The effect of hyoscine and atropine on the lower oesophageal sphincter.

The effects of intravenous hyoscine 0-4 mg and atropine 0-6 mg on lower oesophageal sphincter tone were studied in normal human subjects. Hyoscine and atropine both decreased the lower oesophageal sphincter (L.O.S) pressure by approximately 11 cm H2O (p less than 0-01). There was also an increased incidence of reflux as seen by an indwelling pH electrode in the lower oesophagus. These findings are relevant to the preoperative preparation of patients presenting for emergency obstetrical anaesthesia; since gastro-oesophagus reflux and pulmonary aspiration of acid gastric content continues to be a significant cause of morbidity and mortality.