[Dynamic monitoring of arterial pressure in the diagnosis of hypertension: problems and perspectives].
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Blood Pressure Determination↗
Biomedical subjects
G Parati
Publications and source records attributed to G Parati.
Advantages and disadvantages of non-invasive ambulatory blood pressure monitoring.
Our studies have shown that (1) automatic blood pressure readings obtained from portable monitors do not induce any alerting reaction or pressor response in the patient; (2) although the measurements are intermittent, non-invasive ambulatory blood pressure monitoring is able to provide a true estimate of 24-h blood pressure and heart rate mean values (the assessment of 24-h blood pressure and heart rate variabilities is less accurate); (3) the nocturnal fall in blood pressure is not altered by the possible disturbance to the patient's sleep induced by repeated cuff inflations; and (4) even when the automatic blood pressure readings obtained are similar to simultaneous readings obtained by a sphygmomanometer, the accuracy of the values provided by portable monitors used in truly ambulatory conditions cannot be taken for granted. These findings have particular implications for the cost: benefit ratio if ambulatory blood pressure monitoring is to be used in the routine evaluation of hypertensive patients.
Blood Pressure↗
Ambulatory blood pressure monitoring in the evaluation of antihypertensive treatment.
Cuff blood pressure measurements by doctors and self blood pressure measurements by patients reflect imprecisely 24-hour or daytime mean blood pressure values. This limits the physician's ability to diagnose the absence or presence of hypertension. It also limits his ability to evaluate the response to non-pharmacologic interventions or antihypertensive drugs. This is a major disadvantage because the prognosis of hypertensive persons depends to a large extent on the blood pressure attained during treatment. Ambulatory blood pressure monitoring is a valid method for assessing the effectiveness of antihypertensive treatment because it allows the physician: (1) to determine whether the initially elevated blood pressure is reduced under the various circumstances of the patient's lifetime; and (2) to exclude that this reduction is associated with hypotensive events that might interfere with organ nutrition and function during the day and night. However, this approach has a cost that makes its use impractical in clinical practice, except in cases in which there are reasons to suspect very low or excessively high blood pressures in conditions that are out of the reach of sphygmomanometry. Furthermore, the prognostic value of on-treatment ambulatory blood pressures is still unknown. On the other hand, studies on new antihypertensive agents derive great benefits from the use of ambulatory blood pressure monitoring. This is emphasized by the fact that the ambulatory blood pressure values are more reproducible than isolated cuff blood pressure values, allowing the number of patients necessary to establish an antihypertensive effect to be reduced. Furthermore, these values are little affected by placebo influences thus permitting simplification of the study design. Finally, sequential analysis of the data obtained provides accurate information on the duration of the antihypertensive effect, and thus on the optimal posology to be adopted. However, ambulatory blood pressure monitoring does have technical problems. In the case of non-invasive monitoring, the ability to measure blood pressure phasic events and variability is limited. Another problem, which is of greater importance, is that non-invasive blood pressure monitoring devices generate a number of artifactual and imprecise readings. These problems cannot be entirely eliminated by editing the blood pressure tracing.
Ambulatory Care↗
Early twenty-four-hour blood pressure elevation in subjects with parental hypertension.
We studied 15 normotensive offspring of hypertensive parents, comparing them with 15 normotensive controls matched for sex, body mass index and age. In the offspring, both parents were hypertensive, while in the controls, neither parent was hypertensive. Blood pressure was measured at rest, during a variety of laboratory stressors (mental arithmetic, mirror drawing test, hand grip and cold pressor test), and was also monitored for 24 h in ambulatory conditions (Spacelabs 5300 M, Richmond, Washington, USA). Resting mean and diastolic blood pressures were higher (P less than 0.05) in the subjects with parental hypertension than in those without. The mean blood pressure rise induced by the laboratory stressors was not significantly greater at any time in the subjects with hypertensive parents compared with controls. Twenty-four-hour systolic and mean blood pressures, however, were significantly higher (P less than 0.05) in the subjects with hypertensive parents than in the controls. Thus the higher office blood pressure shown in the prehypertensive stage by subjects with parental hypertension is not due to hypersensitivity to stress, but represents an early and permanent blood pressure elevation.
Adult↗
24 h sequential spectral analysis of arterial blood pressure and pulse interval in free-moving subjects.
A procedure for the 24 h tracking of the 0.25, 0.1, and 0.05 Hz oscillations in blood pressure (BP) and pulse interval (PI) in ambulant subjects has been developed. It includes: 1) sampling of a 24 h intra-arterial BP recording, extraction of the systolic (S) and diastolic (D) BP and PI from each heart beat followed by storage into separate series; 2) high-pass filtering and a splitting of each series into consecutive records of 256 values; 3) estimation of power spectral density (PSD) via FFT in each stationary record, and finally, computation of the power of each target oscillation. Using this procedure we analyzed data from ten hospitalized free-moving subjects in whom BP was recorded by the Oxford technique. The results revealed different patterns of the 0.25, 0.1, and 0.05 oscillations over the day-night cycle, showing a differentiated involvement during the 24 h of the mechanisms responsible for such rhythmic phenomena. Moreover, in order to reinforce the meaning of the obtained results and to exclude the possible negative effects due to the drawbacks typical of the FFT algorithm, we also performed a second spectral estimate based on the AR modeling. The obtained results validates the FFT approach.
Blood Pressure Determination↗
Comparison of finger and intra-arterial blood pressure monitoring at rest and during laboratory testing.
The accuracy of blood pressure values obtained by continuous noninvasive finger blood pressure recording via the FINAPRES device was evaluated by comparison with simultaneous intraarterial monitoring both at rest and during performance of tests known to induce fast and often marked changes in blood pressure. The comparison was performed in 24 normotensive or essential hypertensive subjects. The average discrepancy between finger and intra-arterial blood pressure recorded over a 30-minute rest period was 6.5 +/- 2.6 mm Hg and 5.4 +/- 2.9 mm Hg for systolic and diastolic blood pressure, respectively; a close between-method correspondence was also demonstrated by linear regression analysis. The beat-to-beat changes in finger systolic and diastolic blood pressure were on average similar to those measured intra-arterially during tests that induced a pressor or depressor response (hand-grip, cold pressor test, diving test, Valsalva maneuver, intravenous injections of phenylephrine and trinitroglycerine) as well as during tests that caused vasomotor changes without major variations in blood pressure (application of lower body negative pressure, passive leg raising). The average between-method discrepancy in the evaluation of blood pressure changes was never greater than 4.3 and 2.0 mm Hg for systolic and diastolic blood pressure, respectively; the corresponding standard deviations ranged between 4.6 and 1.6 mm Hg. Beat-to-beat computer analysis of blood pressure variability over the 30-minute rest period provided standard deviations almost identical when calculated by separate consideration of intra-arterial and finger blood pressure tracings (3.7 and 3.8 mm Hg, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Clinical and hemodynamic effects of celiprolol in essential hypertension.
The antihypertensive effect of celiprolol, a selective beta-adrenoceptor blocker with ancillary partial beta 2-agonist, vasodilator, and bronchosparing properties, has been evaluated in open and placebo-controlled trials. Celiprolol (200-600 mg once daily) has been reported to reduce blood pressure significantly in 60-80% of patients with side effects which are mild and low in frequency. The antihypertensive efficacy of celiprolol has been found comparable with that of propranolol, atenolol, metoprolol and nadolol, but celiprolol does not cause the same degree of bradycardia as these other drugs. By means of ambulatory blood pressure monitoring we have demonstrated that celiprolol, administered to 10 essential hypertensive patients (aged 20-64 years) as a single daily dose (200-400 mg), can induce a significant and sustained reduction in 24-h systolic and diastolic blood pressure, with no effects on 24-h heart rate. Similar results have been obtained in elderly patients (aged 65-74 years) responsive to this drug. Both in young and elderly patients treatment was well tolerated. Available evidence therefore suggests that celiprolol is an effective and safe antihypertensive drug, the favorable ancillary properties of which are likely to make its administration feasible in a broad range of patients.
Adrenergic beta-Antagonists↗
Balanced 24-hour blood pressure control by angiotensin-converting enzyme inhibitors administered once daily.
Traditional sphygmomanometric measurements may inaccurately reflect the actual blood pressure level over a 24-h period. This is due to several factors which are known to affect cuff blood pressure readings, including the limited number of readings obtainable throughout the 24 h and the alerting reaction and pressor response induced in patients by the presence of the physician. Twenty-four-hour ambulatory blood pressure monitoring has been reported to be superior to isolated cuff blood pressure readings in the diagnostic evaluation of hypertension and in assessing the blood pressure response to treatment. It does not trigger any emotionally induced pressor reaction and is able to provide a dynamic evaluation of blood pressure profiles over 24 h. The latter feature is particularly important in assessing the ability of once-daily antihypertensive treatment to reduce and maintain blood pressure at an appropriate level throughout the 24-h period. Studies to date using ambulatory blood pressure monitoring techniques suggest that once-daily administration of certain ACE inhibitors is capable of providing this long-term control of blood pressure. The 24-h antihypertensive action exerted by once-daily administration of ACE inhibitors is characterized by balanced blood pressure control throughout the day and night, and treatment does not appear to alter the neural mechanisms responsible for cardiovascular homeostasis, as suggested by the fact that these drugs have been shown not to affect 24-h blood pressure and heart rate variability. Furthermore, during administration of ACE inhibitors the sensitivity of arterial baroreceptor control of circulation is unaltered or even enhanced. These observations emphasise the potential importance of long-acting ACE inhibitors in the control of arterial hypertension.
Ambulatory Care↗
Evaluation of the antihypertensive effect of celiprolol by ambulatory blood pressure monitoring.
The use of ambulatory blood pressure monitoring has gained popularity because it is not subject to those limitations associated with traditional sphygmomanometry (inaccuracy of blood pressure readings, low number of readings, and failure to represent daytime blood pressure readings). In the present study, we provide evidence that the 24-hour mean blood pressure obtained through intraarterial blood pressure measurements in ambulatory patients provides a more accurate diagnosis (and perhaps a prognosis) of hypertension than that provided by cuff-obtained casual blood pressure measurement. Furthermore, despite a reduction in the amount and in the accuracy of the information obtained, blood pressure data provided by noninvasive blood pressure monitoring are also more accurate diagnostically than cuff-obtained casual blood pressure measurements. In 15 essential hypertensive patients in whom celiprolol, 400 mg once daily, was compared with placebo in a randomized double-blind crossover study, the use of noninvasive 24-hour automatic blood pressure monitoring showed that in responsive patients, celiprolol induced a sustained reduction in systolic and diastolic blood pressure throughout the 24 hours. The blood pressure reduction was also apparent during the night, despite the concomitant occurrence of a slight tachycardia. These findings demonstrate that once-daily administration of celiprolol provides an effective lowering of the 24-hour blood pressure profile. This dosing schedule can therefore be regarded as appropriate for antihypertensive therapy.
Adult↗
Experience with 24-hour ambulatory blood pressure monitoring in hypertension.
Traditional sphygmomanometric blood pressure measurements may lead to errors in the diagnosis of arterial hypertension due to a number of factors, among which are the alerting reaction and pressor response induced in patients by the doctor's visit. This phenomenon, as quantified in our laboratory by continuous intraarterial recordings, is responsible for an average rise in systolic and diastolic blood pressure of 27/15 mm Hg, a rise that does not seem to be reduced by simply desensitizing the patient by means of more frequent physician visits. Twenty-four hour ambulatory blood pressure monitoring may theoretically improve the diagnostic approach to hypertensive patients by overcoming some limitations of isolated cuff measurements. In recording intraarterial blood pressure in 108 ambulant hypertensive subjects, we have found that 24-hour blood pressure values are able to discriminate among patients with different degrees of target organ damage better than isolated sphygmomanometric readings. Moreover, these studies have indicated that 24-hour blood pressure variability may be as important as blood pressure mean values in the assessment of cardiovascular complications. In clinical practice, however, intraarterial blood pressure monitoring is not feasible, and only noninvasive recorders can be used. Use of these devices does not induce any alerting reaction in the patients and does not interfere with day-night blood pressure changes. Although it is characterized by intermittent readings, this approach is not incompatible with a precise estimate of 24-hour blood pressure mean values.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Pressure↗
Comparison of the cardiovascular effects of different laboratory stressors and their relationship with blood pressure variability.
Laboratory stressors are employed to assess the 'typical' cardiovascular reactivity to stress of a given subject. It is believed that this may assist in the diagnosis of hypertension and predict future development of blood pressure (BP) elevation. However, the internal consistency of the data obtained by laboratory stressing manoeuvres and their ability to reflect the effects of everyday stressful events occurring over a 24-h period have never been clearly established. We studied a group of ambulant normotensive and essential hypertensive in-patients who were undergoing prolonged intra-arterial blood pressure monitoring (Oxford method) to determine firstly, whether four routine laboratory stressors provided a homogeneous evaluation of subjects' reactivity and secondly, whether cardiovascular reactivity to these stressors reflected a tendency of BP to vary over a 24-h period. A significant correlation (P less than 0.01) was found between the pressor responses to mental arithmetic and the mirror drawing test and between the pressor responses to the cold pressor test and hand-grip. These correlations, however, were not close and responses to the 'mental' and 'physical' stressors were unrelated. The elevation in BP induced by laboratory stressors also did not correlate with the increase in BP accompanying stress elicited outside laboratory conditions (i.e. doctor's visit). The pressor effects of both the laboratory and the out-of-laboratory stressors showed little or no correlation with the 24-h absolute or per cent blood pressure variabilities, although for the stressors involving a mental challenge, a significant though not close correlation with daytime blood pressure variability was found. These data underline the limitations of laboratory tests in assessing cardiovascular reactivity to stress.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Twenty-four hour ambulatory intra-arterial blood pressure in normotensive and borderline hypertensive subjects.
A number of studies have shown that blood pressure values obtained by ambulatory monitoring are lower than those obtained in the doctor's office by cuff readings. However, there is still no suitable information on 'normal' 24-h ambulatory blood pressure values. In 19 normotensive and 13 borderline hypertensive subjects, defined by repeated office blood pressure measurements, we recorded intra-arterial blood pressure under ambulatory conditions for 24 h (Oxford method) in order (1) to assess the 24-h blood pressure values of normal subjects, and (2) to compare their 24-h blood pressure values with those of borderline hypertensive patients. In the normotensive subjects systolic, diastolic and mean ambulatory blood pressure values over 24 h were significantly lower than the corresponding office values, the differences being -15.0, -22.1 and -17.9 mmHg, respectively. In the borderline hypertensives 24-h ambulatory blood pressure was significantly lower than office readings. On average, the 24-h mean blood pressure of normotensive subjects was significantly lower than that of borderline patients (P less than 0.01). However, individual 24-h blood pressure values showed a considerable overlap. Thus, (1) ambulatory blood pressure values just below 140/90 mmHg do not necessarily mean that the blood pressure is in the normal range, the mean 24-h blood pressure of true normotensive subjects being much lower; (2) ambulatory blood pressure monitoring in patients with high office blood pressure readings may help to identify subjects whose 24-h mean values are indistinguishable from those of normotensives. However, the clinical relevance of these findings in the diagnosis of hypertension has to be validated by prospective clinical trials.
Adult↗
Circadian blood pressure variations and their impact on disease.
Errors can be made when blood pressure is measured only by a single clinic measurement. Such assessments bear only a limited relationship to mean 24-h blood pressure and do not provide complete information on potentially important features of the circadian pattern of blood pressure. Measurement of clinic or "casual" cuff blood pressure by the doctor can produce a large, variable, and unpredictable overestimation caused by the pressor response associated with anxiety in the patient. Single cuff measurements rarely reflect the 24-h mean and classifications of severity based on cuff measurements are therefore subject to a large degree of overlap. Estimation of the response to antihypertensive treatment by casual cuff measurements is therefore subject to the same criticisms. Although superiority of measurement of 24-h mean blood pressure has not been demonstrated in any prospective controlled study, several cross-sectional investigations have shown that complications of hypertension relate more closely to the 24-h mean than to casual measurements. The degree of variability of blood pressure during a 24-h period (which can only be measured by 24-h monitoring) bears a relation to target-organ damage that is independent of mean blood pressure value. Nighttime blood pressure mean has been shown to correlate with target organ damage approximately as closely as daytime blood pressure mean, implying that antihypertensive drugs must act during the night as well as the day if they are to influence the complications of hypertension.
Blood Pressure↗
Evaluation of the baroreceptor-heart rate reflex by 24-hour intra-arterial blood pressure monitoring in humans.
The baroreceptor control of the sinus node was evaluated in 10 normotensive and 10 age-matched essential hypertensive subjects in whom ambulatory blood pressure was recorded intra-arterially for 24 hours and scanned by a computer to identify the sequences of three or more consecutive beats in which systolic blood pressure (SBP) and pulse interval (PI) progressively rose (+PI/+SBP) or fell (-PI/-SBP) in a linear fashion, according to a method validated in cats. In normotensive subjects, several hundred +PI/+SBP and -PI/-SBP sequences of 3 beats were found whereas the number of sequences of 4, 5, and more than 5 beats showed a progressive drastic reduction. The mean slopes of +PI/+SBP (7.6 +/- 2.0 msec/mm Hg) and -PI/-SBP (6.4 +/- 1.5 msec/mm Hg) sequences were similar, but in both instances there was a large scattering of the values around the mean (variation coefficients: 64.2 +/- 4.7 and 62.6 +/- 2.4%). The slopes decreased as a function of the sequence length and baseline heart rate and increased to a marked extent during the night as compared with daytime values. All sequences were more rare (-33.2% for +PI/+SBP and -31.7% for -PI/-SBP) and less steep in hypertensive subjects (-40.3 and -36.2%, respectively), who failed to show the marked nighttime increase in slope observed in normotensive subjects. To our knowledge, these observations provide the first description in humans of the baroreceptor-heart rate reflex in daily life. This reflex is characterized by marked within-subject variations in sensitivity due in part to hemodynamic, temporal, and behavioral factors.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Neural control of circulation before and after intravenous urapidil in essential hypertension.
Drugs interfering with sympathetic influences on the cardiovascular system have been shown to effectively lower blood pressure in hypertension. However, sympathetic cardiovascular control is involved in blood pressure homeostasis, which means that these drugs may produce potential adverse haemodynamic effects that may reduce the benefit of their antihypertensive action. This paper summarises the results of a study in which we examined the effects of urapidil on the arterial baroreflex and the cardiopulmonary reflex in 6 essential hypertensive patients given 25 mg of the drug intravenously. The dose of the drug used caused a marked reduction in arterial blood pressure (direct measurement). However, pressor and depressor responses to carotid baroreceptor deactivation and stimulation (neck chamber device), respectively, were not modified when compared with those observed in the placebo period. This was also the case for increases and reductions in both forearm vascular resistance and plasma noradrenaline (norepinephrine) concentrations induced by deactivating and stimulating cardiopulmonary receptors, respectively. The pressor and tachycardic responses to handgrip and cold exposure were also unaffected by the drug. It is concluded that when administered at a clinically effective dose urapidil does not adversely affect major reflex mechanisms involved in neural cardiovascular regulation. This has favourable implications for the use of the drug in clinical practice.
Antihypertensive Agents↗
Evaluation of central and reflex cardiovascular control by beat-to-beat analysis of the 24 hour blood pressure signal in man.
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Blood Pressure↗
24-h ambulatory non-invasive blood pressure monitoring in the assessment of the antihypertensive action of celiprolol.
The well-known limitations of traditional sphygmomanometer blood pressure measurements have led to the development of a number of invasive and non-invasive 24-h blood pressure monitoring techniques which provide information on blood pressure in daily life. A non-invasive portable blood pressure monitor (IRC Spacelab S5300 monitor) was used to assess the antihypertensive action of celiprolol, 400 mg once daily, in a randomized, double-blind, crossover, placebo-controlled study. After a washout period of 7 days, 15 patients with mild or moderate essential hypertension were subjected to three 24-h blood pressure recordings: at the end of washout, and after 1 month of placebo and celiprolol treatment. In the 10 responsive patients, celiprolol reduced 24-h systolic blood pressure, diastolic blood pressure and heart rate by 6.8%, 8.1% and 2.7%, respectively, when compared with placebo. The reduction in blood pressure was also evident during the night and the antihypertensive action of celiprolol was maintained 24-h after administration. Celiprolol had no effect on 24-h blood pressure or heart rate variability and, therefore, did not produce any alteration in cardiovascular homeostasis. These results demonstrate that celiprolol is an effective once daily treatment for hypertension.
Adult↗
24-hour blood pressure monitoring: evaluation of Spacelabs 5300 monitor by comparison with intra-arterial blood pressure recording in ambulant subjects.
The accuracy of 24-h blood pressure values obtained by ambulatory monitoring via the Spacelabs 5300 device was evaluated by comparison with simultaneous 24-h intra-arterial blood pressure recording from the contralateral arm. The comparison was made in eight essential hypertensive subjects in whom non-invasive blood pressure was measured every 15 (day) or 30 min (night). The measurements were automatically and visually edited to eliminate artefactual readings and hourly and 24-h means were calculated separately for systolic and diastolic blood pressure. The corresponding intra-arterial blood pressure means were also calculated. In the group as a whole, hourly means obtained by the non-invasive device were similar or only slightly different from those recorded intra-arterially. The 24-h systolic blood pressure mean obtained non-invasively was not significantly different from that obtained intra-arterially (138.4 +/- 9.1 and 142.9 +/- 9.2 mmHg, respectively), nor were the corresponding 24-h diastolic blood pressure means significantly different (83.5 +/- 4.5 and 80.6 +/- 3.5 mmHg, respectively). However, in spite of these similarities, there were contrasting and often large discrepancies between non-invasive and intra-arterial values in individual subjects. For the 24-h systolic blood pressure mean the discrepancies ranged from 7.6 +/- 1.1 to 16.1 +/- 2.2 mmHg and for the 24-h diastolic blood pressure mean, from 3.5 to 13.2 mmHg. Thus, the Spacelabs 5300 device has a limited ability to correctly estimate ambulatory blood pressure in individual subjects. It may be better suited for the estimation of group blood pressures, but only because errors are smoothed by the summation of individual errors of opposing signs.
Adult↗