Comparing the effects of desflurane and isoflurane on middle ear pressure.

The aim of this study was to determine middle ear pressure changes during the operation performed under anaesthesia induced by isoflurane or desflurane. This was a prospective, case-control study. A total of 38 children with no middle ear pathology scheduled for inguinal hernia surgery were included in the study. Group I (n = 22) received isoflurane and Group II (n = 16) received desflurane. Baseline tympanometry was performed before the anaesthesia on both ears, and tympanometry was repeated 5, 10 and 15 minutes after the administration and 10 and 30 minutes after the withdrawal of anaesthetic agents. Data were analyzed using the Mann-Whitney U (inter-group) and the Wilcoxon test (intra-group) procedures. The mean middle ear pressure values in the 44 ears of the 22 children in Group I and the 32 ears of the 16 children in Group II did not show any significant difference before the anaesthesia by either anaesthetic agent (p > 0.05). Increase in the mean middle ear pressure values at the 5(th) and 10(th) minute of the operation was significant different between both groups (2.84 and 5.80 daPa for isoflurane; 59.06 and 72.81 daPa for desflurane; p ≤ 0.05). Desflurane is more increased than isoflurane on intra-tympanic pressure and isoflurane may be used more safely than desflurane in middle ear operations. The low effect of isoflurane on intra-tympanic pressure can be explained by the high blood/gas partition coefficient compared to desflurane.