The assessment of pulses
A pulse is the alternating expansion and recoil of arteries during each cardiac cycle; it is felt as the pressure wave passes through the arterial tree.1 A pulse can be palpated in any artery that lies close to the surface of the body by compressing the artery against firm tissue such as bone; this provides a simple method of counting heart rate. Due to accessibility the radial pulse is the most routinely used, the radial artery surfaces prominently at the wrist. However there are a variety of sites that can be utilised and may be clinically important; these include:
- The carotid artery
- The subclavian artery
- The brachial artery
- The aorta
- The ulna artery
- The femoral artery
- The popliteal artery
- The dorsalis pedis artery.
The locations of and flow of these can be found in the majority of anatomy and physiology textbooks or on-line.
Indications for measuring a pulse
A pulse is taken for a variety of reasons, both clinically and psychologically, these include:
- To gather information on the patients cardiovascular status
- To gain a baseline measurement for future review and monitoring
- To provide reassurance and gain a bond with patients who may be anxious.
The pulse is palpated to assess for the following:
- Rate
- Rhythm
- Amplitude.
Pulse rate
Normal pulse rates vary across client groups with factors such as age (see Table 5.1) and health status affecting rate. The pulse may also vary due to posture, for example a healthy adult male may have a pulse of 66 beats per minute when laying down, however this may rise to 70 when sitting up and rise again to 80 upon standing. This may rise further during times of distress or vigorous exercise; rates of between 140–180 are not unusual at these times.1
A normal adult resting pulse rate is between 60–100 bpm,2 with rates below 60 bpm termed as bradycardic and greater than 100 bpm tachycardic. These definitions are however arbitrary and should be taken in context of the clinical situation. There are numerous causes of both fast and slow pulse rates, examples of these can be seen in Table 5.2.
The pulse rate is a major factor in cardiac output, cardiac output is the volume of blood ejected by each ventricle per minute. This is a factor of stroke volume which is the volume pumped by each contraction of the ventricle and the heart rate. The relationship between these is shown in the following equation:
Cardiac output = heart rate × stroke volume
The pulse rate of a healthy individual tends to be relatively constant, however in disease states or injury the stroke volume can be reduced, this is especially prominent in damage to cardiac muscle and reduced blood volume states.2 In these cases cardiac output can only be maintained by increases in heart rate.
Table 5.1 Normal pulse rates per minute across the age continuum
Table 5.2 Causes of bradycardia and tachycardia, adapted from Douglas G, Nicol F, Robertson C. (2005) Macleod’s Clinical Examination. London: Elsevier.2
| Fast heart rate (tachycardia) | Slow heart rate (bradycardia) |
| Exercise | Sleep |
| Pain | Athletic training |
| Excitement/anxiety | Hypothyroidism |
| Fever | Medication (beta blockers, digoxin) |
| Medication (sympathomimetics, vasodilators) | Complete and second degree heart block |
| Hyperthyroidism | Sick sinus syndrome |
| Cardiac arrhythmia (atrial fibrillation, atrial flutter, supraventricular tachycardia, ventricular tachycardia) | Carotid sinus sensitivity |
Pulse rhythm
The rhythm of a pulse is regular in health, due to the co-ordination of the cardiac muscle fibres. The heart has an independent, co-ordinated conduction system that is a function of gap junctions and the hearts intrinsic cardiac conduction system.1,3 Gap junctions in cardiac muscle cells form interconnections between adjacent cells allowing for the passing of charged ions and therefore nervous impulses from cell to cell. The intrinsic cardiac conduction system consists of a group of non-contractile cardiac cells specialised in initiating and distributing impulses throughout the heart, so that it depolarises and contracts in an orderly manner.1
It is important to identify any irregularity of the pulse rhythm, considering whether this is a permanent change or an intermittent problem. A normal pulse may be altered by extra systoles, ectopic beats or cardiac arrhythmia. Common causes of an irregular pulse can be seen Box 5.1.
Often the pulse wave produced by an extra systole is difficult to palpate at the wrist as it is too weak, therefore this may produce a pulse deficit where the pulse felt at the wrist differs from the heart rate at the apex of the heart.2 Ventricular ectopic beats (extra beats originating from within the ventricles) are followed by a compensatory diastolic pause to allow for increased ventricular filling, thus a delayed beat is noted following the extra systole.
The presence arrhythmias such as atrial fibrillation or second degree heart block cause an irregularity in pulse rhythm due to loss of co-ordination of the electrical conduction system this may be through rapid electrical discharge or delayed discharge. Pulse rhythms can be classed either regular or irregular, however variations exist as seen in Table 5.3.
Table 5.3 Heart rate rhythm abnormalities4
| Regular | Self explanatory. It should be noted that heart rate can accelerate with inspiration and decrease with expiration in the normal adult. This is due to reduced tone of the vagus nerve (which slows the heart) during inspiration6. This is often referred to as sinus arrhythmia. |
| Irregularly irregular | This is a completely random pattern of pulsation. This is normally associated with atrial fibrillation where irregular impulses reach the ventricles causing irregular pulsation with no discernable pattern. |
| Regularly irregular | It is possible to have an irregular beat that occurs in a regular pattern. This is commonly seen in second degree heart blocks and pulsus bigeminus. |
| Regular with ectopics | A normal heart rate may be interrupted by a beat that is out of sequence making the pulse feel irregularly irregular. This requires electrocardiography to confirm. |
Pulse volume/character
Also referred to as amplitude, the strength of a pulse is a reflection of force of ejection of blood from the ventricles and the elasticity of the arterial wall. The flexibility of an elastic artery in a healthy young adult feels different from a hardened arteriosclerotic vessel. A large volume pulse may be felt during times of high cardiac output such as exercise, stress, heat and pregnancy. It may also occur with fever, thyrotoxicosis, anaemia, peripheral arteriovenous shunts and Paget’s disease.2 It may also be caused by aortic regurgitation, a condition which results in back flow of blood through the aortic valve. A low volume pulse is a sign of reduced stroke volume secondary to cardiovascular disease or peripheral vascular disease. A weak or thready pulse is most commonly seen in the hypovolaemic patient.3,5
The term character has a similar yet distinct meaning, with volume you are looking for the strength of a pulse, however with character the strength is assessed alongside how quickly or slowly this is achieved.6 This is best assessed at the carotid artery as the source is nearer to the heart and less subject to damping and distortion from the arterial tree. This is not an easy skill to acquire and requires experience therefore further reading is suggested (see References).
Pulse symmetry
Symmetry of the major arteries can provide useful information, however this is not routinely required. The undertaking of these tests is usually as a result of clinical suspicion of conditions such as acute aortic dissection or obstruction of the arterial tree.7 Pulses should be bilaterally equal and felt simultaneously, any delay or reduction of volume could indicate an abnormal pathology. Any delay between the radial artery and femoral artery on the same side may also indicate an underlying condition.
Technique for pulse taking
The technique for pulse taking applies to all pulses with only the location altering. A step by step guide to the process of pulse taking can be seen below.
The procedure for pulse taking
| Procedure | Rationale |
| 1. Explain and discuss the procedure to the patient | This is vital for both consent and relaxing the patient to get a more accurate reading. |
| 2. Place the first, second and third finger along the artery and press gently. | The thumb should not be used as it has a strong pulse which may be mistaken for the patient’s pulse (although in stronger pulses such as the brachial or the carotid it may be used as there is less likelihood of confusion). Pressing hard will occlude the artery making it difficult to palpate the pressure wave in the artery. |
| 3. The pulse should be counted for 15 seconds (minimum) and multiplied by 4 to provide the number of beats per minute.7 If the beat is irregular or is either too rapid or too slow then a 60 second count may be more appropriate.8,9 Make note of the strength and character of the pulse. | An irregular, slow or fast pulse may be poorly estimated using a short counting period, therefore a longer period will allow for a more accurate estimation of pulse rate. |
| 4. Counting should start from 1 as opposed to 0. | This method has been proven more accurate in recording heart rate.8 |
| 5. Record the pulse rate on the patient record. | This allows for trends to be recognised over time. |
| 6. Now palpate the opposite artery in the same manner. This should not be undertaken with the carotid artery. | If either pulse feels diminished in volume confirm the difference by simultaneously palpating the arteries. This may indicate conditions such as coarctation, blockage of any artery or aneurysm. You should not palpate both carotid arteries simultaneously as this will reduce cerebral blood flow. |
| 7. In carotid artery palpation the patient should lie on a bed or couch. | Palpation of the artery may cause a reflex bradycardia; this may cause a reduction in blood pressure and subsequent syncope. |
Locating the artery
There are four key arteries for pulse taking; the radial artery; the brachial artery; the femoral artery and the carotid artery. However, any artery may be of clinical significance, for example dorsalis pedis artery in the foot in extremity trauma, which is often used in assessing peripheral blood flow beyond the site of a leg injury.
The radial artery
The radial artery is most commonly palpated proximal to the wrist on the radial (thumb) side of the palmar aspect (inner) of the forearm. In some patients you may be able to see the pulsation of the artery; therefore it is often worth visually inspecting the area prior to locating the pulse.
The brachial artery
The brachial pulse is located medially to the bicep tendon in the crease of the elbow. In the anatomical position this will be on the medial aspect of the arm.
The femoral artery
This is palpated at the midway point between the upper extremity of the pubis and the anterior portion of the iliac spine.
The carotid artery
The carotid artery is located between the larynx and the anterior border of the sternocleidomastoid muscle. Gently pressing between these structures should allow for palpation of the artery.
The dorsalis pedis artery
This is often referred to as the pedal pulse and is located over the dorsum of the foot. This is felt by compressing over the tarsal bones of the mid-foot.
Capillary refill time measurement
Capillary refill time (CRT) is defined as the time taken for blood that has been removed from the tissues by the application of pressure to return to the tissues.10 Traditionally CRT has been taught as a tool for rapid cardiovascular assessment and an indication of the adequacy of tissue perfusion (often after traumatic injury). Normal CRT is proposed to be less than two seconds, with any time longer than this deemed as prolonged or abnormal, however there is considerable debate as to the accuracy of such a parameter.11
What can influence CRT?
In three studies that sought to verify the accuracy of a parameter for ‘normal’ CRT, results of up to 6 seconds were found.12 Findings suggest that CRT is age, sex and environment dependant, with adult males and children having significantly shorter CRT than women and the elderly. It has also been noted that ambient and body temperature can significantly alter CRT with reduced temperatures increasing CRT.12,13 There is also a potential influence upon CRT with the use of vasoactive medications such as inotropes in the critically ill.
Where do I measure?
Traditionally CRT is measured on the pulp of a digit,11 however the sternum and forehead are also areas of common usage. In the assessment of tissue perfusion below the site of an injury then naturally the site must be distal to the injury for the assessment to be of use. There is little definitive evidence to suggest one area for measurement is superior to another; however the use of differing areas for measurement, such as the foot may be linked to an increase CRT in cooler ambient temperatures.13
Is this accurate?
In a series of studies into the predictive value of CRT as an indicator of severity of illness or hypovolaemic status there appears little confidence in CRT use, with little validity found. Holcomb et al.14 and Schriger and Baraff15 found that CRT had little specificity and sensitivity in recognising hypovolaemia in trauma field studies and lab based studies respectively. A further study by Klupp and Keenan,16 suggests that CRT is a poor predictor of peripheral vascular supply and therefore limited in its application.
Whilst there is little evidence to support the use of CRT as a measure of haemodynamic status, it is perceived as a quick and easy test that can be undertaken in any condition17 and is therefore likely to remain as a part of clinical practice in the near future. It must however be considered as a part of a holistic assessment process and not in isolation.
Technique for measuring capillary refill time
There is no evidence to support a specific process for the measurement of CRT, therefore guidance is based upon current opinion and practice.
Capillary refill time measurement procedure
| Procedure | Rationale |
| 1. Explain the procedure to the patient and gain informed consent. | This is vital in all episodes of patient care to ensure conformity to professional duty of care and legal implications of consent. |
| 2. If using the pulp of the finger raise the hand to the level of the heart. | This will ensure assessment of arteriolar capillary and venous stasis refill.11 |
| 3. Apply pressure to the digit for five seconds to compress blood from the tissues. The pressure should be enough to produce blanching. | There is little evidence to support a specific time for this, however shorter times may not remove blood from the tissues and subsequently falsely reduce CRT. A single study in neonatal patients suggests that there is no significant difference between 3s–7s.18 However in the absence of strong evidence a suggested time of at least 5 seconds is recommended. |
| 4. Release the pressure and time how long it takes for the colour of the digit to return to the same colour as the surrounding tissues. | This is the capillary refill time. |
| 5. Document the findings. | This is essential to monitor trends over time. |
| 6. Remember to consider ambient temperature, patient temperature and other findings. | This will allow for more appropriate application of the findings. |
Blood pressure measurement
Blood pressure is defined as the force per unit area exerted on a vessel wall by the contained blood.1 Within the context of prehospital care blood pressure refers to systemic arterial blood pressure. The nearer a blood vessel is to the heart the higher the blood pressure. It is this pressure gradient that maintains blood movement throughout the body.1 Blood pressure is highest during the systolic phase of the cardiac cycle following contraction of the ventricle and lowest during the diastolic phase when the ventricles relax and refill. Blood pressure is usually expressed in term of millimetres of mercury (mmHg); this is the force exerted by a column of mercury of a height stated in millimetres. It is recorded as a systolic value over a diastolic value, for example 135/76 mmHg. The gap between the systolic pressure and the diastolic pressure is known as the pulse pressure.1
Blood pressure is a function of two main factors: (i) how much the elastic arteries near to the heart can be stretched and (ii) the volume of blood forced into them at any one time.1
Indications for monitoring blood pressure
Blood pressure is monitored for a variety of reasons including:
What Influences blood pressure?
Influences upon blood pressure are wide and varied. Blood pressure can be affected by weight, age, diet, time of day, pain, pregnancy, anxiety and further wide ranging medical conditions.19,20 The circumstances of the measurement itself may also be a factor in blood pressure readings with rises in systolic blood pressure of over 20 mmHg being attributed to anxiety and a perceived ‘white coat effect’.21 White coat hypertension is a condition in which a normotensive subject becomes hypertensive during blood pressure measurement, but then becomes normotensive again outside of the medical environment.
Normal blood pressure
Normotension is a difficult notion as blood pressure can vary in individuals and can fluctuate due to a variety of factors. General consensus suggests that systolic readings of around 120 mmHg and diastolic readings around 80 mmHg are considered ‘normal’.22 However these may vary between 140/90 mmHg to 100/60 mmHg.3 Any blood pressure reading must be taken in context as a blood pressure of 100/60 mmHg in a patient who has a normal blood pressure of 180/110 mmHg may well be hypotensive.
Hypertension
Hypertension is an elevation of the blood pressure that may be acute or chronic. In an adult this is generally considered to be any values above 140/90 mmHg and defined as ‘the level of blood pressure at which there is evidence that blood pressure reduction does more good than harm’.23 With variations in blood pressure measurement and the fluctuating nature of blood pressure, diagnoses of high blood pressure are not made upon single measurement but upon a series of measures. Hypertension is a significant risk factor for cardiovascular diseases such as myocardial infarction and stroke, therefore early diagnosis and treatment are key.
Hypotension
Hypotension or low blood pressure is generally defined as a systolic reading below 100 mmHg.1 It may simply be a variation in blood pressure, however in the acutely ill patient it may be an indication of hypovolaemia, sepsis or cardiogenic shock.24 Orthostatic or postural hypotension is a fall in systolic blood pressure of at least 20 mmHg or 10 mmHg in diastolic blood pressure within three minutes of quiet standing.25 This may be asymptomatic or cause the patient to feel light-headed and in older patients this is linked with falls and poor mobility.26
Mean arterial pressure
Mean arterial blood pressure is the average pressure required to move blood through the circulatory system. The mean arterial pressure may be calculated mathematically or electronically. Mathematically it is calculated as below:
For example, a blood pressure of 120/90 mmHg gives a mean arterial pressure of 100 mmHg.
Measuring blood pressure
There are two overall methods for measuring blood pressure; direct and indirect. Direct methods are considered more accurate, however these involve the placement of a pressure transducer (sensor) into an artery to directly measure the blood intra-arterial pressure. This method is commonly used in critical care areas such as intensive care units where patients require continuous and accurate monitoring. However this is not practical outside of these areas. Indirect blood pressure monitoring uses external cuffs to assess blood pressure either through auscultation or changes in cuff pressure. Wherever the environment, blood pressure measurements should be undertaken by trained healthcare professionals using equipment that is accurate, validated and well maintained. Failure to achieve this may result in erroneous or inaccurate readings being obtained.
The auscultatory method of measurement using mercury sphygmomanometers (a sphygmomanometer is a blood pressure measuring device) has been the mainstay of blood pressure measurement since blood pressure has been measured. However with an anticipated withdrawal of mercury devices for health and safety reasons alternative devices are required.27
Mercury sphygmomanometers
The mercury sphygmomanometer has been the perceived gold standard equipment for blood pressure measuring for many years. The simplistic design of these devices makes them easy to use and maintain. However there is a risk of chemical spillage, therefore special precautions are required in areas where they are used.26 Despite the simplistic design this equipment requires maintenance with studies finding that many devices are often inaccurate or defective due to poor maintenance schedules.28,29 This system relies upon the pressure created by a column of mercury within the device to provide a measurement.
Aneroid sphygmomanometers
In these devices the pressure is registered by a series of metal bellows that expand as the cuff pressure increases and a series of levers that register pressure on a circular scale.26 This device is however susceptible to damage from rough handling and poor maintenance.30 The accuracy of these monitors does appear questionable with variations between manufacturer and mercury devices.31
Non-invasive automated sphygmomanometers
The use of automated devices has been common place for many years, with many ambulance services and acute care settings opting for the ease of use to reduce staff workload and to allow for measurement in a variety of settings. The majority of these devices are based upon a technique known as oscillometry. This relies upon oscillations of pressure being felt in the cuff being maximal at mean arterial pressure.32 The oscillations begin well above systolic blood pressure and continue below diastolic blood pressure. This requires the blood pressure to be estimated from an algorithm. This method has the benefit of not requiring the cuff to be placed on specific points over the brachial artery as there is no transducer as with the mercury and aneroid sphygmomanometer.
The sphygmomanometer
A sphygmomanometer consists of a compression bag or bladder within a non-elastic cuff and an inflation bulb, pump or other device that is linked to the bag by durable tubing. In addition there is a measurement scale for reading the value and a control valve to release the pressure within the cuff.
Measuring blood pressure (manual methods)
Location of the measurement
The standard location for blood pressure measurement is the upper arm, with a stethoscope positioned over the brachial artery at the crease of the elbow. There are other sites that can be used such as the wrist, finger and leg but these have yet to fully validated for accuracy.33,34
Posture of the subject
Posture effects blood pressure, generally blood pressure will generally increase from the lying to the sitting or standing position. In the clinical setting the position of the patient should be based upon how they are most comfortable, however the position should be considered when documenting findings and making clinical decisions.
Arm position
The position of the arm can have a major influence upon blood pressure measurement. The upper arm should be at the level of the right atrium (mid-sternal level). If the arm is too high readings can be falsely low or if the arm is too low readings can be too high. It is suggested that the change in reading may be up to 10 mmHg or 2 mmHg for every inch above or below the heart level.35 If the arm in which measurement is being taken is unsupported this results in isometric exercise which can increase blood pressure and heart rate. Effects of this are estimated to be as much as a 10% increase in diastolic blood pressure, therefore supporting the arm is recommended.36
Which arm?
This remains a controversial area as some studies have found differences in blood pressure between arms in same subject simultaneous measurements.37 At present there appears no agreed reason for this, although a consensus of opinion suggests any marked difference (<20 mmHg systolic or>10 mmHg diastolic pressure) between arms should be investigated further as they may indicate pathology of the aorta or upper extremity arterial obstruction.26 It is recommended that blood pressure should initially be checked in both arms and the arm with the higher blood pressure should be used for subsequent measurements.26,38,39
The cuff and bladder
The sizing of the cuff and bladder in blood pressure measuring is paramount to accurate findings. The estimation of intra-arterial pressure by indirect means such as sphygmomanometry is predicated on a proper relationship between cuff size and the extremity. However sophisticated the measuring device used if it is dependent upon cuff occlusion of the arm, it will be prone to inaccuracy due to miscuffing. Several dated studies noted that undersized cuffs cause falsely high reading and oversized cuffs produced falsely low readings.40,41 With more recent studies suggesting that a cuff that is too small produces larger errors in blood pressure recording than a cuff that is too large.42–45 The optimal size of cuff that should be used should have a bladder length that is 80% of the arm circumference and a width that is at least 40% of arm circumference.26,46
The stethoscope (auscultation)
Using a stethoscope placed over the brachial artery it is possible to identify a series of five stages as the blood pressure reading falls from the systolic to the diastolic.1,26 These sounds are known as Korotkoff’s sounds. During the raising of the pressure in the cuff and bladder the blood flow through the brachial artery is cut occluded, as it is gradually deflated pulsatile blood flow is restored though the artery, resulting in a series of sounds. These sounds have been classified as phases as seen below:
Phase 1: A clear tapping sound corresponding with the return of a palpable pulse. The onset of phase 1 corresponds with systolic blood pressure.
Phase 2: Sounds become softer and longer.
Phase 3: Sounds become crisper and louder.
Phase 4: Sounds become softer and muffled.
Phase 5: Sounds disappear completely. This is considered to be the diastolic blood pressure value.
The Korotkoff sounds method tends to give lower systolic values than that of intra-arterial methods and diastolic values that are higher.47–50 There has been disagreement over the reliability of using phase 4 or 5 to determine diastolic value as it is often difficulty in differentiating when phase 4 commences, in addition this tends to give an inaccurately high diastolic value. It is now considered appropriate to use phase 5 sounds for diagnostic accuracy as they are easier to determine. This method is not however possible in all patients, as in some patients, the disappearance of sounds does not occur despite complete deflation of the cuff. In this scenario the 4th phase sound should be used.37,51 Patients who are prone to the continuation of the Korotkoff sounds include pregnant women, those with aortic insufficiency and patients with arterio-venous fistulas (for haemodialysis).
In older patients with a wide pulse pressure the Korotkoff sounds may disappear between the systolic and diastolic pressures and reappear as the cuff is deflated, this is known as the auscultatory gap.26 The auscultatory gap is thought to be a result of fluctuating intra-arterial pressures or organ damage.52
Palpatory estimation of blood pressure
In some situations such as a noisy road traffic collision site it can be difficult to achieve a valid blood pressure based upon auscultatory techniques. This is also the case with those patients in whom it is difficult to determine the Korotkoff sounds. In these situations it is possible to estimate systolic blood pressure by palpation of the brachial artery when deflating the cuff.53 The cuff should firstly be inflated to approximately 30 mmHg above where the brachial pulse can no longer be felt and then as the cuff is deflated the return of the pulse should be noted. This is suggested to be the approximate value of the systolic blood pressure.
Advanced Trauma Life Support principles54 suggest that if the patient has a carotid pulse that the systolic blood pressure is 60–70 mmHg; if carotid and femoral pulses are present the systolic blood pressure is 70–80 mmHg and if the radial pulse is present the systolic blood pressure is greater than 80 mmHg. However there is little support provided for these broad estimations, Deakin and Low (2000)55 found these figures to be an overestimate of actual intra-arterial blood pressure in a small scale study. It appears that the suggested ATLS estimations may not be reliable and management should not be based solely upon information gained by this technique until further evidence has been provided to either support or dispel the proposal.
