bioimpedance vector analysis (BIVA)

^[1]^[2]

Indications

non-invasive, quick & inexpensive technique to estimate body composition, including total body water
- evaluation of heart failure^[1]
- assessment of risk for contrast nephropathy^[2]

fat-free tissues & fluids are good conductors, while bone & fat tissues are poor conductors
resistance is inversely related to the total body water

measures the opposition of body tissues to the flow of an alternating current of 800 micro Amps at an operating frequency of 50 kHz (bioelectrical impedance
performed with a portable battery-operated device
subject must be supine with inferior limbs at 45 degrees & superior limbs abducted at 30 degrees to avoid skin contacts with the trunk and with stretcher
4 cutaneous electrodes, 2 on wrist & 2 on ipsilateral ankle, are applied with an inter-electrode distance of at least 5 cm to prevent interaction between electrodes
bioelectrical impedance is measured in about 30 sec
reference values are adjusted for patient's age, BMI, gender & height
results are plotted resistance vs reactance* to provide a vector proportional to total body water

* reactance (Xc) is considered proportional to body mass

↑ ^1.0 ^1.1 Di Somma S, Vetrone F, Maisel AS Bioimpedance Vector Analysis (BIVA) for Diagnosis and Management of Acute Heart Failure. Curr Emerg Hosp Med Rep (2014) 2: 104 https://link.springer.com/article/10.1007/s40138-014-0043-9
↑ ^2.0 ^2.1 Maioli M et al. Bioimpedance-guided hydration for the prevention of contrast- induced kidney injury: The HYDRA Study. J Am Coll Cardiol 2018 Jun 26; 71:2880. PMID: https://www.ncbi.nlm.nih.gov/pubmed/29929610
Brar SS. Protocol-driven CI-AKI prevention in the cath lab. J Am Coll Cardiol 2018 Jun 26; 71:2890. PMID: https://www.ncbi.nlm.nih.gov/pubmed/29929611