Lax sphygmomanometer standard causes overdetection and underdetection of hypertension: a computer simulation study
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To quantify overdetection and underdetection of hypertension caused by systematic sphygmomanometer errors permitted by the current European standard (EN 1060 'noninvasive sphygmomanometers').We carried out Monte Carlo simulation of measurement of blood pressure (BP) of the adult Australian population using sphygmomanometers showing systematic errors compliant with the EN 1060 standard. We repeated the simulations limiting systematic sphygmomanometer errors to +/-1 mmHg. Simulated BP measurements included systematic sphygmomanometer error, random intraindividual BP variability and random measurement error.After three visits, underdetection of hypertension is common owing to variability of BP measurements and systematic errors of sphygmomanometers. After three visits, the wide tolerances of EN 1060 are responsible for approximately 4.9 and 11% of underdetection of systolic and diastolic hypertension, respectively. Underdetection is worse in some groups, for example, permitted sphygmomanometer error causes 20% of all undetected systolic hypertension in 18-24 year-old women. The current standard also results in overdetection of hypertension. Permitted sphygmomanometer error causes 5.8 and 14% of the overdetection of systolic and diastolic hypertension, respectively, after three visits. Overdetection is worse in some groups, for example, after three visits, permitted sphygmomanometer error causes 19% of falsely detected diastolic hypertension in 18-24 year-old men. For all adults, reduction of permitted sphygmomanometer error to +/-1 mmHg achieves approximately the same improvement in hypertension detection as at least one additional visit to the clinician.Systematic sphygmomanometer errors permitted by the current standard are a preventable cause of clinically significant overdetection and underdetection of hypertension. The standard should be revised to make the effects of equipment related systematic errors negligible compared with the effects of physiological variability.Keywords:
Sphygmomanometer
Systematic error
Blood pressure variability is an important consideration in hypertension trials for determining required sample size and consequently making accurate outcome statements. The Hypertension Prevention Trial was a randomized controlled trial carried out in 1983–1986 in four US clinics on men and women with high normal diastolic blood pressure. This trial provided an opportunity to assess conditions affecting blood pressure measurement variability. Trained blood pressure observers measured systolic and diastolic blood pressures twice, 30 seconds apart, using a random-zero sphygmomanometer. The quality of blood pressure measurements was assessed by computing the variability of the two readings per participant-visit for each blood pressure observer at each study clinic. Other sources of variability investigated included observer digit preference, time of day, and ambient temperature. On the basis of data from this population, it is estimated that the standard deviation of blood pressure values can be reduced by 5% by taking two measurements per participant-visit. An additional reduction of variability can be effected by having the duplicate blood pressure measurements made by different blood pressure observers. In special instances where the range of blood pressure values is very restricted, use of the random-zero sphygmomanometer can increase or decrease the among-participant variability in blood pressure values, depending upon where the distribution of blood pressure values is centered.
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Prehypertension
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To identify possible causes of inaccuracy in the use of the Hawksley random-zero sphygmomanometer and methods that could reduce this.Four Hawksley random-zero sphygmomanometers were compared with a standard sphygmomanometer under static conditions. Two methods (standard and rapid) were used to release pressure from the inflated cuff with pressures recorded by independent blinded observers. The rate at which the hand valve released pressure was analysed. The effects of varying filling times and pressures on the size of the final zero correction were investigated.The Hawksley devices all under-recorded pressure compared with that measured by using a standard machine. A rapid means of pressure release approximately halved this error in each case. Pressure release through the hand valve was shown to have a characteristic and prolonged exponential decay. Using low filling times and pressures reduced the observed range of zeros seen, with the production of a correlation between the size of the zero and the inflation pressure used.These findings suggest that overestimation of the final zero correction is a common and major source of error in the use of the Hawksley sphygmomanometer. A simple change in the design of the final pressure release would improve the machine's reliability in clinical usage. The machine's zero mechanism is susceptible to unintentional misuse. Such misuse could occur when the machine is used in accordance with current sphygmomanometry guidelines.
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Objective To explore the error and causes of measurements of blood pressure by mercyry sphygmomanometer in the patients with hypertension. Methods The arterial blood pressure of 20 hypertensive patients and 20 normal persons were measured by mercyry sphygmomanometer and invasive monitoring simultaneously at 7:00～8:00 am, 6 times each measurement for every person under fasting status. Results In hypertensive patients, the systolic pressure was lower by about 10 mmHg by sphygmomanometer method than by invasive monitoring ( P 0.01), but no difference in diastolic pressure was found between two methods. In normal persons, systolic pressure was lower by about 6 mmHg ( P 0.01 ) and diastolic pressure was higher by about 9 mmHg ( P 0.05). Conclusion There are some errors in measuring blood pressure by sphygmomanometer method. Apparent error is found in systolic pressure in patients with hypertension, but not in diastolic pressure.
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Prehypertension
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Objective To identify possible causes of inaccuracy in the use of the Hawksley random-zero sphygmomanometer and methods that could reduce this. Methods Four Hawksley random-zero sphygmomanometers were compared with a standard sphygmomanometer under static conditions. Two methods (standard and rapid) were used to release pressure from the inflated cuff with pressures recorded by independent blinded observers. The rate at which the hand valve released pressure was analysed. The effects of varying filling times and pressures on the size of the final zero correction were investigated. Results The Hawksley devices all under-recorded pressure compared with that measured by using a standard machine. A rapid means of pressure release approximately halved this error in each case. Pressure release through the hand valve was shown to have a characteristic and prolonged exponential decay. Using low filling times and pressures reduced the observed range of zeros seen, with the production of a correlation between the size of the zero and the inflation pressure used. Conclusion These findings suggest that overestimation of the final zero correction is a common and major source of error in the use of the Hawksley sphygmomanometer. A simple change in the design of the final pressure release would improve the machine's reliability in clinical usage. The machine's zero mechanism is susceptible to unintentional misuse. Such misuse could occur when the machine is used in accordance with current sphygmomanometry guidelines.
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In the case of hypertension patients, monitoring of change in blood pressure and the strain level of the sympathetic nervous system is essentially required. In this study, a method to estimate the systolic and diastolic blood pressure from time-domain parameters of the heart rate variability is proposed. Using this method, it may be possible to monitor blood pressure continuously without posture restriction for a prolonged period of time.Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were estimated from time series of RR intervals during change in posture and compared with those monitored with a portable digital sphygmomanometer. From analysis of data collected on normal subject aged 21-75 years, it was found that DBP and SBP were able to estimate from the heart rate, the parameters evaluating the autonomic function or the autonomic regularity and the age.
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A 55-year-old black man presents for a blood pressure evaluation. He is trying to be more physically active and health conscious but has not seen a physician for five years. He takes no medications, has no concerns, and his physical examination findings are unremarkable. According to the blood pressure monitoring machine at his gym, his blood pressure has ranged from 150 to 160 over 90 to 100 mm Hg over several weeks. Your clinic's technician, using a manual sphygmomanometer on the left arm, measures his blood pressure as 167/95 mm Hg.
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Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels. Accuracy in blood pressure meters is of essence to health, especially in blood pressure monitoring and treatment. The aim of this research was to compare the readings and the sensitivities of some blood pressure monitors in use clinically and privately in Nigeria and the effect of posture on blood pressure. A total of one hundred (100) subjects comprising of fifty (50) males and fifty (50) females all within the age range of 18-30years were involved in this research. Materials used included: stethoscopes, cuffs, aneroid sphygmomanometer, and Omron device. The results indicate statistically significant differences (P<0.05, respectively) when the mercury sphygmomanometer was compared with other blood pressure meters used except the Omron meter. The mean values of systolic blood pressure (SBP) and diastolic blood pressure (DBP) for the meters are (101.70 ± 1.50/69.62 ± 1.46; 107.40 ± 1.19/65.90 ± 1.19; 119.80 ± 2.17/80.89 ± 1.63; 106.10±1.18/74.85±0.91 for aneroid, Omron, wrist and mercury sphygmomanometer respectively. Conclusively, significant variations exist in the sensitivities and accuracies of the different blood pressure meters available for clinical and private use in Nigeria. The need for calibration of all these meters is hereby emphasized.
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This survey assessed the measurement of blood pressure and use of sphygmomanometers by general practitioners in Humberside and Yorkshire in 1988. All registered practitioners were sent a questionnaire--1223 (58%) returned it completed. Their responses showed that 269 (22%) had an aneroid sphygmomanometer only, and that 120 (10%) had a random zero sphygmomanometer; 700 (57%) had special cuffs for obese patients, and 558 (46%) had special cuffs for children; 228 (23.5%) had never had their sphygmomanometers serviced ('never' corresponding to a mean time of 5.75 years), while 23% had patients who measured their own blood pressure. These findings suggest that the British Hypertension Society's recommendations on servicing and cuff use are not always applied. A formal audit of the use of different types of sphygmomanometer in general practice may encourage and improve accuracy and uniformity in blood pressure recording.
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Blood pressure is a measure of how strong the heart is to pump blood around the body. Abnormal blood pressure can occur due to high blood pressure (hypertension) or low blood pressure (hypotension). Data from the World Health Organization (WHO) in 2015 showed that around 1.13 billion people in the world have hypertension, meaning that 1 in 3 people in the world are diagnosed with hypertension. Therefore, a sphygmomanometer was designed that could digitally detect blood pressure and provide food recommendations to stabilize blood pressure. The detection of blood pressure is carried out by the oscillometry method where the oscillation value occurs when blood first flows into the artery after clogging. Systolic blood pressure is determined by multiplying the Mean Arterial Pressure by 0.8. Meanwhile, diastolic blood pressure is determined by multiplying the Mean Arterial Pressure by 0.5. The results of the blood pressure will be displayed on the LCD display and sent to the smartphone. On the smartphone, blood pressure results and food recommendations will be displayed through the android application to make it easier for patients to remember recommended foods and monitor their own blood pressure results without the help of a medical or doctor.
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A random sample of ten community-based Vita-Stat automatic blood pressure recorders (ABPR) was evaluated for accuracy and repeatability. Each of 518 adult volunteers had two randomly ordered systolic and diastolic Vita-Stat blood pressure measurements compared with two corresponding measurements obtained by a trained observer using a Random-Zero sphygmomanometer. Eight of the ten Vita-Stat recorders underestimated systolic blood pressure. In contrast, diastolic blood pressure was overestimated by nine of the ten machines. While the overall differences in average blood pressure were small (mean +/- SEM = -2.4 +/- 0.6 mm Hg for systolic blood pressure and +2.3 +/- 0.4 mm Hg for diastolic blood pressure), the magnitude of the average discrepancy varied considerably by machine (+4.7 to -13.8 mm Hg for systolic and +5.0 to -2.0 for diastolic blood pressure). At every level of systolic and diastolic blood pressure the Vita-Stat ABPR provided a less accurate method of classifying blood pressure among individuals than the human observer. Additional analyses exploring the ability of the Vita-Stat machine to measure an individual's blood pressure within 2, 4, or 6 mm Hg of the corresponding Random-Zero value again suggested that the Vita-Stat ABPR was less accurate than the human observer. Duplicate Vita-Stat readings were less repeatable than corresponding Random-Zero measurements. Based on the findings of this study, the Vita-Stat ABPR appears to be an unsatisfactory tool for community-based self-measurement of blood pressure.
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