title: Bioimpedance spectroscopy for assessment of volume status in patients before and after general anaesthesia.
abstract: BACKGROUND
  Technically assisted assessment of volume status before surgery may be useful to direct intraoperative fluid administration. We therefore tested a recently developed whole-body bioimpedance spectroscopy device to determine pre- to postoperative fluid distribution.
  
  
  METHODS
  Using a three-compartment physiologic tissue model, the body composition monitor (BCM, Fresenius Medical Care, Germany) measures total body fluid volume, extracellular volume, intracellular volume and fluid overload as surplus or deficit of 'normal' extracellular volume. BCM-measurements were performed before and after standardized general anaesthesia for gynaecological procedures (laparotomies, laparoscopies and vaginal surgeries). BCM results were blinded to the attending anaesthesiologist and data analysed using the 2-sided, paired Student's t-test and multiple linear regression.
  
  
  RESULTS
  In 71 females aged 45 ± 15 years with body weight 67 ± 13 kg and Duration of anesthesia 154 ± 69 minutes [corrected] duration of anaesthesia 154 ± 68 min, pre- to postoperative fluid overload increased from -0.7 ± 1.1 L to 0.1 ± 1.0 L, corresponding to -5.1 ± 7.5% and 0.8 ± 6.7% of normal extracellular volume, respectively (both p<0.001), after patients had received 1.9 ± 0.9 L intravenous crystalloid fluid. Perioperative urinary excretion was 0.3 ± 0.2 L [corrected]. The increase in extracellular volume was paralleled by an increase in total body fluid volume, while intracellular volume increased only slightly and without reaching statistical significance (p = 0.15). Net perioperative fluid balance (administered fluid volume minus urinary excretion) was significantly associated with change in extracellular volume (r(2) = 0.65), but was not associated with change in intracellular volume (r(2) = 0.01).
  
  
  CONCLUSIONS
  Routine intraoperative fluid administration results in a significant, and clinically meaningful increase in the extracellular compartment. BCM-measurements yielded plausible results and may become useful to guide intraoperative fluid therapy in future studies.
authors.affiliation: Medical University of Vienna, Department of Anaesthesiology and Critical Care Medicine, Vienna, Austria.
authors.forename: Matthäus
authors.initials: M
authors.lastname: Ernstbrunner
authors.affiliation: Medical University of Vienna, Department of Anaesthesiology and Critical Care Medicine, Vienna, Austria.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kostner
authors.affiliation: Medical University of Vienna, Department of Anaesthesiology and Critical Care Medicine, Vienna, Austria.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kimberger
authors.affiliation: Fresenius Medical Care, Bad Homburg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Wabel
authors.affiliation: Medical University of Vienna, Department of Internal Medicine III, Clinical Division of Nephrology & Dialysis, Vienna, Austria.
authors.forename: Marcus
authors.initials: M
authors.lastname: Säemann
authors.affiliation: Medical University of Vienna, Department of Anaesthesiology and Critical Care Medicine, Vienna, Austria.
authors.forename: Klaus
authors.initials: K
authors.lastname: Markstaller
authors.affiliation: Medical University of Vienna, Department of Anaesthesiology and Critical Care Medicine, Vienna, Austria.
authors.forename: Edith
authors.initials: E
authors.lastname: Fleischmann
authors.affiliation: Medical University of Vienna, Department of Anaesthesiology and Critical Care Medicine, Vienna, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Kabon
authors.affiliation: Medical University of Vienna, Department of Anaesthesiology and Critical Care Medicine, Vienna, Austria; Medical University of Vienna, Department of Internal Medicine III, Clinical Division of Nephrology & Dialysis, Vienna, Austria.
authors.forename: Manfred
authors.initials: M
authors.lastname: Hecking
mesh_terms: D000328:Adult; D000368:Aged; D000768:Anesthesia, General; D001823:Body Composition; D001826:Body Fluids / Q000737:chemistry* / Q000378:metabolism; D058266:Dielectric Spectroscopy; D005260:Female; D013509:Gynecologic Surgical Procedures; D006801:Humans; D008875:Middle Aged; D055986:Vital Signs; D055815:Young Adult