Curriculum · Mental Health / Psychiatry
Opioid overdose and its reversal
What it is
Opioid overdose is defined on the management algorithm by a respiratory rate under 12 breaths per minute when the patient is not asleep. Opioid toxicity is a clinical diagnosis. Naloxone is a short acting opioid antagonist, indicated for the reversal of the respiratory depression associated with narcotic overdoses. It is an effective antagonist for all opiates and many synthetic opioid compounds, and it is ineffective in reversing coma due to any other cause.
How it presents
Pinpoint pupils with a low respiratory rate in a comatose patient is the combination that prompts a trial of naloxone. Bradycardia may be seen on the ECG. The blood gas shows the respiratory failure: a venous gas with a pH of 7, a PaCO2 of 82, a PaO2 of 20 and a lactate of 7 is the kind of result produced.
How it is diagnosed
The diagnosis is clinical. On the algorithm for the patient with an altered mental status, once intravenous glucose has been given and has not improved matters, you ask whether the pupils are pinpoint, what the history is, what urine toxicology screening shows, and whether there is improvement after naloxone; a yes leads to opioids poisoning and ED observation. After resuscitation is initiated the investigations are a urine drug screen, an ECG for bradycardia, CT head, RFT, CK, a repeat blood gas to see the response to treatment, and a CXR. Co-ingestion is looked for, aspirin and paracetamol in particular.