Coma: clinical features can help diagnose opiate overdose.

Clinical bottom line (level 2b)

  1. Patients with an altered mental state who have the following likely to have had an opiate overdose:
    • decreased respiratory rate (less than 13 breath/min) (LR+14)
    • circumstantial evidence of opiate abuse (drug paraphernalia where found, needle track marks on skin, history of iv drug use by bystanders) (LR+14)
    • pinpoint pupils (LR+5.1)
  2. Patients with none of these are less likely to have had an opiate overdose (LR-0.11) .
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:
    • respiration < 13 breaths/min
    • pinpoint pupils
    • circumstantial evidence: presence of drug paraphernalia at the scene, needle track marks on the skin, or a history of iv drug use given by bystanders
    • any of the above

    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 LR-
    (95% CI)    		 post-test probability
    respirations < 13 breaths/min 20 13 14
    (7.8 to 24)     		61% 0.21
    (0.097 to 0.47)     		2.3%
    pinpoint pupils 19 33 5.1
    ( to )     		37% 0.28
    (0.14 to 0.57)     		3.1%
    circumstantial evidence 17 11 14
    (7.2 to 26)     		61% 0.34
    (0.19 to 0.60)     		3.7%
    any of the above 23 53 3.8
    (3.0 to 5.0)     		30% 0.11
    (0.028 to 0.40)     		1.2%
    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