Performing a Vascular Assessment
The vascular system is comprised of vessels that move blood and lymph throughout the body. This includes the arteries, arterioles, capillaries, venules and veins. Much of your vascular assessment will be evaluating arterial function, since it’s the arteries that deliver oxygenated blood to the tissues.
Before we dive into vascular assessment, let’s review a few key terms:
- Ischemia – Inadequate blood supply to an organ or tissue
- Hypoxia – Inadequate oxygen at the tissue level
- Necrosis – Death of tissue
- Infarct – An area of necrosis due to inadequate blood supply
- Bruit – An abnormal sound heard over an area of turbulent blood flow
- Thrill – A soft vibration felt on the skin overlying area of turbulent blood flow such as an AV fistula or significant cardiac murmur
When are vascular assessments conducted?
It’s important to understand that, in most cases, what you are ultimately assessing with vascular assessment is tissue perfusion. For example, if you can’t locate a pulse on your patient’s left foot, how well do you think that foot is being perfused? If capillary refill is delayed, what does that tell you about tissue perfusion?
Note that sometimes your vascular assessment will be focused on veins if the patient has venous insufficiency or varicose veins, but for the most part we’re looking at blood flow through the arterial side of circulation.
With that said, a basic vascular assessment is conducted on every patient when you check a blood pressure, palpate the radial pulse and check capillary refill as part of your general head-to-toe assessment. Vascular assessments are also conducted in many other clinical scenarios, including:
- The patient has known or suspected peripheral vascular disease
- The patient has known or suspected DVT
- The patient has undergone treatment or surgery for an arterial issue (such as removing a blood clot)
- The patient has had any type of vascular surgery
- The patient has an A/V fistula or graft
- The patient has had an artery punctured such as with a left-sided heart catheterization
- The patient has compromised hemodynamics
Blood Pressure Measurement
To ensure a proper blood pressure measurement, it’s important to ensure you have the appropriate size cuff. A cuff that is too large will provide a falsely low reading, while a cuff that is too small will provide a falsely elevated reading. Disposable cuffs typically have markings on them to indicate sizing. If you do need use measurements, the width of the bladder should be 40% of the arm circumference and the length of the bladder should cover 80% of the arm from elbow to shoulder.
Some more tips for accurate blood pressure measurement include:
- Position the patient optimally, which is seated with the arm supported at heart level. In the clinical setting, you’ll often be measuring while the patient is in bed. If you can’t adjust the HOB, be sure to chart which position the patient was in at the time of measurement.
- Ask the patient to be still and quiet during the reading.
- If a reading doesn’t make sense (based on trends or the patient’s clinical presentation), check that the cuff is applied properly and re-measure.
- To be thorough, check blood pressure in both arms, noting that a slightly higher reading on the right is not uncommon.
Pulses are assessed via palpation or, when that fails, via a Doppler device. The most common pulses assessed in the clinical setting are the radial, dorsalis pedis, and posterior tibial. In a code or in cases where hemodynamics are severely compromised, the femoral artery and carotid artery are used because they are closer to the heart and more likely to have a palpable pulsation.
Pulses are graded based on their strength:
- 0 = absent (no pulse obtainable through palpation or Doppler)
- 1 = diminished
- 2 = normal
- 3 = bounding
If a patient’s pulses are difficult to obtain via palpation or you are using a Doppler, always mark the pulse location with a permanent marker so they’re easy to locate for future assessments.
General assessment of peripheral vasculature
- Measure capillary refill by compressing the nail bed until the tissue blanches and then release. Count the number of seconds it takes for the tissue to return to its original color. Capillary refill is considered delayed if this takes longer than three seconds and tells us that tissue perfusion is compromised.
- Assess for pitting edema which may be present bilaterally in venous insufficiency and unilaterally in DVT. Press on the area with your fingers and observe the depth of the temporary indentation. Pitting edema is graded as +1 to +4, with +4 being the most severe and indicating an indentation of about 8 mm.
- Assess color of the extremities. Abnormal color findings include pallor, rubor, mottling, cyanosis, and black or necrotic (due to dry gangrene secondary to arterial insufficiency).
- Assess temperature of the extremities. When blood flow is inadequate, extremities are often cool (especially hands and feet). When no blood flow is present, the affected area will be cold.
- Observe for any skin abnormalities such as lesions or ulcers which can occur due to venous or arterial insufficiency and even the presence of underlying AVMs.
- Assess the veins for varicosities and other abnormalities. Varicose veins are common in pregnant individuals and those who stand or sit for long periods of time. If the vein is pulsating, this could be an AVM…do not palpate it and make sure the MD is aware. With thrombophlebitis, the patient may complain of an aching pain and there will be swelling and even firmness over the affected vein.
- Assess for pain which may be present with both arterial and venous disorders. The pain associated with arterial disorders is more intense and may be relieved by rest. The pain with venous disorders is more dull and often described as “heaviness” in the legs.
A basic neurovascular assessment includes circulation, sensation and movement (CSM).
- Circulation is assessed by palpating the pulse (or using a Doppler) and by assessing capillary refill, skin color and skin temperature.
- Sensation is assessed by asking the patient if they have numbness and tingling, and if they can feel when you touch them.
- Movement is assessed by asking the patient to move the extremity.
The 6 P’s of Ischemia
When blood flow to an extremity is significantly reduced or absent the patient will experience ischemia. The “Six Ps of ischemia” can help you recognize this abnormal clinical finding:
- Pain – can be severe and often described as sharp or burning
- Pulselessness – absence of a pulse (make sure to attempt a Doppler pulse before claiming a pulse is absent!)
- Pallor – the area distal to the interrupted blood flow will be pale
- Poikilothermia – the area will lack the ability to maintain body temperature (it will be cool or cold)
- Paresthesia – the patient will have numbness and tingling
- Paralysis – the patient will not be able to move the affected area
Performing an Allen Test
An Allen test is conducted prior to the puncture of the radial artery, such as when an ABG specimen is obtained or an arterial line is placed. The test is performed to ensure the hand has adequate flow through the ulnar artery in case the radial artery is damaged by the procedure.
To perform an Allen test, ask the patient to clench their first or close it tightly for them if they are unable to participate. Occlude both the radial and ulnar arteries, which obstructs blood flow to the hand. While maintaining the pressure, ask the patient to relax the hand while you observe if the palm and fingers have blanched. If they haven’t, then the hand is still getting blood flow and you haven’t occluded the arteries adequately. Re-occlude until the hand and fingers blanch. Next, release pressure from the ulnar artery and observe for improved perfusion in the fingers and hand. The test is positive if the hand flushes within 5 to 15 seconds, indicating good ulnar blood flow. If the test is negative, the radial artery should not be punctured.
Bruits and Thrills
A bruit is an abnormal sound that occurs over areas of turbulent blood flow. Sometimes they’re expected (as with an AV fistula or graft) but they can also be pathological (as with a carotid bruit).
To assess for a bruit in the carotid arteries, ask the patient to hold their breath as you listen through your stethoscope to the blood flow through each artery. The presence of a bruit in a carotid artery is suggestive of carotid stenosis and the patient may be at risk for stroke. This is an abnormal finding that should be relayed to the MD.
To assess for a bruit in the AV fistula or graft, place your stethoscope on the skin and listen for the turbulence. You can also feel for the turbulent blood flow with gentle palpation…the “thrill” will feel like a vibration under the skin. If you are unable to hear the bruit or feel the thrill, this is an abnormal finding and the MD should be notified.
Other locations where you can listen for bruits are the temporal arteries, the aortic artery, the renal arteries, and the iliac and femoral arteries. Always remember to have the patient hold their breath while you listen.
Since the vascular system is so reliant on cardiac output, you might want to learn more about cardiac assessment here.
Review vascular assessments again while you’re on the go in episode 274 of the Straight A Nursing podcast. Tune in wherever you get your podcast fix, or straight from the website here.
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