Effects of hypothermic and normothermic cardiopulmonary bypass on brain oxygenation

Background. In this study, we assessed the effects of normothermia and hypo thermia during cardiopulmonary bypass (CPB) both on internal jugular venous oxygen saturation (SjvO(2)) and the regional cerebral oxygenation state (r SO(2)) estimated by near infrared spectroscopy (NIRS). Methods. Thirty patients scheduled for elective coronary artery bypass graf t surgery (CABG) were randomly divided into two groups. Group 1 (n = 15) un derwent surgery for normothermic (>35 degrees C) CPB, and group 2 (n 15) un derwent surgery for hypothermic (30 degrees C) CPB, and alpha-stat regulati on was applied. A 4.0-French fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to continuously monitor the SjvO( 2) value. To estimate the rSO(2) state, a spectrophotometer probe was attac hed to the mid-forehead. SjvO(2) and rSO(2) values were then collected simu ltaneously using a computer. Results. Neither the cerebral desaturation time (duration during SjvO(2) va lue below 50%), nor the ratio of the cerebral desaturation time to the tota l CPB time significantly differed (normothermic group: 18 +/- 6 min, 15 +/- 6%; hypothermic group: 17 +/- 6 min, 13 +/- 6%, respectively). The rSO(2) value in the normothermic group decreased during the CPB period compared wi th the pre-CFB period. The rSO(2) value in the hypothermic group did not ch ange throughout the perioperative period. Conclusions. These findings suggest that near infrared spectroscopy might b e sensitive enough to detect subtle changes in regional cerebral oxygenatio n. (C) 1999 by The Society of Thoracic Surgeons.