Association between end tidal capnography dynamics following vasopressor administration.
Resuscitation plus · 2026-03-20 · Observational study
Abstract
BACKGROUND: Dynamic changes in end-tidal CO2 (EtCO2) may reflect changes in perfusion and ventilation during cardiopulmonary resuscitation. However, EtCO2 dynamics following vasopressor administration in out-of-hospital cardiac arrest (OHCA) is unknown. We sought to characterize EtCO2 variations after single dose vasopressor administration. METHOD: We performed a secondary analysis from the Pragmatic Airway Resuscitation Trial. We summarized maximal EtCO2 values into one-minute epochs using previously validated automated signal processing. We identified vasopressor administration times using patient records and defibrillator timestamps. We studied changes in EtCO2 morphology after vasopressor administration, including time (minutes) to 15% rise above baseline, time to peak EtCO2, peak proportional change in EtCO2, and duration of EtCO2 over 15%. We compared differences in EtCO2 morphology between return-of-spontaneous circulation (ROSC) and non-ROSC using Mann-Whitney U tests. RESULTS: We included 517 patients with EtCO2 recorded during a single dose of vasopressor. 139 patients (27%) achieved ROSC. Lag time (ROSC: 1.87 min, IQR 0.88-3.38 vs. non-ROSC: 1.93 min, IQR 0.77-3.50; p = 0.177) and peak time (ROSC: 3.43 min, IQR 1.44-6.67 vs. non-ROSC: 2.70 min, IQR 1.10-4.99; p = 0.129) were not associated with ROSC. Proportional change in EtCO2 (ROSC: 43.33%, IQR 15.01-105.88 vs. non-ROSC: 24.67%, IQR 4.86-64.10; p < 0.001) and rise duration (ROSC: 4.00 min, IQR 0.50-10.00 vs. non-ROSC: 1.00 min, IQR 0.50-5.75; p < 0.001) were associated with ROSC. CONCLUSION: Following a single dose of vasopressor, EtCO2 increased and remained elevated for longer durations in ROSC patients. EtCO2 changes after vasopressor administration may reflect progression of OHCA resuscitation.