[Change in the volume of extra cellular fluid in coronary artery bypass grafting (CABG); comparison between off-pump and on-pump CABG].

During the perioperative period for off-pump coronary artery bypass surgery (OPCAB) and on-pump coronary artery bypass surgery (on-pump CABG), the volume of extra cellular fluid (ECF) was measured. The subjects were elective adult coronary artery bypass surgery cases, consisting of 13 OPCAB cases and 7 on-pump CABG cases. The ECF volume was measured the day before surgery, immediately after surgery, and 2, 4, 6, 8, 12, 24 and 48 hours after surgery, with a bioimpedance analyzer (XITRON 4000 C). ECF volume variation was defined as the difference from the preoperative value divided by body weight, and was expressed in %BW. At the same time, respiratory-index and leukocyte count were measured. The maximum postoperative ECF volume was 3.13 +/- 2.6 %BW in the OPCAB group and 5.36 +/- 2.0 %BW in the on-pump CABG group, that is, significantly higher in the on-pump CABG group. The ECF volume started to increase in the on-pump CABG group immediately after surgery (4.38 +/- 1.8 %BW in the on-pump CABG group and 2.07 +/- 2.4 %BW in the OPCAB group), reaching its peak 6 hours after surgery in the on-pump CABG group and 4 hours after surgery in the OPCAB group. Thereafter, the volume gradually decreased, and 48 hours after surgery the volume decreased in the OPCAB group to 0.064 +/- 1.5 %BW, or to about the same value as the preoperative value, whereas in the on-pump CABG group the volume remained high: 1.9 +/- 2.9 % BW. There was no significant difference between the 2 groups in the change in respiratory-index. The leukocyte count remained significantly higher in the on-pump CABG group. The ECF volume was measured by the bioimpedance measuring method. This is a useful method of measuring the volume non-invasively and continuously. In the OPCAB group, the increase in postoperative ECF volume was less, and recovery to the preoperative level was faster than in the on-pump CABG group.