Neurophysiologic effects of retrograde cerebral perfusion used for aortic reconstruction.

ABSTRACT

OBJECTIVE: The results of neurophysiologic monitoring using somatosensory evoked potentials (SSEPs) and electroencephalography (EEG) were analyzed to determine if retrograde cerebral perfusion (RCP) supported central nervous system electrical function during surgery that required temporary interruption of antegrade cerebral perfusion (IACP). DESIGN: A prospective, observational study. SETTING: A university hospital. PARTICIPANTS: Fifteen adult patients who underwent aortic reconstruction using RCP and three patients who underwent thoracic aortic operations using hypothermic circulatory arrest without RCP. INTERVENTIONS: SSEPs and EEG were monitored continuously throughout the operation. Regression analysis was performed to determine the factors that affected the rate of decrease in SSEP amplitudes during IACP and the time required for SSEP and EEG activity to recover after antegrade cerebral perfusion (ACP) was restored. MEASUREMENTS AND MAIN RESULTS: The amplitude of SSEPs that were elicited decreased over time after IACP. The mean +/- standard deviation (SD) time required for the brachial plexus (Erb's point), cervicomedullary junction (N13), and brainstem (N18) SSEPs to decrease to 0.5 of their original amplitude after IACP were 30 +/- 2, 19 +/- 2, and 16 +/- 2 minutes, respectively. The rate of decrease in the N18 SSEP amplitude after IACP correlated positively to the fraction of no-flow time (p = 0.01). CONCLUSION: RCP attenuated the rate of decay in SSEP amplitudes during IACP. This suggested that RCP had a measurable physiologic effect on central nervous system function and may increase the time that ACP can be safely interrupted.