Diagnosis of drug overdose by rapid reversal with naloxone

Diagnosis of drug overdose by rapid reversal with naloxone

Report by Jenifer Barrie, Medical student

Search checked by Gabby May, Clinical Fellow in Paediatric Emergency Medicine

Manchester Medical School, Manchester, UK

Abstract

A short‐cut review was carried out to establish whether naloxone may have an awakening effect in patients who have not taken opiates, thereby clouding its use as a diagnostic manoeuvre. The clinical bottom line is that opioid antagonists are able to reverse symptoms such as altered consciousness in patients who have not taken an overdose of opiates. It is unclear in which conditions or circumstances this occurs.

Clinical scenario

A 36‐year‐old man is brought into the emergency department by ambulance with a suspected opiate overdose. He has pinpoint pupils and bradypnoea, which is reversed by administration of naloxone. However, there is no evidence of intravenous drug misuse such as needle track marks. We wonder if naloxone can be used to reverse and therefore diagnose any other conditions.

Three‐part question

[In adults who present to the emergency department with suspected acute opiate overdose] is [reversal with naloxone] [diagnostic ONLY of opiate use]?

Search strategy

Medline 1966 to August 2006 using the OVID interface. Embase 1980 to 2006. CINHAL 1982 to 2006. [{exp DIAGNOSIS/OR DIAGNOSIS.mp. OR sensitiv$.mp OR specificit$.mp} AND {exp. naloxone OR Narcan.mp OR opiate anatgonist.mp} AND {exp. Narcotics AND exp. Overdose}] Limit to humans and English

Cochrane Database 2006: naloxone and overdose

Search outcome

Medline: 757 results were found, of which 3 were relevant. Embase: 95 results were found. No further relevant papers. CINHAL: 14 papers were found. No further relevant papers. The Cochrane library: No new papers found.

Relevant papers

Table 3.

Author, date, country		Patient group		Study type (level of evidence)		Outcomes		Key results		Study weaknesses
Kaplan et al, 1999, USA		Adults in nine centres who had suspected opiate overdose. 63 received 1 mg nalmefene, 55 received 2 mg nalmefene and 58 received naloxone		Double‐blind randomised study.		Opioid positivity in patients and response to each drug.		Opioid positivity recorded in 1 mg nalmefene (30/63), 2 mg nalmefene (23/55), naloxone (24/58); all patients responded		Does not state the diagnosis in patients who did not have an opiate overdose but responded to the drug; toxicological data were incomplete in 31 patients; opioid‐positive patients may have had other causes of altered consciousness; no patient follow‐up of late complications
Hoffman et al, 1991, USA		730 patients with altered mental status, who received naloxone in two urban paramedic‐base teaching hospitals		Retrospective review of paramedic run sheets, audiotapes and available hospital records		Are clinical criteria and response to naloxone definitive diagnosis of opiate overdose		76% of complete responders, 8% of partial responders and 2% of non‐responders had taken an opiate overdose		Does not state the diagnosis of patients who responded to naloxone, but had not taken an overdose of opiates; toxicological analysis was not carried out to prove opiate overdose; there were non‐responders and incomplete sampling; the sample size was small for sensitivity and specificity calculations; paramedics may have incorrectly classified patients response ot naloxone; overdoses may have been mixed, so response to naloxone would not be as good
Jeffreys et al, 1983		Several studies looking at the use of narcan in patients with opiate, non‐opiate and ethanol poisoning		Review		31 cases of non‐opioid poisoning		6 patients who had no evidence of opiate intoxication improved with narcan;		Database review from national poisons database; potential bias from selective reporting
						300 cases of suspected ethanol induced coma		49 showed reversal of coma with narcan (in 38 cases, ethanol was the sole cause of coma)
						Are clinical criteria and response to naloxone definitive diagnosis of opiate overdose		25 patients (3.4%) responded completely to narcan

Comments

Naloxone is often used, both for its diagnostic and therapeutic use, in patients presumed to have taken opiates. This BET looked at the question of whether naloxone can improve the decreased Glasgow Coma Score and respiratory depression associated with other conditions, especially other overdoses. These three studies, although not specifically written to answer the question, seem to show that a proportion of patients who have not taken opiate may respond to naloxone. However, not all the patients underwent toxicological analysis to give a final definite diagnosis, and some patients who seemed to respond to narcan but were documented as non‐opiate overdoses may have just coincidentally improved. ?There seems to be no detrimental effects from the use of narcan in non‐opiate overdoses.

Clinical bottomline

The evidence suggests that opioid antagonists are able to reverse symptoms, such as altered consciousness, in patients who have not taken an overdose of opiates. It is unclear in which conditions or circumstances this occurs.