Chronic hypertension blood pressure measurement
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor-In-Chief: Yazan Daaboul; Serge Korjian
Overview
The use of a sphygmomanometer in the clinic to measure blood pressure is the most accurate technique to diagnose hypertension. Blood pressure measurements must be performed appropriately according to a standardized technique that involves adequate device and cuff choice and comfortable positions. Sources of error, involving the sphygmomanometer, the patient, and the technique itself must also be considered and avoided. Other techniques for diagnosis, such as ambulatory and self blood pressure measurements may also be helpful, particularly for the follow-up of patients with hypertension.
Blood Pressure Measurement
Blood pressure measurement using the sphygmomanometer yields two values that assess the pressure exerted by the blood on the walls of the arteries at two points in time:
Systole
The maximum exerted pressure during a ventricular contraction and during expulsion of blood from the heart chambers into the aorta and corresponding arteries. The corresponding value measured by the sphygmomanometer is the systolic blood pressure.
Diastole
The minimum exerted pressure directly before the next heartbeat. The corresponding value measured by the sphygmomanometer is the diastolic blood pressure. Conventionally, blood pressure is frequently denoted as systolic and diastolic pressures and expressed in mmHg. Another way to denote blood pressure is using the mean blood pressure, calculated by:
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Mean Blood Pressure = [Systolic Blood Pressure + (2 x Diastolic Blood Pressure)] / 3 |
Nonetheless, blood pressure is a continuously fluctuating hemodynamic parameter with various factors leading to such fluctuations other than the cardiac cycle. Those include the respiration, the baroreceptor loop, hormones, in addition to others. Therefore, experts do not rely solely on static blood pressure parameters but also on dynamic ones, such as pulse pressure, defined as the pressure difference in systolic and diastolic blood pressure, in the evaluation of blood pressure curve.
Hence, accurate, precise, and reproducible measurements are pre-requisites for the evaluation of blood pressure. The level of blood pressure plays a major role in the diagnostic, therapeutic, and prognostic decision-making processes of various disease states.
Blood Pressure Measurement Technique
According to “Practice Guidelines of the European Society of Hypertension for Clinic, Ambulatory, and Self Blood Pressure Measurement” [1] and JNC 7 [2] , the optimal procedure to measure blood pressure is the following:
Selecting an Accurate Device
List of devices, protocol for use, and details of validation status can be obtained on www.dableducational.org.
Cuff and Bladder Choice
Cuff bladder must enfold ≥ 80% of the measured arm circumference. Miscuffing is a common error during blood pressure measurement. The cuff and the bladder should be chosen according to the size of the arm circumference, as usually detailed by the device protocol. Commonly, such errors target obese patients where cuff size is too small for arm circumference, leading to a phenomenon called “Cuff Hypertension”.
Patient Profile
Special populations require special attention while measuring blood pressure. This includes children, elderly, obese individuals, patients with arrhythmias, and pregnant women. In the latter group, Korotkoff sounds may be heard down to zero mmHg, in which the fourth phase or muffling of sounds should be used to assess diastolic blood pressure.
Explanation to the Patient
This attempts to eliminate patient’s fear that might contribute to a phenomenon called “White Coat Effect”, whereby patients’ blood pressure values are elevated only in the clinic setting. Ambulatory blood pressure measurement helps in identifying the white coat effect (WCE) and white coat hypertension (WCHT).
Comfortable Positioning
Patients should relax silently for a few minutes before blood pressure is measured. Individuals should sit with the back supported, legs uncrossed and cuffed arm positioned at heart level. Likewise, the person conducting the measurement should also be seated comfortably to prevent rapid deflation of the cuff that might underestimate and overestimate systolic and diastolic blood pressures, respectively.
Arm Choice
On the first consultation, patient’s blood pressure must be measured in both arms. Consecutive readings showing differences of > 20 mmHg or > 10 mmHg for systolic and diastolic pressures respectively might suggest an underlying arterial disease that should be ruled out, such as subclavian stenosis. Further blood pressure measurements should be conducted in the arm with the highest values at first assessment if the difference between right and left readings was within normal limits.
Assessment of Postural Hypotension
Due to increasing prevalence, postural hypotension must be assessed by measuring blood pressure when the patient assumes an erect position [3]. Postural hypotension is defined as a systolic blood pressure drop of ≥ 20 mmHg or diastolic blood pressure decrease of ≥ 10 mmHg when the patient stands from a seated position. The presence of postural hypotension suggests in most of the cases impairment in the baroreceptor (firing of afferent nerves and consequential dysfunction of the initiation of autonomic cardiovascular reflex[4]. It is most commonly present in diabetics and elderly. According to the Honolulu Heart Program in 1998, it carries a prognostic value with 64% increase in age-adjusted mortality compared to control population [5]. Intensive blood pressure control then might be compromised due to the presence of orthostatic hypotension, making control of hypertension a bigger challenge in such patients[2].
Common Sources of Error
Technical sources of error include, but are not limited to:
- Misconfigured sphygmomanometer
- Use of low quality or unclean or non-fitting stethoscope
- Inappropriate positioning of the arm
- Inappropriate cuff size for the arm or cuff placed too tight over the arm
- Too rapid deflation of the cuff
- Observer error, digit preference, prejudice, or bias
Ambulatory Blood Pressure Measurement
- Usually 24-hour blood pressure measurement that allows repetitive blood pressure measurement at specified intervals.
- Diagnosis of hypertension is based on average systolic blood pressure ≥ 130 mmHg and/or diastolic blood pressure > 85 mmHg.
- Can identify hidden phenomena like white-coat hypertension (elevated blood pressure only during patient’s visit to clinic) or masked hypertension (normal blood pressure only during patient’s visit to clinic).
- Considered superior to all other techniques in its association with hypertension complications such as target organ damage.
- Most expensive, but still cost-effective.
- Requires interpretation by skilled medical personnel.[2]
Regarding whether the ambulatory pressure should guide treatment, the office pressure may be better.[6]
Self Blood Pressure Measurement
- Normally, two measurements should be obtained each morning and evening for seven consecutive days. First day measurements are to be eliminated. Remaining 24 blood pressure measurements averaged to obtain mean arterial blood pressure
- Diagnosis of hypertension is done based on average systolic blood pressure ≥ 135 mmHg and/or diastolic blood pressure > 85 mmHg
- Can identify hidden phenomena like white-coat hypertension or masked hypertension.
- Superior only to office blood pressure measurement in assessing hypertension complications, such as target organ damage
- More expensive than office blood pressure measurement but less expensive than ambulatory blood pressure measurement[2]
Medical personnel assistance used to be recommended; however with currently available accurate and validated electronic devices, blood pressure measurement became feasible, easy, and dependent only on patient education.
2013 ESH/ESC Guidelines For The Management of Arterial Hypertension (DO NOT EDIT)[7]
Summary of Recommendations on Blood Pressure Measurement (DO NOT EDIT)[7]
| Class I |
| "1. Office BP is recommended for screening and diagnosis of hypertension. (Level of Evidence: B)" |
| "2. It is recommended that the diagnosis of hypertension be based on at least two BP measurements per visit and on at least two visits. (Level of Evidence: C)" |
| Class IIa |
| "1. Out-of-office BP should be considered to confirm the diagnosis of hypertension, identify the type of hypertension, detect hypotensive episodes, and maximize prediction of CV risk. (Level of Evidence: B)" |
| "2. For out-of-office BP measurements, ambulatory blood pressure monitoring; or home blood pressure monitoring may be considered depending on indicaton, availability, ease, cost of use and, if appropriate, patient preference. (Level of Evidence: C)" |
References
- ↑ O'Brien E, Asmar R, Beilin L, Imai Y, Mancia G, Mengden T; et al. (2005). "Practice guidelines of the European Society of Hypertension for clinic, ambulatory and self blood pressure measurement". J Hypertens. 23 (4): 697–701. PMID 15775768.
- ↑ 2.0 2.1 2.2 2.3 Cuddy ML (2005). "Treatment of hypertension: guidelines from JNC 7 (the seventh report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure 1)". J Pract Nurs. 55 (4): 17–21, quiz 22-3. PMID 16512265.
- ↑ Bonny A, Lacombe F, Yitemben M, Discazeaux B, Donetti J, Fahri P; et al. (2008). "The 2007 ESH/ESC guidelines for the management of arterial hypertension". J Hypertens. 26 (4): 825, author reply 825-6. doi:10.1097/HJH.0b013e3282f857e7. PMID 18327095.
- ↑ Leong AS, Wannakrairot P, Jose J, Milios J (1990). "Bacillus Calmette-Guérin-treated superficial bladder cancer: correlation of morphology with immunophenotyping". J Pathol. 162 (1): 35–41. doi:10.1002/path.1711620108. PMID 2231190.
- ↑ Masaki KH, Schatz IJ, Burchfiel CM, Sharp DS, Chiu D, Foley D; et al. (1998). "Orthostatic hypotension predicts mortality in elderly men: the Honolulu Heart Program". Circulation. 98 (21): 2290–5. PMID 9826316.
- ↑ Staessen JA, Den Hond E, Celis H, Fagard R, Keary L, Vandenhoven G; et al. (2004). "Antihypertensive treatment based on blood pressure measurement at home or in the physician's office: a randomized controlled trial". JAMA. 291 (8): 955–64. doi:10.1001/jama.291.8.955. PMID 14982911. Review in: Evid Based Nurs. 2004 Jul;7(3):80
- ↑ 7.0 7.1 Authors/Task Force Members. Mancia G, Fagard R, Narkiewicz K, Redon J, Zanchetti A; et al. (2013). "2013 ESH/ESC Guidelines for the management of arterial hypertension: The Task Force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC)". Eur Heart J. 34 (28): 2159–219. doi:10.1093/eurheartj/eht151. PMID 23771844.