CMS Pub. 100-03, ch. 1, § 20.14

CIM 50-6

Plethysmography involves the measurement and recording (by one of several methods) of

changes in the size of a body part as modified by the circulation of blood in that part.

Plethysmography is of value as a noninvasive technique for diagnostic, preoperative and

postoperative evaluation of peripheral artery disease in the internal medicine or vascular

surgery practice. It is also a useful tool for the preoperative podiatric evaluation of the

diabetic patient or one who has intermittent claudication or other signs or symptoms

indicative of peripheral vascular disease which have a bearing on the patient’s candidacy

for foot surgery.

The oldest form of plethysmography is the venous occlusive pneumoplethysmography.

This method is cumbersome, time consuming, and requires considerable training to give

useful, reproducible results. Nonetheless, in the setting of the hospital vascular

laboratory, this technique is considered a reasonable and necessary procedure for the

diagnostic evaluation of suspected peripheral arterial disease. It is unsuitable for routine

use in the physician’s office.

Recently, however, a number of other plethysmographic methods have been developed

which make use of phenomena such as changes in electric impedance or changes in

segmental blood pressure at constant volume to assess regional perfusion. Several of

these methods have reached a level of development which makes them clinically

valuable.

Medicare coverage is extended to those procedures listed in Category I below when used

for the accepted medical indications mentioned above. The procedures in Category II are

still considered experimental and are not covered at this time. Denial of claims because a

noncovered procedure was used or because there was no medical indication for

plethysmographic evaluation of any type should be based on §1862(a)(1) of the Act.

Category I - Covered

Segmental Plethysmography - Included under this procedure are services performed with

a regional plethysmograph, differential plethysmograph, recording oscillometer, and a

pulse volume recorder.

Electrical Impedance Plethysmography

Ultrasonic Measurement of Blood Flow (Doppler) - While not strictly a

plethysmographic method, this is also a useful tool in the evaluation of suspected

peripheral vascular disease or preoperative screening of podiatric patients with suspected

peripheral vascular compromise. (See §220.5 for the applicable coverage policy on this

procedure.)

Oculoplethysmography - See §20.17, “Noninvasive Tests of Carotid Function.”

Strain Gauge Plethysmography - This test is based on recording the non-pulsatile aspects

of inflowing blood at various points on an extremity by a mercury-in-silastic strain gauge

sensor. The instrument consists of a chart recorder, an automatic cuff inflation and

deflation system, and a recording manometer.

Category II - Experimental

The following methods have not yet reached a level of development such as to allow their

routine use in the evaluation of suspected peripheral vascular disease.

Inductance Plethysmography - This method is considered experimental and does not

provide reproducible results.

Capacitance Plethysmography - This method is considered experimental and does not

provide reproducible results.

Mechanical Oscillometry - This is a nonstandardized method which offers poor

sensitivity and is not considered superior to the simple measurement of peripheral blood

pressure.

Photoelectric Plethysmography - This method is considered useful only in determining

whether or not a pulse is present and does not provide reproducible measurements of

blood flow.

Differential plethysmography, on the other hand, is a system which uses an impedance

technique to compare pulse pressures at various points along a limb, with a reference

pressure at the mid-brachial or wrist level. It is not clear whether this technique, as

usually performed in the physician’s office, meets the definition of plethysmography

because quantitative measurements of blood flow are usually not made. It has been

concluded, in any event, that the differential plethysmography system is a blood pulse

recorder of undetermined value which has the potential for significant overutilization.

Therefore, reimbursement for studies done by techniques other than venous occlusive

pneumoplethysmography should be denied, at least until additional data on these devices,

including controlled clinical studies, become available.