Written by Rebecca White
Spoon Feed
In patients resuscitated after out-of-hospital cardiac arrest (OHCA), targeted mild hypercapnia was not associated with better neurologic outcomes at 6 months compared to normocapnia.
More CO2 may not be better…
Normocapnia has been the standard after OHCA; however, mild hypercapnia increases cerebral blood flow – could this improve neurologic outcomes?
In this randomized controlled trial, 1,700 patients with coma post-OHCA from 63 ICUs in 17 countries were included, with 847 patients assigned to 24 hours of mild hypercapnia (PaCO2 50 to 55mmHg) and 853 to normocapnia (PaCO2 35 to 45mmHg). Favorable neurologic outcome at 6 months occurred in 43.5% of mild hypercapnia group (332 of 764) and in 44.6% of normocapnia group (350/784; relative risk 0.98 (95%CI 0.87-1.11; P = 0.76). Death within 6 months after randomization occurred in 48.2% of mild hypercapnia group (393/816) and in 45.9% of the normocapnia group (382/832; relative risk 1.05 (95%CI 0.94-1.16). There was no significant difference in adverse events between groups.
This study is well-executed and well-powered, though is not fully blinded. Hypercapnia was common at randomization, and this may have muddied the waters between groups. Additionally, generalizability is limited, as this study did not examine in-hospital cardiac arrest, and most patients had witnessed arrests with shockable rhythms and bystander resuscitation.
How will this change my practice?
For now, we will continue to strive for normocapnia in post-OHCA patients.
Source
Mild Hypercapnia or Normocapnia after Out-of-Hospital Cardiac Arrest. N Engl J Med. 2023 Jun 15. doi: 10.1056/NEJMoa2214552. Epub ahead of print.
