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.

4. Aetna considers the use of electrical bioimpedance devices experimental and investigational for detection and/or prognosis of cancers, and palliative cancer care.

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.

Detection / Prognosis of Cancers and Palliative Cancer Care

Gupta et al (2004) noted that bioelectrical impedance analysis (BIA) is an easy-to-use, non-invasive and reproducible technique to examine changes in body composition and nutritional status.  These investigators examined the prognostic role of phase angle in advanced pancreatic cancer.  They examined a case series of 58 stage-IV pancreatic cancer patients treated at Cancer Treatment Centers of America at Midwestern Regional Medical Center (Zion, IL) between January 2000 and July 2003.  BIA was carried out on all patients using a bioelectrical impedance analyzer that operated at 50-kHz.  The phase angle was calculated as capacitance (Xc)/resistance (R) and expressed in degrees.  The Kaplan-Meier method was used to calculate survival.  Cox proportional hazard models were constructed to examine the prognostic effect of phase angle independent of other clinical and nutritional variables.  The correlations between phase angle and traditional nutritional measures were assessed using Pearson and Spearman coefficients.  Patients with phase angle of less than 5.0 degrees had a median survival time of 6.3  months (95 % CI: 3.5 to 9.2; n = 29), while those with phase angle of greater than 5.0 degrees had a median survival time of 10.2 months (95 % CI: 9.6 to 10.8; n = 29); this difference was statistically significant (p = 0.02).  The authors concluded that the findings of this study showed that phase angle was a strong prognostic indicator in advanced pancreatic cancer.  Moreover, these researchers stated that similar studies in other cancer settings with larger sample sizes are needed to further validate the prognostic significance of the phase angle.

Sarode and associates (2015) stated that molecular alterations at the membrane, cytosol and nuclear level in cancer cells/tissues demonstrated variations in bioimpedance measure.  These researchers examined bioimpedance measurements between oral squamous cell carcinoma (OSCC) and normal tissue.  Study further involved clinicopathological correlation of bioimpedance values in OSCC.  The present study was comprised of 50 OSCC cases and 50 healthy control (HC) subjects.  A total of 4 electrical properties of OSCC were measured: Impedance (Z); Phase angle (9); Real part of impedance (R); and Imaginary part of impedance (X) at 6 frequencies: 20 Hz; 50 kHz; 1.3 MHz; 2.5 MHz; 3.7 MHz; and 5 MHz with the amplitude of the applied voltage limited to 200 mV.  The bioimpedance of OSCC as well as control group decreased as the measurement frequency increased from 20 Hz to 5 MHz.  The bioimpedance of OSCC was generally smaller than that of control group.  The mean bioimpedance of OSCC was found to be 4,493 ± 216.9 Ω and 370.0 ± 26.45 Ω and that of control group was 15,490 ± 287.2 Ω and 817.1 ± 7.227 Ω at frequencies of 20 Hz and 50 MHz, respectively which was statistically significant (p < 0.0001).  The values of phase angle, real and imaginary part of impedance of OSCC group were found to be significantly larger than that of control group (p < 0.0001) at 20 Hz and 50 MHz frequency.  Impedance values of OSCC decreased from stages I to IV.  Statistically significant differences in values of impedance were observed between stage I (4,881 ± 262.5 Ω) and IV (4,500 ± 181.6 Ω) (p = 0.0060) and also between stage I (4,881 ± 262.5 Ω) and III (4,376 ± 121.3 Ω) at frequency of 20 Hz (p-value 0.0005).  Statistically significant differences in values of impedance were also observed between well-differentiated (4,557 ± 260.8) and poorly-differentiated OSCC (4,347 ± 76.12) (p = 0.0004) but only at 20-Hz frequency.  The authors concluded that bioimpedance at a particular frequency showed significant alteration in OSCC tissue as compared to control; thus, it could be a potentially promising technique for detection of OSCC.

Hui et al (2017) examined the association of phase angle obtained from multi-frequency BIA (MF-BIA) with overall survival (OS) in patients with advanced cancer.  These investigators included consecutive patients with advanced cancer who had an outpatient palliative care consultation; MF-BIA was carried out to evaluate phase angle at 3 different frequencies (5-, 50-, and 250-kHz) on each hemi-body (right/left).  Survival analysis was carried out by means of the Kaplan-Meier method, log-rank test, and multi-variate Cox regression analysis.  Among 366 patients, the median OS was 250 days (95 % CI: 191 to 303 days).  The mean phase angle for 5-, 50-, and 250-kHz were 2.2°, 4.4°, and 4.2° on the right and 2.0°, 4.2° and 4.1° on the left, respectively.  For all 6 phase angles, a lower value was significantly associated with a poorer OS (p < 0.001).  After adjusting for cancer type, performance status, weight loss, and inflammatory markers, phase angle remained independently associated with OS (hazard ratio [HR] 0.85 per degree increase, 95 % CI: 0.72 to 0.99; p = 0.048).  The authors concluded that phase angle represented a novel objective prognostic factor in outpatient palliative cancer care setting, regardless of frequency and body sides.  Moreover, these researchers stated that future studies are needed to examine how phase angle values could be used to inform both patients with advanced cancer and clinicians in decision-making on the many complex issues in the last months of life, such as palliative procedures, chemotherapy and nutrition.

The authors stated that this study had several drawbacks.  First, the retrospective nature of data gathering meant that they were unable to include several key prognostic variables such as the Palliative Prognostic Score and C-reactive protein (CRP).  Second, patients needed to be able to stand on the scale for a few minutes to use the Inbody 720 device; and a few individuals seen at the outpatient clinic were excluded due to muscle weakness.  Therefore, the Inbody 720 device may not be feasible in the inpatient setting, although other MF-BIAs are available that could be used with patient in a supine position.

Pathiraja and colleagues (2020) noted that recent research has begun to emerge into the potential uses of electrical impedance technology in the detection and diagnosis of pre-malignant and malignant conditions.  In a systematic review, these investigators examined the clinical application of electrical impedance technology in the detection of malignant neoplasms.  They searched Embase Classic, Embase and Medline databases from 1980 to February 22, 2018 to identify studies reporting on the use of bioimpedance technology in the detection of pre-malignant and malignant conditions.  The ability to distinguish between tissue types was defined as the primary endpoint, and other points of interest were also reported.  A total of 731 articles were identified, of which 51 reported sufficient data for analysis.  These studies covered 16 different cancer subtypes in a total of 7,035 patients.  As the studies took various formats, a qualitative analysis of each cancer subtype's data was undertaken.  All the studies were able to show differences in electrical impedance and/or related metrics between malignant and normal tissue.  The authors concluded that electrical impedance technology provided a novel method for the detection of malignant tissue, with large studies of cervical, prostate, skin and breast cancers showing encouraging results.  Moreover, these researchers stated that while these studies provided promising insights into the potential of this technology as an adjunct in screening, diagnosis and intra-operative margin assessment, customized development as well as multi-center clinical trials are needed before it can be used reliably in the clinical detection of malignant tissue.

The authors stated that 1 major drawback of this review was that several of the studies (25/51) included in this systematic review used ex-vivo specimens; only the cervical, cutaneous and oral lesion studies exclusively looked at electrical impedance in pre-malignant and normal tissue.  One of the breast studies included a comparison between in-vivo and ex-vivo measurements of specimens and showed that various electrical impedance spectroscopy (EIS) metrics (conductivity and permittivity) clearly decreased as measurements were taken ex-vivo.  It is known that as soon as tissue is resected and loses its blood supply, the fluid status of the tissue changes, which in turn would affect the electrical conductivity and impedance properties of the tissue.  However, it is understandable that in these initial proof-of-concept studies where novel technology and techniques are being used for the first time, ex-vivo studies precede more realistic in-vivo studies.  Thus, further research examining the electrical impedance of these tissue types in-vivo would be needed before an assessment of the effectiveness of this technology could be made.  Another drawback was that many of the studies included had a small sample size, and had each reported on different outcomes, which therefore could not be statistically analyzed as a whole.  This heterogeneity was increased by the studies having multiple variables, such as frequency ranges applied by the studies’ tools, the specific impedance tool used as well as unreported ischemic times.  For the cancer types that have many studies reporting findings, the studies had often been conducted at the same institution using the same methodology but had not reported quantitative statistics that could be pooled for analysis.  Consequently, more meaningful statistical analysis of the results could not be reported at this early stage.  Nevertheless, qualitative analysis of the results was still possible, from which significant conclusions and further work can be planned.

Mansouri and co-workers (2020) noted that early detection of breast cancer saves lives; however, existing detecting techniques are invasive.  Electrical bioimpedance is a non-invasive approach and has a high diagnostic potential; and an impedance value different from the normal can predict a physiological abnormality.  These researchers employed a designed bioimpedance device for early detection of breast cancer.  A low-frequency current (1 kHz, 0.9 mA) was injected to each breast to measure the extracellular resistances.  The resistances of the 2 breasts were then measured, and if there was a significant difference, warning was displayed.  The performance was tested on a set of reference resistors, and the validation was carried out in-vitro on (NaCl) solutions and in-vivo on a group of 40 volunteer women.  The results confirmed that the electrical conductivity of an ionic solution was proportional to its concentration.  The concentration and the resistance were strongly correlated (correlation coefficient of 0.97).  The accuracy and the repeatability of the measures were satisfactory.  Early detection meant that clinicians could detect small extracellular concentration variations into the breast (from 0.6 g/L).  In-vivo measurements made it possible to set the threshold at 50 Ohm.  If the difference between the 2 measured breast resistances was greater than this threshold, the patient would be advised to consult a doctor promptly.  The authors concluded that the difference between measured resistances of the right and left breast was a pertinent parameter for early detection of cancer.  The lowest resistance value (RR or RL) could provide information on the breast affected by the cancer (right or left).  These investigators noted that various improvements in the system are possible; but the results are encouraging.  In the future, this system could be integrated into a bra.

These researchers stated that in order to improve their work, they will first perform a measurement campaign on patients with breast cancer as well as on healthy subjects.  This measurement campaign will improve their system and choose the best threshold.  Then, these investigators will increase the number of electrodes to accurately locate the tumor in the affected breast and to create an image that will be displayed on the smartphone.  This will allow having a smart mammograph by the electrical bioimpedance method.

Aleixo and colleagues (2020) stated that the loss of muscle mass, known as sarcopenia, is a natural process of aging that is associated with adverse health outcomes regardless of age.  Because cancer is a disease of aging, interest in sarcopenia and its potential impact in multiple cancer populations has increased significantly.  Bioelectrical impedance analysis is a guideline-accepted method for sarcopenia detection.  In a systematic review, these investigators examined the literature pertaining to BIA use in the detection of sarcopenia in adults with cancer.  They carried out a search of the literature for randomized controlled trials (RCTs) and observational studies using Medline, Cochrane CENTRAL, and Embase, through July 15, 2019.  For study inclusion, patients had to be aged 18 years or older and diagnosed with solid or hematological neoplasia, and BIA had to be used to detect sarcopenia.  A total of 5,045 articles were identified, of which 24 studies were selected for inclusion in the review (total number of 3,607 patients).  In 5 studies, BIA was rated comparable to axial computed tomography (CT) scan, calf circumference, or grip strength for sarcopenia screening.  In 14 studies, BIA-identified sarcopenia was associated with adverse clinical outcomes.  The authors concluded that the findings of this review suggested that BIA‐assessed sarcopenia could be of prognostic value for multiple types of cancer.  BIA is an affordable, portable, easy‐to‐use, effective method for detecting sarcopenia in adults with cancer before treatment and a viable alternative to CT, DXA scans, and MRIs in clinical practice.  These researchers stated that imaging studies have higher accuracy compared with BIA and remain the gold standard; however, their implementation complexity and cost reduce their applicability in oncologic clinical practice.  They stated that further research is needed to improve the understanding of how routine assessment of sarcopenia can lead to interventions that improve outcomes in patients with cancer.

The authors stated that the drawbacks of this study reflected the limitations of using BIA to identify sarcopenia.  Different scales, different BIA equipment, different equations and cut‐points for determining sarcopenia, and different types of cancers precluded meta‐analysis of our data.  Furthermore, a majority of patients included in this review were older, which may have influenced their hydration status and body mass index (BMI) at the time of BIA measurement.  This is a common concern for the use of BIA and is especially relevant in cancers that cause severe weight loss and hydration changes, such as gastro-intestinal (GI) and head and neck (H&N) cancers.  Interestingly, GI cancers were the most common type of cancer in this review, which confirmed that even in these patient populations, BIA can be effective when appropriate protocols are followed . It would also be informative to conduct BIA measures in a younger patient population to examine if outcomes remain similar to the older patients included in this review.  Another concern was that some studies had shown that BIA should be used with caution in morbidly obese patients (BMI greater than 35 kg/m2), as it may under-estimate body fat and over-estimate fat free mass.  These researchers also noted that not all societies accept BIA as a valuable method for lean mass estimation.  Recently, the Society of Sarcopenia Cachexia and Wasting Disorders (SCWD) recommended that physicians should make a formal diagnosis of sarcopenia using grip strength or chair stand and, if possible, a measurement of fat‐free mass.  SCWD recommends appendicular skeletal muscle per height squared estimated by dual‐energy x‐ray absorptiometry (DXA), but they also recognize that CT, BIA, ultrasound (US), or creatine dilution techniques may become as good or more accurate for estimating muscle mass in the future.  Furthermore, BIA was not strongly endorsed in the latest EWGSOP report for measuring muscle mass; however, it was recognized that BIA's portability, affordability, and availability made this measure a feasible tool for estimating muscle mass in many care settings.  These investigators also noted that Newcastle Ottawa Scale analysis rated 38 % of the studies as only fair quality, which indicated higher risk for bias.  Despite the wide spectrum of cancers included in this review, some types of cancer such as breast, melanoma, and pancreatic did not have BIA studies for sarcopenia.  Finally, there was a high degree of heterogeneity among the included studies.  BIA‐based estimates of sarcopenia can be influenced by the patient's ethnicity (note the differences in European and Asian guidelines pertaining to the use of BIA for sarcopenia detection), medical condition and co-morbidities, hydration, exercise history, and food intake.  These factors could influence the accuracy of BIA‐determined sarcopenia among patients, even within the same patient at different time points of the day.  It had been shown that multi-frequency BIA (using a combination of low and high frequencies to calculate intercellular water, extracellular water, and total body water) had a greater accuracy than single‐frequency BIA (which generally uses a 50‐kHz current that passes through extracellular and intracellular fluids for the estimation of total body water), especially in obese and under-weight patients.  These variables need to be considered in establishing optimal pretest preparation, selecting the equation to be used by the BIA software, and determining sarcopenia cutpoints for a specific patient population in order to reduce potential inaccuracies in BIA measurements.  It is suggested that in clinical practice, patients should receive instructions pertaining to hydration, food consumption, and exercise prior to the BIA, such as not drinking excessive amounts of water or performing vigorous physical activity 2 to 3 hours prior to the evaluation.  This is not unlike instructions provided to patients before tests such as a routine blood pressure measurement.  These investigators stated that the value of BIA would also be greatly enhanced by an international consensus on cut-points for BIA‐assessed sarcopenia in different cancer populations.  Furthermore, additional research is needed to examine if BIA is useful or accurate for detecting low lean muscle mass for the diagnosis of sarcopenia in patients with cancers that were under‐represented in this review, such as breast cancer and melanoma, and in younger patients.  In addition, further research is needed to examine the potential benefits of BIA‐generated data for treatment decisions and overall cancer care.

Lee et al (2021) stated that BIA provides information on body composition and nutritional status; however, it is unclear if the pre-operative edema index or phase angle predicts post-operative complication or mortality in patients with hepato-cellular carcinoma (HCC).  These investigators examined if pre-operative BIA could predict post-operative complications and survival in patients with HCC.  A total of 79 patients who underwent hepatectomy for HCC were prospectively enrolled and BIA was carried out before surgery.  Post-operative ascites or acute kidney injury (AKI) and patients' survival were monitored following surgery.  Among 79 patients, 35 (44.3 %) developed ascites or AKI following hepatectomy.  In multi-variate analysis, a high pre-operative edema index (extracellular water/total body water) (greater than 0.384) (odds ratio [OR] 3.96; 95 % CI: 1.03 to 15.17; p = 0.045) and higher fluid infusion during surgery (OR 1.36; 95 % CI: 1.04 to 1.79; p = 0.026) were identified as significant risk factors for ascites or AKI following hepatectomy.  Subgroup analyses showed that the edema index was a significant predictor of ascites or AKI in patients with cirrhosis.  Tumor size was the only significant predictive factor for short-term survival after hepatectomy.  The authors concluded that the pre-operative edema index using BIA could be used as a predictor of post-hepatectomy complication, especially in patients with liver cirrhosis.

The authors stated that this study had several drawbacks.  Although the study was carried out on patients with early-stage operable HCC, they did not control for HCC stage in the study.  Similarly, although the study included only patients with preserved liver function who underwent surgery, the study population had various etiologies.  These factors could also have affected post-operative morbidity.  Furthermore, this study could not consider all other factors that could affect the edema index.

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
CPT codes not covered if selection criteria are met:
0358T	Bioelectrical impedance analysis whole body composition assessment, with interpretation and report
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):
C00.0 - C96.9	Malignant Neoplasms
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]
Z51.5	Encounter for palliative care [palliative cancer care]

The above policy is based on the following references: