Objective: To review the principles and physics of bioelectrical impedance analysis (BIA) and its current use in human and veterinary medicine.
Data sources: Research for this manuscript included current human and veterinary literature.
Human-based studies: Human studies of BIA and multifrequency bioelectrical impedance analysis (MFBIA) have resulted in a considerable amount of controversy about the capability of BIA and MFBIA to accurately assess exact fluid volume and distribution. The recent emphasis on point-of-care monitoring has resulted in the use of BIA and MFBIA to evaluate the rapid changes in fluid distribution that can occur with trauma and various disease states.
Veterinary-based studies: The use of BIA and MFBIA has been limited in veterinary medicine. However, studies in domestic and laboratory animals have shown good correlation with the isotope dilution method. The effectiveness of BIA/MFBIA in monitoring the critically ill veterinary patient has not yet been evaluated.
Conclusion: BIA and MFBIA have been used to evaluate a variety of biological parameters such as nutritional status, cardiac output, and intracellular and extracellular fluid volumes. Recent studies using BIA and MFBIA to evaluate fluid compartmentalization and shifts in critically ill human patients have shown promising results. BIA and MFBIA provide immediate results that may aid in the assessment of a patient's clinical progress and response to therapy.