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Sanchez AF, Ambrósio AM, Pinto ACBCF, Pereira MAA, Andrade FSRM, Rodrigues RR, de Carvalho Martins AR, Baroni CO, Ferrante B, Fantoni DT. Effects of a stepwise alveolar recruitment maneuver on lung volume distribution in dogs assessed by computed tomography. Front Vet Sci 2024; 10:1232635. [PMID: 38292132 PMCID: PMC10825017 DOI: 10.3389/fvets.2023.1232635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 12/19/2023] [Indexed: 02/01/2024] Open
Abstract
Background Pulmonary atelectasis is a commonly occurs during anesthesia. In these cases, mechanical ventilation (MV) associated with alveolar recruitment maneuvers (ARMs) and positive end-expiratory pressure (PEEP) is indicated to reverse the condition, ensure adequate gas exchange and improve oxygenation. ARMs can trigger volutrauma, barotrauma, and atelectrauma. Therefore, computed tomography (CT) is the gold-standard method for monitoring lung aeration after ARM. Objective To evaluate lung volume distribution after stepwise ARMs using computed tomography (CT). Methods Twelve dogs weighing 24.0 ± 6.0 kg, aged 3 ± 1 years, of both sexes and different breeds, underwent orchiectomy or ovariohysterectomy. The animals were anesthetized and ventilated in volume-controlled mode. ARMs were then initiated by positive end-expiratory pressure (PEEP) titration (5, 10, 15, and 20 cmH2O). CT scans, cardiovascular parameters, and ventilatory mechanics were evaluated at all time points. Data were assessed for normality using the Shapiro-Wilk test and a two-way analysis of variance, followed by a post-hoc Bonferroni test to identify differences between time points. Statistical significance was attributed to a value of p of <0.05. Results CT demonstrated that the ARMs increased ventilation throughout the lung, including the dependent regions, with volumes that increased and decreased proportionally with PEEP titration. When they reached PEEP 10 and 5 cmH2O descending (d), they remained significantly higher than those in PEEP 0 cmH2O (baseline). Static compliance improved about 40% at PEEP 10d and PEEP 5d compared to baseline. There was an increase in heart rate (HR) from PEEP 15 increasing (i) (74.5%) to PEEP 10d (54.8%) compared to baseline. Mean arterial blood pressure (MABP) decreased approximately 9% from PEEP 15i to PEEP 15d compared to baseline. Conclusion Lung attenuation and regional and global volumes assessed by CT showed that maximum pulmonary aeration distribution followed by PEEP titration occurred at PEEP 20 cmH2O, maintaining the lungs normoaerated and without hyperaeration.
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Affiliation(s)
- Ana Flávia Sanchez
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Aline Magalhães Ambrósio
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Ana Carolina B. C. Fonseca Pinto
- Department of Veterinary Clinical Sciences, Diagnostic Imaging Purdue University College of Veterinary Medicine, West Lafayette, IN, United States
| | - Marco Aurélio Amador Pereira
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, São Paulo, Brazil
| | | | - Renata Ramos Rodrigues
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, São Paulo, Brazil
| | | | - Carina Outi Baroni
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Bruno Ferrante
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, São Paulo, Brazil
| | - Denise Tabacchi Fantoni
- Department of Surgery, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, São Paulo, Brazil
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Prognostic value of computed tomographic findings in acute respiratory distress syndrome and the response to prone positioning. BMC Pulm Med 2022; 22:71. [PMID: 35216579 PMCID: PMC8874746 DOI: 10.1186/s12890-022-01864-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 02/15/2022] [Indexed: 01/06/2023] Open
Abstract
Background Prone positioning enables the redistribution of lung weight, leading to the improvement of gas exchange and respiratory mechanics. We aimed to evaluate whether the initial findings of acute respiratory distress syndrome (ARDS) on computed tomography (CT) are associated with the subsequent response to prone positioning in terms of oxygenation and 60-day mortality. Methods We retrospectively included patients who underwent prone positioning for moderate to severe ARDS from October 2014 to November 2020 at a medical center in Taiwan. A semiquantitative CT rating scale was used to quantify the extent of consolidation and ground-glass opacification (GGO) in the sternal, central and vertebral regions at three levels (apex, hilum and base) of the lungs. A prone responder was identified by a 20% increase in the ratio of arterial oxygen pressure (PaO2) to the fraction of oxygen (FiO2) or a 20 mmHg increase in PaO2. Results Ninety-six patients were included, of whom 68 (70.8%) were responders. Compared with nonresponders, responders had a significantly greater median dorsal–ventral difference in CT-consolidation scores (10 vs. 7, p = 0.046) but not in CT-GGO scores (− 1 vs. − 1, p = 0.974). Although dorsal–ventral differences in neither CT-consolidation scores nor CT-GGO scores were associated with 60-day mortality, high total CT-GGO scores (≥ 15) were an independent factor associated with 60-day mortality (odds ratio = 4.07, 95% confidence interval, 1.39–11.89, p = 0.010). Conclusions In patients with moderate to severe ARDS, a greater difference in the extent of consolidation along the dependent-independent axis on CT scan is associated with subsequent prone positioning oxygenation response, but not clinical outcome regarding survival. High total CT-GGO scores were independently associated with 60-day mortality. Supplementary Information The online version contains supplementary material available at 10.1186/s12890-022-01864-9.
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Wood C, Kataria V, Modrykamien AM. The acute respiratory distress syndrome. Proc (Bayl Univ Med Cent) 2020; 33:357-365. [PMID: 32675953 DOI: 10.1080/08998280.2020.1764817] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 03/27/2020] [Accepted: 04/06/2020] [Indexed: 12/18/2022] Open
Abstract
Acute respiratory distress syndrome (ARDS) is a prevalent cause of acute respiratory failure with high rates of mortality, as well as short- and long-term complications, such as physical and cognitive impairment. Therefore, early recognition of this syndrome and application of well-demonstrated therapeutic interventions are essential to change the natural course of this entity and bring about positive clinical outcomes. In this article, we review updated concepts in ARDS. Specifically, we discuss the current definition of ARDS, its risk factors, and the evidence supporting ventilation management, adjunctive therapies, and interventions required in refractory hypoxemia.
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Affiliation(s)
- Christopher Wood
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Baylor University Medical CenterDallasTexas
| | - Vivek Kataria
- Department of Pharmacy, Baylor University Medical CenterDallasTexas
| | - Ariel M Modrykamien
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Baylor University Medical CenterDallasTexas
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Haase J, Buchloh DC, Hammermüller S, Salz P, Mrongowius J, Carvalho NC, Beda A, Rau A, Starke H, Spieth PM, Gittel C, Muders T, Wrigge H, Reske AW. Mechanical Ventilation Strategies Targeting Different Magnitudes of Collapse and Tidal Recruitment in Porcine Acid Aspiration-Induced Lung Injury. J Clin Med 2019; 8:jcm8081250. [PMID: 31426607 PMCID: PMC6722815 DOI: 10.3390/jcm8081250] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 08/06/2019] [Accepted: 08/14/2019] [Indexed: 12/29/2022] Open
Abstract
Reducing ventilator-associated lung injury by individualized mechanical ventilation (MV) in patients with Acute Respiratory Distress Syndrome (ARDS) remains a matter of research. We randomly assigned 27 pigs with acid aspiration-induced ARDS to three different MV protocols for 24 h, targeting different magnitudes of collapse and tidal recruitment (collapse&TR): the ARDS-network (ARDSnet) group with low positive end-expiratory pressure (PEEP) protocol (permissive collapse&TR); the Open Lung Concept (OLC) group, PaO2/FiO2 >400 mmHg, indicating collapse&TR <10%; and the minimized collapse&TR monitored by Electrical Impedance Tomography (EIT) group, standard deviation of regional ventilation delay, SDRVD. We analyzed cardiorespiratory parameters, computed tomography (CT), EIT, and post-mortem histology. Mean PEEP over post-randomization measurements was significantly lower in the ARDSnet group at 6.8 ± 1.0 cmH2O compared to the EIT (21.1 ± 2.6 cmH2O) and OLC (18.7 ± 3.2 cmH2O) groups (general linear model (GLM) p < 0.001). Collapse&TR and SDRVD, averaged over all post-randomization measurements, were significantly lower in the EIT and OLC groups than in the ARDSnet group (collapse p < 0.001, TR p = 0.006, SDRVDp < 0.004). Global histological diffuse alveolar damage (DAD) scores in the ARDSnet group (10.1 ± 4.3) exceeded those in the EIT (8.4 ± 3.7) and OLC groups (6.3 ± 3.3) (p = 0.16). Sub-scores for edema and inflammation differed significantly (ANOVA p < 0.05). In a clinically realistic model of early ARDS with recruitable and nonrecruitable collapse, mechanical ventilation involving recruitment and high-PEEP reduced collapse&TR and resulted in improved hemodynamic and physiological conditions with a tendency to reduced histologic lung damage.
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Affiliation(s)
- Juliane Haase
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Leipzig, 04103 Leipzig, Germany
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, St. Georg Hospital, 04129 Leipzig, Germany
| | - Dorina C Buchloh
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Leipzig, 04103 Leipzig, Germany
- Department of Visceral, Transplantation, Vascular and Thoracic Surgery, University Hospital Leipzig, 04103 Leipzig, Germany
| | - Sören Hammermüller
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Leipzig, 04103 Leipzig, Germany
| | - Peter Salz
- Innovation Center Computer Assisted Surgery (ICCAS), University of Leipzig, Medical Faculty, 04103 Leipzig, Germany
| | - Julia Mrongowius
- Innovation Center Computer Assisted Surgery (ICCAS), University of Leipzig, Medical Faculty, 04103 Leipzig, Germany
| | - Nadja C Carvalho
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Leipzig, 04103 Leipzig, Germany
- Laboratory of Pneumology LIM09, Medical Faculty, São Paulo University, São Paulo 05508-060, Brazil
| | - Alessandro Beda
- Department of Electronic Engineering, Federal University of Minas Gerais, Belo Horizonte 31270-901, Brazil
| | - Anna Rau
- Department of Anesthesiology, University Medicine Göttingen, University of Göttingen, 37075 Göttingen, Germany
| | - Henning Starke
- Department of Anesthesiology and Intensive Care Medicine, Hannover Medical School, 30625 Hannover, Germany
| | - Peter M Spieth
- Department of Anesthesiology and Critical Care Medicine, University Hospital Dresden, Technische Universität Dresden, 01307 Dresden, Germany
| | - Claudia Gittel
- Department for Horses, University of Leipzig, 04103 Leipzig, Germany
| | - Thomas Muders
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, 53127 Bonn, Germany
| | - Hermann Wrigge
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Leipzig, 04103 Leipzig, Germany
- Department of Anesthesiology, Intensive Care and Emergency Medicine, Pain Therapy, Bergmannstrost Hospital Halle, 06112 Halle, Germany
| | - Andreas W Reske
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Leipzig, 04103 Leipzig, Germany.
- Innovation Center Computer Assisted Surgery (ICCAS), University of Leipzig, Medical Faculty, 04103 Leipzig, Germany.
- Department of Anesthesiology, Intensive Care Medicine, Emergency Medicine and Pain Therapy Heinrich-Braun-Hospital Zwickau, 08060 Zwickau, Germany.
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Volume Delivered During Recruitment Maneuver Predicts Lung Stress in Acute Respiratory Distress Syndrome. Crit Care Med 2016; 44:91-9. [PMID: 26474111 DOI: 10.1097/ccm.0000000000001355] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Global lung stress varies considerably with low tidal volume ventilation for acute respiratory distress syndrome. High stress despite low tidal volumes may worsen lung injury and increase risk of death. No widely available parameter exists to assess global lung stress. We aimed to determine whether the volume delivered during a recruitment maneuver (V(RM)) is inversely associated with lung stress and mortality in acute respiratory distress syndrome. DESIGN Substudy of an acute respiratory distress syndrome clinical trial on esophageal pressure-guided positive end-expiratory pressure titration. SETTING U.S. academic medical center. PATIENTS Forty-two patients with acute respiratory distress syndrome in whom airflow, airway pressure, and esophageal pressure were recorded during the recruitment maneuver. INTERVENTIONS A single recruitment maneuver was performed before initiating protocol-directed ventilator management. Recruitment maneuvers consisted of a 30-second breath hold at 40 cm H2O airway pressure under heavy sedation or paralysis. V(RM) was calculated by integrating the flow-time waveform during the maneuver. End-inspiratory stress was defined as the transpulmonary (airway minus esophageal) pressure during end-inspiratory pause of a tidal breath and tidal stress as the transpulmonary pressure difference between end-inspiratory and end-expiratory pauses. MEASUREMENTS AND MAIN RESULTS V(RM) ranged between 7.4 and 34.7 mL/kg predicted body weight. Lower V(RM) predicted high end-inspiratory and tidal lung stress (end-inspiratory: β = -0.449; 95% CI, -0.664 to -0.234; p < 0.001; tidal: β = -0.267; 95% CI, -0.423 to -0.111; p = 0.001). After adjusting for PaO2/FIO2 and either driving pressure, tidal volume, or plateau pressure and positive end-expiratory pressure, V(RM) remained independently associated with both end-inspiratory and tidal stress. In unadjusted analysis, low V(RM) predicted increased risk of death (odds ratio, 0.85; 95% CI, 0.72-1.00; p = 0.026). V(RM) remained significantly associated with mortality after adjusting for study arm (odds ratio, 0.84; 95% CI, 0.71-1.00; p = 0.022). CONCLUSIONS Low V(RM) independently predicts high lung stress and may predict risk of death in patients with acute respiratory distress syndrome.
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Abstract
PURPOSE OF REVIEW To provide an overview on most recent knowledge on methods currently available for monitoring of recruitment maneuvers at the bedside. RECENT FINDINGS The effects of recruitment maneuvers on clinical outcomes in patients with moderate to severe acute respiratory distress syndrome and in patients with healthy lungs undergoing major surgery were recently assessed. Despite being part of a multifaceted approach of protective ventilation, recruitment maneuvers are supposed to decrease mortality and improve postoperative outcomes. However, the role of recruitment maneuver remains controversial in routine practice owing to concerns regarding complications, especially its effects on hemodynamics. In addition, although recruitment maneuvers are being increasingly used, there remains a great deal of uncertainty regarding the precise way to evaluate the effect of recruitment.An effective recruitment maneuver is expected to reinflate nonaerated lung units. End-expiratory lung volume, compliance, dead space, volumetric capnography, and bedside imaging techniques such as lung ultrasound and electrical impedance tomography have all different strengths and weaknesses. A multimodal and multiparametric approach could be a valuable option for bedside monitoring of recruitment maneuvers both in the ICU and in the operative room. SUMMARY Several methods offer evaluation of lung recruitability and allow the monitoring of positive and negative effects of recruitment maneuvers. More than the type of method used, a multifaceted approach of monitoring of recruitment maneuvers should be regarded.
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Modrykamien AM, Gupta P. The acute respiratory distress syndrome. Proc (Bayl Univ Med Cent) 2015; 28:163-71. [PMID: 25829644 DOI: 10.1080/08998280.2015.11929219] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The acute respiratory distress syndrome (ARDS) is a major cause of acute respiratory failure. Its development leads to high rates of mortality, as well as short- and long-term complications, such as physical and cognitive impairment. Therefore, early recognition of this syndrome and application of demonstrated therapeutic interventions are essential to change the natural course of this devastating entity. In this review article, we describe updated concepts in ARDS. Specifically, we discuss the new definition of ARDS, its risk factors and pathophysiology, and current evidence regarding ventilation management, adjunctive therapies, and intervention required in refractory hypoxemia.
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Affiliation(s)
- Ariel M Modrykamien
- Division of Pulmonary and Critical Care Medicine, Baylor University Medical Center at Dallas, Dallas, Texas (Modrykamien), and the Division of Pulmonary, Sleep, and Critical Care Medicine, Creighton University Medical Center, Omaha, Nebraska (Gupta)
| | - Pooja Gupta
- Division of Pulmonary and Critical Care Medicine, Baylor University Medical Center at Dallas, Dallas, Texas (Modrykamien), and the Division of Pulmonary, Sleep, and Critical Care Medicine, Creighton University Medical Center, Omaha, Nebraska (Gupta)
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Zompatori M, Ciccarese F, Fasano L. Overview of current lung imaging in acute respiratory distress syndrome. Eur Respir Rev 2014; 23:519-30. [DOI: 10.1183/09059180.00001314] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Imaging plays a key role in the diagnosis and follow-up of acute respiratory distress syndrome (ARDS). Chest radiography, bedside lung ultrasonography and computed tomography scans can provide useful information for the management of patients and detection of prognostic factors. However, imaging findings are not specific and several possible differential diagnoses should be taken into account. Herein we will review the role of radiological techniques in ARDS, highlight the plain radiological and computed tomography findings according to the pathological stage of the disease (exudative, inflammatory and fibroproliferative), and summarise the main points for the differential diagnosis with cardiogenic oedema, which is still challenging in the acute stage.
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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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Beatmungskonzepte beim herzchirurgischen Patienten. ZEITSCHRIFT FUR HERZ THORAX UND GEFASSCHIRURGIE 2014. [DOI: 10.1007/s00398-014-1122-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Luks AM. Ventilatory strategies and supportive care in acute respiratory distress syndrome. Influenza Other Respir Viruses 2014; 7 Suppl 3:8-17. [PMID: 24215377 DOI: 10.1111/irv.12178] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
While antiviral therapy is an important component of care in patients with the acute respiratory distress syndrome (ARDS) following influenza infection, it is not sufficient to ensure good outcomes, and additional measures are usually necessary. Patients usually receive high levels of supplemental oxygen to counteract the hypoxemia resulting from severe gas exchange abnormalities. Many patients also receive invasive mechanical ventilation for support for oxygenation, while in resource-poor settings, supplemental oxygen via face mask may be the only available intervention. Patients with ARDS receiving mechanical ventilation should receive lung-protective ventilation, whereby tidal volume is decreased to 6 ml/kg of their predicted weight and distending pressures are maintained ≤ 30 cm H2 O, as well as increased inspired oxygen concentrations and positive end-expiratory pressure (PEEP) to prevent atelectasis and support oxygenation. While these measures are sufficient in most patients, a minority develop refractory hypoxemia and may receive additional therapies, including prone positioning, inhaled vasodilators, extracorporeal membrane oxygenation, recruitment maneuvers followed by high PEEP, and neuromuscular blockade, although recent data suggest that this last option may be warranted earlier in the clinical course before development of refractory hypoxemia. Application of these "rescue strategies" is complicated by the lack of guidance in the literature regarding implementation. While much attention is devoted to these strategies, clinicians must not lose sight of simple interventions that affect patient outcomes including head of bed elevation, prophylaxis against venous thromboembolism and gastrointestinal bleeding, judicious use of fluids in the post-resuscitative phase, and a protocol-based approach to sedation and spontaneous breathing trials.
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Affiliation(s)
- Andrew M Luks
- Division of Pulmonary and Critical Care Medicine and the International Respiratory and Severe Illness Center (INTERSECT), University of Washington, Seattle, WA, USA
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Cornejo RA, Díaz JC, Tobar EA, Bruhn AR, Ramos CA, González RA, Repetto CA, Romero CM, Gálvez LR, Llanos O, Arellano DH, Neira WR, Díaz GA, Zamorano AJ, Pereira GL. Effects of prone positioning on lung protection in patients with acute respiratory distress syndrome. Am J Respir Crit Care Med 2014; 188:440-8. [PMID: 23348974 DOI: 10.1164/rccm.201207-1279oc] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
RATIONALE Positive end-expiratory pressure (PEEP) and prone positioning may induce lung recruitment and affect alveolar dynamics in acute respiratory distress syndrome (ARDS). Whether there is interdependence between the effects of PEEP and prone positioning on these variables is unknown. OBJECTIVES To determine the effects of high PEEP and prone positioning on lung recruitment, cyclic recruitment/derecruitment, and tidal hyperinflation and how these effects are influenced by lung recruitability. METHODS Mechanically ventilated patients (Vt 6 ml/kg ideal body weight) underwent whole-lung computed tomography (CT) during breath-holding sessions at airway pressures of 5, 15, and 45 cm H2O and Cine-CTs on a fixed thoracic transverse slice at PEEP 5 and 15 cm H2O. CT images were repeated in supine and prone positioning. A recruitment maneuver at 45 cm H2O was performed before each PEEP change. Lung recruitability was defined as the difference in percentage of nonaerated tissue between 5 and 45 cm H2O. Cyclic recruitment/de-recruitment and tidal hyperinflation were determined as tidal changes in percentage of nonaerated and hyperinflated tissue, respectively. MEASUREMENTS AND MAIN RESULTS Twenty-four patients with ARDS were included. Increasing PEEP from 5 to 15 cm H2O decreased nonaerated tissue (501 ± 201 to 322 ± 132 grams; P < 0.001) and increased tidal-hyperinflation (0.41 ± 0.26 to 0.57 ± 0.30%; P = 0.004) in supine. Prone positioning further decreased nonaerated tissue (322 ± 132 to 290 ± 141 grams; P = 0.028) and reduced tidal hyperinflation observed at PEEP 15 in supine patients (0.57 ± 0.30 to 0.41 ± 0.22%). Cyclic recruitment/de-recruitment only decreased when high PEEP and prone positioning were applied together (4.1 ± 1.9 to 2.9 ± 0.9%; P = 0.003), particularly in patients with high lung recruitability. CONCLUSIONS Prone positioning enhances lung recruitment and decreases alveolar instability and hyperinflation observed at high PEEP in patients with ARDS.
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Affiliation(s)
- Rodrigo A Cornejo
- Unidad de Pacientes Críticos, Departamento de Medicina, Hospital Clínico Universidad de Chile, Santiago, Chile.
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Cruces P, Donoso A, Valenzuela J, Díaz F. Respiratory and hemodynamic effects of a stepwise lung recruitment maneuver in pediatric ARDS: a feasibility study. Pediatr Pulmonol 2013; 48:1135-43. [PMID: 23255291 DOI: 10.1002/ppul.22729] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2012] [Accepted: 10/17/2012] [Indexed: 11/06/2022]
Abstract
BACKGROUND Little is known about the efficacy and safety of recruitment maneuvers (RMs) in pediatric patients with acute respiratory distress syndrome (ARDS). We therefore assessed the effects on gas exchange and lung mechanics and the possible detrimental effects of a sequential lung RMs and decremental positive end-expiratory pressure (PEEP) titration in pediatric ARDS patients. METHODS We enrolled patients <15 years of age with ARDS, progressive hypoxemia, <72 hr of mechanical ventilation, and hemodynamic stability. A step-wise RM and decremental PEEP trial were performed. Safety was evaluated as the occurrence of hypotension and low pulse oxymeter oxygen saturation during the maneuver and development of airleaks after. Efficacy was evaluated as changes in lung compliance (Cdyn ) and gas exchange 1, 12, and 24 hr after the RM. RESULTS We included 25 patients, of median age 5 (1-16) months, median weight 7.0 (4.1-9.2) kg, median PaO2 /FIO2 117 (96-139), and median Cdyn 0.48 (0.41-0.68) ml/cmH2 O/kg at baseline. Thirty RM were performed, with all completed successfully. No airleaks developed. Mild hypotension was detected during four procedures. Following RM, Cdyn , and PaO2 /FIO2 increased significantly (P < 0.01 each), without changes in PaCO2 (P = 0.4). A >25% improvement in lung function (Cdyn or PaO2 /FIO2 ) was observed after 90% of the RM procedures. Gas exchange worsening over the next 24 hr resulted in HFOV use in 36% of patients, while the remaining subjects sustained improvements in oxygenation at 12 and 24 hr. The 28-day mortality rate was 16%. CONCLUSIONS Sequential RMs were safe and well tolerated in hemodynamically stable children with ARDS. RMs and a decremental PEEP trial may improve lung function in pediatric patients with ARDS and severe hypoxemia.
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Affiliation(s)
- Pablo Cruces
- Área de Cuidados Críticos, Hospital Padre Hurtado, Santiago, Chile; Department of Pediatrics, Facultad de Medicina Clínica Alemana Universidad del Desarrollo, Santiago, Chile
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Fan E, Villar J, Slutsky AS. Novel approaches to minimize ventilator-induced lung injury. BMC Med 2013; 11:85. [PMID: 23536968 PMCID: PMC3621434 DOI: 10.1186/1741-7015-11-85] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 02/07/2013] [Indexed: 02/06/2023] Open
Abstract
Despite over 40 years of research, there is no specific lung-directed therapy for the acute respiratory distress syndrome (ARDS). Although much has evolved in our understanding of its pathogenesis and factors affecting patient outcome, supportive care with mechanical ventilation remains the cornerstone of treatment. Perhaps the most important advance in ARDS research has been the recognition that mechanical ventilation, although necessary to preserve life, can itself aggravate or cause lung damage through a variety of mechanisms collectively referred to as ventilator-induced lung injury (VILI). This improved understanding of ARDS and VILI has been important in designing lung-protective ventilatory strategies aimed at attenuating VILI and improving outcomes. Considerable effort has been made to enhance our mechanistic understanding of VILI and to develop new ventilatory strategies and therapeutic interventions to prevent and ameliorate VILI with the goal of improving outcomes in patients with ARDS. In this review, we will review the pathophysiology of VILI, discuss a number of novel physiological approaches for minimizing VILI, therapies to counteract biotrauma, and highlight a number of experimental studies to support these concepts.
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Affiliation(s)
- Eddy Fan
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada.
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Schranz C, Docherty PD, Chiew YS, Chase JG, Möller K. Structural identifiability and practical applicability of an alveolar recruitment model for ARDS patients. IEEE Trans Biomed Eng 2012; 59:3396-404. [PMID: 22955868 DOI: 10.1109/tbme.2012.2216526] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Patient-specific mathematical models of respiratory mechanics can offer substantial insight into patient state and pulmonary dynamics that are not directly measurable. Thus, they offer significant potential to evaluate and guide patient-specific lung protective ventilator strategies for acute respiratory distress syndrome (ARDS) patients. To assure bedside applicability, the model must be computationally efficient and identifiable from the limited available data, while also capturing dominant dynamics and trends observed in ARDS patients. In this study, an existing static recruitment model is enhanced by considering alveolar distension and implemented in a novel time-continuous dynamic respiratory mechanics model. The model was tested for structural identifiability and a hierarchical gradient descent approach was used to fit the model to low-flow test responses of 12 ARDS patients. Finally, a comprehensive practical identifiability analysis was performed to evaluate the impact of data quality on the model parameters. Identified parameter values were physiologically plausible and very accurately reproduced the measured pressure responses. Structural identifiability of the model was proven, but practical identifiability analysis of the results showed a lack of convexity on the error surface indicating that successful parameter identification is currently not assured in all test sets. Overall, the model presented is physiologically and clinically relevant, captures ARDS dynamics, and uses clinically descriptive parameters. The patient-specific models show the ability to capture pulmonary dynamics directly relevant to patient condition and clinical guidance. These characteristics currently cannot be directly measured or established without such a validated model.
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Affiliation(s)
- Christoph Schranz
- Institute of Technical Medicine, Furtwangen University, D-78054 Villingen-Schwenningen, Germany.
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Boriosi JP, Cohen RA, Summers E, Sapru A, Hanson JH, Gildengorin G, Newman V, Flori HR, Flori HR. Lung aeration changes after lung recruitment in children with acute lung injury: a feasibility study. Pediatr Pulmonol 2012; 47:771-9. [PMID: 22298419 PMCID: PMC4169705 DOI: 10.1002/ppul.22508] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 12/17/2011] [Indexed: 11/12/2022]
Abstract
RATIONALE There are several adult studies using computed tomography (CT-scan) to examine lung aeration changes during or after a recruitment maneuver (RM) in ventilated patients with acute lung injury (ALI). However, there are no published data on the lung aeration changes during or after a RM in ventilated pediatric patients with ALI. OBJECTIVE To describe CT-scan lung aeration changes and gas exchange after lung recruitment in pediatric ALI and assess the safety of transporting patients in the acute phase of ALI to the CT-scanner. METHODS We present a case series completed in a subset of six patients enrolled in our previously published study of efficacy and safety of lung recruitment in pediatric patients with ALI. INTERVENTION RM using incremental positive end-expiratory pressure. RESULTS There was a variable increase in aerated and poorly aerated lung after the RM ranging from 3% to 72% (median 20%; interquartile range 6, 47; P = 0.03). All patients had improvement in the ratio of partial pressure of arterial oxygen over fraction of inspired oxygen (PaO(2) /FiO(2)) after the RM (median 14%; interquartile range: 8, 72; P = 0.03). There was a decrease in the partial pressure of arterial carbon dioxide (PaCO(2)) in four of six subjects after the RM (median -5%; interquartile range: -9, 2; P = 0.5). One subject had transient hypercapnia (41% increase in PaCO(2)) during the RM and this correlated with the smallest increase (3%) in aerated and poorly aerated lung. All patients tolerated the RM without hemodynamic compromise, barotrauma, hypoxemia, or dysrhythmias. CONCLUSIONS Lung recruitment results in improved lung aeration as detected by lung tomography. This is accompanied by improvements in oxygenation and ventilation. However, the clinical significance of these findings is uncertain. Transporting patients in early ALI to the CT-scanner seems safe and feasible.
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Affiliation(s)
- Juan P Boriosi
- Department of Pediatrics, University of Wisconsin-Madison, Madison, Wisconsin 53792-4108, USA.
| | | | | | | | | | | | | | | | - Heidi R. Flori
- Pediatric Critical Care, Children’s Hospital and Research Center Oakland, Oakland, California
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Positive end expiratory pressure in patients with acute respiratory distress syndrome – The past, present and future. Biomed Signal Process Control 2012. [DOI: 10.1016/j.bspc.2011.03.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Stefanidis K, Dimopoulos S, Tripodaki ES, Vitzilaios K, Politis P, Piperopoulos P, Nanas S. Lung sonography and recruitment in patients with early acute respiratory distress syndrome: a pilot study. Crit Care 2011; 15:R185. [PMID: 21816054 PMCID: PMC3387628 DOI: 10.1186/cc10338] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Revised: 06/28/2011] [Accepted: 08/04/2011] [Indexed: 02/07/2023] Open
Abstract
INTRODUCTION Bedside lung sonography is a useful imaging tool to assess lung aeration in critically ill patients. The purpose of this study was to evaluate the role of lung sonography in estimating the nonaerated area changes in the dependent lung regions during a positive end-expiratory pressure (PEEP) trial of patients with early acute respiratory distress syndrome (ARDS). METHODS Ten patients (mean ± standard deviation (SD): age 64 ± 7 years, Acute Physiology and Chronic Health Evaluation II (APACHE II) score 21 ± 4) with early ARDS on mechanical ventilation were included in the study. Transthoracic sonography was performed in all patients to depict the nonaerated area in the dependent lung regions at different PEEP settings of 5, 10 and 15 cm H2O. Lung sonographic assessment of the nonaerated lung area and arterial blood gas analysis were performed simultaneously at the end of each period. A control group of five early ARDS patients matched for APACHE II score was also included in the study. RESULTS The nonaerated areas in the dependent lung regions were significantly reduced during PEEP increases from 5 to 10 to 15 cm H2O (27 ± 31 cm2 to 20 ± 24 cm2 to 11 ± 12 cm2, respectively; P < 0.01). These changes were associated with a significant increase in arterial oxygen partial pressure (74 ± 15 mmHg to 90 ± 19 mmHg to 102 ± 26 mmHg; P < 0.001, respectively). No significant changes were observed in the nonaerated areas in the dependent lung regions in the control group. CONCLUSIONS In this study, we show that transthoracic lung sonography can detect the nonaerated lung area changes during a PEEP trial of patients with early ARDS. Thus, transthoracic lung sonography might be considered as a useful clinical tool in the management of ARDS patients.
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Affiliation(s)
| | - Stavros Dimopoulos
- 1st Critical Care Medicine Department, Evaggelismos Hospital, NKUA, Ipsilantou 45-47, 10676, Athens, Greece
| | - Elli-Sophia Tripodaki
- 1st Critical Care Medicine Department, Evaggelismos Hospital, NKUA, Ipsilantou 45-47, 10676, Athens, Greece
| | | | - Panagiotis Politis
- 1st Critical Care Medicine Department, Evaggelismos Hospital, NKUA, Ipsilantou 45-47, 10676, Athens, Greece
| | | | - Serafim Nanas
- 1st Critical Care Medicine Department, Evaggelismos Hospital, NKUA, Ipsilantou 45-47, 10676, Athens, Greece
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Abstract
OBJECTIVE To assess the safety and efficacy of a recruitment maneuver, the Open Lung Tool, in pediatric patients with acute lung injury and acute respiratory distress syndrome. DESIGN Prospective cohort study using a repeated-measures design. SETTING Pediatric intensive care unit at an urban tertiary children's hospital. PATIENTS Twenty-one ventilated pediatric patients with acute lung injury. INTERVENTION Recruitment maneuver using incremental positive end-expiratory pressure. MEASUREMENTS AND MAIN RESULTS The ratio of partial pressure of arterial oxygen over fraction of inspired oxygen (Pao2/Fio2 ratio) increased 53% immediately after the recruitment maneuver. The median Pao2/Fio2 ratio increased from 111 (interquartile range, 73-266) prerecruitment maneuver to 170 (interquartile range, 102-341) immediately postrecruitment maneuver (p < .01). Improvement in Pao2/Fio2 ratio persisted with an increase of 80% over the baseline at 4 hrs and 40% at 12 hrs after the recruitment maneuver. The median Pao2/Fio2 ratio was 200 (interquartile range, 116-257) 4 hrs postrecruitment maneuver (p < .05) and 156 (interquartile range, 127-236) 12 hrs postrecruitment maneuver (p < .01). Compared with prerecruitment maneuver, the partial pressure of arterial carbon dioxide (Paco2) was significantly decreased at 4 hrs postrecruitment maneuver but not immediately after the recruitment maneuver. The median Paco2 was 49 torr (interquartile range, 44-60) prerecruitment maneuver compared with 48 torr (interquartile range, 43-50) immediately postrecruitment maneuver (p = .69), 45 torr (interquartile range, 41-50) at 4 hrs postrecruitment maneuver (p < .01), and 43 torr (interquartile range, 38-51) at 12 hrs postrecruitment maneuver. Recruitment maneuvers were well tolerated except for significant increase in Paco2 in three patients. There were no serious adverse events related to the recruitment maneuver. CONCLUSIONS Using the modified open lung tool recruitment maneuver, pediatric patients with acute lung injury may safely achieve improved oxygenation and ventilation with these benefits potentially lasting up to 12 hrs postrecruitment maneuver.
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Zhang JG, Chen XJ, Liu F, Zeng ZG, Qian KJ. Lung recruitment maneuver effects on respiratory mechanics and extravascular lung water index in patients with acute respiratory distress syndrome. World J Emerg Med 2011; 2:201-5. [PMID: 25215010 PMCID: PMC4129705 DOI: 10.5847/wjem.j.1920-8642.2011.03.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2011] [Accepted: 06/26/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Animal experiments showed that recruitment maneuver (RM) and protective ventilation strategy of the lung could improve oxygenation and reduce extravascular lung water. This study was to investigate the effects of RM on respiratory mechanics and extravascular lung water index (EVLWI) in patients with acute respiratory distress syndrome (ARDS). METHODS Thirty patients with ARDS were randomized into a RM group and a non-RM group. In the RM group, after basic mechanical ventilation stabilized for 30 minutes, RM was performed and repeated once every 12 hours for 3 days. In the non-RM group, lung protective strategy was conducted without RM. Oxygenation index (PaO2/FiO2), peak inspiratory pressure (PIP), Plateau pressure (Pplat), static pulmonary compliance (Cst) and EVLWI of patients before treatment and at 12, 24, 48, 72 hours after the treatment were measured and compared between the groups. Hemodynamic changes were observed before and after RM. One-way ANOVA, Student's t test and Fisher's exact test were used to process the data. RESULTS The levels of PaO2/FiO2 and Cst increased after treatment in the two groups, but they were higher in the RM group than in the non-RM group (P<0.05). The PIP and Pplat decreased after treatment in the two groups, but they were lower in the RM group than in the non-RM group (P<0.05). The EVLWI in the two groups showed downward trend after treatment (P<0.05), and the differences were signifcant at all time points (P<0.01); the EVLWI in the RM group was lower than that in the non-RM group at 12, 24, 48 and 72 hours (P<0.05 or P<0.01). Compared with pre-RM, hemodynamics changes during RM were significantly different (P<0.01); compared with pre-RM, the changes were not significantly different at 120 seconds after the end of RM (P>0.05). CONCLUSIONS RM could reduce EVLWI, increase oxygenation and lung compliance. The effect of RM on hemodynamics was transient.
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Affiliation(s)
- Jian-guo Zhang
- ICU, People's Hospital of Linyi, Linyi 276000, China (Zhang JG, Chen XJ) ICU, First Affiliated Hospital of Nanchang University, Nanchang 330006, China (Liu F, Zeng ZG, Qian KJ)
| | - Xiao-juan Chen
- ICU, People's Hospital of Linyi, Linyi 276000, China (Zhang JG, Chen XJ) ICU, First Affiliated Hospital of Nanchang University, Nanchang 330006, China (Liu F, Zeng ZG, Qian KJ)
| | - Fen Liu
- ICU, People's Hospital of Linyi, Linyi 276000, China (Zhang JG, Chen XJ) ICU, First Affiliated Hospital of Nanchang University, Nanchang 330006, China (Liu F, Zeng ZG, Qian KJ)
| | - Zhen-guo Zeng
- ICU, People's Hospital of Linyi, Linyi 276000, China (Zhang JG, Chen XJ) ICU, First Affiliated Hospital of Nanchang University, Nanchang 330006, China (Liu F, Zeng ZG, Qian KJ)
| | - Ke-jian Qian
- ICU, People's Hospital of Linyi, Linyi 276000, China (Zhang JG, Chen XJ) ICU, First Affiliated Hospital of Nanchang University, Nanchang 330006, China (Liu F, Zeng ZG, Qian KJ)
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Kuzkov VV, Suborov EV, Kirov MY, Waerhaug K, Mortensen R, Kuklin VN, Nordhus KC, Bjertnaes LJ. Radiographic lung density assessed by computed tomography is associated with extravascular lung water content. Acta Anaesthesiol Scand 2010; 54:1018-26. [PMID: 20645924 DOI: 10.1111/j.1399-6576.2010.02272.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND We hypothesized that in acute lung injury (ALI), the volume of pulmonary tissue with aqueous density, as determined by spiral computed tomography (CT), is associated with extravascular lung water content. Our aim was to compare tissue volume index, as assessed by CT, before and after oleic acid-induced ALI, with extravascular lung water indexes (EVLWI), determined with single transpulmonary thermodilution (EVLWI(STD)), thermal-dye dilution (EVLWI(TDD)), and postmortem gravimetry (EVLWI(G)). METHODS Seven instrumented sheep received an intravenous infusion of oleic acid 0.08 ml/kg (OA group) and four animals had vehicle only (Control group). The day before, and immediately after the experiment, sheep were anesthetized to undergo quantitative CT examinations during a short breath hold. Hemodynamics, oxygenation, EVLWI(STD), and EVLW(TDD) were registered. Linear regression analysis was used to assess the relationships between EVLWI(STD), EVLW(TDD), EVLWI(G), and lung tissue volume index (TVI(CT)) determined with CT. RESULTS In the OA group, total lung volume increased compared with Controls. Poorly and non-aerated lung volumes increased a 3.6- and 4.9-fold, respectively, and TVI(CT) almost doubled. EVLWI(STD), EVLWI(TDD), and TVI(CT) were associated significantly with EVLWI(G) (r=0.85, 0.90, and 0.88, respectively; P<0.001). TVI(CT) deviated from the reference EVLWI(G) values to the greatest extent with a mean bias +/- 2SD of 4.0 +/- 6.0 ml/kg. CONCLUSIONS In ovine oleic acid-induced ALI, lung tissue volume, as assessed by quantitative CT, is in close agreement with EVLWI, as determined by indicator dilution methods and postmortem gravimetry, but overestimates lung fluid content.
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Affiliation(s)
- V V Kuzkov
- Department of Anaesthesiology, Institute of Clinical Medicine, Faculty of Health Sciences, University of Tromsø and University Hospital of North Norway, Tromsø, Norway
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Fan E, Wilcox ME, Brower RG, Stewart TE, Mehta S, Lapinsky SE, Meade MO, Ferguson ND. Recruitment maneuvers for acute lung injury: a systematic review. Am J Respir Crit Care Med 2008; 178:1156-63. [PMID: 18776154 DOI: 10.1164/rccm.200802-335oc] [Citation(s) in RCA: 203] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
RATIONALE There are conflicting data regarding the safety and efficacy of recruitment maneuvers (RMs) in patients with acute lung injury (ALI). OBJECTIVES To summarize the physiologic effects and adverse events in adult patients with ALI receiving RMs. METHODS Systematic review of case series, observational studies, and randomized clinical trials with pooling of study-level data. MEASUREMENTS AND MAIN RESULTS Forty studies (1,185 patients) met inclusion criteria. Oxygenation (31 studies; 636 patients) was significantly increased after an RM (PaO2): 106 versus 193 mm Hg, P = 0.001; and PaO2/FiO2 ratio: 139 versus 251 mm Hg, P < 0.001). There were no persistent, clinically significant changes in hemodynamic parameters after an RM. Ventilatory parameters (32 studies; 548 patients) were not significantly altered by an RM, except for higher PEEP post-RM (11 versus 16 cm H2O; P = 0.02). Hypotension (12%) and desaturation (9%) were the most common adverse events (31 studies; 985 patients). Serious adverse events (e.g., barotrauma [1%] and arrhythmias [1%]) were infrequent. Only 10 (1%) patients had their RMs terminated prematurely due to adverse events. CONCLUSIONS Adult patients with ALI receiving RMs experienced a significant increase in oxygenation, with few serious adverse events. Transient hypotension and desaturation during RMs is common but is self-limited without serious short-term sequelae. Given the uncertain benefit of transient oxygenation improvements in patients with ALI and the lack of information on their influence on clinical outcomes, the routine use of RMs cannot be recommended or discouraged at this time. RMs should be considered for use on an individualized basis in patients with ALI who have life-threatening hypoxemia.
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Affiliation(s)
- Eddy Fan
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
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Carvalho ARS, Jandre FC, Pino AV, Bozza FA, Salluh J, Rodrigues R, Ascoli FO, Giannella-Neto A. Positive end-expiratory pressure at minimal respiratory elastance represents the best compromise between mechanical stress and lung aeration in oleic acid induced lung injury. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2008; 11:R86. [PMID: 17688701 PMCID: PMC2206498 DOI: 10.1186/cc6093] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 04/03/2007] [Accepted: 08/09/2007] [Indexed: 11/10/2022]
Abstract
INTRODUCTION Protective ventilatory strategies have been applied to prevent ventilator-induced lung injury in patients with acute lung injury (ALI). However, adjustment of positive end-expiratory pressure (PEEP) to avoid alveolar de-recruitment and hyperinflation remains difficult. An alternative is to set the PEEP based on minimizing respiratory system elastance (Ers) by titrating PEEP. In the present study we evaluate the distribution of lung aeration (assessed using computed tomography scanning) and the behaviour of Ers in a porcine model of ALI, during a descending PEEP titration manoeuvre with a protective low tidal volume. METHODS PEEP titration (from 26 to 0 cmH2O, with a tidal volume of 6 to 7 ml/kg) was performed, following a recruitment manoeuvre. At each PEEP, helical computed tomography scans of juxta-diaphragmatic parts of the lower lobes were obtained during end-expiratory and end-inspiratory pauses in six piglets with ALI induced by oleic acid. The distribution of the lung compartments (hyperinflated, normally aerated, poorly aerated and non-aerated areas) was determined and the Ers was estimated on a breath-by-breath basis from the equation of motion of the respiratory system using the least-squares method. RESULTS Progressive reduction in PEEP from 26 cmH2O to the PEEP at which the minimum Ers was observed improved poorly aerated areas, with a proportional reduction in hyperinflated areas. Also, the distribution of normally aerated areas remained steady over this interval, with no changes in non-aerated areas. The PEEP at which minimal Ers occurred corresponded to the greatest amount of normally aerated areas, with lesser hyperinflated, and poorly and non-aerated areas. Levels of PEEP below that at which minimal Ers was observed increased poorly and non-aerated areas, with concomitant reductions in normally inflated and hyperinflated areas. CONCLUSION The PEEP at which minimal Ers occurred, obtained by descending PEEP titration with a protective low tidal volume, corresponded to the greatest amount of normally aerated areas, with lesser collapsed and hyperinflated areas. The institution of high levels of PEEP reduced poorly aerated areas but enlarged hyperinflated ones. Reduction in PEEP consistently enhanced poorly or non-aerated areas as well as tidal re-aeration. Hence, monitoring respiratory mechanics during a PEEP titration procedure may be a useful adjunct to optimize lung aeration.
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Affiliation(s)
- Alysson Roncally S Carvalho
- Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Av. Horácio Macedo, CT Bloco H-327, 2030, 21941-914, Rio de Janeiro, Brazil
| | - Frederico C Jandre
- Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Av. Horácio Macedo, CT Bloco H-327, 2030, 21941-914, Rio de Janeiro, Brazil
| | - Alexandre V Pino
- Biomedical Engineering Program, COPPE, Federal University of Rio de Janeiro, Av. Horácio Macedo, CT Bloco H-327, 2030, 21941-914, Rio de Janeiro, Brazil
| | - Fernando A Bozza
- Fundação Oswaldo Cruz, Instituto de Pesquisa Clinica Evandro Chagas e Laboratório de Imunofarmacologia, IOC, Av Brasil, 4365, Manguinhos, 21045-900 Rio de Janeiro, Brazil
| | - Jorge Salluh
- National Institute of Cancer-1, ICU, Praça Cruz Vermelha, 20230-130 Rio de Janeiro, Brazil
| | - Rosana Rodrigues
- Radiodiagnostic Service, Clementino Fraga Filho Hospital, Federal University of Rio de Janeiro, R Professor Rodolpho Paulo Rocco, 255, 21-941-913 Rio de Janeiro, Brazil
| | - Fabio O Ascoli
- Fundação Oswaldo Cruz, Instituto de Pesquisa Clinica Evandro Chagas e Laboratório de Imunofarmacologia, IOC, Av Brasil, 4365, Manguinhos, 21045-900 Rio de Janeiro, Brazil
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Ford NL, Martin EL, Lewis JF, Veldhuizen RAW, Drangova M, Holdsworth DW. In vivo characterization of lung morphology and function in anesthetized free-breathing mice using micro-computed tomography. J Appl Physiol (1985) 2007; 102:2046-55. [PMID: 17255374 DOI: 10.1152/japplphysiol.00629.2006] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lung morphology and function in human subjects can be monitored with computed tomography (CT). Because many human respiratory diseases are routinely modeled in rodents, a means of monitoring the changes in the structure and function of the rodent lung is desired. High-resolution images of the rodent lung can be attained with specialized micro-CT equipment, which provides a means of monitoring rodent models of lung disease noninvasively with a clinically relevant method. Previous studies have shown respiratory-gated images of intubated and respirated mice. Although the image quality and resolution are sufficient in these studies to make quantitative measurements, these measurements of lung structure will depend on the settings of the ventilator and not on the respiratory mechanics of the individual animals. In addition, intubation and ventilation can have unnatural effects on the respiratory dynamics of the animal, because the airway pressure, tidal volume, and respiratory rate are selected by the operator. In these experiments, important information about the symptoms of the respiratory disease being studied may be missed because the respiration is forced to conform to the ventilator settings. In this study, we implement a method of respiratory-gated micro-CT for use with anesthetized free-breathing rodents. From the micro-CT images, quantitative analysis of the structure of the lungs of healthy unconscious mice was performed to obtain airway diameters, lung and airway volumes, and CT densities at end expiration and during inspiration. Because the animals were free breathing, we were able to calculate tidal volume (0.09 +/- 0.03 ml) and functional residual capacity (0.16 +/- 0.03 ml).
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Affiliation(s)
- N L Ford
- Robarts Research Institute, London, ON, Canada N6A5K8.
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Kim HY, Lee KS, Kang EH, Suh GY, Kwon OJ, Chung MJ. Acute respiratory distress syndrome. Computed tomography findings and their applications to mechanical ventilation therapy. J Comput Assist Tomogr 2006; 28:686-96. [PMID: 15480046 DOI: 10.1097/01.rct.0000132792.28832.1a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In acute respiratory distress syndrome, computed tomography (CT) typically demonstrates symmetric ground-glass opacity and gravity-dependent consolidation when patients are positioned supine. Moreover, CT findings may vary according to the evolutional stage of the disease over time. The slope of the pressure-volume curve, which is a direct or indirect measure of lung recruitment rather than a measure of the characteristics of the respiratory mechanics of a portion of the aerated lung, indicates the potential for recruitment. The lung recruitment maneuver is performed by maintaining a sustained increase in airway pressure with the goal of opening collapsed alveoli, after which sufficient positive end-expiratory pressure is applied to maintain the alveoli in an open state. Alveolar recruitment resulting from continuous positive airway pressure occurs predominantly in nondependent and cephalic lung regions and is more limited in the diaphragmatic region or even negative (alveolar derecruitment) caudal to the diaphragmatic cupola. By partially relieving cardiac and abdominal compression, positioning patients in prone and semirecumbent positions may reopen dependent and caudal lung regions and improve gas exchange. The mean CT attenuation of a given region is equivalent to its aeration. Computed tomography, especially helical CT, may help to assess alveolar recruitment and lung overinflation by providing information on whole-lung attenuation.
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Affiliation(s)
- Ha Young Kim
- Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Abstract
Monitoring the functional and mechanical properties of the lungs during positive pressure ventilation may assist in confirming the underlying pulmonary diagnosis, allow therapeutic interventions to be accurately assessed and provide information that ensures the optimal setting of the ventilator parameters and encourages timely weaning. This article reviews the range of lung function measurements, both continuous and intermittent, that may be undertaken during mechanical ventilation. The monitoring capability of ICU ventilators is increasing in complexity.
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Affiliation(s)
- P D Macnaughton
- Critical Care Unit, Derriford Hospital, Plymouth PL6 8DH, UK.
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Albaiceta GM, Luyando LH, Parra D, Menendez R, Calvo J, Pedreira PR, Taboada F. Inspiratory vs. expiratory pressure-volume curves to set end-expiratory pressure in acute lung injury. Intensive Care Med 2005; 31:1370-8. [PMID: 16091965 DOI: 10.1007/s00134-005-2746-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2005] [Accepted: 07/03/2005] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To study the effects of two levels of positive end-expiratory pressure (PEEP), 2 cm H(2)O above the lower inflection point of the inspiratory limb and equal to the point of maximum curvature on the expiratory limb of the pressure-volume curve, in gas exchange, respiratory mechanics, and lung aeration. DESIGN AND SETTING Prospective clinical study in the intensive care unit and computed tomography ward of a university hospital. PATIENTS Eight patients with early acute lung injury. INTERVENTIONS Both limbs of the static pressure-volume curve were traced and inflection points calculated using a sigmoid model. During ventilation with a tidal volume of 6 ml/kg we sequentially applied a PEEP 2 cm H(2)O above the inspiratory lower inflection point (15.5+/-3.1 cm H(2)O) and a PEEP equal to the expiratory point of maximum curvature (23.5+/-4.1 cmH(2)O). MEASUREMENTS AND RESULTS Arterial blood gases, respiratory system compliance and resistance and changes in lung aeration (measured on three computed tomography slices during end-expiratory and end-inspiratory pauses) were measured at each PEEP level. PEEP according to the expiratory point of maximum curvature was related to an improvement in oxygenation, increase in normally aerated, decrease in nonaerated lung volumes, and greater alveolar stability. There was also an increase in PaCO(2), airway pressures, and hyperaerated lung volume. CONCLUSIONS High PEEP levels according to the point of maximum curvature of the deflation limb of the pressure-volume curve have both benefits and drawbacks.
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Affiliation(s)
- Guillermo M Albaiceta
- Department of Intensive Medicine, Hospital Universitario Central de Asturias, Celestino Villamil s/n, 33006 Oviedo, Spain.
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Medoff BD, Shepard JAO, Smith RN, Kratz A. Case records of the Massachusetts General Hospital. Case 17-2005. A 22-year-old woman with back and leg pain and respiratory failure. N Engl J Med 2005; 352:2425-34. [PMID: 15944428 DOI: 10.1056/nejmcpc059012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Benjamin D Medoff
- Pulmonary and Critical Care Unit, Center for Immunology and Inflammatory Diseases, Department of Medicine, Massachusetts General Hospital, USA
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Gattinoni L, Chiumello D, Biondetti P, Carlesso E. CT Ventilation Imaging. FUNCTIONAL LUNG IMAGING 2005. [DOI: 10.1201/b14155-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Abstract
ARDS or acute respiratory distress syndrome continues to be a considerable critical care challenge. Mortality has not decreased significantly over the last more than 30 years. This article presents an overview of origin, evaluation, and treatment of ARDS. Recent findings relative to onset and precipitators of ARDS have led to changes in evaluation and treatment plans. Clinical and radiologic descriptors in assessment of the patient with ARDS are discussed. Ventilatory modes and nursing interventions to optimize patient outcomes are identified. The challenges of outcomes issues presented offer opportunities for further study.
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Affiliation(s)
- Cynthia Kane
- Suburban Lung Associates, Elk Grove Village, IL 60007, USA.
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Albaiceta GM, Taboada F, Parra D, Luyando LH, Calvo J, Menendez R, Otero J. Tomographic Study of the Inflection Points of the Pressure–Volume Curve in Acute Lung Injury. Am J Respir Crit Care Med 2004; 170:1066-72. [PMID: 15317670 DOI: 10.1164/rccm.200312-1644oc] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The inflection points of the pressure-volume curve have been used for setting mechanical ventilation in patients with acute lung injury. However, the lung status at these points has never been specifically addressed. In 12 patients with early lung injury we traced both limbs of the pressure-volume curve by means of a stepwise change in airway pressure, and a computed tomography (CT) scan slice was obtained for every pressure level. Although aeration (increase in normally aerated lung) and recruitment (decrease in nonaerated lung) were parallel and continuous along the pressure axis during inflation, loss of aeration and derecruitment were only significant at pressures below the point of maximum curvature on the deflation limb of the pressure-volume curve. This point was related to a higher amount of normally aerated tissue and a lower amount of nonaerated tissue when compared with the lower inflection point on both limbs of the curve. Aeration at the inflection points was similar in lung injury from pulmonary or extrapulmonary origin. There were no significant changes in hyperinflated lung tissue. These results support the use of the deflation limb of the pressure-volume curve for positive end-expiratory pressure setting in patients with acute lung injury.
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Affiliation(s)
- Guillermo M Albaiceta
- Department of Intensive Medicine, Hospital Universitario Central de Asturias, Oveido, Spain.
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Abraham E, Andrews P, Antonelli M, Brochard L, Brun-Buisson C, Dobb G, Fagon JY, Groeneveld J, Mancebo J, Metnitz P, Nava S, Pinsky M, Radermacher P, Ranieri M, Richard C, Tasker R, Vallet B. Year in review in Intensive Care Medicine-2003. Part 1: Respiratory failure, infection and sepsis. Intensive Care Med 2004; 30:1017-31. [PMID: 15170528 DOI: 10.1007/s00134-004-2321-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2004] [Indexed: 11/25/2022]
Affiliation(s)
- Edward Abraham
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, University of Colorado Health Sciences Center, Denver, CO, USA
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Henzler D, Dembinski R, Kopp R, Hawickhorst R, Rossaint R, Kuhlen R. [Treatment of acute respiratory distress syndrome in a treatment center. Success is dependent on risk factors]. Anaesthesist 2004; 53:235-43. [PMID: 14999396 DOI: 10.1007/s00101-004-0653-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
SUBJECT Mortality rates remain high for the acute respiratory distress syndrome (ARDS) despite standardised treatment algorithms. Little is known about prognostic factors and exclusion criteria for advanced treatment including extracorporeal membrane oxygenation (ECMO). METHODS In an observational study design a cohort of 93 patients with severe ARDS admitted to a referral centre were analysed according to ventilatory and vital parameters. RESULTS Overall survival rate was 70% and in patients who received ECMO treatment it was 67%. In patients exhibiting relevant co-morbidity the odds ratio for fatal outcome increased to 4.7 (95% CI: 3.3-24.9), and patients with multiple organ failure had a 7.5-fold increase (95% CI: 2.3-25.2) for risk of death. Survivors demonstrated a more pronounced improvement in oxygenation ( p<0.05) and CO(2) removal ( p<0.05) than non-survivors. CONCLUSIONS Advanced treatment of ARDS including ECMO represents a therapeutic option if none of the currently considered contraindications are present. An improvement in gas exchange parameters, but not a defined value per se may be useful as a prognostic factor for favourable outcome.
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Affiliation(s)
- D Henzler
- Klinik für Anästhesiologie, Universitätsklinikum Aachen.
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Schreiter D, Reske A, Stichert B, Seiwerts M, Bohm SH, Kloeppel R, Josten C. Alveolar recruitment in combination with sufficient positive end-expiratory pressure increases oxygenation and lung aeration in patients with severe chest trauma. Crit Care Med 2004; 32:968-75. [PMID: 15071387 DOI: 10.1097/01.ccm.0000120050.85798.38] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Investigation of oxygenation and lung aeration during mechanical ventilation according to the open lung concept in patients with acute lung injury or acute respiratory distress syndrome. DESIGN Retrospective analysis. SETTING Surgical intensive care unit of a university hospital. PATIENTS We retrospectively identified 17 patients with acute lung injury/acute respiratory distress syndrome due to pulmonary contusion who had thoracic helical computed tomography scans before and after ventilation with the open lung concept. INTERVENTIONS Baseline ventilation consisted of low tidal volumes (< or =6 mL/kg) and positive end-expiratory pressure (PEEP; 5-17 cm H2O). We briefly applied high inspiratory pressures for opening up collapsed alveoli. External PEEP and intrinsic PEEP were combined to keep recruited lung units open. We generated intrinsic PEEP by pressure-cycled high-frequency inverse ratio ventilation (80 min, inspiratory/expiratory ratio 2:1) and maintained our ventilatory strategy for 24 hrs. Then, after reducing total PEEP by decreasing respiratory rate, Pao2/Fio2 ratio was reevaluated. If it remained >300 mm Hg, weaning was started. If not, previous ventilator settings were resumed for another 24 hrs after recruiting the lungs once again. MEASUREMENTS AND MAIN RESULTS Physiologic variables and ventilator settings were obtained from routine charts. Data from computed tomography before and after the open lung concept were analyzed for volumetric quantification of lung aeration and collapse. All results are presented as median and range. During baseline ventilation, PEEP was 10 (range, 5-17) cm H2O and after recruitment 21 (range, 18-26) cm H2O. Opening pressures were 65 (range, 50-80) cm H2O. After recruitment, Pao2/Fio2 ratio was higher in all patients. Total lung volume increased from 2915 (range, 1952-4941) to 4247 (range, 2285-6355) mL and normally aerated volume from 1742 (range, 774-2941) to 2971 (range, 1270-5232) mL. Atelectasis decreased significantly from 604 (range, 147-1538) to 106 (range, 0-736) mL. Hyperinflation increased significantly from 5 (range, 0-188) to 62 (range, 1-424) mL, whereas poor aeration did not change substantially from 649 (range, 302-1292) to 757 (range, 350-1613) mL. No hemodynamic problems occurred. CONCLUSIONS Lung recruitment increased arterial oxygenation, normally aerated lung volume, and total lung volume while decreasing the amount of collapsed tissue. These results indicate that the open lung concept is a reasonable mode of ventilation for patients with severe chest trauma.
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Affiliation(s)
- Dierk Schreiter
- Surgical Intensive Care Unit, Department of Surgery, University Hospital Leipzig, Leipzig, Germany.
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