Neuroprotective effects of the inhalational anesthetics isoflurane and xenon after cardiac arrest in pigs.

OBJECTIVE: Neurologic outcome after cardiopulmonary resuscitation from cardiac arrest carries a poor prognosis and treatment options to ameliorate brain damage are limited.

DESIGN: Report of two protocols investigating the effects of xenon (Xe) and isoflurane (Iso) in a porcine model of prolonged cardiac arrest and subsequent cardiopulmonary resuscitation on functional neurologic outcomes.

SETTING: Prospective, randomized, laboratory animal study.

SUBJECTS: Male domestic pigs (Sus scrofa).

INTERVENTIONS: After successful resuscitation from 8 mins of cardiac arrest and 5 mins of cardiopulmonary resuscitation, pigs were randomized to receive either Xe for 1 or 5 hrs in comparison with untreated controls 1 hr after cardiopulmonary resuscitation (protocol 1) or to receive Iso or Xe in comparison with untreated controls 10 mins after cardiopulmonary resuscitation (protocol 2).

MEASUREMENTS AND MAIN RESULTS: Animals were exposed to an established cognitive function test and gross neurologic performance was assessed using a neurologic deficit score. In protocol 1, Xe administration resulted in improved early cognitive and overall neurologic function, whereas in protocol 2 there was no significant effect on functional performance.

CONCLUSIONS: Although Xe conferred functional neurologic improvement even when treatment was delayed for 1 hr, the early treatment with either Xe or Iso translated to only marginal functional improvement.