Bioimpedance Spectroscopy Improves Perioperative Fluid Therapy: a Randomized Controlled Trial

Goal of the Study:

Patients who undergo general anesthesia receive intravenous fluid therapy for surgical procedures. However, excessive fluid administration is associated with increased postoperative morbidity and mortality [1]. The present study aimed at determining whether perioperative fluid therapy can be optimized with bioimpedance spectroscopy-based measurements of fluid volume status. Specifically, we tested the hypothesis that significantly more patients under guidance with bioimpedance spectroscopy are normovolemic after gynecologic surgery compared to a control group.

Methods:

In this prospective, randomized controlled trial, we performed pre- and postoperative measurements with the Body Composition Monitor (BCM), a whole body bioimpedance spectroscopy device that measures fluid overload (FO) as a surplus or deficit of normal extracellular volume. In the study group, the amount of intravenous fluid to be administered perioperatively was prescribed based on the preoperative FO result. In the control group, fluid was given according to best clinical practice. We used the Fisher's exact test to compare the number of normovolemic patients within each group and the unpaired Student's t-test to determine differences in pre- and postoperative fluid status between both groups as well as to determine which group showed more improvement towards an ideal fluid status (FO=0 liter).

Results and Discussion:

Sixty-nine patients were enrolled, 35 in the study group and 34 in the control group. Preoperatively, 19 study patients (54 %) and 22 control patients (65%) were normovolemic (FO = 0 ± 1 liter [L]; p = 0.465). Postoperatively, 31 study patients (89 %) and 21 control patients (62%) were normovolemic (p = 0.012). Preoperatively, the study group had a distance to the ideal fluid status (FO = 0 L) of 1.02 ± 0.5 L and the control group of 0.85 ± 0.7 L (p = 0.264). Postoperatively, the study group was 0.6 ± 0.4 L and the control group 0.86 ± 0.7 L apart from FO = 0 L (p = 0.062). The fluid status in the study group changed from pre- to postoperatively (0.4 ± 0.5 L), while the control group's fluid status remained similar (0.0029 ± 0.6 L) which was a significant difference between the two groups (p = 0.002).

Fig. 1

Conclusion:

These results indicate that preoperative BCM measurements improve the patient's postoperative fluid status and should be confirmed in a larger trial.

References:

[1] Holte K, Kehlet H. Fluid Therapy and Surgical Outcomes in Elective Surgery: A Need for Reassessment in Fast-Track Surgery. J Am Coll Surg. 2006;202(6):971–89.