In which position should the patient be placed in order to palpate the popliteal pulse

Accessible arterial pulse sites

Carotid artery pulse - The common carotid artery is palpated on the neck below the jaw and lateral to the larynx/trachea (i.e., mid-point between your earlobe and chin) using the middle and index fingers.
Brachial artery pulse - The brachial artery is palpated on the anterior aspect of the elbow by gently pressing the artery against the underlying bone with the middle and index fingers. The brachial artery pulse is commonly used to measure blood pressure with a stethoscope and sphygmomanometer.
Radial artery pulse -The radial pulse is palpated immediately above the wrist joint near the base of the thumb (i.e., common site), or in the anatomical snuff box (i.e., alternative site), by gentlypressing the radial artery against the underlying bone with the middle and index fingers.
Femoral pulse - Thefemoral pulse is palpated over the ventral thigh between the pubic symphysis and anterior superior iliac spine with the middle and index fingers.
Popliteal pulse - Thepopliteal pulse is palpated on the posterior knee with the middle and index fingers; this pulse is more difficult to palpate as compared to other pulse sites.
Posterior tibial pulse - The posterior tibial pulse is palpated posterior and inferior to the medial malleolus by gentlypressing the tibial artery against the underlying bone with the middle and index fingers.
Dorsalis pedis pulse - Thedorsalis pedis pulse is palpated in the groove between the first and second toes slightly medial on the dorsum of the foot (i.e., dorsal-lateral to the extensor hallucis longus tendon and distal to the dorsal prominence of the navicular bone) with the middle and/or index fingers.
Temporal pulse - The temporal pulse (i.e., superficial temporal artery) is palpated on the temple directly in front of the ear with the index finger.
Apical pulse -The unilateral apical pulse (i.e., apex of the heart) can be located in the fifth intercostal space immediately to the left of the sternum using a stethoscope.  In contrast to other pulses, the apical pulse is measured over the heart and not an artery and is commonly heard with a stethoscope as opposed to palpated.

Definition/Introduction

A peripheral pulse refers to the palpation of the high-pressure wave of blood moving away from the heart through vessels in the extremities following systolic ejection.  This phenomenon is readily palpated and serves as a useful clinical tool, comprising one of the most commonly performed physical examination maneuvers at every level of medical care.  Palpation occurs at various locations of the upper and lower extremities including the radial, brachial, femoral, popliteal, posterior tibial, and dorsalis pedis arteries and most commonly evaluates the rate, rhythm, intensity, and symmetry.  Peripheral pulses can be used to identify many different types of pathology and are therefore, a valuable clinical tool.  Finally, modern medical technology allows for evaluation of pulses in ways beyond palpation, such as using Doppler ultrasound to characterize the pulse waveform further. 

Physiology

During systolic contraction of the heart, a high amplitude wave of blood gets ejected through the aortic valve out towards the periphery.  This high-pressure wave distends the arteries, especially compliant “elastic” or “conducting” arteries, which tend to be larger and closer to the heart.  The subsequent release of that distention somewhat sustains the systolic wave of blood throughout the body, creating a spike followed by a downward sloping plateau in pulse waveform. 

This waveform is propagated throughout the arterial system and can be felt and seen easily in several areas of the periphery.  Higher pressures lead to greater palpated intensity as the peripheral vasculature distends more forecfully and to a higher degree.  This phenomenon guides many of the clinical uses of the attribute of “intensity” when evaluating pulses. 

A normal heart rate (HR) is determined by age (younger patients have higher HR), setting (exertion generally increased HR), and status of respiration (HR increases with inspiration).  The intensity of the pulse is determined by blood pressure as well as other physiological factors such as ambient temperature. For example, colder temperatures cause vasoconstriction leading to decreased intensity.[1]  Besides the normal variation in a rhythm that occurs with the respiratory cycle, the heart rate should be regular in the absence of pathology. 

Pathological conditions can alter the rate, rhythm, intensity, and symmetry of the peripheral pulses, a fact that physicians can exploit when evaluating a patient. 

How to Perform

Pulses are accurately measured when the clinician places their fingertips onto the skin overlying the vessel (locations, see below) and focuses on different aspects of the pulse. (NB: although one often hears that utilization of the thumb for measuring pulses is less accurate secondary to increased perception of the clinician’s own pulsation during palpation, the author could not find data to support or refute this claim).[2] If possible, the limb under evaluation should have support throughout palpation.  

Evaluation begins with an initial gestalt about whether the pulse is bounding or weak, fast or slow, irregular or regular, and equal or unequal bilaterally. The intensity of the pulse is noted and subjectively graded on a scale of 0 to 4. By convention, “plus” always follows the number (e.g., 1+).  Zero refers to a nonpalpable pulse, 1+ is a barely detectable pulse, 2+ is slightly diminished but greater than 1+, 3+ is a normal pulse and should be easily palpable, and 4+ is “bounding” (e.g., stronger than normal).[1] After noting intensity, the clinician will turn their attention towards the rhythm, feeling long enough to be certain that the only variation in rhythm may be the minor fluctuation that occurs with the respiratory cycle.  Finally, the rate can be measured: the clinician observes a timepiece while counting the total number of palpable beats that occur during a predetermined amount of time.  Generally, 15 seconds is the minimum amount of acceptable time (multiplied by four to get the number of beats per minute) with more extended periods probably producing greater accuracy.  If relevant, the clinician can auscultate the heart while palpating a peripheral pulse to ascertain if every pulse gets transmitted as a palpable beat. 

 The choice of where to palpate a peripheral pulse is dependent on factors including the patient’s age, body habitus, and the clinical situation (e.g., resuscitation, routine vitals at an office visit, evaluation for peripheral arterial disease, etc.).  It is often relevant to compare bilateral pulses for symmetry as well as the difference between upper and lower extremity pulses. 

What follows will be a specific description of various peripheral pulses and where to find them.  Diagrams can be helpful to assist in learning where to find the pulses through palpation any many can be found online, including in the citations for this article [1].  It is also essential to recognize the presence of anatomic variation from patient to patient and in some cases, even a physiologic absence of a particular pulse in the expected region.  Finally, this description omits the carotid pulse in this description; although it is a significant pulse point, it is beyond the scope of an article focusing exclusively on peripheral pulses.  

In the upper extremities, the two peripheral pulses are the radial and brachial.  Examiners frequently evaluate the radial artery during a routine examination of adults, due to the unobtrusive position required to palpate it and its easy accessibility in various types of clothing.  Like other distal peripheral pulses (such as those in the feet) it also may be quicker to show signs of pathology.  Palpation is at the anterior wrist just proximal to the base of the thumb.  The brachial artery is often the site of evaluation during cardiopulmonary resuscitation of infants. It is palpated proximal to the elbow between the medial epicondyle of the humerus and the distal biceps tendon.  The carotid is the preferred pulse point used during resuscitation of adults. 

In the lower extremities, the commonly evaluated pulses are the femoral, posterior tibial, dorsalis pedis, and sometimes the popliteal.  The femoral pulse may be the most sensitive in assessing for septic shock and is routinely checked during resuscitation.[3]  It is palpated distally to the inguinal ligament at a point less than halfway from the pubis to the anterior superior iliac spine.  The posterior tibial pulse may be the most difficult to palpate, especially among less experienced clinicians.[4] It is located immediately posterior to the medial malleolus.[5]  The dorsalis pedis is at the anterior aspect of the foot, lateral to the extensor hallucis tendon, and is generally within 1cm of the bony prominence of the navicular bone.[6] Therefore, asking the patient to extend their first toe can help elevate this landmark and may make the pulse easier to identify, although it may be absent due to an anatomical variation in 10% of the general population.[1]  Finally, the popliteal pulse is present in the popliteal fossa slightly lateral of the midline. 

In addition to manual palpation, there are medical technologies that can detect pulse and study the waveform objectively.  Some of the more commonly used technologies with this capability include Doppler ultrasound and arteriography, while other technologies for monitoring peripheral vasculature are also emerging.[5] Arteriography and ultrasound are two methods that can provide a discrete waveform.  Doppler ultrasound is non-invasive, so it is often an option if the clinician cannot palpate a pulse manually.

Issues of Concern

Palpation of peripheral pulses in a patient with strong systolic blood pressure in a controlled setting by an experienced clinician is an important and reliable physical examination skill.  However, several studies show that when those ideal conditions degrade through the presence of pathology, time or environmental pressures, or inexperience of the clinician, the reliability of the clinical exam decreases.  In these cases, modern medical technology, as mentioned above, can assist in assessing peripheral pulses and determining the presence of pathology. 

Clinical Significance

The heart rate can be obtained through many devices routinely applied to the body in most medical encounters anywhere from the prehospital setting to the intensive care unit.  While obtaining a heart rate is valuable, there are many instances in which recording the peripheral pulse is desirable and increases the quality of patient care.  Peripheral pulses are clinically useful in identifying specific vascular pathologies, including peripheral arterial disease, vasculitis, congenital abnormalities, and others. 

Lower extremity peripheral pulses can be used to effectively screen for peripheral arterial disease (PAD).  Traditionally, the screening tool for PAD is the ankle-brachial index (ABI), which compares the systolic blood pressure in the ankle to that in the arm. This test is somewhat time-consuming and requires specific equipment and training.  However, a study has shown that when screening for PAD, if a patient has both pedal pulses intact bilaterally, the clinician could forgo ABI testing, as the likelihood of the patient having PAD, in that case, was under <3.5%.[7]  Other examples of intrinsic artery pathology affecting peripheral pulses include thrombosis or vasculitis, such as Takayasu arteritis.[1]

One important clinical use of peripheral pulses occurs during cardiopulmonary resuscitation (CPR) when the pulse is used to estimate the patient’s systolic blood pressure quickly.  Palpable pulses in various locations probably have a relationship to systolic BP, and the belief is that they are only palpable above certain systolic BP thresholds, with bigger and more central vessels having lower thresholds.  One previous estimation was that the radial pulse is no longer palpable below 80 systolic BP, the femoral unpalpable below 70, and the carotid unpalpable below 60.[1]  Although there have been doubts regarding these specific thresholds recently, there likely is a relationship as described above.[6] 

A general concept to bear in mind is that anything impinging the vessel can decrease peripheral pulses; this can be a result of chronic changes, such as tumors growing in proximity to the vessel, or can occur acutely in the setting of trauma.  Peripheral pulses distal to an injury are routinely checked after extremity trauma to ensure that the distal limb is still receiving adequate blood supply and to evaluate for anatomical disturbance of flow.  They require examination in cases of suspected compartment syndrome, with impingement occurring secondary to high pressures in the fascial compartment through which the vessel runs. It is crucial to note that pulselessness is an unreliable sign of compartment syndrome, although clinicians commonly use it for this purpose.[8]

The last two categories of pathology affecting peripheral pulses include vasospasm, as in Raynaud phenomenon, and congenital anatomic abnormalities.[1]  Peripheral pulses are part of a thorough physical examination used to asses for coarctation of the aorta. With 60 to 80% of infants going home undiagnosed with this condition after birth, there have been proposals for attention to this aspect of the physical exam in neonates as a possible means of improving patient care through increased detection of coarctation.[9]

Nursing, Allied Health, and Interprofessional Team Interventions

Peripheral pulse observation and recording is a useful assessment because of how quickly and easily it can be performed without specialized equipment or added cost.  It is commonly used to continue evaluating patients who may have had trauma, sepsis, or other forms of shock, as well as a screening tool for pathologies such as PAD.  Many types of clinical providers are trained to perform pulses, including nurses and physicians, and all those in the healthcare field who have taken a CPR course. Clear documentation is essential when talking about pulses in the electronic medical record, indicating the location of the pulse, on which side, the results, and if it has changed from previous assessments.  Sometimes peripheral pulses are marked with an "X" on the patient's skin so that there is continuity of care as different clinicians evaluate the patient over time. Therefore they know where the previous clinicians found the pulse and that it was present.

References

Hill RD, Smith RB. Examination of the Extremities: Pulses, Bruits, and Phlebitis. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Butterworths; Boston: 1990. [PubMed: 21250191]

Morris DC. The Carotid Pulse. In: Walker HK, Hall WD, Hurst JW, editors. Clinical Methods: The History, Physical, and Laboratory Examinations. 3rd ed. Butterworths; Boston: 1990. [PubMed: 21250154]

Deakin CD, Low JL. Accuracy of the advanced trauma life support guidelines for predicting systolic blood pressure using carotid, femoral, and radial pulses: observational study. BMJ. 2000 Sep 16;321(7262):673-4. [PMC free article: PMC27481] [PubMed: 10987771]

Brearley S, Shearman CP, Simms MH. Peripheral pulse palpation: an unreliable physical sign. Ann R Coll Surg Engl. 1992 May;74(3):169-71. [PMC free article: PMC2497570] [PubMed: 1616258]

Tibballs J, Weeranatna C. The influence of time on the accuracy of healthcare personnel to diagnose paediatric cardiac arrest by pulse palpation. Resuscitation. 2010 Jun;81(6):671-5. [PubMed: 20227813]

Hobson J, Bicknell C, Cheshire N. Dorsalis pedis arterial pulse: palpation using a bony landmark. Postgrad Med J. 2003 Jun;79(932):363. [PMC free article: PMC1742720] [PubMed: 12840142]

Londero LS, Lindholt JS, Thomsen MD, Hoegh A. Pulse palpation is an effective method for population-based screening to exclude peripheral arterial disease. J Vasc Surg. 2016 May;63(5):1305-10. [PubMed: 26947795]

McLaughlin N, Heard H, Kelham S. Acute and chronic compartment syndromes: know when to act fast. JAAPA. 2014 Jun;27(6):23-6. [PubMed: 24819953]

Cangussú LR, Lopes MR, Barbosa RHA. The importance of the early diagnosis of aorta coarctation. Rev Assoc Med Bras (1992). 2019 Feb;65(2):240-245. [PubMed: 30892450]

In which position should the patient be placed in order to palpate the popliteal pulse A have the patient lie prone with the knee flexed?

Which site is appropriate for palpation of the popliteal pulse?

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