Also, the committee found that not all physicians use the same ABI thresholds to diagnose peripheral disease. The Writing Committee disclosed that it is not commonly understood that ABI requires one to measure two separate systolic arterial (dorsalis pedis and posterior tibial) pressures at each ankle and the systolic brachial arterial pressures in both arms in order to compare the pressures in what becomes a comparative ratio. Specifically, the committee reviewed two methods used to report ABI and the literature showing that these methods had more significant clinical implications than are generally realized.
The Doppler method to calculate the ABI requires the use of continuous-wave Doppler probe for the detection of arterial flow. The clinician puts the probe into position over the artery of interest (brachial, dorsalis pedis (DP), posterior tibial (PT)). One then applies a pneumatic pressure cuff to the upper arm for the brachial assessment or to the ankle for the dorsalis pedis and posterior tibial assessment. Inflate the cuff to 20 mmHg above the pressure wherein blood flow stops and then deflate it slowly until there is reappearance of the Doppler flow signal (visual and/or audio). The corresponding cuff pressure is the systolic blood pressure. One records each of the three pressures bilaterally and uses them to calculate the ABI. The calculation for ABI requires the clinician to divide the higher of the posterior tibial or dorsalis pedis pressure by the higher of the arm systolic blood pressure, and report this ratio separately for each leg in patients with symptoms of PAD.
The Writing Committee also addressed other methods of performing ABI tests and these methods included the use of plethysmography, photoplethysmography, auscultation, and pulse palpation. The committee concluded that none were acceptable alternatives to Doppler ABI in terms of reproducibility, specificity and/or sensitivity, and that clinicians should not use them for clinical decision-making.
What You Should Know About The Medicare Requirements
As of January 1, 2011, Medicare issued the CPT code language for non-invasive physiologic peripheral artery tests (CPT code 93922/93923). The code underwent a significant change from previous language. These changes were intended to reflect the considerable clinical evidence relative to best practice when using ABI as part of the diagnostic array that is required to detect and manage PAD. To that end, the 2011 language identifies the specific methods, levels and arterial assessment locations required to generate a reimbursable ABI as part of an overall lower extremity arterial assessment. With the 2012 AHA Scientific Statement, these changes are fully explained and validated in terms of published evidence.19
The CPT 2011 code makes it clear that the Doppler method is required to perform an ABI test that meets the Medicare requirement for reimbursement eligibility using CPT Codes 93922-93924. In addition to the CPT 2011 language change, several regional Medicare carriers revised the language in their local coverage determinations to specifically identify non-covered methods such as oscillometry or photoplethysmography.
Clinicians would use CPT code 93922 when performing a “limited” arterial study involving bilateral assessments on one to two levels on the lower extremity. One would employ CPT code 93923 when performing “complete” arterial study involving bilateral assessments on three or more levels on the lower extremity. The CPT code 93923 is also appropriate for a single level study with provocative functional maneuvers (i.e. reactive hyperemia).
For more information on the Medicare requirements for non-invasive physiologic arterial testing, you should contact your regional Medicare provider.
Podiatrists play a key role in the detection, treatment and management of patients with PAD. Incorporating patient awareness initiatives, performing diagnostic assessments and utilizing the optimal testing methods will provide optimal outcomes.
Dr. Rogers is the Medical Director of the Amputation Prevention Center at the Sherman Oaks Hospital in Sherman Oaks, Ca. He is an Assistant Professor of Podiatry at the Western University of Health Sciences in Pomona, Ca.