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Heroin OD With Naloxone – Is 2h Observation Enough?

May 21, 2019

Written by Clay Smith

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In heroin users specifically, 5% needed either repeat naloxone or oxygen > 2 hours after initial naloxone reversal. Observation for 3 hours may be safer, especially for those with polysubstance abuse.

Why does this matter?
Some opioids have a longer half life than naloxone. So, while patients may initially have opioid reversal, they may have recurrent somnolence or worse, respiratory depression when naloxone wears off. How long should patients with heroin overdose (OD) be watched in the ED? Classic teaching is 4-6 hours. The HOUR clinical decision rule suggested that 1-hour was enough if patients met all low-risk criteria. EMS studies have found a very low adverse event rate in patients who are reversed in the field and who refuse transport to the ED. In this large cohort of heroin users who came to the ED, how often did they need intervention >2 hours from naloxone?

Is it 2 or 3 or 4 hours?
This was a retrospective chart review of a single center in Louisville focusing on 806 patients with heroin OD who received naloxone for reversal. They tried to exclude patients with extended release oral opiate ingestion. Average naloxone dose was 3.08mg, but the route was not specified. The intervention rate past 2 hours, which included repeat naloxone or need for O2, was 4.6% (37 patients). It was 1.9% (15 patients) after 3 hours and 0.9% (7 patients) after 4 hours. Patients with polysubstance abuse were more likely to need repeat naloxone. Patients with preexisting cardiac or pulmonary disease did not fare worse. A key limitation is that the authors relied on patient self-reporting of heroin use, which is fraught and could have introduced recall bias. The authors’ take home was that a 3-hour observation period may be the best balance of safety and ED throughput, with longer observation for those with polysubstance abuse. In reality, this is challenging. Heroin is often adulterated with other compounds, like fentanyl. And it seems to me like patients are frequently polysubstance users. It can also be hard to coax these patients into staying once the opiate is reversed. Bottom line: if you can get heroin users to stay for 3 hours, they are probably safe to go home at that point.

Retrospective Review of Need for Delayed Naloxone or Oxygen in Emergency Department Patients Receiving Naloxone for Heroin Reversal. J Emerg Med. 2019 Apr 5. pii: S0736-4679(19)30121-0. doi: 10.1016/j.jemermed.2019.02.015. [Epub ahead of print]

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Reviewed by Thomas Davis

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