The effect of general anaesthesia and neuromuscular blockade on Eustachian tube compliance: a prospective study.

OBJECTIVE: The most common complications of hyperbaric oxygen treatment (HBOT) are related to pressure changes on gas-containing cavities. Therefore, inability to auto-inflate the middle ear may result in transient or permanent hearing loss. However, it seems that middle ear barotrauma (MEBt) does not develop more often in mechanically ventilated patients than in ambulatory patients. This might be explained by deep sedation of these patients. Therefore, the aim of this study was to determine whether anaesthesia and/or neuromuscular blockade can influence Eustachian tube (ET) function.

METHODS: Forty patients who were undergoing surgery under general anaesthesia were enrolled in this prospective study. ET function was evaluated by tympanography performed three times: before induction of general anaesthesia (baseline), after induction with sufentanyl/propofol and after full blockade was achieved with a long-acting neuromuscular blocking agent.

RESULTS: There were no differences in ear volume (P = 0.19) and ear pressure (P = 0.07). There was a significant variation in compliance on tympanography after the induction of general anaesthesia (P = 0.009). Compared to the baseline, this variation was characterized by an increase after induction of anaesthesia (24 ± 7.13%, P 〈 0.01) and neuromuscular blockade (23 ± 8.9%, P 〈 0.05). The difference between after induction and after neuromuscular blockade was not statistically significant (P = 0.13).

DISCUSSION: The findings of this trial suggest that the administration of hypnotic drugs associated with opioids improves ET compliance. Therefore it may have favourable prophylactic effects on MEBt in ventilated intensive care unit patients scheduled for HBOT.