Opioid Pharmacology and Toxicity

A 32-year-old male patient with severe postoperative pain is administered intravenous morphine 10 mg. Two hours later, he develops severe respiratory depression (RR 6/min), pinpoint pupils, and altered consciousness. Which investigation would be most specific in confirming acute opioid toxicity?

A 42-year-old woman with chronic pain on long-term morphine (120 mg/day) presents to the perioperative clinic for elective knee arthroplasty. She reports tolerance and breakthrough pain despite the current dose. During preoperative assessment, she asks about pain management during and after surgery. What is the most appropriate next step?

A 42-year-old man with chronic pain from metastatic cancer is on morphine 60 mg/day. He presents to the emergency department with severe respiratory depression (RR 8/min), pinpoint pupils, and altered mental status. His wife reports he took an extra dose 2 hours ago. Arterial blood gas shows pH 7.20, PaCO₂ 85 mmHg, PaO₂ 55 mmHg. What is the immediate pharmacological intervention?

A 42-year-old woman on chronic opioid therapy for cancer pain develops acute chest pain, dyspnea, and hypotension 30 minutes after receiving a bolus of intravenous morphine. Cardiac auscultation reveals no new murmurs. Which investigation is most specific for diagnosing opioid-induced anaphylactoid reaction (non-IgE-mediated mast cell degranulation)?

During a postoperative audit of opioid-related adverse events in your hospital, the most common cause of acute opioid-induced respiratory depression in the recovery room is identified. Which of the following is the most frequent culprit?