Bhushan H Katira1,2,3,4,5, Kohei Osada1,2, Doreen Engelberts1, Luca Bastia1,2,6, L Felipe Damiani1,2,7, Xuehan Li1,2,8,9, Han Chan1,2,10, Takeshi Yoshida1,2,11, Marcelo B P Amato12, Niall D Ferguson2,4,13,4,14,15, Martin Post1,3,4, Brian P Kavanagh1,2,3,4,16,17, Laurent J Brochard2,18. 1. Translational Medicine Program, Hospital for Sick Children, Toronto, Ontario, Canada. 2. Interdepartmental Division of Critical Care Medicine. 3. The Institute of Medical Science. 4. Department of Physiology. 5. The Division of Pediatric Critical Care Medicine, Department of Pediatrics, Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Ontario, Canada. 6. School of Medicine and Surgery, University of Milan-Bicocca, Monza, Italy. 7. Departamento Ciencias de la Salud, Carrera de Kinesiología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile. 8. Department of Anesthesiology and. 9. Laboratory of Anesthesia and Intensive Care Medicine, West China Hospital of Sichuan University, Chengdu, Sichuan, China. 10. Surgical Intensive Care Unit, Fujian Provincial Hospital, Fuzhou, China. 11. The Department of Anesthesiology and Intensive Care Medicine, Osaka University Graduate School of Medicine, Suita, Japan. 12. Laboratório de Pneumologia LIM-09, Disciplina de Pneumologia, Instituto do Coração (Incor) Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil. 13. Department of Medicine. 14. Institute for Health Policy, Management, and Evaluation. 15. Division of Respirology, Department of Medicine, University Health Network and Sinai Health System, Toronto, Ontario, Canada. 16. Department of Critical Care Medicine, Hospital for Sick Children, and. 17. Toronto General Hospital Research Institute, Toronto, Ontario, Canada; and. 18. Department of Anesthesia, Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada.
Abstract
Rationale: The physiological basis of lung protection and the impact of positive end-expiratory pressure (PEEP) during pronation in acute respiratory distress syndrome are not fully elucidated. Objectives: To compare pleural pressure (Ppl) gradient, ventilation distribution, and regional compliance between dependent and nondependent lungs, and investigate the effect of PEEP during supination and pronation. Methods: We used a two-hit model of lung injury (saline lavage and high-volume ventilation) in 14 mechanically ventilated pigs and studied supine and prone positions. Global and regional lung mechanics including Ppl and distribution of ventilation (electrical impedance tomography) were analyzed across PEEP steps from 20 to 3 cm H2O. Two pigs underwent computed tomography scans: tidal recruitment and hyperinflation were calculated. Measurements and Main Results: Pronation improved oxygenation, increased Ppl, thus decreasing transpulmonary pressure for any PEEP, and reduced the dorsal-ventral pleural pressure gradient at PEEP < 10 cm H2O. The distribution of ventilation was homogenized between dependent and nondependent while prone and was less dependent on the PEEP level than while supine. The highest regional compliance was achieved at different PEEP levels in dependent and nondependent regions in supine position (15 and 8 cm H2O), but for similar values in prone position (13 and 12 cm H2O). Tidal recruitment was more evenly distributed (dependent and nondependent), hyperinflation lower, and lungs cephalocaudally longer in the prone position. Conclusions: In this lung injury model, pronation reduces the vertical pleural pressure gradient and homogenizes regional ventilation and compliance between the dependent and nondependent regions. Homogenization is much less dependent on the PEEP level in prone than in supine positon.
Rationale: The physiological basis of lung protection and the impact of positive end-expiratory pressure (PEEP) during pronation in acute respiratory distress syndrome are not fully elucidated. Objectives: To compare pleural pressure (Ppl) gradient, ventilation distribution, and regional compliance between dependent and nondependent lungs, and investigate the effect of PEEP during supination and pronation. Methods: We used a two-hit model of lung injury (saline lavage and high-volume ventilation) in 14 mechanically ventilated pigs and studied supine and prone positions. Global and regional lung mechanics including Ppl and distribution of ventilation (electrical impedance tomography) were analyzed across PEEP steps from 20 to 3 cm H2O. Two pigs underwent computed tomography scans: tidal recruitment and hyperinflation were calculated. Measurements and Main Results: Pronation improved oxygenation, increased Ppl, thus decreasing transpulmonary pressure for any PEEP, and reduced the dorsal-ventral pleural pressure gradient at PEEP < 10 cm H2O. The distribution of ventilation was homogenized between dependent and nondependent while prone and was less dependent on the PEEP level than while supine. The highest regional compliance was achieved at different PEEP levels in dependent and nondependent regions in supine position (15 and 8 cm H2O), but for similar values in prone position (13 and 12 cm H2O). Tidal recruitment was more evenly distributed (dependent and nondependent), hyperinflation lower, and lungs cephalocaudally longer in the prone position. Conclusions: In this lung injury model, pronation reduces the vertical pleural pressure gradient and homogenizes regional ventilation and compliance between the dependent and nondependent regions. Homogenization is much less dependent on the PEEP level in prone than in supine positon.
Authors: Laurent J Brochard; Martin Post; Bhushan H Katira; Doreen Engelberts; Sheena Bouch; Jordan Fliss; Luca Bastia; Kohei Osada; Kim A Connelly; Marcelo B P Amato; Niall D Ferguson; Wolfgang M Kuebler; Brian P Kavanagh Journal: Crit Care Date: 2022-02-18 Impact factor: 9.097
Authors: Christoph Boesing; Peter T Graf; Fabian Schmitt; Manfred Thiel; Paolo Pelosi; Patricia R M Rocco; Thomas Luecke; Joerg Krebs Journal: Crit Care Date: 2022-03-26 Impact factor: 9.097
Authors: David R Ziehr; Jehan Alladina; Molly E Wolf; Kelsey L Brait; Atul Malhotra; Carolyn La Vita; Lorenzo Berra; Kathryn A Hibbert; C Corey Hardin Journal: Crit Care Explor Date: 2021-06-15