Effects of combined superoxide dismutase and deferoxamine on recovery of brainstem auditory evoked potentials and EEG after asphyxial cardiac arrest in dogs.

In a randomized study in 23 dogs, we tested the following anti-free radical combination therapy, administered at the beginning of CPR, following apnea-induced cardiac arrest of 7 min: a) ventilation with 100% nitrogen for 30 s to allow the delivery of therapy before oxygen; b) superoxide dismutase (10 mg/kg i.a. followed by 10 mg/kg i.v. over 1 h) to scavenge the superoxide anion radical; and c) deferoxamine (20 mg/kg i.v. over 1 h) to prevent membrane lipid peroxidation. We evaluated the effects of this treatment on the recovery of cardiovascular and cerebral variables short term (6 h) after resuscitation. We reported previously that this treatment mitigated the post-arrest cerebral blood flow changes and enhanced the recovery of somatosensory evoked potentials. This is a secondary report from the same study concerning the effects of this treatment on the recovery of brainstem auditory evoked potentials (BAEPs) and EEG. Compared to control (n = 10), the experimental treatment (n = 10) did not exert a clearcut, significant effect on the recovery of BAEP which normalized in both groups at 1 h post-arrest and enhanced the post-arrest recovery of EEG spectra total power by reducing the post-arrest increase in slow frequency bands. However, the relative distribution of EEG frequencies never recovered the pre-arrest pattern in either group, during the 6 h post-arrest observation period. We conclude that the combination treatment tested enhances the recovery but does not normalize cerebral function post-arrest, suggesting that other treatments should also be entertained or that, indeed, such an insult may not be completely ameliorated by any such treatments.