Impact of Arterial CO Retention in Patients With Moderate or Severe ARDS.

BACKGROUND

Lung-protective ventilation (reduced tidal volume and limited plateau pressure) may lead to CO retention. Data about the impact of hypercapnia in patients with ARDS are scarce and conflicting.

METHODS

We performed a non-interventional cohort study with subjects with ARDS admitted from 2006 to 2021 and with P /F ≤ 150 mm Hg. We examined the association between severe hypercapnia (P ≥ 50 mm Hg) on the first 5 days after the diagnosis of ARDS and death in ICU for 930 subjects. All the subjects received lung-protective ventilation.

RESULTS

Severe hypercapnia was noted in 552 subjects (59%) on the first day of ARDS (day 1); 323/930 (34.7%) died in the ICU. Severe hypercapnia on day 1 was associated with mortality in the unadjusted (odds ratio 1.54, 95% CI 1.16-1.63; = .003) and adjusted (odds ratio 1.47, 95% CI 1.08-2.43; = .004) models. In the Bayesian analysis, the posterior probability that severe hypercapnia was associated with ICU death was > 90% in 4 different priors, including a septic prior for this association. Sustained severe hypercapnia on day 5, defined as severe hypercapnia present from day 1 to day 5, was noted in 93 subjects (12%). After propensity score matching, severe hypercapnia on day 5 remained associated with ICU mortality (odds ratio 1.73, 95% CI 1.02-2.97; = .047).

CONCLUSIONS

Severe hypercapnia was associated with mortality in subjects with ARDS who received lung-protective ventilation. Our results deserve further evaluation of the strategies and treatments that aim to control CO retention.