Cardiac rhythm and left ventricular function of infants at 1 MAC sevoflurane and halothane

The implementation of sevoflurane in pediatric anesthesia practice led to a decrease in the incidence of cardiac arrest previously reported with halothane. Nevertheless, the effects of sevoflurane on cardiac rhythm and function have not been systematically investigated in infants. Thus, we compared cardiac rhythm and left ventricular function at 1 MAC sevoflurane and halothane anesthesia and investigated the potential benefit effect of atropine.

Twenty infants ASA physical status I or II were randomly assigned to have anesthesia induced with either sevoflurane (up to 5%) or halothane (up to 1.5%). After insertion of an i.v. line, anesthesia was maintained at 1 MAC sevoflurane (group S) or 1 MAC halothane (group H) with infants breathing spontaneously in 100% oxygen. Cardiac output and contractility were measured by transthoracic echocardiography. Three sets of hemodynamic parameters were averaged prior to and after administration of 20 microg x kg(-1) of i.v. atropine.

Infants breathing spontaneously 1 MAC halothane or 1 MAC sevoflurane were found to have comparable hemodynamic parameters. After atropine administration, heart rate and cardiac index (CI) increased significantly in both groups (19.6 +/- 7.6% in group H and 21.3 +/- 13.1% in group S, 18.6 +/- 8.8% in group H and 17.7 +/- 12% in group S respectively). Moreover, atropine induced an increase in left ventricular shortening fraction with no difference between groups. In contrast, only infants in group S presented a significant increase in ejection fraction.

Indices of left ventricular function were comparable between groups with no clinically significant change following atropine administration. The present study confirms the favorable hemodynamic profile of sevoflurane in infants breathing spontaneously at 1 MAC concentration.