BEDSIDE DETERMINATION OF FLUID ACCUMULATION AFTER CARDIAC-SURGERY USING SEGMENTAL BIOELECTRICAL-IMPEDANCE

Objectives: Bioelectrical impedance analysis (BIA) is based on the phy sical property of tissues to conduct electrical currents, impedance be ing inversely related to tissue fluid content. At high frequency, the electrical current flows across both intracellular and extracellular p athways, making the assessment of fat-free mass possible while a low-f requency current flows through the extracellular space. Similarly, seg mental BIA may be used to assess seg mental body fluid repartition. Th e aim of this study was to assess fluid accumulation after cardiac sur gery by multiple frequency segmental BIA, Design: Observational, clini cal study. Setting: A 17-bed, surgical intensive care unit in a univer sity hospital. Patients: Twenty-six patients before and after open-hea rt surgery with cardiopulmonary bypass, Interventions: None. Measureme nts and Main Results: After surgery, fluid accumulation resulted in a decrease in whole body and segmental bioelectrical impedance in the ar m and in the trunk. There was a good correlation between the fluid acc umulation measured by fluid balance and by whole body or segmental imp edance changes. The major part (71%) of fluid accumulation occurred in the trunk. Multiple frequency measurements did not indicate a fluid s hift between the intra-and extracellular compartments, Conclusion: Car diac surgery produced a significant decrease in segmental trunk BIA, r eflecting fluid accumulation at the trunk It!vel.