Abstract:

Objective To investigate the application of near-infrared spectroscopy and bispectral index (BIS) in monitoring of cerebral oxygen balance during surgery with deep hypothermic circulatory arrest （DHCA）. Methods Twelve patients undergoing aortic reconstructive surgery with DHCA were included in this study. BIS, tissue oxygenation index (TOI) and mean arterial pressure (MAP) were recorded before anesthesia (T0), 30 min after anesthesia (T1), after aortic occlusion and cardiac arrest (T2), 5 min after circulatory arrest (T3), 30 min after circulatory arrest (T4), 10 min after circulatory restoration (T5), cardiac rebeating (T6), 10 min after extracorporeal circulation withdrawl (T7), 30 min after extracorporeal circulation withdrawl (T8) and at the end of operation (T9), mixed venous oxygen saturation （SvO₂）was detected at the time points of T1 to T9, and postoperative consciousness state was observed. The relationship between TOI and MAP, BIS and SvO2 was analysed. Results In 8 of all the 12 patients, BIS varied from 20 to 50 and TOI changed from 55% to 75% during anesthesia, and BIS was 0 and TOI maintained above 58% during circulatory arrest. All these 8 patients came to consciousness on the first day after surgery. Another 2 patients who experienced relative massive hemorrhage and TOI lower than 55% for more than 30 min during operation did not regain consciousness 5 d after operation. One patient with a history of TOI less than 55% (for less than 10 min) was re-sedated due to restlessness on the first day after operation, and came to consciousness on the following day. The other patient died 4 h after operation. Correlation analysis revealed that TOI had no linear correlation with MAP and BIS, and TOI was significantly positively related to SvO₂ (r=0.581 9, P<0.05). Conclusion Near-infrared spectroscopy combined with BIS can be used for dynamic monitoring of cerebral oxygen balance during surgery with DHCA and comprehensive evaluation of cerebral protection during operation, and TOI may be significantly positively related to SvO₂.

Key words: deep hypothermic circulatory arrest, near-infrared spectroscopy, bispectral index, tissue oxygenation index, complications