Thoracic Electrical Bioimpedance for Cardiac Output Monitoring

Number: 0472


  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.


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.

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]

The above policy is based on the following references:

  1. U.S. Department of Health and Human Services, Center for Medicare & Medicaid Services (CMS). Decision memo for electrical bioimpedance for cardiac output monitoring (CAG-00001R). Medicare Coverage Database. Baltimore, MD: CMS; August 7, 2003.
  2. Jordan HS, Ioannidis JPA, Goudas LC, et al. and the Tufts-New England Medical Center AHRQ Evidence-based Practice Center (EPC). Thoracic electrical bioimpedance. Evidence Report/Technology Assessment. EPC Technical Support of the CPTA Technology Assessment Program. Contract No. 290-97-0019, Task Order #10. Rockville, MD: Agency for Healthcare Research and Quality (AHRQ); revised November 27, 2002.
  3. Littman L, Lasater M. Cost effectiveness of noninvasive hemodynamic monitoring as a screening tool prior to initiation of inotrope infusion. J Cardiovasc Manag. 1999;10(2):29-30.
  4. Zacek P, Kunes P, Kobzova E, et al. Thoracic electrical bioimpedance versus thermodilution in patients post open-heart surgery. Acta Medica (Hradec Kralove). 1999;42(1):19-23.
  5. Velmahos GC, Wo CC, Demetriades D, et al. Invasive and noninvasive hemodynamic monitoring of patients with cerebrovascular accidents. West J Med. 1998;169(1):17-22.
  6. Becker K Jr. Resolved: A pulmonary artery catheter should be used in the management of the critically ill patient. Con. J Cardiothorac Vasc Anesth. 1998;12(2 Suppl 1):13-16.
  7. Weiss SJ, Kulik JP, Calloway E. Bioimpedance cardiac output measurements in patients with presumed congestive heart failure. Acad Emerg Med. 1997;4(6):568-573.
  8. Thangathurai D, Charbonnet C, Roessler P, et al. Continuous intraoperative noninvasive cardiac output monitoring using a new thoracic bioimpedance device. J Cardiothorac Vasc Anesth. 1997;11(4):440-444.
  9. Wong KL, Hou PC. The accuracy of bioimpedance cardiography in the measurement of cardiac output in comparison with thermodilution method. Acta Anaesthesiol Sin. 1996;34(2):55-59.
  10. World MJ. Methods of estimating cardiac output in the field. QJM. 1996;89(6):457-462.
  11. Barney J. Thoracic electrical bioimpedance device. Crit Care Med. 1996;24(6):1090-1091.
  12. Weiss S, Calloway E, Cairo J, et al. Comparison of cardiac output measurements by thermodilution and thoracic electrical bioimpedance in critically ill versus non-critically ill patients. Am J Emerg Med. 1995;13(6):626-631.
  13. Doering L, Lum E, Dracup K, et al. Predictors of between-method differences in cardiac output measurement using thoracic electrical bioimpedance and thermodilution. Crit Care Med. 1995;23(10):1667-1673.
  14. Shoemaker WC, Wo CC, Bishop MH, et al. Multicenter trial of a new thoracic electrical bioimpedance device for cardiac output estimation. Crit Care Med. 1994;22(12):1907-1912.
  15. Smith MA. Noninvasive hemodynamic monitoring with thoracic electrical bioimpedance. Crit Care Nurse. 1994;14(5):56-59.
  16. Castor G, Klocke RK, Stoll M, et al. Simultaneous measurement of cardiac output by thermodilution, thoracic electrical bioimpedance and Doppler ultrasound. Br J Anaesth. 1994;72(1):133-138.
  17. Ferraro S, D'Alto M, Maddalena G, et al. The usefulness of bioimpedance in patient monitoring in an intensive-therapy heart-surgery unit: A comparison with thermodilution. Cardiologia. 1993;38(9):577-583.
  18. Sageman WS, Amundson DE. Thoracic electrical bioimpedance measurement of cardiac output in postaortocoronary bypass patients. Crit Care Med. 1993;21(8):1139-1142.
  19. Young JD, McQuillan P. Comparison of thoracic electrical bioimpedance and thermodilution for the measurement of cardiac index in patients with severe sepsis. Br J Anaesth. 1993;70(1):58-62.
  20. Atkins CS. AANA Journal course: New technologies in anesthesia: Update for nurse anesthetists--noninvasive, continuous, cardiac output monitoring by thoracic electrical bioimpedance. 16. AANA J. 1991;59(5):445-452.
  21. Clancy TV, Norman K, Reynolds R, et al. Cardiac output measurement in critical care patients: Thoracic Electrical Bioimpedance versus thermodilution. J Trauma. 1991;31(8):1116-1121.
  22. Handelsman H. Measuring cardiac output by electrical bioimpedance. Agency for Health Care Policy and Research (AHCPR) Health Technology Assessment Report No. 6. AHCPR Pub. No. 92-0073. Bethesda, MD: AHCPR; September 1992.
  23. Sageman WS, Riffenburgh RH, Spiess BD. Equivalence of bioimpedance and thermodilution in measuring cardiac index after cardiac surgery. J Cardiothorac Vasc Anesth. 2002;16(1):8-14.
  24. Weiss SJ, Ernst AA, Godorov G, et al. Bioimpedance-derived differences in cardiac physiology during exercise stress testing in low-risk chest pain patients. South Med J. 2003;96(11):1121-1127.
  25. Moshkovitz Y, Kaluski E, Milo O, et al. Recent developments in cardiac output determination by bioimpedance: Comparison with invasive cardiac output and potential cardiovascular applications. Curr Opin Cardiol. 2004;19(3):229-237. 
  26. Wang DJ, Gottlieb SS. Impedance cardiography: More questions than answers. Curr Heart Fail Rep. 2006;3(3):107-113.
  27. U.S. Department of Health and Human Services, Center for Medicare & Medicaid Services (CMS). Decision Memo for Electrical Bioimpedance for Cardiac Output Monitoring (CAG-00001R2). Medicare Coverage Database. Baltimore, MD: CMS; November 20, 2006.
  28. Raval NY, Squara P, Cleman M, et al. Multicenter evaluation of noninvasive cardiac output measurement by bioreactance technique. J Clin Monit Comput. 2008;22(2):113-119.
  29. Gujjar AR, Muralidhar K, Banakal S, et al. Non-invasive cardiac output by transthoracic electrical bioimpedence in post-cardiac surgery patients: Comparison with thermodilution method. J Clin Monit Comput. 2008;22(3):175-180.
  30. Gujjar AR, Muralidhar K, Bhandopadhyaya A, et al. Transthoracic electrical bioimpedence cardiac output: Comparison with multigated equillibrium radionuclide cardiography. J Clin Monit Comput. 2010;24(2):155-159.
  31. Taylor K, La Rotta G, McCrindle BW, et al. A comparison of cardiac output by thoracic impedance and direct fick in children with congenital heart disease undergoing diagnostic cardiac catheterization. J Cardiothorac Vasc Anesth. 2011;25(5):776-779.
  32. Faini A, Omboni S, Tifrea M, et al. Cardiac index assessment: Validation of a new non-invasive very low current thoracic bioimpedance device by thermodilution. Blood Press. 2014;23(2):102-108.
  33. Cote CJ, Sui J, Anderson TA, et al. Continuous noninvasive cardiac output in children: Is this the next generation of operating room monitors? Initial experience in 402 pediatric patients. Paediatr Anaesth. 2015;25(2):150-159.
  34. Sangkum L, Liu GL, Yu L, et al. Minimally invasive or noninvasive cardiac output measurement: An update. J Anesth. 2016;30(3):461-480.
  35. Elwan MH, Hue J, Green SJ, et al. Thoracic electrical bioimpedance versus suprasternal Doppler in emergency care. Emerg Med Australas. 2017;29(4):391-393.
  36. Nguyen LS, Squara P. Non-invasive monitoring of cardiac output in critical care medicine. Front Med (Lausanne). 2017;4:200.
  37. Joosten A, Desebbe O, Suehiro K, et al. Accuracy and precision of non-invasive cardiac output monitoring devices in perioperative medicine: A systematic review and meta-analysis. Br J Anaesth. 2017;118(3):298-310.
  38. Magliocca A, Rezoagli E, Anderson TA, et al. Cardiac output measurements based on the pulse wave transit time and thoracic impedance exhibit limited agreement with thermodilution method during orthotopic liver transplantation. Anesth Analg. 2018;126(1):85-92.