The signal is proportional to the quantity of red blood cells in the cutaneous circulation. Deflate the cuff and take note when the whooshing sound returns. The brachial blood pressure is divided into the highest of the PTA and DPA pressures. The pitch of the duplex signal changes in proportion to the velocity of the blood with high-pitched harsh sounds indicative of stenosis. The absolute value of the oxygen tension at the foot or leg, or a ratio of the foot value to chest wall value can be used. A high ankle brachial index is associated with greater left ventricular mass MESA (Multi-Ethnic Study of Atherosclerosis). Eur J Radiol 2004; 50:303. the right brachial pressure is 118 mmHg. Index values are calculated at each level. Prevalence and significance of unrecognized lower extremity peripheral arterial disease in general medicine practice*. These tests generally correlate to clinical symptoms and are used to stratify the need for further evaluation and treatment. The ABI in patients with severe disease may not return to baseline within the allotted time period. Value of toe pulse waves in addition to systolic pressures in the assessment of the severity of peripheral arterial disease and critical limb ischemia. 0.90); and borderline values defined as 0.91 to 0.99. Diabetes Care 1989; 12:373. http://www.iwgdf.org/index.php?option=com_content&task=view&id=43&Itemid=63. Local edema, skin temperature, emotional state (sympathetic vasoconstriction), inflammation, and pharmacologic agents limit the accuracy of the test. Romano M, Mainenti PP, Imbriaco M, et al. Normal pressures and waveforms. Normal is about 1.1 and less . Use of ankle brachial pressure index to predict cardiovascular events and death: a cohort study. The upper extremity arterial examination normally starts at the proximal subclavian artery ( Fig. 320 0 obj <>/Filter/FlateDecode/ID[<3FFBC48D78E83144874902B92858EA97><9129FADFCA4B5942901C654B211D0387>]/Index[299 34]/Info 298 0 R/Length 104/Prev 166855/Root 300 0 R/Size 333/Type/XRef/W[1 3 1]>>stream (See 'Pulse volume recordings'below.). ), The normal ABI is 0.9 to as high as 1.3. ACC/AHA 2005 Practice Guidelines for the management of patients with peripheral arterial disease (lower extremity, renal, mesenteric, and abdominal aortic): a collaborative report from the American Association for Vascular Surgery/Society for Vascular Surgery, Society for Cardiovascular Angiography and Interventions, Society for Vascular Medicine and Biology, Society of Interventional Radiology, and the ACC/AHA Task Force on Practice Guidelines (Writing Committee to Develop Guidelines for the Management of Patients With Peripheral Arterial Disease): endorsed by the American Association of Cardiovascular and Pulmonary Rehabilitation; National Heart, Lung, and Blood Institute; Society for Vascular Nursing; TransAtlantic Inter-Society Consensus; and Vascular Disease Foundation. 2, 3 Later, it was shown that the ABI is an . Vascular testing may be indicated for patients with suspected arterial disease based upon symptoms (eg, intermittent claudication), physical examination findings (eg, signs of tissue ischemia), or in patients who are asymptomatic with risk factors for atherosclerosis (eg, smoking, diabetes mellitus) or other arterial pathology (eg, trauma, peripheral embolism) [, ]. (A) Following the identification of the subclavian artery on transverse plane (see. Clinical trials for claudication. The radial artery takes a course around the thumb to send branches to the thumb (princeps pollicis) and a lateral digital branch to the index finger (radialis indices). Wound healing in forefoot amputations: the predictive value of toe pressure. The result may be occlusion or partial occlusion. 13.18 ) or on Doppler spectral waveforms at the level of occlusion, and a damped, monophasic Doppler signal distal to the obstruction (see Fig. Arch Intern Med 2005; 165:1481. Brain Anatomy. Kuller LH, Shemanski L, Psaty BM, et al. The TBI is obtained by placing a pneumatic cuff on one of the toes. A potential, severe complication associated with use of gadolinium in patients with renal failure is nephrogenic systemic sclerosis/nephrogenic fibrosing dermopathy, and therefore gadolinium is contraindicated in these patients. Diabetes Care 2008; 31 Suppl 1:S12. Hiatt WR. Because the arm arteries are mostly superficial, high-frequency transducers are used. Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II). Proximal to a high-grade stenosis with minimal compensatory collateralization, a thumping sound is heard. Is there a temperature difference between hands or finger(s)? If the fingers are symptomatic, PPGs (see Fig. The normal value for the WBI is 1.0. The ABI is generally, but not absolutely, correlated with clinical measures of lower extremity function such as walking distance, speed of walking, balance, and overall physical activity [13-18]. Furthermore, the vascular anatomy of the hand described herein is a simplified version of the actual anatomy because detailing all of the arterial variants of the hand is beyond the scope of this chapter. Specialized imaging of the hand can be performed to detect disease of the digital arteries. The result is the ABI. . Note the dramatic change in the Doppler waveform. Decreased peripheral vascular resistance is responsible for the loss of the reversed flow component and this finding may be normal in older patients or reflect compensatory vasodilation in response to an obstructive vascular lesion. A normal high-thigh pressure excludes occlusive disease proximal to the bifurcation of the common femoral artery. Note that although the pattern is one of moderate resistance, blood flow is present through diastole. Note that the waveform is entirely above the baseline. ABI is measured by dividing the ankle systolic pressure by brachial systolic pressure. The analogous index in the upper extremity is the wrist-brachial index (WBI). BMJ 1996; 313:1440. (See "Exercise physiology".). Norgren L, Hiatt WR, Dormandy JA, et al. The search terms "peripheral nerve", "quantitative ultrasound", and "elastography ultrasound&rdquo . Arterial occlusion distal to the ankle or wrist can be detected using digit plethysmography, which is performed by placing small pneumatic cuffs on each of the digits of the hands or feet depending upon the disease being investigated. Bund M, Muoz L, Prez C, et al. 13.13 ). Curr Probl Cardiol 1990; 15:1. Validated criteria for the visceral vessels are given in the table (table 3). Systolic blood pressure - the top number in a blood pressure reading that reflects pressure within the arteries when the heart beats - averaged 5.5 mmHg higher at the wrist than at the upper arm . or provide information that will alter the course of treatment should be performed. The subclavian artery gives rise to the axillary artery at the lateral aspect of the first rib. Ankle-brachial index is calculated as the systolic blood pressure obtained at the ankle divided by the systolic blood pressure obtained at the brachial . McDermott MM, Kerwin DR, Liu K, et al. These articles are written at the 10thto 12thgrade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon. PAD also increases the risk of heart attack and stroke. A common fixed protocol involves walking on the treadmill at 2 mph at a 12 percent incline for five minutes or until the patient is forced to stop due to pain (not due to SOB or angina). Mohler ER 3rd. According to the ABI calculator, a normal test result falls in the 0.90 to 1.30 range, meaning the blood pressure in your legs should be equal to or greater . It goes as follows: Right ABI = highest right ankle systolic pressure / highest brachial systolic pressure. Velocities in normal radial and ulnar arteries range between 40 and 90cm/s, whereas velocities within the palmar arches and digits are lower. Zierler RE. The upper extremity arterial system takes origin from the aortic arch ( Fig. Ankle and Toe Brachial Index Interpretation ABI (Ankle brachial index)= Ankle pressure/ Brachial pressure. TRANSCUTANEOUS OXYGEN MEASUREMENTSTranscutaneous oxygen measurement (TcPO2) may provide supplemental information regarding local tissue perfusion and the values have been used to assess the healing potential of lower extremity ulcers or amputation sites. McDermott MM, Greenland P, Liu K, et al. (See 'Exercise testing'above. Imaging of hand arteries requires very high frequency transducers because these vessels are extremely small and superficial. DBI < 0.75 are typically considered abnormal. 13.1 ). (See 'Transcutaneous oxygen measurements'above. These objectives are met by obtaining one or more tests including segmental limb pressures, calculation of index values (ankle-brachial index, wrist-brachial index, toe-brachial index), pulse volume recordings, exercise testing, digit plethysmography and transcutaneous oxygen measurements. Quantitative segmental pulse volume recorder: a clinical tool. Face Age. Surgery 1995; 118:496. ABI = ankle/ brachial index. A normal toe-brachial index is 0.7 to 0.8. Compared to the arm, lower blood pressure in the leg suggests blocked arteries due to peripheral artery disease(PAD). O'Hare AM, Katz R, Shlipak MG, et al. Systolic finger pressure of < 70 mm Hg and brachial-finger pressure gradients of > 35 mmHg are suggestive of proximal arterial obstruction, i.e. However, because arteriography exposes the patient to radiation and other complications associated with percutaneous arterial access and iodinated contrast, other modalities including computed tomography and magnetic resonance imaging have become important alternative methods for vascular assessment. N Engl J Med 1964; 270:693. Thus, WBIs are typically measured only when the patient has clinical signs or symptoms consistent with upper extremity arterial stenosis or occlusion. McDermott MM, Ferrucci L, Guralnik JM, et al. Cuffs are placed and inflated, one at a time, to a constant standard pressure. It is a screen for vascular disease. Resting ABI is the most commonly used measurement for detection of PAD in clinical settings, although variation in measurement protocols may lead to differences in the ABI values obtained. Values greater than 1.40 indicate noncompressible vessels and are unreliable. The four-cuff technique introduces artifact because the high-thigh cuff is often not appropriately 120 percent the diameter of the thigh at the cuff site. ), Contrast arteriography remains the gold standard for vascular imaging and, under some circumstances (eg, acute ischemia), is the primary imaging modality because it offers the benefit of potential simultaneous intervention. Pulse volume recordings which are independent of arterial compression are preferentially used instead. Wolf EA Jr, Sumner DS, Strandness DE Jr. An index under 0.90 means that blood is having a hard time getting to the legs and feet: 0.41 to 0.90 indicates mild to moderate peripheral artery disease; 0.40 and lower indicates severe disease. Resnick HE, Foster GL. The Ankle Brachial Index (ABI Test) is an important way to diagnose peripheral vascular disease. Carter SA, Tate RB. endstream endobj startxref 2012 Dec 11;126 (24):2890-909. doi: 10.1161/CIR.0b013e318276fbcb. Thrombus or vasculitis can be visualized directly with gray-scale imaging, but color and power Doppler imaging are used to determine vessel patency and to assess the degree of vessel recanalization following thrombolysis. (See 'Other imaging'above. The degree of these changes reflects disease severity [34,35]. Subclinical disease as an independent risk factor for cardiovascular disease. 1533 participants with PAD diagnosed by a vascular specialist were prospectively recruited from four out-patient clinics in Australia. Once you know you have PAD, you can repeat the test to see how you're doing after treatment. Ultrasound is the mainstay for vascular imaging with each mode (eg, B-mode, duplex) providing specific information that is useful depending upon the vascular disorder. Pulse volume recordings are most useful in detecting disease in calcified vessels which tend to yield falsely elevated pressure measurements. (See 'Continuous wave Doppler'below and 'Duplex imaging'below.). (See 'Ankle-brachial index'above and 'Physiologic testing'above and 'Ultrasound'above and 'Other imaging'above. Upper extremity disease is far less common than. The brachial artery continues down the arm to trifurcate just below the elbow into the radial, ulnar, and interosseous (or median) arteries. Compared to the arm, lower blood pressure in the leg suggests blocked arteries due to peripheral artery disease (PAD). (See "Clinical features, diagnosis, and natural history of lower extremity peripheral artery disease"and "Overview of thoracic outlet syndromes"and "Clinical manifestations and diagnosis of the Raynaud phenomenon"and "Clinical evaluation of abdominal aortic aneurysm".). Standards of medical care in diabetes--2008. Toe-brachial indexThe toe-brachial index (TBI) is a more reliable indicator of limb perfusion in patients with diabetes because the small vessels of the toes are frequently spared from medial calcification. Normal SBP is expected to be higher in the ankles than in the arms because the blood pressure waveform amplifies as it travels distally from the heart (ie, higher SBP but lower diastolic blood. Physiologic tests include segmental limb pressures and the calculation of pressure index values (eg, ankle-brachial index, toe-brachial index, wrist-brachial index), exercise . This is the systolic blood pressure of the ankle. The distal radial artery, princeps pollicis artery, deep palmar arch, superficial palmar arch, and digital arteries are selectively imaged on the basis of the clinical indication ( Figs. Diagnosis and management of occlusive peripheral arterial disease. Muscle Anatomy. Severe claudication can be defined as an inability to complete the treadmill exercise due to leg symptoms and post-exercise ankle systolic pressures below 50 mmHg. It is therefore most convenient to obtain these studies early in the morning. Medical treatment of peripheral arterial disease and claudication. Circulation 2005; 112:3501. PURPOSE: To determine the presence, severity, and general location of peripheral arterial occlusive disease in the upper extremities. The Doppler signals are typically acquired at the radial artery. Prior to the performance of the vascular study, there are certain questions that the examiner should ask the patient and specific physical observations that might help conduct the examination and arrive at a diagnosis. B-mode imaging is the primary modality for evaluating and following aneurysmal disease, while duplex scanning is used to define the site and severity of vascular obstruction. Brachial artery PSVs range from 50 to 100cm/s. The blood pressure is measured at the ankle and the arm (brachial artery) and the ratio calculated. The relationship between calf blood flow and ankle blood pressure in patients with intermittent claudication. With arterial occlusion, proximal Doppler waveforms show a high-resistance pattern often with decreased PSVs (see Fig. The quality of the arterial signal can be described as triphasic (like the heartbeat), biphasic (bum-bum), or monophasic. Accurate measurements of Doppler shift and, therefore, velocity measurements require proper positioning of the ultrasound probe relative to the direction of flow. OTHER IMAGINGContrast arteriography remains the gold standard for vascular imaging and, under some circumstances (eg, acute ischemia), is the primary imaging modality because it offers the benefit of potential simultaneous intervention. Two ultrasound modes are routinely used in vascular imaging: the B (brightness) mode and the Doppler mode (B mode imaging + Doppler flow detection = duplex ultrasound). An ABI of 0.9 or less is the threshold for confirming lower-extremity PAD. Analogous to the ankle and wrist pressure measurements, the toe cuff is inflated until the PPG waveform flattens and then the cuff is slowly deflated. Ota H, Takase K, Igarashi K, et al. (B) The Doppler waveforms are triphasic but the amount of diastolic flow is very variable. High ABIA potential source of error with the ABI is that calcified vessels may not compress normally, thereby resulting in falsely elevated pressure measurements. J Am Coll Cardiol 2001; 37:1381. The axillary artery dives deeply, and at this point, the arm is raised and the probe is repositioned in the axilla to examine the axillary artery. AbuRahma AF, Khan S, Robinson PA. This form of exercise has been verified against treadmill testing as accurate for detecting claudication and PAD. These criteria can also be used for the upper extremity. A pulse Doppler also permits localization of Doppler shifts induced by moving objects (red blood cells). PAD can cause leg pain when walking. B-mode imagingThe B-mode provides a grey scale image useful for evaluating anatomic detail (picture 4). Here are the patient education articles that are relevant to this topic. Noninvasive localization of arterial occlusive disease: a comparison of segmental Doppler pressures and arterial duplex mapping. Vascular Clinical Trialists. %PDF-1.6 % Patients can be asymptomatic, have classic symptoms of peripheral artery disease (PAD) such as claudication, or more atypical symptoms. If the high-thigh pressure is normal but the low-thigh pressure is decreased, the lesion is in the superficial femoral artery. 13.14B ) should be obtained from all digits. Alterations in the pulse volume contour and amplitude indicate proximal arterial obstruction. For patients who cannot exercise, reactive hyperemia testing or the administration of pharmacologic agents such as papaverineor nitroglycerinare alternatives testing methods to imitate the physiologic effect of exercise (vasodilation) and unmask a significant stenosis. Relleno Facial. Nicola SP, Viechtbauer W, Kruidenier LM, et al. The principal anthropometry measures are the upper arm length, the triceps skin fold (TSF), and the (mid-)upper arm circumference ((M)UAC).The derived measures include the (mid-)upper arm muscle area ((M)UAMA), the (mid-)upper arm fat area ((M)UAFA), and the arm fat index. (A) Gray-scale sonography provides a direct view of a stenosis at the origin of the right subclavian artery (, Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window), Click to share on Google+ (Opens in new window), on Assessment of Upper Extremity Arterial Disease, Assessment of Upper Extremity Arterial Disease, Assessment of Upper Extremity Arterial Occlusive Disease, Carotid Occlusion, Unusual Pathologies, and Difficult Carotid Cases, Ultrasound Evaluation Before and After Hemodialysis Access, Extremity Venous Anatomy and Technique for Ultrasound Examination, Doppler Ultrasound of the Mesenteric Vasculature. Obtaining the blood pressure in these two locations allows your doctor to perform an ankle-brachial index calculation that shows whether or not you have reduced blood flow in your legs. The tibial arteries can also be evaluated. It can be performed in conjunction with ultrasound for better results. Lower extremity segmental pressuresThe patient is placed in a supine position and rested for 15 minutes. However, the examination is expensive and also involves radiation exposure and the intravenous contrast agents. (See 'Segmental pressures'above.). The pressure drop caused by the obstruction causes the subclavian artery to be supplied by the ipsilateral vertebral artery. calculate the ankle-brachial index at the dorsalis pedis position a. The test is performed with a simple handheld Doppler and a blood pressure cuff, taking. INFORMATION FOR PATIENTSUpToDate offers two types of patient education materials, The Basics and Beyond the Basics. The Basics patient education pieces are written in plain language, at the 5thto 6thgrade reading level, and they answer the four or five key questions a patient might have about a given condition. Most, or sometimes all, of the arteries in the arm can be imaged with transducers set at frequencies between 8 and 15MHz. The natural history of patients with claudication with toe pressures of 40 mm Hg or less. The right arm shows normal pressures and pulse volume recording (, Hemodynamically significant stenosis. The subclavian artery continues to the lateral edge of the first rib where it becomes the axillary artery. The radial or ulnar arteries may have a supranormal wrist-brachial index. A continuous wave hand held Doppler unit is used to detect the brachial and distal posterior tibial and dorsalis pedis pulses and the blood pressure is measured using blood pressure cuffs and a conventional sphygmomanometer. Different velocity waveforms are obtained depending upon whether the probe is proximal or distal to a stenosis. Steps for calculating ankle-brachial indices include, 1) determine the highest brachial pressure, 2) determine the highest ankle pressure for each leg, and 3) divide the highest ankle pressure on each side by the highest overall brachial pressure. Calculation of the ankle-brachial index (ABI) at the bedside is usually performed with a continuous-wave Doppler probe (picture 1). Although progression of focal atherosclerosis or acute arterial emboli are almost always the cause of symptomatic disease in the lower extremity, upper extremity arterial disease is more complex. If the patient develops symptoms with walking on the treadmill and does not have a corresponding decrease in ankle pressure, arterial obstruction as the cause of symptoms is essentially ruled out and the clinician should seek other causes for the leg symptoms. ULTRASOUNDUltrasound is the mainstay for noninvasive vascular imaging with each mode (eg, B-mode, duplex) providing specific information. Signs [ edit ] Pallor Diminished pulses (distal to the fistula) Necrosis [1] Decreased wrist- brachial index (ratio of blood pressure measured in the wrist and the blood pressure [en.wikipedia.org] It is commoner on the left side with L:R ratio of ~3:1. ipsilateral upper limb weak or absent pulse decreased systolic blood pressure in the . Rofsky NM, Adelman MA. The disadvantage of using continuous wave Doppler is a lack of sensitivity at extremely low pressures where it may be difficult to distinguish arterial from venous flow. Interpreting ABI measurements: Normal values defined as 1.00 to 1.40; abnormal values defined as 0.90 or less (i.e. A blood pressure difference of more than 20mm Hg between arms is a specific indicator of a hemodynamic significant lesion on the side with the lower pressure. Did the pain or discomfort come on suddenly or slowly? ), In a prospective study among nearly 1500 women, 5.5 percent had an ABI of <0.9, 67/82 of whom had no symptoms consistent with peripheral artery disease. With a fixed routine, patients are exercised with the treadmill at a constant speed with no change in the incline of the treadmill over the course of the study. This chapter provides the basics of upper extremity arterial assessment including: The appropriate ultrasound imaging technique, An overview of the pathologies that might be encountered. The anatomy as shown in this chapter is sufficient to perform a comprehensive examination of the upper extremity arteries. Circulation 1995; 92:720. Mechanical compression in the thoracic outlet region, vasospasm of the digital arteries, trauma-related thrombi in the hand or wrist, arteritis, and emboli from the heart or from proximal arm aneurysms are pathologies to be considered when evaluating the upper extremity arteries. Screening for asymptomatic PAD is discussed elsewhere. This study aimed to assess the association of high ABPI ( 1.4) with cardiovascular events in people with peripheral artery disease (PAD). LEARNING OBJECTIVES/OUTCOMES After completing this continuing education activity, the participant will: 1. A variety of noninvasive examinations are available to assess the presence, extent, and severity of arterial disease and help to inform decisions about revascularization. 13.18 . The ankle-brachial index test is a quick, simple way to check for peripheral artery disease (PAD). Facial Esthetics. A normal value at the foot is 60 mmHg and a normal chest/foot ratio is 0.9. The stenosis is generally seen in the most proximal segment of the subclavian artery, just beyond the bifurcation of the innominate artery into the right common carotid and subclavian arteries. TBI is a common vascular physiologic assessment test taken to determine the existence and severity of peripheral arterial disease (PAD) in the lower extremities. 13.18 ). The walking distance, time to the onset of pain, and nature of any symptoms are recorded. Environmental and muscular effects. Screen patients who have risk factors for PAD. Aortoiliac Aortoiliac imaging requires the patient to fast for about 12 hours to reduce interference by bowel gas. Introduction to Measuring the Ankle Brachial Index ), For patients with an ABI >1.3, the toe-brachial index (TBI) and pulse volume recordings (PVRs) should be performed. %%EOF Both B-mode and Doppler mode take advantage of pulsed sound waves. Radiology 2000; 214:325. It is generally accepted that in the absence of diabetes and tissue edema, wounds are likely to heal if oxygen tension is greater than 40 mmHg. (See 'Toe-brachial index'below and 'Pulse volume recordings'below. 5. With severe disease, the amplitude of the waveform is blunted (picture 3). The pulse volume recording (. This observation may be an appropriate stopping point, especially if the referring physician only needs to rule out major, limb-threatening disease or to make sure there is no inflow disease before coronary artery bypass surgery with the internal thoracic artery (a branch of the subclavian artery; see Fig. If a patient has a significant difference in arm blood pressures (20mm Hg, as observed during the segmental pressure/PVR portion of the study), the duplex imaging examination should be expanded to check for vertebral to subclavian steal. Indications involved soft-tissue coverage of the elbow (n = 11), dorsal wrist and hand (n = 24), palmar wrist and hand (n = 12), and thumb amputations (n = 5); after release of thumb-index finger . The Ankle Brachial Index (ABI) is a measure of ankle pressure divided by the pressure at the arm. As with low ABI, abnormally high ABI (>1.3) is also associated with higher cardiovascular risk [22,27]. In this video, taken from our Ultrasound Masterclass: Arteries of the Legs course, you will understand both the audible and analog waveforms of Dopplers, and. Ann Surg 1984; 200:159. 9. Circulation 1995; 92:614. Does exposure to cold or stressful situations bring on or intensify symptoms? Hirsch AT, Haskal ZJ, Hertzer NR, et al. Color Doppler ultrasound is used to identify blood flow within the vessels and to give the examiner an idea of the velocity and direction of blood flow. The quality of a B-mode image depends upon the strength of the returning sound waves (echoes). CT and MR imaging are important alternative methods for vascular assessment; however, the cost and the time necessary for these studies limit their use for routine testing [2]. Menke J, Larsen J. Meta-analysis: Accuracy of contrast-enhanced magnetic resonance angiography for assessing steno-occlusions in peripheral arterial disease. Physiologic tests include segmental limb pressures and the calculation of pressure index values (eg, ankle-brachial index, wrist-brachial index), exercise testing, segmental volume plethysmography, transcutaneous oxygen measurements and photoplethysmography. (A) The radial artery courses laterally and tends to be relatively superficial. These tools include: Continuous-wave Doppler (with a recording device to display arterial waveforms), Pulse volume recordings (PVRs) and segmental pressures, Photoplethysmographic (PPG) sensors to detect blood flow in the digits. Sign in|Recent Site Activity|Report Abuse|Print Page|Powered By Google Sites. Finger Pressure Digit-Brachial Index (DBI) is the upper extremity equivalent of the lower extremity Ankle-Brachial Index. Deep palmar arch examination. The level of TcPO2that indicates tissue healing remains controversial. If the problem is positional, a baseline PPG study should be done, followed by waveforms obtained with the arm in different positions. 13.5 and 13.6 ), radial, and ulnar ( Fig.