Experience with 24-hour ambulatory blood pressure monitoring in hypertension

Perioperative SBP changes during orthopedic surgery in the elderly: clinical implications

OBJECTIVES

We aimed to determine SBP changes during the perioperative period of a scheduled knee surgery under regional anesthesia and the extent of perioperative (in-hospital) white-coat effect.

METHODS

All patients (aged ≥60 years) underwent clinic SBP measurements during both cardiological and anesthesiological visits, while home SBP the week before admission was obtained. Clinic SBP was registered just before surgery, during surgery and reanimation. Ambulatory monitoring was also performed (12 h before surgery to 6-8 h after surgery). One month after discharge, clinic SBP was measured at hypertension unit.

RESULTS

Eligible participants (N = 50, mean age 74 ± 7 years, 34% men, 26% with history of cardiovascular disease) had higher SBP during the anesthesiologic than the cardiological evaluation (157 ± 23 vs. 144 ± 18 mmHg, P < 0.001), and the former levels were almost identical to those clinically measured just before surgery. A significant white-coat effect between ambulatory and clinic measurements just before surgery (16.4 ± 21 mmHg, P < 0.001) and between entire ambulatory recording and clinic BP measurements the day before surgery (12.4 ± 16 and 24.8 ± 21 mmHg for cardiologic and anesthesiologic visit, respectively, P < 0.001 for both) was noticed, whereas intraoperatively the white-coat effect faded away. There was a greater SBP decline during surgery in patients aged more than 75 years compared with younger, whereas selective treatment discontinuation (except beta blockers and calcium channel blockers) did not modulate SBP trajectories.

CONCLUSION

The significant white-coat effect observed in scheduled noncardiac surgery is clinically important and the home BP measurement performed before surgery or ABPM, highly reflects the hypertensive burden of the patient. Blood pressure decrease during surgery is quite pronounced especially in patients aged more than 75 years. Aggressive BP lowering should be avoided.

Diagnostic value and cost-benefit analysis of 24 hours ambulatory blood pressure monitoring in primary care in Portugal

Background

Hypertensive patients (HTs) are usually attended in primary care (PC). We aimed to assess the diagnostic accuracy and cost-benefit ratio of 24-hour ambulatory blood pressure monitoring (ABPM) in all newly diagnosed hypertensive patients (HTs) attended in PC.

Methods

In a cross-sectional study ABPM was recorded in all 336 never treated HTs (Office BP ≥140 and/or ≥ 90 mm Hg) that were admitted during 16 months. Since benefits from drug treatment in white-coat hypertension (WCH) remain unproven, a cost benefit estimation of a general use of ABPM (vs absence of ABPM) in HTs was calculated comparing the cost of usual medical assistance of HTs only diagnosed in office with that based both on refraining from drug treatment all subjects identified as WCH and on the reduction by half of the frequency of biochemical exams and doctor visits.

Results

Women were 56%, age 51 ± 14 years and BMI 27 ± 4 Kg/m2. Out of these, 206 were considered as true HTs, daytime ABPM ≥ 135 and/or ≥85 mm Hg and 130 (38,7%) were identified as having white coat hypertension (WCH), daytime ABPM <135/85 mm Hg. Versus HTs, WCH group showed higher percentage of women (68% vs 51%) and lower values of an index composed by the association of cardiovascular risk factors. We estimated that with ABPM total medical expenses can be reduced by 23% (157.500 euros) with a strategy based on ABPM for 1000 patients followed for 2 years.

Conclusions

In PC, the widespread use of ABPM in newly diagnosed HTs increases diagnostic accuracy of hypertension, improves cardiovascular risk stratification, reduces health expenses showing a highly favourable benefit-cost ratio vs a strategy without ABPM.

The nurse's role and skills in hypertension care: a review

The aim of this review was to examine studies on nursing in hypertension care to find out the nurse's role and skills. Articles were searched during the period 1966-1997. About 650 abstracts were read, and 148 were selected for examination. Forty-two articles were judged to be relevant for the study. The role of the nurse in programs was described as that of a team member, an educator in nonpharmacological treatment, and a translator for the physician with a holistic and psychosocial approach. A nurse participating in hypertension care promoted blood pressure reductions as the patients decreased their weight and sodium intake, stopped smoking, increased their physical activity, took their medication more correctly, and returned for follow-up visits more frequently, and the cost of drugs and visits to the physician decreased. Local programs for hypertension care should be developed with nurses' holistic and psychosocial approach and skills taken into account. More well-designed studies are needed to develop nursing care for hypertensive patients.

Increase in nocturnal blood pressure and progression to microalbuminuria in type 1 diabetes

BACKGROUND

Patients with type 1 diabetes mellitus and microalbuminuria often have elevated blood pressure while they are asleep, but it is not known whether the elevation develops concomitantly with microalbuminuria or precedes it.

METHODS

We monitored 75 adolescents and young adults who had had type 1 diabetes with normal urinary albumin excretion and blood pressure for more than five years. Ambulatory blood-pressure monitoring was used to assess blood pressure at the initial evaluation and about two years later, at which time all subjects had normal urinary albumin excretion. Subsequently, subjects were monitored for the development of microalbuminuria.

RESULTS

Microalbuminuria developed in 14 subjects, whereas the other 61 continued to have normal urinary albumin excretion. The mean (+/-SD) systolic pressure during sleep increased significantly in the subjects who ultimately had microalbuminuria (from 109.9+/-11.3 to 114.9+/-11.7 mm Hg, P=0.01) but not in the subjects with normal albumin excretion (from 106.0+/-8.8 to 106.4+/-14.8 mm Hg). The risk of progression to microalbuminuria was examined in relation to the ratio of systolic pressure during sleep to systolic pressure in the daytime. A ratio of 0.9 or lower, used to define a normal fall in nocturnal pressure, had a negative predictive value of 91 percent for the development of microalbuminuria. Moreover, the risk of microalbuminuria was 70 percent lower (95 percent confidence interval, 44 to 110 percent) in subjects with a ratio of 0.9 or less than in those with a ratio higher than 0.9 (P=0.01).

CONCLUSIONS

In persons with type 1 diabetes, an increase in systolic blood pressure during sleep precedes the development of microalbuminuria. In those whose blood pressure during sleep decreases normally, the progression from normal albumin excretion to microalbuminuria appears to be less likely.

Blood pressure measurement--an observational study of 21 public health nurses

The purpose of this study was to observe how public health nurses perform blood pressure measurement. Structured observations were made of 21 randomly selected public health nurses while they performed three blood pressure measurements. The public health nurses used an overall correct method for blood pressure measurement. Five nurses out of 21 used the Tri-cuff but the soft cuff was most frequently used. When choosing the breadth of the cuff, 10 nurses decided by eye and not by the marks on the cuff. To ensure a completely correct method additional information is needed by nurses.

Sleep structure in essential hypertensive patients: differences between dippers and non-dippers

The objective of this study was to determine whether the macrostructure and microstructure of sleep were altered in non-dipper essential hypertensive patients. Patients included 9 non-dipper essential hypertensive patients and 10 dippers. We measured blood pressure beat-to-beat by Finapres and all stages of sleep by polysomnografically recording simultaneously during spontaneous nocturnal sleep. We analysed blood pressure pattern for 4-min long random periods while the patients were awake and during all stages of sleep; sleep-efficiency (SE), sleep-latency (SL), delta sleep-latency (delta-SL), REM sleep-latency (REM-SL), St. 1, St.2, St.3, St.4 and REM duration and percentage (%) values, and microstructural aspects of sleep (arousal and microarousal temporisation and features). Dipper patients showed a fall in blood pressure (BP) greater than 10% in all stages of NREM sleep; in the non-dipper patients BP fell by less than 10% of waking values in all NREM stages. REM sleep as well as HR were similar in both groups during all stages of sleep. Non-dippers showed the same number of arousals but more microarousals than dippers (p < 0.001). During and after microarousals BP and HR increased in non-dippers, but showed light variation in dippers. Microarousals induced several stage shifts towards lighter sleep. For this reason non-dippers spent less time in stage 4 than dippers (p < 0.001). In conclusion, non-dipper essential hypertensive patients are a subset of patients with central sympathetic hyperactivity responsible for quantitative and qualitative alteration of sleep.

Association of body mass index and regional fat distribution with blood pressure investigated by 24-hour ambulatory blood pressure monitoring in android-type obese

In 46 female outpatients with android-type obesity, body mass index (BMI) 36.6 +/- 1.0, waist to hip ratio (WHR) > 0.86, and normal glucose tolerance (NGT) who were hypertensive at entry study [blood pressure (BP) > 140/90 mm Hg] and in 10 clinically healthy, nonobese, normotensive women, we evaluated the relationship between BMI, fat mass, WHR, fasting blood glucose, sum of blood glucose levels during oral glucose tolerance test and casual BP levels, 24-h ambulatory BP monitoring (ABP) parameters as the 24-hour mean, day-time mean, night-time mean and, by using a periodic model of cosine regression, MESOR (midline estimating statistic of rhythm), amplitude, acrophase, and baric impact. In android obese women, a negative correlation between ABP levels (day-/night-time, MESOR, and baric impact of systolic BP; night-time and MESOR of diastolic BP) and BMI has been documented. A positive correlation between systolic BP (casual, night-time mean, MESOR, amplitude, and baric impact), diastolic baric impact, and the WHR has been found. No correlation has been demonstrated between ABP monitoring parameters, and BMI, body fat, and WHR in the control group. Our data could suggest that, when enrolling obese subjects, it must be taken into account that obesity is a heterogeneous disorder. There are in fact obese subjects with normal or impaired glucose tolerance, as well as diabetics with moderate to severe obesity and with gynecoid or android-type obesity. In our android obese subjects with NGT, the WHR rather than the BMI was found to be a better predictor of hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Altered blood pressure during sleep in normotensive subjects with type I diabetes

This study was designed to examine the circadian pattern of blood pressure in children and young adults with type I diabetes who were completely normotensive by standard criteria. Forty-five patients and the same number of age- and sex-matched control subjects were studied. In diabetic children of 10-14 years of age, the nocturnal fall in systolic and diastolic blood pressures was intact. In diabetics of 15-20 years of age, the fall in systolic blood pressure was blunted; in diabetics of 21-37 years of age, the fall in both systolic and diastolic blood pressures during sleep was blunted. When data from all diabetic subjects were pooled and analyzed in a multiple linear regression model, mean blood pressure during sleep correlated best with urinary albumin excretion (r = 0.60). On the basis of this finding, we subdivided our patients into two groups: a microalbuminuric group (urinary albumin excretion > 30 mg per 24 hours; mean, 160.3 +/- 29.7; n = 11) and a normoalbuminuric group (urinary albumin excretion < 30 mg per 24 hours; mean, 6.6 +/- 6.5; n = 34). Both systolic and diastolic blood pressures during sleep were higher in microalbuminuric (121.1 +/- 3.3 and 69.3 +/- 2.5 mm Hg, respectively) than in normoalbuminuric diabetics (114.2 +/- 1.8 and 60.1 +/- 1.2 mm Hg, p < 0.05) or control subjects (113.3 +/- 1.2 and 60.1 +/- 1.2 mm Hg, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium antagonists in the treatment of arterial hypertension

Calcium antagonists are widely used antihypertensive agents whose hemodynamic effects consist of a reduction in blood pressure and peripheral vascular resistance that is associated, in case of short-term administration, with a reflex increase in heart rate and cardiac output. These compounds exert several additional positive effects besides blood pressure reduction. Among them, calcium antagonists exert their antihypertensive effect without negatively interfering with both central and reflex neural control of circulation. The only change in baroreflex function observed during the administration of these compounds is a resetting of the baroreflex toward the lower blood pressure values achieved by treatment. New calcium antagonists of the dihydropyridine type are characterized by a greater vascular selectivity, and by the ability to exert a persistent blood pressure reduction throughout the 24 hours when administered in a single oral dose. The latter feature can be properly assessed by means of ambulatory blood pressure monitoring techniques.

Feasibility of ambulatory, continuous 24-hour finger arterial pressure recording

We tested Portapres, an innovative portable, battery-operated device for the continuous, noninvasive, 24-hour ambulatory measurement of blood pressure in the finger. Portapres is based on Finapres, a stationary device for the measurement of finger arterial pressure. Systems were added to record signals on tape, to alternate measurements between fingers automatically each 30 minutes, and to correct for the hydrostatic height of the hand. We compared the pressure as measured by Portapres with contralateral intrabrachial pressure measured with an Oxford device. Results were obtained in eight volunteers and 16 hypertensive patients. Time lost due to artifact was about 10% for each device. In two patients a full 24-hour Oxford profile was not obtained. In the remaining 22 subjects finger systolic, diastolic, and mean pressures differed +1 (SD 9), -8 (6), and -10 (6) mm Hg, respectively, from intrabrachial pressure. These diastolic and mean pressure underestimations are similar to what was found earlier for Finapres, are typical for the technique, and are systematic. Avoiding brisk hand movements resulted in fewer waveform artifacts. The hand had to be kept covered to continue recording at low outside temperatures. Sleep was not disturbed by Portapres, and arterial pressure showed a marked fall during siesta and nighttime. There were no major limitations in behavior, and no discomfort that originated from continuous monitoring was reported. Measurements continued normally during physical exercise. Portapres provides for the first time continuous 24-hour, noninvasive ambulatory blood pressure waveform monitoring and offers real and obvious advantages over current noninvasive and invasive devices.

Ambulatory blood pressure monitoring and circadian variation of cardiovascular disease; clinical and research applications

Ambulatory blood pressure monitoring is an evolving technology. It has an established role in the diagnosis of hypertension, the clinical management of selected patients, and in the evaluation of new medication. From continuous recording much has been learned about the circadian nature of blood pressure and heart rate. Future research holds promise for a greater understanding of the mechanisms and treatment of cardiovascular disease. The purpose of this short review is to describe the development of ambulatory blood pressure monitoring, and outline some of its important contributions to date; and also to explore the research potential and clinical utility of advanced intravascular monitoring techniques, such as the continuous recording of pulmonary artery pressure in ambulant patients.

Hyperinsulinaemia in hypertension and diabetes mellitus: a chronobiological approach

Blood pressure was continuously recorded for 24 h in 31 non-insulin-dependent diabetic men with borderline, mild, or moderate systolic and/or diastolic hypertension. A 2-h oral glucose tolerance test was also performed with blood glucose, serum insulin and C-peptide determination at 30-min intervals. Significant correlations were found between fasting and post-glucose integrated area of blood glucose, insulin and C-peptide concentrations versus blood pressure measures. Total insulin area appeared to correlate significantly with diastolic measures [casual, daytime, night-time, mean computational (mesor), hyperbaric impact and percent time elevation], mean blood pressure, and mesor and hyperbaric impact systolic measures. It is concluded that the more accurate assessment of the circadian pattern of blood pressure by a chronobiological procedure allowed the existence of close correlations between metabolic and blood pressure measures to be established, confirming the importance of hyperinsulinaemia in the pathophysiology of arterial hypertension.

Circadian rhythm of blood pressure in congestive heart failure and effects of ACE inhibitors

In 33 patients with heart failure (NYHA II-III), the 24-h blood pressure rhythm was examined before and after the titration period of two ACE inhibitors. Blood pressure was measured by the oscillometric method using the blood pressure monitor 90202 from SpaceLabs, Inc. The measurements were taken from 06:00 to 22:00 h every 20 min and from 22:00 to 06:00 h every hour. Patients were randomized to therapy with either captopril (group 1, n = 17) or enalapril (group 2, n = 16). The average daily dosage of captopril was 41 +/- 3 mg given in three divided doses (08:00, 12:00, and 17:00 h). The mean dose of enalapril was 8 +/- 1 mg once daily (08:00 h). Serum electrolytes, serum creatinine, and plasma renin activity were measured before and during therapy with both ACE inhibitors. Twenty-four-hour blood pressure measurements were taken before and on the fifth day of treatment with ACE inhibitors. Both groups were not different with respect to the degree of heart failure, the concomitant medication, and the 24-h profiles of blood pressure and heart rate before initiation of ACE inhibition. The 24-h blood pressure values on day 5 were consistently below the pretreatment values (p less than 0.005) in both groups. Both groups did not differ significantly during ACE inhibition in their 24-h blood pressure and heart rate profiles. In both groups, the mesor of the systolic and diastolic blood pressure decreased significantly by the same degree (by 4.7/5.1 mmg Hg in group 1 and 6.4/4.1 mm Hg in group 2). The systolic/diastolic blood pressure amplitude decreased slightly in both groups. Before treatment, serum sodium, potassium, and creatinine were within the normal range. The increase in potassium (0.5 +/- 0.1 mmol/L) reached statistical significance (p less than 0.01) only in the captopril group, whereas it was not significant in the enalapril group (0.1 +/- 0.1 mmol/L). Serum creatinine was not significantly altered by both ACE inhibitors. No relationship could be found between the changes in serum potassium or creatinine and the mean of the 24-h blood pressure values during ACE inhibition. Captopril and enalapril showed comparable blood pressure profiles and similar effects on renal function at the end of the titration on day 5. It can therefore be concluded that the effects on blood pressure rhythm and renal function are similar with a single daily dose of enalapril compared to captopril given three times daily.

Documentation of the effective length of action of antihypertensive treatment

The technique of automated ambulatory blood pressure (BP) monitoring offers an innovative means for measuring BP throughout the 24-hour period. Recently available compact monitoring instruments have been shown to be accurate and to provide reproducible measurements of the circadian BP pattern. The monitoring procedure is advantageous in that it minimizes or avoids placebo effects during therapeutic trials. Moreover, its power makes it possible to draw statistically valid conclusions regarding efficacy in fewer patients than would be required if conventional methods were used. This procedure also enhances the diagnosis of hypertension by identifying patients with "office" or "white coat" hypertension, and thereby facilitates assessment of treatment effects in those patients who are truly hypertensive. Automated monitoring measures BP at critical times of the day, including the preawakening and early morning hours, and it enables peak and trough antihypertensive drug effects to be carefully quantified. Since patient compliance appears to be enhanced with once- or twice-daily dosing, antihypertensive agents with long durations of action (24 hours) are of considerable interest. This report reviews some recent studies in which the monitoring technique has been used to measure the efficacy and duration of action of differing antihypertensive drugs.