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Point of care ultrasound, or POCUS, can aid in the quick diagnosis and faster treatment of critical conditions such as vascular diseases, leading to decreased patient mortality. For learners, the anatomical difference between arteries and veins can also be better understood with the help of POCUS. Arteries are thicker walled and pulsatile; veins are thinner walled, may have valves, and collapse when compressed.
Arteries may be difficult to palpate if they are deeper, have reduced blood flow, or if a practitioner does not know the anatomic landmarks or is inexperienced. During an examination, while palpation enables an understanding of the intensity, symmetry, and rhythm of blood flow, POCUS can provide exact information on the underlying anatomy and location of the blood vessels. For example, the dorsalis pedis is a major artery that runs over the dorsal foot. It can become impalpable if the flow is obstructed. In such a condition, POCUS can help to detect the absence of blood flow.
Consider the internal jugular vein or IJV, which drains venous blood from the brain and superficial veins of the face and finally delivers the blood to the right atrium of the heart. Visualization of the internal jugular vein under ultrasound can improve the inspection of jugular venous distension.
Among the arteries, the aorta is the main artery that carries oxygenated blood from the heart and branches off to deliver blood to the rest of the body. The portion of the aorta that passes through the abdomen, from the diaphragm to the umbilical area, is known as the abdominal aorta. The abdominal aorta is examined using POCUS to diagnose life-threatening conditions such as abdominal aortic aneurysm— a swelling in the aorta, or aortic dissection— a tear in the artery.
The conceptual knowledge of the vascular system combined with the technical skills of using palpation and ultrasound can help make life-saving diagnoses during physical examination.
In this video, we will demonstrate how to use POCUS to facilitate learning the examination of veins and arteries.
The examination of peripheral arteries has been discussed in the previous JoVE video "Peripheral Vascular Exam".
Point of care ultrasound enables live imaging and identification of arteries and veins and therefore helps learners correlate their palpation with the underlying anatomy.
First, take the linear probe and then select the vascular preset on the tablet. Then, apply the gel to the probe and slide it in a transverse manner on the patient's midfoot. As the image appears on the screen, begin to optimize the settings using the depth and gain options.
Next, identify structures such as tendons, bony protrusions, or other vessels surrounding the dorsalis pedis artery, which can act as landmarks for the physical exam. These landmarks are reviewed in the JoVE video on the peripheral vascular exam.
When pressure is applied by the ultrasound probe, the artery should be less compressible than the accompanying vein and should have pulsatile flow. Mark the vessel using a skin marking pen, and then identify surface landmarks by inspection and palpation, using the finger pads to palpate the artery.
This process can be used to guide the palpation of all arteries relevant to the physical exam, including the brachial, radial, ulnar, femoral, popliteal, posterior tibialis, dorsalis pedis, carotid, and abdominal aorta.
The examination of the internal jugular or IJ vein has been discussed in the JoVE video "Cardiac Exam I: Inspection and Palpation".
To begin the ultrasound examination of this region, first take the linear probe and apply gel to it. Then select the vascular preset present on the ultrasound screen. Now, place the patient in a supine position with the head of the bed raised to 30 degrees, and then turn the patient's head slightly to the left.
With the indicator directed towards the patient's right, place the probe on the right side of the patient's neck in the transverse position. Two distinct anechoic structures should appear on the ultrasound screen. Optimize the image using the depth and gain buttons. The oval to the left of the screen is the IJ, and the circle towards the right of the screen is the carotid. The sternocleidomastoid muscle is located above the IJ vein.
With the IJ vein and carotid artery in view, note the difference in their pulsatility. The carotid artery has a single pulse, while the IJ vein has a triple pulse corresponding to the a, c, and v waves. The point at which the internal jugular vein tapers to smaller than the carotid is the point at which to measure the jugular venous pressure in short axis.
Now taking care not to apply excessive pressure with the probe, ask the patient to perform the Valsalva maneuver by inhaling deeply, holding their breath, and bearing down as if moving their bowels. As the patient performs this maneuver, notice the concomitant increase in the caliber of the IJ.
Next, ask the patient to inhale, and notice the corresponding collapse of the IJ. Correlate this with the increased blood return to the right side of the heart with inhalation, which leads to the physiologic splitting of the second heart sound. Then, obtain the long axis view of the IJ by rotating the probe 90 degrees, with the probe indicator directed towards the patient's head.
Now, slide the probe upwards on the patient's neck and identify the point where the IJ tapers, and then mark this point on the patient's neck with the skin marking pen. Take care not to apply excessive pressure while performing the exam. Measure the height of the mark above the sternal angle, which correlates with the height of the jugular venous pressure, or JVP, on the physical exam. Finally, inspect the patient and identify the IJ and height of the JVP, comparing this visual inspection with the JVP obtained using ultrasound.
The palpation of the abdominal aorta has been discussed in the previous JoVE video "Peripheral Vascular Exam".
First, ask the patient to lie in the supine position. Now palpate the patient's abdominal aorta and then mark its lateral walls with a skin marking pen. After that, measure the width of the abdominal aorta. Next, take the curvilinear probe and apply the gel to it. After that, select the abdominal preset available on the ultrasound screen.
With the probe indicator directed towards the patient's right, place the probe on the same area where the aorta was palpated. The ultrasound image with the abdominal aorta and associated landmarks such as spine and inferior vena cava should appear on the screen. Optimize the image using the depth and gain functions. Now, capture the image and measure the width of the aorta between the outer walls.
To conclude the exam, palpate the patient's abdominal aorta, measure the diameter, and compare the width of the abdominal aorta obtained by palpation and ultrasound.
