INTRODUCTION — Correct measurement and interpretation of the blood pressure (BP) is essential in the diagnosis and management of hypertension. It is important that BP machines are properly calibrated, appropriate cuff sizes are selected, and, when BP is measured in an office-based setting, personnel are properly trained and the patient is positioned correctly.
BP measurement in the diagnosis and management of hypertension, including the technique required for office-based measurements, will be reviewed here. Detailed descriptions of ambulatory and home-based BP monitoring are presented elsewhere. (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
An overview of hypertension in adults and discussions pertaining to patient selection for antihypertensive therapy, choice of antihypertensive therapy, and management of older adults with isolated systolic hypertension can be found in other topics:
OUR APPROACH TO MEASURING BLOOD PRESSURE
Selecting a measurement strategy — Blood pressure (BP) can be measured using one of the following three acceptable strategies:
●Ambulatory BP monitoring (ABPM)
●Home BP monitoring
●Office-based BP measurements, which should, ideally, be automated
The specific aspects of these three methods of BP measurement are discussed below. (See 'Ambulatory blood pressure monitoring' below and 'Home blood pressure monitoring' below and 'Office-based blood pressure measurement' below.)
Screening for hypertension is typically performed in the clinician's office. Although these office measurements are recommended to identify patients who might have hypertension, many such individuals will not have hypertension upon further testing (ie, they have white coat hypertension) [1,2].
Our approach to measuring BP for the purposes of diagnosing and confirming hypertension depends in part upon the feasibility of performing ABPM, home BP monitoring, and, if neither ABPM nor home BP monitoring are feasible, whether or not an automated office BP (AOBP) device is used in the clinician's office [1-6]:
●We perform ABPM if it is feasible to establish a diagnosis of hypertension. (See 'Ambulatory blood pressure monitoring' below.)
●Sometimes, ABPM is not feasible (ie, due to lack of access, expense, or lack of insurance coverage); in such cases, we perform home BP monitoring if it is feasible. (See 'Home blood pressure monitoring' below.)
●If home BP monitoring is not feasible (patient cannot afford a cuff or find a suitably sized cuff), then BP must be measured in the office. However, if office BP is used to confirm the diagnosis of hypertension, multiple measurements on different days are required (see 'Office-based blood pressure measurement' below):
•If the office has an AOBP device that can automatically take and average multiple measurements with the patient, preferably, alone in a room, then we use this technique to measure BP. (See 'Automated office blood pressure measurement' below.)
•Conversely, if no such AOBP device is available, we use routine office BP measurements. (See 'Routine office-based blood pressure' below.)
Patients being managed for previously diagnosed hypertension should monitor their BP at home, if possible. If home BP cannot be monitored, management of the patient can be informed by office measurements (performed using an AOBP device if available).
Practical aspects of ABPM, home BP measurement, AOBP, and routine office BP are presented below. (See 'Ambulatory blood pressure monitoring' below and 'Home blood pressure monitoring' below and 'Office-based blood pressure measurement' below.)
Interpretation of blood pressure measurements — In general, measurements obtained by ABPM and home BP monitoring are lower than those obtained by routine office measurement by approximately 5 to 10 mmHg (table 1) [7-9]. In addition, office readings obtained using an AOBP device (in which multiple BP measurements are automatically obtained and averaged with the patient, preferably, alone in a room [ie, unattended measurement]) more closely approximate ABPM and home BP readings than standard office measurement [7,8,10,11].
In one meta-analysis of 26 studies and over 7000 patients, BPs obtained by AOBP, daytime ABPM, home BP monitoring, and routine manual measurement were compared . AOBP values were 10/4 mmHg lower than routine office measurements obtained by clinicians and 7/4 mmHg lower than routine office measurements obtained by non-clinicians. In addition, there were no significant differences between measured AOBP and daytime ABPM values.
AOBP does not necessarily have to be performed while the patient is alone (ie, unattended). Several studies, including a retrospective survey of clinics participating in the Systolic Blood Pressure Intervention Trial (SPRINT) , suggest that attended and unattended AOBP provide similar results when performed in a standardized fashion with no talking between the participant and observer . However, other studies reported a difference between attended and unattended measurement [14-16]. Thus, unattended AOBP, if possible, is preferred in routine clinical practice in order to prevent the patient and clinician from conversing during the rest or measurement period and producing a white coat effect.
The definitions used to define hypertension are presented elsewhere. (See "Overview of hypertension in adults", section on 'Definitions'.)
PRACTICAL AND TECHNICAL ASPECTS OF MEASUREMENT STRATEGIES
Ambulatory blood pressure monitoring — Ambulatory blood pressure monitoring (ABPM) is determined using a device (worn by the patient) that takes blood pressure (BP) measurements over a 24- to 48-hour period, usually every 15 to 20 minutes during the daytime and every 30 to 60 minutes during sleep . Six to eight hours of ABPM may be adequate if full 24-hour readings cannot be obtained . These BPs are recorded on the device, and the average day (diurnal) and night (nocturnal) BPs are determined from the data by a computer. The percentage of BP readings exceeding the upper limit of normal can also be calculated. When ABPM is used, hypertension is defined as a 24-hour average BP greater than or equal to 125/75 mmHg, average daytime BP greater than or equal to 130/80 mmHg, or average nighttime BP greater than or equal to 110/65 mmHg . (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
ABPM has been considered to be the reference standard for the diagnosis of hypertension and is a better predictor of future cardiovascular events as compared with conventional office-based BP measurements. The 2015 statement from the US Preventive Services Task Force recommends obtaining measurements outside of the clinical setting for diagnostic confirmation of hypertension, and the 2017 ACC/AHA hypertension guidelines also recommend out-of-office BP measurements to confirm diagnosis of hypertension and for titration of antihypertensive medications. ABPM is recommended as the reference standard, and home BP monitoring is acceptable as an alternative to ABPM [19-21]. A patient with elevated office-based BP but normal daytime ambulatory BP is considered to have office hypertension or "white coat" hypertension. (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
Compared with ABPM, the sensitivity and specificity of office-based BP measurements are poor [2,22]. This was shown in a systematic review of 20 studies including 5863 patients that compared ABPM with office-based and home BP monitoring . When compared with a mean 24-hour BP of 135/85 mmHg or greater, the average sensitivity and specificity of an office-based BP of 140/90 mmHg or greater were both 75 percent. The positive predictive value for an elevated office-based measurement was poor. If, for example, the prevalence of hypertension in the population was 30 percent, the probability that a patient whose office-based BP was 140/90 mmHg or greater would have hypertension confirmed by ABPM was 56 percent. In addition to problems with accuracy, conventional office-based measurement of BP may be a less cost-effective way to diagnose hypertension than ABPM .
However, ABPM is not available in most clinicians' offices. This is due to a combination of factors, including lack of knowledge regarding its utility, its expense, and minimal reimbursement by third-party payers.
Home blood pressure monitoring — In view of the cost and limited availability of ambulatory monitoring, increasing attention is being given to home monitoring with inexpensive (USD $40 to $60) semi-automatic devices. If the BP is taken at home to establish the diagnosis of hypertension or to assess BP control, the optimal schedule is unclear. Increasing evidence suggests that at least 12 to 14 measurements should be obtained, with both morning and evening measurements taken, over a period of one week [17,24-27]. (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
Such self-recorded casual BP measurements taken at home or work correlate more closely with the results of 24-hour or daytime ambulatory monitoring than with office-based measurements [6,17,24,28]. (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
Home BP monitoring is also useful in the management of patients with an established diagnosis of hypertension. Various trials have shown that home monitoring can improve BP control and compliance. This issue is discussed elsewhere. (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
All home monitors should be checked for accuracy, initially and then at least annually, in the clinician's office, and patients or caregivers should be able to demonstrate the correct technique of BP measurement. When using home monitoring in patients with obesity, appropriately sized arm cuffs may be unavailable; in these situations, wrist cuffs may be used .
Cuff inflation hypertension — A marked rise in BP caused by cuff inflation during self-measurement (cuff inflation hypertension) may result in some patients from the physical exertion needed to inflate the cuff or from anticipatory anxiety.
Some BP monitors designed for home use, particularly ones that are less expensive, require the patient to manually inflate the cuff. If the cuff is manually inflated, the muscular activity used to inflate the cuff may acutely raise the BP by as much as 12/9 mmHg, an effect that dissipates within 5 to 20 seconds . Even when using automated (rather than manual) self-measurement devices, an average systolic pressure increase of 4 to 7 mmHg may occur in anticipation of cuff inflation (presumably due to an anxiety response) .
Thus, when using a manual device, inflating the cuff to at least 30 rather than 20 mmHg above systolic and then allowing the sphygmomanometer to fall no more than 2 to 3 mmHg per second is desirable, both for accurate measurement and to permit an exertional effect to disappear . Regardless of the device, taking multiple sequential measurements and discarding the first reading may remove an effect of anticipatory anxiety.
Office-based blood pressure measurement — Office-based BP measurement may likely continue to be the primary technique for both the diagnosis and management of hypertension in the United States and elsewhere due in part to the lack of payment for ABPM or home BP monitors by most third-party payers and the unavailability of ABPM or home BP monitors in some areas. In addition, randomized trials upon which hypertension treatment recommendations are based employed office-based BP measurements, not ABPM or home BP measurements.
The remainder of this section will review the recommendations that have been made to achieve maximum accuracy in office-based BP measurement (table 2) [4,19,32-34]. However, many clinicians do not follow one or more of these recommendations, leading to potential errors in diagnosis and management and to the conclusion that office readings are simply unreliable [32,35].
The proper measurement of office-based BP requires attention to all of the following:
●Time of measurement
●Type of measurement device
●Technique of measurement
●Number of measurements
Routine office-based blood pressure — Most clinicians' offices do not use an automated office BP (AOBP) device but rather measure BP manually (using the auscultatory method) or with an oscillometric device while a medical professional is present in the room with the patient.
Time of measurement — BP is variable throughout the course of the day, as shown clearly by ABPM (table 1). Daytime BP, which is when patients are evaluated in the office, can change from hour to hour and is affected by mental and physical activity, stress, and when antihypertensive medications were taken. (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
For office monitoring of antihypertensive therapy, the BP should optimally be measured at approximately the same time of day and before medications are taken to estimate the trough or nadir effect.
Extraneous variables that can influence the BP should be avoided in the 30 minutes prior to evaluation . These include food intake, strenuous exercise, smoking, and the ingestion of caffeine:
●Smoking transiently raises the BP; thus, the office BP may underestimate the usual BP in a heavy smoker who has not smoked for more than 30 minutes before the measurement is made. (See "Smoking and hypertension".)
●Caffeine intake can raise the BP acutely, primarily in non-habitual coffee drinkers. (See "Cardiovascular effects of caffeine and caffeinated beverages".)
●Taking the BP in a cool room (12°C or 54°F) or while the patient is talking can raise the measured value by as much as 8 to 15 mmHg.
Type of measurement devices — Mercury and aneroid sphygmomanometers, which employ the auscultatory method of measurement, are being used less frequently: the former because of mercury toxicity and the latter because of frequent inaccuracies. Oscillometric measuring devices (automated or non-automated) are increasingly being used in medical offices  and are also used for home monitoring .
Cuff size — Use of a properly sized cuff is essential . If too small a cuff is used, the pressure generated by inflating the cuff may not be fully transmitted to the brachial artery; in this setting, the pressure in the cuff may be considerably higher than the intraarterial pressure, which can lead to overestimation of the systolic pressure by as much as 10 to 50 mmHg in patients with obesity.
The length of the BP cuff bladder should be 80 percent, and the width at least 40 percent (and some use 46 percent), of the circumference of the upper arm [37,39].
We agree with the American Heart Association regarding the appropriate cuff size for a designated arm circumference :
●Arm circumference 22 to 26 cm, "small adult" cuff, 12 x 22 cm
●Arm circumference 27 to 34 cm, "adult" cuff, 16 x 30 cm
●Arm circumference 35 to 44 cm, "large adult" cuff, 16 x 36 cm
●Arm circumference 45 to 52 cm, "adult thigh" cuff, 16 x 42 cm
Pseudohypertension — Compression of the brachial artery may require a cuff pressure greater than systolic in patients with stiff vessels due to marked arterial calcification. This phenomenon, called pseudohypertension, is characterized by systolic and diastolic pressures estimated from the sphygmomanometer that are 10 mmHg or more above the directly measured intraarterial or oscillometric pressure . (See "Definition, risk factors, and evaluation of resistant hypertension", section on 'Cuff inflation hypertension'.)
Patient position — The BP should be taken with the patient in a seated position with the back supported and legs uncrossed . The diastolic pressure may be higher by 6 mmHg if the back is unsupported, and the systolic pressure may be raised by 5 to 8 mmHg if the legs are crossed .
For some patients, particularly older adults and diabetic patients, supine, sitting, and standing BPs are useful to detect orthostatic hypotension . (See "Mechanisms, causes, and evaluation of orthostatic hypotension".)
The arm should be supported at the level of the heart . If the arm is allowed to hang down unsupported, the measured BP will be elevated by 10 to 12 mmHg due to the added hydrostatic pressure induced by gravity . The patient should sit quietly for five minutes before the BP is measured . Bladder distension, talking, and background noise can all affect the measured BP .
Even under optimal conditions, many patients are apprehensive when seeing the clinician, resulting in an acute rise in BP. Twenty to 30 percent of patients with hypertension in the clinician's office are normotensive outside of the office . This phenomenon, called "white coat" or isolated office hypertension, should be suspected in any patient with markedly elevated office BP in the absence of end-organ damage or with normal ambulatory BPs taken at work or at home (table 3 and figure 1). The presence of white coat hypertension can be confirmed by 24-hour ABPM or self-recorded readings at home. This white coat effect can usually be minimized by having a nurse measure the BP (figure 2)  and by using automated BP devices which record multiple readings with the patient alone in the examination room. This white coat effect can persist for years (figure 3). (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
Cuff placement — The BP cuff should be placed with the bladder midline over the brachial artery pulsation . The lower end of the BP cuff should be 2 to 3 centimeters above the antecubital fossa to minimize artifactual noise related to the stethoscope touching the cuff.
Ideally, the cuff should be placed on the bare arm or over a thin sleeve. The patient's sleeve should not be rolled up, as this may act as a tourniquet, nor should the measurement be taken over a thick sleeve, as this may lead to an overestimate of the patient's BP .
Technique of measurement — Once the cuff is adequately placed, neither the patient nor the observer should talk during the measurement. The BP should be taken with the patient's arm supported at the level of the heart.
Auscultatory method of measurement — Auscultatory methods depend upon the skill and experience of the operator. The cuff should be inflated to a pressure approximately 30 mmHg greater than systolic, as estimated from the disappearance of the pulse in the brachial artery by palpation . Initial estimation of the systolic pressure by palpation avoids potential problems with an auscultatory gap, wherein the Korotkoff sounds transiently disappear as the cuff is deflated. As an example, the Korotkoff sounds in a patient with a systolic pressure of 180 mmHg may be first heard at 180 mmHg, disappear at 165 mmHg, and then be reheard at 140 mmHg. If the cuff is only inflated to a pressure of 160 mmHg, no sounds will be heard until 140 mmHg; as a result, the latter value will be mistakenly considered to be the systolic pressure.
With the auscultatory method, the stethoscope should be placed lightly over the brachial artery since the use of excessive pressure can increase turbulence and delay the disappearance of sound. The net effect is that the diastolic pressure reading may be artifactually reduced by up to 10 to 15 mmHg.
The cuff should be deflated slowly at a rate of 2 to 3 mmHg per second . The systolic pressure is the pressure at which the pulse is first heard by auscultation (Korotkoff phase I).
As the cuff is deflated below the systolic pressure, the pulse continues to be heard until there is abrupt muffling (phase IV) and, approximately 8 to 10 mmHg later, disappearance of sound (phase V). There is general consensus that phase V should be used to determine diastolic BP in adults .
Oscillometric method of measurement — Oscillometric devices have an electronic pressure sensor to record the pressure oscillations of the arteries and automatically inflate and deflate the cuff. Proprietary algorithms are used by these devices to calculate systolic and diastolic BPs.
The BP should be measured initially in both arms. If there is a large disparity due to a unilateral arterial lesion (usually a subclavian stenosis ), the arm with higher pressure should be used .
A disparity in BP between the arms predicts not only the presence of subclavian stenosis but also a higher risk of cardiovascular disease. In a meta-analysis that included 20 studies, patients who had a BP disparity of 10 mmHg or more between the arms were significantly more likely to have peripheral arterial disease (42 versus 12 percent) . A disparity of 15 mmHg or more was significantly associated with a higher prevalence of cerebrovascular disease (11 versus 4 percent) and a significantly greater relative risk (RR) of cardiovascular death (RR 1.63, 95% CI 1.10-2.41).
The BP should be taken at least twice during each office visit, with the measurements separated by one to two minutes to allow the release of trapped blood. If the second value is more than 5 mmHg different from the first, continued measurements should be made until a stable value is attained. The recorded value on the patient's chart should be the average of the last two measurements.
Need for multiple measurements — In the absence of end-organ damage, the diagnosis of hypertension should not be made until the BP has been measured on at least three visits, spaced over a period of one week or more .
Sequential studies have shown that the BP drops by an average of 10 to 15 mmHg between the first and third visits in newly diagnosed patients, with a stable value not being achieved in some patients until more than six visits . Thus, many patients considered to be hypertensive at the initial visit are in fact normal. (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
In addition, multiple measurements are necessary when monitoring patients who are already on treatment for hypertension. A study of 444 men with longstanding, poorly controlled hypertension found that a single clinic or home systolic BP of 120 to 157 mmHg had less than an 80 percent chance of correctly classifying the patient as being in or out of control . Correct classification was maximized at five to six measurements, with most of the benefit occurring with the second measurement.
If the BP is taken at home to establish the diagnosis of hypertension or to assess BP control, at least 12 to 14 measurements should be obtained, with both morning and evening measurements taken over one week. Home BP monitoring is discussed in detail elsewhere. (See "Out-of-office blood pressure measurement: Ambulatory and self-measured blood pressure monitoring".)
Alternative sites for measurement — BP can be measured in the leg or wrist.
Leg blood pressure — There are occasional patients in whom the BP needs to be measured in the legs. The classic example is with suspected coarctation of the aorta in which there is an arm-to-leg gradient, but it is more commonly required in patients who cannot have BP measured in the arms (eg, due to surgery, indwelling catheters, vascular fistulae, or grafts). (See "Clinical manifestations and diagnosis of coarctation of the aorta", section on 'Blood pressure and pulses'.)
The principles of BP measurement in the leg are similar to those described above in the arm, with use of an appropriately sized cuff. (See 'Cuff size' above.)
In normal subjects, the systolic pressure in the lower extremity is usually higher than that in the brachial artery . In a systematic review of 44 studies comparing arm and leg BP readings performed in the supine position, mean systolic BP was higher in both the calf (by 10 mmHg, 95% CI 4 to 16 mmHg) and the ankle (17 mmHg, 95% CI 15 to 21 mmHg) than in the arm . However, the high variability in arm-leg BP difference in these studies can make it difficult to reliably translate leg pressures into arm pressures. In addition, no oscillometric BP monitors have been validated for lower-extremity BP measurements.
In patients with vascular disease, systolic BP at the ankle is often lower than the BP in the arm [56,57]. (See "Noninvasive diagnosis of upper and lower extremity arterial disease", section on 'Lower extremity segmental pressures'.)
Wrist blood pressure — Measurement of BP at the radial artery (wrist) may sometimes be necessary in people with obesity (when a sufficiently large cuff cannot be obtained, such as when measurement devices are purchased for home monitoring) and in patients with breast cancer who have had axillary lymph node resection . However, given questions about accuracy, BP measurement at the wrist should not be used routinely if brachial BP measurement is feasible.
Technical considerations may make accurate measurement of BP at the wrist more challenging than measurements taken at the brachial artery . At the wrist, the hydrostatic pressure related to the lower position of the wrist relative to the heart can result in a further false elevation of BP. This can be minimized by taking the BP with the wrist kept at the level of the heart. In addition, an automatic device's sensor must remain directly over the radial artery for an accurate reading, and wrist flexion may interfere with appropriate sensor positioning.
Devices that measure pressure in the finger are not recommended, including for home monitoring .
Automated office blood pressure measurement — AOBP devices utilize oscillometric methodology and take multiple consecutive BP readings in the office with the patient sitting and resting, preferably alone (ie, unattended). Compared with conventional manual office measurements, unattended AOBP decreases the white coat response, avoids talking during the rest and measurement periods, and avoids observer error and bias [7,13,58]. Available AOBP devices differ in the number of readings taken and the number of minutes before the first BP measurement is recorded [34,59]. Evaluation of machine accuracy should be performed at periodic intervals. BP monitors that have been validated in accordance with the standards published by the Association for the Advancement of Medical Instrumentation, the ANSI/AAMI/ISO, or British Hypertension Society protocols should be used. Useful information about the various AOBP devices that are marketed can be found here and here.
Proper patient positioning, cuff size, and placement are still necessary; the same principles that apply to routine office BP also apply to AOBP. (See 'Patient position' above and 'Cuff size' above and 'Cuff placement' above.)
However, several aspects of performing AOBP differ from those of routine office BP:
●Patients do not necessarily need to rest for five minutes prior to having AOBP measured . Several studies have shown that systolic pressure may be as much as 7 mmHg lower with AOBP following an enforced rest period compared with daytime average ambulatory BP [60,61].
●AOBP does not need to be performed more than one time during an office visit. The fact that these devices can be programmed to automatically obtain and average three or more readings satisfies the criteria for multiple consecutive measurements. The authors of this topic feel that three readings are likely sufficient, no matter which AOBP device is used.
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Hypertension in adults".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Beyond the Basics topics (see "Patient education: High blood pressure in adults (Beyond the Basics)" and "Patient education: High blood pressure treatment in adults (Beyond the Basics)" and "Patient education: High blood pressure, diet, and weight (Beyond the Basics)")
SUMMARY AND RECOMMENDATIONS
●Acceptable techniques for BP measurement – Blood pressure (BP) can be measured using one of the following three acceptable strategies (see 'Our approach to measuring blood pressure' above):
•Ambulatory BP monitoring (ABPM)
•Home BP monitoring
•Office-based BP measurements, which may be automated (automated office blood pressure [AOBP]) or manual
●Diagnosing hypertension: Our approach – Screening for hypertension is typically performed in the clinician's office. Although these office measurements are recommended to identify patients who might have hypertension, many such individuals will not have hypertension upon further testing (ie, they have white coat hypertension) (table 3). Our approach to measuring BP for the purposes of diagnosing and confirming hypertension depends in part upon the feasibility of performing ABPM, home BP monitoring, and, if neither ABPM nor home BP monitoring are feasible, whether or not an AOBP device is used in the clinician's office (algorithm 1) (see 'Selecting a measurement strategy' above):
•We perform ABPM if it is feasible to establish a diagnosis of hypertension. (See 'Ambulatory blood pressure monitoring' above.)
•Sometimes, ABPM is not feasible (ie, due to lack of access, expense, or lack of insurance coverage); in such cases, we perform home BP monitoring if it is feasible. (See 'Home blood pressure monitoring' above.)
•If home BP monitoring is not feasible (patient cannot afford a cuff or find a suitably sized cuff), then BP must be measured in the office. However, if office BP is used to confirm the diagnosis of hypertension, multiple measurements on different days are required (table 2) (see 'Office-based blood pressure measurement' above):
-If the office has an AOBP device that can automatically take and average multiple measurements with the patient, preferably, alone in a room, then we use this technique to measure BP. (See 'Automated office blood pressure measurement' above.)
-Conversely, if no such AOBP device is available, we use routine office BP measurements. (See 'Routine office-based blood pressure' above.)
●Managing hypertension: Preferred measurement strategy – Patients being managed for previously diagnosed hypertension should monitor their BP at home, if possible. If home BP cannot be monitored, management of the patient can be informed by office measurements (performed using an AOBP device if available). (See 'Selecting a measurement strategy' above.)
All home monitors should be checked for accuracy, initially and then at least annually, in the clinician's office, and patients or caregivers should be able to demonstrate the correct technique of BP measurement. When using home monitoring in patients with obesity, appropriately sized arm cuffs may be unavailable; in these situations, wrist cuffs may be used. (See 'Home blood pressure monitoring' above.)
●BP readings vary according to measurement strategy – In general, measurements obtained by ABPM and home BP monitoring are lower than those obtained by routine office measurement by approximately 5 to 10 mmHg (table 1). In addition, office readings obtained using an AOBP device (in which multiple BP measurements are automatically obtained and averaged with the patient alone in a room [ie, unattended measurement]) more closely approximate ABPM and home BP readings than standard office measurement. The definition of hypertension is presented elsewhere. (See "Overview of hypertension in adults", section on 'Definitions'.)
●Careful technique required for accurate manual BP measurement – If manual office readings are used to diagnose and monitor BP, proper measurement requires attention to all of the following (table 2) (see 'Routine office-based blood pressure' above):
•Time of measurement (see 'Time of measurement' above)
•Type of measurement device (see 'Type of measurement devices' above)
•Cuff size (see 'Cuff size' above)
•Patient position (see 'Patient position' above)
•Cuff placement (see 'Cuff placement' above)
•Technique of measurement (see 'Technique of measurement' above)
•Number of measurements (see 'Need for multiple measurements' above)
ACKNOWLEDGMENT — The editorial staff at UpToDate acknowledge Norman Kaplan, MD, who contributed to an earlier version of this topic review.
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