Somatosensory evoked potentials during mild hypothermia after cardiopulmonary resuscitation.
OBJECTIVE
In patients who remain in a coma after cardiopulmonary resuscitation (CPR), the bilateral absence of cortical N20 responses of median nerve somatosensory evoked potentials (SSEP) 24 hours after admission invariably correlates with a poor neurologic outcome. Nowadays, CPR patients are treated with mild hypothermia, with simultaneously administered sedative drugs, hampering clinical neurologic assessment. We investigated whether SSEP performed during hypothermia can reliably predict a poor neurologic outcome.


METHODS
Between July 2006 and April 2008, this multicenter prospective cohort study included adult comatose patients admitted after CPR and treated with induced mild hypothermia (32-34 degrees C). SSEP was performed during hypothermia, and in patients who remained comatose after rewarming, a second SSEP was performed. Neurologic outcome was assessed 30 days after admission with the Glasgow Outcome Scale.


RESULTS
Seventy-seven consecutive patients were included in 2 hospitals. In 13 patients (17%), the cortical N20 response during hypothermia was bilaterally absent. In 9 of these 13 patients in whom SSEP could be repeated during normothermia, the N20 response was also absent, yielding a positive predictive value of 1.00 (95% confidence interval [CI] 0.70-1.00). All 13 patients with absent SSEP during hypothermia had a poor neurologic outcome, yielding a positive predictive value of 1.00 (95% CI 0.77-1.00).


CONCLUSIONS
The results of this pilot study show that bilaterally absent cortical N20 responses of median nerve somatosensory evoked potentials performed during mild hypothermia after resuscitation can predict a poor neurologic outcome. We started a larger multicenter prospective cohort study to confirm these results.
Bouwes
A
A
Department of Intensive Care, C3-423, Academic Medical Center, P.O. Box 22660, 1100 DD, Amsterdam, the Netherlands. a.bouwes@amc.uva.nl
Binnekade
J M
JM
Zandstra
D F
DF
Koelman
J H T M
JH
van Schaik
I N
IN
Hijdra
A
A
Horn
J
J
D000328:Adult; D000368:Aged; D016887:Cardiopulmonary Resuscitation; D003128:Coma / Q000503:physiopathology*; D015986:Confounding Factors, Epidemiologic; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D010865:Pilot Projects; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020127:Recovery of Function; D012720:Severity of Illness Index; D013997:Time Factors; D016896:Treatment Outcome