What You Should Know About Using NIV Studies

By Dana Giacalone, DPM, and Khurram Khan, DPM
You can also use TCOM to determine the level of amputation and adjunctively to help diagnose PVD.6 Accuracy in testing depends on the local factors (skin thickness, capillary formation and density, presence of inflammation or edema) and systemic factors (lung function, FI02, blood Hg level, cardiac output).4,6 Keep in mind you can’t use TCOMs on the plantar aspect of the foot, on curved surfaces like toes or malleoli or when the patient has cellulitis.4 You would obtain readings by placing electrodes in designated areas. The central reference position is 5 cm below the middle left clavicle. The peripheral positions are 10cm AK, 5 cm BK, medial foot and the lateral foot. You would apply a buffer solution to electrodes and the attached probes begin heating underlying skin. After equilibration, you should obtain readings at three- to five-minute intervals and you can add to your baseline testing by including an oxygen challenge with inhalation of 100 percent oxygen. In order to detect positive increases in value, you would need to compare baseline readings to oxygen challenge. A positive response is an increase of at least twice the baseline reading. Successful wound healing has been shown to occur with >40mmHg. Failure to heal is indicated by <20mmHg with necrosis at 10mmH or less.6,7,8 Grolman, et. al., found that patients with a TCOM increase of 10 mmHg or greater had a 70 percent chance to heal ischemic wounds with adjunct therapy.9 They also report that TCOM was an excellent predictor of the severity of tissue hypoxia associated with peripheral arterial occlusive disease. Final Notes NIV is a valuable tool in screening for peripheral arterial disease. The cost of NIV studies is substantially less in comparison to arteriography. Sykes states that overall NIV testing is less than $500 versus angiograms which cost over $2,000.1 It is important to emphasize the role of recognizing peripheral arterial disease and instituting appropriate treatment regimens. A recent study, the Peripheral Arterial Disease (PAD) Detection, Awareness and Treatment in Primary Care, confirmed the relative lack of awareness of PAD by patients and their physicians. Eighty-three percent of patients with prior PAD were aware of their condition, although only 49 percent of physicians were aware of their patients’ diagnosis. Classic claudication was uncommon in 5 to 15 percent of patients.8 The study also confirmed the lack of treatment for patients with PAD in comparison with those having other cardiovascular diseases.8Dr. Giacalone is a first-year resident and Dr. Khan is a second-year resident at the University of Texas Health Science Center. Dr. Steinberg is an Assistant Professor in the Department of Orthopaedics/Podiatry Service at the University of Texas Health Science Center.


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