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DESCRIPTIONIn 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 outpt. 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 BioZTM 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.
InnocorTM (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 InnocorTM 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.
POLICYIn the ambulatory care and outpatient setting, thoracic bioimpedance and inert gas rebreathing is considered investigational.
Investigative service is defined as the use of any treatment procedure, facility, equipment, drug, device, or supply not yet recognized by certifying boards and/or approving or licensing agencies or published peer review criteria as standard, effective medical practice for the treatment of the condition being treated and as such therefore is not considered medically necessary.
The coverage guidelines outlined in the Medical Policy Manual should not be used in lieu of the Member's specific benefit plan language.
POLICY HISTORY7/15/2004: 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.
Blue Cross Blue Shield Association policy # 2.02.12
Hayes Medical Technology Directory
CODE REFERENCEAll codes billed are considered investigational and not eligible for coverage.