Lorenzo Ball1,2, Chiara Robba3, Lorenzo Maiello4, Jacob Herrmann5, Sarah E Gerard6, Yi Xin7, Denise Battaglini3, Iole Brunetti3, Giuseppe Minetti8, Sara Seitun8, Antonio Vena9, Daniele Roberto Giacobbe9, Matteo Bassetti9,10, Patricia R M Rocco11, Maurizio Cereda12, Lucio Castellan8, Nicolò Patroniti4,3, Paolo Pelosi4,3. 1. Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa, Viale Benedetto XV 16, Genoa, Italy. lorenzo.ball@unige.it. 2. Anesthesia and Intensive Care, Ospedale Policlinico San Martino, IRCCS Per L'Oncologia e le Neuroscienze, Genoa, Italy. lorenzo.ball@unige.it. 3. Anesthesia and Intensive Care, Ospedale Policlinico San Martino, IRCCS Per L'Oncologia e le Neuroscienze, Genoa, Italy. 4. Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa, Viale Benedetto XV 16, Genoa, Italy. 5. Department of Biomedical Engineering, Harvard Medical School, Boston, MA, USA. 6. Department of Radiology, Harvard Medical School, Boston, MA, USA. 7. Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. 8. Radiology Department, Ospedale Policlinico San Martino, IRCCS Per L'Oncologia e le Neuroscienze, Genoa, Italy. 9. Infectious Diseases Unit, Ospedale Policlinico San Martino, IRCCS Per L'Oncologia e le Neuroscienze, Genoa, Italy. 10. Department of Health Sciences (DISSAL), University of Genoa, Genoa, Italy. 11. Laboratory of Pulmonary Investigation, Carlos Chagas Filho Institute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil. 12. Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Abstract
BACKGROUND: There is a paucity of data concerning the optimal ventilator management in patients with COVID-19 pneumonia; particularly, the optimal levels of positive-end expiratory pressure (PEEP) are unknown. We aimed to investigate the effects of two levels of PEEP on alveolar recruitment in critically ill patients with severe COVID-19 pneumonia. METHODS: A single-center cohort study was conducted in a 39-bed intensive care unit at a university-affiliated hospital in Genoa, Italy. Chest computed tomography (CT) was performed to quantify aeration at 8 and 16 cmH2O PEEP. The primary endpoint was the amount of alveolar recruitment, defined as the change in the non-aerated compartment at the two PEEP levels on CT scan. RESULTS: Forty-two patients were included in this analysis. Alveolar recruitment was median [interquartile range] 2.7 [0.7-4.5] % of lung weight and was not associated with excess lung weight, PaO2/FiO2 ratio, respiratory system compliance, inflammatory and thrombophilia markers. Patients in the upper quartile of recruitment (recruiters), compared to non-recruiters, had comparable clinical characteristics, lung weight and gas volume. Alveolar recruitment was not different in patients with lower versus higher respiratory system compliance. In a subgroup of 20 patients with available gas exchange data, increasing PEEP decreased respiratory system compliance (median difference, MD - 9 ml/cmH2O, 95% CI from - 12 to - 6 ml/cmH2O, p < 0.001) and the ventilatory ratio (MD - 0.1, 95% CI from - 0.3 to - 0.1, p = 0.003), increased PaO2 with FiO2 = 0.5 (MD 24 mmHg, 95% CI from 12 to 51 mmHg, p < 0.001), but did not change PaO2 with FiO2 = 1.0 (MD 7 mmHg, 95% CI from - 12 to 49 mmHg, p = 0.313). Moreover, alveolar recruitment was not correlated with improvement of oxygenation or venous admixture. CONCLUSIONS: In patients with severe COVID-19 pneumonia, higher PEEP resulted in limited alveolar recruitment. These findings suggest limiting PEEP strictly to the values necessary to maintain oxygenation, thus avoiding the use of higher PEEP levels.
BACKGROUND: There is a paucity of data concerning the optimal ventilator management in patients with COVID-19 pneumonia; particularly, the optimal levels of positive-end expiratory pressure (PEEP) are unknown. We aimed to investigate the effects of two levels of PEEP on alveolar recruitment in critically illpatients with severe COVID-19 pneumonia. METHODS: A single-center cohort study was conducted in a 39-bed intensive care unit at a university-affiliated hospital in Genoa, Italy. Chest computed tomography (CT) was performed to quantify aeration at 8 and 16 cmH2O PEEP. The primary endpoint was the amount of alveolar recruitment, defined as the change in the non-aerated compartment at the two PEEP levels on CT scan. RESULTS: Forty-two patients were included in this analysis. Alveolar recruitment was median [interquartile range] 2.7 [0.7-4.5] % of lung weight and was not associated with excess lung weight, PaO2/FiO2 ratio, respiratory system compliance, inflammatory and thrombophilia markers. Patients in the upper quartile of recruitment (recruiters), compared to non-recruiters, had comparable clinical characteristics, lung weight and gas volume. Alveolar recruitment was not different in patients with lower versus higher respiratory system compliance. In a subgroup of 20 patients with available gas exchange data, increasing PEEP decreased respiratory system compliance (median difference, MD - 9 ml/cmH2O, 95% CI from - 12 to - 6 ml/cmH2O, p < 0.001) and the ventilatory ratio (MD - 0.1, 95% CI from - 0.3 to - 0.1, p = 0.003), increased PaO2 with FiO2 = 0.5 (MD 24 mmHg, 95% CI from 12 to 51 mmHg, p < 0.001), but did not change PaO2 with FiO2 = 1.0 (MD 7 mmHg, 95% CI from - 12 to 49 mmHg, p = 0.313). Moreover, alveolar recruitment was not correlated with improvement of oxygenation or venous admixture. CONCLUSIONS: In patients with severe COVID-19 pneumonia, higher PEEP resulted in limited alveolar recruitment. These findings suggest limiting PEEP strictly to the values necessary to maintain oxygenation, thus avoiding the use of higher PEEP levels.
Entities:
Keywords:
ARDS; COVID-19; CT scan; Mechanical ventilation; Respiratory system mechanics
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