END-TIDAL CO2 LEVELS ARE A RELIABLE INDICATOR OF BAND TIGHTNESS IN PULMONARY-ARTERY BANDING

Background. Monitoring of end-tidal CO2 levels, performed routinely no wadays in most operating rooms, is obligatory in our hospital for all anesthesia patients. Levels are dependent on pulmonary blood now, vent ilation, and CO2 content of blood. When ventilation is kept constant, the end-tidal CO2 closely follows pulmonary blood now. Methods. Reduct ion of end-tidal CO2 in the expired air was used to adjust tightness o f the pulmonary band in 10 patients with complex cardiac anomalies, al l including ventricular septal defect, who underwent pulmonary artery banding. Other parameters were systemic blood pressures and distal pul monary artery pressures. Results. There were no operative deaths. Aver age reduction was 3.8 mm Hg (range, 2 to 10 mm Hg; p < 0.001 by paired t test), average increase in systolic blood pressure was 14 mm Hg (ra nge, 4 to 20 mm Hg; p < 0.03 by Wilcoxon sign rank test), distal pulmo nary artery pressure was reduced from 56 mm Hg (range, 37 to 79 mm Hg) to 29 mm Hg (range, 20 to 38 mm Hg; p < 0.03 by t test), and postoper ative pulmonary artery to systemic pressure ratio averaged 0.36 mm Hg (range, 0.24 to 0.49 mm Hg, difference from preoperative value, p < 0. 06). Conclusions. End-tidal CO2 tension is a simple and convenient, ye t highly reliable parameter for adjusting pulmonary artery band tightn ess.