Does metabolic recovery predict time to extubation after cardiac surgery?

Introduction: Carbon dioxide production (VCO2), and oxygen consumption (VO2), measures of metabolic recovery, are significant determinants of outcome after CPB. The purpose of this study was to determine whether body temp (TB) is a surrogate of metabolic recovery and time to extubation (IntubT) after CPB. Methods: Following IRB approval, we enrolled 27 patients undergoing elective cardiac procedures under hypothermic CPB. Selection criteria included EF≥45% and absence of significant organ dysfunction. Moderate whole body hypothermia was achieved to a range of 28-32°C. TB was recorded via PA cath, while VCO2 was measured with the CO2SMO Plus monitor (Novametrix Inc., Wallingford, CT). Simultaneous arterial and venous blood gases and hemodynamic measures were collected from anesthetized patients, under constant mechanical ventilation, and with the chest closed. VO2 was calculated using Fick's principle. Measurement times were pre-CPB, then at 1, 2, 4 and 6 hours post-CPB. Statistical analyses included correlation Z-test (95% Cl; p<0.05 accepted as significant) and simple linear regression of IntubT vs. TB. (Figure Presented) Results: Longer IntubT was associated with lower TB (Fig 1). VCO2 and TB showed parallel increases with time after CPB (Fig 2). TB was positively correlated to VCO2 and VO2. Age was negatively correlated to TB, VO2 and VCO2. Of all CPB factors examined (duration, cardioplegia volume, and cooling temp), TB correlated positively to cooling temp and BSA. (Figure Presented) Conclusion: TB and associated VO2 and VCO2 changes may be predictive of postoperative intubation time following open heart surgery, and warrant further study of rewarming techniques especially with regard to metabolic recovery in the elderly.

Duke Scholars

Author Loreta Grecu Anesthesiology, Cardiothoracic