Prognostic value of end-tidal carbon dioxide pressures during out-of-hospital cardiac arrest

Abstract

Study objective: To assess the prognostic value of initial end-tidal CO2 pressures (PETCO2) during CPR in patients with out-of-hospital cardiac arrest (OHCA).

Design: A prospective observational study using a convenience sample.

Setting: Primary service area of an advanced life support (ALS) ambulance service, including a city with a population of 70,745 and the surrounding area, with a population of 30,000.

Participants: Adults with nontraumatic OHCA.

Interventions: Quantitative monitoring of PETCO2 during CPR after endotracheal intubation using an infrared capnograph.

Results: PETCO2 after 1 and 2 minutes and the maximum PETCO2 during CPR were compared between the group in which restoration of spontaneous circulation (ROSC) was achieved and the group in which it was not. PETCO2 was measured during CPR in 27 patients. After 1 minute, PETCO2 was higher in patients who had on-scene ROSC than in patients without ROSC (23.0 +/- 7.4 versus 13.2 +/- 14.7 mm Hg, P = .0002). After 2 minutes, PETCO2 was higher in patients with ROSC (26.8 +/- 10.8 versus 15.4 +/- 5.7 mm Hg, P = .0019). The maximum PETCO2 during CPR was also higher in the ROSC group (30.8 +/- 9.5 versus 22.7 +/- 8.8 mm Hg, P = .0154). Thirteen of 27 patients presented in ventricular fibrillation (VF). The 1-minute (24.3 +/- 6.8 versus 12.0 +/- 4.2 mm Hg, P = .0022), 2-minute (28.2 +/- 11.4 versus 12.4 +/- 4.3 mm Hg, P = .0088), and maximum (33.0 +/- 10.2 versus 20.6 +/- 11.1 mm Hg, P = .0316) PETCO2 values during CPR were all significantly higher in patients in VF with ROSC.

Conclusion: In this observation study of 27 patients, initial PETCO2 during CPR with automated ventilation was prognostic for ROSC in patients with OHCA. Patients with ROSC have higher PETCO2 values after 1 and 2 minutes than do patients without ROSC.