Coma: anoxic-ischemic: most patients died or remained in a vegetative state

Clinical bottom line (level 2a)

  1. 70% of patients in an anoxic-ischemic coma died or remained in a persistent vegetative state.
  2. Patients were at increased risk of a bad outcome if they had any of
    • no cerebral response to somatosensory evoked potentials after one week
    • GCS motor score =1 at day 3
    • absent pupillary response at day 3
    • burst activity or flat EEG after one week
Zandbergen et al: Lancet 1998; 352: 1808-1812
Expires October 2003

The study

Systematic review of all studies of
  • Patients: anoxic-ischaemic coma
  • Intervention: early neurological or neurophysiological features
  • Outcome: death or survival in a vegetative state


    • Articles found in English, German, French using Medline, Embase, 1966 to 1997 (search terms: anoxia (cerebral), ischaemia (cerebral), heart arrest, hypotension, shock, postoperative complications, respiratory insufficiency, resuscitation or drowning combined with coma or Glasgow Coma Scale ) and and reference lists of retrieved articles

    Selection criteria: see above
    Appraisal criteria: not given
    Articles excluded if:
    • unable to distinguish patients with anoxic-ischaemic coma from other causes
    • aged < 10
    • selected or non-consecutive cases
    • tests poorly described
    • inability to extract data for individual tests


    33 studies found

    The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)
    death or vegetative state ? 859/1249 69%
    (66% to 71%)

    prognostic factor for
    death or vegetative state     		time to outcome adjusted RR
    (95% CI)    		 NNF+
    (95% CI)
    somato-sensory evoked potential: bilateral absence of N20 (earliest cortical response after median nerve stimulation) during first week ? 1.78
    (1.63 to 1.93)     		2
    (2 to 3)
    GCS motor response = 1 on day 3 ? 1.76
    (1.50 to 2.06)     		2
    (2 to 3)
    absent pupillary reactions to light on day 3 ? 1.64
    (1.42 to 1.89)     		3
    (2 to 4)
    burst-suppression or isoelectric EEG during first week ? 2.74
    (2.31 to 3.25)     		2
    (1 to 2)

    Comments

    1. Failure to exclude retrospective or unblinded studies makes this systematic review more open to bias.
    2. Unclear how the data was combined - presented as likelihood ratios rather than odds ratios or relative risks. These relative risks have been calculated from data in the article.
    3. No information on length of follow-up provided.

    Citation

    1. Zandbergen EG, de Haan RJ, Stoutenbeek CP, et al: systematic review of early prediction of poor outcome in anoxic-ischaemic coma. Lancet 1998; 352: 1808-1812
    Contributor: Chris Ball and Clare Wotton, October 1999
    Reviewer: Malcolm Daniel

    Clinical Question.
    Patient coma
    Intervention or Exposure clinical and EEG findings
    Outcome PVS, death