Fainsia Mee

Accuracy of the SpaceLabs 90207 determined by the british hypertension society protocol

Results: The three recorders passed the before-use interdevice variability assessment, after which 84% of inflations recorded with these devices during the in-use phase gave valid readings, and the three devices subsequently passed the after-use interdevice variability assessment. The main validation test was carried out on one device in 86 subjects with a wide range of pressures, the results being analysed according to a grading system from A to D. The SpaceLabs 90207 acheived B rating for both systolic and diastolic pressures and also satisfied the criteria for accuracy of the Association for the Advancement of Medical lnstrumentation (AAMI), with an average difference (f s.d.1 of 1 f 7 and 3 f 6 mmHg for systolic and diastolic pressure, respectively. Subject acceptability was good. The manufacturers manual was satisfactory overall, but contained a number of errors and omissions.

Use and interpretation of ambulatory blood pressure monitoring: recommendations of the British Hypertension Society

Over the past 20 years or so, the accuracy of using the conventional Riva-Rocci sphygmomanometer and Korotkoffs sounds to measure blood pressure has been questioned, and efforts have been made to improve measurements with automated devices.1 2 In the same period, the phenomenon of white coat hypertension has been recognised—whereby some patients who apparently have raised blood pressure actually have normal blood pressure when the measurement is repeated away from the medical environment; this has focused attention on methods of measurement that provide profiles of blood pressure rather than rely on isolated measurements made under circumstances that may influence blood pressure.3 These methods have included repeated measurements of blood pressure using the traditional technique, self measurement of blood pressure in the home or workplace, and ambulatory blood pressure measurement using automated devices.2 Ambulatory monitoring is advantageous because it gives multiple measurements throughout the day and night This paper considers only the ambulatory measurement of blood pressure in adults. Its purpose is not to make a case for or against ambulatory measurement; others have already done so.4 5 Although the results of a number of ongoing, longitudinal studies are forthcoming, there is now firm evidence that ambulatory blood pressure measurement is a more sensitive predictor of cardiovascular outcome than conventional measurement.6 We have not considered the complex issues of health economics that the increasing use of ambulatory measurement raises.7 We realise that this technique is being used more often and that doctors who find ambulatory measurement useful in the day to day management of patients with high blood pressure need recommendations from those who have experience. However, regardless of the technique used to diagnose hypertension it is only one factor in determining a patients risk profile and must be assessed in relation to concomitant disease, …

A method of quantifying retinal microvascular alterations associated with blood pressure and age

Objective To find an objective, sensitive method for quantifying microvascular alterations associated with level of blood pressure and age. Design A prospective cross-sectional study. Subjects and methods Seventy-four previously untreated hypertensive patients, referred to a hospital outpatients department, and 26 normotensive volunteers participated. Twenty-four-hour ambulatory blood pressure monitoring and bilateral fundal photography were performed. The fundal photographs were projected on a screen such that the optic disc filled a circle of radius 5 cm. Microvessels crossing the border of a concentric circle of radius 20 cm were identified as arteriolar or venular, counted and their luminal diameters measured. Main outcome measures Arteriolar and venular numbers, mean diameters and vascularities (arteriolar and venular vascularities defined as the sum of arteriolar and venular diameters, respectively). Results The technique was reproducible. As blood pressure increased, arteriolar vascularity declined and venular vascularity increased. These associations resulted in a strong inverse correlation between blood pressure level and the ratio arteriolar vascularity: venular vascularity (r = 0.48, P<0.001). Arteriolar number declined with increasing diastolic blood pressure (r = 0.22, P<0.05). Mean arteriolar diameter appeared to have a U-shaped relationship with diastolic blood pressure levels (r = 0.27, P<0.05). Venular dilation was associated with increasing blood pressure levels (r = 0.22, P<0.05). Mean arteriolar and venular diameters declined significantly with age (r = 0.33 and 0.26, respectively; P<0.01) and there was no association between arteriolar vascularity: venular vascularity ratio and age. Conclusions The method detected disparate retinal microvascular alterations with age and blood pressure. The arteriolar vascularity: venular vascularity ratio shows promise as a non-invasive, prognostic and therapeutic guide in hypertension.

Comparative accuracy of six ambulatory devices according to blood pressure levels

Objective: To assess the accuracy of six ambulatory blood pressure measuring systems at low, medium and high blood pressures. Results: The CH-Druck, Profilomat, SpaceLabs 90207 and Novacor DIASYS 200R, having previously achieved A to C grading for systolic and diastolic blood pressures according to the British Hypertension Society (BHS) protocol and having fulfilled the criteria of the Association for the Advancement of Medical Instrumentation, have been recommended for measurement of ambulatory blood pressure in clinical practice; the Pressurometer IV and Takeda TM-2420, achieved only C and D grades and failed to satisfy the Association for the Advancement of Medical Instrumentation criteria. In this study the data from the original validations are re-analysed for three pressure ranges of systolic and diastolic blood pressures: low range ≤ 130/80 mmHg, medium range 130-160/80-100 mmHg and high range ≥ 160/100 mmHg. All six devices maintained their overall grading or improved them slightly in the low and medium blood pressure ranges, but in the high blood pressure range the CH-Druck slipped from an overall A/A grading to B/C, the Profilomat from B/A to C/D, the SpaceLabs from B/B to C/C and the Pressurometer IV from C/D to D/D. The Takeda remained unchanged with a D grading, but the results within this grading were worse in the higher blood pressure range, and the Novacor rose from C/C to C/B. Conclusions: This analysis suggests that the CH-Druck is the most accurate ambulatory system across the pressure range, although it does not perform as well in the high blood pressure range as in the medium and low blood pressure ranges. The SpaceLabs 90207 is accurate in the low and medium blood pressure ranges and reasonably accurate in the high blood pressure range. If blood pressures only in the low and medium ranges are to be measured, a wider selection of ambulatory systems becomes available because, in addition to the CH-Druck and SpaceLabs 90207, the Profilomat and Novacor DIASYS 200R are accurate.

Evaluation of the Schiller BR-102 ambulatory blood pressure system according to the protocols of the British Hypertension Society and the Association for the Advancement of Medical Instrumentation.

OBJECTIVE To evaluate the Schiller BR-102 monitor for ambulatory blood pressure measurement according to the protocols of the British Hypertension Society (BHS) and the Association for the Advancement of Medical Instrumentation (AAMI). DESIGN The BHS protocol is divided into two parts. Part I, which is the part applicable to this study, comprises the main validation procedure and has five phases: before-use device calibration; in-use (field) phase; after-use device calibration; static device validation; and report of evaluation. METHOD Three Schiller BR-102 recorders passed the before-use device calibration test, after which they entered the in-use (field) assessment phase during which the three recorders were each worn by 10 subjects for 24 h, after which calibration was again assessed. Because there was no difference in results of calibration testing among the three devices, one was selected randomly and the main validation test was carried out on 85 subjects with a wide range of blood pressures both for the auscultatory mode and for the oscillometric mode using the Sphygmocorder. The results were analysed according to the BHS grading system from A to D. The data were also analysed according to the standard of the Association for the Advancement of Medical Instrumentation (AAMI), which stipulates that the mean difference between the test device and the standard shall be </= 5 mmHg with a standard deviation of </= 8 mmHg. RESULTS The Schiller BR-102 achieved a BHS grade B rating for systolic and diastolic blood pressures in the auscultatory mode and satisfied the criteria for accuracy of the AAMI protocol for systolic and diastolic blood pressures. In the oscillometric mode, the Schiller BR-102 achieved grade D for systolic blood pressure and grade B for diastolic blood pressure according to the BHS protocol and satisfied the AAMI criteria for diastolic but not systolic blood pressure. Applying the BHS and AAMI criteria to tertiles of blood pressure (low-pressure range < 130/80 mmHg, medium-pressure range 130-160/80-100 mmHg, high-pressure range > 160/100 mmHg) the Schiller BR-102 was less accurate in the high pressure range for diastolic blood pressure but more accurate for systolic blood pressure, achieving A/C grading, while satisfying the AAMI criteria both for systolic and for diastolic blood pressure in the auscultatory mode. In the oscillometric mode the device performed less accurately in the high-pressure range, achieving grade D/C, while failing to satisfy the AAMI criteria both for systolic and for diastolic blood pressure. The means+/-SD of the first mercury sphygmomanometer measurements were 143+/-32 mmHg for systolic blood pressure and 88+/-21 mmHg for diastolic blood pressure. Acceptability to subjects was good and the manufacturers manual was satisfactory. CONCLUSION On the basis of these results, the Schiller BR-102 can be recommended for ambulatory blood pressure measurement in clinical practice using the auscultatory mode, but the oscillometric mode, which operates only if the device fails in the auscultatory mode, does not provide accurate measurements.

Short report: Accuracy of the Ch-druck/pressure Scan Erka ambulatory blood pressure measuring system determined by the British Hypertension Society Protocol

Objective: To evaluate the CH-Druck/Pressure Scan ERKA monitor for ambulatory blood pressure measurement according to the British Hypertension Society (BHS) protocol. Design: The BHS protocol consists of six phases: I, observer training and assessment; II, before-use interdevice variability assessment; Ill, in-use assessment; IV, after-use interdevice variability assessment; V, device validation; and VI, preparation of report. Method: Three CH-Druck/Pressure Scan ERKA recorders passed the before-use interdevice variability test, after which 89% of inflations recorded with these devices during the in-use phase gave valid readings, and the three devices subsequently passed the after-use interdevice variabilty test. The main validation test was carried out in 86 subjects with a wide range of pressures, the results being analysed according to the BHS grading system from A to D. Results: The CH-Druck/Pressure Scan ERKA acheived a grade A rating for both systolic and diastolic blood pressure, and satisfied the criteria for accuracy of the Association for the Advancement of Medical lnstrumentation (AAMI) with a mean difference (+ SD) for systolic pressure of - 3k 4 mmHg and - 21t 4 mmHg for diastolic pressure between the test device and the mercury sphygmomanometer. Subject acceptability was good and manufacturers manual was satisfactory. Conclusion: On the basis of these results, the CH-DrucWPressure Scan ERKA can be recommended for ambulatory blood pressure measurement in clinical practice.

A Longitudinal Study of the Yield and Clinical Utility of a Specifically Designed Secondary Hypertension Investigation Protocol

Objective. It has become common practice to use a day-case based approach to identify from the population of hypertensive patients those with an identifiable cause. We aimed to prospectively identify 96 consecutive hypertensive patients undergoing an algorithmic investigation protocol based around two day case hospital attendances. Methods. The overall diagnostic yield and associated costs were recorded and the patients were observed for a mean of 2.5 years with ambulatory blood pressure (BP) monitoring every three months. Results. A secondary cause of hypertension was identified in 18.1% of patients, three quarters of whom had renovascular disease. There was a fall in blood pressure with time (157/97 vs. 140/85) but this was associated with an increase in the amount of medication required (mean medication score 5.99 vs. 7.65). Improvement in BP occurred irrespective of whether or not a secondary cause was identified. Only 3.2% of patients were cured of their hypertension as a result of enrollment in the protocol. The cost of identifying each case of secondary hypertension was Euro 10, 196. Conclusions. A comprehensive protocol aimed at identifying secondary hypertension had a low yield, the majority of whom had renovascular disease. In light of recent data illustrating the lack of improvement in BP following dilatation or bypass of atherosclerotic renovascular disease, it is debatable whether searching for it is justifiable.