End-tidal carbon dioxide levels predict cardiac arrest

Introduction

End-tidal carbon dioxide (CO₂) correlates with cardiac output during cardiopulmonary resuscitation (CPR) in cardiac arrest patients. Increasing CO₂ during CPR can also indicate the return of spontaneous circulation.

Methods

CO₂ was continuously monitored and recorded every 4 hours in 43 patients who were intubated and on vasopressor medications.

Results

Mean CO₂ values were significantly higher in normal patients when compared with those in patients who had a cardiac arrest (30.18 ± 4.93 vs. 17.45 ± 4.76; P < 0.001). CO₂ levels were significantly lower in cardiac arrest patients when compared with hypotensive patients 1, 2, 3, and 4 hours prior to a cardiac arrest (see Table 1). CO₂ levels were significantly lower in cardiac arrest patients when compared with patients who were acutely withdrawn from care 1, 2, 3, and 4 hours prior to the event (see Table 2).

Table 1 End-tidal CO₂ 5 hours prior to cardiac arrest compared with hypotension

Table 2 End-tidal CO₂ 5 hours prior to cardiac arrest versus acute withdrawal of care

Conclusions

CO₂ levels decrease prior to cardiac arrest and are signi-ficantly lower than prior to hypotensive or acute withdrawal of care events. Further study needs to be done on a larger scale to see whether these results hold true.