Hydrogen Inhalation is Superior to Mild Hypothermia for Improving Neurological Outcome and Survival in a Cardiac Arrest Model of Spontaneously Hypertensive Rat

Methods: Cardiopulmonary resuscitation was initiated after 4 min of untreated ventricular fibrillation in 40 SHRs. Immediately after successful resuscitation, animals were randomized to be ventilated with 98% oxygen and 2% nitrogen under normothermia (Ctrl), 2% nitrogen under hypothermia (TH), 2% hydrogen under normothermia (H2), or 2% hydrogen under hypothermia (H2+TH) for 2 h. Hypothermia was maintained at 33°C for 2 h. Animals were observed up to 96 h for assessment of survival and neurologic recovery.

Results: No statistical differences in baseline measurements were observed among groups and all the animals were successfully resuscitated. Compared with Ctrl, serum cardiac troponin T measured at 5 h and myocardial damage score measured at 96 h after resuscitation were markedly reduced in H2, TH, and H2+TH groups. Compared with Ctrl and TH, astroglial protein S100 beta measured during the earlier postresuscitation period, and neurological deficit score and neuronal damage score measured at 96 h were considerably lower in both H2 and H2+TH groups. Ninety-six hours survival rates were significantly higher in the H2 (80.0%) and H2+TH (90.0%) groups than TH (30.0%) and to Ctrl (30.0%). Conclusions: Hydrogen inhaling was superior to mild hypothermia for improving neurological outcome and survival in cardiac arrest and resuscitation model of systemic hypertension rats.