Background:
Mitochondrial dysfunction contributes to cardiac arrest induced brain injury and has been a target for neuroprotective therapies. An emerging concept suggests that hyperactivation of neuronal mitochondria following resuscitation results in hyperpolarization of the mitochondrial membrane during reperfusion, which drives generation of excess reactive oxygen species. Previous studies from our group demonstrated that limiting mitochondrial hyperactivity by non-invasively modulating mitochondrial function with specific near infrared light (NIR) wavelengths can reduce brain injury in small animal models of global and focal ischemia.
Hypothesis:
Inhibitory wavelengths of NIR will reduce neuronal injury and improve neurocognitive outcome in a clinically relevant swine model of cardiac arrest.
Methods:
Twenty-eight male and female adult swine were enrolled (3 groups: Sham, CA/CPR, and CA/CPR + NIR). Cardiac arrest (8 minutes) was induced with a ventricular pacing wire and followed by manual CPR with defibrillation and epinephrine every 30 seconds until return of spontaneous circulation (ROSC), 2 of the 20 swine that underwent CA did not achieve ROSC and were not enrolled. Treatment groups were randomized prior to arrest and blinded to the CPR team. Treatment was applied at onset of ROSC by irradiating the scalp with 750 nm and 950 nm LEDs (5W) for 2 hours.
Results:
Sham-operated animals all survived (8/8), whereas 22% of untreated animals subjected to cardiac arrest died within 45 min of ROSC (CA/CPR, n= 7/9). All swine treated with NIR survived the duration of the study (CA/CPR + NIR, n=9/9). Four days following cardiac arrest, neurological deficit score was improved in the NIR treatment group (50 ± 21 CA/CPR vs. 0.8 ± 0.8 CA/CPR + NIR, p < 0.05). Additionally, neuronal death in the CA1/CA3 regions of the hippocampus, assessed by counting surviving neurons with stereology, was attenuated by treatment with NIR (17917 ± 5534 neurons/mm
3
CA/CPR vs. 44655 ± 5637 neurons/mm
3
CA/CPR + NIR, p < 0.05). All data is reported as mean ± SEM.
Conclusions:
These data provide evidence that noninvasive modulation of mitochondria, achieved by transcranial irradiation of the brain with NIR, mitigates post-cardiac arrest brain injury.
Mismatch between Tissue Partial Oxygen Pressure and Near-Infrared Spectroscopy Neuromonitoring of Tissue Respiration in Acute Brain Trauma: The Rationale for Implementing a Multimodal Monitoring Strategy