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Upper oesophageal sphincter pressure during inhalational anaesthesia
R G Vanner1, B J Pryle, J P O'Dwyer
1Department of Anaesthetics, St Thomas' Hospital, London.
Anaesthesia
|November 1, 1992
Summary
Halothane anesthesia maintained upper esophageal sphincter tone, unlike thiopental or suxamethonium. However, some patients remained at risk for regurgitation due to low sphincter pressure.
Area of Science:
- Anesthesiology
- Gastroenterology
Background:
- The upper esophageal sphincter (UES) plays a crucial role in preventing oropharyngeal aspiration and gastroesophageal reflux.
- Understanding how anesthetic agents affect UES pressure is vital for patient safety during procedures.
Purpose of the Study:
- To investigate the effects of different anesthetic agents and techniques on upper esophageal sphincter (UES) pressure.
- To compare the impact of inhalational anesthesia (halothane) versus intravenous agents (thiopentone, suxamethonium) on UES tone.
Main Methods:
- Upper esophageal sphincter pressure was measured using a Dent sleeve in 30 patients undergoing anesthesia.
- Patients were divided into groups receiving thiopentone/suxamethonium with or without prior inhalational anesthesia, or solely inhalational induction.
- Halothane concentration and laryngeal mask insertion effects were assessed.
Main Results:
- Inhalational induction with halothane (Group C) resulted in higher mean UES pressure (24 mmHg) compared to thiopentone/suxamethonium groups (8-6 mmHg).
- At 1.5% end-tidal halothane, UES pressure was significantly lower in patients receiving it after thiopentone/suxamethonium (Group B, 16 mmHg) than those with inhalational induction (Group C, 27 mmHg) or intubation before anesthesia (Group A, 45 mmHg).
- Halothane did not show a dose-dependent effect, and laryngeal mask insertion had no significant impact on UES pressure.
Conclusions:
- Halothane anesthesia, particularly with inhalational induction, helps maintain upper esophageal sphincter tone.
- Despite this, some patients exhibited low UES pressures (<10 mmHg), indicating a potential risk for regurgitation and aspiration, especially with concurrent gastroesophageal reflux.