Abstract 206: Distribution of ETCO 2 Values in Out-of-Hospital Cardiac Arrest Patients

Abstract

Background The American Heart Association 2010 guidelines recommend that capnography be used to verify tracheal tube placement and monitor CPR quality as well as detect ROSC during resuscitation. Capnography has been rapidly adopted by EMS in out-of-hospital CPR. Though capnography has been well understood in hospital patient care, the EtCO2 distribution in the population of interest has not been well studied. Objective Determine the distribution of EtCO2 levels during CPR in out-of-hospital cardiac arrest (OHCA) patients. Methods Recordings from 107 OHCA patients with capnogram waveforms were collected from 2008 to 2010 in two EMS agencies based in Oregon and Texas. Experts manually annotated all the recordings for breathing cycles and EtCO2 values. The histogram was generated using only the segments with active chest compression (total of 33 hours, 19,444 breath cycles). Each patient had chest compressions for an average of 19.8 ± 14.2 minutes. Chest compressions had an average rate of 108 ± 12 compressions-per-minute and average depth of 3.7 ± 0.7 centimeters. Results The figure below shows the distribution of the EtCO2 values in the OHCA patients. EtCO2 values varied from 0.5 to 99 mmHg, had a median value of 26 mmHg, and had an average value of 29 ± 18 mmHg. Conclusion In OHCA populations, EtCO2 values during CPR vary widely. EtCO2 values below 10 mmHg occurred in 13% of breaths and almost 60% of values were below 30 mmHg. Recommendations that make use of EtCO2 values in OHCA should consider this distribution.