End Tidal CO2 Derived Variable as a Prognostic Factor in Post Resuscitated Cardiac Arrest Patients

Kim, Jong Kyu; Lee, Sung Woo; Yang, Jia; Kim, Su Jin; Choi, Sung Hyuk; Hong, Yun Sik

Abstract

PURPOSE: End-tidal carbon dioxide (ETCO2) reflects pulmonary perfusion and ventilation of resuscitated cardiac arrest patients. Single use of ETCO2 has some limitations in predicting outcomes of cardiac arrest. We hypothesized the dead space ventilation ratio (Vdt/Vt) using arterial CO2 and ETCO2 difference (Pa-etCO2) can be used as a better prognostic indicator of survival in resuscitated cardiac arrest patients.
METHODS
94 patients were cardiac arrest in emergency department from January 2004 to october 2005. Patients were intubated in the emergency department and treated using the standard advanced cardiac life support protocol. 48 patients were resuscitated following cardiac arrest. Their ETCO2 were evaluated by using mainstream capnography. ETCO2 and simultaneously, blood gas studies were evaluated within 1 hour following return of spontaneous circulation (ROSC). 17 Patients were excluded because they had chronic pulmonary disease or they were cardiac arrest after cerebrovascular accident.
RESULTS
There was no difference in mean age, arrest rhythm, systolic blood pressure, and base excess between patients that were discharged alive and patients that died in the hospital. Arterial pH of patients expired within 24 hours was significantly lower than that of survivors. The ETCO2 following ROSC averaged 19.7 +/- 10.73 mmHg in cases of hospital death with ROSC< 24 hours, 31.4 +/- 14.04 mmHg in cases of hospital death with ROSC> 24 hours and 26.2 +/- 5.22 mmHg in survivors (p=0.050). The VdA/Vt averaged 0.20 +/- 0.087 mmHg in alive discharges, 0.59 +/- 0.187 mmHg in hospital death with ROSC<24 hours and 0.36 +/- 0.176 mmHg in hospital deaths with ROSC> 24 hours (p=0.000).
CONCLUSION
This study showed that high P(a-et)CO2 and high VdA/Vt suggest poor outcomes in arrest patients with ROSC. If future studies validate this model, the use of VdA/Vt that compare to ETCO2 may be a more useful adjunct in assessing the outcomes of cardiac arrest..