Pharmacology · patient case question
Which agent poses the greatest risk of respiratory depression in this patient?
Patient case: Restorative treatment planned for a patient with obstructive sleep apnoea
Patient: Male, 54 years old
Chief Complaint: “I have several teeth that need fillings and I would rather be sedated.”
Background: Obstructive sleep apnoea, uses CPAP nightly. BMI 34. Loud snoring, witnessed apnoeas, daytime somnolence. No other medical history.
Vital Signs: BP 138/86 mmHg · HR 78 bpm · SpO₂ 96% on room air · Mallampati class III · neck circumference 44 cm
Findings: Deep caries in four posterior teeth requiring restoration. No acute symptoms.
Show answer and explanation
Correct answer: D. Diazepam
- A. Local anaesthetic with a vasoconstrictor has no respiratory depressant action at dental doses, and profound local anaesthesia is exactly what allows the case to be done without systemic sedation.
- B. Acetaminophen has no effect on respiratory drive.
- C. Ketorolac is a parenteral NSAID. It carries gastrointestinal, renal and bleeding risks but no respiratory depressant effect.
- D. CORRECT. DIAZEPAM, like all BENZODIAZEPINES, produces dose-dependent RESPIRATORY DEPRESSION and reduces upper airway muscle tone — the precise mechanism that already causes this patient's apnoeas. Obstructive sleep apnoea patients are unusually sensitive: sedation deepens the obstruction, blunts the arousal response that normally terminates each apnoeic episode, and the long half-life of diazepam and its active metabolites prolongs the exposure well beyond the appointment.
Note: Manage the sleep apnoea patient by AVOIDING the problem: profound local anaesthesia, short appointments, an upright or semi-upright chair position rather than supine, and continuous pulse oximetry if any sedation is used at all. Nitrous oxide with oxygen is the safest sedative option because it is rapidly reversible and maintains airway tone. OPIOIDS and BENZODIAZEPINES are the two classes to avoid or minimise. If deeper sedation is genuinely required, it belongs in a monitored setting with an anaesthesia provider.