Background
Oxygen plays a pivotal role in
cardiopulmonary resuscitation (
CPR) and postresuscitation intervention for
cardiac arrest. However, the optimal method to reoxygenate patients has not been determined. This study investigated the effect of timing of hyperoxygenation on neurological outcomes in
cardiac arrest/
CPR rats treated with
targeted temperature management. Methods and Results After induction of
ventricular fibrillation, male Sprague-Dawley rats were randomized into 4 groups (n=16/group): (1) normoxic control; (2) O2_
CPR, ventilated with 100% O2 during
CPR; (3) O2_CPR+postresuscitation, ventilated with 100% O2 during
CPR and the first 3 hours of postresuscitation; and (4) O2_postresuscitation, ventilated with 100% O2 during the first 3 hours of postresuscitation.
Targeted temperature management was induced immediately after
resuscitation and maintained for 3 hours in all animals. Postresuscitation hemodynamics, neurological recovery, and pathological analysis were assessed. Brain tissues of additional rats undergoing the same experimental procedure were harvested for ELISA-based quantification assays of oxidative stress-related
biomarkers and compared with the
sham-operated rats (n=6/group). We found that postresuscitation mean arterial pressure and quantitative electroencephalogram activity were significantly increased, whereas astroglial
protein S100B, degenerated neurons, oxidative stress-related
biomarkers, and
neurologic deficit scores were significantly reduced in the O2_CPR+postresuscitation group compared with the normoxic control group. In addition, 96-hour survival rates were significantly improved in all of the hyperoxygenation groups. Conclusions In this
cardiac arrest/
CPR rat model, hyperoxygenation coupled with
targeted temperature management attenuates
ischemia/reperfusion-induced
injuries and improves survival rates. The beneficial effects of high-concentration
oxygen are timing and duration dependent. Hyperoxygenation commenced with
CPR, which improves outcomes when administered during
hypothermia.