Assessement of Change in Body Water By Multiple Frequency Bioelectrical Impedance in Patients Undergoing Cardiopulmonary Bypass

Objective: To evaluate the relationship between changes in body bioelectrical impedance (BI) at 1, 50, 100 kHz and fluid balance, as an index of body water changes, in patients undergoing cardiopulmonary bypass.
Design: Descriptive, correlative.
Setting: Intensive Care Unit of a cardiac center Patients: Twenty male patients, before and after elective coronary artery bypass graft surgery with cardiopulmonary bypass.
Interventions: None.
Measurements: Whole body bioelectrical impedance using multiple frequency bioelectrical impedance (Dietosystem, Italy) at multiple frequencies (1, 50, 100 kHz) was conducted preoperatively and three times during the 24 hour postoperative period. The volume of body water compartment was calculated using Guricci’s formula. The calculated fluid balances uncorrected for insensible water losses were measured from fluid intake and output.
Findings: In 24 hours after surgery calculated total body water (TBW), extracellular water (ECW), and intracellular water (ICW) increased by 16.0%, 20.7%, and 13.0%, respectively, but the values were within desirable ranges. There was no correlation between TBW changes measured by MFBIA and calculated fluid balance.
Conclusions: The current study indicates that changes of body water compartment occur during 24 hours after CABG. Calculated ICW increases within 24 hours after CABG.