Electrical Bioimpedance for Cardiac Output Monitoring and Other Selected Indications

Number: 0472

Policy

  1. Aetna considers cardiac monitoring using electrical bioimpedance devices medically necessary for any of the following uses, when medical history, physical examination, and standard assessment tools provide insufficient information and the treating physician has determined that thoracic electrical bioimpedance hemodynamic data are necessary for appropriate management of the member:

    1. Differentiation of cardiogenic from pulmonary causes of acute dyspnea; or
    2. Evaluation for rejection in persons with a heart transplant as a pre-determined alternative to a myocardial biopsy.  Medical necessity would need to be documented should a biopsy be performed after thoracic electrical bioimpedance; or
    3. Monitoring of response to medication changes in treatment of drug-resistant hypertension; or
    4. Optimization of atrio-ventricular (AV) interval for member with AV sequential cardiac pacemakers; or
    5. Optimization of fluid management in persons with congestive heart failure (CHF); or
    6. Outpatient monitoring of continuous inotropic therapy for persons with terminal CHF.

  2. Aetna considers cardiac monitoring using electrical bioimpedance devices experimental and investigational for any other indications because of insufficient evidence of safety and effectiveness, including the following uses:

    1. Monitoring in congenital heart disease surgery; or
    2. Monitoring of persons during orthotopic liver transplantation; or 
    3. Monitoring of persons on a cardiopulmonary bypass machine as these devices do not render accurate measurements in this situation; or
    4. Monitoring of persons who have ischemic heart disease, but without overt cardiac failure, edema or arrhythmias; or
    5. Monitoring of persons with minute ventilation sensor function pacemakers as the device may adversely affect the functioning of this type of pacemaker; or
    6. Monitoring of persons with proven or suspected disease involving severe regurgitation of the aorta as these devices have not been proven to provide reliable measurements in this situation.
  3. Aetna considers the use of electrical bioimpedance devices for lung capacity screening experimental and investigational because the effectiveness of this approach has not been established.

For bioimpedance for lymphedema, see CPB 0069 - Lymphedema. For bioimpedance for obesity management, see CPB 0039 - Weight Reduction Medications and Programs.

Background

This policy is consistent with the Centers for Medicare & Medicaid Services (CMS), coverage guidelines on measurement of cardiac output (CO) with electrical bioimpedance.

Hemodynamic measurements of CO using thoracic electrical bioimpedance (TEB) devices, a form of plethysmography, relate change in thoracic electrical conductivity to changes in thoracic aortic blood volume and blood flow.  This form of impedance cardiography has been proposed as a simple and readily reproducible non-invasive technique for the determination of CO, specifically, stroke volume, contractility, systemic vascular resistance and thoracic fluid content.  Proponents claim that TEB can measure CO with the same clinical accuracy as either the Fick or thermodilution (TD) technique and that it offers the potential for sequential measurements of CO in patients for whom invasive measurements are impractical or contraindicated.  In addition, TEB can determine CO on a beat-to-beat basis or a predetermined intermittent frequency, which may, if required, permit a more rapid intervention than techniques using time-averaged data.  Its modest gain in popularity as a clinical technique appears to be related to its suggested usefulness as a monitor to detect changes in CO within individual subjects as an alternative to invasive techniques, especially when serial measurements are required.

Currently, there are 2 Food and Drug Administration-approved electrical bioimpedance devices in the marketplace: Bio Z® (Cardiodynamics, Inc.), and TEBCO (Thoracic Electrical Bioimpedance Cardiac Output, Hemo Sapiens, Inc.).

Gujjar and colleagues (2010) compared CO measured by TEB with that measured by multi-gated radionuclide equilibrium cardiography (RNEC).  Studies on CO were carried out sequentially at a single sitting by TEB and RNEC methods among patients with cardiac symptoms referred for radionuclide study as part of their evaluation.  Thoracic electrical bioimpedance-CO was measured by placing 2 pairs of electrodes on either side of neck and 2 other pairs on either side of the lower chest.  Stroke volume was estimated from the sequential changes in TEB induced by rhythmic aortic blood flow, using Kubicek equation; RNEC-CO was measured by intravenous injection of radio-active technitium-tagged red blood cells followed by electrocardiography-gated blood pool imaging over the chest (multiple-gated acquisition study).  Bland-Altman analysis was used to compare the measurements.  A total of 32 subjects with proven or suspected ischemic heart disease, but without overt cardiac failure, edema or arrhythmias were studied (male:female ratio was 26:6; mean age of 48 +/- 12 years).  The mean TEB-CO was 3.54 +/- 1.052 L/min and mean RNEC-CO was 3.907 +/- 0.952 L/min.  Correlation coefficient (r) for these measurements was 0.67 (p < 0.01), with bias: -0.421 L/min; precision: 1.557 L/min; and percentage error of measurement: 42.35 %.  The authors concluded that this study found a moderate correlation between TEB and RNEC methods of CO measurement.  They stated that further studies are needed to examine the relative utility of TEB in comparison with RNEC as well as other methods of CO measurement before considering its use in patients with ischemic heart disease.

Taylor et al (2011) evaluated the measurement of CO using continuous electrical bioimpedance cardiography (Physioflow; Neumedx, Philadelphia, PA) (CO(PF)) with a simultaneous direct Fick measurement (CO(FICK)) in children with congenital heart disease.  The Physioflow measured continuous real time CO in 15-second epochs and simultaneous measurement of CO by direct Fick (with mass spectrometry to assess VO(2)) were acquired.  A total fo 65 patients were recruited, and data from 56 (25 males) were adequate for analysis.  The median age at study was 3.5 years (range of 0.4 to 16.6 years), and the median body surface area was 0.62 m(2) (range of 0.31 to 1.71).  There were 25 of 56 (45 %) with uni-ventricular physiology.  A total of 19,228 Physioflow data points were available for the analysis of which 14,569 (76 %) were valid; 96 % of the invalid measurements were identified as artifacts by the device.  The average cardiac index of valid measurements was 3.09 +/- 0.72 L/min/m(2).  Compared with the Fick CO, the mean bias was -0.09 L/min, but the 95 % limits of agreement were -3.20 to +3.01 L/min/m(2).  Consequently, only 20 of 56 (36 %) of measurements were within 20 %, and 31 of 56 (55 %) of measurements were within 30 % of each other.  The authors concluded that compared with measurements made by direct Fick, CO measured using the Physioflow device was unreliable in anesthetized children with congenital heart disease.

Cardiac Monitoring Using Electrical Bioimpedance Devices During Orthotopic Liver Transplantation

Magliocca and colleagues (2018) noted that orthotopic liver transplantation (OLT) is characterized by significant intra-operative hemodynamic variability.  Accurate and real-time CO monitoring aids clinical decision-making during OLT.  These researchers compared accuracy, precision, and trending ability of CO estimation obtained non-invasively using pulse wave transit time (estimated continuous CO [esCCO; Nihon Kohden, Tokyo, Japan]) or thoracic bioimpedance (ICON; Osypka Medical GmbH, Berlin, Germany) to thermodilution CO (TDCO) measured with a pulmonary artery catheter.  A total of 19 patients undergoing OLT were enrolled; CO measurements were collected with esCCO, ICON, and thermodilution at 5 time points: (T1) pulmonary artery catheter insertion; (T2) surgical incision; (T3) portal reperfusion; (T4) hepatic arterial reperfusion; and (T5) abdominal closure.  The results were analyzed with Bland-Altman plot, percentage error (the percentage of the difference between the CO estimated with the non-invasive monitoring device and CO measured with the thermodilution technique), 4-quadrant plot with concordance rate (the percentage of the total number of points in the I and III quadrant of the 4-quadrant plot), and concordance correlation coefficient (a measure of how well the pairs of observations deviate from the 45-degree line of perfect agreement).  Although TDCO increased at T3 to T5, both esCCO and ICON failed to track the changes of CO with sufficient accuracy and precision.  The mean bias of esCCO and ICON compared to TDCO were -2.0 L/min (SD, ± 2.7 L/min) and -3.3 L/min (SD, ± 2.8 L/min), respectively.  The percentage error was 69 % for esCCO and 77 % for ICON.  The concordance correlation coefficient was 0.653 (95 % confidence interval [CI]: 0.283 to 0.853) for esCCO and 0.310 (95 % CI: -0.167 to 0.669) for ICON.  Nonetheless, esCCO and ICON exhibited reasonable trending ability of TDCO (concordance rate: 95 % [95 % CI: 88 to 100] and 100 % [95 % CI: 93 to 100]), respectively.  The mean bias was correlated with systemic vascular resistance (SVR) and arterial elastance (Ea) for esCCO (SVR, r = 0.610, 95 % CI: 0.216 to 0.833, p < 0.0001; Ea, r = 0.692, 95 % CI: 0.347 to 0.872; p < 0.0001) and ICON (SVR, r = 0.573, 95 % CI: 0.161 to 0.815, p < 0.0001; Ea, r = 0.612, 95 % CI: 0.219 to 0.834, p < 0.0001).  The authors concluded that non-invasive CO estimation with esCCO and ICON exhibited limited accuracy and precision, despite with reasonable trending ability, when compared to TDCO, during OLT.  These investigators stated that inaccuracy of esCCO and ICON is especially large when SVR and Ea were decreased during the neo-hepatic phase.  They stated that further refinement of the technology is desirable before non-invasive techniques could replace TDCO during OLT.

Electrical Bioimpedance Devices for Lung Capacity Screening

Pino and colleagues (2019) described the development and implementation at a prototype level of a wireless, low-cost system for the measurement of the electrical bioimpedance of the chest with 2 channels using the AD5933 in a bi-polar electrode configuration to measure lung volume variation.  A total of 15 volunteers were measured with the prototype, and the acquired signal presented the phases of the respiratory cycle, useful for the breathing rate calculation and for possible screening applications (e.g., lung capacity).

Segmental Bioelectrical Impedance Spectroscopy Devices for Body Composition Measurement

Cannon and Choi (2019) stated that whole-body bioelectrical impedance analysis for measuring body composition has been examined; however, its use may not be sensitive enough to changes in the trunk compared to changes in the limbs.  Measuring individual body segments could address this issue.  These researchers designed a segmental bioelectrical impedance spectroscopy device (SBISD) for body composition measurement and a prototype was implemented.  Compensation was performed to adjust the measured values to correct for a phase difference at high frequencies and to counteract the hook effect when measuring the human body.  The SBISD was used to measure 5 subjects and was compared against 3 existing analyzers.  For most segmental measurements, the SBISD was within 10 % of the R0 and R∞ values determined with a Bodystat Multiscan 5000 and an Impedimed SFB7.  The impedance values from the 3rd reference device, a Seca 514, differed significantly due to its 8-electrode measuring technique, meaning impedance measurements could not be compared directly.  These researchers stated that it is suggested that future work be performed to address the issues in measuring the trunk.  This might be addressed by increasing the number of current injection sites to increase the number of current paths so that the different areas with different makeups could be addressed.  With the current measuring part of the SBISD validated, further components could be focused on, like signal generation and data acquisition, to create a stand-alone device.

Table: CPT Codes / HCPCS Codes / ICD-10 Codes
Code Code Description

Information in the [brackets] below has been added for clarification purposes.   Codes requiring a 7th character are represented by "+":

CPT codes covered if selection criteria are met:
93701 Bioimpedance, thoracic, electrical

Other CPT codes related to the CPB:
47135 Liver allotransplantation, orthotopic, partial or whole, from cadaver or living donor, any age

ICD-10 codes covered if selection criteria are met:
I09.81 Rheumatic heart failure
I10 - I16.2 Hypertensive diseases
I50.1 - I50.9 Heart failure
R06.00- R06.09 Dyspnea [acute]
T86.20 - T86.39 Complications of heart transplant
Z45.010 Encounter for checking and testing of cardiac pacemaker pulse generator [battery]
Z45.018 Encounter for adjustment and management of other part of cardiac pacemaker
Z48.21 Encounter for aftercare following heart transplant
Z48.280 Encounter for aftercare following heart-lung transplant
Z94.1 Heart transplant status
Z94.3 Heart and lungs transplant status
Z95.0 Presence of cardiac pacemaker

ICD-10 codes not covered for indications listed in the CPB (not all-inclusive):
I20.0 - I25.9 Ischemic heart disease [without overt cardiac failure, edema, or arrhythmias]
I35.0 - I35.9 Nonrheumatic aortic valve disorders
Q20.0 - Q26.9 Bulbus cordis anomalies and anomalies of cardiac septal closure, other congenital anomalies of heart, other congenital anomalies of circulatory system, and anomalies of great veins [monitoring congenital heart disease surgery]
Z13.83 Encounter for screening for respiratory disorder NEC [lung capacity screening]

The above policy is based on the following references:

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