The Effect of Reperfusion on Cerebral Activity in Donors after Circulatory Death Following Normothermic Regional Perfusion

Abstract

Purpose To investigate brain activity and intracerebral physiological parameters following no-touch and normothermic regional perfusion (NRP) in donors after circulatory death. Methods The study comprised 16 female pigs of 85 kg. Following anesthesia, five burr holes were placed in the skull targeting the parasagittal cortex bilaterally. To assess cortical brain activity two needles were used to record electroencephalography (EEG) and somatosensory evoked potentials (SSEP). Two probes measuring intracranial pressure and cerebral blood perfusion (CBF), temperature, and oxygen were inserted. Additionally, a microdialysis catheter for metabolic monitoring of lactate, pyruvate, glycerol, and glucose was inserted. The animals were cannulated for the heart-lung machine and baseline measurements were performed before withdrawal from life support. Before NRP, the animals were randomized into two groups: Clamp or non-clamp of the aortic arch vessels. After mechanical asystole, a no-touch period of 8 minutes was observed before the institution of NRP. The animals were weaned from NRP after 30 minutes and subsequently monitored for 3 hours after weaning. Results In the clamp group, flatline EEG and no-SSEPs were recorded after weaning in all pigs. In the non-clamp group, SSEPs were observed after weaning in 6/8 pigs. In all pigs, a peculiar EEG activity of periodic 4-5 Hz complexes, amplitude up to 300 μV, with a repetition interval of one in every 8-60 seconds was recorded. In two pigs, continuous EEG activity was observed alongside the periodic complexes. Additionally, spontaneous respiratory movements were observed in 6/8 pigs in the non-clamp group during a brief pause of ventilation. Preliminary analysis of intracranial measurements of CBF, oxygen, and temperature indicates successful occlusion of the arch vessels in the clamp group and as such cessation of cerebral perfusion. All results await final statistical analysis. Conclusion Some degree of cerebral function returns following circulatory death and resuscitation with NRP and cerebral reperfusion. We observed continuous EEG activity alongside periodic complexes resembling the so-called Nu-complexes thought to originate in the hippocampus. In addition, SSEP response and negative apnea tests suggest that brain stem function returns following NRP with preserved cerebral perfusion.