EFFECTS OF HALOTHANE, ISOFLURANE AND ENFLURANE ON VENTILATION IN CHILDREN

The ventilatory effects of halothane in eight children werecompared with those of isoflurane in eight children and enfluranein six children. All studies were completed before surgery commenced,and the children received no preopera-tive medication. The depressionof ventilation produced by the three agents increased in a dose-relatedfashion as the alveolar concentrations were increased, and thedepression of ventilation that they produced in oxygen was greaterthan that produced by equipotent concentrations in nitrous oxide.While the increase in ventilatory frequency and the decreasein T_E associated with increasing concentrations of halothanewere statistically significant (P < 0.05), the increase infrequency associated with isoflurane was not, although it wassufficient to maintain the end-tidal and arterial-ized venousPco, in the isoflurane group at a value which did not differsignificantly from that in the halothane group. Profound depressionof ventilation was produced in the children by enflurane, clearlybecause no increase in ventilatory frequency was associatedwith its use. It was evident that the ventilatory effects ofthe three volatile agents in unstimulated children are verysimilar to those described elsewhere in the adult. There wasno difference of any clinical significance between the degreeof depression of ventilation produced by halothane and isofluranein children.