Change in bioelectrical impedance following laparoscopic and open abdominal surgery

The effect of surgery, and in particular, the relative effects of open and laparoscopic abdominal surgery on whole body bioelectrical impedance (BI) has been investigated. Repeated measurements of BI were performed over a 60 h period in 12 patients undergoing laparoscopic surgery (group A) and in 12 patients undergoing elective open abdominal surgery for benign conditions (group B). Control measurements were performed upon 4 healthy adult subjects over the same time period. Attempts were made to relate postoperative changes in BI in group A and group B to changes in net postoperative fluid balance. The postoperative disturbance in BI was significantly greater in group B than group A (P < 0.001 Mann-Whitney-U test) and differed significantly from the minor fluctuations of BI observed in the control group (P < 0.001 Mann-Whitney-U test). The fluctuations in BI observed after laparoscopic surgery were not significantly greater than those seen in the control group (P = 0.1 Mann- Whitney U test). Changes in BI in both group A and B did not correlate with changes in net postoperative fluid balance, which suggests that the effect of surgery upon BI was related to changes of body water distribution rather than changes in total body water volume.