101
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Smith BJ. Strain heterogeneity in the injured lung: cause or consequence? J Appl Physiol (1985) 2016; 121:1363-1364. [PMID: 27633744 DOI: 10.1152/japplphysiol.00818.2016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 09/14/2016] [Indexed: 11/22/2022] Open
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102
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Cressoni M, Chiumello D. Transpulmonary pressure during high-frequency oscillation ventilation: Is it the culprit? Ann Intensive Care 2016; 6:86. [PMID: 27620876 PMCID: PMC5020035 DOI: 10.1186/s13613-016-0191-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 08/31/2016] [Indexed: 11/12/2022] Open
Affiliation(s)
- M Cressoni
- Dipartimento di Fisiopatologia Medico Chirurgica e dei Trapianti, Università degli Studi di Milano, Milan, Italy
| | - Davide Chiumello
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy. .,Dipartimento di Emergenza-Urgenza, ASST Santi Paolo e Carlo, Milan, Italy.
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103
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Guervilly C, Forel JM, Hraiech S, Roch A, Talmor D, Papazian L. Effect of high-frequency oscillatory ventilation on esophageal and transpulmonary pressures in moderate-to-severe acute respiratory distress syndrome. Ann Intensive Care 2016; 6:84. [PMID: 27577052 PMCID: PMC5005229 DOI: 10.1186/s13613-016-0181-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/10/2016] [Indexed: 12/02/2022] Open
Abstract
Background High-frequency oscillatory ventilation (HFOV) has not been shown to be beneficial in the management of moderate-to-severe acute respiratory distress syndrome (ARDS). There is uncertainty about the actual pressure applied into the lung during HFOV. We therefore performed a study to compare the transpulmonary pressure (PL) during conventional mechanical ventilation (CMV) and different levels of mean airway pressure (mPaw) during HFOV. Methods This is a prospective randomized crossover study in a university teaching hospital. An esophageal balloon catheter was used to measure esophageal pressures (Pes) at end inspiration and end expiration and to calculate PL. Measurements were taken during ventilation with CMV (CMVpre) after which patients were switched to HFOV with three 1-h different levels of mPaw set at +5, +10 and +15 cm H2O above the mean airway pressure measured during CMV. Patients were thereafter switched back to CMV (CMVpost). Results Ten patients with moderate-to-severe ARDS were included. We demonstrated a linear increase in Pes and PL with the increase in mPaw during HFOV. Contrary to CMV, PL was always positive during HFOV whatever the level of mPaw applied but not associated with improvement in oxygenation. We found significant correlations between mPaw and Pes. Conclusion HFOV with high level of mPaw increases transpulmonary pressures without improvement in oxygenation.
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Affiliation(s)
- Christophe Guervilly
- Aix-Marseille Univ, APHM, URMITE UMR CNRS 7278, Hôpital Nord, Réanimation des Détresses Respiratoires et Infections Sévères, Marseille, France.
| | - Jean-Marie Forel
- Aix-Marseille Univ, APHM, URMITE UMR CNRS 7278, Hôpital Nord, Réanimation des Détresses Respiratoires et Infections Sévères, Marseille, France
| | - Sami Hraiech
- Aix-Marseille Univ, APHM, URMITE UMR CNRS 7278, Hôpital Nord, Réanimation des Détresses Respiratoires et Infections Sévères, Marseille, France
| | - Antoine Roch
- Aix-Marseille Univ, APHM, URMITE UMR CNRS 7278, Hôpital Nord, Réanimation des Détresses Respiratoires et Infections Sévères, Marseille, France.,Service d'Accueil des Urgences, APHM, Hôpital Nord, Marseille, France
| | - Daniel Talmor
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, 330 Brookline Ave, Boston, MA, USA
| | - Laurent Papazian
- Aix-Marseille Univ, APHM, URMITE UMR CNRS 7278, Hôpital Nord, Réanimation des Détresses Respiratoires et Infections Sévères, Marseille, France
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104
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Bedside assessment of the effects of positive end-expiratory pressure on lung inflation and recruitment by the helium dilution technique and electrical impedance tomography. Intensive Care Med 2016; 42:1576-1587. [DOI: 10.1007/s00134-016-4467-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 07/28/2016] [Indexed: 11/26/2022]
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105
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Formenti P, Umbrello M, Graf J, Adams AB, Dries DJ, Marini JJ. Reliability of transpulmonary pressure-time curve profile to identify tidal recruitment/hyperinflation in experimental unilateral pleural effusion. J Clin Monit Comput 2016; 31:783-791. [PMID: 27438965 DOI: 10.1007/s10877-016-9908-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Accepted: 07/14/2016] [Indexed: 10/21/2022]
Abstract
The stress index (SI) is a parameter that characterizes the shape of the airway pressure-time profile (P/t). It indicates the slope progression of the curve, reflecting both lung and chest wall properties. The presence of pleural effusion alters the mechanical properties of the respiratory system decreasing transpulmonary pressure (Ptp). We investigated whether the SI computed using Ptp tracing would provide reliable insight into tidal recruitment/overdistention during the tidal cycle in the presence of unilateral effusion. Unilateral pleural effusion was simulated in anesthetized, mechanically ventilated pigs. Respiratory system mechanics and thoracic computed tomography (CT) were studied to assess P/t curve shape and changes in global lung aeration. SI derived from airway pressure (Paw) was compared with that calculated by Ptp under the same conditions. These results were themselves compared with quantitative CT analysis as a gold standard for tidal recruitment/hyperinflation. Despite marked changes in tidal recruitment, mean values of SI computed either from Paw or Ptp were remarkably insensitive to variations of PEEP or condition. After the instillation of effusion, SI indicates a preponderant over-distension effect, not detected by CT. After the increment in PEEP level, the extent of CT-determined tidal recruitment suggest a huge recruitment effect of PEEP as reflected by lung compliance. Both SI in this case were unaffected. We showed that the ability of SI to predict tidal recruitment and overdistension was significantly reduced in a model of altered chest wall-lung relationship, even if the parameter was computed from the Ptp curve profile.
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Affiliation(s)
- P Formenti
- Pulmonary Research Laboratory, Regions Hospital, St Paul, MN, USA. .,Dipartimento di Anestesiologia e Terapia Intensiva, Azienda Opsedaliera San Paolo - Polo Universitario, Univeristà degli Studi di Milano, Via A. Di Rudinì, 8, 20142, Milan, Italy.
| | - M Umbrello
- Dipartimento di Anestesiologia e Terapia Intensiva, Azienda Opsedaliera San Paolo - Polo Universitario, Univeristà degli Studi di Milano, Via A. Di Rudinì, 8, 20142, Milan, Italy
| | - J Graf
- Pulmonary Research Laboratory, Regions Hospital, St Paul, MN, USA.,Departamento de Paciente Critico, Clinica Alemana de Santiago, Facultad de Medicina Clinica Alemana, Universidad del Desarrollo, Vitacura, Santiago, Chile
| | - A B Adams
- Pulmonary Research Laboratory, Regions Hospital, St Paul, MN, USA
| | - D J Dries
- Department of Surgical Services, HealthPartners Medical Group, University of Minnesota, Minneapolis/St. Paul, MN, USA
| | - J J Marini
- Pulmonary Research Laboratory, Regions Hospital, St Paul, MN, USA
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106
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El-Dash SA, Borges JB, Costa ELV, Tucci MR, Ranzani OT, Caramez MP, Carvalho CRR, Amato MBP. There is no cephalocaudal gradient of computed tomography densities or lung behavior in supine patients with acute respiratory distress syndrome. Acta Anaesthesiol Scand 2016; 60:767-79. [PMID: 26806959 DOI: 10.1111/aas.12690] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2015] [Accepted: 12/15/2015] [Indexed: 01/11/2023]
Abstract
BACKGROUND There is debate whether pressure transmission within the lungs and alveolar collapse follow a hydrostatic pattern or the compression exerted by the weight of the heart and the diaphragm causes collapse localized in the areas adjacent to these structures. The second hypothesis proposes the existence of a cephalocaudal gradient in alveolar collapse. We aimed to define whether or not lung density and collapse follow a 'liquid-like' pattern with homogeneous isogravitational layers along the cephalocaudal axis in acute respiratory distress syndrome lungs. METHODS Acute respiratory distress syndrome patients were submitted to full lung computed tomography scans at positive end-expiratory pressure (PEEP) zero (before) and 25 cmH2 O after a maximum-recruitment maneuver. PEEP was then decreased by 2 cmH2 O every 4 min, and a semi-complete scan performed at the end of each PEEP step. RESULTS Lung densities were homogeneous within each lung layer. Lung density increased along the ventrodorsal axis toward the dorsal region (β = 0.49, P < 0.001), while there was no increase, but rather a slight decrease, toward the diaphragm along the cephalocaudal axis and toward the heart. Higher PEEP attenuated density gradients. At PEEP 18 cmH2 O, dependent lung regions started to collapse massively, while best compliance was only reached at a lower PEEP. CONCLUSIONS We could not detect cephalocaudal gradients in lung densities or in alveolar collapse. Likely, external pressures applied on the lung by the chest wall, organs, and effusions are transmitted throughout the lung in a hydrostatic pattern with homogeneous consequences at each isogravitational layer. A single cross-sectional image of the lung could fully represent the heterogeneous mechanical properties of dependent and non-dependent lung regions.
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Affiliation(s)
- S. A. El-Dash
- Pulmonary Division; Heart Institute (InCor); Hospital das Clínicas; University of São Paulo; São Paulo Brazil
| | - J. B. Borges
- Pulmonary Division; Heart Institute (InCor); Hospital das Clínicas; University of São Paulo; São Paulo Brazil
- Section of Anaesthesiology & Critical Care; Department of Surgical Sciences; Hedenstierna Laboratory; Uppsala University; Uppsala Sweden
| | - E. L. V. Costa
- Pulmonary Division; Heart Institute (InCor); Hospital das Clínicas; University of São Paulo; São Paulo Brazil
- Research and Education Institute of Hospital Sírio Libanês; São Paulo Brazil
| | - M. R. Tucci
- Pulmonary Division; Heart Institute (InCor); Hospital das Clínicas; University of São Paulo; São Paulo Brazil
| | - O. T. Ranzani
- Pulmonary Division; Heart Institute (InCor); Hospital das Clínicas; University of São Paulo; São Paulo Brazil
| | - M. P. Caramez
- Pulmonary Division; Heart Institute (InCor); Hospital das Clínicas; University of São Paulo; São Paulo Brazil
| | - C. R. R. Carvalho
- Pulmonary Division; Heart Institute (InCor); Hospital das Clínicas; University of São Paulo; São Paulo Brazil
| | - M. B. P. Amato
- Pulmonary Division; Heart Institute (InCor); Hospital das Clínicas; University of São Paulo; São Paulo Brazil
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107
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Prodhan P, Noviski N. Pediatric Acute Hypoxemic Respiratory Failure: Management of Oxygenation. J Intensive Care Med 2016; 19:140-53. [PMID: 15154995 DOI: 10.1177/0885066604263859] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Acute hypoxemic respiratory failure (AHRF) is one of the hallmarks of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), which are caused by an inflammatory process initiated by any of a number of potential systemic and/or pulmonary insults that result in heterogeneous disruption of the capillary-pithelial interface. In these critically sick patients, optimizing the management of oxygenation is crucial. Physicians managing pediatric patients with ALI or ARDS are faced with a complex array of options influencing oxygenation. Certain treatment strategies can influence clinical outcomes, such as a lung protective ventilation strategy that specifies a low tidal volume (6 mL/kg) and a plateau pressure limit (30 cm H2O). Other strategies such as different levels of positive end expiratory pressure, altered inspiration to expiration time ratios, recruitment maneuvers, prone positioning, and extraneous gases or drugs may also affect clinical outcomes. This article reviews state-of-the-art strategies on the management of oxygenation in acute hypoxemic respiratory failure in children.
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Affiliation(s)
- Parthak Prodhan
- Division of Pediatric Critical Care Medicine, MassGeneral Hospital for Children, Boston, Massachusetts 02114, USA
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108
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Esophageal and transpulmonary pressure in the clinical setting: meaning, usefulness and perspectives. Intensive Care Med 2016; 42:1360-73. [PMID: 27334266 DOI: 10.1007/s00134-016-4400-x] [Citation(s) in RCA: 291] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 05/17/2016] [Indexed: 12/18/2022]
Abstract
PURPOSE Esophageal pressure (Pes) is a minimally invasive advanced respiratory monitoring method with the potential to guide management of ventilation support and enhance specific diagnoses in acute respiratory failure patients. To date, the use of Pes in the clinical setting is limited, and it is often seen as a research tool only. METHODS This is a review of the relevant technical, physiological and clinical details that support the clinical utility of Pes. RESULTS After appropriately positioning of the esophageal balloon, Pes monitoring allows titration of controlled and assisted mechanical ventilation to achieve personalized protective settings and the desired level of patient effort from the acute phase through to weaning. Moreover, Pes monitoring permits accurate measurement of transmural vascular pressure and intrinsic positive end-expiratory pressure and facilitates detection of patient-ventilator asynchrony, thereby supporting specific diagnoses and interventions. Finally, some Pes-derived measures may also be obtained by monitoring electrical activity of the diaphragm. CONCLUSIONS Pes monitoring provides unique bedside measures for a better understanding of the pathophysiology of acute respiratory failure patients. Including Pes monitoring in the intensivist's clinical armamentarium may enhance treatment to improve clinical outcomes.
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109
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How much esophageal pressure-guided end-expiratory transpulmonary pressure is sufficient to maintain lung recruitment in lavage-induced lung injury? J Trauma Acute Care Surg 2016; 80:302-7. [PMID: 26517781 DOI: 10.1097/ta.0000000000000900] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
BACKGROUND Because of limitations of the esophageal balloon technique, the value of using esophageal pressure (Pes)-guided end-expiratory transpulmonary pressure (PL-exp) to maintain lung recruitment in adult respiratory distress syndrome is controversial. This study aimed to investigate whether tailoring PL-exp to greater than 0 was enough to maintain lung recruitment. METHODS Ten pigs with severe lavage-induced lung injury were mechanically ventilated in a decremental positive end-expiratory pressure (PEEP) trial that was reduced from 20 to 6 cm H2O after full-lung recruitment. Respiratory mechanics, blood gases, hemodynamic data, and whole-lung computed tomography scans were recorded at each PEEP level. Open-lung PEEP (OL-PEEP) was determined by computed tomography, while Pes-guided PEEP (Pes-PEEP) was to maintain PL-exp greater than 0. RESULTS OL-PEEP was higher than Pes-PEEP, which induced a higher PL-exp at OL-PEEP than at Pes-PEEP (4.6 [1.6] cm H2O vs. 1.2 [0.6] cm H2O, p < 0.001). Compared with OL-PEEP, the nonaerated lung region was significantly increased at Pes-PEEP. Superimposed pressure (SP) of the lung tissue between the esophageal plane and the dorsal level was higher at Pes-PEEP than at OL-PEEP, whereas PL-exp at the dorsal level was lower at Pes-PEEP than at OL-PEEP (-1.5 [0.7] cm H2O vs. 2.5 [1.5] cm H2O, p < 0.001). The SP correlated with PL-exp at the dorsal level and the nonaerated lung region. CONCLUSION In this surfactant-depleted model, maintaining PL-exp just greater than 0 using Pes was unable to maintain lung recruitment; this was partly caused by a lack of compensation for the increased SP between the esophageal plane and the dorsal level.
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110
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Donoso A, Arriagada D, Contreras D, Ulloa D, Neumann M. [Respiratory monitoring of pediatric patients in the Intensive Care Unit]. BOLETIN MEDICO DEL HOSPITAL INFANTIL DE MEXICO 2016; 73:149-165. [PMID: 29421202 DOI: 10.1016/j.bmhimx.2016.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 01/29/2016] [Accepted: 02/02/2016] [Indexed: 06/08/2023] Open
Abstract
Respiratory monitoring plays an important role in the care of children with acute respiratory failure. Therefore, its proper use and correct interpretation (recognizing which signals and variables should be prioritized) should help to a better understanding of the pathophysiology of the disease and the effects of therapeutic interventions. In addition, ventilated patient monitoring, among other determinations, allows to evaluate various parameters of respiratory mechanics, know the status of the different components of the respiratory system and guide the adjustments of ventilatory therapy. In this update, the usefulness of several techniques of respiratory monitoring including conventional respiratory monitoring and more recent methods are described. Moreover, basic concepts of mechanical ventilation, their interpretation and how the appropriate analysis of the information obtained can cause an impact on the clinical management of the patient are defined.
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Affiliation(s)
| | | | - Dina Contreras
- Hospital Clínico Metropolitano La Florida, Santiago, Chile
| | - Daniela Ulloa
- Hospital Clínico Metropolitano La Florida, Santiago, Chile
| | - Megan Neumann
- Hospital Clínico Metropolitano La Florida, Santiago, Chile
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111
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Gattinoni L, Quintel M. How ARDS should be treated. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2016; 20:86. [PMID: 27048605 PMCID: PMC4822276 DOI: 10.1186/s13054-016-1268-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The Berlin definition criteria applied at positive end-expiratory pressure (PEEP) 5 cm H2O reasonably predict lung edema and recruitabilty. To maintain viable gas exchange, the mechanical ventilation becomes progressively more risky going from mild to severe acute respiratory distress syndrome (ARDS). Tidal volume, driving pressure, flow, and respiratory rate have been identified as causes of ventilation-induced lung injury. Taken together, they represent the mechanical power applied to the lung parenchyma. In an inhomogeneous lung, stress risers locally increase the applied mechanical power. Increasing lung homogeneity by PEEP and prone position decreases the harm of mechanical ventilation, particularly in severe ARDS.
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Affiliation(s)
- Luciano Gattinoni
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straβe 40, 37075, Göttingen, Germany.
| | - Michael Quintel
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Straβe 40, 37075, Göttingen, Germany
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112
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Jauncey-Cooke J, Schibler A, Bogossian F, Gibbons K, Grant CA, East CE. Lung recruitment manoeuvres in mechanically ventilated children for reducing respiratory morbidity. Hippokratia 2016. [DOI: 10.1002/14651858.cd008866.pub2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | - Andreas Schibler
- Mater Children’s Hospital; Paediatric Critical Care Research Group; South Brisbane Queensland Australia 4101
| | - Fiona Bogossian
- School of Nursing and Midwifery; The University of Queensland; Herston Australia
| | - Kristen Gibbons
- Mater Research Institute; South Brisbane Queensland Australia 4101
| | - Caroline A Grant
- Mater Children's Hospital; Paediatric Intensive Care Unit; Raymond Terrace South Brisbane Queensland Australia 4001
| | - Christine E East
- Monash University/Monash Health; School of Nursing and Midwifery/Maternity Services; 246 Clayton Road Clayton Victoria Australia 3168
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113
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Physiological Effects of the Open Lung Approach in Patients with Early, Mild, Diffuse Acute Respiratory Distress Syndrome: An Electrical Impedance Tomography Study. Anesthesiology 2016; 123:1113-21. [PMID: 26397017 DOI: 10.1097/aln.0000000000000862] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND To test the hypothesis that in early, mild, acute respiratory distress syndrome (ARDS) patients with diffuse loss of aeration, the application of the open lung approach (OLA) would improve homogeneity in lung aeration and lung mechanics, without affecting hemodynamics. METHODS Patients were ventilated according to the ARDS Network protocol at baseline (pre-OLA). OLA consisted in a recruitment maneuver followed by a decremental positive end-expiratory pressure trial. Respiratory mechanics, gas exchange, electrical impedance tomography (EIT), cardiac index, and stroke volume variation were measured at baseline and 20 min after OLA implementation (post-OLA). Esophageal pressure was used for lung and chest wall elastance partitioning. The tomographic lung image obtained at the fifth intercostal space by EIT was divided in two ventral and two dorsal regions of interest (ROIventral and ROIDorsal). RESULTS Fifteen consecutive patients were studied. The OLA increased arterial oxygen partial pressure/inspired oxygen fraction from 216 ± 13 to 311 ± 19 mmHg (P < 0.001) and decreased elastance of the respiratory system from 29.4 ± 3 cm H2O/l to 23.6 ± 1.7 cm H2O/l (P < 0.01). The driving pressure (airway opening plateau pressure - total positive end-expiratory pressure) decreased from 17.9 ± 1.5 cm H2O pre-OLA to 15.4 ± 2.1 post-OLA (P < 0.05). The tidal volume fraction reaching the dorsal ROIs increased, and consequently the ROIVentral/Dorsal impedance tidal variation decreased from 2.01 ± 0.36 to 1.19 ± 0.1 (P < 0.01). CONCLUSIONS The OLA decreases the driving pressure and improves the oxygenation and lung mechanics in patients with early, mild, diffuse ARDS. EIT is useful to assess the impact of OLA on regional tidal volume distribution.
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114
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Abstract
Considerable progress has been made recently in the understanding of how best to accomplish safe and effective ventilation of patients with acute lung injury. Mechanical and nonmechanical factors contribute to causation of ventilator-associated lung injury. Intervention timing helps determine the therapeutic efficacy and outcome, and the stage and severity of the disease process may determine the patient's vulnerability as well as an intervention's value. Reducing oxygen consumption and ventilatory demands are key to a successful strategy for respiratory support of acute respiratory distress syndrome. Results from major clinical trials can be understood against the background of the complex physiology of ventilator-induced lung injury.
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Affiliation(s)
- John J Marini
- University of Minnesota, Minneapolis/St. Paul, MN, USA
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115
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Takeuchi M, Tachibana K. Mechanical ventilation for ARDS patients--for a better understanding of the 2012 Surviving Sepsis Campaign Guidelines. Cardiovasc Hematol Disord Drug Targets 2015; 15:41-5. [PMID: 25567337 PMCID: PMC4428140 DOI: 10.2174/1871529x15666150108113853] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 09/20/2014] [Accepted: 10/10/2014] [Indexed: 12/29/2022]
Abstract
The mortality rate among patients suffering acute respiratory distress syndrome (ARDS) remains high despite implementation at clinical centers of the lung protective ventilatory strategies recommended by the International Guidelines for Management of Severe Sepsis and Septic Shock, 2012. This suggests that such strategies are still sub-optimal for some ARDS patients. For these patients, tailored use of ventilator settings should be considered, including: further reduction of tidal volumes, administration of neuromuscular blocking agents if the patient’s spontaneous breathing is incompatible with mechanical ventilation, and adjusting positive end-expiratory pressure (PEEP) settings based on transpulmonary pressure levels.
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Affiliation(s)
| | - Kazuya Tachibana
- Department of Intensive Care Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, 840 Murodocho, Izumi, Osaka, 594-1101, Japan.
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116
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Kollisch-Singule M, Emr B, Jain SV, Andrews P, Satalin J, Liu J, Porcellio E, Kenyon V, Wang G, Marx W, Gatto LA, Nieman GF, Habashi NM. The effects of airway pressure release ventilation on respiratory mechanics in extrapulmonary lung injury. Intensive Care Med Exp 2015; 3:35. [PMID: 26694915 PMCID: PMC4688284 DOI: 10.1186/s40635-015-0071-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 12/13/2015] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Lung injury is often studied without consideration for pathologic changes in the chest wall. In order to reduce the incidence of lung injury using preemptive mechanical ventilation, it is important to recognize the influence of altered chest wall mechanics on disease pathogenesis. In this study, we hypothesize that airway pressure release ventilation (APRV) may be able to reduce the chest wall elastance associated with an extrapulmonary lung injury model as compared with low tidal volume (LVt) ventilation. METHODS Female Yorkshire pigs were anesthetized and instrumented. Fecal peritonitis was established, and the superior mesenteric artery was clamped for 30 min to induce an ischemia/reperfusion injury. Immediately following injury, pigs were randomized into (1) LVt (n = 3), positive end-expiratory pressure (PEEP) 5 cmH2O, V t 6 cc kg(-1), FiO2 21 %, and guided by the ARDSnet protocol or (2) APRV (n = 3), P High 16-22 cmH2O, P Low 0 cmH2O, T High 4.5 s, T Low set to terminate the peak expiratory flow at 75 %, and FiO2 21 %. Pigs were monitored continuously for 48 h. Lung samples and bronchoalveolar lavage fluid were collected at necropsy. RESULTS LVt resulted in mild acute respiratory distress syndrome (ARDS) (PaO2/FiO2 = 226.2 ± 17.1 mmHg) whereas APRV prevented ARDS (PaO2/FiO2 = 465.7 ± 66.5 mmHg; p < 0.05). LVt had a reduced surfactant protein A concentration and increased histologic injury as compared with APRV. The plateau pressure in APRV (34.3 ± 0.9 cmH2O) was significantly greater than LVt (22.2 ± 2.0 cmH2O; p < 0.05) yet transpulmonary pressure between groups was similar (p > 0.05). This was because the pleural pressure was significantly lower in LVt (7.6 ± 0.5 cmH2O) as compared with APRV (17.4 ± 3.5 cmH2O; p < 0.05). Finally, the elastance of the lung, chest wall, and respiratory system were all significantly greater in LVt as compared with APRV (all p < 0.05). CONCLUSIONS APRV preserved surfactant and lung architecture and maintenance of oxygenation. Despite the greater plateau pressure and tidal volumes in the APRV group, the transpulmonary pressure was similar to that of LVt. Thus, the majority of the plateau pressure in the APRV group was distributed as pleural pressure in this extrapulmonary lung injury model. APRV maintained a normal lung elastance and an open, homogeneously ventilated lung without increasing lung stress.
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Affiliation(s)
- Michaela Kollisch-Singule
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Bryanna Emr
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Sumeet V Jain
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Penny Andrews
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Joshua Satalin
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Jiao Liu
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Elizabeth Porcellio
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Van Kenyon
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Guirong Wang
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - William Marx
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Louis A Gatto
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
- Department of Biological Sciences, SUNY Cortland, Cortland, NY, USA.
| | - Gary F Nieman
- Department of Surgery, SUNY Upstate Medical University, 750 E. Adams Street, Syracuse, NY, 13210, USA.
| | - Nader M Habashi
- Department of Trauma Critical Care Medicine, R Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, MD, USA.
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Intraoperative protective mechanical ventilation for prevention of postoperative pulmonary complications: a comprehensive review of the role of tidal volume, positive end-expiratory pressure, and lung recruitment maneuvers. Anesthesiology 2015; 123:692-713. [PMID: 26120769 DOI: 10.1097/aln.0000000000000754] [Citation(s) in RCA: 244] [Impact Index Per Article: 27.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Postoperative pulmonary complications are associated with increased morbidity, length of hospital stay, and mortality after major surgery. Intraoperative lung-protective mechanical ventilation has the potential to reduce the incidence of postoperative pulmonary complications. This review discusses the relevant literature on definition and methods to predict the occurrence of postoperative pulmonary complication, the pathophysiology of ventilator-induced lung injury with emphasis on the noninjured lung, and protective ventilation strategies, including the respective roles of tidal volumes, positive end-expiratory pressure, and recruitment maneuvers. The authors propose an algorithm for protective intraoperative mechanical ventilation based on evidence from recent randomized controlled trials.
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Cressoni M, Chiumello D, Chiurazzi C, Brioni M, Algieri I, Gotti M, Nikolla K, Massari D, Cammaroto A, Colombo A, Cadringher P, Carlesso E, Benti R, Casati R, Zito F, Gattinoni L. Lung inhomogeneities, inflation and [18F]2-fluoro-2-deoxy-D-glucose uptake rate in acute respiratory distress syndrome. Eur Respir J 2015; 47:233-42. [DOI: 10.1183/13993003.00885-2015] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/05/2015] [Indexed: 01/17/2023]
Abstract
The aim of the study was to determine the size and location of homogeneous inflamed/noninflamed and inhomogeneous inflamed/noninflamed lung compartments and their association with acute respiratory distress syndrome (ARDS) severity.In total, 20 ARDS patients underwent 5 and 45 cmH2O computed tomography (CT) scans to measure lung recruitability. [18F]2-fluoro-2-deoxy-d-glucose ([18F]FDG) uptake and lung inhomogeneities were quantified with a positron emission tomography-CT scan at 10 cmH2O. We defined four compartments with normal/abnormal [18F]FDG uptake and lung homogeneity.The homogeneous compartment with normal [18F]FDG uptake was primarily composed of well-inflated tissue (80±16%), double-sized in nondependent lung (32±27% versus 16±17%, p<0.0001) and decreased in size from mild, moderate to severe ARDS (33±14%, 26±20% and 5±9% of the total lung volume, respectively, p=0.05). The homogeneous compartment with high [18F]FDG uptake was similarly distributed between the dependent and nondependent lung. The inhomogeneous compartment with normal [18F]FDG uptake represented 4% of the lung volume. The inhomogeneous compartment with high [18F]FDG uptake was preferentially located in the dependent lung (21±10% versus 12±10%, p<0.0001), mostly at the open/closed interfaces and related to recruitability (r2=0.53, p<0.001).The homogeneous lung compartment with normal inflation and [18F]FDG uptake decreases with ARDS severity, while the inhomogeneous poorly/not inflated compartment increases. Most of the lung inhomogeneities are inflamed. A minor fraction of healthy tissue remains in severe ARDS.
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Effects of ultraprotective ventilation, extracorporeal carbon dioxide removal, and spontaneous breathing on lung morphofunction and inflammation in experimental severe acute respiratory distress syndrome. Anesthesiology 2015; 122:631-46. [PMID: 25371037 DOI: 10.1097/aln.0000000000000504] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND To investigate the role of ultraprotective mechanical ventilation (UP-MV) and extracorporeal carbon dioxide removal with and without spontaneous breathing (SB) to improve respiratory function and lung protection in experimental severe acute respiratory distress syndrome. METHODS Severe acute respiratory distress syndrome was induced by saline lung lavage and mechanical ventilation (MV) with higher tidal volume (VT) in 28 anesthetized pigs (32.8 to 52.5 kg). Animals (n = 7 per group) were randomly assigned to 6 h of MV (airway pressure release ventilation) with: (1) conventional P-MV with VT ≈6 ml/kg (P-MVcontr); (2) UP-MV with VT ≈3 ml/kg (UP-MVcontr); (3) UP-MV with VT ≈3 ml/kg and SB (UP-MVspont); and (4) UP-MV with VT ≈3 ml/kg and pressure supported SB (UP-MVPS). In UP-MV groups, extracorporeal carbon dioxide removal was used. RESULTS The authors found that: (1) UP-MVcontr reduced diffuse alveolar damage score in dorsal lung zones (median[interquartile]) (12.0 [7.0 to 16.8] vs. 22.5 [13.8 to 40.8]), but worsened oxygenation and intrapulmonary shunt, compared to P-MVcontr; (2) UP-MVspont and UP-MVPS improved oxygenation and intrapulmonary shunt, and redistributed ventilation towards dorsal areas, as compared to UP-MVcontr; (3) compared to P-MVcontr, UP-MVcontr and UP-MVspont, UP-MVPS yielded higher levels of tumor necrosis factor-α (6.9 [6.5 to 10.1] vs. 2.8 [2.2 to 3.0], 3.6 [3.0 to 4.7] and 4.0 [2.8 to 4.4] pg/mg, respectively) and interleukin-8 (216.8 [113.5 to 343.5] vs. 59.8 [45.3 to 66.7], 37.6 [18.8 to 52.0], and 59.5 [36.1 to 79.7] pg/mg, respectively) in dorsal lung zones. CONCLUSIONS In this model of severe acute respiratory distress syndrome, MV with VT ≈3 ml/kg and extracorporeal carbon dioxide removal without SB slightly reduced lung histologic damage, but not inflammation, as compared to MV with VT = 4 to 6 ml/kg. During UP-MV, pressure supported SB increased lung inflammation.
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Smith BJ, Lundblad LKA, Kollisch-Singule M, Satalin J, Nieman G, Habashi N, Bates JHT. Predicting the response of the injured lung to the mechanical breath profile. J Appl Physiol (1985) 2015; 118:932-40. [PMID: 25635004 PMCID: PMC4385881 DOI: 10.1152/japplphysiol.00902.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 01/22/2015] [Indexed: 11/22/2022] Open
Abstract
Mechanical ventilation is a crucial component of the supportive care provided to patients with acute respiratory distress syndrome. Current practice stipulates the use of a low tidal volume (VT) of 6 ml/kg ideal body weight, the presumptive notion being that this limits overdistension of the tissues and thus reduces volutrauma. We have recently found, however, that airway pressure release ventilation (APRV) is efficacious at preventing ventilator-induced lung injury, yet APRV has a very different mechanical breath profile compared with conventional low-VT ventilation. To gain insight into the relative merits of these two ventilation modes, we measured lung mechanics and derecruitability in rats before and following Tween lavage. We fit to these lung mechanics measurements a computational model of the lung that accounts for both the degree of tissue distension of the open lung and the amount of lung derecruitment that takes place as a function of time. Using this model, we predicted how tissue distension, open lung fraction, and intratidal recruitment vary as a function of ventilator settings both for conventional low-VT ventilation and for APRV. Our predictions indicate that APRV is more effective at recruiting the lung than low-VT ventilation, but without causing more overdistension of the tissues. On the other hand, low-VT ventilation generally produces less intratidal recruitment than APRV. Predictions such as these may be useful for deciding on the relative benefits of different ventilation modes and thus may serve as a means for determining how to ventilate a given lung in the least injurious fashion.
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Affiliation(s)
- Bradford J Smith
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont
| | - Lennart K A Lundblad
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont
| | - Michaela Kollisch-Singule
- Department of Surgery, State University of New York Upstate Medical University, Syracuse, New York; and
| | - Joshua Satalin
- Department of Surgery, State University of New York Upstate Medical University, Syracuse, New York; and
| | - Gary Nieman
- Department of Surgery, State University of New York Upstate Medical University, Syracuse, New York; and
| | - Nader Habashi
- R. Adams Cowley Shock Trauma Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jason H T Bates
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont;
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Santos CL, Samary CDS, Fiorio Júnior PL, Santos BL, Schanaider A. Pulmonar recruitment in acute respiratory distress syndrome. What is the best strategy? Rev Col Bras Cir 2015; 42:125-9. [DOI: 10.1590/0100-69912015002010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 05/20/2014] [Indexed: 12/15/2022] Open
Abstract
Supporting patients with acute respiratory distress syndrome (ARDS), using a protective mechanical ventilation strategy characterized by low tidal volume and limitation of positive end-expiratory pressure (PEEP) is a standard practice in the intensive care unit. However, these strategies can promote lung de-recruitment, leading to the cyclic closing and reopening of collapsed alveoli and small airways. Recruitment maneuvers (RM) can be used to augment other methods, like positive end-expiratory pressure and positioning, to improve aerated lung volume. Clinical practice varies widely, and the optimal method and patient selection for recruitment maneuvers have not been determined, considerable uncertainty remaining regarding the appropriateness of RM. This review aims to discuss recent findings about the available types of RM, and compare the effectiveness, indications and adverse effects among them, as well as their impact on morbidity and mortality in ARDS patients. Recent developments include experimental and clinical evidence that a stepwise extended recruitment maneuver may cause an improvement in aerated lung volume and decrease the biological impact seen with the traditionally used sustained inflation, with less adverse effects. Prone positioning can reduce mortality in severe ARDS patients and may be an useful adjunct to recruitment maneuvers and advanced ventilatory strategies, such noisy ventilation and BIVENT, which have been useful in providing lung recruitment.
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Valentini R, Aquino-Esperanza J, Bonelli I, Maskin P, Setten M, Danze F, Attie S, Rodriguez PO. Gas exchange and lung mechanics in patients with acute respiratory distress syndrome: Comparison of three different strategies of positive end expiratory pressure selection. J Crit Care 2015; 30:334-40. [DOI: 10.1016/j.jcrc.2014.11.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 11/08/2014] [Accepted: 11/27/2014] [Indexed: 11/15/2022]
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Chest wall elastance in the estimation of the transpulmonary pressure: how should we use it? Crit Care Med 2015; 43:e53-4. [PMID: 25599501 DOI: 10.1097/ccm.0000000000000741] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Li Bassi G, Fernandez-Barat L, Saucedo L, Giunta V, Marti JD, Tavares Ranzani O, Aguilera Xiol E, Rigol M, Roca I, Muñoz L, Luque N, Esperatti M, Saco MA, Ramirez J, Vila J, Ferrer M, Torres A. Endotracheal tube biofilm translocation in the lateral Trendelenburg position. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:59. [PMID: 25887536 PMCID: PMC4355496 DOI: 10.1186/s13054-015-0785-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 02/03/2015] [Indexed: 12/11/2022]
Abstract
Introduction Laboratory studies demonstrated that the lateral Trendelenburg position (LTP) is superior to the semirecumbent position (SRP) in the prevention of ventilator-associated pulmonary infections. We assessed whether the LTP could also prevent pulmonary colonization and infections caused by an endotracheal tube (ETT) biofilm. Methods Eighteen pigs were intubated with ETTs colonized by Pseudomonas aeruginosa biofilm. Pigs were positioned in LTP and randomized to be on mechanical ventilatin (MV) up to 24 hour, 48 hour, 48 hour with acute lung injury (ALI) by oleic acid and 72 hour. Bacteriologic and microscopy studies confirmed presence of biofilm within the ETT. Upon autopsy, samples from the proximal and distal airways were excised for P.aeruginosa quantification. Ventilator-associated tracheobronchitis (VAT) was confirmed by bronchial tissue culture ≥3 log colony forming units per gram (cfu/g). In pulmonary lobes with gross findings of pneumonia, ventilator-associated pneumonia (VAP) was confirmed by lung tissue culture ≥3 log cfu/g. Results P.aeruginosa colonized the internal lumen of 16 out of 18 ETTs (88.89%), and a mature biofilm was consistently present. P.aeruginosa colonization did not differ among groups, and was found in 23.6% of samples from the proximal airways, and in 7.1% from the distal bronchi (P = 0.001). Animals of the 24 hour group never developed respiratory infections, whereas 20%, 60% and 25% of the animals in group 48 hour, 48 hour-ALI and 72 hour developed P.aeruginosa VAT, respectively (P = 0.327). Nevertheless, VAP never developed. Conclusions Our findings imply that during the course of invasive MV up to 72 hour, an ETT P.aeruginosa biofilm hastily colonizes the respiratory tract. Yet, the LTP compartmentalizes colonization and infection within the proximal airways and VAP never develops.
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Affiliation(s)
- Gianluigi Li Bassi
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain.
| | - Laia Fernandez-Barat
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain.
| | - Lina Saucedo
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain.
| | | | - Joan Daniel Marti
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain.
| | - Otavio Tavares Ranzani
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain. .,Hospital das Clínicas, Faculdade de Medicina da Universidade de São Paulo, Pulmonary Intensive Care Unit, São Paulo, Brazil.
| | - Eli Aguilera Xiol
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain.
| | - Montserrat Rigol
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain.
| | - Ignasi Roca
- Department of Clinical Microbiology, School of Medicine, and Barcelona Centre for International Health Research, (CRESIB) Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
| | - Laura Muñoz
- Department of Clinical Microbiology, School of Medicine, and Barcelona Centre for International Health Research, (CRESIB) Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
| | - Nestor Luque
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain.
| | - Mariano Esperatti
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain.
| | | | - Jose Ramirez
- Pathology Department, Hospital Clinic, Barcelona, Spain.
| | - Jordi Vila
- Department of Clinical Microbiology, School of Medicine, and Barcelona Centre for International Health Research, (CRESIB) Hospital Clínic, Universitat de Barcelona, Barcelona, Spain. .,University of Barcelona, Barcelona, Spain.
| | - Miguel Ferrer
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain.
| | - Antoni Torres
- Pulmonary and Critical Care Unit, Hospital Clínic, Calle Villarroel 170, Esc 6/8 Planta 2, 08036, Barcelona, Spain. .,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain. .,Centro de Investigación Biomedica En Red- Enfermedades Respiratorias (CIBERES), Mallorca, Spain. .,University of Barcelona, Barcelona, Spain.
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Managing hypercapnia in patients with severe ARDS and low respiratory system compliance: the role of esophageal pressure monitoring--a case cohort study. BIOMED RESEARCH INTERNATIONAL 2015; 2015:385042. [PMID: 25695069 PMCID: PMC4324110 DOI: 10.1155/2015/385042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 10/01/2014] [Accepted: 10/13/2014] [Indexed: 11/29/2022]
Abstract
Purpose. Patients with severe acute respiratory distress syndrome (ARDS) and hypercapnia present a formidable treatment challenge. We examined the use of esophageal balloon for assessment of transpulmonary pressures to guide mechanical ventilation for successful management of severe hypercapnia. Materials and Methods. Patients with severe ARDS and hypercapnia were studied. Esophageal balloon was inserted and mechanical ventilation was guided by assessment of transpulmonary pressures. Positive end expiratory pressure (PEEP) and inspiratory driving pressures were adjusted with the aim of achieving tidal volume of 6 to 8 mL/kg based on ideal body weight (IBW), while not exceeding end inspiratory transpulmonary (EITP) pressure of 25 cm H2O. Results. Six patients with severe ARDS and hypercapnia were studied. Mean PaCO2 on enrollment was 108.33 ± 25.65 mmHg. One hour after adjustment of PEEP and inspiratory driving pressure guided by transpulmonary pressure, PaCO2 decreased to 64.5 ± 16.89 mmHg (P < 0.01). Tidal volume was 3.96 ± 0.92 mL/kg IBW before and increased to 7.07 ± 1.21 mL/kg IBW after intervention (P < 0.01). EITP pressure before intervention was low with a mean of 13.68 ± 8.69 cm H2O and remained low at 16.76 ± 4.76 cm H2O (P = 0.18) after intervention. Adjustment of PEEP and inspiratory driving pressures did not worsen oxygenation and did not affect cardiac output significantly. Conclusion. The use of esophageal balloon as a guide to mechanical ventilation was able to treat severe hypercapnia in ARDS patients.
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LUNDIN S, GRIVANS C, STENQVIST O. Transpulmonary pressure and lung elastance can be estimated by a PEEP-step manoeuvre. Acta Anaesthesiol Scand 2015; 59:185-96. [PMID: 25443094 DOI: 10.1111/aas.12442] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 10/15/2014] [Indexed: 01/17/2023]
Abstract
BACKGROUND Transpulmonary pressure is a key factor for protective ventilation. This requires measurements of oesophageal pressure that is rarely used clinically. A simple method may be found, if it could be shown that tidal and positive end-expiratory pressure (PEEP) inflation of the lungs with the same volume increases transpulmonary pressure equally. The aim of the present study was to compare tidal and PEEP inflation of the respiratory system. METHODS A total of 12 patients with acute respiratory failure were subjected to PEEP trials of 0-4-8-12-16 cmH2O. Changes in end-expiratory lung volume (ΔEELV) following a PEEP step were determined from cumulative differences in inspiratory-expiratory tidal volumes. Oesophageal pressure was measured with a balloon catheter. RESULTS Following a PEEP increase from 0 to 16 cmH2O end-expiratory oesophageal pressure did not increase (0.5 ± 4.0 cmH2O). Average increase in EELV following a PEEP step of 4 cmH2O was 230 ± 132 ml. The increase in EELV was related to the change in PEEP divided by lung elastance (El) derived from oesophageal pressure as ΔPEEP/El. There was a good correlation between transpulmonary pressure by oesophageal pressure and transpulmonary pressure based on El determined as ΔPEEP/ΔEELV, r(2) = 0.80, y = 0.96x, mean bias -0.4 ± 3.0 cmH2 O with limits of agreement from 5.4 to -6.2 cmH2O (2 standard deviations). CONCLUSION PEEP inflation of the respiratory system is extremely slow, and allows the chest wall complex, especially the abdomen, to yield and adapt to intrusion of the diaphragm. As a consequence a change in transpulmonary pressure is equal to the change in PEEP and transpulmonary pressure can be determined without oesophageal pressure measurements.
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Affiliation(s)
- S. LUNDIN
- Department of Anesthesiology and Intensive Care; Sahlgrenska University Hospital; Gothenburg Sweden
| | - C. GRIVANS
- Department of Anesthesiology and Intensive Care; Sahlgrenska University Hospital; Gothenburg Sweden
| | - O. STENQVIST
- Department of Anesthesiology and Intensive Care; Sahlgrenska University Hospital; Gothenburg Sweden
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Das A, Cole O, Chikhani M, Wang W, Ali T, Haque M, Bates DG, Hardman JG. Evaluation of lung recruitment maneuvers in acute respiratory distress syndrome using computer simulation. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:8. [PMID: 25578295 PMCID: PMC4329196 DOI: 10.1186/s13054-014-0723-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 12/16/2014] [Indexed: 02/03/2023]
Abstract
Introduction Direct comparison of the relative efficacy of different recruitment maneuvers (RMs) for patients with acute respiratory distress syndrome (ARDS) via clinical trials is difficult, due to the heterogeneity of patient populations and disease states, as well as a variety of practical issues. There is also significant uncertainty regarding the minimum values of positive end-expiratory pressure (PEEP) required to ensure maintenance of effective lung recruitment using RMs. We used patient-specific computational simulation to analyze how three different RMs act to improve physiological responses, and investigate how different levels of PEEP contribute to maintaining effective lung recruitment. Methods We conducted experiments on five ‘virtual’ ARDS patients using a computational simulator that reproduces static and dynamic features of a multivariable clinical dataset on the responses of individual ARDS patients to a range of ventilator inputs. Three recruitment maneuvers (sustained inflation (SI), maximal recruitment strategy (MRS) followed by a titrated PEEP, and prolonged recruitment maneuver (PRM)) were implemented and evaluated for a range of different pressure settings. Results All maneuvers demonstrated improvements in gas exchange, but the extent and duration of improvement varied significantly, as did the observed mechanism of operation. Maintaining adequate post-RM levels of PEEP was seen to be crucial in avoiding cliff-edge type re-collapse of alveolar units for all maneuvers. For all five patients, the MRS exhibited the most prolonged improvement in oxygenation, and we found that a PEEP setting of 35 cm H2O with a fixed driving pressure of 15 cm H2O (above PEEP) was sufficient to achieve 95% recruitment. Subsequently, we found that PEEP titrated to a value of 16 cm H2O was able to maintain 95% recruitment in all five patients. Conclusions There appears to be significant scope for reducing the peak levels of PEEP originally specified in the MRS and hence to avoid exposing the lung to unnecessarily high pressures. More generally, our study highlights the huge potential of computer simulation to assist in evaluating the efficacy of different recruitment maneuvers, in understanding their modes of operation, in optimizing RMs for individual patients, and in supporting clinicians in the rational design of improved treatment strategies. Electronic supplementary material The online version of this article (doi:10.1186/s13054-014-0723-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anup Das
- School of Engineering, University of Warwick, Library Road, Coventry, CV4 7AL, UK.
| | - Oana Cole
- Anaesthesia & Critical Care Research Group, University of Nottingham, Derby Road, Nottingham, NG7 2UH, UK.
| | - Marc Chikhani
- Anaesthesia & Critical Care Research Group, University of Nottingham, Derby Road, Nottingham, NG7 2UH, UK.
| | - Wenfei Wang
- School of Engineering, University of Warwick, Library Road, Coventry, CV4 7AL, UK.
| | - Tayyba Ali
- Anaesthesia & Critical Care Research Group, University of Nottingham, Derby Road, Nottingham, NG7 2UH, UK.
| | - Mainul Haque
- Anaesthesia & Critical Care Research Group, University of Nottingham, Derby Road, Nottingham, NG7 2UH, UK.
| | - Declan G Bates
- School of Engineering, University of Warwick, Library Road, Coventry, CV4 7AL, UK.
| | - Jonathan G Hardman
- Anaesthesia & Critical Care Research Group, University of Nottingham, Derby Road, Nottingham, NG7 2UH, UK.
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Monitoring Lung Volumes During Mechanical Ventilation. PEDIATRIC AND NEONATAL MECHANICAL VENTILATION 2015. [PMCID: PMC7193716 DOI: 10.1007/978-3-642-01219-8_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Respiratory inductive plethysmography (RIP) is a non-invasive method of measuring change in lung volume which is well-established as a monitor of tidal ventilation and thus respiratory patterns in sleep medicine. As RIP is leak independent, can measure end-expiratory lung volume as well as tidal volume and is applicable to both the ventilated and spontaneously breathing patient, there has been a recent interest in its use as a bedside tool in the intensive care unit.
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Compressive forces and computed tomography-derived positive end-expiratory pressure in acute respiratory distress syndrome. Anesthesiology 2014; 121:572-81. [PMID: 25050573 DOI: 10.1097/aln.0000000000000373] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
BACKGROUND It has been suggested that higher positive end-expiratory pressure (PEEP) should be used only in patients with higher lung recruitability. In this study, the authors investigated the relationship between the recruitability and the PEEP necessary to counteract the compressive forces leading to lung collapse. METHODS Fifty-one patients with acute respiratory distress syndrome (7 mild, 33 moderate, and 11 severe) were enrolled. Patients underwent whole-lung computed tomography (CT) scan at 5 and 45 cm H2O. Recruitability was measured as the amount of nonaerated tissue regaining inflation from 5 to 45 cm H2O. The compressive forces (superimposed pressure) were computed as the density times the sternum-vertebral height of the lung. CT-derived PEEP was computed as the sum of the transpulmonary pressure needed to overcome the maximal superimposed pressure and the pleural pressure needed to lift up the chest wall. RESULTS Maximal superimposed pressure ranged from 6 to 18 cm H2O, whereas CT-derived PEEP ranged from 7 to 28 cm H2O. Median recruitability was 15% of lung parenchyma (interquartile range, 7 to 21%). Maximal superimposed pressure was weakly related with lung recruitability (r = 0.11, P = 0.02), whereas CT-derived PEEP was unrelated with lung recruitability (r = 0.0003, P = 0.91). The maximal superimposed pressure was 12 ± 3, 12 ± 2, and 13 ± 1 cm H2O in mild, moderate, and severe acute respiratory distress syndrome, respectively, (P = 0.0533) with a corresponding CT-derived PEEP of 16 ± 5, 16 ± 5, and 18 ± 5 cm H2O (P = 0.48). CONCLUSIONS Lung recruitability and CT scan-derived PEEP are unrelated. To overcome the compressive forces and to lift up the thoracic cage, a similar PEEP level is required in higher and lower recruiters (16.8 ± 4 vs. 16.6 ± 5.6, P = 1).
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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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132
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Sutherasan Y, D'Antini D, Pelosi P. Advances in ventilator-associated lung injury: prevention is the target. Expert Rev Respir Med 2014; 8:233-48. [PMID: 24601663 DOI: 10.1586/17476348.2014.890519] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Mechanical ventilation (MV) is the main supportive treatment in respiratory failure due to different etiologies. However, MV might aggravate ventilator-associated lung injury (VALI). Four main mechanisms leading to VALI are: 1) increased stress and strain, induced by high tidal volume (VT); 2) increased shear stress, i.e. opening and closing, of previously atelectatic alveolar units; 3) distribution of perfusion and 4) biotrauma. In severe acute respiratory distress syndrome patients, low VT, higher levels of positive end expiratory pressure, long duration prone position and neuromuscular blockade within the first 48 hours are associated to a better outcome. VALI can also occur by using high VT in previously non injured lungs. We believe that prevention is the target to minimize injurious effects of MV. This review aims to describe pathophysiology of VALI, the possible prevention and treatment as well as monitoring MV to minimize VALI.
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Affiliation(s)
- Yuda Sutherasan
- Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, IRCCS San Martino - IST, Genoa, Italy
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133
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Redmond D, Chiew YS, van Drunen E, Shaw GM, Chase JG. A minimal algorithm for a minimal recruitment model–model estimation of alveoli opening pressure of an acute respiratory distress syndrome (ARDS) lung. Biomed Signal Process Control 2014. [DOI: 10.1016/j.bspc.2014.05.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
PURPOSE OF REVIEW Supporting patients with acute respiratory distress syndrome (ARDS) using a low tidal volume strategy is a standard practice in the ICU. Recruitment maneuvers can be used to augment other methods, like positive end-expiratory pressure and positioning, to improve aerated lung volume. Clinical practice varies widely, and optimal method and patient selection for recruitment maneuvers have not been determined. RECENT FINDINGS Recent developments include experimental and clinical evidence that a stepwise extended recruitment maneuver may match the improvement in aerated lung volume seen with sustained inflation traditionally used, with less adverse effects. Positioning and other chest wall modifications may be useful adjuncts to recruitment maneuvers. In addition, evidence from clinical studies in the operating room suggests that recruitment maneuvers, as a component of an open lung strategy, may be helpful for mechanically ventilated patients with normal lungs. SUMMARY As a component of ventilation strategy for patients with ARDS, the use of recruitment maneuvers, especially a stepwise maneuver, in addition to adequate positive end-expiratory pressure and appropriate positioning, is suggested by currently available data. Until their effect on clinical outcomes is further defined, the use of recruitment maneuvers in ARDS and other settings will continue to be guided by individual clinician experience and patient factors.
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135
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Abstract
Multiple animal and human studies have shown that prone positioning improves oxygenation and reduces ventilator-induced lung injury (VILI) in the setting of acute lung injury or acute respiratory distress syndrome (ARDS). In this article, the physiologic changes explaining the improvement in oxygenation are reviewed, how prone positioning reduces VILI is described, randomized controlled trials of prone ventilation in patients with ARDS are evaluated, the complications associated with prone ventilation are summarized, suggestions are made as to how these might be reduced or avoided, and when prone ventilation should start and stop and for what duration it should be used are discussed.
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Affiliation(s)
- Alexander B Benson
- University of Colorado, 12605 E, 16th avenue, Aurora, CO 80045, USA; Department of Medicine, Denver Health, 777 Bannock, MC 4000, Denver, CO 80204-4507, USA
| | - Richard K Albert
- University of Colorado, 12605 E, 16th avenue, Aurora, CO 80045, USA; Department of Medicine, Denver Health, 777 Bannock, MC 4000, Denver, CO 80204-4507, USA.
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136
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Beda A, Güldner A, Carvalho AR, Zin WA, Carvalho NC, Huhle R, Giannella-Neto A, Koch T, de Abreu MG. Liquid- and air-filled catheters without balloon as an alternative to the air-filled balloon catheter for measurement of esophageal pressure. PLoS One 2014; 9:e103057. [PMID: 25247308 PMCID: PMC4172426 DOI: 10.1371/journal.pone.0103057] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/26/2014] [Indexed: 11/25/2022] Open
Abstract
Background Measuring esophageal pressure (Pes) using an air-filled balloon catheter (BC) is the common approach to estimate pleural pressure and related parameters. However, Pes is not routinely measured in mechanically ventilated patients, partly due to technical and practical limitations and difficulties. This study aimed at comparing the conventional BC with two alternative methods for Pes measurement, liquid-filled and air-filled catheters without balloon (LFC and AFC), during mechanical ventilation with and without spontaneous breathing activity. Seven female juvenile pigs (32–42 kg) were anesthetized, orotracheally intubated, and a bundle of an AFC, LFC, and BC was inserted in the esophagus. Controlled and assisted mechanical ventilation were applied with positive end-expiratory pressures of 5 and 15 cmH2O, and driving pressures of 10 and 20 cmH2O, in supine and lateral decubitus. Main Results Cardiogenic noise in BC tracings was much larger (up to 25% of total power of Pes signal) than in AFC and LFC (<3%). Lung and chest wall elastance, pressure-time product, inspiratory work of breathing, inspiratory change and end-expiratory value of transpulmonary pressure were estimated. The three catheters allowed detecting similar changes in these parameters between different ventilation settings. However, a non-negligible and significant bias between estimates from BC and those from AFC and LFC was observed in several instances. Conclusions In anesthetized and mechanically ventilated pigs, the three catheters are equivalent when the aim is to detect changes in Pes and related parameters between different conditions, but possibly not when the absolute value of the estimated parameters is of paramount importance. Due to a better signal-to-noise ratio, and considering its practical advantages in terms of easier calibration and simpler acquisition setup, LFC may prove interesting for clinical use.
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Affiliation(s)
- Alessandro Beda
- Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
- Department of Electronic Engineering and Postgraduate Program of Electrical Engineering, Federal University of Minas Gerais, Pampulha, Belo Horizonte, Brazil
- * E-mail:
| | - Andreas Güldner
- Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
| | - Alysson R. Carvalho
- Laboratory of Respiration Physiology, Carlos Chagas Filho Biophysics Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- Biomedical Engineering Program, Alberto Luis Coimbra Program of Post-Graduation and Research in Engineering, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Walter Araujo Zin
- Laboratory of Respiration Physiology, Carlos Chagas Filho Biophysics Institute, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nadja C. Carvalho
- Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
- Department of Electronic Engineering and Postgraduate Program of Electrical Engineering, Federal University of Minas Gerais, Pampulha, Belo Horizonte, Brazil
| | - Robert Huhle
- Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
| | - Antonio Giannella-Neto
- Biomedical Engineering Program, Alberto Luis Coimbra Program of Post-Graduation and Research in Engineering, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Thea Koch
- Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
| | - Marcelo Gama de Abreu
- Pulmonary Engineering Group, Clinic of Anaesthesiology and Intensive Care Therapy, University Hospital Dresden, Technische Universität Dresden, Dresden, Germany
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137
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Guo R, Fan E. Beyond low tidal volumes: ventilating the patient with acute respiratory distress syndrome. Clin Chest Med 2014; 35:729-41. [PMID: 25453421 DOI: 10.1016/j.ccm.2014.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cornerstone of lung protective ventilation in patients with acute respiratory distress syndrome (ARDS) is a pressure- and volume-limited strategy. Other interventions have also been investigated. Although no method for positive end-expiratory pressure (PEEP) titration has proven most advantageous, experimental and clinical data support the use of higher PEEP in patients with moderate/severe ARDS. There is no benefit to the early use of high-frequency oscillatory ventilation (HFOV) in patients with moderate/severe ARDS, although it may be considered as rescue therapy. Further investigations of novel methods of bedside monitoring of mechanical ventilation may help identify the optimal ventilatory strategy.
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Affiliation(s)
- Ray Guo
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Eddy Fan
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada.
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138
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Moraes L, Santos CL, Santos RS, Cruz FF, Saddy F, Morales MM, Capelozzi VL, Silva PL, de Abreu MG, Garcia CSNB, Pelosi P, Rocco PRM. Effects of sigh during pressure control and pressure support ventilation in pulmonary and extrapulmonary mild acute lung injury. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2014; 18:474. [PMID: 25113136 PMCID: PMC4155110 DOI: 10.1186/s13054-014-0474-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/23/2014] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Sigh improves oxygenation and lung mechanics during pressure control ventilation (PCV) and pressure support ventilation (PSV) in patients with acute respiratory distress syndrome. However, so far, no study has evaluated the biological impact of sigh during PCV or PSV on the lung and distal organs in experimental pulmonary (p) and extrapulmonary (exp) mild acute lung injury (ALI). METHODS In 48 Wistar rats, ALI was induced by Escherichia coli lipopolysaccharide either intratracheally (ALIp) or intraperitoneally (ALIexp). After 24 hours, animals were anesthetized and mechanically ventilated with PCV or PSV with a tidal volume of 6 mL/kg, FiO2 = 0.4, and PEEP = 5 cmH2O for 1 hour. Both ventilator strategies were then randomly assigned to receive periodic sighs (10 sighs/hour, Sigh) or not (non-Sigh, NS). Ventilatory and mechanical parameters, arterial blood gases, lung histology, interleukin (IL)-1β, IL-6, caspase-3, and type III procollagen (PCIII) mRNA expression in lung tissue, and number of apoptotic cells in lung, liver, and kidney specimens were analyzed. RESULTS In both ALI etiologies: (1) PCV-Sigh and PSV-Sigh reduced transpulmonary pressure, and (2) PSV-Sigh reduced the respiratory drive compared to PSV-NS. In ALIp: (1) PCV-Sigh and PSV-Sigh decreased alveolar collapse as well as IL-1β, IL-6, caspase-3, and PCIII expressions in lung tissue, (2) PCV-Sigh increased alveolar-capillary membrane and endothelial cell damage, and (3) abnormal myofibril with Z-disk edema was greater in PCV-NS than PSV-NS. In ALIexp: (1) PSV-Sigh reduced alveolar collapse, but led to damage to alveolar-capillary membrane, as well as type II epithelial and endothelial cells, (2) PCV-Sigh and PSV-Sigh increased IL-1β, IL-6, caspase-3, and PCIII expressions, and (3) PCV-Sigh increased the number of apoptotic cells in the lung compared to PCV-NS. CONCLUSIONS In these models of mild ALIp and ALIexp, sigh reduced alveolar collapse and transpulmonary pressures during both PCV and PSV; however, improved lung protection only during PSV in ALIp.
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139
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The assessment of transpulmonary pressure in mechanically ventilated ARDS patients. Intensive Care Med 2014; 40:1670-8. [PMID: 25112501 DOI: 10.1007/s00134-014-3415-4] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/19/2014] [Indexed: 10/24/2022]
Abstract
PURPOSE The optimal method for estimating transpulmonary pressure (i.e. the fraction of the airway pressure transmitted to the lung) has not yet been established. METHODS In this study on 44 patients with acute respiratory distress syndrome (ARDS), we computed the end-inspiratory transpulmonary pressure as the change in airway and esophageal pressure from end-inspiration to atmospheric pressure (i.e. release derived) and as the product of the end-inspiratory airway pressure and the ratio of lung to respiratory system elastance (i.e. elastance derived). The end-expiratory transpulmonary pressure was estimated as the product of positive end-expiratory pressure (PEEP) minus the direct measurement of esophageal pressure and by the release method. RESULTS The mean elastance- and release-derived transpulmonary pressure were 14.4 ± 3.7 and 14.4 ± 3.8 cmH₂O at 5 cmH₂O of PEEP and 21.8 ± 5.1 and 21.8 ± 4.9 cmH₂O at 15 cmH₂O of PEEP, respectively (P = 0.32, P = 0.98, respectively), indicating that these parameters were significantly related (r(2) = 0.98, P < 0.001 at 5 cmH₂O of PEEP; r(2) = 0.93, P < 0.001 at 15 cmH₂O of PEEP). The percentage error was 5.6 and 12.0 %, respectively. The mean directly measured and release-derived transpulmonary pressure were -8.0 ± 3.8 and 3.9 ± 0.9 cmH₂O at 5 cmH₂O of PEEP and -1.2 ± 3.2 and 10.6 ± 2.2 cmH₂O at 15 cmH₂O of PEEP, respectively, indicating that these parameters were not related (r(2) = 0.07, P = 0.08 at 5 cmH₂O of PEEP; r (2) = 0.10, P = 0.53 at 15 cmH₂O of PEEP). CONCLUSIONS Based on our observations, elastance-derived transpulmonary pressure can be considered to be an adequate surrogate of the release-derived transpulmonary pressure, while the release-derived and directly measured end-expiratory transpulmonary pressure are not related.
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140
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Wu Y, Kharge AB, Perlman CE. Lung ventilation injures areas with discrete alveolar flooding, in a surface tension-dependent fashion. J Appl Physiol (1985) 2014; 117:788-96. [PMID: 25080924 DOI: 10.1152/japplphysiol.00569.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
With proteinaceous-liquid flooding of discrete alveoli, a model of the edema pattern in the acute respiratory distress syndrome, lung inflation over expands aerated alveoli adjacent to flooded alveoli. Theoretical considerations suggest that the overexpansion may be proportional to surface tension, T. Yet recent evidence indicates proteinaceous edema liquid may not elevate T. Thus whether the overexpansion is injurious is not known. Here, working in the isolated, perfused rat lung, we quantify fluorescence movement from the vasculature to the alveolar liquid phase as a measure of overdistension injury to the alveolar-capillary barrier. We label the perfusate with fluorescence; micropuncture a surface alveolus and instill a controlled volume of nonfluorescent liquid to obtain a micropunctured-but-aerated region (control group) or a region with discrete alveolar flooding; image the region at a constant transpulmonary pressure of 5 cmH2O; apply five ventilation cycles with a positive end-expiratory pressure of 0-20 cmH2O and tidal volume of 6 or 12 ml/kg; return the lung to a constant transpulmonary pressure of 5 cmH2O; and image for an additional 10 min. In aerated areas, ventilation is not injurious. With discrete alveolar flooding, all ventilation protocols cause sustained injury. Greater positive end-expiratory pressure or tidal volume increases injury. Furthermore, we determine T and find injury increases with T. Inclusion of either plasma proteins or Survanta in the flooding liquid does not alter T or injury. Inclusion of 2.7-10% albumin and 1% Survanta together, however, lowers T and injury. Contrary to expectation, albumin inclusion in our model facilitates exogenous surfactant activity.
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Affiliation(s)
- You Wu
- Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
| | - Angana Banerjee Kharge
- Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
| | - Carrie E Perlman
- Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
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141
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Kharge AB, Wu Y, Perlman CE. Surface tension in situ in flooded alveolus unaltered by albumin. J Appl Physiol (1985) 2014; 117:440-51. [PMID: 24970853 DOI: 10.1152/japplphysiol.00084.2014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In the acute respiratory distress syndrome, plasma proteins in alveolar edema liquid are thought to inactivate lung surfactant and raise surface tension, T. However, plasma protein-surfactant interaction has been assessed only in vitro, during unphysiologically large surface area compression (%ΔA). Here, we investigate whether plasma proteins raise T in situ in the isolated rat lung under physiologic conditions. We flood alveoli with liquid that omits/includes plasma proteins. We ventilate the lung between transpulmonary pressures of 5 and 15 cmH2O to apply a near-maximal physiologic %ΔA, comparable to that of severe mechanical ventilation, or between 1 and 30 cmH2O, to apply a supraphysiologic %ΔA. We pause ventilation for 20 min and determine T at the meniscus that is present at the flooded alveolar mouth. We determine alveolar air pressure at the trachea, alveolar liquid phase pressure by servo-nulling pressure measurement, and meniscus radius by confocal microscopy, and we calculate T according to the Laplace relation. Over 60 ventilation cycles, application of maximal physiologic %ΔA to alveoli flooded with 4.6% albumin solution does not alter T; supraphysiologic %ΔA raise T, transiently, by 51 ± 4%. In separate experiments, we find that addition of exogenous surfactant to the alveolar liquid can, with two cycles of maximal physiologic %ΔA, reduce T by 29 ± 11% despite the presence of albumin. We interpret that supraphysiologic %ΔA likely collapses the interfacial surfactant monolayer, allowing albumin to raise T. With maximal physiologic %ΔA, the monolayer likely remains intact such that albumin, blocked from the interface, cannot interfere with native or exogenous surfactant activity.
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Affiliation(s)
- Angana Banerjee Kharge
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
| | - You Wu
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
| | - Carrie E Perlman
- Department of Chemistry, Chemical Biology & Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey
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142
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Pelosi P, Quintel M, Malbrain MLNG. Effect of intra-abdominal pressure on respiratory mechanics. Acta Clin Belg 2014; 62 Suppl 1:78-88. [PMID: 24881704 DOI: 10.1179/acb.2007.62.s1.011] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
INTRODUCTION There has been an exponentially increasing interest in intra-abdominal hypertension (IAH). The intra-abdominal pressure (IAP) markedly affects the function of the respiratory system. METHODS This review will focus on the available literature from the past few years. A Medline and Pubmed search was performed in order to find an answer to the question "What is the impact of increased IAP on respiratory function in the critically ill?". RESULTS In particular, increased IAP increases chest wall elastance (or decreases compliance) and promotes cranial shift of the diaphragm, with consequent reduction in lung volume and atelectasis formation. Compression of the lung parenchyma also triggers pulmonary infection. During general anaesthesia, in normal subjects, IAP does not affect the chest wall mechanics, but plays a relevant role in the caudal-cranial displacement of the abdominal content, the diaphragm and consequent changes in lung mechanics and function. In obese patients, the increased IAP is the major determinant of the reduction in lung volume, atelectasis formation and alterations in chest wall mechanics. In ARDS patients the measurement of IAP and chest wall mechanics is important for a better interpretation of respiratory mechanics, hemodynamics and appropriate setting of the ventilator. Furthermore, increased IAP promotes lung oedema, ventilator induced lung injury and reduced lymphatic flow in normal and diseased lungs. CONCLUSION Increased IAP markedly affects respiratory function in such a way that it has an impact on daily clinical practise.
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143
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Ball L, Sutherasan Y, Pelosi P. Monitoring respiration: what the clinician needs to know. Best Pract Res Clin Anaesthesiol 2014; 27:209-23. [PMID: 24012233 DOI: 10.1016/j.bpa.2013.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/07/2013] [Accepted: 06/12/2013] [Indexed: 10/26/2022]
Abstract
A recent large prospective cohort study showed an unexpectedly high in-hospital mortality after major non-cardiac surgery in Europe, as well as a high incidence of postoperative pulmonary complications. The direct effect of postoperative respiratory complications on mortality is still under investigation, for intensive care unit (ICU) and in the perioperative period. Although respiratory monitoring has not been actually proven to affect in-hospital mortality, it plays an important role in patient care, leading to appropriate setting of ventilatory support as well as risk stratification. The aim of this article is to provide an overview of various respiratory monitoring techniques including the role of conventional and most recent methods in the perioperative period and in critically ill patients. The most recent techniques proposed for bedside respiratory monitoring, including lung imaging, are presented and discussed, comparing them to those actually considered as gold standards.
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Affiliation(s)
- Lorenzo Ball
- IRCCS AOU San Martino-IST, Department of Surgical Sciences and Integrated Diagnostics, University of Genoa, Genoa, Italy.
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Abstract
Mechanical ventilation of patients with acute respiratory distress syndrome (ARDS) is a necessary life support measure which may lead to ventilator-induced lung injury, a complication that can be reduced or ameliorated by using appropriate tidal volumes and positive end-expiratory pressures. However, the optimal mechanical ventilation parameters are almost certainly different for each patient, and will vary with time as the injury status of the lung changes. In order to optimize mechanical ventilation in an individual ARDS patient, therefore, it is necessary to track the manner in which injury status is reflected in the mechanical properties of the lungs. Accordingly, we developed an algorithm for assessing the time-dependent manner in which different lung regions open (recruit) and close (derecruit) as a function of the pressure waveform that is applied to the airways during mechanical ventilation. We used this algorithm to test the notion that variable ventilation provides the dynamic perturbations in lung volume necessary to accurately identify recruitment/derecruitment dynamics in the injured lung. We performed this test on synthetic pressure and flow data generated with established numerical models of lung function corresponding to both healthy mice and mice with lung injury. The data were generated by subjecting the models to a variety of mechanical ventilation regimens including variable ventilation. Our results support the hypothesis that variable ventilation can be used as a diagnostic tool to identify the injury status of the lung in ARDS.
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145
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Bedside selection of positive end-expiratory pressure in mild, moderate, and severe acute respiratory distress syndrome. Crit Care Med 2014; 42:252-64. [PMID: 24196193 DOI: 10.1097/ccm.0b013e3182a6384f] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Positive end-expiratory pressure exerts its effects keeping open at end-expiration previously collapsed areas of the lung; consequently, higher positive end-expiratory pressure should be limited to patients with high recruitability. We aimed to determine which bedside method would provide positive end-expiratory pressure better related to lung recruitability. DESIGN Prospective study performed between 2008 and 2011. SETTING Two university hospitals (Italy and Germany). PATIENTS Fifty-one patients with acute respiratory distress syndrome. INTERVENTIONS Whole lung CT scans were taken in static conditions at 5 and 45 cm H2O during an end-expiratory/end-inspiratory pause to measure lung recruitability. To select individual positive end-expiratory pressure, we applied bedside methods based on lung mechanics (ExPress, stress index), esophageal pressure, and oxygenation (higher positive end-expiratory pressure table of lung open ventilation study). MEASUREMENTS AND MAIN RESULTS Patients were classified in mild, moderate and severe acute respiratory distress syndrome. Positive end-expiratory pressure levels selected by the ExPress, stress index, and absolute esophageal pressures methods were unrelated with lung recruitability, whereas positive end-expiratory pressure levels selected by the lung open ventilation method showed a weak relationship with lung recruitability (r = 0.29; p < 0.0001). When patients were classified according to the acute respiratory distress syndrome Berlin definition, the lung open ventilation method was the only one which gave lower positive end-expiratory pressure levels in mild and moderate acute respiratory distress syndrome compared with severe acute respiratory distress syndrome (8 ± 2 and 11 ± 3 cm H2O vs 15 ± 3 cm H2O; p < 0.05), whereas ExPress, stress index, and esophageal pressure methods gave similar positive end-expiratory pressure values in mild, moderate, and severe acute respiratory distress syndrome. The positive end-expiratory pressure selected by the different methods were unrelated to each other with the exception of the two methods based on lung mechanics (ExPress and stress index). CONCLUSIONS Bedside positive end-expiratory pressure selection methods based on lung mechanics or absolute esophageal pressures provide positive end-expiratory pressure levels unrelated to lung recruitability and similar in mild, moderate, and severe acute respiratory distress syndrome, whereas the oxygenation-based method provided positive end-expiratory pressure levels related with lung recruitability progressively increasing from mild to moderate and severe acute respiratory distress syndrome.
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146
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van Drunen EJ, Chiew YS, Pretty C, Shaw GM, Lambermont B, Janssen N, Chase JG, Desaive T. Visualisation of time-varying respiratory system elastance in experimental ARDS animal models. BMC Pulm Med 2014; 14:33. [PMID: 24581274 PMCID: PMC4016000 DOI: 10.1186/1471-2466-14-33] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Accepted: 02/19/2014] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Patients with acute respiratory distress syndrome (ARDS) risk lung collapse, severely altering the breath-to-breath respiratory mechanics. Model-based estimation of respiratory mechanics characterising patient-specific condition and response to treatment may be used to guide mechanical ventilation (MV). This study presents a model-based approach to monitor time-varying patient-ventilator interaction to guide positive end expiratory pressure (PEEP) selection. METHODS The single compartment lung model was extended to monitor dynamic time-varying respiratory system elastance, Edrs, within each breathing cycle. Two separate animal models were considered, each consisting of three fully sedated pure pietrain piglets (oleic acid ARDS and lavage ARDS). A staircase recruitment manoeuvre was performed on all six subjects after ARDS was induced. The Edrs was mapped across each breathing cycle for each subject. RESULTS Six time-varying, breath-specific Edrs maps were generated, one for each subject. Each Edrs map shows the subject-specific response to mechanical ventilation (MV), indicating the need for a model-based approach to guide MV. This method of visualisation provides high resolution insight into the time-varying respiratory mechanics to aid clinical decision making. Using the Edrs maps, minimal time-varying elastance was identified, which can be used to select optimal PEEP. CONCLUSIONS Real-time continuous monitoring of in-breath mechanics provides further insight into lung physiology. Therefore, there is potential for this new monitoring method to aid clinicians in guiding MV treatment. These are the first such maps generated and they thus show unique results in high resolution. The model is limited to a constant respiratory resistance throughout inspiration which may not be valid in some cases. However, trends match clinical expectation and the results highlight both the subject-specificity of the model, as well as significant inter-subject variability.
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147
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Guerin C, Richard JC. Current ventilatory management of patients with acute lung injury/acute respiratory distress syndrome. Expert Rev Respir Med 2014; 2:119-33. [DOI: 10.1586/17476348.2.1.119] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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148
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Abstract
This article describes the gas exchange abnormalities occurring in the acute respiratory distress syndrome seen in adults and children and in the respiratory distress syndrome that occurs in neonates. Evidence is presented indicating that the major gas exchange abnormality accounting for the hypoxemia in both conditions is shunt, and that approximately 50% of patients also have lungs regions in which low ventilation-to-perfusion ratios contribute to the venous admixture. The various mechanisms by which hypercarbia may develop and by which positive end-expiratory pressure improves gas exchange are reviewed, as are the effects of vascular tone and airway narrowing. The mechanisms by which surfactant abnormalities occur in the two conditions are described, as are the histological findings that have been associated with shunt and low ventilation-to-perfusion.
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Affiliation(s)
- Richard K Albert
- Chief of Medicine, Denver Health, Professor of Medicine, University of Colorado, Adjunct Professor of Engineering and Computer Science, University of Denver, Denver, Colorado, USA.
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149
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García-Prieto E, Amado-Rodríguez L, Albaiceta GM. [Monitorization of respiratory mechanics in the ventilated patient]. Med Intensiva 2013; 38:49-55. [PMID: 24199991 DOI: 10.1016/j.medin.2013.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 09/16/2013] [Indexed: 10/26/2022]
Abstract
Monitoring during mechanical ventilation allows the measurement of different parameters of respiratory mechanics. Accurate interpretation of these data can be useful for characterizing the situation of the different components of the respiratory system, and for guiding ventilator settings. In this review, we describe the basic concepts of respiratory mechanics, their interpretation, and their potential use in fine-tuning mechanical ventilation.
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Affiliation(s)
- E García-Prieto
- Servicio de Medicina Intensiva, Hospital Universitario Central de Asturias, Oviedo, España
| | - L Amado-Rodríguez
- Servicio de Medicina Intensiva, Hospital Universitario Central de Asturias, Oviedo, España; Departamento de Biología Funcional, Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo, Oviedo, España
| | - G M Albaiceta
- Servicio de Medicina Intensiva, Hospital Universitario Central de Asturias, Oviedo, España; Departamento de Biología Funcional, Instituto Universitario de Oncología del Principado de Asturias, Universidad de Oviedo, Oviedo, España; Centro de Investigación Biomédica en Red-Enfermedades Respiratorias, Instituto de Salud Carlos III, Madrid, España.
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150
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Spieth PM, Güldner A, Huhle R, Beda A, Bluth T, Schreiter D, Ragaller M, Gottschlich B, Kiss T, Jaber S, Pelosi P, Koch T, Gama de Abreu M. Short-term effects of noisy pressure support ventilation in patients with acute hypoxemic respiratory failure. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2013; 17:R261. [PMID: 24172538 PMCID: PMC4056040 DOI: 10.1186/cc13091] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Accepted: 10/11/2013] [Indexed: 01/12/2023]
Abstract
Introduction This study aims at comparing the very short-term effects of conventional and noisy (variable) pressure support ventilation (PSV) in mechanically ventilated patients with acute hypoxemic respiratory failure. Methods Thirteen mechanically ventilated patients with acute hypoxemic respiratory failure were enrolled in this monocentric, randomized crossover study. Patients were mechanically ventilated with conventional and noisy PSV, for one hour each, in random sequence. Pressure support was titrated to reach tidal volumes approximately 8 mL/kg in both modes. The level of positive end-expiratory pressure and fraction of inspired oxygen were kept unchanged in both modes. The coefficient of variation of pressure support during noisy PSV was set at 30%. Gas exchange, hemodynamics, lung functional parameters, distribution of ventilation by electrical impedance tomography, breathing patterns and patient-ventilator synchrony were analyzed. Results Noisy PSV was not associated with any adverse event, and was well tolerated by all patients. Gas exchange, hemodynamics, respiratory mechanics and spatial distribution of ventilation did not differ significantly between conventional and noisy PSV. Noisy PSV increased the variability of tidal volume (24.4 ± 7.8% vs. 13.7 ± 9.1%, P <0.05) and was associated with a reduced number of asynchrony events compared to conventional PSV (5 (0 to 15)/30 min vs. 10 (1 to 37)/30 min, P <0.05). Conclusions In the very short term, noisy PSV proved safe and feasible in patients with acute hypoxemic respiratory failure. Compared to conventional PSV, noisy PSV increased the variability of tidal volumes, and was associated with improved patient-ventilator synchrony, at comparable levels of gas exchange. Trial registration ClinicialTrials.gov, NCT00786292
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