Patients with hypoxemic acute respiratory failure as a result of coronavirus disease 2019 (COVID-19) who received continuous positive airway pressure (CPAP) therapy had a high failure rate during prone/lateral positioning tests, according study results published in CHEST.
Patients with COVID-19 at the high dependency unit of a hospital in Milan, Italy who were spontaneously breathing and not intubated but undergoing helmet CPAP treatment were assessed for lung function and blood oxygenation after a number of positioning tests. Patients who had monolateral lung impairment were placed laterally, while patients with bilateral impairment were placed prone. Alveolar-arterial gradient (A-aO2) was recorded at 3 time points: at baseline in a semi-seated position, after 1 hour with the patient in prone/lateral position, and 45 minutes with the patient returned to a semi-seated position. A decrease of ≥20% from baseline was considered clinically significant.
Of the 26 patients with COVID-19, the mean age was 62 years and 67% were men. Systemic hypertension, diabetes, obesity, COPD, and asthma were common comorbidities. A total of 39 tests consisting of 12 prone and 27 lateral positioning were conducted. For the primary study end point, 15.4% of positioning trials were successful with a decrease of A-aO2 of ≥20% in comparison to baseline, 7.7% showed a A-aO2 decrease of ≥30% in comparison with baseline, 46.1% trials showed a decrease of <20% of A-aO2 compared with baseline, and a total of 38.5% trials failed.
The researchers noted that “[t]he relatively high failure rate might be mainly related to the complex pathophysiology of respiratory failure in COVID-19 patients, where diffuse alveolar damage (like in ‘classical’ ARDS) and diffuse endothelial damage leading to pulmonary intravascular coagulopathy with disseminated micro-thrombosis were found.”
There were several study limitations, including the design, which was “purely physiologic,” meaning that researchers did not assess the potential effect of prone/lateral positioning on clinical outcomes or confounders (eg, ventilator setting) and the length of CPAP treatment before the trial. In addition, the response and tolerance of the patients were evaluated only after 1 hour from test initiation.
Nonetheless, these findings could help design future randomized controlled trials on prone/later positioning in patients with COVID-19 who are not intubated.
Retucci M, Aliberti S, Ceruti C, et al. Prone and lateral positioning in spontaneously breathing patients with COVID-19 pneumonia undergoing noninvasive helmet CPAP treatment [published online July 14, 2020]. CHEST. doi:10.1016/j.chest.2020.07.006