Coma: a response to naloxone could help diagnose opiate overdose.

Clinical bottom line (level 2b)

  1. Few patients with altered mental state responded to naloxone.
  2. Patients with an altered mental state who responded to naloxone were more likely to have taken an opiate overdose (LR+28) , and patients who fail to respond were less likely to have taken an opiate overdose (LR-0.19) .
  3. A partial response was unhelpful at diagnosing opiate overdose.
Hoffman et al: Annals of Emergency Medicine 1991; 20 (3): 246-252
Expires September 2003

The study

Setting: paramedic units, urban community, USA

246 patients (aged ?, ?% male) with altered mental consciousness who received naloxone

Excluded if
  • no final diagnosis available


    • All patients received 50% glucose intravenously.
    Independent blinded reference standard, applied in all patients from a non-consecutive appropriate spectrum.
    Reference standard:
    • physician review of hospital chart
    Diagnostic test: response to naloxone: complete awakening, partial or questionable response or absence of response

    The evidence

    pre-test probability of opiate overdose: 10%, (95% CI: 6.4% to 14%)

    diagnostic test opiate overdose no opiate overdose LR
    (95% CI)    		 post-test probability
    complete response to naloxone 19 6 28
    (12 to 64)     		76%
    partial or equivocal response to naloxone 2 24 0.74
    (0.18 to 2.9)     		7.7%
    no response to naloxone 4 191 0.19
    (0.075 to 0.46)     		2.1%
    total 25 221

    Comments

    1. 3.4% of patients had a complete response to naloxone.

    Citation

    1. Hoffman JR, Schriger DL, Luo JS, et al: the empiric use of naloxone in patients with altered mental status: a reappraisal. Annals of Emergency Medicine 1991; 20 (3): 246-252
    Contributor: Chris Ball and Clare Wotton, September 1999
    Reviewer: Malcolm Daniel

    Clinical Question.
    Patient altered mental consciousness
    Intervention or Exposure complete recovery following naloxone
    Outcome opiate overdose