Initial end-tidal CO₂ partial pressure predicts outcomes of in-hospital cardiac arrest

Monitoring the partial pressure of end-tidal carbon dioxide (PEtco₂) has been advocated since 2010 as an index of resuscitation efforts. However, related research has largely focused on out-of-hospital cardiac arrest victims. In-hospital cardiac arrest (IHCA) differs in terms of etiologies and demographics, the merit of initial PEtco₂ values was explored.

This was a retrospective study in a single medical center between February 2011 and August 2014. Eligible subjects had suffered nontraumatic IHCA in the emergency department, where resuscitation was performed in accord with 2010 American Heart Association guidelines. Patients with initial PEtco₂ recordings via capnography were recruited.

A total of 353 IHCA events with initial PEtco₂ were recorded in 202 patients (male, 61.4%; mean age, 67.0 ± 16.2 years). Shockable rhythm (ventricular tachycardia/ventricular fibrillation) accounted for 11.8%. A cut point of 25.5 mm Hg was established for initial PEtco₂, creating 2 tiers of sustained return of spontaneous circulation (ROSC) that differed significantly in cumulative survival probability (log rank test, P = .002). For patients with initial PEtco₂ <25.5 mm Hg, survival benefit ceased at an earlier point in resuscitation, whereas above this threshold, the probability of survival cumulatively increased for a longer period. In multivariate analysis, initial PEtco₂ >25.5 mm Hg was found independently predictive of sustained ROSC (odds ratio, 2.64; 95% confidence interval, 1.43-4.88; P = .002), and survival to discharge (odds ratio, 3.10; 95% confidence interval, 1.26-7.60; P = .014), but failed to correlate with neurologic outcome.

In IHCA, the therapeutic threshold for initial PEtco₂ should set fairly higher to encourage more pulmonary flow and increase the likelihood of sustained ROSC.