Rapid oscillometric blood pressure measurement compared to conventional oscillometric measurement.

BACKGROUND: There have been few reports studying the necessary interval between blood pressure measurements, after the initial rest period. METHODS: Blood pressure was measured in 50 patients using the conventional oscillometric technique (COT) and the rapid oscillometric technique (ROT). RESULTS: The difference between COT and ROT was -1.1 / -0.1 mmHg, which was not significantly different (p = 0.8 / 1.0) and the pulse difference was -0.8 beats per minute (p = 0.8). CONCLUSIONS: It is concluded that a 15-second interval between blood pressure readings is as accurate as a one-minute interval providing that these measurements are started after a 5-minute rest period.

Accuracy of aneroid sphygmomanometers in clinical usage: University of Michigan experience.

BACKGROUND: Aneroid manometers are frequently used to measure blood pressure. Aneroid manometers have moving parts that are subject to fatigue. The accuracy duration of the aneroid devices, like most digital devices, is unstudied. It has been accepted that if the aneroid device does not rest at '0' it is inaccurate, but how often is the device inaccurate when it does rest at '0'? METHODS: A Universal Biometer DPM-III measuring unit was used for all of the measurements at 10 University of Michigan Health System sites. A total of 136 aneroid manometers were tested. Two additional aneroid devices were not tested, as the needle did not start within '0'. Static pressure measurements were made at nine levels for all devices: 50, 80, 90, 100, 120, 150, 200 and 250mmHg. RESULTS: The average difference of the nine pressure settings of the whole group was 0.2+/-0.31 (95% confidence interval 0.1-0.2) mmHg. The largest number of devices that were not calibrated within +/-3mmHg was seen at the 150mmHg setting with six (4.4%) of the devices failing. If an accuracy standard of +/-2mmHg was used, the largest number of devices failed at 250mmHg (22 devices, 16.2%). The largest number of devices that were inaccurate was manufactured 6 years prior to testing and was from two sites. CONCLUSIONS: Aneroid devices were accurate. A yearly calibration programme should be performed and a +/-2mmHg standard should be used. Portable aneroid manometers may need to be more frequently calibrated due to the trauma associated with dropping.

Home blood pressure monitoring.

Hypertension is estimated to affect 43 to 56 million adults or 24% to 31% of the US population and is emerging as a major health problem in some countries in the Third World. Hypertension contributes to all the major atherosclerotic cardiovascular disease outcomes.

Measurement variation among 12 electronic home blood pressure monitors.

Although there are AAMI and BHS standards for accuracy of electronic home electronic blood pressure monitors (HBPM), patient composition differences and differences in manufacturer's algorithm for calculation of the systolic and diastolic measurement may result in measurement differences between monitors. The aim of this study was the measurement of differences among HBPM. Paired comparisons were performed between the Omron 712c electronic home monitor and each of 12 other HBPM (Sunbeam 7654, Sunbeam 7623, Omron 711, Omron 432c, A&D-UA767, Lumiscope 1085M, Omron 725CIC, Assure A30, Lumiscope 1083N, Omron 815, Omron 605, and Assure BD-W20), in addition to comparison to the auscultatory method by trained observers. Measurements were made in normotensive subjects in an ambulatory setting. The main outcome measures were systolic and diastolic blood pressure measurements. All of the HBPM, except for the Sunbeam 7654 and the Assure A30/ BD-W20 (wrist) models, demonstrated small differences of <4/4 mm Hg for systolic/diastolic measurements with pulse measurement differences of <3 beats/min. These differences were less than the differences previously reported for office BP auscultation of 6/5-10 mm Hg for systolic/diastolic measurements. The Omron 712c, passing previous AAMI and BHS standards, measured the systolic reading within 2 mm Hg of auscultatory mercury or aneroid measurement and under-measured the diastolic by 6-9 mm Hg. Differences in the patient composition studied could account for the difference. The wrist and finger manometers performed clinically similar to the Omron 712c, except for the Assure BD-W20, which overmeasured the diastolic by 7 mm Hg. It is concluded that the small differences among the various HBPM, which are less than those in clinical office auscultation, should encourage greater use of electronic manometers in the office and at home.

Determination of accuracies of 10 models of home blood pressure monitors using an oscillometric simulator.

BACKGROUND: Patients and doctors often use home blood pressure monitoring (HBPM) to assess the control of hypertension. Despite its popularity there has always been some uncertainty with regard to its accuracy, reliability, reproducibility, and comparability. Although there are pre-market HBPM standards of accuracy, there are no standards to assure accuracy of individual HBPM units after they have been brought home. OBJECTIVE: Determination of reliability, reproducibility, and comparability of 10 models of home blood pressure monitors. METHODS: We used a Biotek BP Pump as an oscillometric simulator of systolic and diastolic blood pressures to determine reliability, reproducibility, and comparability of 10 devices. RESULTS: All of the units tested, except the Pollonex BP1000, produced reproducible readings with the pooled SD of four blood pressure settings less than 3.10 mmHg both for systolic and for diastolic measurements. The oscillometric blood pressure pump method was found to be very reproducible, with pooled differences of less than 2 mmHg and SD of less than 0.5 mmHg for a repeated series of measurements using the same monitor. Different machines of the same model were also very comparable, with pooled differences of less than 3.6 mmHg and pooled SD less than 0.7 mmHg both for systolic and for diastolic readings. There were 11-14 mmHg differences between models for all of the simulated blood pressure readings except that a 27 mmHg difference was measured at the 200 mmHg systolic blood pressure level. These differences will not necessarily be the same for measurements with humans instead of oscillometric signal generation. A system for grading the accuracy of the tested HBPM that defines accuracy of HBPM as within +/-2 SD of the average of 85 measurements is described. CONCLUSION: All models of home blood pressure monitors tested, with the exceptions of the Pollonex BP1000, produced reproducible readings and different machines of the same model were comparable.

Sodium concentration of water from softeners.

OBJECTIVES: To determine whether water is safe for consumption after it has passed through a water softener and whether there are any health and environmental implications of cationic water softeners. METHODS: Sodium concentration was measured in 59 water samples that had passed through a water softener and was compared with the sodium concentration of 5 samples from 4 different local municipal sources. RESULTS: The mean +/- SD sodium concentration of softened well water was 278 +/- 186 mg/L (range, 46-1219 mg/L). There were 10 (17%) households with sodium levels greater than 400 mg/L. The mean +/- SD sodium concentration of municipal, nonsoftened water was 110 +/- 98 mg/L (range, 0-253 mg/L). CONCLUSIONS: Softened well water in our area on average contained a 2.5-times-higher concentration of sodium than local municipal water, comparable with previous reports. It is unlikely that the increased sodium from softened water would have any health risks for most people. This may not be true for people on severely sodium-restricted diets.

Cost effectiveness of 24-hour ambulatory blood pressure monitoring in evaluation and treatment of essential hypertension.

We wanted to determine if use of ambulatory blood pressure monitoring (ABPM) was cost effective, preventing unnecessary drug therapy in patients misdiagnosed as having essential hypertension, with elevated office blood pressures and normal ambulatory blood pressure. To address this issue we surveyed costs to the patient for antihypertensive drug therapy in 1990 of five local pharmacies in southeastern Michigan. Patients studied (n = 192) were seen in a private, general internal medicine practice in rural southeastern Michigan and received ABPM to assess the presence of hypertension and the adequacy of blood pressure treatment. We ascertained the average, minimal, and maximal drug cost to the patient per unit dose at the local pharmacies. The average yearly cost for patients on antihypertensive medications at pharmacies in southwestern Michigan was $578.40, with figures varying from $94.90 to $4361.75. Although there is no standard reimbursement amount for ABPM, at $188 per monitoring, the cost of monitoring this entire group of patients would offset exactly the cost of medication for the group of patients found to have only office hypertension. As such, third-party insurance carriers should consider reimbursement for ABPM in hypertension to decrease pharmaceutical cost and its attendant potential side effects. In conclusion, our study results suggest that ABPM is cost effective in an outpatient setting in preventing unwarranted drug therapy and the inappropriate diagnosis of hypertension.

Ambulatory blood pressure monitoring in a nonacademic setting. Effects of age and sex.

Twenty-four-hour ambulatory blood pressure measurements (ABPM) are likely to eliminate the stress of visits and observer bias in office blood pressure (BP) recordings, allow consideration of the circadian variability in BP, and correlate well with target organ damage. To define the prevalence of "white coat" hypertension in a rural community to a nonacademic setting, and to assess age and sex related differences, we studied 131 patients who had more than two prior office diastolic BP measurements greater than 90 mm Hg and less than 115 mm Hg. Blood pressure was measured every 10 to 60 min for 24 h using the SpaceLabs 90207 device. Office BP readings were higher than ABPM in the group as a whole, in individual age groups, and in both sexes. The differences were more pronounced at night. Average differences between office and ambulatory BP ranged between 14.4 +/- 1.7/2.9 +/- 2.0 (ABPM at 10:00), and 33.8 +/- 2.3/22.8 +/- 1.5 mm Hg (systolic/diastolic +/- SE) (ABPM at 01:00). The nighttime drop in systolic BP was not apparent in subjects more than 65 years old. Women had a proportionately higher mean office BP than men (115.0 +/- 0.9 office v 110.2 +/- 1.3 mm Hg ABPM in women and 112.3 +/- 0.9 v 104.3 +/- 1.1 mm Hg in men) (P = .013), and the elderly did not display the relationship between ambulatory and office mean BP seen in younger subjects (r = 0.15, P = .30 v r = 0.36, P = .0004, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)