in ΔP (26 ± 2 vs. 25 ± 2 cmH2O), ΔPL (19 ± 2 vs. 18 ± 2 cmH2O), Cstat (21 ± 3 vs. 21 ± 2 cmH2O/mL) or EELV/kg (12 ± 2 vs. 13 ± 3 mL/kg). ΔP and ΔPL were significantly lower after 6 h when comparing between group C and A (21 ± 1 vs. 28 ± 2 cmH2O; p = 0.020) and (14 ± 1 vs. 22 ± 2 cmH2O; p = 0.013)). The EELV/kg increased over time in group C (13 ± 1 vs. 19 ± 2 mL/kg; p = 0.034). The P/F ratio increased in all groups over time. CI decreased in groups B and C. The global lung injury score did not significantly differ between groups (A: 0.25 ± 0.05, B: 0.21 ± 0.02, C: 0.22 ± 0.03). In this model of ALI, elevated IAP, ΔP and ΔPL increased further over time in the group with a PEEP of 5 cmH2O applied over 6 h. This was not the case in the groups with a PEEP of 10 and 15 cmH2O. Although ΔP and ΔPL were significantly lower after 6 hours in group C compared to group A, we could not show significant differences in histological lung injury score.
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Affiliation(s)
- Mascha O. Fiedler
- Department of Anesthesiology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (E.S.); (D.D.); (M.D.); (F.U.); (M.A.W.)
- Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), 69120 Heidelberg, Germany;
| | - Emilis Simeliunas
- Department of Anesthesiology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (E.S.); (D.D.); (M.D.); (F.U.); (M.A.W.)
- Department of Anesthesiology, Kantonsspital Lucerne, 6004 Lucerne, Switzerland
| | - B. Luise Deutsch
- Faculty of Medicine, Justus Liebig University, 35392 Giessen, Germany;
| | - Dovile Diktanaite
- Department of Anesthesiology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (E.S.); (D.D.); (M.D.); (F.U.); (M.A.W.)
- Department of Anesthesiology, Kantonsspital Lucerne, 6004 Lucerne, Switzerland
| | - Alexander Harms
- Institute of Pathology, University Hospital Heidelberg, 69120 Heidelberg, Germany;
| | - Maik Brune
- Department of Internal Medicine I and Clinical Chemistry, University Hospital Heidelberg, 69120 Heidelberg, Germany;
| | - Maximilian Dietrich
- Department of Anesthesiology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (E.S.); (D.D.); (M.D.); (F.U.); (M.A.W.)
| | - Florian Uhle
- Department of Anesthesiology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (E.S.); (D.D.); (M.D.); (F.U.); (M.A.W.)
| | - Markus A. Weigand
- Department of Anesthesiology, Heidelberg University Hospital, 69120 Heidelberg, Germany; (E.S.); (D.D.); (M.D.); (F.U.); (M.A.W.)
- Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), 69120 Heidelberg, Germany;
| | - Armin Kalenka
- Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), 69120 Heidelberg, Germany;
- Department of Anesthesiology and Intensive Care Medicine, Hospital Bergstrasse, 64646 Heppenheim, Germany
- Faculty of Medicine, University of Heidelberg, 69120 Heidelberg, Germany
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Synchronized Inflations Generate Greater Gravity-Dependent Lung Ventilation in Neonates. J Pediatr 2021; 228:24-30.e10. [PMID: 32827530 DOI: 10.1016/j.jpeds.2020.08.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/05/2020] [Accepted: 08/14/2020] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To describe the regional distribution patterns of tidal ventilation within the lung during mechanical ventilation that is synchronous or asynchronous with an infant's own breathing effort. STUDY DESIGN Intubated infants receiving synchronized mechanical ventilation at The Royal Children's Hospital neonatal intensive care unit were studied. During four 10-minute periods of routine care, regional distribution of tidal volume (VT; electrical impedance tomography), delivered pressure, and airway flow (Florian Respiratory Monitor) were measured for every inflation. Post hoc, each inflation was then classified as synchronous or asynchronous from video data of the ventilator screen, and the distribution of absolute VT and delivered ventilation characteristics determined. RESULTS In total, 2749 inflations (2462 synchronous) were analyzed in 19 infants; mean (SD) age 28 (30) days, gestational age 35 (5) weeks. Synchronous inflations were associated with a shorter respiratory cycle (P = .004) and more homogenous VT (center of ventilation) along the right (0%) to left (100%) lung plane; 45.3 (8.6)% vs 48.8 (9.4)% (uniform ventilation 46%). The gravity-dependent center of ventilation was a mean (95% CI) 2.1 (-0.5, 4.6)% toward the dependent lung during synchronous inflations. Tidal ventilation relative to anatomical lung size was more homogenous during synchronized inflations in the dependent lung. CONCLUSIONS Synchronous mechanical ventilator lung inflations generate more gravity-dependent lung ventilation and more uniform right-to-left ventilation than asynchronous inflations.
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10
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Low-Cost, Open-Source Mechanical Ventilator with Pulmonary Monitoring for COVID-19 Patients. ACTUATORS 2020. [DOI: 10.3390/act9030084] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This paper shows the construction of a low-cost, open-source mechanical ventilator. The motivation for constructing this kind of ventilator comes from the worldwide shortage of mechanical ventilators for treating COVID-19 patients—the COVID-19 pandemic has been striking hard in some regions, especially the deprived ones. Constructing a low-cost, open-source mechanical ventilator aims to mitigate the effects of this shortage on those regions. The equipment documented here employs commercial spare parts only. This paper also shows a numerical method for monitoring the patients’ pulmonary condition. The method considers pressure measurements from the inspiratory limb and alerts clinicians in real-time whether the patient is under a healthy or unhealthy situation. Experiments carried out in the laboratory that had emulated healthy and unhealthy patients illustrate the potential benefits of the derived mechanical ventilator.
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11
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Prospective Observational Study to Evaluate the Effect of Different Levels of Positive End-Expiratory Pressure on Lung Mechanics in Patients with and without Acute Respiratory Distress Syndrome. J Clin Med 2020; 9:jcm9082446. [PMID: 32751791 PMCID: PMC7463691 DOI: 10.3390/jcm9082446] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/27/2020] [Accepted: 07/28/2020] [Indexed: 12/12/2022] Open
Abstract
Background: The optimal level of positive end-expiratory pressure is still under debate. There are scare data examining the association of PEEP with transpulmonary pressure (TPP), end-expiratory lung volume (EELV) and intraabdominal pressure in ventilated patients with and without ARDS. Methods: We analyzed lung mechanics in 3 patient groups: group A, patients with ARDS; group B, obese patients (body mass index (BMI) > 30 kg/m2) and group C, a control group. Three levels of PEEP (5, 10, 15 cm H2O) were used to investigate the consequences for lung mechanics. Results: Fifty patients were included, 22 in group A, 18 in group B (BMI 38 ± 2 kg/m2) and 10 in group C. At baseline, oxygenation showed no differences between the groups. Driving pressure (ΔP) and transpulmonary pressure (ΔPL) was higher in group B than in groups A and C at a PEEP of 5 cm H2O (ΔP A: 15 ± 1, B: 18 ± 1, C: 14 ± 1 cm H2O; ΔPL A: 10 ± 1, B: 13 ± 1, C: 9 ± 0 cm H2O). Peak inspiratory pressure (Pinsp) rose in all groups as PEEP increased, but the resulting driving pressure and transpulmonary pressure were reduced, whereas EELV increased. Conclusion: Measuring EELV or TPP allows a personalized approach to lung-protective ventilation.
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12
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Abstract
Ventilation-induced lung injury results from mechanical stress and strain that occur during tidal ventilation in the susceptible lung. Classical descriptions of ventilation-induced lung injury have focused on harm from positive pressure ventilation. However, injurious forces also can be generated by patient effort and patient–ventilator interactions. While the role of global mechanics has long been recognized, regional mechanical heterogeneity within the lungs also appears to be an important factor propagating clinically significant lung injury. The resulting clinical phenotype includes worsening lung injury and a systemic inflammatory response that drives extrapulmonary organ failures. Bedside recognition of ventilation-induced lung injury requires a high degree of clinical acuity given its indistinct presentation and lack of definitive diagnostics. Yet the clinical importance of ventilation-induced lung injury is clear. Preventing such biophysical injury remains the most effective management strategy to decrease morbidity and mortality in patients with acute respiratory distress syndrome and likely benefits others at risk.
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Affiliation(s)
- Purnema Madahar
- Center for Acute Respiratory Failure, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Department of Medicine, New York-Presbyterian Hospital, New York City, NY, USA
| | - Jeremy R Beitler
- Center for Acute Respiratory Failure, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians and Surgeons, New York City, NY, USA.,Department of Medicine, New York-Presbyterian Hospital, New York City, NY, USA
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13
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Tingay DG, Pereira-Fantini PM, Oakley R, McCall KE, Perkins EJ, Miedema M, Sourial M, Thomson J, Waldmann A, Dellaca RL, Davis PG, Dargaville PA. Gradual Aeration at Birth Is More Lung Protective Than a Sustained Inflation in Preterm Lambs. Am J Respir Crit Care Med 2020; 200:608-616. [PMID: 30730759 DOI: 10.1164/rccm.201807-1397oc] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Rationale: The preterm lung is susceptible to injury during transition to air breathing at birth. It remains unclear whether rapid or gradual lung aeration at birth causes less lung injury.Objectives: To examine the effect of gradual and rapid aeration at birth on: 1) the spatiotemporal volume conditions of the lung; and 2) resultant regional lung injury.Methods: Preterm lambs (125 ± 1 d gestation) were randomized at birth to receive: 1) tidal ventilation without an intentional recruitment (no-recruitment maneuver [No-RM]; n = 19); 2) sustained inflation (SI) until full aeration (n = 26); or 3) tidal ventilation with an initial escalating/de-escalating (dynamic) positive end-expiratory pressure (DynPEEP; n = 26). Ventilation thereafter continued for 90 minutes at standardized settings, including PEEP of 8 cm H2O. Lung mechanics and regional aeration and ventilation (electrical impedance tomography) were measured throughout and correlated with histological and gene markers of early lung injury.Measurements and Main Results: DynPEEP significantly improved dynamic compliance (P < 0.0001). An SI, but not DynPEEP or No-RM, resulted in preferential nondependent lung aeration that became less uniform with time (P = 0.0006). The nondependent lung was preferential ventilated by 5 minutes in all groups, with ventilation only becoming uniform with time in the No-RM and DynPEEP groups. All strategies generated similar nondependent lung injury patterns. Only an SI caused greater upregulation of dependent lung gene markers compared with unventilated fetal controls (P < 0.05).Conclusions: Rapidly aerating the preterm lung at birth creates heterogeneous volume states, producing distinct regional injury patterns that affect subsequent tidal ventilation. Gradual aeration with tidal ventilation and PEEP produced the least lung injury.
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Affiliation(s)
- David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatology, The Royal Children's Hospital, Parkville, Victoria, Australia.,Neonatal Research, The Royal Women's Hospital, Parkville, Victoria, Australia.,Department of Paediatrics and
| | - Prue M Pereira-Fantini
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Department of Paediatrics and
| | - Regina Oakley
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Karen E McCall
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Elizabeth J Perkins
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatology, The Royal Children's Hospital, Parkville, Victoria, Australia
| | - Martijn Miedema
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatology, Amsterdam University Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
| | - Magdy Sourial
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | - Jessica Thomson
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia
| | | | - Raffaele L Dellaca
- Dipartimento di Elettronica, Informazione e Ingegneria Biomedica, Politecnico di Milano University, Milan, Italy
| | - Peter G Davis
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatal Research, The Royal Women's Hospital, Parkville, Victoria, Australia.,Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Victoria, Australia
| | - Peter A Dargaville
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Victoria, Australia.,Neonatal and Paediatric Intensive Care Unit, Royal Hobart Hospital, Hobart, Tasmania, Australia; and.,Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania, Australia
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14
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Multimodal non-invasive monitoring to apply an open lung approach strategy in morbidly obese patients during bariatric surgery. J Clin Monit Comput 2019; 34:1015-1024. [PMID: 31654282 DOI: 10.1007/s10877-019-00405-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 10/14/2019] [Indexed: 01/20/2023]
Abstract
To evaluate the use of non-invasive variables for monitoring an open-lung approach (OLA) strategy in bariatric surgery. Twelve morbidly obese patients undergoing bariatric surgery received a baseline protective ventilation with 8 cmH2O of positive-end expiratory pressure (PEEP). Then, the OLA strategy was applied consisting in lung recruitment followed by a decremental PEEP trial, from 20 to 8 cmH2O, in steps of 2 cmH2O to find the lung's closing pressure. Baseline ventilation was then resumed setting open lung PEEP (OL-PEEP) at 2 cmH2O above this pressure. The multimodal non-invasive variables used for monitoring OLA consisted in pulse oximetry (SpO2), respiratory compliance (Crs), end-expiratory lung volume measured by a capnodynamic method (EELVCO2), and esophageal manometry. OL-PEEP was detected at 15.9 ± 1.7 cmH2O corresponding to a positive end-expiratory transpulmonary pressure (PL,ee) of 0.9 ± 1.1 cmH2O. ROC analysis showed that SpO2 was more accurate (AUC 0.92, IC95% 0.87-0.97) than Crs (AUC 0.76, IC95% 0.87-0.97) and EELVCO2 (AUC 0.73, IC95% 0.64-0.82) to detect the lung's closing pressure according to the change of PL,ee from positive to negative values. Compared to baseline ventilation with 8 cmH2O of PEEP, OLA increased EELVCO2 (1309 ± 517 vs. 2177 ± 679 mL) and decreased driving pressure (18.3 ± 2.2 vs. 10.1 ± 1.7 cmH2O), estimated shunt (17.7 ± 3.4 vs. 4.2 ± 1.4%), lung strain (0.39 ± 0.07 vs. 0.22 ± 0.06) and lung elastance (28.4 ± 5.8 vs. 15.3 ± 4.3 cmH2O/L), respectively; all p < 0.0001. The OLA strategy can be monitored using noninvasive variables during bariatric surgery. This strategy decreased lung strain, elastance and driving pressure compared with standard protective ventilatory settings.Clinical trial number NTC03694665.
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Beitler JR, Sarge T, Banner-Goodspeed VM, Gong MN, Cook D, Novack V, Loring SH, Talmor D. Effect of Titrating Positive End-Expiratory Pressure (PEEP) With an Esophageal Pressure-Guided Strategy vs an Empirical High PEEP-Fio2 Strategy on Death and Days Free From Mechanical Ventilation Among Patients With Acute Respiratory Distress Syndrome: A Randomized Clinical Trial. JAMA 2019; 321:846-857. [PMID: 30776290 PMCID: PMC6439595 DOI: 10.1001/jama.2019.0555] [Citation(s) in RCA: 243] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
IMPORTANCE Adjusting positive end-expiratory pressure (PEEP) to offset pleural pressure might attenuate lung injury and improve patient outcomes in acute respiratory distress syndrome (ARDS). OBJECTIVE To determine whether PEEP titration guided by esophageal pressure (PES), an estimate of pleural pressure, was more effective than empirical high PEEP-fraction of inspired oxygen (Fio2) in moderate to severe ARDS. DESIGN, SETTING, AND PARTICIPANTS Phase 2 randomized clinical trial conducted at 14 hospitals in North America. Two hundred mechanically ventilated patients aged 16 years and older with moderate to severe ARDS (Pao2:Fio2 ≤200 mm Hg) were enrolled between October 31, 2012, and September 14, 2017; long-term follow-up was completed July 30, 2018. INTERVENTIONS Participants were randomized to PES-guided PEEP (n = 102) or empirical high PEEP-Fio2 (n = 98). All participants received low tidal volumes. MAIN OUTCOMES AND MEASURES The primary outcome was a ranked composite score incorporating death and days free from mechanical ventilation among survivors through day 28. Prespecified secondary outcomes included 28-day mortality, days free from mechanical ventilation among survivors, and need for rescue therapy. RESULTS Two hundred patients were enrolled (mean [SD] age, 56 [16] years; 46% female) and completed 28-day follow-up. The primary composite end point was not significantly different between treatment groups (probability of more favorable outcome with PES-guided PEEP: 49.6% [95% CI, 41.7% to 57.5%]; P = .92). At 28 days, 33 of 102 patients (32.4%) assigned to PES-guided PEEP and 30 of 98 patients (30.6%) assigned to empirical PEEP-Fio2 died (risk difference, 1.7% [95% CI, -11.1% to 14.6%]; P = .88). Days free from mechanical ventilation among survivors was not significantly different (median [interquartile range]: 22 [15-24] vs 21 [16.5-24] days; median difference, 0 [95% CI, -1 to 2] days; P = .85). Patients assigned to PES-guided PEEP were significantly less likely to receive rescue therapy (4/102 [3.9%] vs 12/98 [12.2%]; risk difference, -8.3% [95% CI, -15.8% to -0.8%]; P = .04). None of the 7 other prespecified secondary clinical end points were significantly different. Adverse events included gross barotrauma, which occurred in 6 patients with PES-guided PEEP and 5 patients with empirical PEEP-Fio2. CONCLUSIONS AND RELEVANCE Among patients with moderate to severe ARDS, PES-guided PEEP, compared with empirical high PEEP-Fio2, resulted in no significant difference in death and days free from mechanical ventilation. These findings do not support PES-guided PEEP titration in ARDS. TRIAL REGISTRATION ClinicalTrials.gov Identifier NCT01681225.
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Affiliation(s)
- Jeremy R. Beitler
- Center for Acute Respiratory Failure and Division of Pulmonary, Allergy, and Critical Care Medicine, Columbia University College of Physicians & Surgeons, New York, New York
| | - Todd Sarge
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Valerie M. Banner-Goodspeed
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Michelle N. Gong
- Division of Critical Care Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York
| | - Deborah Cook
- Department of Medicine, St Joseph’s Hospital and McMaster University, Hamilton, Ontario, Canada
| | - Victor Novack
- Soroka Clinical Research Center, Soroka University Medical Center, Beer-Sheva, Israel
| | - Stephen H. Loring
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Daniel Talmor
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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Knudsen L, Lopez-Rodriguez E, Berndt L, Steffen L, Ruppert C, Bates JHT, Ochs M, Smith BJ. Alveolar Micromechanics in Bleomycin-induced Lung Injury. Am J Respir Cell Mol Biol 2018; 59:757-769. [PMID: 30095988 PMCID: PMC6293074 DOI: 10.1165/rcmb.2018-0044oc] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 06/29/2018] [Indexed: 12/22/2022] Open
Abstract
Lung injury results in intratidal alveolar recruitment and derecruitment and alveolar collapse, creating stress concentrators that increase strain and aggravate injury. In this work, we sought to describe alveolar micromechanics during mechanical ventilation in bleomycin-induced lung injury and surfactant replacement therapy. Structure and function were assessed in rats 1 day and 3 days after intratracheal bleomycin instillation and after surfactant replacement therapy. Pulmonary system mechanics were measured during ventilation with positive end-expiratory pressures (PEEPs) between 1 and 10 cm H2O, followed by perfusion fixation at end-expiratory pressure at airway opening (Pao) values of 1, 5, 10, and 20 cm H2O for quantitative analyses of lung structure. Lung structure and function were used to parameterize a physiologically based, multicompartment computational model of alveolar micromechanics. In healthy controls, the numbers of open alveoli remained stable in a range of Pao = 1-20 cm H2O, whereas bleomycin-challenged lungs demonstrated progressive alveolar derecruitment with Pao < 10 cm H2O. At Day 3, ∼40% of the alveoli remained closed at high Pao, and alveolar size heterogeneity increased. Simulations of injured lungs predicted that alveolar recruitment pressures were much greater than the derecruitment pressures, so that minimal intratidal recruitment and derecruitment occurred during mechanical ventilation with a tidal volume of 10 ml/kg body weight over a range of PEEPs. However, the simulations also predicted a dramatic increase in alveolar strain with injury that we attribute to alveolar interdependence. These findings suggest that in progressive lung injury, alveolar collapse with increased distension of patent (open) alveoli dominates alveolar micromechanics. PEEP and surfactant substitution reduce alveolar collapse and dynamic strain but increase static strain.
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Affiliation(s)
- Lars Knudsen
- Institute of Functional and Applied Anatomy, and
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover, Member of the German Center for Lung Research (DZL) Hannover Medical School, Hannover, Germany
- REBIRTH, Cluster of Excellence, Hannover, Germany
| | - Elena Lopez-Rodriguez
- Institute of Functional and Applied Anatomy, and
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover, Member of the German Center for Lung Research (DZL) Hannover Medical School, Hannover, Germany
- REBIRTH, Cluster of Excellence, Hannover, Germany
| | | | | | - Clemens Ruppert
- Department of Internal Medicine, and
- Universities of Giessen and Marburg Lung Center, Member of the German Center for Lung Research (DZL), Justus Liebig University Giessen, Giessen, Germany
| | | | - Matthias Ochs
- Institute of Functional and Applied Anatomy, and
- Biomedical Research in Endstage and Obstructive Lung Disease Hannover, Member of the German Center for Lung Research (DZL) Hannover Medical School, Hannover, Germany
- REBIRTH, Cluster of Excellence, Hannover, Germany
| | - Bradford J. Smith
- Department of Bioengineering, University of Colorado Denver, Denver, Colorado
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17
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Knudsen L, Ochs M. The micromechanics of lung alveoli: structure and function of surfactant and tissue components. Histochem Cell Biol 2018; 150:661-676. [PMID: 30390118 PMCID: PMC6267411 DOI: 10.1007/s00418-018-1747-9] [Citation(s) in RCA: 206] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2018] [Indexed: 12/14/2022]
Abstract
The mammalian lung´s structural design is optimized to serve its main function: gas exchange. It takes place in the alveolar region (parenchyma) where air and blood are brought in close proximity over a large surface. Air reaches the alveolar lumen via a conducting airway tree. Blood flows in a capillary network embedded in inter-alveolar septa. The barrier between air and blood consists of a continuous alveolar epithelium (a mosaic of type I and type II alveolar epithelial cells), a continuous capillary endothelium and the connective tissue layer in-between. By virtue of its respiratory movements, the lung has to withstand mechanical challenges throughout life. Alveoli must be protected from over-distension as well as from collapse by inherent stabilizing factors. The mechanical stability of the parenchyma is ensured by two components: a connective tissue fiber network and the surfactant system. The connective tissue fibers form a continuous tensegrity (tension + integrity) backbone consisting of axial, peripheral and septal fibers. Surfactant (surface active agent) is the secretory product of type II alveolar epithelial cells and covers the alveolar epithelium as a biophysically active thin and continuous film. Here, we briefly review the structural components relevant for gas exchange. Then we describe our current understanding of how these components function under normal conditions and how lung injury results in dysfunction of alveolar micromechanics finally leading to lung fibrosis.
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Affiliation(s)
- Lars Knudsen
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.,REBIRTH Cluster of Excellence, Hannover, Germany
| | - Matthias Ochs
- Institute of Functional and Applied Anatomy, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany. .,Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany. .,REBIRTH Cluster of Excellence, Hannover, Germany.
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18
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Ma R, Wu P, Shi Q, Song D, Fang H. Telocytes promote VEGF expression and alleviate ventilator-induced lung injury in mice. Acta Biochim Biophys Sin (Shanghai) 2018; 50:817-825. [PMID: 29924305 DOI: 10.1093/abbs/gmy066] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Indexed: 01/17/2023] Open
Abstract
Mechanical ventilation (MV) is an important procedure for the treatment of patients with acute lung injury or acute respiratory distress syndrome in a clinical setting; however, MV can lead to severe complications, including ventilator-induced lung injury (VILI). Telocytes (TCs) can promote tissue repair following injury in the heart, kidneys, and other organs. The aim of this study was to investigate the role of TCs in VILI in mice and the associated mechanisms. By using in vivo studies in mice and in vitro studies in cells, we demonstrated that an airway injection of TCs can reduce the pulmonary inflammatory response and improve the lung function in mice with VILI and promote the proliferation of pulmonary vascular endothelial cells. We also demonstrated that the impact of TCs on VILI repair might partially due to vascular endothelial growth factor (VEGF) secreted by TCs upon VILI stimulation, and that VEGF could induce the proliferation of hemangioendothelioma endothelial cells (EOMA). Collectively, our results revealed novel functions of TCs in VILA repair and shed light on the complications that are caused by MV.
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Affiliation(s)
- Ruihua Ma
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Pinwen Wu
- Department of Anesthesiology, Minhang Branch, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Qiqing Shi
- Department of Anesthesiology, Children's Hospital of Fudan University, Shanghai, China
| | - Dongli Song
- Biomedical Research Center, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Hao Fang
- Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai, China
- Department of Anesthesiology, Minhang Branch, Zhongshan Hospital, Fudan University, Shanghai, China
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19
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Blankman P, Shono A, Hermans BJM, Wesselius T, Hasan D, Gommers D. Detection of optimal PEEP for equal distribution of tidal volume by volumetric capnography and electrical impedance tomography during decreasing levels of PEEP in post cardiac-surgery patients. Br J Anaesth 2018; 116:862-9. [PMID: 27199318 PMCID: PMC4872863 DOI: 10.1093/bja/aew116] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/17/2016] [Indexed: 01/26/2023] Open
Abstract
Background Homogeneous ventilation is important for prevention of ventilator-induced lung injury. Electrical impedance tomography (EIT) has been used to identify optimal PEEP by detection of homogenous ventilation in non-dependent and dependent lung regions. We aimed to compare the ability of volumetric capnography and EIT in detecting homogenous ventilation between these lung regions. Methods Fifteen mechanically-ventilated patients after cardiac surgery were studied. Ventilator settings were adjusted to volume-controlled mode with a fixed tidal volume (Vt) of 6–8 ml kg−1 predicted body weight. Different PEEP levels were applied (14 to 0 cm H2O, in steps of 2 cm H2O) and blood gases, Vcap and EIT were measured. Results Tidal impedance variation of the non-dependent region was highest at 6 cm H2O PEEP, and decreased significantly at 14 cm H2O PEEP indicating decrease in the fraction of Vt in this region. At 12 cm H2O PEEP, homogenous ventilation was seen between both lung regions. Bohr and Enghoff dead space calculations decreased from a PEEP of 10 cm H2O. Alveolar dead space divided by alveolar Vt decreased at PEEP levels ≤6 cm H2O. The normalized slope of phase III significantly changed at PEEP levels ≤4 cm H2O. Airway dead space was higher at higher PEEP levels and decreased at the lower PEEP levels. Conclusions In postoperative cardiac patients, calculated dead space agreed well with EIT to detect the optimal PEEP for an equal distribution of inspired volume, amongst non-dependent and dependent lung regions. Airway dead space reduces at decreasing PEEP levels.
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Affiliation(s)
- P Blankman
- Department of Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands
| | - A Shono
- Department of Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands
| | - B J M Hermans
- Institute for Biomedical Technology & Technical Medicine, University of Twente, Enschede, The Netherlands
| | - T Wesselius
- Institute for Biomedical Technology & Technical Medicine, University of Twente, Enschede, The Netherlands
| | - D Hasan
- Department of Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands Institute for Immunotherapy, Duderstadt, Germany
| | - D Gommers
- Department of Adult Intensive Care, Erasmus MC, Room H623, 's Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands
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20
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Chen L, Xia HF, Shang Y, Yao SL. Molecular Mechanisms of Ventilator-Induced Lung Injury. Chin Med J (Engl) 2018; 131:1225-1231. [PMID: 29553050 PMCID: PMC5956775 DOI: 10.4103/0366-6999.226840] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE Mechanical ventilation (MV) has long been used as a life-sustaining approach for several decades. However, researchers realized that MV not only brings benefits to patients but also cause lung injury if used improperly, which is termed as ventilator-induced lung injury (VILI). This review aimed to discuss the pathogenesis of VILI and the underlying molecular mechanisms. DATA SOURCES This review was based on articles in the PubMed database up to December 2017 using the following keywords: "ventilator-induced lung injury", "pathogenesis", "mechanism", and "biotrauma". STUDY SELECTION Original articles and reviews pertaining to mechanisms of VILI were included and reviewed. RESULTS The pathogenesis of VILI was defined gradually, from traditional pathological mechanisms (barotrauma, volutrauma, and atelectrauma) to biotrauma. High airway pressure and transpulmonary pressure or cyclic opening and collapse of alveoli were thought to be the mechanisms of barotraumas, volutrauma, and atelectrauma. In the past two decades, accumulating evidence have addressed the importance of biotrauma during VILI, the molecular mechanism underlying biotrauma included but not limited to proinflammatory cytokines release, reactive oxygen species production, complement activation as well as mechanotransduction. CONCLUSIONS Barotrauma, volutrauma, atelectrauma, and biotrauma contribute to VILI, and the molecular mechanisms are being clarified gradually. More studies are warranted to figure out how to minimize lung injury induced by MV.
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Affiliation(s)
- Lin Chen
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Hai-Fa Xia
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - You Shang
- Department of Critical Care Medicine, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Shang-Long Yao
- Department of Anesthesiology, Institute of Anesthesiology and Critical Care Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
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21
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Nunns GR, Stringham JR, Gamboni F, Moore EE, Fragoso M, Stettler GR, Silliman CC, Banerjee A. Trauma and hemorrhagic shock activate molecular association of 5-lipoxygenase and 5-lipoxygenase-Activating protein in lung tissue. J Surg Res 2018; 229:262-270. [PMID: 29936999 DOI: 10.1016/j.jss.2018.03.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Revised: 02/02/2018] [Accepted: 03/14/2018] [Indexed: 12/20/2022]
Abstract
BACKGROUND Post-traumatic lung injury following trauma and hemorrhagic shock (T/HS) is associated with significant morbidity. Leukotriene-induced inflammation has been implicated in the development of post-traumatic lung injury through a mechanism that is only partially understood. Postshock mesenteric lymph returning to the systemic circulation is rich in arachidonic acid, the substrate of 5-lipoxygenase (ALOX5). ALOX5 is the rate-limiting enzyme in leukotriene synthesis and, following T/HS, contributes to the development of lung dysfunction. ALOX5 colocalizes with its cofactor, 5-lipoxygenase-activating protein (ALOX5AP), which is thought to potentiate ALOX5 synthetic activity. We hypothesized that T/HS results in the molecular association and nuclear colocalization of ALOX5 and ALOX5AP, which ultimately increases leukotriene production and potentiates lung injury. MATERIALS AND METHODS To examine these molecular interactions, a rat T/HS model was used. Post-T/HS tissue was evaluated for lung injury through both histologic analysis of lung sections and biochemical analysis of bronchoalveolar lavage fluid. Lung tissue was immunostained for ALOX5 and ALOX5AP with association and colocalization evaluated by fluorescence resonance energy transfer. In addition, rats undergoing T/HS were treated with MK-886, a known ALOX5AP inhibitor. RESULTS ALOX5 levels increase and ALOX5/ALOX5AP association occurred after T/HS, as evidenced by increases in total tissue fluorescence and fluorescence resonance energy transfer signal intensity, respectively. These findings coincided with increased leukotriene production and with the histological changes characteristic of lung injury. ALOX5/ALOX5AP complex formation, leukotriene production, and lung injury were decreased after inhibition of ALOX5AP with MK-886. CONCLUSIONS These results suggest that the association of ALOX5/ALOX5AP contributes to leukotriene-induced inflammation and predisposes the T/HS animal to lung injury.
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Affiliation(s)
- Geoffrey R Nunns
- School of Medicine, Department of Surgery, Trauma Research Center, University of Colorado Denver, Aurora, Colorado.
| | - John R Stringham
- School of Medicine, Department of Surgery, Trauma Research Center, University of Colorado Denver, Aurora, Colorado
| | - Fabia Gamboni
- School of Medicine, Department of Surgery, Trauma Research Center, University of Colorado Denver, Aurora, Colorado
| | - Ernest E Moore
- School of Medicine, Department of Surgery, Trauma Research Center, University of Colorado Denver, Aurora, Colorado; Denver Health Medical Center, Department of Surgery, Denver, Colorado
| | - Miguel Fragoso
- School of Medicine, Department of Surgery, Trauma Research Center, University of Colorado Denver, Aurora, Colorado; Denver Health Medical Center, Department of Surgery, Denver, Colorado
| | - Gregory R Stettler
- School of Medicine, Department of Surgery, Trauma Research Center, University of Colorado Denver, Aurora, Colorado
| | - Christopher C Silliman
- School of Medicine, Department of Surgery, Trauma Research Center, University of Colorado Denver, Aurora, Colorado; School of Medicine, Department of Pediatrics-Hematology/Oncology, Children's Hospital Colorado, University of Colorado Denver, Aurora, Colorado; Research Laboratory, Bonfils Blood Center, Denver, Colorado
| | - Anirban Banerjee
- School of Medicine, Department of Surgery, Trauma Research Center, University of Colorado Denver, Aurora, Colorado
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22
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Nieman GF, Satalin J, Andrews P, Aiash H, Habashi NM, Gatto LA. Personalizing mechanical ventilation according to physiologic parameters to stabilize alveoli and minimize ventilator induced lung injury (VILI). Intensive Care Med Exp 2017; 5:8. [PMID: 28150228 PMCID: PMC5289131 DOI: 10.1186/s40635-017-0121-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Accepted: 01/26/2017] [Indexed: 12/15/2022] Open
Abstract
It has been shown that mechanical ventilation in patients with, or at high-risk for, the development of acute respiratory distress syndrome (ARDS) can be a double-edged sword. If the mechanical breath is improperly set, it can amplify the lung injury associated with ARDS, causing a secondary ventilator-induced lung injury (VILI). Conversely, the mechanical breath can be adjusted to minimize VILI, which can reduce ARDS mortality. The current standard of care ventilation strategy to minimize VILI attempts to reduce alveolar over-distension and recruitment-derecruitment (R/D) by lowering tidal volume (Vt) to 6 cc/kg combined with adjusting positive-end expiratory pressure (PEEP) based on a sliding scale directed by changes in oxygenation. Thus, Vt is often but not always set as a "one-size-fits-all" approach and although PEEP is often set arbitrarily at 5 cmH2O, it may be personalized according to changes in a physiologic parameter, most often to oxygenation. However, there is evidence that oxygenation as a method to optimize PEEP is not congruent with the PEEP levels necessary to maintain an open and stable lung. Thus, optimal PEEP might not be personalized to the lung pathology of an individual patient using oxygenation as the physiologic feedback system. Multiple methods of personalizing PEEP have been tested and include dead space, lung compliance, lung stress and strain, ventilation patterns using computed tomography (CT) or electrical impedance tomography (EIT), inflection points on the pressure/volume curve (P/V), and the slope of the expiratory flow curve using airway pressure release ventilation (APRV). Although many studies have shown that personalizing PEEP is possible, there is no consensus as to the optimal technique. This review will assess various methods used to personalize PEEP, directed by physiologic parameters, necessary to adaptively adjust ventilator settings with progressive changes in lung pathophysiology.
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Affiliation(s)
- Gary F. Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY USA
| | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY USA
- Cardiopulmonary Critical Care Lab, Department of Surgery, Upstate Medical University, 750 East Adams Street, Syracuse, NY 13210 USA
| | | | - Hani Aiash
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY USA
| | - Nader M. Habashi
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland, Baltimore, MD USA
| | - Louis A. Gatto
- Biological Sciences Department, Biological Sciences Department, SUNY Cortland, Cortland, NY USA
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23
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Kollisch-Singule MC, Jain SV, Andrews PL, Satalin J, Gatto LA, Villar J, De Backer D, Gattinoni L, Nieman GF, Habashi NM. Looking beyond macroventilatory parameters and rethinking ventilator-induced lung injury. J Appl Physiol (1985) 2017; 124:1214-1218. [PMID: 29146685 DOI: 10.1152/japplphysiol.00412.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
| | - Sumeet V Jain
- Department of Surgery, SUNY Upstate Medical University , Syracuse, New York
| | - Penny L Andrews
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine , Baltimore, Maryland
| | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University , Syracuse, New York
| | - Louis A Gatto
- Department of Surgery, SUNY Upstate Medical University , Syracuse, New York.,Department of Biological Sciences, SUNY Cortland, Cortland, New York
| | - Jesús Villar
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III , Madrid , Spain.,Research Unit, Hospital Universitario Dr. Negrin , Las Palmas de Gran Canaria , Spain
| | - Daniel De Backer
- Department of Intensive Care, CHIREC Hospitals, Université Libre de Bruxelles , Brussels , Belgium
| | - Luciano Gattinoni
- Department of Anesthesia and Intensive Care, Georg-August-Universität, Göttingen , Germany
| | - Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University , Syracuse, New York
| | - Nader M Habashi
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine , Baltimore, Maryland
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Nieman GF, Satalin J, Kollisch-Singule M, Andrews P, Aiash H, Habashi NM, Gatto LA. Physiology in Medicine: Understanding dynamic alveolar physiology to minimize ventilator-induced lung injury. J Appl Physiol (1985) 2017; 122:1516-1522. [PMID: 28385915 PMCID: PMC7203565 DOI: 10.1152/japplphysiol.00123.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 03/16/2017] [Accepted: 04/03/2017] [Indexed: 02/01/2023] Open
Abstract
Acute respiratory distress syndrome (ARDS) remains a serious clinical problem with the main treatment being supportive in the form of mechanical ventilation. However, mechanical ventilation can be a double-edged sword: if set improperly, it can exacerbate the tissue damage caused by ARDS; this is known as ventilator-induced lung injury (VILI). To minimize VILI, we must understand the pathophysiologic mechanisms of tissue damage at the alveolar level. In this Physiology in Medicine paper, the dynamic physiology of alveolar inflation and deflation during mechanical ventilation will be reviewed. In addition, the pathophysiologic mechanisms of VILI will be reviewed, and this knowledge will be used to suggest an optimal mechanical breath profile (MBP: all airway pressures, volumes, flows, rates, and the duration that they are applied at both inspiration and expiration) necessary to minimize VILI. Our review suggests that the current protective ventilation strategy, known as the "open lung strategy," would be the optimal lung-protective approach. However, the viscoelastic behavior of dynamic alveolar inflation and deflation has not yet been incorporated into protective mechanical ventilation strategies. Using our knowledge of dynamic alveolar mechanics (i.e., the dynamic change in alveolar and alveolar duct size and shape during tidal ventilation) to modify the MBP so as to minimize VILI will reduce the morbidity and mortality associated with ARDS.
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Affiliation(s)
- Gary F Nieman
- State University of New York Upstate Medical University, Syracuse, New York
| | - Josh Satalin
- State University of New York Upstate Medical University, Syracuse, New York;
| | | | - Penny Andrews
- R Adams Cowley Shock Trauma Center, Baltimore, Maryland
| | - Hani Aiash
- State University of New York Upstate Medical University, Syracuse, New York
- Suez Canal University, Ismailia, Egypt; and
| | | | - Louis A Gatto
- State University of New York Upstate Medical University, Syracuse, New York
- State University of New York Cortland, Cortland, New York
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Ferrando C, Romero C, Tusman G, Suarez-Sipmann F, Canet J, Dosdá R, Valls P, Villena A, Serralta F, Jurado A, Carrizo J, Navarro J, Parrilla C, Romero JE, Pozo N, Soro M, Villar J, Belda FJ. The accuracy of postoperative, non-invasive Air-Test to diagnose atelectasis in healthy patients after surgery: a prospective, diagnostic pilot study. BMJ Open 2017; 7:e015560. [PMID: 28554935 PMCID: PMC5623366 DOI: 10.1136/bmjopen-2016-015560] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
OBJECTIVE To assess the diagnostic accuracy of peripheral capillary oxygen saturation (SpO2) while breathing room air for 5 min (the 'Air-Test') in detecting postoperative atelectasis. DESIGN Prospective cohort study. Diagnostic accuracy was assessed by measuring the agreement between the index test and the reference standard CT scan images. SETTING Postanaesthetic care unit in a tertiary hospital in Spain. PARTICIPANTS Three hundred and fifty patients from 12 January to 7 February 2015; 170 patients scheduled for surgery under general anaesthesia who were admitted into the postsurgical unit were included. INTERVENTION The Air-Test was performed in conscious extubated patients after a 30 min stabilisation period during which they received supplemental oxygen therapy via a venturi mask. The Air-Test was defined as positive when SpO2 was ≤96% and negative when SpO2 was ≥97%. Arterial blood gases were measured in all patients at the end of the Air-Test. In the subsequent 25 min, the presence of atelectasis was evaluated by performing a CT scan in 59 randomly selected patients. MAIN OUTCOME MEASURES The primary study outcome was assessment of the accuracy of the Air-Test for detecting postoperative atelectasis compared with the reference standard. The secondary outcome was the incidence of positive Air-Test results. RESULTS The Air-Test diagnosed postoperative atelectasis with an area under the receiver operating characteristic curve of 0.90 (95% CI 0.82 to 0.98) with a sensitivity of 82.6% and a specificity of 87.8%. The presence of atelectasis was confirmed by CT scans in all patients (30/30) with positive and in 5 patients (17%) with negative Air-Test results. Based on the Air-Test, postoperative atelectasis was present in 36% of the patients (62 out of 170). CONCLUSION The Air-Test may represent an accurate, simple, inexpensive and non-invasive method for diagnosing postoperative atelectasis. TRIAL REGISTRATION NCT02650037.
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Affiliation(s)
- Carlos Ferrando
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
| | - Carolina Romero
- Anesthesiology and Critical Care, Consorci Hospital General Universitari de Valencia, Valencia, Spain
| | - Gerardo Tusman
- Department of Anesthesiology, Hospital Privado de Comunidad, Mar de Plata, Argentina
| | - Fernando Suarez-Sipmann
- Uppsala Universitet, Uppsala, Sweden
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
| | - Jaume Canet
- Anesthesiology and Critical Care, Hospital Universitari Germans Trias i Pujol, Badalona, Spain
| | - Rosa Dosdá
- Department of Radiology, Hospital Clinico Universitario Valencia, Valencia, Spain
| | - Paola Valls
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
| | - Abigail Villena
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
| | - Ferran Serralta
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
| | - Ana Jurado
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
| | - Juan Carrizo
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
| | - Jose Navarro
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
| | - Cristina Parrilla
- Department of Radiology, Hospital Clinico Universitario Valencia, Valencia, Spain
| | - Jose E Romero
- ITACA Institute (Group IBIME), Universidad Politécnica, Valencia, Spain
| | | | - Marina Soro
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
| | - Jesús Villar
- CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
- Research Unit, Hospital Universitario Dr. Negrin, Las Palmas de Gran Canaria, Spain
| | - Francisco Javier Belda
- Anesthesiology and Critical Care, Hospital Clínico Universitario Valencia, Valencia, Spain
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26
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Acosta CM, Tusman G, Costantini M, Echevarría C, Pollioto S, Abrego D, Suarez-Sipmann F, Böhm SH. Doppler images of intra-pulmonary shunt within atelectasis in anesthetized children. Crit Ultrasound J 2016; 8:19. [PMID: 27910005 PMCID: PMC5133206 DOI: 10.1186/s13089-016-0055-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 11/24/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Doppler images of pulmonary vessels in pulmonary diseases associated with subpleural consolidations have been described. Color Doppler easily identifies such vessels within consolidations while spectral Doppler analysis allows the differentiation between pulmonary and bronchial arteries. Thus, Doppler helps in diagnosing the nature of consolidations. To our knowledge, Doppler analysis of pulmonary vessels within anesthesia-induced atelectasis has never been described before. The aim of this case series is to demonstrate the ability of lung ultrasound to detect the shunting of blood within atelectatic lung areas in anesthetized children. FINDINGS Three anesthetized and mechanically ventilated children were scanned in the supine position using a high-resolution linear probe of 6-12 MHz. Once subpleural consolidations were detected in the most dependent posterior lung regions, the probe was rotated such that its long axis followed the intercostal space. In this oblique position, color Doppler mapping was performed to detect blood flow within the consolidation. Thereafter, pulsed waved spectral Doppler was applied in the previously identified vessels during a short expiratory pause, which prevented interferences from respiratory motion. Different flow patterns were identified which corresponded to both, pulmonary and bronchial vessels. Finally, a lung recruitment maneuver was performed which leads to the complete resolution of the aforementioned consolidation thereby confirming the pathophysiological entity of anesthesia-induced atelectasis. CONCLUSIONS Lung ultrasound is a non-invasive imaging tool that not only enables the diagnosis of anesthesia-induced atelectasis in pediatric patients but also analysis of shunting blood within this consolidation.
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Affiliation(s)
- Cecilia M Acosta
- Department of Anesthesia, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar Del Plata, Buenos Aires, Argentina.
| | - Gerardo Tusman
- Department of Anesthesia, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar Del Plata, Buenos Aires, Argentina
| | - Mauro Costantini
- Department of Anesthesia, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar Del Plata, Buenos Aires, Argentina
| | - Camila Echevarría
- Department of Radiology, Hospital Privado de Comunidad, Mar Del Plata, Buenos Aires, Argentina
| | - Sergio Pollioto
- Department of Pediatric Surgery, Hospital Privado de Comunidad, Mar Del Plata, Buenos Aires, Argentina
| | - Diego Abrego
- Department of Pediatric Surgery, Hospital Privado de Comunidad, Mar Del Plata, Buenos Aires, Argentina
| | - Fernando Suarez-Sipmann
- Section of Anesthesia and Critical Care Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University Hospital, Uppsala, Sweden.,CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain
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Tusman G, Acosta CM, Costantini M. Ultrasonography for the assessment of lung recruitment maneuvers. Crit Ultrasound J 2016; 8:8. [PMID: 27496127 PMCID: PMC4975737 DOI: 10.1186/s13089-016-0045-9] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 07/27/2016] [Indexed: 02/07/2023] Open
Abstract
Lung collapse is a known complication that affects most of the patients undergoing positive pressure mechanical ventilation. Such atelectasis and airways closure lead to gas exchange and lung mechanics impairment and has the potential to develop an inflammatory response in the lungs. These negative effects of lung collapse can be reverted by a lung recruitment maneuver (RM) i.e. a ventilatory strategy that resolves lung collapse by a brief and controlled increment in airway pressures. However, an unsolved question is how to assess such RM at the bedside. The aim of this paper is to describe the usefulness of lung sonography (LUS) to conduct and personalize RM in a real-time way at the bedside. LUS has favorable features to assess lung recruitment due to its high specificity and sensitivity to detect lung collapse together with its non-invasiveness, availability and simple use.
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Affiliation(s)
- Gerardo Tusman
- Department of Anesthesiology, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar del Plata, Buenos Aires, Argentina.
| | - Cecilia M Acosta
- Department of Anesthesiology, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar del Plata, Buenos Aires, Argentina
| | - Mauro Costantini
- Department of Anesthesiology, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar del Plata, Buenos Aires, Argentina
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28
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Nieman GF, Gatto LA, Bates JHT, Habashi NM. Mechanical Ventilation as a Therapeutic Tool to Reduce ARDS Incidence. Chest 2016; 148:1396-1404. [PMID: 26135199 DOI: 10.1378/chest.15-0990] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Trauma, hemorrhagic shock, or sepsis can incite systemic inflammatory response syndrome, which can result in early acute lung injury (EALI). As EALI advances, improperly set mechanical ventilation (MV) can amplify early injury into a secondary ventilator-induced lung injury that invariably develops into overt ARDS. Once established, ARDS is refractory to most therapeutic strategies, which have not been able to lower ARDS mortality below the current unacceptably high 40%. Low tidal volume ventilation is one of the few treatments shown to have a moderate positive impact on ARDS survival, presumably by reducing ventilator-induced lung injury. Thus, there is a compelling case to be made that the focus of ARDS management should switch from treatment once this syndrome has become established to the application of preventative measures while patients are still in the EALI stage. Indeed, studies have shown that ARDS incidence is markedly reduced when conventional MV is applied preemptively using a combination of low tidal volume and positive end-expiratory pressure in both patients in the ICU and in surgical patients at high risk for developing ARDS. Furthermore, there is evidence from animal models and high-risk trauma patients that superior prevention of ARDS can be achieved using preemptive airway pressure release ventilation with a very brief duration of pressure release. Preventing rather than treating ARDS may be the way forward in dealing with this recalcitrant condition and would represent a paradigm shift in the way that MV is currently practiced.
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Affiliation(s)
- Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University, Syracuse, NY.
| | | | | | - Nader M Habashi
- R Adams Cowley Shock Trauma Center, University of Maryland Medical Center, Baltimore, MD
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29
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Effects of superimposed tissue weight on regional compliance of injured lungs. Respir Physiol Neurobiol 2016; 228:16-24. [PMID: 26976688 DOI: 10.1016/j.resp.2016.03.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 03/06/2016] [Accepted: 03/06/2016] [Indexed: 11/21/2022]
Abstract
Computed tomography (CT), together with image analysis technologies, enable the construction of regional volume (VREG) and local transpulmonary pressure (PTP,REG) maps of the lung. Purpose of this study is to assess the distribution of VREG vs PTP,REG along the gravitational axis in healthy (HL) and experimental acute lung injury conditions (eALI) at various positive end-expiratory pressures (PEEPs) and inflation volumes. Mechanically ventilated pigs underwent inspiratory hold maneuvers at increasing volumes simultaneously with lung CT scans. eALI was induced via the iv administration of oleic acid. We computed voxel-level VREG vs PTP,REG curves into eleven isogravitational planes by applying polynomial regressions. Via F-test, we determined that VREG vs PTP,REG curves derived from different anatomical planes (p-values<1.4E-3), exposed to different PEEPs (p-values<1.5E-5) or subtending different lung status (p-values<3E-3) were statistically different (except for two cases of adjacent planes). Lung parenchyma exhibits different elastic behaviors based on its position and the density of superimposed tissue which can increase during lung injury.
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30
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Tusman G, Acosta CM, Nicola M, Esperatti M, Bohm SH, Suarez-Sipmann F. Real-time images of tidal recruitment using lung ultrasound. Crit Ultrasound J 2015; 7:19. [PMID: 26660526 PMCID: PMC4676770 DOI: 10.1186/s13089-015-0036-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/24/2015] [Indexed: 12/14/2022] Open
Abstract
Background Ventilator-induced lung injury is a form of mechanical damage leading to a pulmonary inflammatory response related to the use of mechanical ventilation enhanced by the presence of atelectasis. One proposed mechanism of this injury is the repetitive opening and closing of collapsed alveoli and small airways within these atelectatic areas—a phenomenon called tidal recruitment. The presence of tidal recruitment is difficult to detect, even with high-resolution images of the lungs like CT scan. The purpose of this article is to give evidence of tidal recruitment by lung ultrasound. Findings A standard lung ultrasound inspection detected lung zones of atelectasis in mechanically ventilated patients. With a linear probe placed in the intercostal oblique position. We observed tidal recruitment within atelectasis as an improvement in aeration at the end of inspiration followed by the re-collapse at the end of expiration. This mechanism disappeared after the performance of a lung recruitment maneuver. Conclusions Lung ultrasound was helpful in detecting the presence of atelectasis and tidal recruitment and in confirming their resolution after a lung recruitment maneuver. Electronic supplementary material The online version of this article (doi:10.1186/s13089-015-0036-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gerardo Tusman
- Department of Anesthesia, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar del Plata, Buenos Aires, Argentina.
| | - Cecilia M Acosta
- Department of Anesthesia, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar del Plata, Buenos Aires, Argentina.
| | - Marco Nicola
- Department of Anesthesia, Hospital Privado de Comunidad, Córdoba 4545, 7600, Mar del Plata, Buenos Aires, Argentina.
| | - Mariano Esperatti
- Intensive Care Medicine, Hospital Privado de Comunidad, Mar del Plata, Buenos Aires, Argentina.
| | | | - Fernando Suarez-Sipmann
- Department of Surgical Sciences, Section of Anesthesia and Critical Care Hedenstierna Laboratory, Uppsala University Hospital, Uppsala, Sweden. .,CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, Spain.
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31
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Cereda M, Xin Y, Hamedani H, Clapp J, Kadlecek S, Meeder N, Zeng J, Profka H, Kavanagh BP, Rizi RR. Mild loss of lung aeration augments stretch in healthy lung regions. J Appl Physiol (1985) 2015; 120:444-54. [PMID: 26662053 DOI: 10.1152/japplphysiol.00734.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 12/07/2015] [Indexed: 11/22/2022] Open
Abstract
Inspiratory stretch by mechanical ventilation worsens lung injury. However, it is not clear whether and how the ventilator damages lungs in the absence of preexisting injury. We hypothesized that subtle loss of lung aeration during general anesthesia regionally augments ventilation and distension of ventilated air spaces. In eight supine anesthetized and intubated rats, hyperpolarized gas MRI was performed after a recruitment maneuver following 1 h of volume-controlled ventilation with zero positive end-expiratory pressure (ZEEP), FiO2 0.5, and tidal volume 10 ml/kg, and after a second recruitment maneuver. Regional fractional ventilation (FV), apparent diffusion coefficient (ADC) of (3)He (a measurement of ventilated peripheral air space dimensions), and gas volume were measured in lung quadrants of ventral and dorsal regions of the lungs. In six additional rats, computed tomography (CT) images were obtained at each time point. Ventilation with ZEEP decreased total lung gas volume and increased both FV and ADC in all studied regions. Increases in FV were more evident in the dorsal slices. In each lung quadrant, higher ADC was predicted by lower gas volume and by increased mean values (and heterogeneity) of FV distribution. CT scans documented 10% loss of whole-lung aeration and increased density in the dorsal lung, but no macroscopic atelectasis. Loss of pulmonary gas at ZEEP increased fractional ventilation and inspiratory dimensions of ventilated peripheral air spaces. Such regional changes could help explain a propensity for mechanical ventilation to contribute to lung injury in previously uninjured lungs.
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Affiliation(s)
- Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania;
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Justin Clapp
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Natalie Meeder
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Johnathan Zeng
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Harrilla Profka
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Brian P Kavanagh
- Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
| | - Rahim R Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania; and
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32
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Tingay DG, Lavizzari A, Zonneveld CEE, Rajapaksa A, Zannin E, Perkins E, Black D, Sourial M, Dellacà RL, Mosca F, Adler A, Grychtol B, Frerichs I, Davis PG. An individualized approach to sustained inflation duration at birth improves outcomes in newborn preterm lambs. Am J Physiol Lung Cell Mol Physiol 2015; 309:L1138-49. [DOI: 10.1152/ajplung.00277.2015] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 09/17/2015] [Indexed: 01/18/2023] Open
Abstract
A sustained first inflation (SI) at birth may aid lung liquid clearance and aeration, but the impact of SI duration relative to the volume-response of the lung is poorly understood. We compared three SI strategies: 1) variable duration defined by attaining volume equilibrium using real-time electrical impedance tomography (EIT; SIplat); 2) 30 s beyond equilibrium (SIlong); 3) short 30-s SI (SI30); and 4) positive pressure ventilation without SI (no-SI) on spatiotemporal aeration and ventilation (EIT), gas exchange, lung mechanics, and regional early markers of injury in preterm lambs. Fifty-nine fetal-instrumented lambs were ventilated for 60 min after applying the allocated first inflation strategy. At study completion molecular and histological markers of lung injury were analyzed. The time to SI volume equilibrium, and resultant volume, were highly variable; mean (SD) 55 (34) s, coefficient of variability 59%. SIplat and SIlong resulted in better lung mechanics, gas exchange and lower ventilator settings than both no-SI and SI30. At 60 min, alveolar-arterial difference in oxygen was a mean (95% confidence interval) 130 (13, 249) higher in SI30 vs. SIlong group (two-way ANOVA). These differences were due to better spatiotemporal aeration and tidal ventilation, although all groups showed redistribution of aeration towards the nondependent lung by 60 min. Histological lung injury scores mirrored spatiotemporal change in aeration and were greatest in SI30 group ( P < 0.01, Kruskal-Wallis test). An individualized volume-response approach to SI was effective in optimizing aeration, homogeneous tidal ventilation, and respiratory outcomes, while an inadequate SI duration had no benefit over positive pressure ventilation alone.
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Affiliation(s)
- David G. Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
- Neonatology, The Royal Children's Hospital, Parkville, Australia
- Neonatal Research, The Royal Women's Hospital, Parkville, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Anna Lavizzari
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
- Neonatal Intensive Care Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda, Ospedale Maggiore Policlinico-Università Degli Studi di Milano, Milano, Italy
| | | | - Anushi Rajapaksa
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
| | - Emanuela Zannin
- Laboratorio di Tecnologie Biomediche, Dipartimento di Elettronica, Informazione e Ingegneria Biomedica-DEIB, Politecnico di Milano University, Milano, Italy
| | - Elizabeth Perkins
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
| | - Don Black
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
| | - Magdy Sourial
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
| | - Raffaele L. Dellacà
- Laboratorio di Tecnologie Biomediche, Dipartimento di Elettronica, Informazione e Ingegneria Biomedica-DEIB, Politecnico di Milano University, Milano, Italy
| | - Fabio Mosca
- Neonatal Intensive Care Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico Ca' Granda, Ospedale Maggiore Policlinico-Università Degli Studi di Milano, Milano, Italy
| | - Andy Adler
- Systems and Computer Engineering, Carleton University, Ottawa, Canada
| | - Bartłomiej Grychtol
- Fraunhofer Project Group for Automation in Medicine and Biotechnology, Mannheim, Germany
| | - Inéz Frerichs
- Department of Anaesthesiology and Intensive Care Medicine, University Medical Centre Schleswig-Holstein, Campus Kiel, Kiel, Germany; and
| | - Peter G. Davis
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
- Neonatal Research, The Royal Women's Hospital, Parkville, Australia
- Department of Obstetrics and Gynaecology, University of Melbourne, Melbourne, Australia
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33
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Nieman GF, Gatto LA, Habashi NM. Impact of mechanical ventilation on the pathophysiology of progressive acute lung injury. J Appl Physiol (1985) 2015; 119:1245-61. [PMID: 26472873 DOI: 10.1152/japplphysiol.00659.2015] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 10/01/2015] [Indexed: 02/08/2023] Open
Abstract
The earliest description of what is now known as the acute respiratory distress syndrome (ARDS) was a highly lethal double pneumonia. Ashbaugh and colleagues (Ashbaugh DG, Bigelow DB, Petty TL, Levine BE Lancet 2: 319-323, 1967) correctly identified the disease as ARDS in 1967. Their initial study showing the positive effect of mechanical ventilation with positive end-expiratory pressure (PEEP) on ARDS mortality was dampened when it was discovered that improperly used mechanical ventilation can cause a secondary ventilator-induced lung injury (VILI), thereby greatly exacerbating ARDS mortality. This Synthesis Report will review the pathophysiology of ARDS and VILI from a mechanical stress-strain perspective. Although inflammation is also an important component of VILI pathology, it is secondary to the mechanical damage caused by excessive strain. The mechanical breath will be deconstructed to show that multiple parameters that comprise the breath-airway pressure, flows, volumes, and the duration during which they are applied to each breath-are critical to lung injury and protection. Specifically, the mechanisms by which a properly set mechanical breath can reduce the development of excessive fluid flux and pulmonary edema, which are a hallmark of ARDS pathology, are reviewed. Using our knowledge of how multiple parameters in the mechanical breath affect lung physiology, the optimal combination of pressures, volumes, flows, and durations that should offer maximum lung protection are postulated.
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Affiliation(s)
- Gary F Nieman
- Department of Surgery, Upstate Medical University, Syracuse, New York;
| | - Louis A Gatto
- Biological Sciences Department, State University of New York, Cortland, New York; and
| | - Nader M Habashi
- R Adams Cowley Shock/Trauma Center, University of Maryland Medical Center, Baltimore, Maryland
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34
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Carrasco Loza R, Villamizar Rodríguez G, Medel Fernández N. Ventilator-Induced Lung Injury (VILI) in Acute Respiratory Distress Syndrome (ARDS): Volutrauma and Molecular Effects. Open Respir Med J 2015; 9:112-9. [PMID: 26312103 PMCID: PMC4541417 DOI: 10.2174/1874306401509010112] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2015] [Revised: 04/16/2015] [Accepted: 04/16/2015] [Indexed: 01/03/2023] Open
Abstract
Acute Respiratory Distress Syndrome (ARDS) is a clinical condition secondary to a variety of insults leading to a severe acute respiratory failure and high mortality in critically ill patients. Patients with ARDS generally require mechanical ventilation, which is another important factor that may increase the ALI (acute lung injury) by a series of pathophysiological mechanisms, whose common element is the initial volutrauma in the alveolar units, and forming part of an entity known clinically as ventilator-induced lung injury (VILI). Injured lungs can be partially protected by optimal settings and ventilation modes, using low tidal volume (VT) values and high positive-end expiratory pressure (PEEP). The benefits in ARDS outcomes caused by these interventions have been confirmed by several prospective randomized controlled trials (RCTs) and are attributed to reduction in volutrauma. The purpose of this article is to present an approach to VILI pathophysiology focused on the effects of volutrauma that lead to lung injury and the ‘mechanotransduction’ mechanism. A more complete understanding about the molecular effects that physical forces could have, is essential for a better assessment of existing strategies as well as the development of new therapeutic strategies to reduce the damage resulting from VILI, and thereby contribute to reducing mortality in ARDS.
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Affiliation(s)
- R Carrasco Loza
- Laboratorio de Investigación Biomédica, Hospital del Salvador, Facultad de Medicina, Universidad de Chile, Santiago, Chile ; Unidad de Cuidados Intensivos, Clínica Dávila, Santiago, Chile
| | | | - N Medel Fernández
- Laboratorio de Investigación Biomédica, Hospital del Salvador, Facultad de Medicina, Universidad de Chile, Santiago, Chile ; Unidad de Cuidados Intensivos, Clínica Dávila, Santiago, Chile
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35
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Andrews PL, Sadowitz B, Kollisch-Singule M, Satalin J, Roy S, Snyder K, Gatto LA, Nieman GF, Habashi NM. Alveolar instability (atelectrauma) is not identified by arterial oxygenation predisposing the development of an occult ventilator-induced lung injury. Intensive Care Med Exp 2015. [PMID: 26215818 PMCID: PMC4480795 DOI: 10.1186/s40635-015-0054-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Improperly set mechanical ventilation (MV) with normal lungs can advance lung injury and increase the incidence of acute respiratory distress syndrome (ARDS). A key mechanism of ventilator-induced lung injury (VILI) is an alteration in alveolar mechanics including alveolar instability or recruitment/derecruitment (R/D). We hypothesize that R/D cannot be identified by PaO2 (masking occult VILI), and if protective ventilation is not applied, ARDS incidence will increase. METHODS Sprague-Dawley rats (n = 8) were anesthetized, surgically instrumented, and placed on MV. A thoracotomy was performed and an in vivo microscope attached to the pleural surface of the lung with baseline dynamic changes in alveolar size during MV recorded. Alveolar instability was induced by intra-tracheal instillation of Tween and alveolar R/D identified as a marked change in alveolar size from inspiration to expiration with increases in positive end-expiratory pressure (PEEP) levels. RESULTS Despite maintaining a clinically acceptable PaO2 (55-80 mmHg), the alveoli remained unstable with significant R/D at low PEEP levels. Although PaO2 consistently increased with an increase in PEEP, R/D did not plateau until PEEP was >9 cmH2O. CONCLUSIONS PaO2 remained clinically acceptable while alveolar instability persisted at all levels of PEEP (especially PEEP <9 cmH2O). Therefore, PaO2 levels cannot be used reliably to guide protective MV strategies or infer that VILI is not occurring. Using PaO2 to set a PEEP level necessary to stabilize the alveoli could underestimate the potential for VILI. These findings highlight the need for more accurate marker(s) of alveolar stability to guide protective MV necessary to prevent VILI.
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Affiliation(s)
- Penny L Andrews
- Department of Critical Care, R Adams Cowley Shock Trauma Center, Baltimore, MD, USA,
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36
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Ferrando C, Soro M, Canet J, Unzueta MC, Suárez F, Librero J, Peiró S, Llombart A, Delgado C, León I, Rovira L, Ramasco F, Granell M, Aldecoa C, Diaz O, Balust J, Garutti I, de la Matta M, Pensado A, Gonzalez R, Durán ME, Gallego L, Del Valle SG, Redondo FJ, Diaz P, Pestaña D, Rodríguez A, Aguirre J, García JM, García J, Espinosa E, Charco P, Navarro J, Rodríguez C, Tusman G, Belda FJ. Rationale and study design for an individualized perioperative open lung ventilatory strategy (iPROVE): study protocol for a randomized controlled trial. Trials 2015; 16:193. [PMID: 25927183 PMCID: PMC4425893 DOI: 10.1186/s13063-015-0694-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Accepted: 03/30/2015] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Postoperative pulmonary and non-pulmonary complications are common problems that increase morbidity and mortality in surgical patients, even though the incidence has decreased with the increased use of protective lung ventilation strategies. Previous trials have focused on standard strategies in the intraoperative or postoperative period, but without personalizing these strategies to suit the needs of each individual patient and without considering both these periods as a global perioperative lung-protective approach. The trial presented here aims at comparing postoperative complications when using an individualized ventilatory management strategy in the intraoperative and immediate postoperative periods with those when using a standard protective ventilation strategy in patients scheduled for major abdominal surgery. METHODS This is a comparative, prospective, multicenter, randomized, and controlled, four-arm trial that will include 1012 patients with an intermediate or high risk for postoperative pulmonary complications. The patients will be divided into four groups: (1) individualized perioperative group: intra- and postoperative individualized strategy; (2) intraoperative individualized strategy + postoperative continuous positive airway pressure (CPAP); (3) intraoperative standard ventilation + postoperative CPAP; (4) intra- and postoperative standard strategy (conventional strategy). The primary outcome is a composite analysis of postoperative complications. DISCUSSION The Individualized Perioperative Open-lung Ventilatory Strategy (iPROVE) is the first multicenter, randomized, and controlled trial to investigate whether an individualized perioperative approach prevents postoperative pulmonary complications. TRIAL REGISTRATION Registered on 5 June 2014 with identification no. NCT02158923 .
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Affiliation(s)
- Carlos Ferrando
- Anesthesiology and Critical Care Department, Hospital Clínico of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain.
| | - Marina Soro
- Anesthesiology and Critical Care Department, Hospital Clínico of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain.
| | - Jaume Canet
- Anesthesiology and Critical Care Department, Hospital Germans Tries i Pujol, Carretera de Canyet s/n, 08916, Badalona, Spain.
| | - Ma Carmen Unzueta
- Anesthesiology and Critical Care Department, Hospital San Pau, Carrer de Sant Quintí, 89, CP: 08026, Barcelona, Spain.
| | - Fernando Suárez
- Intensive Care Department, Uppsala University Hospital, Suecia Akademiska Sjukhuset Uppsala University, CP: 75185, Uppsala, Sweden.
| | - Julián Librero
- FISABIO salud Pública, Av. Cataluña, 21, CP: 46020, Valencia, Spain.
| | - Salvador Peiró
- FISABIO salud Pública, Av. Cataluña, 21, CP: 46020, Valencia, Spain.
| | - Alicia Llombart
- Anesthesiology and Critical Care Department, Hospital Clínico of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain.
| | - Carlos Delgado
- Anesthesiology and Critical Care Department, Hospital Clínico of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain.
| | - Irene León
- Anesthesiology and Critical Care Department, Hospital Clínico of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain.
| | - Lucas Rovira
- Anesthesiology and Critical Care Department, Hospital de Manises, Av. De la Generalitat Valenciana, Manises, CP: 46940, Spain.
| | - Fernando Ramasco
- Anesthesiology and Critical Care Department, Hospital La Princesa of Madrid, Calle de Diego León, 62, CP: 28006, Madrid, Spain.
| | - Manuel Granell
- Anesthesiology and Critical Care Department, Hospital General of Valencia, Av. De les Tres Creus, 2, Valencia, CP: 46014, Spain.
| | - César Aldecoa
- Anesthesiology and Critical Care Department, Hospital Río Hortega of Valladolid, Calle Dulzaina, 2, Valladolid, CP 47012, Spain.
| | - Oscar Diaz
- Anesthesiology and Critical Care Department, Hospital La Fe of Valencia, Av. De Fernando Abril Martorell, 106, Valencia, CP: 46026, Spain.
| | - Jaume Balust
- Anesthesiology and Critical Care Department, Hospital Clínic i Provincial of Barcelona, Carrer Villarroel 170, Barcelona, CP: 08036, Spain.
| | - Ignacio Garutti
- Anesthesiology and Critical Care Department, Hospital General Gregorio Marañon of Madrid, Calle del Doctor Esquerdo, 46, Madrid, CP: 28007, Spain.
| | - Manuel de la Matta
- Anesthesiology and Critical Care Department, Hospital Vírgen del Rocio of Sevilla, Av. Manuel Siurot s/n, Sevilla, CP: 41013, Spain.
| | - Alberto Pensado
- Anesthesiology and Critical Care Department, Complejo Hospitalario Juan Canalejo of La Coruña, Xubias, 84, La Coruña, CP: 15006, Spain.
| | - Rafael Gonzalez
- Anesthesiology and Critical Care Department, Hospital of León, C/ Altos de Nava s/n, Leon, CP: 24701, Spain.
| | - M Eugenia Durán
- Anesthesiology and Critical Care Department, Hospital Vírgen de la Arraixaca of Murcia, Carretera de Madrid-Cartagena s/n, Madrird, CP: 30120, Spain.
| | - Lucia Gallego
- Anesthesiology and Critical Care Department, Hospital Miguel Servet of Zaragoza, Paseo Isabel la Católica, 1-3, Zaragoza, CP: 50009, Spain.
| | - Santiago García Del Valle
- Anesthesiology and Critical Care Department, Hospital Fundación of Alcorcón, Calle de Valdelaguna, 1, Alcorcón, CP: 28922, Spain.
| | - Francisco J Redondo
- Anesthesiology and Critical Care Department, Hospital General of Ciudad Real, C/ Alisos, 19, Ciudad Real, CP: 13002, Spain.
| | - Pedro Diaz
- Anesthesiology and Critical Care Department, Hospital de Valme of Sevilla, Av. Bellavista s/n, Sevilla, CP: 41014, Spain.
| | - David Pestaña
- Anesthesiology and Critical Care Department, Hospital Ramón y Cajal of Madrid, Carretera de Colmenar Viejo Km 9, Madrid, CP: 28034, Spain.
| | - Aurelio Rodríguez
- Anesthesiology and Critical Care Department, Hospital de Gran Canaria Dr. Negrín, c/ Barranco de la Ballena s/n, Negrin, CP: 35010, Spain.
| | - Javier Aguirre
- Anesthesiology and Critical Care Department, Hospital of Galdakano, Barrio Labeaga s/n, Galdakano, CP: 48960, Spain.
| | - Jose M García
- Anesthesiology and Critical Care Department, Complejo Hospitalario Juan Ramón Jimenez of Huelva, Ronda exterior norte, s/n, Huelva, CP: 21005, Spain.
| | - Javier García
- Anesthesiology and Critical Care Department, Hospital Puerta de Hierro of Majadahonda, C/ Manuel de Falla, 1, Majadahonda, CP: 28222, Spain.
| | - Elena Espinosa
- Anesthesiology and Critical Care Department, Hospital Nuestra Señora de la Candelaria of Santa Cruz de Tenerife, Carretera del Rosario, 145, Santa Cruz de Tenerife, CP: 38010, Spain.
| | - Pedro Charco
- Anesthesiology and Critical Care Department, Hospital Son Espases of Mallorca, Carretera de la Valldemosa, 79, Mallorca, CP: 07120, Spain.
| | - Jose Navarro
- Anesthesiology and Critical Care Department, Hospital General of Alicante, Pintor Baeza, 12, Alicante, CP: 03010, Spain.
| | - Clara Rodríguez
- FISABIO salud Pública, Av. Cataluña, 21, CP: 46020, Valencia, Spain.
| | - Gerardo Tusman
- Anesthesiology Department, Hospital Privado de Comunidad Mar de Plata, Mar de Plata, Argentina.
| | - Francisco Javier Belda
- Anesthesiology and Critical Care Department, Hospital Clínico of Valencia, Av. Blasco Ibañez, 17, Valencia, CP: 46010, Spain.
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Cereda M, Xin Y, Kadlecek S, Hamedani H, Rajaei J, Clapp J, Rizi RR. Hyperpolarized gas diffusion MRI for the study of atelectasis and acute respiratory distress syndrome. NMR IN BIOMEDICINE 2014; 27:1468-78. [PMID: 24920074 PMCID: PMC4232982 DOI: 10.1002/nbm.3136] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 04/03/2014] [Accepted: 04/21/2014] [Indexed: 06/03/2023]
Abstract
Considerable uncertainty remains about the best ventilator strategies for the mitigation of atelectasis and associated airspace stretch in patients with acute respiratory distress syndrome (ARDS). In addition to several immediate physiological effects, atelectasis increases the risk of ventilator-associated lung injury, which has been shown to significantly worsen ARDS outcomes. A number of lung imaging techniques have made substantial headway in clarifying the mechanisms of atelectasis. This paper reviews the contributions of computed tomography, positron emission tomography, and conventional MRI to understanding this phenomenon. In doing so, it also reveals several important shortcomings inherent to each of these approaches. Once these shortcomings have been made apparent, we describe how hyperpolarized (HP) gas MRI--a technique that is uniquely able to assess responses to mechanical ventilation and lung injury in peripheral airspaces--is poised to fill several of these knowledge gaps. The HP-MRI-derived apparent diffusion coefficient (ADC) quantifies the restriction of (3) He diffusion by peripheral airspaces, thereby obtaining pulmonary structural information at an extremely small scale. Lastly, this paper reports the results of a series of experiments that measured ADC in mechanically ventilated rats in order to investigate (i) the effect of atelectasis on ventilated airspaces, (ii) the relationship between positive end-expiratory pressure (PEEP), hysteresis, and the dimensions of peripheral airspaces, and (iii) the ability of PEEP and surfactant to reduce airspace dimensions after lung injury. An increase in ADC was found to be a marker of atelectasis-induced overdistension. With recruitment, higher airway pressures were shown to reduce stretch rather than worsen it. Moving forward, HP MRI has significant potential to shed further light on the atelectatic processes that occur during mechanical ventilation.
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Affiliation(s)
- Maurizio Cereda
- Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi Xin
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Stephen Kadlecek
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Hooman Hamedani
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Jennia Rajaei
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Justin Clapp
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
| | - Rahim R. Rizi
- Department of Radiology, University of Pennsylvania, Philadelphia, PA, USA
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Perchiazzi G, Rylander C, Derosa S, Pellegrini M, Pitagora L, Polieri D, Vena A, Tannoia A, Fiore T, Hedenstierna G. Regional distribution of lung compliance by image analysis of computed tomograms. Respir Physiol Neurobiol 2014; 201:60-70. [PMID: 25026158 DOI: 10.1016/j.resp.2014.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/01/2014] [Accepted: 07/02/2014] [Indexed: 10/25/2022]
Abstract
Computed tomography (CT) can yield quantitative information about volume distribution in the lung. By combining information provided by CT and respiratory mechanics, this study aims at quantifying regional lung compliance (CL) and its distribution and homogeneity in mechanically ventilated pigs. The animals underwent inspiratory hold maneuvers at 12 lung volumes with simultaneous CT exposure at two end-expiratory pressure levels and before and after acute lung injury (ALI) by oleic acid administration. CL and the sum of positive voxel compliances from CT were linearly correlated; negative compliance areas were found. A remarkably heterogeneous distribution of voxel compliance was found in the injured lungs. As the lung inflation increased, the homogeneity increased in healthy lungs but decreased in injured lungs. Image analysis brought novel findings regarding spatial homogeneity of compliance, which increases in ALI but not in healthy lungs by applying PEEP after a recruitment maneuver.
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Affiliation(s)
- Gaetano Perchiazzi
- Emergency and Organ Transplant, Bari University, Bari, Italy; Medical Sciences - Clinical Physiology, Uppsala University, Uppsala, Sweden.
| | - Christian Rylander
- Anaesthesia and Intensive Care Medicine, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Savino Derosa
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | | | | | - Debora Polieri
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Antonio Vena
- Intensive Care Unit, SS Annunziata Hospital, Taranto, Italy
| | - Angela Tannoia
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Tommaso Fiore
- Emergency and Organ Transplant, Bari University, Bari, Italy
| | - Göran Hedenstierna
- Medical Sciences - Clinical Physiology, Uppsala University, Uppsala, Sweden
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Protective Ventilatory Approaches to One-Lung Ventilation: More than Reduction of Tidal Volume. CURRENT ANESTHESIOLOGY REPORTS 2014. [DOI: 10.1007/s40140-014-0057-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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40
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Abstract
Interleukins are critical immune modulators and since their first description in 1977, there has been a steady increase in the recognition of their roles in many paediatric respiratory diseases. This basic and clinical knowledge is now maturing into both approved and investigational therapies aimed at blocking or modifying the interleukin response. The purpose of this review is to bring up to date what is known about interleukin function in paediatric pulmonology, focusing on nine important lung conditions. This is followed by summaries about 18 interleukins which have been associated with these paediatric pulmonary conditions. Throughout, emphasis is placed on where interventions have been tested. Over the next several years, it is likely that many more treatments based on interleukin biology and function will become available and understanding the basis for these therapies will allow the practicing paediatric pulmonologist to take appropriate advantage of them.
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Affiliation(s)
- Henry J Rozycki
- Division of Neonatal Medicine, Department of Pediatrics, Children's Hospital of Richmond at VCU and Virginia Commonwealth University, Richmond, VA USA.
| | - Wei Zhao
- Division of Allergy and Immunology, Department of Pediatrics, Children's Hospital of Richmond at VCU and Virginia Commonwealth University, Richmond, VA USA.
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41
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Tingay DG, Wallace MJ, Bhatia R, Schmölzer GM, Zahra VA, Dolan MJ, Hooper SB, Davis PG. Surfactant before the first inflation at birth improves spatial distribution of ventilation and reduces lung injury in preterm lambs. J Appl Physiol (1985) 2013; 116:251-8. [PMID: 24356523 DOI: 10.1152/japplphysiol.01142.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The interrelationship between the role of surfactant and a sustained inflation (SI) to aid ex utero transition of the preterm lung is unknown. We compared the effect of surfactant administered before and after an initial SI on gas exchange, lung mechanics, spatial distribution of ventilation, and lung injury in preterm lambs. Gestational-age lambs (127 days; 9 per group) received 100 mg/kg of a surfactant (Curosurf) either prior (Surf+SI) or 10 min after birth (SI+Surf). At birth, a 20-s, 35 cmH2O SI was applied, followed by 70 min of positive pressure ventilation. Oxygenation, carbon dioxide removal, respiratory system compliance, end-expiratory thoracic volume (via respiratory inductive plethysmography), and distribution of end-expiratory volume and ventilation (via electrical impedance tomography) were measured throughout. Early markers of lung injury were analyzed using quantitative RT-PCR. During the first 15 min, oxygenation, carbon dioxide removal, and compliance were better in the Surf+SI group (all P < 0.05). End-expiratory volume on completion of the sustained inflation was higher in the Surf+SI group than the SI+Surf group; 11 ± 1 ml/kg vs. 7 ± 1 ml/kg (mean ± SE) (P = 0.043; t-test), but was not different at later time points. Although neither achieved homogenous aeration, spatial ventilation was more uniform in the Surf+SI group throughout; 50.1 ± 10.9% of total ventilation in the left hemithorax at 70 min vs. 42.6 ± 11.1% in the SI+Surf group. Surf+SI resulted in lower mRNA levels of CYR61 and EGR1 compared with SI+Surf (P < 0.001, one-way ANOVA). Surfactant status of the fetal preterm lung at birth influences the mechanical and injury response to a sustained inflation and ventilation by changing surface tension of the air/fluid interface.
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Affiliation(s)
- David G Tingay
- Neonatal Research, Murdoch Childrens Research Institute, Parkville, Australia
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42
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Abstract
Mechanical ventilation (MV) is, by definition, the application of external forces to the lungs. Depending on their magnitude, these forces can cause a continuum of pathophysiological alterations ranging from the stimulation of inflammation to the disruption of cell-cell contacts and cell membranes. These side effects of MV are particularly relevant for patients with inhomogeneously injured lungs such as in acute lung injury (ALI). These patients require supraphysiological ventilation pressures to guarantee even the most modest gas exchange. In this situation, ventilation causes additional strain by overdistension of the yet non-injured region, and additional stress that forms because of the interdependence between intact and atelectatic areas. Cells are equipped with elaborate mechanotransduction machineries that respond to strain and stress by the activation of inflammation and repair mechanisms. Inflammation is the fundamental response of the host to external assaults, be they of mechanical or of microbial origin and can, if excessive, injure the parenchymal tissue leading to ALI. Here, we will discuss the forces generated by MV and how they may injure the lungs mechanically and through inflammation. We will give an overview of the mechanotransduction and how it leads to inflammation and review studies demonstrating that ventilator-induced lung injury can be prevented by blocking pathways of mechanotransduction or inflammation.
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Affiliation(s)
- Ulrike Uhlig
- Department of Pharmacology & Toxicology, Medical Faculty, RWTH Aachen University, Aachen, Germany
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43
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Parker JC. Acute lung injury and pulmonary vascular permeability: use of transgenic models. Compr Physiol 2013; 1:835-82. [PMID: 23737205 DOI: 10.1002/cphy.c100013] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Acute lung injury is a general term that describes injurious conditions that can range from mild interstitial edema to massive inflammatory tissue destruction. This review will cover theoretical considerations and quantitative and semi-quantitative methods for assessing edema formation and increased vascular permeability during lung injury. Pulmonary edema can be quantitated directly using gravimetric methods, or indirectly by descriptive microscopy, quantitative morphometric microscopy, altered lung mechanics, high-resolution computed tomography, magnetic resonance imaging, positron emission tomography, or x-ray films. Lung vascular permeability to fluid can be evaluated by measuring the filtration coefficient (Kf) and permeability to solutes evaluated from their blood to lung clearances. Albumin clearances can then be used to calculate specific permeability-surface area products (PS) and reflection coefficients (σ). These methods as applied to a wide variety of transgenic mice subjected to acute lung injury by hyperoxic exposure, sepsis, ischemia-reperfusion, acid aspiration, oleic acid infusion, repeated lung lavage, and bleomycin are reviewed. These commonly used animal models simulate features of the acute respiratory distress syndrome, and the preparation of genetically modified mice and their use for defining specific pathways in these disease models are outlined. Although the initiating events differ widely, many of the subsequent inflammatory processes causing lung injury and increased vascular permeability are surprisingly similar for many etiologies.
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Affiliation(s)
- James C Parker
- Department of Physiology, University of South Alabama, Mobile, Alabama, USA.
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Namati E, Warger WC, Unglert CI, Eckert JE, Hostens J, Bouma BE, Tearney GJ. Four-dimensional visualization of subpleural alveolar dynamics in vivo during uninterrupted mechanical ventilation of living swine. BIOMEDICAL OPTICS EXPRESS 2013; 4:2492-506. [PMID: 24298409 PMCID: PMC3829543 DOI: 10.1364/boe.4.002492] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/24/2013] [Accepted: 08/28/2013] [Indexed: 05/04/2023]
Abstract
Pulmonary alveoli have been studied for many years, yet no unifying hypothesis exists for their dynamic mechanics during respiration due to their miniature size (100-300 μm dimater in humans) and constant motion, which prevent standard imaging techniques from visualizing four-dimensional dynamics of individual alveoli in vivo. Here we report a new platform to image the first layer of air-filled subpleural alveoli through the use of a lightweight optical frequency domain imaging (OFDI) probe that can be placed upon the pleura to move with the lung over the complete range of respiratory motion. This device enables in-vivo acquisition of four-dimensional microscopic images of alveolar airspaces (alveoli and ducts), within the same field of view, during continuous ventilation without restricting the motion or modifying the structure of the alveoli. Results from an exploratory study including three live swine suggest that subpleural alveolar air spaces are best fit with a uniform expansion (r (2) = 0.98) over a recruitment model (r (2) = 0.72). Simultaneously, however, the percentage change in volume shows heterogeneous alveolar expansion within just a 1 mm x 1 mm field of view. These results signify the importance of four-dimensional imaging tools, such as the device presented here. Quantification of the dynamic response of the lung during ventilation may help create more accurate modeling techniques and move toward a more complete understanding of alveolar mechanics.
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Affiliation(s)
- Eman Namati
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Co-first authors. These authors contributed equally to this work
| | - William C. Warger
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Co-first authors. These authors contributed equally to this work
| | - Carolin I. Unglert
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Air Liquide Centre de Recherche Claude-Delorme, Medical Gases Group, 1 Chemin de la Porte des Loges, Les-Loges-en-Josas, France
| | - Jocelyn E. Eckert
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
| | | | - Brett E. Bouma
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
| | - Guillermo J. Tearney
- Harvard Medical School and Massachusetts General Hospital, Wellman Center for Photomedicine, 40 Blossom St., BAR-714, Boston, MA 02114 USA
- Harvard-MIT Division of Health Sciences and Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- Department of Pathology, Massachusetts General Hospital, Boston, MA 02114 USA
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Alveolar recruitment during mechanical ventilation – Where are we in 2013? TRENDS IN ANAESTHESIA AND CRITICAL CARE 2013. [DOI: 10.1016/j.tacc.2013.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Cyclic recruitment of atelectasis – Are there implications for our clinical practice? TRENDS IN ANAESTHESIA AND CRITICAL CARE 2013. [DOI: 10.1016/j.tacc.2013.02.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Higher Frequency Ventilation Attenuates Lung Injury during High-frequency Oscillatory Ventilation in Sheep Models of Acute Respiratory Distress Syndrome. Anesthesiology 2013; 119:398-411. [DOI: 10.1097/aln.0b013e31829419a6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Abstract
Background:
High-frequency oscillatory ventilation (HFOV) at higher frequencies minimizes the tidal volume. However, whether increased frequencies during HFOV can reduce ventilator-induced lung injury remains unknown.
Methods:
After the induction of acute respiratory distress syndrome in the model by repeated lavages, 24 adult sheep were randomly divided into four groups (n = 6): three HFOV groups (3, 6, and 9 Hz) and one conventional mechanical ventilation (CMV) group. Standard lung recruitments were performed in all groups until optimal alveolar recruitment was reached. After lung recruitment, the optimal mean airway pressure or positive end-expiratory pressure was determined with decremental pressure titration, 2 cm H2O every 10 min. Animals were ventilated for 4 h.
Results:
After lung recruitment, sustained improvements in gas exchange and compliance were observed in all groups. Compared with the HFOV-3 Hz and CMV groups, the transpulmonary pressure and tidal volumes were statistically significantly lower in the HFOV-9 Hz group. The lung injury scores and wet/dry weight ratios were significantly reduced in the HFOV-9 Hz group compared with the HFOV-3 Hz and CMV groups. Expression of interleukin-1β and interleukin-6 in the lung tissue, decreased significantly in the HFOV-9 Hz group compared with the HFOV-3 Hz and CMV groups. Malondialdehyde expression and myeloperoxidase activity in lung tissues in the HFOV-9 Hz group decreased significantly, compared with the HFOV-3 Hz and CMV groups.
Conclusion:
The use of HFOV at 9 Hz minimizes lung stress and tidal volumes, resulting in less lung injury and reduced levels of inflammatory mediators compared with the HFOV-3 Hz and CMV conditions.
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Weibel ER, Nieman GF, Gatto LA, Frazer DG, Schittny JC, Woods JC, Conradi MS, Yablonskiy DA. Commentaries on viewpoint: unresolved mysteries. J Appl Physiol (1985) 2013; 113:1948-9. [PMID: 23243296 DOI: 10.1152/japplphysiol.01203.2012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Ewald R Weibel
- Emeritus Professor Institute of Anatomy, University of Berne
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Christley S, Emr B, Ghosh A, Satalin J, Gatto L, Vodovotz Y, Nieman GF, An G. Bayesian inference of the lung alveolar spatial model for the identification of alveolar mechanics associated with acute respiratory distress syndrome. Phys Biol 2013; 10:036008. [PMID: 23598859 DOI: 10.1088/1478-3975/10/3/036008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Acute respiratory distress syndrome (ARDS) is acute lung failure secondary to severe systemic inflammation, resulting in a derangement of alveolar mechanics (i.e. the dynamic change in alveolar size and shape during tidal ventilation), leading to alveolar instability that can cause further damage to the pulmonary parenchyma. Mechanical ventilation is a mainstay in the treatment of ARDS, but may induce mechano-physical stresses on unstable alveoli, which can paradoxically propagate the cellular and molecular processes exacerbating ARDS pathology. This phenomenon is called ventilator induced lung injury (VILI), and plays a significant role in morbidity and mortality associated with ARDS. In order to identify optimal ventilation strategies to limit VILI and treat ARDS, it is necessary to understand the complex interplay between biological and physical mechanisms of VILI, first at the alveolar level, and then in aggregate at the whole-lung level. Since there is no current consensus about the underlying dynamics of alveolar mechanics, as an initial step we investigate the ventilatory dynamics of an alveolar sac (AS) with the lung alveolar spatial model (LASM), a 3D spatial biomechanical representation of the AS and its interaction with airflow pressure and the surface tension effects of pulmonary surfactant. We use the LASM to identify the mechanical ramifications of alveolar dynamics associated with ARDS. Using graphical processing unit parallel algorithms, we perform Bayesian inference on the model parameters using experimental data from rat lung under control and Tween-induced ARDS conditions. Our results provide two plausible models that recapitulate two fundamental hypotheses about volume change at the alveolar level: (1) increase in alveolar size through isotropic volume change, or (2) minimal change in AS radius with primary expansion of the mouth of the AS, with the implication that the majority of change in lung volume during the respiratory cycle occurs in the alveolar ducts. These two model solutions correspond to significantly different mechanical properties of the tissue, and we discuss the implications of these different properties and the requirements for new experimental data to discriminate between the hypotheses.
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Affiliation(s)
- Scott Christley
- Department of Surgery, University of Chicago, Chicago, IL 60637, USA
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Díaz F, Erranz B, Donoso A, Carvajal C, Salomón T, Torres M, Cruces P. Surfactant deactivation in a pediatric model induces hypovolemia and fluid shift to the extravascular lung compartment. Paediatr Anaesth 2013; 23:250-7. [PMID: 23043489 DOI: 10.1111/pan.12037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/19/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND Surfactant deficiency is the pivotal abnormality in Neonatal and Acute Respiratory Distress Syndrome. Surfactant deactivation can produce hypoxemia, loss of lung compliance, and pulmonary edema, but its circulatory consequences are less understood. OBJECTIVE To describe the sequential hemodynamic changes and pulmonary edema formation after surfactant deactivation in piglets. METHODS Surfactant deactivation was induced by tracheal instillation of polysorbate 20 in 15 anesthetized and mechanically ventilated Large White piglets. The hemodynamic consequences of surfactant deactivation were assessed at 30, 120, and 240 min by transpulmonary thermodilution and traditional methods. RESULTS Surfactant deactivation caused hypoxemia, reduced lung compliance, and progressively increased lung water content (P < 0.01). Early hypovolemia was observed, with reductions of the global end-diastolic volume and stroke volume (P < 0.05). Reduced cardiac output was observed at the end of the study (P < 0.05). Standard monitoring was unable to detect these early preload alterations. Surprisingly, the bronchoalveolar protein content was greatly increased at the end of the study compared with baseline levels (P < 0.01). This finding was inconsistent with the notion that the pulmonary edema induced by surfactant deactivation was exclusively caused by high surface tension. CONCLUSIONS Hypovolemia develops early after surfactant deactivation, in part due to the resulting fluid shift from the intravascular compartment to the lungs.
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Affiliation(s)
- Franco Díaz
- Área de Cuidados Críticos, Hospital Padre Hurtado, Santiago, Chile
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