Computed tomography assessment of PEEP-induced alveolar recruitment in patients with severe COVID-19 pneumonia.

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.

• Authors: Lorenzo Ball, Chiara Robba, Lorenzo Maiello, Jacob Herrmann, Sarah E Gerard, Yi Xin, Denise Battaglini, Iole Brunetti, Giuseppe Minetti, Sara Seitun, Antonio Vena, Daniele Roberto Giacobbe, Matteo Bassetti, Patricia R M Rocco, Maurizio Cereda, Lucio Castellan, Nicolò Patroniti, Paolo Pelosi, GECOVID (GEnoa COVID-19) group
• Journal: Critical care (London, England) (Crit Care) Vol. 25 Issue 1 Pg. 81 (02 24 2021) ISSN: 1466-609X [Electronic] England
• PMID: 33627160 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Aged
• COVID-19 (complications, diagnostic imaging, epidemiology, physiopathology)
• Cohort Studies
• Female
• Humans
• Italy (epidemiology)
• Male
• Middle Aged
• Pneumonia, Viral (diagnostic imaging, therapy, virology)
• Positive-Pressure Respiration
• Pulmonary Alveoli (diagnostic imaging, physiology)
• Severity of Illness Index
• Tomography, X-Ray Computed
• Treatment Outcome