Patient-specific differences between blood pressure estimated from 24 h ambulatory measurements and serial office self-recordings

Master blood pressure variation in office, by self, and in sleep recordings

Variation inherent to each session in any recording situation has to be mastered to obtain informative mean values and differences. Variation due to time trend and unsteady consecutive readings versus inter-arm variations in blood pressure (BP) in the operator-initiated, self-initiated, and sleep recordings were studied by oscillometry. They were small in operator-initiated recordings, increased in self-recordings, and were paramount in sleep. A passive supine patient and simultaneous recordings with cuffs placed in equal horizontal positions are essential conditions for the estimation of a real mean inter-arm difference. The relative variation of pulse pressure (PP), compared with other components, was largest within each situation. Most of the systolic BP (SBP)/diastolic BP (DBP) variation in sleep was due to unequal vertical cuff distances to the heart level. Only sleep PP was independent of the vertical position of cuffs. A plot of inter-arm differences can visualize systematic errors in sequences of sleep SBP/DBP. As is well known, every doubling of variation (SD) requires quadrupling the number of independent recordings in order to retain the same size of confidence interval (CI) for a mean value.

The BpTRU automatic blood pressure monitor compared to 24 hour ambulatory blood pressure monitoring in the assessment of blood pressure in patients with hypertension

BACKGROUND

Increasing evidence suggests that ABPM more closely predicts target organ damage than does clinic measurement. Future guidelines may suggest ABPM as routine in the diagnosis and monitoring of hypertension. This would create difficulties as this test is expensive and often difficult to obtain. The purpose of this study is to determine the degree to which the BpTRU automatic blood pressure monitor predicts results on 24 hour ambulatory blood pressure monitoring (ABPM).

METHODS

A quantitative analysis comparing blood pressure measured by the BpTRU device with the mean daytime blood pressure on 24 hour ABPM. The study was conducted by the Centre for Studies in Primary Care, Queen's University, Kingston, Ontario, Canada on adult primary care patients who are enrolled in two randomized controlled trials on hypertension. The main outcomes were the mean of the blood pressures measured at the three most recent office visits, the initial measurement on the BpTRU-100, the mean of the five measurements on the BpTRU monitor, and the daytime average on 24 hour ABPM.

RESULTS

The group mean of the three charted clinic measured blood pressures (150.8 (SD10.26) / 82.9 (SD 8.44)) was not statistically different from the group mean of the initial reading on BpTRU (150.0 (SD21.33) / 83.3 (SD12.00)). The group mean of the average of five BpTRU readings (140.0 (SD17.71) / 79.8 (SD 10.46)) was not statistically different from the 24 hour daytime mean on ABPM (141.5 (SD 13.25) / 79.7 (SD 7.79)). Within patients, BpTRU average correlated significantly better with daytime ambulatory pressure than did clinic averages (BpTRU r = 0.571, clinic r = 0.145). Based on assessment of sensitivity and specificity at different cut-points, it is suggested that the initial treatment target using the BpTRU be set at <135/85 mmHG, but achievement of target should be confirmed using 24 hour ABPM.

CONCLUSION

The BpTRU average better predicts ABPM than does the average of the blood pressures recorded on the patient chart from the three most recent visits. The BpTRU automatic clinic blood pressure monitor should be used as an adjunct to ABPM to effectively diagnose and monitor hypertension.

Blood pressure measurement in research and in clinical practice: recent evidence

PURPOSE OF REVIEW

For over a century the technique of blood pressure measurement developed by Riva-Rocci and Korotkoff has provided most of the data on hypertension diagnosis and treatment. Its limitations, however, are becoming increasingly evident and therefore alternative solutions are under investigation. This paper is intended to provide an overview of important recent progress in this field, and to highlight future perspectives.

RECENT FINDINGS

A major development in blood pressure measurement is the technical improvement of electronic manometers for use either in the clinic (with the auscultatory approach, as an alternative to use of mercury columns), or in automated oscillometric devices yielding blood pressure measurements devoid of observer-dependency, and allowing long-term blood pressure monitoring. In the latter case, blood pressure measurement is made possible in settings other than the physician's office, either through ambulatory blood pressure monitoring or through self blood pressure measurement at home. These methods are growing in clinical importance, but further studies are needed to define their indications more precisely in the clinical evaluation of hypertensive patients. Recently, important steps towards better standards of blood pressure measurement have been taken, as summarized in the guidelines jointly issued by the European Society of Hypertension (ESH) and the European Society of Cardiology (ESC), in the 7th Joint National Committee Report and (in even more detail) in the Blood Pressure Measurement Guidelines published by the ESH Working Group on Blood Pressure Monitoring.

SUMMARY

Blood pressure measurement is a rapidly developing field, the importance of which is increasingly acknowledged in the light of the growing awareness of the impact of hypertension on public health. Despite remarkable progress, many methodological issues still remain to be properly addressed.