Thoracic Electrical Bioimpedance in the Outpatient Setting

POLICY NUMBER

L.2.02.402

DESCRIPTION

In the intensive care unit, hemodynamic monitoring using a pulmonary artery catheter (also referred to as right heart catheterization) is commonly used to provide prognostic information and guide treatment decisions. Cardiac output is commonly measured as part of such monitoring in patients with heart failure, shock syndromes, and after coronary artery bypass graft surgery. Techniques include thermodilution, dye dilution, or the Fick method, although thermodilution is most commonly used. Thoracic electrical bioimpedance and inert gas rebreathing are two (2) techniques that have been investigated for many years as a non-invasive alternative for measuring cardiac output. Bioimpedance is defined as the electrical resistance of tissue to the flow of current. For example, when small electrical signals are transmitted through the thorax, the current travels along blood-filled aorta, which is the most conductive area. Changes in bioimpedance, resulting from the pulsatile changes in volume and velocity of blood in the aorta, are inversely proportional to the stroke volume (cardiac output equals the stroke volume times heart rate). Inert gas rebreathing is based on the observation that the absorption and disappearance of a blood soluble gas is proportional to cardiac blood flow. The patient is asked to breathe and rebreathe form a rubber bag filled with oxygen mixed with foreign gases; typically nitrous oxide and sulphur hexafluoride. The nitrous oxide is soluble in blood and is therefore absorbed during the blood's passage through the lungs at a rate that is proportional to the blood flow. The sulfur hexafluoride is insoluble in blood and therefore stays in the gas phase and is used to determine the lung volume from which the soluble gas is removed. These gases and CO-2 are measured continuously and simultaneously at the mouthpiece.

Development of a noninvasive measurement would permit more convenient and safer monitoring in the intensive care unit, and could be used for monitoring in other settings, such as the emergency room, on the general medical floor, or outpatient clinic. In the outpatient clinic thoracic bioimpedance has been investigated as a technique to optimize drug therapy in patients with congestive heart failure. Echocardiography, transesophageal echocardiography (TEE), and Doppler ultrasound are other noninvasive methods for monitoring cardiac output.

The BioZ^TM is one of a number of electrical bioimpedance devices approved through the 510(k) process for marketing by the U.S. Food and Drug Administration (FDA) that measures thoracic bioimpedance.

Innocor^TM (Innovision, Denmark), an inert gas rebreathing device, received FDA approval through the 510(k) approval process in March 2006 as substantially equivalent to two predicate technologies, thermodilution and the direct Fick method. The Innocor^TM device is approved for the determination of a number of hemodynamic parameters, principally cardiac output.

Note: This policy only addresses use of this technique in ambulatory care and outpatient settings.

POLICY

In the ambulatory care and outpatient setting, thoracic bioimpedance and inert gas rebreathing is considered investigational.

POLICY EXCEPTIONS

None

POLICY GUIDELINES

The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.

Investigative is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized as a generally accepted standard of good medical practice for the treatment of the condition being treated and; therefore, is not considered medically necessary. For the definition of Investigative, “generally accepted standards of medical practice” means standards that are based on credible scientific evidence published in peer-reviewed medical literature generally recognized by the relevant medical community, and physician specialty society recommendations, and the views of medical practitioners practicing in relevant clinical areas and any other relevant factors. In order for equipment, devices, drugs or supplies [i.e, technologies], to be considered not investigative, the technology must have final approval from the appropriate governmental bodies, and scientific evidence must permit conclusions concerning the effect of the technology on health outcomes, and the technology must improve the net health outcome, and the technology must be as beneficial as any established alternative and the improvement must be attainable outside the testing/investigational setting.

POLICY HISTORY

7/15/2004: Approved by Medical Policy Advisory Committee (MPAC)

10/1/2004: Code Reference section completed

9/13/2006: Policy updated. Updates approved by Medical Policy Advisory Committee (MPAC) 7/27/2006

9/13/2006: Code reference section updated. CPT codes 0104T and 0105T codes added

5/15/2009: Policy reviewed, no changes

3/22/2010: Code reference section updated. Description revised for CPT code 93701.

07/23/2015: Code Reference section updated for ICD-10.

06/08/2016: Policy number L.2.02.402 added. Investigative definition updated in Policy Guidelines.

02/06/2023: Policy reviewed; no changes.

03/15/2024: Policy reviewed; no changes.

03/27/2025: Policy reviewed; no changes.

SOURCE(S)

1. Blue Cross Blue Shield Association policy # 2.02.12

2. Hayes Medical Technology Directory

CODE REFERENCE

This may not be a comprehensive list of procedure codes applicable to this policy. 

Investigational Codes

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