Background and objective: Children are vulnerable to regurgitation with a relatively high incidence of aspiration during general anaesthesia which is attributed to the high intragastric pressure, a short oesophagus, an immature laryngeal reflex and incomplete lower oesophageal sphincter muscle function. Subcutaneous administration of epinephrine is generally used in surgery to decrease bleeding due to local vasoconstriction. The effect of epinephrine on the sphincter muscle tone was investigated during general anaesthesia in children.

Methods: Ten children scheduled for skin graft or plastic surgery of the ear were studied. A gastrointestinal pressure sensor was inserted nasally, and the intraluminal pressures of the lower oesophagus, lower oesophageal sphincter and stomach were monitored under sevoflurane, nitrous oxide anaesthesia. The effect of epinephrine on the lower oesophageal sphincter muscle tone was measured.

Results: The resting pressure of the lower oesophageal sphincter muscle tone significantly decreased from 4.56 ± 1.85 to 3.79 ± 1.11 kPa after 3 μg kg−1 epinephrine for 4 min. The barrier pressure is the difference between the lower oesophageal sphincter and intragastric pressure, and that decreased to 1.23 ± 1.17 kPa from the 2.07 ± 1.77 kPa resting level. The observations implied that epinephrine had a long-lasting relaxing effect on lower oesophageal sphincter muscle in children.

Conclusions: The observations may give some explanation about the mechanism of gastro-oesophageal reflux during general anaesthesia, especially in the participation of the adrenergic receptors.