Emergency cimetidine prophylaxis against acid aspiration

Area of Science:

• Anesthesiology
• Gastroenterology
• Critical Care Medicine

Background:

• Emergency surgical patients often have low gastric pH, increasing aspiration risk.
• Acid aspiration can lead to pulmonary injury.
• Cimetidine is a potential prophylactic agent to increase gastric pH.

Purpose of the Study:

• To evaluate the timing and efficacy of preoperative intravenous cimetidine.
• To assess cimetidine's ability to increase gastric pH in emergency surgical patients.
• To determine the proportion of patients achieving a safe gastric pH ( > 2.5).

Main Methods:

• Administration of 300 mg intravenous cimetidine preoperatively.
• Measurement of gastric pH at intubation and extubation.
• Analysis of the interval between cimetidine administration and intubation.

Main Results:

• Two-thirds of patients initially had gastric pH <= 2.5 (mean 2.13).
• Cimetidine significantly increased mean gastric pH to 3.25 at intubation (mean interval 59 minutes).
• Twenty percent of patients did not achieve pH > 2.5 pre-intubation; mean extubation pH was 5.09.

Conclusions:

• Preoperative intravenous cimetidine effectively increases gastric pH in most emergency surgical patients.
• It may offer protection against acid-induced aspiration pulmonary injury.
• Efficacy is variable, with a significant minority failing to reach target pH.