Correlation of Limb Bioimpedance to Echocardiographic Indicators of Congestion in Patients with NYHA Class II/III Heart Failure

Abstract

Purpose: The treatment of heart failure (HF) in the United States is estimated to exceed $30 billion each year and is anticipated to increase to a staggering $70 billion by the year 2030. This makes the management of HF one of the leading challenges Medicare will face in the years to come. Traditional methods to detect impending congestion such as body weight and physical examination findings are often non-specific and lack sensitivity making them inadequate to recognize fluid overload and prevent decompensation. It has been suggested that bioimpedance spectroscopy (BIS) can be used as a surrogate marker for detecting fluid overload and therefore, serve as an adjunct to clinical exam findings. Methods: This study examines the relationship between a BIS device and echocardiographic parameters associated with volume overload with same day measurements in the first 8 patients with NYHA Class II/III HF on an IRB approved protocol. Each patient was followed 3 times a week for 4 weeks within the hospital outpatient setting. At each visit BIS measures were recorded for whole body as well as arms and legs. Additionally, signs and symptoms, weight and echocardiograph findings were all recorded. Results: Correlations of BIS measurements with echo parameters were performed. The leg impedance measurement correlated strongly with echo findings; inferior vena cava (IVC) size (p=0.001), right atrial pressure (RAP) (p<0.001), and pulmonary artery systolic pressure (PAS) measurements (p<0.001). Conclusion: Preliminary findings demonstrated excellent correlations with BIS measurements and IVC size, right atrial pressure and pulmonary artery systolic pressure measurements which suggest a possible alternative method to detect fluid overload despite the small sample size. Trending a patient's impedance using the SOZO device at home or the practitioner's office may assist clinicians in providing more accurate, individualized HF care.