Monitoring of regional cerebral oxygenation by near-infrared spectroscopy during continuous retrograde cerebral perfusion for aortic arch surgery

Objective: To assess the value of monitoring of regional cerebral oxygen sa turation (rSO(2)) during aortic arch surgery using continuous retrograde ce rebral perfusion (CRCP) in conjunction with profound hypothermic circulator y arrest (HCA). Methods: The rSO(2) of 12 consecutive patients was monitore d non-invasively using near-infrared spectroscopy (NIRS) and the data were analyzed statistically. Results: The mean duration of HCA with CRCP was 62 +/- 14.1 min. The mean CRCP flow rate was 226 +/- 163 ml/min. Surgical outc omes were favorable with only a single hospital death (8.3%). However, the rSO(2) decreased gradually in ail patients during HCA, even combined with C RCP, and fell to 46 +/- 8.7% on average. It did not change so greatly befor e HCA and returned finally to its initial level at the end of re-warming. O nly one patient developed a permanent neurologic deficit; this patient show ed the greatest decrease of rSO(2) from 56% to 29% after the longest HCA of 88 min. Two parameters, End-rSO(2) (the ratio of post- to pre-HCA rSO(2)) and Delta-rSO(2) (the rate of decrease from pre-to post-HCA rSO(2)) were ob tained since the initial values of rSO(2) before surgery differed. There we re linear correlations between the CRCP flow rate and each of these two par ameters. A multiple regression analysis also revealed a linear equation rel ating the parameters, which allowed prediction of the safe duration of HCA in different conditions of CRCP and a more favorable adjustment of the CRCP condition in each patient. Conclusions: The study suggests that the combin ation of HCA and CRCP has a limit of safe duration in spite of its potentia l usefulness for brain protection, and that rSO(2) monitored by NIRS is use ful in testing for adequate brain protection. It is hoped that monitoring o f rSO(2) can facilitate prediction of the safe duration of HCA with CRCP an d a more favorable adjustment of CRCP. (C) 1998 Elsevier Science B.V. All r ights reserved.