Gastric Ultrasound Assessment for Patients Taking Cannabis

Cannabis use in the United States has continued to increase in recent years, particularly in the adult population. Ease of access through legalization paired with improved public perception has contributed to the uptick in cannabis use. The subset of cannabis users suffering from pain who present for surgery pose a risk for perioperative aspiration due to the slowing of gastric motility due to cannabis use. There is currently no adapted NPO guideline to account for cannabis use.

Gastric Ultrasound (GUS) can be used as a bedside tool for assessing a patient's stomach contents and risk of aspiration. GUS can identify whether a patient's stomach is empty or filled with clear liquid, thick liquid, or solid food. The volume of the stomach can be accurately calculated if there is clear liquid content. A full stomach is categorized as those with solid or thick liquid content or with clear liquid measuring more than 1.5 ml/kg body weight. As GUS is noninvasive and does not pose risk to patients, it is a useful tool assessing aspiration risk in the preoperative period.

Inclusion criteria

• Any patient reporting preoperative cannabis usage within 1 month of surgery date

Exclusion criteria

• Patient refusal to participate
• Patient with gastric bypass or any other gastric surgery
• Large hiatal hernia
• Patients with large ascites
• Patients on peritoneal dialysis
• Emergency surgery
• Pre-existing diagnosis of gastroparesis
• Parkinson's disease
• Diabetes
• Currently taking metformin
• Chronic kidney disease stage 3 or higher
• Creatinine ≥ 1.2
• Esophageal surgery
• Currently taking GLP1 agonist medication