Moderate-to-severe ARDS: COVID-19 patients compared to influenza patients for ventilator parameters and mortality.

BACKGROUND

This study aimed to compare ventilatory parameters recorded in the first days of acute respiratory distress syndrome (ARDS) and mortality at day 60 between coronavirus disease 2019 (COVID-19) and influenza ARDS patients with arterial oxygen tension ( )/inspiratory oxygen fraction ( ) ≤150 mmHg.

METHODS

We compared 244 COVID-19 ARDS patients with 106 influenza ARDS patients. Driving pressure, respiratory system compliance ( ), ventilator ratio, corrected minute ventilation (') and surrogate of mechanical power (index=(4×driving pressure)+respiratory rate) were calculated from day 1 to day 5 of ARDS. A propensity score analysis and a principal component analysis (PCA) were performed.

RESULTS

On day 1 of ARDS, COVID-19 patients had significantly higher / (median (interquartile range) 97 (79-129.2) 83 (62.2-114) mmHg; p=0.001), and lower driving pressure (13.0 (11.0-16.0) 14.0 (12.0-16.7) cmHO; p=0.01), ventilatory ratio (2.08 (1.73-2.49 2.52 (1.97-3.03); p<0.001), ' (12.7 (10.2-14.9) 14.9 (11.6-18.6) L·min; p<0.001) and index (80 (70-89) 84 (75-94); p=0.004). PCA demonstrated an important overlap of ventilatory parameters recorded on day 1 between the two groups. From day 1 to day 5, repeated values of / , arterial carbon dioxide tension, ventilatory ratio and ' differed significantly between influenza and COVID-19 patients in the unmatched and matched populations. Mortality at day 60 did not differ significantly after matching (29% 21.7%; p=0.43).

CONCLUSIONS

Ventilation was more impaired in influenza than in COVID-19 ARDS patients on the first day of ARDS with an important overlap of values. However, mortality at day 60 did not differ significantly in the matched population.