Gastric fluid pH in patients receiving cimetidine

Area of Science:

• Anesthesiology
• Pharmacology
• Gastroenterology

Background:

• Elevated gastric fluid pH is crucial for reducing aspiration risk during anesthesia.
• Preanesthetic fasting is standard, but gastric acidity can remain a concern.
• Cimetidine is a histamine H2-receptor antagonist used to reduce gastric acid production.

Purpose of the Study:

• To evaluate the efficacy of oral cimetidine in increasing gastric fluid pH in fasting adult patients before anesthetic induction.
• To determine the optimal timing for oral cimetidine administration to maximize gastric pH elevation.

Main Methods:

• A study involving 150 fasted adult patients undergoing anesthesia.
• Gastric fluid pH was measured immediately after anesthetic induction.
• Patients received either oral cimetidine (300 mg) at different timings or no cimetidine, alongside standard morphine-atropine preanesthetic medication.

Main Results:

• Oral cimetidine administered the evening before surgery raised gastric pH above 2.5 in 78% of patients.
• Administering oral cimetidine 60-90 minutes before anesthetic induction increased gastric pH above 2.5 in 84% of patients.
• Only 40% of patients not receiving cimetidine had a gastric pH above 2.5.

Conclusions:

• Oral cimetidine administration 60-90 minutes before anesthetic induction is a practical and effective method to increase gastric fluid pH.
• This strategy significantly improves the gastric pH in the majority of fasting adult patients, potentially reducing aspiration risk.
• Cimetidine represents a valuable tool in anesthetic management for optimizing gastric conditions prior to procedures.