Accurate blood pressure measurement: why does it matter?

• Published in: Canadian Medical Association journal (CMAJ) 1999-08, Vol.161 (3), p.277-278
• Main Authors: Campbell, N R, McKay, D W
• Format: Article
• Language: English
• Subjects: Blood pressure; Blood Pressure - physiology; Blood Pressure Determination - standards; Blood Pressure Monitoring, Ambulatory - standards; Humans; Hypertension - diagnosis; Nursing; Reproducibility of Results; Sensitivity and Specificity; Stress, Psychological; Testing
• ISSN: 0820-3946; 1488-2329

Measurement of a patient's blood pressure is one of the most common and basic medical assessments. However, errors in measuring blood pressure occur often. Most errors result in overestimates of blood pressure, which could cause almost twice as many patients' receiving the diagnosis of hypertension as actually have high blood pressure. In other cases, hypertension is likely underdiagnosed owing to underestimates of blood pressure. Many errors result in variability of readings and cause confusion regarding blood pressure status. "Casual" readings -- those obtained with little attention to patient factors or recommended technique -- cause errors in blood pressure assessment and are not highly correlated with target organ damage. Currently no evidence exists to support the use of casual readings in assessing a patient's need for pharmacologic treatment. Conversely, standardized readings - those that follow recommended protocols - correlate with hypertensive target organ damage and were used in the major randomized controlled trials that showed the benefits of pharmacotherapy. Equipment problems or misuse occur often too. Most physicians still use a regular-sized cuff to measure blood pressure in patients with large arms.1 In patients whose arm circumference is best suited for a large cuff, the use of a regular-sized cuff causes consistent overestimation of diastolic blood pressure by approximately 6 mm Hg.6 Inaccurate sphygmomanometers are also common: 30% to 40% of aneroid sphygmomanometers used by physicians are out of calibration by 4 mm Hg or more, and about 10% are out of calibration by 10 mm Hg or more.1 Inadequate preparation of patients, significant deviations from recommended technique and inaccurate sphygmomanometers often result in blood pressure measurement errors of 10 mm Hg or more.1 Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure. The sixth report of the Joint National Committee on Prevention, Detection, Evaluation and Treatment of High Blood Pressure. Arch Intern led 1997;157:2413-46. Haynes RB, Lacourciere Y, Rabkin SW, Leenen FHH, Logan AG, Wright N, et al. Report of the Canadian Hypertension Society Consensus Conference: 2. Diagnosis of hypertension in adults. C.Nt 1993;149(4):409-18. Campbell NRC, Chockalingam A, Fodor JG, McKay DW. Accurate, repro ducible measurement of blood pressure. CMA,7 1990;143 ( 1):19-24.