Use of I.M. Ranitidine for the Prophylaxis of Aspiration Pneumonitis in Obstetrics

Abstract

Twenty patients who underwent elective Caesarean section received ranitidine 150 mg by mouth 8-14 h, and 50 mg i.m. 90 min, before surgery. Intraoperative gastric aspiration resulted in contents with a pH greater than 2.5 and volume less than 25 ml in all patients (mean pH 6.5 (SD 0.8); mean volume 9.0 (SD 7.2) ml). Sixty patients in labour, who received ranitidine 50 mg i.m. 6-hourly, underwent emergency surgery. Half of this group received, in addition, a single preinduction dose of either 15 or 30 ml of sodium citrate 0.3 mol litre-1. A further 30 patients who remained unmedicated during labour and required emergency surgery received a preinduction dose of 15 or 30 ml of sodium citrate 0.3 mol litre-1 alone. Ranitidine medication resulted in a mean aspirated gastric volume of 31.4 (26.6) ml and pH of 5.3 (2.1); five of 30 patients had a pH less than 2.5. The addition of sodium citrate 0.3 mol litre-1 resulted in gastric pH greater than 2.5 in all patients and a mean gastric volume of 43.2 (38.3) ml. The group who received only sodium citrate 0.3 mol litre-1 had a mean pH of 5.3 (1.1) and a mean volume 122.7 (98.2) ml.

Aspiration Prevention and Prophylaxis

“…136 Manchikanti and associates compared surgical outpatients given Bicitra 15 or 30 mL PO with a matched control group. 146 In other reports, however, sodium citrate failed to alter gastric fluid pH in surgical patients. Of the control patients, 88% had a gastric content pH of 2.5 or less, in contrast to 32% of those given Bicitra 15 mL and only 16% of those given Bicitra 30 mL.…”

“…150 Other side effects sporadically associated with cimetidine include confusion, dizziness, headaches, and diarrhea, although these have not been reported to occur with single-dose preoperative administration. 128,132,146 RANITIDINE. 129,131,132 As a result, cimetidine may elevate the blood concentrations of other drugs that are cleared by the liver, including warfarin, propranolol, diazepam, theophylline, phenytoin, meperidine, bupivacaine, and lidocaine.…”

“…128,129,132 Cimetidine competitively inhibits the hepatic mixedfunction oxidase system (cytochrome P450 enzyme) and also reduces hepatic perfusion. 1,58,132,146,151 Smith and coauthors reported that ranitidine 50 mg, given IV over 2 minutes to 20 critically ill patients, led to variable, transient reductions in mean arterial pressure and systemic vascular resistance. Clinically, this seems to be a greater concern with long-term use than with one-or two-dose administration.…”

Perioperative fasting and feeding in adults, obstetric, paediatric and bariatric population: Practice Guidelines from the Indian Society of Anaesthesiologists

“…We identified 12 comparative trials (including one from India),[ 172 173 174 175 176 177 178 179 180 181 182 183 ]2 systematic reviews[ 184 185 ] and 3 surveys[ 186 187 188 ] on aspiration prophylaxis in obstetric units. The studies had low level of evidence due to small sample sizes and varied drugs employed for prophylaxis.…”

“…[ 174 ] Studies comparing the use of sodium citrate and H 2 receptor blockers, particulate antacids and use in elective vs emergency surgeries, have found that they increased the pH of gastric content but the residual gastric volumes are also increased (LOE-Very Low to Low). [ 175 176 177 178 179 180 ] Studies comparing the effect of proton pump inhibitors and H 2 receptor blockers on residual gastric volume found that the volumes were lower when H 2 receptor blockers and proton pump inhibitors were administered the night before and morning of surgery than when administered only on the morning of surgery (LOE- Very Low to Low). [ 181 182 183 ]…”