Body positioning may affect lung recruitability in COVID-19-related ARDS
Alternating between supine and prone positioning appeared to improve lung recruitability in a small cohort of mechanically ventilated patients with severe COVID-19 infection who developed acute respiratory distress syndrome in Wuhan, China, according to a research letter published in the American Journal of Respiratory and Critical Care Medicine.
“This study is the first description of the behavior of the lungs in patients with severe COVID-19 requiring mechanical ventilation and receiving positive pressure,” Haibo Qiu, MD, professor in the department of critical care medicine at Zhangda Hospital, School of Medicine, Southeast University in Nanjing, China, said in a press release. “It indicates that some patients do not respond well to high positive pressure and respond better to prone positioning in bed (facing downward).”
The retrospective observational cohort study, which was conducted by Qiu and colleagues at the Wuhan Jinyintan Hospital in China, included 12 patients — seven men and five women (mean age, 59 years) — with ARDS related to COVID-19 infection who were transferred from other treatment centers. All patients received invasive mechanical ventilation, were under continuous infusion of sedatives and were assessed for respiratory mechanics. This included lung recruitability, which was gauged using a previously developed index — the recruitment-to-inflation ratio (R/I) — that measures the response of lungs to pressure.
During the 6-day study that took place during the week of Feb. 18, the researchers evaluated the effect of body positioning on these patients. Notably, prone positioning was performed in 24-hour periods in which patients had persistently low levels of blood oxygenation.
At intubation, the ratio of partial pressure arterial oxygen and fraction of inspired oxygen (PaO2/FiO2) was 130 mm Hg with a partial pressure of carbon dioxide of 57 mm Hg. The researchers noted that patients had received various days of noninvasive or invasive ventilatory support before the first day of observation. During the study, seven patients received at least one session of prone positioning, three received both prone positioning and extracorporeal membrane oxygenation and three died.
On the first day of observation, 10 patients were poorly recruitable, with an R/I of 0.21. Among patients who did not receive prone positioning, poor recruitability persisted, with only one of 17 daily measurements showing high recruitability, according to the data. Alternating body position between supine and prone positioning, however, was linked to increased lung recruitability, with 13 of 36 daily measurements showing high recruitability (P = .02). Additionally, PaO2/FiO2 increased from 120 mm Hg to 182 mm Hg at prone position (P = .065).
“It is only a small number of patients, but our study shows that many patients did not reopen their lungs under high positive pressure and may be exposed to more harm than benefit in trying to increase the pressure,” Chun Pan, MD, professor at Zhongda Hospital, School of Medicine, Southeast University, said in the release. “By contrast, the lung improves when the patient is in the prone position. Considering this can be done, it is important for the management of patients with severe COVID-19 requiring mechanical ventilation.”
In the research letter, Qiu, Pan and colleagues noted that the findings do not indicate that all patients with COVID-19-related ARDS were poorly recruitable and that severity and management of patients can differ among regions.
“Instead, we think these findings might incite clinicians to assess respiratory mechanics and lung recruitability in this population,” they wrote. – by Melissa Foster
Disclosure: This study was partly supported by a research grant from the Ministry of Science and Technology of the People’s Republic of China.