Purpose: In order to avoid neurological complications related to cerebral malperfusion in aortic surgery, we have established an integrated three-stage monitoring system consisting of near-infrared spectroscopy (NIRS), orbital Doppler, and transesophageal echocardiography (TEE). Purpose of this study was to evaluate it for reducing neurological complications.
Methods: Efficacy of this monitor was retrospectively examined in 254 cases of aortic surgery, including 131 and 123 cases in the pre- and post-monitor period, respectively. When the regional oxygen saturation dropped below 60%, blood flow in the central retinal artery was examined with orbital Doppler. If cerebral malperfusion was present, the arch branches were visualized with TEE to identify the cause of malperfusion. Problem-oriented strategy was made based on the TEE findings and the results were immediately assessed by NIRS and orbital Doppler. Neurological events including cerebral infarction and transient dysfunction (convulsion, delirium, and anisocoria) were picked up from the medical records.
Results: After the monitor was introduced, incidence of transient neurological events significantly decreased from 22.0% to 9.6% (p=0.0107), while that of cerebral infarction decreased from 10.7% to 5.3% (not significant: p=0.1609). On univariate and multivariate analyses, operation time (odd's ratio [OR]: 1.006 per minute, p=0.0002) was an independent predictors and use of integrated monitor was a protective factor (OR:0.206, p=0.0003) for transient neurological events.
Conclusions: As a part of this monitoring system, ultrasonography plays an important role for reducing neurological complications in aortic surgery by confirming cerebral malperfusion and identifying its mechanism, thus facilitating an efficient, problem-oriented solution.