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(Hypertension. 1995;26:912-918.)
© 1995 American Heart Association, Inc.

Articles

A Consensus View on the Technique of Ambulatory Blood Pressure Monitoring

Jan A. Staessen; Robert Fagard; Lutgarde Thijs; Antoon Amery¹; and the Participants in The Fourth International Consensus Conference on 24-Hour Ambulatory Blood Pressure Monitoring

From The Fourth International Consensus Conference on 24-Hour Ambulatory Blood Pressure Monitoring. A complete list of the participants appears at the end of this article.

Correspondence to Jan A. Staessen, MD, PhD, Klinisch Laboratorium Hypertensie, Inwendige Geneeskunde-Cardiologie, U.Z. Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.

	Abstract

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
Abstract This review, based on the Fourth International Consensus Conference on Ambulatory Blood Pressure Monitoring (Leuven, Belgium, 1994), deals with the technical aspects of ambulatory blood pressure monitoring. Ambulatory blood pressure monitoring by noninvasive intermittent techniques is widely used despite artifacts due to cuff size, movement, body position, short-term blood pressure variability, and interference with sleep. The performance of the currently available monitors under truly ambulatory conditions and during exercise remains a matter of debate, as are the procedures required to validate portable monitors under these circumstances. There is general agreement that whenever a monitor is to be used in special populations, such as older subjects or pregnant women, or in special conditions, such as exercise, a specific demonstration of its accuracy in these defined subgroups or conditions is warranted. Whether the auscultatory or oscillometric method is preferred remains controversial because each technique has specific advantages and disadvantages and because both can provide accurate results. Most experts in the field strongly believe that manufacturers should disclose the algorithms of their devices and that they should specify all changes made to the hardware and software of a previously validated monitor. Finally, the development of the volume-clamp method, which makes continuous noninvasive registration of blood pressure at the finger possible in both stationary and ambulatory conditions, opens new perspectives in research, in particular in relation to short-term blood pressure variability.

Key Words: blood pressure monitoring, ambulatory • blood pressure determination • blood pressure monitors

	Introduction

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
The technique of noninvasive ambulatory blood pressure monitoring is rapidly expanding as both an instrument in clinical research and a diagnostic tool in clinical practice. This article reflects the common ground that emerged on technical issues at the Fourth International Consensus Conference on Ambulatory Blood Pressure Monitoring (Leuven, Belgium, 1994) and highlights some key areas that stayed contentious and should be subject to further research.

	Cuff Size

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
Cuff size relative to arm circumference is an important determinant of the accuracy of noninvasive pressure measurements.¹ The 1993 World Health Organization/International Society of Hypertension memorandum advised that cuffs for adults should have a bladder width of 13 to 15 cm and a bladder length of 30 to 35 cm.² Larger cuffs were recommended for fat arms, and smaller cuffs for children.² The JNC V guidelines proposed that the inflatable part of the cuff, that is, the bladder, should nearly (at least 80%) or completely encircle the arm.³ There is no reason why these recommendations would not be applicable to automated blood pressure readings by portable ambulatory monitors.

In 14% of a random population sample aged 20 to 88 years, arm circumference exceeded 32 cm.⁴ These findings highlight the necessity of using large cuffs in a substantial number of subjects. Manufacturers should therefore provide ambulatory monitors that include large cuffs as a standard part of the equipment. The energy supply and pumps of the portable monitors should be adequate to inflate these bigger cuffs at the shortest interval possible. Whenever ambulatory monitoring is carried out in conjunction with conventional readings, both should be performed with cuffs and bladders of the same size so that comparisons between the results of both types of measurement can be possible.

	Position of the Arm

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
A second factor that is possibly limiting the accuracy of ambulatory monitors is the position of the arm relative to the heart when the blood pressure is taken.^{5 6} On average, pressure increases by about 5 mm Hg as the arm moves down from a horizontal to a hanging position.⁵ The position of the arm is difficult to standardize during ambulatory monitoring because this requires subject cooperation. Measurement error caused by the position of the upper arm may be prevented during the day by asking subjects to ensure that the arm is always parallel to the trunk when the cuff is inflated. However, this is not feasible at night. During sleep, blood pressure may be 10 mm Hg lower when subjects are lying with the monitored arm above the heart level, as opposed to lying on the contralateral side.⁶

	Short-term Blood Pressure Variability

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
Short-term blood pressure variability potentially limits the accuracy of intermittent noninvasive monitoring.^{7 8 9} The Milan group addressed this issue by progressively abridging a beat-to-beat analysis of 24-hour intra-arterial recordings to samples taken at progressively widening intervals.^{7 8} There was close agreement between the 24-hour pressure averages obtained by either a beat-to-beat analysis or intermittent sampling of the recordings at 5 minutes up to 30 minutes. Only at 60-minute intervals, the 24-hour pressure deviated in a few individuals by as much as 5 to 15 mm Hg from the averages calculated from the entire intra-arterial recording. Nevertheless, even with sampling at 60-minute intervals, the difference with the beat-to-beat analysis in all subjects combined averaged only 1 mm Hg for both systolic and diastolic pressures. By contrast, blood pressure variability as assessed by the within-subject standard deviation of intermittent readings deviated considerably from the beat-to-beat analysis once the sampling interval was 15 minutes or longer.^{7 8} Thus, noninvasive intermittent monitoring makes an accurate determination of blood pressure level possible in most cases, whereas short-term blood pressure variability is more difficult to estimate.

	Disturbance of Sleep

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
Wearing a blood pressure monitoring device during sleep with cuff inflations programmed to occur at 10-minute^{10 11} or 30-minute¹² intervals causes a reduction of slow-wave (non-REM) sleep and longer nocturnal awakenings.^{10 11 12} It has also been suggested that ambulatory blood pressure machines would cause appreciable arousal from sleep, associated with a transient increase in systolic pressure averaging 5 to 15 mm Hg.¹² However, the latter contentions were based on a study of only six patients,¹² in whom sleep quality, assessed by a single electroencephalogram, was not directly compared during nights with and without noninvasive blood pressure monitoring. In contrast, Degaute et al¹⁰ observed that the number of awakenings was the same on four nights, including the one during which blood pressure was recorded by the occluding cuff method. Nevertheless, in the latter study¹⁰ the duration of the nocturnal awakenings was lengthened, suggesting that once the volunteers had been aroused, the auditory and tactile stimuli produced by the recorder retarded the reappearance of sleep. This phenomenon may contribute to the disappointingly low reproducibility¹³ of the so-called dipper versus nondipper state. The duration of nocturnal sleep diminishes with advancing age,¹⁴ but the alteration of sleep induced by noninvasive monitoring probably does not.¹⁰

Manual inflation of a cuff in the case of self-measurement may lead to a small and transient rise in blood pressure.¹⁵ By contrast, researchers who used simultaneous continuous recordings as a reference have demonstrated that the automated or semiautomated inflation of a cuff does not necessarily lead to a pressor effect.¹⁶ In addition, there is large interindividual variability in the nightly awakenings caused by noninvasive monitoring.^{10 11 12} Thus, in general, ambulatory monitoring does not change the average nighttime pressure, so group means can be reliably reproduced.¹³

Interference with sleep also seems to vary among devices.¹² Predictably, it increases with the noise generated by the recorder but also by the rate of cuff inflation and deflation⁹ and by the height of the pressure to which the cuff needs to be inflated to occlude the brachial artery,¹⁷ that is, by factors determining the duration and intensity with which the upper arm is compressed.

	Performance During Ambulatory Conditions

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
The performance of noninvasively functioning ambulatory monitors tends to be poorer under ambulatory conditions, in the working environment, and during exercise than at rest.^{18 19 20 21} Contraction of the upper arm musculature, movement of the arm and the body as a whole, the unsteady position of the arm vis-à-vis the heart level,^{5 6} and the possible displacement of the cuff all produce artifacts that during cuff deflation are superimposed on both the arterial pressure waves and the background pressure in the cuff. These artifacts often remain undetected by the algorithms. Moreover, auscultatory devices are hindered by the noise produced by muscle contraction and environmental sources. The accuracy of auscultatory monitors may be improved by various techniques, such as the use of R wave gating,²² multiple microphones,²² or waveform analysis and pattern recognition of the Korotkoff sounds (K2 algorithm).²³ The latter technique, however, has not yet been commercially developed.

Validation of noninvasive monitors under truly ambulatory conditions has been proposed.¹⁸ However, sphygmomanometric measurements, which are the standard for validation of portable monitors in resting subjects in the laboratory, cannot be used as a reliable reference during exercise and ambulation because of their relative imprecision.²¹ The guidelines of the British Hypertension Society do not recommend the routine comparison of indirect and intra-arterial blood pressure measurements for obvious ethical reasons.^{24 25} Moreover, the systolic and diastolic pressure values obtained by the direct technique are different from those obtained by the indirect method, which so far have been used to establish the epidemiological and clinical criteria for the management of hypertensive patients. However, the latter criteria are applicable only to subjects examined at rest. More important, under ambulatory conditions intra-arterial recordings are the only practical way to gain insight into the accuracy of noninvasive devices.¹⁸

	Reproducibility

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
The reproducibility of ambulatory blood pressure monitoring needs to be compared with that of conventional sphygmomanometry. The use of correlation coefficients for this purpose is misleading.²⁶ Bland and Altman²⁶ therefore proposed an alternative approach based on graphic techniques (Fig 1) and simple calculations, which provide information on the reproducibility of both group means and individual measurement results. A higher repeatability coefficient, that is, twice the standard deviation of the differences between duplicate measurements,²⁶ signifies lower within-subject reproducibility. For comparison of the reproducibility of various measurements, the repeatability coefficients can be expressed as a percentage of nearly maximal variation, that is, the interval encompassing four times the standard deviation of the averaged duplicate measurements.^{13 27 28}

View larger version (20K): [in this window] [in a new window]   Figure 1. Scatterplots show repeatability of diastolic pressure (DBP) measured on two occasions 1 month apart in patients taking a placebo. a, Clinic DBP: n=75; mean difference, 1.67 mm Hg; standard deviation of the difference, 12.3 mm Hg. b, Ambulatory DBP: n=75; mean difference, 0.94 mm Hg; standard deviation of the difference, 6.3 mm Hg. From Conway and Coats27 with permission.

Group means of the blood pressure level^{13 27 28} and of the parameters of the diurnal blood pressure profile¹³ can be accurately reproduced when intermittent noninvasive recordings are repeated in the same subjects. In addition, as far as the blood pressure level is concerned, ambulatory measurements are characterized by a greater within-subject reproducibility than conventional blood pressure readings.^{27 28} This can be explained by the absence of digit preference, observer bias, and the white coat effect^{16 29} but foremost by the greater number of readings averaged for calculation of the ambulatory blood pressure means.^{27 28}

The better within-subject reproducibility makes it possible to enroll fewer patients in crossover trials with ambulatory monitoring than with conventional sphygmomanometry, provided that the averages of at least 20 ambulatory readings are compared.^{27 28} However, in contrast to what is often perceived, the advantage of the better within-subject reproducibility of ambulatory measurements is lost when the blood pressure over a short time (for example, hourly averages) constitutes the focus of attention^{30 31} and/or when in trials with a parallel group design the between-subject rather than the within-subject variability is driving the statistical tests.³¹ For these reasons, trials involving the comparison of diurnal blood pressure profiles, for example, to determine the duration of action of antihypertensive agents, should recruit considerably more patients than the usual clinical trial.³¹

In contrast to the blood pressure level, the parameters of the diurnal blood pressure profile as determined by noninvasive ambulatory monitoring are poorly reproducible within subjects.¹³ This may be due to measurement error accumulated over the day but also to true biological variability and diurnal, seasonal, and random changes in the pattern of activity, which constitute an important, if not the overriding, determinant of the ambulatory pressure. Thus, studies based on a single ambulatory recording are insufficient for characterizing individuals with respect to their diurnal blood pressure profile, regardless of whether the profile has been analyzed by Fourier analysis³² or by other statistical techniques.³³ Increasing the number of recordings per subject or standardizing activity patterns during the recordings may increase the potential of 24-hour ambulatory monitoring to reproduce the diurnal blood pressure profile of individual subjects.

	Auscultatory Versus Oscillometric Techniques

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
Most of the blood pressure–measuring devices manufactured for use in ambulatory conditions or at home³⁴ use either an auscultatory or oscillometric method, or a combination of both techniques.^{35 36} The oscillometric compared with the auscultatory technique has the advantage of being less expensive from an engineering point of view and requiring less-complex algorithms. Oscillometry can be used in noisy surroundings and provides readings when an auscultatory gap is present; when the Korotkoff sounds persist until zero pressure, such as in patients with hyperkinetic circulation³⁷ ; or when the sounds are faint, such as in obese subjects. The position of the microphone(s) is a source of error specific to the auscultatory approach.³⁷ However, both methods of measurement are equally affected by dysrhythmias and artifacts of motion, although all devices do not perform in a like manner. The oscillometric SpaceLabs 90202 recorder, for instance, has been reported to produce error codes in 82% of its readings during dynamic bicycle exercise, whereas in similar conditions the relative number of error readings amounted to only 7% for both the Accutracker II (auscultatory with mandatory electrocardiographic gating; Suntech Medical Instruments) and Del Mar P-IV (auscultatory; Del Mar Avionics) and to 9% and 12% for the Colin ABPM 630 (Colin Medical Instruments) in oscillometric and auscultatory modes, respectively.¹⁹ A few devices measure pressure simultaneously by auscultation and oscillometry.^{19 38} They provide the means for comparison of the two techniques in similar conditions.³⁸ Standard auscultatory readings may be supplemented by oscillometric measurements whenever the former cannot be successfully completed, or vice versa.³⁸

Auscultation of the Korotkoff sounds remains the established standard technique for determination of blood pressure in clinical medicine. Dependable physiological principles underlie the determination of mean arterial pressure by oscillometry,³⁹ but a firm conceptual basis is still lacking for the determination of systolic and diastolic pressures by the latter approach. Some oscillometric devices record systolic pressure when the oscillations in the cuff suddenly increase in amplitude, mean pressure at maximal oscillation, and diastolic pressure when the amplitude of the oscillations abruptly falls off.

Most if not all manufacturers of monitoring devices refuse to disclose the proprietary algorithms for pressure measurement. Moreover, manufacturers tend to modify the devices and algorithms without prior notice.^{40 41 42} Especially for oscillometric devices, which put empirically derived algorithms into practice for the estimation of systolic and diastolic pressures, this practice is no longer acceptable. The original guidelines of the British Hypertension Society stated that when manufacturers incorporate modifications into externally identical or indistinguishable versions of a model this should be clearly indicated and that full details on how the new device differs from earlier versions should be provided.²⁴ The revision of the British guidelines stressed that it is incumbent upon manufacturers to clearly indicate all modifications made to the hardware and software components of automated devices, for instance, by changing the device number.²⁵ Furthermore, modified devices must be subject to a new validation.²⁵

	Validation Studies in Special Populations

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
The procedures required for the validation of ambulatory blood pressure monitors have been thoroughly standardized.^{24 25 43} Obviously, monitors used in clinical practice and research should have successfully passed these validation tests. However, when ambulatory blood pressure monitoring is to be used in special patient populations, such as older subjects or pregnant women,^{44 45 46} or in special conditions, such as exercise,^{19 21 47} a specific demonstration of accuracy in these defined subgroups and conditions is necessary.^{25 48}

The Elderly
Blood pressure rises with advancing age, which explains why hypertension is more prevalent among older people.⁴⁹ Blood pressure variability increases with advancing age and higher pressure.^{50 51} It is therefore unfortunate that ambulatory monitors seem to be less accurate in older subjects^{52 53 54} and hypertensive patients.^{52 54 55 56} Ambulatory monitoring is often used in older subjects, but unfortunately, few reports specifically addressing the validation of ambulatory monitors in the elderly⁵² are available in the literature.

Several investigators reported in population-based studies that the age-related increase in systolic pressure was less when the latter was measured by ambulatory monitoring instead of conventional sphygmomanometry.^{4 57 58 59} It is unlikely that these observations are due to only measurement artifact, because in these surveys^{4 57 58 59} various types of monitors have been used. Across studies, the relationship with age was also consistently weaker for ambulatory blood pressure, regardless of whether the reference pressure had been measured by classic sphygmomanometry,^{4 57 58} by a stationary automated device,⁵⁹ at home,^{4 58} or in special clinics.^{57 59}

Pregnant Women
In conditions characterized by a high cardiac output, such as anemia, thyrotoxicosis, or pregnancy, systolic pressure may be elevated and the Korotkoff sounds may be heard until the pressure in the cuff falls to zero.⁶⁰ Under these circumstances both phase IV and phase V should be recorded. Phase IV has been recommended for use in pregnant women,⁶⁰ although comparisons with intra-arterial pressure have not yet produced the evidence to substantiate the claim that the phase IV diastolic pressure is more accurate.⁶¹

The accuracy of the auscultatory A&D TM-2420 (A&D Engineering Co) was evaluated in pregnant women by comparing its measurements with those taken simultaneously by two trained observers using a random-zero sphygmomanometer. The mean differences (±SD) between the two observers were -0.2±2.5 mm Hg for systolic pressure, +1.2±2.5 mm Hg for phase IV diastolic pressure (P=.01), and +0.04±2.6 mm Hg for phase V diastolic pressure. The mean differences between the mercury standard (average of the readings by the two observers) and the monitor were -0.5±2.7 mm Hg for systolic pressure, -5.4±5.3 mm Hg for phase IV diastolic pressure (P<.001), and +0.9±3.7 mm Hg for phase V diastolic pressure. These findings demonstrated that compared with a mercury standard it is possible to obtain reliable measurements of systolic pressure and phase V diastolic pressure in pregnant women.⁴⁵

The SpaceLabs 90207 has also been validated in pregnant normotensive women. According to the protocol of the British Hypertension Society, it achieved an A mark for systolic pressure but only a C grading for diastolic pressure.⁴⁶ The mark attained for systolic pressure was one grade higher than in nonpregnant subjects,⁶² and the result for diastolic pressure was one grade lower. Phase IV diastolic pressure was used for determination of the mercury standard. As in the previous study⁴⁵ the agreement on phase IV diastolic pressure among the observers was low, suggesting that the lower accuracy with respect to diastolic pressure may be due to this phenomenon rather than to an inherent inaccuracy of the devices in a pregnant population.⁴⁶

	The Peñáz or Volume-Clamp Method

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
In 1969 Peñáz patented his so-called volume-clamp method,⁶³ and at least two groups^{64 65} subsequently developed practical instruments for measuring finger arterial pressure according to the volume-clamp method. Wesseling⁶⁵ greatly improved the technique and first constructed the Finapres (TNO Biomedical Instruments), a stationary device. The first prototype was a simple laboratory model that needed manual interaction to record blood pressure reliably. Presently, the Finapres is fully automated and contains expert systems monitoring the physiological changes in the arterial circulation in the finger.⁶⁵ From the stationary Finapres, the Portapres was developed for use in ambulatory conditions.⁶⁶ To measure blood pressure at the finger during prolonged periods without discomfort to the patient, the Portapres is equipped with two finger cuffs and a switching device that automatically alternates the measurement site every 30 minutes. Furthermore, during ambulation the hand moves freely with respect to the level of the heart. To correct for these hydrostatic effects,^{5 6} the Portapres incorporates a system that continuously determines the position of the finger relative to a reference pressure transducer at heart level.⁶⁶

Several studies using intra-arterial tracings as a reference reported on the accuracy of the volume-clamp method for measurement of pressure in digital arteries under stationary^{66 67 68 69 70 71} or ambulatory⁶⁶ conditions, during physiological^{66 67 72 73} or pharmacological⁶⁷ interventions in the laboratory, or during the induction of anesthesia.⁷⁴ The differences between the intra-arterial and noninvasive measurements, however, were obviously influenced by the change in the pressure wave, as the blood is propagated through the arterial vascular tree from the heart to the peripheral vessels. As a consequence of the age-related hemodynamic changes, systolic pressure is lower in the brachial than in the digital arteries in younger subjects, whereas in older people the opposite is observed.⁷⁵ Furthermore, the pressure gradient from the brachial to the digital arteries explains why mean and diastolic pressures are lower at the latter, more distal, site.⁷⁶

In general, the devices for measurement of arterial pressure in the digital arteries by the volume-clamp method are reasonably accurate and perform well in evaluating blood pressure changes over shorter time intervals. Nevertheless, they tend to slightly underestimate systolic, mean, and diastolic pressures at the level of the brachial artery^{66 67 68 69 70 71 72 73 74} (Fig 2). Two studies showed an unexpected overestimation of diastolic pressure by the Finapres.^{67 74} In one,⁷⁴ the Ohmeda Finapres TM was used and shown to measure significantly higher pressure than the Dutch-made models⁶⁸ ; also, the cuffs were applied to the thumb, for which they were originally not designed.⁶⁵ An overestimation of systolic pressure was reported for the Finapres in one study⁶⁷ and for the Ohmeda Finapres TM in another.⁶⁸

View larger version (23K): [in this window] [in a new window]   Figure 2. Graphs show point estimate and 95% confidence intervals of the differences between finger (FINAP) and intra-arterial (IAP) blood pressures in various studies. The devices tested are identified by model numbers: tno0 indicates TNO model 0; tno2, model 2; tno3, model 3; tno4, model 4; tno5, model 5; and ohm1, Ohmeda model 2300. N represents the number of normal awake subjects or anesthetized (anaes) patients included in each study. The site of arterial cannulation is indicated by B for brachial or R for radial. From Imholz et al68 with permission.

In conclusion, the finger arterial volume-clamp method makes continuous beat-to-beat recordings of blood pressure possible in a noninvasive manner and under a variety of conditions. It also provides the means for evaluation of blood pressure and heart rate variability.^{77 78} On balance, the available literature^{66 67 68 69 70 71 72 73 74} suggests that finger plethysmography enables one to record blood pressure level with an accuracy that is imperfect but under ideal conditions comparable to that of the noninvasive intermittent technique.

	Blood Pressure Monitoring as a Tool for Evaluation of Arteries

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
Several studies have suggested that ambulatory compared with conventionally measured blood pressure correlates more closely with several indexes of target-organ damage, such as echocardiographic signs of left ventricular hypertrophy.^{79 80} Using three different approaches, Asmar et al^{81 82 83} recently showed that ambulatory monitoring also provided a sensitive approach for evaluating the relationship between dysfunction of the arterial wall and blood pressure. Along these lines, one of the future perspectives of ambulatory monitoring possibly consists of the indirect evaluation of arterial distensibility by ambulatory blood pressure monitoring. Indeed, the time lag between the onset of the QRS complex and the Korotkoff sounds signifying diastolic pressure, that is, the so-called QKD interval, is determined by the velocity of the pulse wave across the arterial tree and is therefore regarded to reflect arterial distensibility.^{84 85}

Reference values for the QKD interval have recently been proposed.⁸⁵ Moreover, Gosse et al⁸⁴ found that as expected under the above hypothesis^{84 85} the QKD interval was reduced with advancing age and in the presence of hypertension. Although the possibility of noninvasively monitoring arterial distensibility in ambulatory conditions undoubtedly constitutes an attractive prospect, the QKD technique is still being debated and awaits further validation by other groups.

	Conclusions

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
Ambulatory blood pressure monitoring by noninvasive intermittent techniques is widely used despite artifacts due to cuff size, movement, body position, short-term blood pressure variability, and interference with sleep. However, the performance of portable monitors in truly ambulatory conditions and during exercise remains a matter of controversy, as well as the procedures required for the validation of devices under these circumstances. On the other hand, there is general agreement that whenever a monitor is going to be used in special populations, such as older subjects or pregnant women, or in special conditions, such as exercise, a specific demonstration of its accuracy in these defined subgroups and conditions is warranted.

Whether an auscultatory or oscillometric technique is preferred remains debatable, because both techniques have specific advantages and disadvantages and both can provide accurate results under a variety of operating conditions. Their combination in a single device, however, may be useful for attaining a higher percentage of successfully completed readings and enabling the informative comparison between simultaneous pressure readings by two different methods. The opinion strongly prevails that manufacturers should disclose the algorithms of their devices, especially if these programs are not directly based on physiological principles but are empirically determined. This would give researchers involved in validation, as well as scientific and clinical users, a better insight on what can be expected with respect to performance in particular patient populations and under specific operating conditions. Moreover, manufacturers should specify all changes made to the hardware and software of a previously validated monitor.

	Acknowledgments

 
The experts taking part in The Fourth International Consensus Meeting on 24-Hour Ambulatory Blood Pressure Monitoring were as follows (an asterisk marks the names of the attendants whose comments were taken into account and who expressed their approval of this review): Antoon Amery,* Hilde Celis,* Robert Fagard,* Jan A. Staessen,* Lutgarde Thijs,* and Roger Van Hoof* (Leuven, Belgium); Roland Asmar* (Paris, France); Frank Buntinx* and Paul De Cort* (Leuven, Belgium); Denis Clement* and Daniel Duprez* (Ghent, Belgium); Andrew J.S. Coats* (London, UK); James Conway* (Oxford, UK); Jean-Paul Degaute* and Jean-François De Plaen* (Brussels, Belgium); Peter W. de Leeuw* (Maastricht, Netherlands); Richard B. Devereux and Thomas G. Pickering* (New York, NY); Aris D. Efstratopoulos* (Athens, Greece); Henry L. Elliott* (Glasgow, UK); Jürgen Gellert* (Wuppertal, Germany); Philippe Gosse* (Bordeaux, France); Yutaka Imai* (Sendai, Japan); Ben P.M. Imholz,* Gert A. van Montfrans, and Karel H. Wesseling* (Amsterdam, Netherlands); Chris Kingswood* (Brighton, UK); Lisheng Liu* (Beijing, People's Republic of China); Jean-Michel Mallion* (Grenoble, France); Eoin T. O'Brien* (Dublin, Ireland); Joan Ocón-Pujadas* (Barcelona, Spain); Kuniaki Otsuka* (Tokyo, Japan); Paolo Palatini* (Padova, Italy); Gianfranco Parati* (Milano, Italy); Dorothee Perloff* (San Francisco, Calif); Carlo Porcellati and Paolo Verdecchia* (Perugia, Italy); Edward B. Raftery* (Harrow, Middlesex, UK); Josep Redon* (Valencia, Spain); Joseph Rosenfeld* (Tel Aviv, Israel); Andrzej Rynkiewicz* (Gdansk, Poland); Antonio Salvetti* (Pisa, Italy); Jaakko Tuomilheto* and Hannu Vanhanen* (Helsinki, Finland); Bernard Waeber* (Lausanne, Switzerland); William B. White* (Farmington, Conn); and John Webster* (Aberdeen, UK). The organization of The Fourth International Consensus Meeting on 24-Hour Blood Pressure Monitoring was made possible thanks to support from Cassella AG (Frankfurt, Germany), Pfizer NV (Brussels, Belgium), and Zeneca NV (Destelbergen, Belgium). Additional grants were provided by Roche NV (Brussels, Belgium), Servier Benelux (Brussels, Belgium), and SpaceLabs Inc (Redmond, Wash). The secretarial assistance of Ida Tassens is gratefully acknowledged.

	Footnotes

 
¹ Died on November 2, 1994.

Received November 16, 1994; first decision January 13, 1995; accepted August 25, 1995.

	References

Top Abstract Introduction Cuff Size Position of the Arm Short-term Blood Pressure... Disturbance of Sleep Performance During Ambulatory... Reproducibility Auscultatory Versus... Validation Studies in Special... The Peñáz or... Blood Pressure Monitoring as... Conclusions References

 
1. van Montfrans GA, Van Der Hoeven GMA, Karemaker JM, Wieling W, Dunning AJ. Accuracy of auscultatory blood pressure measurement with a long cuff. Br Med J. 1987;295:354-355.

2. Guidelines Sub-Committee. 1993 guidelines for the management of mild hypertension: memorandum from a World Health Organization/International Society of Hypertension meeting. J Hypertens. 1993;11:905-918. [Medline] [Order article via Infotrieve]

3. The Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. The Fifth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC V). Arch Intern Med. 1993;153:154-183. [Abstract/Free Full Text]

4. Staessen JA, Fagard R, Lijnen P, Thijs L, Van Hulle S, Vyncke G, Amery A. Ambulatory blood pressure and blood pressure measured at home: progress report on a population study. J Cardiovasc Pharmacol. 1994;23(suppl 5):S5-S11.

5. Mitchell PL, Parlin RW, Blackburn H. Effect of vertical displacement of the arm on indirect blood-pressure measurement. N Engl J Med. 1964;271:72-74.

6. Schwan A, Pavek K. Change in posture during sleep causes errors in non-invasive automatic blood pressure recordings. J Hypertens. 1989;7(suppl 6):S62-S63.

7. Di Rienzo M, Grassi G, Pedotti A, Mancia G. Continuous vs intermittent blood pressure measurements in estimating 24-hour average blood pressure. Hypertension. 1983;5:264-269. [Abstract/Free Full Text]

8. Parati G, Mutti E, Ravogli A, Trazzi S, Villani A, Mancia G. Advantages and disadvantages of non-invasive ambulatory blood pressure monitoring. J Hypertens. 1990;8(suppl 6):S33-S38.

9. Bos WJW, van Goudoever J, van Montfrans GA, Wesseling KH. Influence of short-term blood pressure variability on blood pressure determinations. Hypertension. 1992;19:606-609. [Abstract/Free Full Text]

10. Degaute JP, van de Borne P, Kerkhofs M, Dramaix M, Linkowski P. Does non-invasive ambulatory blood pressure monitoring disturb sleep? J Hypertens. 1992;10:879-885. [Medline] [Order article via Infotrieve]

11. Degaute JP, van de Borne P, Linkowski P, Van Cauter E. Quantitative analysis of the 24-hour blood pressure and heart rate patterns in young men. Hypertension. 1991;18:199-210. [Abstract/Free Full Text]

12. Davies RJO, Jenkins NE, Strading JR. Effects of measuring ambulatory blood pressure on sleep and on blood pressure during sleep. Br Med J. 1994;308:820-823. [Abstract/Free Full Text]

13. Staessen J, Bulpitt CJ, O'Brien E, Cox J, Fagard R, Stanton A, Thijs L, Van Hulle S, Vyncke G, Amery A. The diurnal blood pressure profile: a population study. Am J Hypertens. 1992;5:386-392. [Medline] [Order article via Infotrieve]

14. Prinze PN, Vitiello MV, Raskind MA, Thorpy MJ. Geriatrics: sleep disorders and aging. N Engl J Med. 1990;323:520-525. [Medline] [Order article via Infotrieve]

15. Veerman DP, van Montfrans GA, Wieling W. Effects of cuff inflation on self-recorded blood pressure. Lancet. 1990;335:451-453. [Medline] [Order article via Infotrieve]

16. Parati G, Pomidossi G, Casadei B, Mancia G. Lack of alerting reactions to intermittent cuff inflations during noninvasive blood pressure monitoring. Hypertension. 1985;7:597-601. [Abstract/Free Full Text]

17. Kugler J, Schmitz N, Seelbach H, Rollnik J, Krüskemper GM. Rise in systolic blood pressure during sphygmomanometry depends on the maximum inflation pressure of the arm cuff. J Hypertens. 1994;12:825-829. [Medline] [Order article via Infotrieve]

18. Mancia G, Parati G. Commentary on the revised British Hypertension Society protocol for evaluation of blood pressure measuring devices: a critique of aspects related to 24-hour ambulatory blood pressure measurement. J Hypertens. 1993;11:595-597. [Medline] [Order article via Infotrieve]

19. White WB, Lund-Johansen P, Omvik P. Assessment of four ambulatory blood pressure monitors and measurements by clinicians versus intraarterial blood pressure at rest and during exercise. Am J Cardiol. 1990;65:60-66. [Medline] [Order article via Infotrieve]

20. White WB, Lund-Johansen P, McCabe EJ, Omvik P. Clinical evaluation of the Accutracker II ambulatory blood pressure monitor: assessment of performance in two countries and comparison with sphygmomanometry and intra-arterial blood pressure at rest and during exercise. J Hypertens. 1989;7:967-975. [Medline] [Order article via Infotrieve]

21. Gould BA, Hornung RS, Altman DG, Cashman PMM, Raftery EB. Indirect measurement of blood pressure during exercise testing can be misleading. Br Heart J. 1985;53:611-615. [Abstract/Free Full Text]

22. Meyer-Sabellek W, Schulte KL, Distler A, Gotzen R. Methodological developments and problems of recorders for automatic, indirect, ambulatory 24-hour monitoring of blood pressure. In: Meyer-Sabellek W, Anlauf M, Gotzen R, Steinfeld L, eds. Blood Pressure Measurements. Darmstadt, Germany: Steinkopff Verlag; 1989:127-140.

23. Blank SG, West JE, Müller FB, Cody RJ, Harshfield GA, Pecker MS, Laragh JH, Pickering TG. Wideband external pulse recording during cuff deflation: a new technique for evaluation of the arterial pressure pulse and measurement of blood pressure. Circulation. 1988;77:1297-1305. [Abstract/Free Full Text]

24. O'Brien E, Petrie J, Littler W, de Swiet M, Padfield PL, O'Malley K, Jamieson, Altman D, Bland M, Atkins N. The British Hypertension Society protocol for the evaluation of automated and semi-automated blood pressure measuring devices with special reference to ambulatory systems. J Hypertens. 1990;8:607-619. [Medline] [Order article via Infotrieve]

25. O'Brien E, Petrie J, Littler W, de Swiet M, Padfield PL, Altman DG, Bland M, Coats A, Atkins N. Short report: an outline of the revised British Hypertension Society protocol for the evaluation of blood pressure measuring devices. J Hypertens. 1993;11:677-679. [Medline] [Order article via Infotrieve]

26. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986;2:307-310.

27. Conway J, Coats A. Value of ambulatory blood pressure monitoring in clinical pharmacology. J Hypertens. 1989;7(suppl 3):S29-S32.

28. Conway J, Johnston J, Coats A, Somers V, Sleight P. The use of ambulatory blood pressure monitoring to improve the accuracy and to reduce the number of subjects in clinical trials of antihypertensive agents. J Hypertens. 1988;6:111-116. [Medline] [Order article via Infotrieve]

29. Pickering TG, James GD, Boddie C, Harshfield GA, Blank S, Laragh JH. How common is white coat hypertension? JAMA. 1988;259:225-228. [Abstract/Free Full Text]

30. Mancia G, Omboni S, Parati G, Trazzi S, Mutti E. Limited reproducibility of hourly blood pressure values obtained by ambulatory blood pressure monitoring: implications for studies on antihypertensive drugs. J Hypertens. 1992;10:1531-1535. [Medline] [Order article via Infotrieve]

31. Staessen JA, Thijs L, Mancia G, Parati G, O'Brien ET, on behalf of the Syst-Eur Investigators. Clinical trials with ambulatory blood pressure monitoring: fewer patients needed? Lancet. 1994;344:1552-1556. [Medline] [Order article via Infotrieve]

32. Thijs L, Staessen J, Fagard R. Analysis of the diurnal blood pressure curve. High Blood Press. 1992;1:17-28.

33. Stanton A, Cox J, Atkins N, O'Malley K, O'Brien E. Cumulative sums in quantifying circadian blood pressure patterns. Hypertension. 1992;19:93-101. [Abstract/Free Full Text]

34. Imai Y, Satoh H, Nagai K, Sakuma M, Sakuma H, Minami N, Munakata M, Hashimoto J, Yamagishi T, Watanabe N, Yabe T, Nishiyama A, Nakatsuka H, Koyama H, Abe K. Characteristics of a community-based distribution of home blood pressure in Ohasama in northern Japan. J Hypertens. 1993;11:1441-1449. [Medline] [Order article via Infotrieve]

35. Clement DL. Ambulatory blood pressure recordings: quo vadis? Neth J Med. 1992;40:165-171. [Medline] [Order article via Infotrieve]

36. Meyer-Sabellek W, Schulte KL, Gotzen R. Technical possibilities and limits of indirect automatic twenty-four-hour blood pressure devices. J Hypertens. 1989;7(suppl 3):S21-S24.

37. Palatini P, Penzo M, Canali C, Pessina AC. Validation of the A & D TM-2420 Model 7 for ambulatory blood pressure monitoring and effect of microphone replacement on its performance. J Ambul Monit. 1991;4:281-288.

38. Imai Y, Sasaki S, Minami N, Munakata M, Hashimoto J, Sakuma H, Sakuma M, Watanabe N, Imai K, Sekino H, Abe K. The accuracy and performance of the A&D TM 2421, a new ambulatory blood pressure monitoring device based on the cuff-oscillometric method and the Korotkoff sound technique. Am J Hypertens. 1992;5:719-726. [Medline] [Order article via Infotrieve]

39. Ramsey M. Noninvasive automatic determination of mean arterial pressure. Med Biol Eng Comput. 1979;17:11-18. [Medline] [Order article via Infotrieve]

40. Hansen KW, Orskov H. A plea for consistent reliability in ambulatory blood pressure monitors: a reminder. J Hypertens. 1992;10:1313-1315. [Medline] [Order article via Infotrieve]

41. O'Brien E, Mee F, Atkins N, O'Malley K. Accuracy of the Takeda TM-2420/TM-2020 determined by the British Hypertension Society Protocol. J Hypertens. 1991;9(suppl 5):S17-S23.

42. O'Brien E, O'Malley K, Atkins N, Mee F. A review of validation procedures for blood pressure measuring devices. In: Waeber B, O'Brien E, O'Malley K, Brunner HR, eds. Twenty-Four-Hour Blood Pressure Monitoring in Clinical Practice. New York, NY: Raven Press Publishers; 1994:1-32.

43. White WB, Berson AS, Robbins C, Jamieson MJ, Prisant ML, Roccella E, Sheps SG. National standard for measurement of resting and ambulatory blood pressures with automated sphygmomanometers. Hypertension. 1993;21:504-509. [Abstract/Free Full Text]

44. Halligan A, O'Brien E, O'Malley K, Mee F, Atkins N, Conroy R, Walshe JJ, Darling M. Twenty-four-hour ambulatory blood pressure measurement in a primigravid population. J Hypertens. 1993;11:869-873. [Medline] [Order article via Infotrieve]

45. Clark S, Hofmeyr GJ, Coats AJS, Redman CWG. Ambulatory blood pressure monitoring during pregnancy: validation of the TM-2420 monitor. Obstet Gynecol. 1991;77:152-155. [Medline] [Order article via Infotrieve]

46. O'Brien E, Mee F, Atkins N, Halligan A, O'Malley K. Accuracy of the SpaceLabs 90207 blood pressure measuring system in normotensive pregnant women determined by the British Hypertension Society Protocol. J Hypertens. 1993;11(suppl 5):282-283.

47. Henschel A, De La Vega F, Taylor HL. Simultaneous direct and indirect blood pressure measurements in man at rest and work. J Appl Physiol. 1954;5:506-508.

48. Coats AJS, Clark SJ. Validation of ambulatory monitors in special populations. Am J Hypertens. 1992;5:664-669. [Medline] [Order article via Infotrieve]

49. Staessen J, Amery A, Fagard R. Editorial review. Isolated systolic hypertension. J Hypertens. 1990;8:393-405. [Medline] [Order article via Infotrieve]

50. Mancia G, Di Rienzo M, Parati G. Ambulatory blood pressure monitoring use in hypertension research and clinical practice. Hypertension. 1993;21:510-524. [Free Full Text]

51. Veerman DP, Imholz BPM, Wieling W, Karemaker JM, van Montfrans GA. Effects of aging on blood pressure variability in resting conditions. Hypertension. 1994;24:120-130. [Abstract/Free Full Text]

52. Miller ST, Elam JT, Graney MJ, Applegate WB. Discrepancies in recording systolic blood pressure of elderly persons by ambulatory blood pressure monitor. Am J Hypertens. 1992;5:16-21. [Medline] [Order article via Infotrieve]

53. O'Brien E, Mee F, Atkins N, O'Malley K. Technical aspects of ambulatory blood pressure monitoring in the elderly. Cardiol Elderly. 1993;1:464-469.

54. Cates EM, Schlussel YR, James GD, Pickering TG. A validation study of the SpaceLabs 90207 ambulatory blood pressure monitor. J Ambul Monit. 1990;3:149-154.

55. O'Brien E, Atkins N, Mee F, O'Malley K. Comparative accuracy of six ambulatory devices according to blood pressure levels. J Hypertens. 1993;11:673-675. [Medline] [Order article via Infotrieve]

56. Pannarale G, Bebb G, Clark S, Sullivan A, Foster C, Coats AJS. Bias and variability in blood pressure measurement with ambulatory recorders. Hypertension. 1993;22:591-598. [Abstract/Free Full Text]

57. O'Brien ET, Murphy J, Tyndall A, Atkins N, Mee F, McCarthy G, Staessen J, Cox J, O'Malley K. Twenty-four-hour ambulatory blood pressure in men and women aged 17 to 80 years: the Allied Irish Bank Study. J Hypertens. 1991;9:355-360. [Medline] [Order article via Infotrieve]

58. Staessen J, O'Brien E, Atkins N, Bulpitt CJ, Cox J, Fagard R, O'Malley K, Thijs L, Amery A. The increase in blood pressure with age and body mass index is overestimated by conventional sphygmomanometry. Am J Epidemiol. 1992;136:450-459. [Abstract/Free Full Text]

59. Imai Y, Nagai K, Sakuma M, Sakuma H, Nakatsuka H, Satoh H, Minami N, Munakata M, Hashimoto J, Yamagishi T, Watanabe N, Yabe T, Nishiyama A, Abe K. Ambulatory blood pressure of adults in Ohasama, Japan. Hypertension. 1993;22:900-912. [Abstract/Free Full Text]

60. Frohlich ED, Grim C, Labarthe DR, Maxwell MH, Perloff D, Weidman WH. Recommendations for human blood pressure determination by sphygmomanometers: report of a special task force appointed by the Steering Committee, American Heart Association. Hypertension. 1988;11:210A-222A.

61. Ginsburg J, Duncan S. Direct and indirect blood pressure measurements in pregnancy. J Obstet Gynaecol Br Commonw. 1969;76:705-710. [Medline] [Order article via Infotrieve]

62. O'Brien E, Mee F, Atkins N, O'Malley K. Accuracy of the SpaceLabs 90207 determined by the British Hypertension Society Protocol. J Hypertens. 1991;9:573-574. [Medline] [Order article via Infotrieve]

63. Peñáz J. Patentova Listina. CISLO 133205, 1969.

64. Yamakoshi K, Komiya A, Shimazu H, Ito H, Togawa T. Noninvasive automatic monitoring of instantaneous arterial blood pressure using the vascular unloading technique. Med Biol Eng Comput. 1983;21:557-565. [Medline] [Order article via Infotrieve]

65. Wesseling KH. Finapres, continuous noninvasive finger arterial pressure based on the method of Peñáz. In: Meyer-Sabellek W, Anlauf M, Gotzen R, Steinfeld L, eds. Blood Pressure Measurements: New Techniques in Automatic and 24-Hour Indirect Monitoring. Darmstadt, Germany: Steinkopff Verlag; 1989:161-172.

66. Imholz BPM, Langewouters GJ, van Montfrans GA, Parati G, van Goudoever J, Wesseling KH, Wieling W, Mancia G. Feasibility of ambulatory, continuous 24-hour finger arterial pressure recording. Hypertension. 1993;21:65-73. [Abstract/Free Full Text]

67. Parati G, Casadei R, Groppelli A, Di Rienzo M, Mancia G. Comparison of finger and intra-arterial blood pressure monitoring at rest and during laboratory testing. Hypertension. 1989;13:647-655. [Abstract/Free Full Text]

68. Imholz BPM, Wieling W, Langewouters GJ, van Montfrans GA. Continuous finger arterial pressure: utility in the cardiovascular laboratory. Clin Auton Res. 1991;1:45-53.

69. Van Egmond J, Hasenbos M, Crul JF. Invasive versus noninvasive measurement of arterial pressure. Br J Anaesthesiol. 1984;57:434-444. [Abstract/Free Full Text]

70. Smith NT, Wesseling KH, de Wit B. Evaluation of two prototype devices producing noninvasive, pulsatile, calibrated blood pressure measurement from a finger. J Clin Monit. 1985;1:17-29. [Medline] [Order article via Infotrieve]

71. Molhoek GP, Wesseling KH, Settels JJM, van Vollenhoven E, Weeda HWH, de Wit B, Arntzenius AC. Evaluation of the Peñáz servo-plethysmomanometer for the continuous non-invasive measurement of finger blood pressure. Basic Res Cardiol. 1984;79:598-609. [Medline] [Order article via Infotrieve]

72. Imholz BPM, van Montfrans GA, Settels JJ, Van Der Hoeven GMA, Karemaker JM, Wieling WW. Continuous non-invasive blood pressure monitoring: reliability of Finapres device during the Valsalva manoeuvre. Cardiovasc Res. 1988;22:390-397. [Medline] [Order article via Infotrieve]

73. Imholz BPM, Settels JJ, van den Meiracker AH, Wesseling KH, Wieling W. Noninvasive continuous finger blood pressure measurement during orthostatic stress compared to intra-arterial pressure. Cardiovasc Res. 1990;24:214-221. [Abstract/Free Full Text]

74. Kermode JL, Davis NJ, Thompson WR. Comparison of the Finapres blood pressure monitor with intraarterial manometry during induction of anaesthesia. Anaesth Intensive Care. 1989;17:470-486. [Medline] [Order article via Infotrieve]

75. O'Rourke M. Arterial haemodynamics and ventricular-vascular interaction in hypertension. Blood Press. 1994;3:33-37.[Medline] [Order article via Infotrieve]

76. Rowell LB, Brengelmann GL, Blackmon JR, Bruce RA, Murray JA. Disparities between aortic and peripheral pulse pressures induced by upright exercise and vasomotor changes in man. Circulation. 1968;27:954-964.

77. Malliani A, Pagani M, Lombardi F, Furlan R, Guzzetti S, Cerutti S. Spectral analysis to assess increased sympathetic tone in arterial hypertension. Hypertension. 1991;17(suppl III):III-36-III-42.

78. Pagani M, Lombardi F, Guzzetti S, Rimoldi O, Furlan R, Pizzinelli P, Sandrone G, Malfatto G, Dell'Orto S, Piccaluga E, Turiel M, Baselli G, Cerutti S, Malliani A. Power spectral analysis of heart rate and arterial pressure variabilities as a marker of sympatho-vagal interaction in man and conscious dogs. Circ Res. 1986;59:178-193. [Abstract/Free Full Text]

79. Perloff D, Sokolow M, Cowan RM, Juster RP. Prognostic value of ambulatory blood pressure measurements: further analyses. J Hypertens. 1989;7(suppl 3):S3-S10.

80. Verdecchia P, Schillaci G, Boldrini F, Guerrieri M, Gatteschi C, Benemio G, Porcellati C. Risk stratification of left ventricular hypertrophy in systemic hypertension using noninvasive ambulatory blood pressure monitoring. Am J Cardiol. 1990;66:583-590. [Medline] [Order article via Infotrieve]

81. Asmar RG, Girerd XJ, Brahimi M, Safavian A, Safar ME. Ambulatory blood pressure measurement, smoking and abnormalities of glucose and lipid metabolism in essential hypertension. J Hypertens. 1992;10:181-187. [Medline] [Order article via Infotrieve]

82. Asmar RG, Brunel PC, Pannier BM, Lacolley PJ, Safar ME. Arterial distensibility and ambulatory blood pressure monitoring in essential hypertension. Am J Cardiol. 1988;61:1066-1070. [Medline] [Order article via Infotrieve]

83. Asmar R, Julia PL, Mascarel VL, Fabiani JN, Benetos A, Safar ME. Ambulatory blood pressure profile after carotid endarterectomy in patients with ischaemic arterial disease. J Hypertens. 1994;12:697-702. [Medline] [Order article via Infotrieve]

84. Gosse P, Guillo P, Ascher G, Clementy J. Assessment of arterial distensibility by monitoring the timing of Korotkoff sounds. Am J Hypertens. 1994;7:228-233. [Medline] [Order article via Infotrieve]

85. Gosse P, Cailleau C, Barthelemy JC, Chevalier JM, Clementy J. Mesure ambulatoire du temps d'apparition des bruits de Korotkoff (intervalle QKD) dans une population normale. Arch Mal Coeur. 1994;87:1083-1086.

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