Physiologic Exams Flashcards
A patient presents with HTN, DM and left lower extremity pain that occurs only as he walks. He usually begins to have pain after he walks to his mailbox with increasing pain as he returns to the house. The pain is relieved by resting his legs for a few minutes. What would the predicted ABI value be for the left leg?
A. 0.9
B. 0.6
C. 0.4
D. above 1.0; these symptoms are most likely unrelated to arterial disease
B
The patient is experiencing claudication which is found in patients with 0.5 - 0.9 ABI. The short distance of walking to the mailbox before the pain begins indicates a more significant amount of disease than 0.9 ABI would indicate. An ABI of 0.6 is the best choice with the given symptoms.
Which of the following is a characteristic of a normal arterial PPG waveform? A. low amplitude B. slow downslope C. prominent dicrotic notch D. slow upslope
C
An abnormal PPG waveform will demonstrate a loss of the dicrotic notch, slow upslope, slow downslope and little difference between systolic and diastolic blood volumes.
A patient presents with left lower extremity pain that awakens him at night. The pain is relieved by sitting at the side of the bed for a few minutes. What would the predicted ABI value be for the left leg?
A. 0.8
B. 0.6
C. 0.4
D. above 1.0; these symptoms are most likely unrelated to arterial disease
C
The patient is experiencing rest pain which is found in patients with an ABI less than 0.5.
If the blood pressure in the ankle is obtained with the patient’s legs in the dependent position:
A. the pressure will be underestimated
B. the ankle will demonstrate the same response as if an exercise exam was just performed
C. the pressure will be falsely elevated
D. it will be the same as if the patient is evaluated in the supine position
C
If the blood pressure in the ankle is obtained with the patient’s legs in the dependent position, the pressure will be falsely elevated due to the effects of hydrostatic pressure.
Lower extremity arterial segmental pressure exam results in a post exercise basal pressure recovery time of 2 to 6 minutes which suggests: A. multi-level stenosis B. iliac disease C. single level stenosis D. thoracic outlet syndrome
C
Lower extremity arterial segmental pressure exam resulting in a post exercise basal pressure recovery time of 2 to 6 minutes suggests single level disease. Lower extremity arterial doppler exam resulting in a post exercise basal pressure recovery time greater than 6 minutes suggests multi-level disease.
When performing post-occlusive reactive hyperemia, pressure measurements in the lower extremities are obtained:
A. immediately after cuff release and every 2 minutes until pressures return to baseline levels
B. 1 minute after cuff release and every 2 minutes until pressures return to baseline levels
C. 1 minute after cuff release and every 30 seconds until pressures return to baseline levels
D. immediately after cuff release and every 30 seconds until pressures return to baseline levels
D
When performing post-occlusive reactive hyperemia of the lower extremities, pressure measurements are obtained immediately after cuff release and every 30 seconds until pressures return to baseline levels. Recovery time is shorter for reactive hyperemia than treadmill testing.
A 65yr old male presents with mild left calf pain after walking 10 blocks. The pain is relieved by sitting and resting. On a resting arterial exam with ABI, the left ABI is 1.04. These findings are most suggestive of:
A. the venous system should be evaluated for possible insufficiency
B. an exercise arterial should be performed to re-evaluate the ABI of the left leg before a diagnosis is made
C. the venous system should be evaluated for thrombosis
D. the patient is most likely experiencing an orthopedic or neurogenic problem and an MRI may be warranted
B
Because the symptoms occur when the patient is walking, the leg should be elevated with exercise to completely rule out a vascular diagnosis.
Pulse volume recording:
A. will demonstrate waveforms that are nearly identical to the analog Doppler waveforms in a normal patient
B. readings should be taken beginning with the distal cuff and moving proximally
C. is used to assess arterial insufficiency and DVT
D. is commonly performed with a segmental pressure exam
D
Pulse volume recording is used to assess arterial and venous insufficiency, not DVT. PVR exams are usually performed with segmental pressure exams. Readings are taken first in the proximal extremity and then moving distally to the next cuff. The normal waveform will be monophasic with rapid upstroke, sharp systolic peak, prolonged downstroke and prominent reflection (dicrotic notch). Normal Doppler tracings would be triphasic.
When performing a photoplethysmography exam for venous insufficiency, where should you place the sensor? A. distal pad of the great toe B. dorsal aspect of the great toe C. medial distal calf D. groin
C
Venous insufficiency is assessed by placing the sensor on the distal calf. Arterial disease is assessed by placing the sensor on the pads of the toes.
Which of the following patients would benefit from an exercise segmental pressure exam?
A. patient with claudication and resting ABI 0.6
B. patient with COPD and resting ABI of 0.9
C. patient with claudication and a resting ABI of 0.95
D. patient with rest pain and resting ABI 0.4
C
A normal resting ABI can become abnormal with exercise in patients with less severe disease. The patient with COPD would most likely be recommended for reactive hyperemia. An ABI that is less than 0.9 demonstrates PAD is present. The exercise exam will not provide any additional information to assist on the diagnosis of these patients.
Upon cessation of exercise, the ankle pressures in a normal patient will:
A. increase to normal levels in less than 5 minutes
B. increase to normal levels in less than 10 minutes
C. decrease to normal levels in less than 10 minutes
D. decrease to normal levels in less than 5 minutes
D
Upon cessation of exercise, the ankle pressures to normal levels within 5 minutes. Ankle and arm pressures should show a mild increase with exercise. Because they increase at relatively the same levels, the ABI usually stay the same or increases slightly.
A patient presents with HTN, DM and left lower extremity pain that worsens as he walks. He usually begins to have pain after he walks to his mailbox with increasing pain as he returns to the house. The pain is relieved by resting his leg for a few minutes. A bilateral resting ABI is performed with the right leg, 1.12 and the left leg 1.34. Which of the following statements is true regarding the findings?
A. medial calcification of the left calf vessels is most likely present
B. these symptoms are most likely unrelated to arterial disease
C. the patient should be evaluated for popliteal entrapment in the left leg
D. hypertension disease usually leads to overestimation of the ABI values
A
Patients with diabetes have increased incidence of medial calcification of the extremity vessels which causes falsely increased ABI measurements. An ABI over 1.30 usually indicates the presence of medial calcification.
Which of the following will increase the amplitude of a digital PPG tracing?
A. warming the patients foot and toes
B. adding more gel between the skin and the sensor
C. increase sweep speed of the recorder
D. adjust the baseline of the tracing
A
PPG exams should be performed in a warm room. The digits can be warmed to increase pulse amplitude. A towel can be used to cover the digits and sensors to warm the digits and reduce effects of surrounding light. The sweep speed effects the display of volume changes over time, not amplitude of the tracing. The baseline is used to indicate positive or negative direction of flow. Changes in baseline are used to highlight flow patterns toward or away from the transducer.
Which of the following is a reason to perform exercise with a segmental pressure exam?
A. to differentiate an SFA stenosis from an occlusion
B. to evaluate volume changes in the limb
C. to differentiate true claudication from pseudoclaudication
D. to evaluate the effects of vasoconstriction
C
True claudication will be associated with a decrease in ABI with exercise. Pseudoclaudication will be associated with no change in the ABI with exercise.
What can be done to inhibit light from the exam room from causing artifact on an upper extremity PPG tracing?
A. cover the patient’s hand with a towel or sheet
B. perform the exam with all lights off and windows covered
C. increase the room temperature
D. place acoustic gel between the PPG sensor and the skin
A
To reduce light from the exam room from causing artifact on the PPG tracing, cover the patient’s hand with a towel or sheet.
A patient presents with left leg claudication. The right ABI is 1.13 and the left ABI is 1.37. What should you do next for this patient?
A. put the patient on the treadmill and repeat the ABI for both legs
B. end the exam and record the findings
C. stop the segmental pressure exam and obtain toe pressures along with PVR waveforms
D. switch to 16cm thigh cuffs and continue the segmental exam to include the proximal calf and thigh pressures
C
When the ABI exceeds 1.3, there is most likely medial calcification present. Because medial calcification does not usually affect the smaller digital arteries, the toe pressures can be obtained. PVR waveforms can be obtained to locate the obstruction, if the TBI is abnormal.
Which of the following is not proper procedure for a venous PPG evaluation of the legs?
A. patient is seated with legs dangling over edge of bed for the exam
B. Always place the sensor over the largest varicose vein in the calf
C. the optimal speed for the strip chart recorder is 5mm/sec
D. a tourniquet is applied to the leg after initial testing shows a VRT < 20 sec
B
Patient is seated with legs dangling over edge of bed for the exam. A sensor is placed on the distal medial lower leg. Never place the PPG sensor on an open wound, ulcer or varicose vein. A strip chart recorder documents flow changes. The optimal speed for the strip chart recorder is 5mm/sec. A tourniquet is applied to the leg after initial testing shows a VRT < 20 sec.
When performing an upper extremity segmental pressure exam, you obtain the following reading on the right arm. Right upper arm 140mmHg, right radial artery 110mmHg, right ulnar artery 130mmHg. Which of the following correctly explains the findings? A. subclavian artery obstruction B. radial artery disease C. distal brachial artery obstruction D. radial and ulnar artery disease
B
There is a 30mmHg drop in pressure between the upper arm and the radial artery at the forearm. This indicates radial artery disease. The ulnar artery pressure is only mildly decreased and does not indicate disease. A brachial obstruction would affect the pressure in both of the forearm arteries.
The following pressure readings from a segmental pressure evaluation were obtained in a patient suffering from low back and thigh pain. What is the ABI for each leg?
Lt Ankle 136
Rt Ankle 128
Lt Arm 124
Rt Arm 120
A. Rt = 1.03, Lt = 1.10
B. Rt = 1.03, Lt = 1.13
C. Rt = 1.07, Lt = 1.10
D. Rt = 0.94, Lt = 0.91
A
Rt ABI = 128/124 = 1.03
Lt ABI = 136/124 = 1.10
The following pressure readings from a segmental pressure evaluation were obtained in a patient suffering from low back an thigh pain when walking. Which of the following describes a possible reason for the patient’s symptoms?
Lt Ankle 136
Rt Ankle 128
Lt Arm 124
Rt Arm 120
A. neurogenic claudication
B. stenosis of the external iliac artery
C. May Thurner syndrome
D. stenosis of the common femoral artery
A
When lower extremity symptoms are caused by ambulation and the ABI exam is normal, the symptoms are called pseudoclaudication or neurogenic claudication. The most common cause of pseudoclaudication due to lumbar spinal stenosis, a condition that occurs when the spaces narrow between the vertebrae in your lower back.
A diabetic patient presents for a segmental pressure exam. The patient complains of an injury to his big toe that won't seem to heal and has been open for over 3 weeks. The digital pressure in the affected toe will most likely be \_\_\_\_\_\_\_. A. <30mmHg B. 60-90mmHg C. >200mmHg D. 30-60mmHg
A
Toe pressures <30mmHg correlate with a non-healing wound.
A patient comes in late for his scheduled exam and states he walked to the facility after his car broke down. Registration passes him through to the vascular department and he is still slightly SOB. What is the first thing you should do when starting his exam?
A. take his brachial pressures
B. have him lie down and start with the Duplex exam and perform the pressures later
C. Take his ankle pressures using the PTA and DPA
D. have him rest for 20-30 minutes to allow flow in the legs to normalize
D
If the patient does not rest, the exercise from his long walk can affect the results of the expected resting arterial exam. This can lead to overestimation of the severity of the disease identified on the resting exam.
It is important to wait at least one minute before repeating what measurement?
A. brachial pressure on an arm with a hemodialysis graft
B. volume flow in a hemodialysis graft
C. ankle blood pressure
D. MCA mean velocity
C
When you are obtaining a blood pressure for a second time, it is important to wait at least 1 minute between cuff inflations. Pressure results may be inaccurate if the system is not given the opportunity to normalize after the first pressure measurement. NEVER perform a blood pressure assessment on an arm with a hemodialysis graft.
What are the average treadmill settings utilized in exercise testing? A. 5mph at 10% grade B. 2mph at 12% grade C. 3mph at 8% grade D. 5mph at 12% grade
B
The average treadmill settings utilized in exercise testing is 2mph speed at 12% grade.
When evaluating suspected thoracic outlet syndrome, a PPG exam can be performed with the sensor placed on the \_\_\_\_\_\_\_\_ or a Doppler exam can be performed with the transducer placed \_\_\_\_\_\_\_\_\_\_. A. lateral wrist, on the brachial artery B. 2nd digit, on the radial artery C. 1st digit, on the carotid artery D. medial wrist, on the radial artery
B
When evaluating suspected thoracic outlet syndrome, a PPG exam can be performed with the sensor placed on the 2nd digit or a Doppler exam can be performed with the transducer placed on the radial artery.
Lower extremity arterial segmental pressure exam results in a post exercise basal pressure recovery time of > 6 minutes which suggests: A. popliteal entrapment syndrome B. single level stenosis C. iliac disease D. multi-level stenosis
D
Lower extremity arterial segmental pressure exam resulting in a post exercise basal pressure recovery time of 2 to 6 minutes suggests single level disease. Lower extremity arterial Doppler exam resulting is a post exercise basal pressure recovery time greater than 6 minutes suggests multi-level disease.
Which of the following is NOT an appropriate reason to terminate the treadmill exercise for a lower extremity arterial exam?
A. patient complains of chest pain
B. patient complains that the treadmill is too noisy
C. patient complains of shortness of breath
D. patient complains of leg pain
B
Anytime the patient reports symptoms of pain in the legs or the chest, the exam should be terminated. Never try to talk the patient into continuing the exam. Always record the duration of the exercise, location of the symptoms and changes in ankle pressures.
A normal extremity arterial response to reactive hyperemia is:
A. <35% increase in ankle pressures that return to normal within one minute
B. no change is ankle pressures
C. <50% drop in ankle pressures
D. <35% drop in ankle pressures that return to normal within 1 minute
D
A normal lower extremity arterial response to reactive hyperemia is <35% drop in ankle pressures that return to normal within 1 minute.
Which of the following describes an Air Plethysmography exam that is positive for venous insufficiency?
A. after the patient performs 40 toe raises, the venous filling index will decrease under the cuff
B. after the legs are elevate and then the patient stands, the venous filling index will be increased
C. recording demonstrates large changes in blood volume in the area of the leg under the cuff
D. APG is not performed to assess venous insufficiency
B
An APG exam is performed by placing a large cuff around the calf. The leg is elevated until the plethysmographic tracing plateaus indicating the veins have emptied. The patient will then quickly stand up to assess the rate of venous refill under the cuff. A fast refill time occurs with valvular insufficiency. A VRT greater than 20 seconds is considered normal. The venous refill index is measured in mL/sec. VFI = 90% venous refill volume divided by time it took to reach 90% volume. Slower refill rates are normal. VFI <2mL/sec is normal; >7mL/sec indicates severe insufficiency.
The 12cm blood pressure cuffs are missing from the lab. You perform the 3 cuff method lower extremity segmental pressure exam with the 10cm cuffs on a patient that is 5’5” 150lbs. What information that you will report will be invalid?
A. calf pressure only
B. brachial pressure, calf pressure and ankle pressure
C. brachial pressure only
D. thigh pressure only
D
The 12cm cuff is normally used for the thigh. If the smaller cuff is used, the pressure will be overestimated in the thigh.
Which of the following is a normal response from the capillary beds of the feet and ankles after 5 minutes of vigorous exercise?
A. vasoconstriction
B. increased osmotic pressures
C. no change in the flow in normal vessels
D. vasodilation
D
Resistance decreases in the capillary beds to allow an increase in flow volume with exercise. Normal arteries do not demonstrate any change in pressure with exercise.
When performing a treadmill test for PAD, exercise is normally performed ______. When performing a reactive hyperemia exam for PAD, the cuffs are inflated ________.
A. with the patient standing, with the patient supine
B. with the patient supine, with the patient standing
C. for up to 5 minutes, for up to 5 minutes
D. for up to 10 minutes, for up to 5 minutes
C
When performing a treadmill test for PAD, exercise is normally performed for up to 5 minutes. When performing a reactive hyperemia exam for PAD, the cuffs are inflated for up to 5 minutes. If the patient experiences symptoms, the exam can be terminated earlier.
Which of the following is performed with the patient sitting upright? A. penile Doppler exam B. pressure evaluation of the toes C. PVR evaluation of the toes D. pressure evaluation of the fingers
D
Finger pressures should be obtained with the patient sitting upright, hand placed on a positioning wedge or pillow.
When performing a lower extremity venous Doppler for insufficiency,
A. the intensity of the Doppler signal indicates the severity of the reflux
B. augmentation pressure is applied quickly, held for at least 15 seconds, and released quickly
C. a minimum of 30 seconds between augmentation maneuvers is recommended
D. the GSV should be evaluated with patient bearing weight on the leg
C
When performing a lower extremity venous Doppler for insufficiency, a minimum of 30 seconds between augmentation maneuvers is recommended. The veins need sufficient time to refill before augmentation is repeated.
A patient presents with a history of HTN, DM and claudicaton. The arterial Doppler evaluation demonstrates monophasic flow in all vessels but the ABI values are LT 1.36 and RT 1.32. Which of the following correctly describes the findings?
A. the exam is normal and additional testing should be performed to rule out extrinsic vessel compression due to popliteal entrapment syndrome
B. the most likely diagnosis is thromboangiitis obliterans, which leads to medial calcification of the calf vessels
C. the exam is normal and additional testing should be performed to rule out extrinsic vessel compression due to median arcuate ligament syndrome
D. the ABI values are abnormally elevated due to a diabetic complication called medial calcification
D
Monophasic flow in the extremities is normally accompanied with an ABI less than 0.9. Diabetes can lead to medial calcification of the arterial walls which will falsely elevate the ankle pressures.
Which of the following screening techniques for peripheral arterial disease can distinguish between a stenosis and an occlusion in a vessel? A. segmental pressure evaluations B. Doppler evaluations C. pulse volume recording D. photoplethysmography
B
Segmental pressure and PVR exams can only detect the decrease in flow volume to the legs at a general location in the leg. The results do not provide information on specific vessels, nor can they distinguish stenosis from occlusion.
A segmental pressure exam demonstrates the following pressures; distal thigh 144, calf 166, ankle 132. Which of the following could explain these results?
A. medial calcification or venous insufficiency
B. incorrect cuff size would be the only possible cause
C. improper cuff placement and incorrect cuff size, but not medial calcification
D. incorrect cuff size, medial calcification and improper cuff placement
D
The calf pressure should not demonstrate an increased pressure related to the thigh pressure. All of the choices can lead to an overestimated pressure measurement.
When evaluating arterial pressures in the toes, the patient should be: A. standing B. sitting C. supine D. walking
C
Arterial pressures should be evaluated with the patient supine to eliminate the effects of hydrostatic pressure.
Which of the following is considered a limitation of the three cuff lower extremity segmental pressure exam?
A. the single thigh cuff normally overestimates the thigh pressure
B. there is no way to differentiate groin and ankle arterial disease
C. there is no way to differentiate lower thigh and popliteal arterial disease
D. there is no way to differentiate proximal and distal calf artery disease
C
Because there is only one cuff on the thigh, there is no way to differentiate disease in the lower thigh from disease in the popliteal artery. The pressure is obtained mid-thigh and calf. The distal SFA and popliteal artery could have disease if the calf pressure is decreased.
Where is the recommended placement for the pneumatic cuff when using a rapid cuff inflator to evaluate the distal femoral vein and great saphenous vein? A. distal thigh B. upper calf C. foot/metatarsals D. ankle
B
When evaluating a patient for insufficiency, a rapid cuff inflator can be used for a consistent augmentation of each vessel. The cuff is usually placed just distal to the area of interest. 70 to 80mmHg of pressure is applied quickly, held for a few seconds, and released quickly. Reversal of flow is assessed after release of the augmentation compression. Veins distal to the cuff can also be evaluated using proximal augmentation. Flow reversal would be documented during the compression part of the augmentation.
A patient complains of left arm numbness and pain that increases in severity when it is cold outside. An upper extremity arterial duplex exam demonstrates a >50% stenosis in the distal subclavian artery. The PPG exam demonstrates additional decrease in digital flow with cold exposure. What explains these findings? A. Buerger Disease B. Thoracic Outlet Syndrome C. Primary Raynaud Syndrome D. Secondary Raynaud Syndrome
D
Changes in flow patterns in the hand due to the application of external stimuli (cold) are a characteristic sign of Raynaud Disease. Secondary Raynaud Phenomenon refers to these changes that occur in conjunction with a diseased arterial system in the upper extremity. Primary Raynaud Syndrome refers to these changes that occur in conjunction with a non-diseased arterial system in the upper extremity.
Treadmill exercise is normally performed:
A. until symptoms are intolerable
B. up to 12 minutes or until symptoms are intolerable
C. up to 5 minutes
D. until symptoms are intolerable or up to 5 minutes
D
Treadmill exercise is normally performed until symptoms are intolerable or up to 5 minutes.
Venous PPG tracings are obtained. The right side demonstrates a venous refill time of 14 seconds. The left side demonstrates a refill time of 23 seconds. Which of the following describes the next step in evaluation?
A. a tourniquet will be applied to the left leg at the thigh level and the VRT assessment will be repeated
B. a tourniquet will be applied to the right leg at the thigh level and the VRT assessment will be repeated
C. a tourniquet will be applied to both legs at the thigh level and the VRT assessment will be repeated
D. the results are normal. No further evaluation is necessary.
B
The left side demonstrates a normal VRT > seconds. The right leg requires evaluation with a tourniquet. If the VRT returns to a level above 20 seconds, this indicates the insufficiency is in the superficial system. If the VRT remains abnormal with the superficial system “cut off” by the tourniquet, this indicates deep venous system insufficiency.
Photoplethysmography uses \_\_\_\_\_\_\_\_\_ to detect changes in venous volume in the leg. A. mercury tubing B. light C. sound waves D. air
B
Photoplethysmography uses light to detect changes in venous volume in the leg.
Which blood vessel is most commonly evaluated with Doppler to obtain the thigh pressure when performing a segmental pressure exam?
A. femoral artery just distal to the thigh cuff
B. distal calf artery with highest ankle pressure
C. distal calf artery with lowest ankle pressure
D. popliteal artery just above the calf cuff
B
The PTA or DPA that yields the highest pressure at the ankle should be used to obtain the pressures for the remaining arterial segments.
A patient presents with a history of recurrent upper extremity DVT due to Paget Schroetter syndrome. The referring physician ordered a PVR exam of the upper extremities instead of a venous Doppler exam of the upper extremities. Why?
A. to rule out associated atherosclerotic disease
B. to rule out Raynaud’s syndrome
C. to rule out a subclavian steal
D. to rule out thoracic outlet syndrome
D
Paget Schroetter syndrome is commonly associated with thoracic outlet syndrome. The presence of a cervical rib or aberrant muscle band can be involved with the DVT formation with Paget Schroetter syndrome.
A patient presents for an exercise arterial exam after an abnormal resting exam. The report for the resting exam describes: elevated velocities that indicate a stenosis of >50% in the distal femoral artery on the left leg, biphasic waveforms in the PTA and DPA and an ABI of 0.96. There is no change in the waveforms or decrease in ankle pressures in the left leg with exercise. What could explain these findings? A. obstructed venous outflow B. Raynaud syndrome C. congestive heart failure D. extensive collateral formation
D
Exercise induces peripheral vasodilation. If collateral flow is present, it will compensate for the expected drop in flow and pressure from a diseased vessel.
Which of the following would cause the systolic pressure reading obtained from the below knee cuff to be falsely elevated?
A. cuff is too large
B. cuff placement over the tibial tubercle
C. the patient suffers from congestive heart failure
D. reading obtained with the patient supine
B
The bladder of the cuff must be placed over the artery being evaluated and only compress soft tissue, not bony structures. The below-knee or upper calf cuff should be placed just distal to the tibial tubercle or pressure readings will be falsely elevated. Other causes of falsely elevated pressure readings include medial calcification, cuff too loose, cuff too small, patient not supine (hydrostatic pressure).
You are preparing for a lower extremity segmental pressure exam on a patient with leg pain. She was admitted to the hospital 2 days ago due to extensive lower extremity DVT. How will you proceed?
A. obtain Doppler waveforms and toe-brachial indices
B. check the chart for anticoagulant medication and if it is listed, proceed normally with the exam
C. cancel the exam
D. use cuffs only over areas of the leg where DVT was not identified
A
If a patient has suspected or known acute deep venous thrombosis, use waveform analysis only and/or use toe/brachial indices (TBI). Never place cuffs on a leg with DVT. You could easily cause and embolism with the cuff pressure. Anticoagulant therapy helps to prevent propagation of the clot, it does not provide thrombolytic therapy. The DVT found 2 days ago cannot have recanalized in such a short period of time. A Sonographer should never cancel and exam without referring physician approval.
The difference in systolic pressure between two adjacent levels in the same leg should be no more than \_\_\_\_\_\_\_\_mmHg. A. 15 B. 20 C. 25 D. 30
D
A drop in pressure of 30mmHg or more between segments indicates disease between the two segments.
