Cimetidine in the prevention of acid aspiration during anesthesia.

In a controlled, randomized, double-blind trial, the value of cimetidine as prophylaxis against acid aspiration pneumonitis was studied. Compared to placebo, cimetidine reduced the volume as well as the acidity of the gastric contents significantly. The patients at risk of developing severe pneumonitis after aspiration (pH less than 2.5 and volume greater than 20 ml) were reduced from 55% in the placebo group to 0 in the group having received cimetidine 400 mg the night before and a further 400 mg on the morning of surgery. Premedication with cimetidine may be useful if rapid intubation cannot be anticipated.