NEW YORK (Reuters Health) – Hypothermia and the medications used with it can influence the common predictors of neurologic outcome after cardiac arrest, according to findings published online in the November 8th Annals of Neurology.
“Findings on physical examination performed serially over time remain the most reliable predictors of outcome after cardiac arrest, regardless of whether patients are treated with hypothermia or not,” Dr. Alejandro A. Rabinstein from Mayo Clinic, Rochester, Minnesota told Reuters Health in an email. “When prognosticating in patients treated with hypothermia, it is important to be especially prudent because the effect of sedatives (used as part of the hypothermia protocols) can confound the examination and single measurements of neuron specific enolase (NSE) can be deceiving. Extending the period of evaluation is advisable in patients who remain comatose after cardiac arrest treated with hypothermia.”
Dr. Rabinstein and colleagues evaluated the accuracy of prognostic indicators of neurologic outcome in 192 patients after cardiac arrest. One hundred three of these patients were treated with hypothermia.
In-hospital mortality was 44% (45/103) among hypothermic patients and 75% (67/89) among patients not treated with hypothermia.
No hypothermic or nonhypothermic patients who had absent pupillary light reflex, absent corneal reflexes, or early myoclonic status survived to hospital discharge. Global edema on CT and bilateral absent somatosensory evoked potentials were present in all nonsurvivors and in no survivors of both treatment groups.
NSE levels above 33 ng/mL 1 to 3 days after cardiac arrest had an unacceptably high false-positive rate of 29% for the endpoint of mortality in patients treated with hypothermia, with most survivors achieving favorable functional recovery.
“NSE was the variable exhibiting most differences between the groups, with excellent predictive value in the nonhypothermic group but much less so in the hypothermia group,” Dr. Rabinstein said. “Among hypothermic patients, having a high NSE did not preclude survival with good functional recovery.”
“NSE needs to be used cautiously and in combination with other parameters, especially those derived from physical examination,” Dr. Rabinstein advised. “Serial measurements of NSE might be more informative than single measurements in patients treated with hypothermia.”
Reference:
Predictors of neurologic outcome in hypothermia after cardiac arrest
Ann Neurol 8 November 2010.
