PMC8060148_01
SOZO device. As shown, the device is configured to perform bioimpedance spectroscopy (BIS) measurements with the subject in a standing position. Bare hands and feet must be in direct contact with the electrodes (i.e., no shoes, socks, stockings, or gloves), and metallic/electronic items should be removed. BIS measurement and fluid status reporting takes ~30 s.
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F1
Given that the BIS device used in this report (Figure 1) operates while the test subject is sitting or standing without contacting metal and/or electronic objects, use in the intensive care setting is impractical.
Extracellular fluid percentage of total body water; box-and-whisker plots (A), and clinical strata (B). (A) box-and-whisker plots for bioimpedance spectroscopy-derived extracellular fluid percentage of total body water (ECF%TBW) for Healthy Control Subjects (CON-pop, gray plot) and Heart Failure Patients (HF-pop, blue plot). (B) Normal, bottom three CON-pop quartiles; Elevated, bound by CON-pop 3rd quartile and HF-pop 3rd quartile; Fluid Overload, highest HF-pop quartile.
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F3
The ECF%TBW strata shown in Figure 3B are based on population data and should be interpreted in clinical context.
Lower extremity R0 impedance measurements vs. inferior vena cava (IVC) size; left leg (A), right leg (B). Left leg (A) and right leg (B) scatter plots for R0 impedance vs. inferior vena cava (IVC) size for the subgroup of 12 heart failure patients enrolled in the IMPEL clinical study (ClinicalTrials.gov identifier NCT02857231). Right atrial pressure (RAP) categories: RAP1 in gray (<8 mmHg), RAP2 in orange (8-14.99 mmHg), and in blue RAP3 (15 mmHg). R0 impedance is inversely related to extracellular fluid volume. Hence, in both legs, lower impedance values are associated with larger IVC size and higher right atrial pressures. R0, resistance at zero Hertz; IVC, inferior vena cava; RAP, right atrial pressure; cm, centimeter.
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F4
As shown in Figure 4, BIS measurements correlate strongly with ultrasound-measured inferior vena cava size which has been used in clinic to manage diuresis and identify early fluid overload.
Case Study: 87 year-old man with two heart failure readmissions. ECF, extracellular fluid; ICF, intracellular fluid; TBW, total body water; ECF%TBW, extracellular fluid as a percentage of total body water; mg, milligram; po, oral; qd, daily; L, liters; kg, kilograms; BIS, bioimpedance spectroscopy; SNF, skilled nursing facility. The red line at 51% ECF%TBW indicates the transition from elevated fluid volume to fluid overload.
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F5
The case study presented in this report (Figure 5) is intended to provide an example of how BIS-derived fluid volume measures may be used to aid in monitoring patients with HF.