Mitigating Aspiration Risk During Anesthesia

Preoperative Fasting Guidelines

• The American Society of Anesthesiologists recommends clear liquids may be ingested up to 2 hours before procedures requiring general anesthesia, regional anesthesia, or procedural sedation 1, 2
• The American Society of Anesthesiologists recommends breast milk may be ingested up to 4 hours before elective procedures 1, 2
• The American Society of Anesthesiologists recommends infant formula may be ingested up to 6 hours before elective procedures 1, 2
• The American Society of Anesthesiologists recommends light meals should be avoided for at least 6 hours before procedures 3, 4
• The American Society of Anesthesiologists recommends fried or fatty foods or meat may require extended fasting time of 8 hours or more 5, 4
• Examples of clear liquids include water, fruit juices without pulp, carbonated beverages, carbohydrate-rich nutritional drinks, clear tea, and black coffee, as defined by the American Society of Anesthesiologists 1, 2
• Alcoholic beverages should not be included as clear liquids, according to the American Society of Anesthesiologists 1, 2

Risk Assessment and Patient Evaluation

• The American Society of Anesthesiologists recommends performing thorough preoperative assessment including review of medical records, physical examination, and patient interview 2, 5
• The American Society of Anesthesiologists recommends evaluating for risk factors including gastroesophageal reflux disease, dysphagia symptoms, gastrointestinal motility disorders, and metabolic disorders like diabetes mellitus 2, 5
• The American Society of Anesthesiologists recommends verifying patient compliance with fasting requirements at the time of procedure 2, 5

Pharmacologic Interventions

• The American Society of Anesthesiologists recommends medications that block gastric acid secretion, like famotidine, may be administered to patients at increased risk of pulmonary aspiration 2, 5, 6
• Oral famotidine 40 mg administered at least 3 hours before surgery can reduce gastric volume and increase gastric pH, according to the American Society of Anesthesiologists 6
• The American Society of Anesthesiologists recommends gastrointestinal stimulants may be administered to patients at increased risk 2, 5
• The American Society of Anesthesiologists recommends antiemetics may be administered to patients at increased risk of postoperative nausea and vomiting 2, 5
• The American Society of Anesthesiologists recommends routine administration of preoperative medications that block gastric acid secretion is not recommended for patients without apparent increased risk 2, 5
• The American Society of Anesthesiologists recommends routine administration of preoperative gastrointestinal stimulants is not recommended for patients without apparent increased risk 2, 5
• The American Society of Anesthesiologists recommends administration of preoperative anticholinergics to reduce aspiration risk is not recommended 2, 5, 7

Preoperative Gastric Acid Suppression for Cesarean Section

Evidence-Based Recommendation

• The American Society of Anesthesiologists recognizes H2-receptor antagonists and proton pump inhibitors as options for blocking gastric acid secretion, but does not routinely recommend either for patients without increased risk, however, obstetric patients undergoing cesarean section represent a higher-risk population 8, 9, 10
• The American Society of Anesthesiologists guidelines state that routine prophylaxis is not recommended for healthy patients without increased aspiration risk, but obstetric patients undergoing cesarean section are considered at increased risk 8, 10, 11

Clinical Algorithm for Cesarean Section

• Administering nonparticulate antacid immediately before induction is recommended, as stated in the 2007 ASA Obstetric Anesthesia guidelines 10

Important Caveats

• The ASA guidelines support the use of nonparticulate antacids and note that H2-receptor antagonists are effective in obstetric patients undergoing cesarean section 10

Aspiration Prophylaxis with IV Famotidine

Patient Selection and Prophylaxis

• The American Society of Anesthesiologists recommends H2-receptor antagonists like famotidine for patients with identifiable risk factors, such as emergency surgery, obesity, pregnancy, difficult airway, gastroesophageal reflux disease, delayed gastric emptying, diabetes mellitus, and gastrointestinal motility disorders, to reduce aspiration risk 12

IV Famotidine Dosing Protocol

• Administering IV famotidine 20 mg at least 15-30 minutes before endotracheal intubation ensures adequate suppression of gastric secretion at the time of intubation, with a duration of action extending over 4 hours, providing protection throughout the perioperative period 12

Expected Clinical Outcomes

• IV famotidine significantly increases gastric pH and decreases gastric volume compared to placebo, reducing the percentage of at-risk patients from 40% to 15-20% in emergency surgery patients 12
• The American Society of Anesthesiologists recommends combining famotidine with appropriate fasting guidelines, including clear liquids up to 2 hours before procedures, light meals avoided for at least 6 hours, and fatty foods or meat requiring 8 hours or more fasting, to optimize aspiration prevention 12