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Middle ear pressure variations during nitrous oxide and oxygen anaesthesia
Canadian Anaesthetists' Society Journal
|September 1, 1982
Summary
Nitrous oxide anesthesia can cause middle ear pressure changes. Blocked Eustachian tubes during recovery may lead to unnoticed tympanic perforations or haemotympanum.
Area of Science:
- Anesthesiology
- Otolaryngology
- Medical Physiology
Background:
- Middle ear pressure variations during nitrous oxide inhalation are documented.
- Eustachian tube patency significantly influences these pressure changes.
Purpose of the Study:
- To characterize middle ear pressure variations during anesthesia with nitrous oxide and oxygen, supplemented with halogens or narcotics.
- To correlate pressure changes with Eustachian tube patency.
- To identify potential complications such as tympanic perforation.
Main Methods:
- Monitored middle ear pressure in anesthetized subjects (excluding ear operations).
- Administered nitrous oxide and oxygen, supplemented with halogens or narcotics.
- Categorized pressure changes based on Eustachian tube patency.
Main Results:
- Identified three distinct middle ear pressure curves related to Eustachian tube patency.
- Observed significant negative middle ear pressures during recovery with Eustachian tube obstruction.
- Reported one case of tympanic perforation and one case of haemotympanum.
Conclusions:
- Eustachian tube obstruction during nitrous oxide anesthesia recovery can cause significant negative middle ear pressure.
- A tympanic 'neomembrane' with Eustachian tube obstruction may mask unnoticed tympanic perforations.
- Anesthetists must specifically investigate potential ear complications.