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Penarrubia L, Verstraete A, Orkisz M, Davila E, Boussel L, Yonis H, Mezidi M, Dhelft F, Danjou W, Bazzani A, Sigaud F, Bayat S, Terzi N, Girard M, Bitker L, Roux E, Richard JC. Precision of CT-derived alveolar recruitment assessed by human observers and a machine learning algorithm in moderate and severe ARDS. Intensive Care Med Exp 2023; 11:8. [PMID: 36797424 PMCID: PMC9934943 DOI: 10.1186/s40635-023-00495-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 01/24/2023] [Indexed: 02/18/2023] Open
Abstract
BACKGROUND Assessing measurement error in alveolar recruitment on computed tomography (CT) is of paramount importance to select a reliable threshold identifying patients with high potential for alveolar recruitment and to rationalize positive end-expiratory pressure (PEEP) setting in acute respiratory distress syndrome (ARDS). The aim of this study was to assess both intra- and inter-observer smallest real difference (SRD) exceeding measurement error of recruitment using both human and machine learning-made lung segmentation (i.e., delineation) on CT. This single-center observational study was performed on adult ARDS patients. CT were acquired at end-expiration and end-inspiration at the PEEP level selected by clinicians, and at end-expiration at PEEP 5 and 15 cmH2O. Two human observers and a machine learning algorithm performed lung segmentation. Recruitment was computed as the weight change of the non-aerated compartment on CT between PEEP 5 and 15 cmH2O. RESULTS Thirteen patients were included, of whom 11 (85%) presented a severe ARDS. Intra- and inter-observer measurements of recruitment were virtually unbiased, with 95% confidence intervals (CI95%) encompassing zero. The intra-observer SRD of recruitment amounted to 3.5 [CI95% 2.4-5.2]% of lung weight. The human-human inter-observer SRD of recruitment was slightly higher amounting to 5.7 [CI95% 4.0-8.0]% of lung weight, as was the human-machine SRD (5.9 [CI95% 4.3-7.8]% of lung weight). Regarding other CT measurements, both intra-observer and inter-observer SRD were close to zero for the CT-measurements focusing on aerated lung (end-expiratory lung volume, hyperinflation), and higher for the CT-measurements relying on accurate segmentation of the non-aerated lung (lung weight, tidal recruitment…). The average symmetric surface distance between lung segmentation masks was significatively lower in intra-observer comparisons (0.8 mm [interquartile range (IQR) 0.6-0.9]) as compared to human-human (1.0 mm [IQR 0.8-1.3] and human-machine inter-observer comparisons (1.1 mm [IQR 0.9-1.3]). CONCLUSIONS The SRD exceeding intra-observer experimental error in the measurement of alveolar recruitment may be conservatively set to 5% (i.e., the upper value of the CI95%). Human-machine and human-human inter-observer measurement errors with CT are of similar magnitude, suggesting that machine learning segmentation algorithms are credible alternative to humans for quantifying alveolar recruitment on CT.
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Affiliation(s)
- Ludmilla Penarrubia
- grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, INSERM, CREATIS UMR 5220, U1294, Université de Lyon, Villeurbanne, France
| | - Aude Verstraete
- grid.413852.90000 0001 2163 3825Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004 Lyon, France
| | - Maciej Orkisz
- grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, INSERM, CREATIS UMR 5220, U1294, Université de Lyon, Villeurbanne, France
| | - Eduardo Davila
- grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, INSERM, CREATIS UMR 5220, U1294, Université de Lyon, Villeurbanne, France
| | - Loic Boussel
- grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, INSERM, CREATIS UMR 5220, U1294, Université de Lyon, Villeurbanne, France ,grid.413852.90000 0001 2163 3825Service de Radiologie, Hôpital De La Croix Rousse, Hospices Civils de Lyon, Lyon, France
| | - Hodane Yonis
- grid.413852.90000 0001 2163 3825Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004 Lyon, France
| | - Mehdi Mezidi
- grid.413852.90000 0001 2163 3825Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004 Lyon, France
| | - Francois Dhelft
- grid.413852.90000 0001 2163 3825Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004 Lyon, France ,grid.7849.20000 0001 2150 7757Université de Lyon, Université Claude Bernard Lyon 1, Villeurbanne, France
| | - William Danjou
- grid.413852.90000 0001 2163 3825Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004 Lyon, France
| | - Alwin Bazzani
- grid.413852.90000 0001 2163 3825Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004 Lyon, France
| | - Florian Sigaud
- grid.410529.b0000 0001 0792 4829Service de Médecine-Intensive Réanimation, CHU Grenoble-Alpes, Grenoble, France
| | - Sam Bayat
- grid.450307.50000 0001 0944 2786Synchrotron Radiation for Biomedicine Laboratory (STROBE), INSERM UA07, Univ. Grenoble Alpes, Grenoble, France ,grid.410529.b0000 0001 0792 4829Department of Pulmonology and Physiology, Grenoble University Hospital, Grenoble, France
| | - Nicolas Terzi
- grid.411154.40000 0001 2175 0984Maladies Infectieuses et Réanimation Médicale, CHU Rennes, Rennes, France ,grid.410368.80000 0001 2191 9284Faculté de Médecine, Biosit, Université Rennes1, Rennes, France ,grid.410368.80000 0001 2191 9284INSERM-CIC-1414, Faculté de Médecine, IFR 140, Université Rennes I, Rennes, France
| | - Mehdi Girard
- grid.413852.90000 0001 2163 3825Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004 Lyon, France
| | - Laurent Bitker
- grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, INSERM, CREATIS UMR 5220, U1294, Université de Lyon, Villeurbanne, France ,grid.413852.90000 0001 2163 3825Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004 Lyon, France
| | - Emmanuel Roux
- grid.7849.20000 0001 2150 7757Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, INSERM, CREATIS UMR 5220, U1294, Université de Lyon, Villeurbanne, France
| | - Jean-Christophe Richard
- Université Claude Bernard Lyon 1, INSA-Lyon, CNRS, INSERM, CREATIS UMR 5220, U1294, Université de Lyon, Villeurbanne, France. .,Service de Médecine Intensive Réanimation, Hôpital de la Croix Rousse, Hospices Civils de Lyon, 103 Grande Rue de La Croix Rousse, 69004, Lyon, France.
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Perchiazzi G, Larina A, Hansen T, Frithiof R, Hultström M, Lipcsey M, Pellegrini M. Chest dual-energy CT to assess the effects of steroids on lung function in severe COVID-19 patients. Crit Care 2022; 26:328. [PMID: 36284360 PMCID: PMC9595078 DOI: 10.1186/s13054-022-04200-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 10/12/2022] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Steroids have been shown to reduce inflammation, hypoxic pulmonary vasoconstriction (HPV) and lung edema. Based on evidence from clinical trials, steroids are widely used in severe COVID-19. However, the effects of steroids on pulmonary gas volume and blood volume in this group of patients are unexplored. OBJECTIVE Profiting by dual-energy computed tomography (DECT), we investigated the relationship between the use of steroids in COVID-19 and distribution of blood volume as an index of impaired HPV. We also investigated whether the use of steroids influences lung weight, as index of lung edema, and how it affects gas distribution. METHODS Severe COVID-19 patients included in a single-center prospective observational study at the intensive care unit at Uppsala University Hospital who had undergone DECT were enrolled in the current study. Patients' cohort was divided into two groups depending on the administration of steroids. From each patient's DECT, 20 gas volume maps and the corresponding 20 blood volume maps, evenly distributed along the cranial-caudal axis, were analyzed. As a proxy for HPV, pulmonary blood volume distribution was analyzed in both the whole lung and the hypoinflated areas. Total lung weight, index of lung edema, was estimated. RESULTS Sixty patients were analyzed, whereof 43 received steroids. Patients not exposed to steroids showed a more extensive non-perfused area (19% vs 13%, p < 0.01) and less homogeneous pulmonary blood volume of hypoinflated areas (kurtosis: 1.91 vs 2.69, p < 0.01), suggesting a preserved HPV compared to patients treated with steroids. Moreover, patients exposed to steroids showed a significantly lower lung weight (953 gr vs 1140 gr, p = 0.01). A reduction in alveolar-arterial difference of oxygen followed the treatment with steroids (322 ± 106 mmHg at admission vs 267 ± 99 mmHg at DECT, p = 0.04). CONCLUSIONS The use of steroids might cause impaired HPV and might reduce lung edema in severe COVID-19. This is consistent with previous findings in other diseases. Moreover, a reduced lung weight, as index of decreased lung edema, and a more homogeneous distribution of gas within the lung were shown in patients treated with steroids. TRIAL REGISTRATION Clinical Trials ID: NCT04316884, Registered March 13, 2020.
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Affiliation(s)
- Gaetano Perchiazzi
- grid.8993.b0000 0004 1936 9457Anesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden ,grid.8993.b0000 0004 1936 9457Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Akademiska Sjukhuset, Ing 40, 3 tr, 751 85 Uppsala, Sweden ,grid.412354.50000 0001 2351 3333Department of Anesthesia, Operation and Intensive Care, Uppsala University Hospital, Uppsala, Sweden
| | - Aleksandra Larina
- grid.8993.b0000 0004 1936 9457Anesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden ,grid.412354.50000 0001 2351 3333Department of Anesthesia, Operation and Intensive Care, Uppsala University Hospital, Uppsala, Sweden
| | - Tomas Hansen
- grid.8993.b0000 0004 1936 9457Section of Radiology, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Robert Frithiof
- grid.8993.b0000 0004 1936 9457Anesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden ,grid.412354.50000 0001 2351 3333Department of Anesthesia, Operation and Intensive Care, Uppsala University Hospital, Uppsala, Sweden
| | - Michael Hultström
- grid.8993.b0000 0004 1936 9457Anesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden ,grid.412354.50000 0001 2351 3333Department of Anesthesia, Operation and Intensive Care, Uppsala University Hospital, Uppsala, Sweden ,grid.8993.b0000 0004 1936 9457Integrative Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Miklos Lipcsey
- grid.8993.b0000 0004 1936 9457Anesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden ,grid.8993.b0000 0004 1936 9457Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Akademiska Sjukhuset, Ing 40, 3 tr, 751 85 Uppsala, Sweden ,grid.412354.50000 0001 2351 3333Department of Anesthesia, Operation and Intensive Care, Uppsala University Hospital, Uppsala, Sweden
| | - Mariangela Pellegrini
- grid.8993.b0000 0004 1936 9457Anesthesiology and Intensive Care Medicine, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden ,grid.8993.b0000 0004 1936 9457Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Akademiska Sjukhuset, Ing 40, 3 tr, 751 85 Uppsala, Sweden ,grid.412354.50000 0001 2351 3333Department of Anesthesia, Operation and Intensive Care, Uppsala University Hospital, Uppsala, Sweden
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Regli A, Ahmadi-Noorbakhsh S, Musk GC, Reese DJ, Herrmann P, Firth MJ, Pillow JJ. Computed tomographic assessment of lung aeration at different positive end-expiratory pressures in a porcine model of intra-abdominal hypertension and lung injury. Intensive Care Med Exp 2021; 9:52. [PMID: 34608559 PMCID: PMC8489364 DOI: 10.1186/s40635-021-00416-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 09/21/2021] [Indexed: 11/18/2022] Open
Abstract
Background Intra-abdominal hypertension (IAH) is common in critically ill patients and is associated with increased morbidity and mortality. High positive end-expiratory pressures (PEEP) can reverse lung volume and oxygenation decline caused by IAH, but its impact on alveolar overdistension is less clear. We aimed to find a PEEP range that would be high enough to reduce atelectasis, while low enough to minimize alveolar overdistention in the presence of IAH and lung injury. Methods Five anesthetized pigs received standardized anesthesia and mechanical ventilation. Peritoneal insufflation of air was used to generate intra-abdominal pressure of 27 cmH2O. Lung injury was created by intravenous oleic acid. PEEP levels of 5, 12, 17, 22, and 27 cmH2O were applied. We performed computed tomography and measured arterial oxygen levels, respiratory mechanics, and cardiac output 5 min after each new PEEP level. The proportion of overdistended, normally aerated, poorly aerated, and non-aerated atelectatic lung tissue was calculated based on Hounsfield units. Results PEEP decreased the proportion of poorly aerated and atelectatic lung, while increasing normally aerated lung. Overdistension increased with each incremental increase in applied PEEP. “Best PEEP” (respiratory mechanics or oxygenation) was higher than the “optimal CT inflation PEEP range” (difference between lower inflection points of atelectatic and overdistended lung) in healthy and injured lungs. Conclusions Our findings in a large animal model suggest that titrating a PEEP to respiratory mechanics or oxygenation in the presence of IAH is associated with increased alveolar overdistension. Supplementary Information The online version contains supplementary material available at 10.1186/s40635-021-00416-5.
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Affiliation(s)
- Adrian Regli
- Department of Intensive Care, Fiona Stanley Hospital, Murdoch Drive, Murdoch, WA, 6150, Australia. .,Medical School, Division of Emergency Medicine, The University of Western Australia, 35 Stirling Highway, Crawley, 6009, Australia. .,Medical School, The University of Notre Dame Australia, 19 Mouat Street, Fremantle, 6959, Australia. .,School of Human Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, 6009, Australia.
| | - Siavash Ahmadi-Noorbakhsh
- School of Human Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, 6009, Australia
| | - Gabrielle Christine Musk
- Animal Care Services, The University of Western Australia, 35 Stirling Highway, Crawley, 6009, Australia.,School of Veterinary and Life Sciences, Murdoch University, Nyarrie Drive, Murdoch, 6150, Australia
| | - David Joseph Reese
- VetCT Consultants in Telemedicine PTY LTD, 185-187 High Street, Fremantle, 6160, Australia
| | - Peter Herrmann
- Department of Anaesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Martin Joseph Firth
- Centre for Applied Statistics, Department of Mathematics and Statistics, The University of Western Australia, 35 Stirling Highway, Crawley, 6009, Australia
| | - J Jane Pillow
- School of Human Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, 6009, Australia
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4
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Pellegrini M, Larina A, Mourtos E, Frithiof R, Lipcsey M, Hultström M, Segelsjö M, Hansen T, Perchiazzi G. A quantitative analysis of extension and distribution of lung injury in COVID-19: a prospective study based on chest computed tomography. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2021; 25:276. [PMID: 34348797 PMCID: PMC8334337 DOI: 10.1186/s13054-021-03685-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 07/09/2021] [Indexed: 01/08/2023]
Abstract
Background Typical features differentiate COVID-19-associated lung injury from acute respiratory distress syndrome. The clinical role of chest computed tomography (CT) in describing the progression of COVID-19-associated lung injury remains to be clarified. We investigated in COVID-19 patients the regional distribution of lung injury and the influence of clinical and laboratory features on its progression. Methods This was a prospective study. For each CT, twenty images, evenly spaced along the cranio-caudal axis, were selected. For regional analysis, each CT image was divided into three concentric subpleural regions of interest and four quadrants. Hyper-, normally, hypo- and non-inflated lung compartments were defined. Nonparametric tests were used for hypothesis testing (α = 0.05). Spearman correlation test was used to detect correlations between lung compartments and clinical features. Results Twenty-three out of 111 recruited patients were eligible for further analysis. Five hundred-sixty CT images were analyzed. Lung injury, composed by hypo- and non-inflated areas, was significantly more represented in subpleural than in core lung regions. A secondary, centripetal spread of lung injury was associated with exposure to mechanical ventilation (p < 0.04), longer spontaneous breathing (more than 14 days, p < 0.05) and non-protective tidal volume (p < 0.04). Positive fluid balance (p < 0.01), high plasma D-dimers (p < 0.01) and ferritin (p < 0.04) were associated with increased lung injury. Conclusions In a cohort of COVID-19 patients with severe respiratory failure, a predominant subpleural distribution of lung injury is observed. Prolonged spontaneous breathing and high tidal volumes, both causes of patient self-induced lung injury, are associated to an extensive involvement of more central regions. Positive fluid balance, inflammation and thrombosis are associated with lung injury. Trial registration Study registered a priori the 20th of March, 2020. Clinical Trials ID NCT04316884. Supplementary Information The online version contains supplementary material available at 10.1186/s13054-021-03685-4.
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Affiliation(s)
- Mariangela Pellegrini
- Anesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Akademiska sjukhuset, Uppsala, Sweden.,Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Aleksandra Larina
- Anesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Akademiska sjukhuset, Uppsala, Sweden
| | - Evangelos Mourtos
- Radiology, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Robert Frithiof
- Anesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Akademiska sjukhuset, Uppsala, Sweden
| | - Miklos Lipcsey
- Anesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Akademiska sjukhuset, Uppsala, Sweden.,Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Michael Hultström
- Anesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Akademiska sjukhuset, Uppsala, Sweden.,Integrative Physiology, Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Monica Segelsjö
- Radiology, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Tomas Hansen
- Radiology, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden
| | - Gaetano Perchiazzi
- Anesthesiology and Intensive Care, Department of Surgical Sciences, Uppsala University, Akademiska sjukhuset, Uppsala, Sweden. .,Hedenstierna Laboratory, Department of Surgical Sciences, Uppsala University, Uppsala, Sweden.
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Erdem A, Gedikli E, Yersal N, Karaismailoglu S, Muftuoglu S, Fadillioglu E, Tuncer M. Protective role of erdosteine pretreatment on oleic acid–induced acute lung injury. J Surg Res 2017; 213:234-242. [DOI: 10.1016/j.jss.2017.02.061] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/12/2017] [Accepted: 02/24/2017] [Indexed: 11/24/2022]
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Salman AE, Yetişir F, Kılıç M, Onal O, Dostbil A, Zeybek D, Aksoy M, Kaymak F, Celik T, Unver S. The impact of pretreatment with bolus dose of enteral glutamine on acute lung injury induced by oleic acid in rats. J Anesth 2013; 28:354-62. [PMID: 24271996 DOI: 10.1007/s00540-013-1745-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/30/2013] [Indexed: 01/29/2023]
Abstract
PURPOSE Both parenteral and enteral glutamine have shown beneficial effects in sepsis and ischemia/reperfusion-induced acute lung injury (ALI). Oleic acid (OA) has been used to induce ALI in experimental studies. In this study, we investigated the effects of pretreatment of a bolus dose of enteral glutamine on ALI induced by OA in rats. METHODS Twenty-eight adult female Sprague-Dawley rats weighing 240-300 g were divided into four groups, 7 in each. Group I and group II received normal saline for 30 days, group III and group IV received glutamine at a dose of 1 g/kg for 10 days by gavage, and in group II and group IV 100 mg/kg OA was administered i.v. Histopathological examination of the lung was performed with light and electron microscopy. Levels of protein carbonyl, malondialdehyde, superoxide dismutase, catalase, and glutathione peroxidase levels were measured in tissue samples. Levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-10, and total tissue oxidant status and total tissue antioxidant status were measured in serum samples. RESULTS Light microscopy showed that the total lung injury score of group IV was significantly lower than group II. Change in thickness of the fused basal lamina was not significantly different in groups II and IV under electron microscopy. TNF-α, IL-6, and IL-10 serum levels were higher in group II when compared to group I and significantly attenuated in group IV. CONCLUSION Pretreatment with a bolus dose of enteral glutamine minimized the extent of ALI induced by OA in rats.
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Affiliation(s)
- A Ebru Salman
- Anesthesiology and Reanimation Department, Atatürk Research and Training Hospital, Ankara, Turkey
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Jambrik Z, Gargani L, Adamicza A, Kaszaki J, Varga A, Forster T, Boros M, Picano E. B-lines quantify the lung water content: a lung ultrasound versus lung gravimetry study in acute lung injury. ULTRASOUND IN MEDICINE & BIOLOGY 2010; 36:2004-2010. [PMID: 21030138 DOI: 10.1016/j.ultrasmedbio.2010.09.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2010] [Revised: 07/20/2010] [Accepted: 09/03/2010] [Indexed: 05/30/2023]
Abstract
B-lines (also termed ultrasound lung comets) obtained with lung ultrasound detect experimental acute lung injury (ALI) very early and before hemogasanalytic changes, with a simple, noninvasive, nonionizing and real-time method. Our aim was to estimate the correlation between B-lines number and the wet/dry ratio of the lung tissue, measured by gravimetry, in an experimental model of ALI. Seventeen Na-pentobarbital anesthetized, cannulated (central vein and carotid artery) minipigs were studied: five sham-operated animals served as controls and, in 12 animals, ALI was induced by injection of oleic acid (0.1 mL/kg) via the central venous catheter. B-lines were measured by echographic scanner in four predetermined chest scanning sites in each animal. At the end of each experiment, both lungs were dissected, weighed and dried to determine wet/dry weight ratio by gravimetry. After the injection of oleic acid, B-lines number increased over time. A significant correlation was found between the wet/dry ratio and B-lines number (r = 0.91, p < 0.001). These data suggest that in an experimental pig model of ALI/ARDS, B-lines assessed by lung ultrasound provide a simple, semiquantitative, noninvasive index of lung water accumulation, strongly correlated to invasive gravimetric assessment.
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Affiliation(s)
- Zoltán Jambrik
- 2nd Department of Medicine and Cardiology Centre, University of Sciences, Szeged, Hungary
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8
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Extrapolation from ten sections can make CT-based quantification of lung aeration more practicable. Intensive Care Med 2010; 36:1836-44. [PMID: 20689909 DOI: 10.1007/s00134-010-2014-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2010] [Accepted: 04/26/2010] [Indexed: 10/19/2022]
Abstract
PURPOSE Clinical applications of quantitative computed tomography (qCT) in patients with pulmonary opacifications are hindered by the radiation exposure and by the arduous manual image processing. We hypothesized that extrapolation from only ten thoracic CT sections will provide reliable information on the aeration of the entire lung. METHODS CTs of 72 patients with normal and 85 patients with opacified lungs were studied retrospectively. Volumes and masses of the lung and its differently aerated compartments were obtained from all CT sections. Then only the most cranial and caudal sections and a further eight evenly spaced sections between them were selected. The results from these ten sections were extrapolated to the entire lung. The agreement between both methods was assessed with Bland-Altman plots. RESULTS Median (range) total lung volume and mass were 3,738 (1,311-6,768) ml and 957 (545-3,019) g, the corresponding bias (limits of agreement) were 26 (-42 to 95) ml and 8 (-21 to 38) g, respectively. The median volumes (range) of differently aerated compartments (percentage of total lung volume) were 1 (0-54)% for the nonaerated, 5 (1-44)% for the poorly aerated, 85 (28-98)% for the normally aerated, and 4 (0-48)% for the hyperaerated subvolume. The agreement between the extrapolated results and those from all CT sections was excellent. All bias values were below 1% of the total lung volume or mass, the limits of agreement never exceeded ± 2%. CONCLUSION The extrapolation method can reduce radiation exposure and shorten the time required for qCT analysis of lung aeration.
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Hanson A, Göthberg S, Nilsson K, Larsson LE, Hedenstierna G. VTCO2 and dynamic compliance-guided lung recruitment in surfactant-depleted piglets: a computed tomography study. Pediatr Crit Care Med 2009; 10:687-92. [PMID: 19451840 DOI: 10.1097/pcc.0b013e3181a703cc] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Using computed tomography (CT) as reference, our primary objectives were to test if maximal tidal elimination of carbon dioxide (VTCO2) could be used as a marker of "optimal recruitment," indicating maximal available lung tissue for gas exchange and if a decrease in dynamic compliance (Cdyn) indicated the beginning of lung collapse during a downward positive end-expiratory pressure (PEEP) titration. DESIGN Prospective laboratory animal investigation. SETTING Clinical physiology research laboratory. SUBJECTS Six piglets undergoing lung lavage. INTERVENTIONS Saline-lavaged piglets were initially ventilated without PEEP at a tidal volume (VT) of 10 mL/kg followed by baseline ventilation at end-inspiratory pressure (EIP) 25 cm H2O and PEEP 6 cm H2O. PEEP was increased to 12 or 15 cm H2O. Then EIP was increased in steps of 5 cm H2O and the EIP where VTCO2 peaked or leveled off was assumed to define optimally recruited lungs. A downward PEEP titration followed from 12 or 15 to 4 cm H2O in steps of 1 cm H2O. First decline of Cdyn was assumed to define onset of lung collapse. VTCO2 and Cdyn were continuously recorded and CT scans iterated for each change of ventilation. "Open-lung PEEP" was set 2 cm H2O above PEEP at the first Cdyn decline and was used for a final period of "open-lung ventilation." MEASUREMENTS AND MAIN RESULTS CT images showed recruited lungs at peak VTCO2 and that a minimal amount of normally aerated lung was added by further increase in EIP. Cdyn declined just before CT scans indicated lung collapse. Compared with baseline, the target VT of 10 mL/kg was achieved at lower EIP and pressure amplitude (EIP-PEEP) during the final open-lung ventilation with more normally aerated and fewer collapsed lungs. Cdyn was doubled after recruitment. CONCLUSIONS The lung recruitment maneuver was effective and lungs optimally recruited at maximal VTCO2. A fall in Cdyn indicated lung collapse during downward PEEP titration as confirmed by CT.
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Affiliation(s)
- Angela Hanson
- Department of Paediatric Anaesthesia and Intensive Care, The Queen Silvia Children's Hospital, University of Gothenburg, Göteborg, Sweden.
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10
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Abstract
We report a case of multisystem organ failure after large volume subcutaneous injection of castor oil for cosmetic enhancement. An unlicensed practitioner injected 500 mL of castor oil bilaterally to the hips and buttocks of a 28-year-old male to female transsexual. Immediate local pain and erythema were followed by abdominal and chest pain, emesis, headache, hematuria, jaundice, and tinnitus. She presented to an emergency department 12 hours postinjection. Persistently hemolyzed blood samples complicated preliminary laboratory analysis. She rapidly deteriorated despite treatment and developed fever, tachycardia, hemolysis, thrombocytopenia, hepatitis, respiratory distress, and anuric renal failure. An infectious diseases evaluation was negative. After intensive supportive care, including mechanical ventilation and hemodialysis, she was discharged 11 days later, requiring dialysis for an additional 1.5 months. Castor oil absorption was inferred from recovery of the Ricinus communis biomarker, ricinine, in the patient's urine (41 ng/mL). Clinicians should anticipate multiple complications after unapproved methods of cosmetic enhancement.
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Fagerberg A, Stenqvist O, Aneman A. Electrical impedance tomography applied to assess matching of pulmonary ventilation and perfusion in a porcine experimental model. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2009; 13:R34. [PMID: 19265527 PMCID: PMC2689466 DOI: 10.1186/cc7741] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 11/27/2008] [Accepted: 03/05/2009] [Indexed: 11/10/2022]
Abstract
INTRODUCTION Electrical impedance tomography (EIT) can be used to measure impedance changes related to the thoracic content of air and blood. Few studies, however, have utilised EIT to make concurrent measurements of ventilation and perfusion. This experimental study was performed to investigate the feasibility of EIT to describe ventilation/perfusion (V/Q) matching after acute changes of pulmonary perfusion and aeration. METHODS Six mechanically ventilated, anaesthetised pigs in the supine position were studied at baseline, after inflation of a balloon in the inferior caval vein (Binfl) to reduce cardiac output and after an increased positive end-expiratory pressure (PEEP) of 20 cmH2O (PEEP20) to increase pulmonary aeration. EIT measurements were performed at the mid-thoracic level to measure the amplitude of impedance changes related to ventilation (ZV) and perfusion (ZQ), both globally and in four defined regions of interest (ROI) extending from the ventral to dorsal distance. RESULTS A largely parallel distribution of ZV and ZQ in all four ROIs during baseline conditions corresponded to a bell-shaped frequency distribution of ZV/ZQ ratios with only moderate scatter. Binfl and PEEP20 with unchanged tidal volumes significantly increased the mismatch of regional ZV and ZQ, the scatter of ZV/ZQ ratios and the heterogeneity of the ZV/ZQ frequency distribution. Significant positive and negative correlations were demonstrated between fractional alveolar dead space (r2 = 0.63 [regression coefficient]) and venous admixture (r2 = 0.48), respectively, and the global ZV/ZQ ratio. CONCLUSIONS EIT may be used to monitor the distribution of pulmonary ventilation and perfusion making detailed studies of V/Q matching possible.
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Affiliation(s)
- Anneli Fagerberg
- Department of Anaesthesiology and Intensive Care, The Sahlgrenska Academy, Bla Straket 5, Gothenburg, SE 413 45, Sweden
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Kasim I, Gulyas M, Almgren B, Högman M. A recruitment breath manoeuvre directly after endotracheal suction improves lung function: an experimental study in pigs. Ups J Med Sci 2009; 114:129-35. [PMID: 19736601 PMCID: PMC2852766 DOI: 10.1080/03009730903177357] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Atelectasis occurs after a well performed endotracheal suction. Clinical studies have shown that recruitment manoeuvres added after endotracheal suction during mechanical ventilation restore lung function. Repetitive lung over-distension is, however, harmful for the lung, and the effects of adding a larger breath, recruitment breath, directly after repeated endotracheal suction were therefore investigated. METHODS Twelve healthy anaesthetized pigs were randomized into two groups: one without and one with a recruitment breath manoeuvre (RBM), i.e. a breath 15 cmH(2)O above inspiratory pressure for 10 s during pressure-controlled ventilation. The pigs were suctioned every hour for 4 hours with an open suction system. RESULTS At the end of the study there was a statistically significant difference between the group given RBM and that without with respect to PaCO(2), tidal volume (V(T)), and compliance (Crs). Without RBM, the PaCO(2) increased from 4.6+/-0.4 to 6.1+/-1.5 kPa, V(T) decreased from 345+/-39 to 247+/-71 mL, and Crs decreased from 28+/-6 to 18+/-5 mL/cmH(2)O. There was no change in PaCO(2) or Crs when a RBM was given. Morphological analysis revealed no differences in aeration of apical and central lung parenchyma. In the basal lung parenchyma there were, however, greater areas with normal lung parenchyma and less atelectasis after RBM. CONCLUSIONS Atelectasis created by endotracheal suction can be opened by inflating the lung for a short duration with low pressure, without over-distension, immediately after suction.
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Affiliation(s)
| | | | - Birgitta Almgren
- 3Karolinska Institute, Department of Clinical Sciences, Division of Anaesthesia and Intensive Care, Danderyd University HospitalStockholmSweden
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Gargani L, Lionetti V, Di Cristofano C, Bevilacqua G, Recchia FA, Picano E. Early detection of acute lung injury uncoupled to hypoxemia in pigs using ultrasound lung comets. Crit Care Med 2007; 35:2769-74. [PMID: 17828031 DOI: 10.1097/01.ccm.0000287525.03140.3f] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Oleic acid-induced lung injury is an established experimental model of acute lung injury in pigs and is considered to reproduce the early exudative phase of acute respiratory distress syndrome. Ultrasound lung comets are an echographic sign of extravascular lung water, originating from thickened interlobular septa. The objective of this study was to evaluate the timing and relationship between the number of ultrasound lung comets, the Pao2/Fio2 ratio, and the static respiratory compliance in an experimental model of oleic acid-induced lung injury in pigs. DESIGN Laboratory experiment. SETTING Research institute. SUBJECTS Ten anesthetized pigs. INTERVENTIONS Acute lung injury was induced by injection of oleic acid (0.1 mL/kg, intravenously). Ultrasound lung comets, Pao2/Fio2, and static respiratory compliance were measured at baseline and at 15, 30, 60, and 90 mins after the injection of oleic acid. We evaluated ultrasound lung comets by transthoracic echography (7.5-MHz vascular probe), scanning on right and left hemithoraxes at 12 predefined scanning sites. MEASUREMENTS AND MAIN RESULTS Acute lung injury/acute respiratory distress syndrome was present in all pigs at 90 mins. The number of ultrasound lung comets increased over time and was consistently earlier than the decrease in Pao2/Fio2. At 15 mins, ultrasound lung comets were markedly increased, but no significant changes in Pao2/Fio2 were observed. Accordingly, static respiratory compliance was dramatically reduced at 15 mins compared with baseline (17.04 +/- 1.82 vs. 34.84 +/- 2.62 mL/cm H2O, p < .05). CONCLUSIONS Ultrasound lung comets, assessed by transthoracic echography, detected extravascular lung water accumulation very early in the course of the oleic acid lung injury in pigs, in the presence of a normal Pao2/Fio2. These results suggest that ultrasound lung comets could be a very early, noninvasive, and simple method to detect and quantify pulmonary edema in acute lung injury.
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Affiliation(s)
- Luna Gargani
- Institute of Clinical Physiology, National Research Council, Pisa, Italy.
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14
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Early detection of acute lung injury uncoupled to hypoxemia in pigs using ultrasound lung comets *. Crit Care Med 2007. [DOI: 10.1097/00003246-200712000-00015] [Citation(s) in RCA: 2] [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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Karmrodt J, Bletz C, Yuan S, David M, Heussel CP, Markstaller K. Quantification of atelectatic lung volumes in two different porcine models of ARDS †. Br J Anaesth 2006; 97:883-95. [PMID: 17046849 DOI: 10.1093/bja/ael275] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Cyclic recruitment during mechanical ventilation contributes to ventilator associated lung injury. Two different pathomechanisms in acute respiratory distress syndrome (ARDS) are currently discussed: alveolar collapse vs persistent flooding of small airways and alveoli. We compare two different ARDS animal models by computed tomography (CT) to describe different recruitment and derecruitment mechanisms at different airway pressures: (i) lavage-ARDS, favouring alveolar collapse by surfactant depletion; and (ii) oleic acid ARDS, favouring alveolar flooding by capillary leakage. METHODS In 12 pigs [25 (1) kg], ARDS was randomly induced, either by saline lung lavage or oleic acid (OA) injection, and 3 animals served as controls. A respiratory breathhold manoeuvre without spontaneous breathing at different continuous positive airway pressure (CPAP) was applied in random order (CPAP levels of 5, 10, 15, 30, 35 and 50 cm H(2)O) and spiral-CT scans of the total lung were acquired at each CPAP level (slice thickness=1 mm). In each spiral-CT the volume of total lung parenchyma, tissue, gas, non-aerated, well-aerated, poorly aerated, and over-aerated lung was calculated. RESULTS In both ARDS models non-aerated lung volume decreased significantly from CPAP 5 to CPAP 50 [oleic acid lung injury (OAI): 346.9 (80.1) to 96.4 (48.8) ml, P<0.001; lavage-ARDS: 245 17.6) to 42.7 (4.8) ml, P<0.001]. In lavage-ARDS poorly aerated lung volume decreased at higher CPAP levels [232 (45.2) at CPAP 10 to 84 (19.4) ml at CPAP 50, P<0.001] whereas in OAI poorly aerated lung volume did not vary at different airway pressures. CONCLUSIONS In both ARDS models well-aerated and non-aerated lung volume respond to different CPAP levels in a comparable fashion: Thus, a cyclical alveolar collapse seems to be part of the derecruitment process also in the OA-ARDS. In OA-ARDS, the increase in poorly aerated lung volume reflects the specific initial lesion, that is capillary leakage with interstitial and alveolar oedema.
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Affiliation(s)
- J Karmrodt
- Department of Anaesthesiology, Johannes Gutenberg-University, Mainz, Germany.
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Lindgren S, Odenstedt H, Olegård C, Söndergaard S, Lundin S, Stenqvist O. Regional lung derecruitment after endotracheal suction during volume- or pressure-controlled ventilation: a study using electric impedance tomography. Intensive Care Med 2006; 33:172-80. [PMID: 17072587 DOI: 10.1007/s00134-006-0425-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2006] [Accepted: 09/19/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE To assess lung volume and compliance changes during open- and closed-system suctioning using electric impedance tomography (EIT) during volume- or pressure-controlled ventilation. DESIGN AND SETTING Experimental study in a university research laboratory. SUBJECTS Nine bronchoalveolar saline-lavaged pigs. INTERVENTIONS Open and closed suctioning using a 14-F catheter in volume- or pressure-controlled ventilation at tidal volume 10 ml/kg, respiratory rate 20 breaths/min, and positive end-expiratory pressure 10 cmH2O. MEASUREMENTS AND RESULTS Lung volume was monitored by EIT and a modified N2 washout/-in technique. Airway pressure was measured via a pressure line in the endotracheal tube. In four ventral-to-dorsal regions of interest regional ventilation and compliance were calculated at baseline and 30 s and 1, 2, and 10 min after suctioning. Blood gases were followed. At disconnection functional residual capacity (FRC) decreased by 58+/-24% of baseline and by a further 22+/-10% during open suctioning. Arterial oxygen tension decreased to 59+/-14% of baseline value 1 min after open suctioning. Regional compliance deteriorated most in the dorsal parts of the lung. Restitution of lung volume and compliance was significantly slower during pressure-controlled than volume-controlled ventilation. CONCLUSIONS EIT can be used to monitor rapid lung volume changes. The two dorsal regions of the lavaged lungs are most affected by disconnection and suctioning with marked decreases in compliance. Volume-controlled ventilation can be used to rapidly restitute lung aeration and oxygenation after lung collapse induced by open suctioning.
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Affiliation(s)
- Sophie Lindgren
- Department of Anesthesia and Intensive Care, Sahlgrenska University Hospital, 41345, Gothenburg, Sweden.
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Terragni PP, Rosboch G, Tealdi A, Corno E, Menaldo E, Davini O, Gandini G, Herrmann P, Mascia L, Quintel M, Slutsky AS, Gattinoni L, Ranieri VM. Tidal hyperinflation during low tidal volume ventilation in acute respiratory distress syndrome. Am J Respir Crit Care Med 2006; 175:160-6. [PMID: 17038660 DOI: 10.1164/rccm.200607-915oc] [Citation(s) in RCA: 504] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
RATIONALE Tidal volume and plateau pressure limitation decreases mortality in acute respiratory distress syndrome. Computed tomography demonstrated a small, normally aerated compartment on the top of poorly aerated and nonaerated compartments that may be hyperinflated by tidal inflation. OBJECTIVES We hypothesized that despite tidal volume and plateau pressure limitation, patients with a larger nonaerated compartment are exposed to tidal hyperinflation of the normally aerated compartment. MEASUREMENTS AND MAIN RESULTS Pulmonary computed tomography at end-expiration and end-inspiration was obtained in 30 patients ventilated with a low tidal volume (6 ml/kg predicted body weight). Cluster analysis identified 20 patients in whom tidal inflation occurred largely in the normally aerated compartment (69.9 +/- 6.9%; "more protected"), and 10 patients in whom tidal inflation occurred largely within the hyperinflated compartments (63.0 +/- 12.7%; "less protected"). The nonaerated compartment was smaller and the normally aerated compartment was larger in the more protected patients than in the less protected patients (p = 0.01). Pulmonary cytokines were lower in the more protected patients than in the less protected patients (p < 0.05). Ventilator-free days were 7 +/- 8 and 1 +/- 2 d in the more protected and less protected patients, respectively (p = 0.01). Plateau pressure ranged between 25 and 26 cm H(2)O in the more protected patients and between 28 and 30 cm H(2)O in the less protected patients (p = 0.006). CONCLUSIONS Limiting tidal volume to 6 ml/kg predicted body weight and plateau pressure to 30 cm H(2)O may not be sufficient in patients characterized by a larger nonaerated compartment.
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Affiliation(s)
- Pier Paolo Terragni
- Università di Torino, Dipartimento di Anestesiologia e Rianimazione, Ospedale S. Giovanni Battista-Molinette, Corso Dogliotti 14, 10126 Turin, Italy
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Wrigge H, Zinserling J, Neumann P, Muders T, Magnusson A, Putensen C, Hedenstierna G. Spontaneous breathing with airway pressure release ventilation favors ventilation in dependent lung regions and counters cyclic alveolar collapse in oleic-acid-induced lung injury: a randomized controlled computed tomography trial. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2005; 9:R780-9. [PMID: 16356227 PMCID: PMC1414014 DOI: 10.1186/cc3908] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2005] [Revised: 10/06/2005] [Accepted: 10/19/2005] [Indexed: 01/02/2023]
Abstract
Introduction Experimental and clinical studies have shown a reduction in intrapulmonary shunt with spontaneous breathing during airway pressure release ventilation (APRV) in acute lung injury. This reduction was related to reduced atelectasis and increased aeration. We hypothesized that spontaneous breathing will result in better ventilation and aeration of dependent lung areas and in less cyclic collapse during the tidal breath. Methods In this randomized controlled experimental trial, 22 pigs with oleic-acid-induced lung injury were randomly assigned to receive APRV with or without spontaneous breathing at comparable airway pressures. Four hours after randomization, dynamic computed tomography scans of the lung were obtained in an apical slice and in a juxtadiaphragmatic transverse slice. Analyses of regional attenuation were performed separately in nondependent and dependent halves of the lungs on end-expiratory scans and end-inspiratory scans. Tidal changes were assessed as differences between inspiration and expiration of the mechanical breaths. Results Whereas no differences were observed in the apical slices, spontaneous breathing resulted in improved tidal ventilation of dependent lung regions (P < 0.05) and less cyclic collapse (P < 0.05) in the juxtadiaphragmatic slices. In addition, with spontaneous breathing, the end-expiratory aeration increased and nonaerated tissue decreased in dependent lung regions close to the diaphragm (P < 0.05 for the interaction ventilator mode and lung region). Conclusion Spontaneous breathing during APRV redistributes ventilation and aeration to dependent, usually well-perfused, lung regions close to the diaphragm, and may thereby contribute to improved arterial oxygenation. Spontaneous breathing also counters cyclic collapse, which is a risk factor for ventilation-associated lung injury.
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Affiliation(s)
- Hermann Wrigge
- Department of Anaesthesiology and Intensive Care Medicine, University of Bonn, Sigmund-Freud-Strasse 25, D-53105 Bonn, Germany.
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Zinserling J, Wrigge H, Neumann P, Muders T, Magnusson A, Hedenstierna G, Putensen C. Methodologic Aspects of Attenuation Distributions From Static and Dynamic Thoracic CT Techniques in Experimental Acute Lung Injury. Chest 2005; 128:2963-70. [PMID: 16236973 DOI: 10.1378/chest.128.4.2963] [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: 11/01/2022] Open
Abstract
BACKGROUND In acute lung injury, thoracic CT is used to gain information about lung aeration and consolidation. This can be done either during breath-holding by spiral CT scanning of the entire lung or dynamically by scanning lung slices without interrupting ventilation. We hypothesized that attenuation distribution is dependent on static or dynamic scanning techniques. We also studied whether a variation in the CT cut level, corresponding to the diaphragm movement over a breath, had any effect on the attenuation distribution. METHODS Twenty-two pigs with oleic acid-induced lung injury were randomly assigned to receive pressure-controlled mechanical ventilation with or without spontaneous breathing. Transversal dynamic CT scans of the chest were performed in apical and juxtadiaphragmatic regions, and end-expiratory and end-inspiratory slices were selected. In addition, after clamping the tube at end-expiration and end-inspiration, respectively, spiral CTs were performed. Guided by morphologic structures, spiral CT slices matching the dynamic scan slice and three additional neighbored slices above the diaphragm were selected. Distributions of CT attenuation were calculated and summarized in ranges for comparison. RESULTS No significant difference in attenuation distributions between the two scanning methods or an interaction with the factors ventilation mode, ventilation phase, and attenuation range were found. In addition, attenuation distributions of four neighbored juxtadiaphragmatic slices, 8 mm thick, from the spiral CT did not differ statistically. CONCLUSION In an animal model of oleic acid-induced lung injury, analyses of transverse thoracic slices based on dynamic or static CT scanning showed comparable distributions of attenuation. Variations on the CT cut level of 24 mm had no significant effect on the distribution of Hounsfield unit numbers. CT attenuation distributions of transversal juxtadiaphragmatic slices were not dependent on exact position.
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Affiliation(s)
- Jörg Zinserling
- Department of Anesthesiology and Intensive Care Medicine, University of Bonn, D-53105, Bonn, Germany.
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