Acta Anaesthesiol Scand. 2020 Nov 9. doi: 10.1111/aas.13741. Online ahead of print.
BACKGROUND: The management of COVID-19 ARDS is debated. Although current evidence does not suggest an atypical ARDS, the physiological response to prone positioning is not fully understood and it is unclear which patients benefit. We aimed to determine whether proning increases oxygenation and to evaluate responders.
METHODS: This case series from a single, tertiary university hospital includes all mechanically ventilated patients with COVID-19 and proning between March 17, 2020 and May 19, 2020. The primary measure was change in PaO2 :FiO2 .
RESULTS: 44 patients, 32 males/12 females, were treated with proning for a total of 138 sessions, with median (range) 2 (1-8) sessions. Median (IQR) time for the five sessions was 14 (12-17) hours. In the first session, median (IQR) PaO2 :FiO2 increased from 104 (86-122) to 161 (127-207) mm Hg (p<0.001). 36 out of 44 patients (82%) improved in PaO2 :FiO2 , with a significant increase in PaO2 :FiO2 in the first three sessions. Median (IQR) FiO2 decreased from 0.7 (0.6-0.8) to 0.5 (0.35-0.6) (<0.001). A significant decrease occurred in the first three sessions. PaO2 , tidal volumes, PEEP, mean arterial pressure and norepinephrine infusion did not differ. Primarily, patients with PaO2 :FiO2 approximately <120 mm Hg before treatment responded to proning. Age, sex, BMI, or SAPS 3 did not predict success in increasing PaO2 :FiO2 .
CONCLUSION: Proning increased PaO2 :FiO2 , primarily in patients with PaO2 :FiO2 approximately < 120 mmHg, with a consistency over three sessions. No characteristic was associated with non-responding, why proning may be considered in most patients. Further study is required to evaluate mortality.