Do patients with cannabinoid hyperemesis syndrome have an increased risk of post-anesthesia intractable vomiting?

Cannabinoid Hyperemesis Syndrome and Post-Anesthesia Intractable Vomiting Risk

Patients with cannabinoid hyperemesis syndrome (CHS) are at increased risk for post-anesthesia intractable vomiting and should receive enhanced prophylactic antiemetic therapy perioperatively. 1

Evidence for Increased PONV Risk

The British Journal of Anaesthesia consensus guidelines explicitly recognize that postoperative nausea and vomiting (PONV) in patients with cannabinoid withdrawal syndrome (CWS) or CHS could contribute to morbidity and diagnostic uncertainty regarding other causes of nausea and vomiting. 1 While acknowledging limited direct evidence, the expert panel determined that administering additional PONV prophylaxis to patients who consume significant quantities of cannabis is of potential benefit and unlikely to result in harm. 1

Pathophysiological Mechanism

The underlying mechanism involves dysregulation of the endocannabinoid system's control over emesis. CB1 receptors are densely distributed in the dorsal vagal complex, which is critically important in the neurocircuits controlling emesis. 1 Chronic cannabis use leads to:

• Loss of negative feedback on the hypothalamic-pituitary-adrenal axis, resulting in increased vagal nerve discharges that contribute to vomiting 1
• Altered gastric motility and emptying through peripheral CB1 receptor activation 1, 2
• Disruption of normal stress response and allostasis mechanisms 3

Perioperative Management Algorithm

Preoperative Identification

Screen for CHS risk factors in all patients:

• Cannabis use >4 times per week for >1 year 1
• History of cyclic vomiting episodes (≥3 annually) 1, 4
• Characteristic hot water bathing behavior for symptom relief (reported in 71% of CHS cases) 1
• Daily cannabis consumption >1.5g inhaled, >300mg CBD oil, or >20mg THC oil 1

Enhanced PONV Prophylaxis

For patients meeting high-risk cannabis consumption criteria, administer multimodal antiemetic prophylaxis that differs from standard PONV protocols. 1 The American Gastroenterological Association and British Journal of Anaesthesia recommend:

• Avoid standard antiemetics alone (ondansetron, metoclopramide) as they have limited effectiveness in CHS patients 5, 6, 7
• Prioritize butyrophenones: Haloperidol or droperidol (most commonly 0.625mg IV) have demonstrated superior efficacy, reducing hospital length of stay by nearly 50% (6.7 vs 13.9 hours, p=0.014) 5, 6
• Consider benzodiazepines for their sedating and anxiolytic effects, which address the stress-mediated component of CHS 1, 3, 7
• Add topical capsaicin 0.1% applied to the abdomen, which activates TRPV1 receptors and has shown consistent benefit 1, 5, 4, 7

Anesthetic Considerations

Cannabis users may require higher doses of anesthetic agents to achieve adequate depth of anesthesia. 1 Specifically:

• Consider using processed depth of anesthesia EEG monitoring (BIS) for patients with heavy cannabis use 1
• Have additional anesthetic medication available for induction and maintenance 1
• Recognize that acute intoxication may paradoxically reduce anesthetic requirements while chronic use increases tolerance 1

Postoperative Pain Management

Anticipate higher postoperative analgesic requirements in chronic cannabis users. 1 However:

• Avoid opioids as they worsen nausea and carry high addiction risk in this population 1, 5
• Consider multimodal non-opioid analgesia strategies 1
• Be aware that cannabis withdrawal (beginning 48 hours after abstinence) may contribute to increased pain perception 1, 5

Critical Diagnostic Pitfalls

CHS is frequently underdiagnosed or misdiagnosed due to limited clinician awareness, leading to extensive unnecessary testing. 5, 2, 4 Key considerations:

• Patients paradoxically report that cannabis helps relieve their symptoms, leading to continued use and worsening of the underlying condition 5, 2
• The prevalence of CHS is rising with cannabis legalization and higher THC concentrations in modern products 5, 2
• Rule out life-threatening conditions first (acute abdomen, bowel obstruction, mesenteric ischemia, pancreatitis, myocardial infarction) before attributing symptoms solely to CHS 1, 5

Postoperative Complications

Beyond intractable vomiting, CHS patients face additional perioperative risks:

• Severe dehydration and electrolyte abnormalities (particularly potassium and magnesium depletion) 5, 2, 8
• Acute kidney injury and rhabdomyolysis from prolonged vomiting 8
• Diagnostic uncertainty that may delay recognition of other postoperative complications 1
• Potential contribution to postoperative ileus through gut motility effects 2

Definitive Management

Cannabis cessation is the only definitive treatment for CHS and should be strongly recommended preoperatively when feasible. 1, 5, 4 For long-term management, tricyclic antidepressants (amitriptyline 75-100mg at bedtime, starting at 25mg with weekly titration) are the mainstay of preventive therapy. 1, 4