A patient with a history of opioid use is scheduled for nitrous oxide sedation. He denies recent drug use, but you notice a strong odour of cannabis. What is the MOST appropriate action?

Correct answer: A. Reschedule and instruct the patient not to use substances before the appointment

• A. Correct. RESCHEDULE. Acute cannabis intoxication causes tachycardia, unpredictable anxiety or paranoia, and additive CNS depression with nitrous oxide. Beyond the pharmacology, an intoxicated patient cannot give valid informed CONSENT. Document the finding objectively, explain why treatment is being deferred, and give clear instructions about abstaining before the rescheduled visit.
• B. This is not a medical emergency requiring hospital referral.
• C. Proceeding is unsafe. Recent cannabis use combined with nitrous oxide potentiates CNS depression, and cannabis independently produces TACHYCARDIA that can be dangerously amplified.
• D. Reducing the concentration does not eliminate the unpredictable interaction or the cardiovascular risk.