Ranitidine and Metoclopramide for Prophylaxis of Aspiration Pneumonitis in Elective Surgery

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Abstract
The effects of preanesthetic oral ranitidine and metoclopramide on gastric contents were studied in 150 inpatients scheduled for elective surgery with random allocation into ten groups with fifteen patients in each group. Patients in group I served as controls. Group II patients received metoclopramide, 10 mg, in the morning. Patients in group III received ranitidine, 150 mg; while group IV patients received ranitidine, 150 mg, and metoclopramide, 10 mg, also in the morning. Group V patients received ranitidine, 150 mg, at bedtime and in the morning; while patients in group VI received ranitidine as in group V and, in addition, received metoclopramide, 10 mg, in the morning. Group VII patients received ranitidine, 300 mg, in the morning; while patients in group VIII received ranitidine, 300 mg, and metoclopramide, 10 mg, in the morning. Patients in group IX received ranitidine, 300 mg, at bedtime and in the morning; while group X patients received ranitidine as in group IX, and in addition, received metoclopramide, 10 mg, in the morning. Patients with gastric pH ≤2.5 or gastric content volume ≥20 ml were defined to be at risk of pulmonary damage in the event of aspiration. Patients in group I had a mean gastric pH of 2.33 with 73% of the patients with pH ≤2.5, while 47% of the patients presented with a combination of pH ≥ 2.5 and volume ≥ 20 ml. Ranitidine and metoclopramide independently and in combination significantly reduced risk factors. Metoclopramide reduced the proportion of patients with a gastric pH ≤ 2.5 to 27%, and reduced those with combined risk factors to 13%. Ranitidine with or without metoclopramide (groups III-X) strikingly reduced gastric acidity and had a modest effect in reducing the volume. In the eight groups of patients receiving ranitidine, only two patients (1.6%) had pH ≥ 2.5, while only one patient (0.8%) had a combination of pH ≥ 2.5 and volume s 20 ml. Ninety-three percent of patients in groups III-X had pH ≥ 5.0, while 79% had gastric volumes < 10 ml. There were no significant differences in modification of risk factors among, eight groups receiving either ranitidine or ranitidine and metoclopramide by different dosages and modes of administration.