Lower leg electrical impedance after distal bypass surgery

Electrical impedance was determined in 13 patients following distal bypass surgery to evaluate lower leg oedema as reflected by its circumference. Tissue injury was assessed by the plasma concentration of muscle enzymes. After surgery, the volume of the control lower leg increased from 1250 (816-2373) to 1384 (874-2345) ml (median and range; P <0.05), where the impedance did not change significantly from 140 (92-181) ohms. The volume of the operated leg increased more [from 1129 (824-2373) to 1600 (1090-2837) ml], and the decrease in electrical impedance was also pronounced [137 (125-169) to 83 (69-104) ohms (P <0.001)]. Tissue injury after surgery was indicated by an increase in total creatine kinase (n = 17) and MB isoenzyme of creatine kinase (n = 8) (P <0.05). Myoglobin (n = 8) had increased already during surgery (P <0.05), whereas there was no significant change in the plasma concentration of troponin I (n = 8). In conclusion, tissue injury was reflected by increases in muscle enzymes in plasma. We found an inverse correlation between lower leg electrical impedance and volume, but the deviation in electrical impedance was approximately twice that of the leg volume. Electrical impedance appears to be a useful method for the evaluation of lower leg oedema after distal bypass surgery.