Effect of skin in temperature on multi-frequency bioelectrical
impedance analysis.
Gudivaka, Rani, Dale Schoeller, and Robert F Kushner.
The University of Chicago, Department of Medicine, MC4080, Clinical
Nutrition Research Unit, 5854 South Maryland Avenue, Chicago,
Illinois 60637
APStracts 3:0180A, 1996.
This study assessed the effects of changes in skin temperature on
multi-frequency bioimpedance analysis (MF-BIA) and on the prediction
of body water compartments. Skin temperature (baseline 29.3 +/- 2.1
degrees C) of six healthy adults was raised over 50 min. to 35.8 +/-
0.6 degrees C followed by cooling for 20 min. to 26.9 +/-1.3 degrees
C using an external heating and cooling blanket. MF-BIA was measured
at both distal (conventional) and proximal electrode placements. Both
distal and proximal impedance varied inversely with a change in skin
temperature across all frequencies (5-500 kHz). The change in
proximal impedance per degree change in skin surface temperature was
about 60% of distal impedance. The change in measured impedance at 50
kHz erroneously increased predicted total body water (TBW) by 2.6 +/-
0.9 L (p < 0.001) and underpredicted fat mass by 3.3 +/- 1.3 kg
(p < 0.0001). Computer modeling of the MF-BIA data indicated
changes in predicted water compartments with temperature
modifications, however the ratio of extracellular water (ECW) to TBW
did not significantly change (p < 0.4). This change in impedance
was not due to a change in the movement of water of the ECW
compartment, and thus probably represents a change in cutaneous
impedance of the skin. Controlled ambient and skin temperature should
be included in the standardization of BIA measurements. The error in
predicted TBW is < 1% within an ambient temperature range of
22.3 degrees C to 27.7 degrees C (72.1 degrees F to 81.9 degrees F).
Received 10 August 1995; accepted in final form 22 March 1996.
APS Manuscript Number A873-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96