Correlation of end tidal carbon dioxide with arterial carbon dioxide during cardiopulmonary bypass

Optimal blood gas management is subjected to pH- and alpha- state during hypothermia; Alpha state managed by maintaining constant total carbon dioxide stores during cardiopulmonary bypass (CPB) changes thermodynamic dissociation with change in temperature. pHremains constant during temperature changes. A correlation between end tidal carbon dioxide and arterial PCO2 known to be a non- invasive and safe procedure in patients undergoing Coronary artery bypass graft.

Forty patients were maintained with normothermia and hypothermia during cardiac surgery in the current study. All patients were operated with midline sternotomy, aortic bicavalcannulation or aortic-right atrium cannulation for cardiopulmonary bypass. Arterial Blood Gas measurements (ABG) along with ETCO2 and PaCO2 monitoring were performed.

The patient group had undergone a variety of surgical procedures (viz. Coronary artery bypass grafting, Replacement of mitral- or aortic- valve or double valve). They were maintained on CPB with aorta cross clamp. There was no significant difference in ETCO2 and PaCO2 pressures both at normothermia as well as moderate hypothermia during CPB.

Monitoring ETCO2 reflects accurate measurements of PaCO2. Repeated sampling for ABG therefore can be avoided as a cheap, non-invasive method to ascertain the health of the patients.