Non-invasive Blood Pressure Recordings Research Articles

Evaluation of the safety and efficacy of deep sedation for electrophysiology procedures administered in the absence of an anesthetist.

Several procedures performed in the electrophysiology laboratory (EP lab) require surgical manipulation and are lengthy. Patients undergoing such procedures usually receive general anesthesia or deep sedation administered by an anesthesiologist. In 536 consecutive procedures performed in the EP lab, we assessed the safety and efficacy of deep sedation administered under the direction of an electrophysiologist and in the absence of an anesthetist. Patients were monitored with pulse oximetry, noninvasive blood pressure recordings, and continuous ECGs. The level of consciousness and vital signs were evaluated at 5-minute intervals. Deep sedation was induced in 260 patients using midazolam, phenergan, and meperidine, then maintained with intermittent dosing of meperidine at the following mean doses: midazolam 0.031 +/- 0.024 mg/kg; phenergan 0.314 +/- 0.179 mg/kg; and meperidine 0.391 +/- 0.167 mg/kg per hour. In the remaining 276 patients, deep sedation was induced with midazolam and fentanyl and maintained with a continuous infusion of fentanyl at a mean dose of 2.054 +/- 1.43 micrograms/kg per hour. Fourteen patients experienced a transient reduction in oxygen saturation that was readily reversed following administration of naloxone. An additional 11 patients desaturated secondary to partial airway obstruction, which resolved after repositioning the head and neck. Fourteen patients experienced hypotension with fentanyl. All but one returned to baseline blood pressures following an infusion of normal saline. No patient required intubation and no death occurred. Only three patients had recollection of periprocedure events. No patient remembered experiencing pain with the procedure. Hospital stays were not prolonged as a result of the sedation used. (1) deep sedation during EP procedures can be administered safely under the guidance of the electrophysiologist without an anesthetist present; (2) the drugs used should be readily reversible in case of respiratory depression; and (3) this approach may reduce the overall cost of the procedures in the EP lab, maintaining adequate patient comfort.

Evaluation of the IITC tail cuff blood pressure recorder in the rat against intraarterial pressure according to criteria for human devices

National standards govern the manufacture and marketing of medical devices in the United States, including those for indirect blood pressure measurement in man. There are no comparable standards for devices for recording in laboratory animals. Noninvasive tail cuff blood pressure (BP) recording in the rat is widely accepted, but beset by methodologic difficulties. Intraarterial recording is regarded as the “gold standard” but is invasive and also susceptible to methodologic error. We compared the IITC Mark 12 photoelectric/oscillometric tail cuff system (IITC Life Sciences, Woodland Hills, CA) versus simultaneous femoral intraarterial recordings in spontaneously hypertensive rats, during anesthesia and 1 to 2 days after recovery (150 recordings under each condition), according to the guidelines for human data collection and analysis suggested by the American National Standard for automated sphygmomanometers. Within- and between-observer disagreements in estimates made by two observers from 40 anesthetized recordings were less for intraarterial measurements than for the tail cuff method. Within-observer differences (mean ± SD of differences [SDD]) for systolic, diastolic, and mean pressure were 0 ± 1, 0 ± 1, and 0 ± 1 mm Hg for intraarterial versus −1 ± 3, 0 ± 8, and 0 ± 5 mm Hg for tail cuff. Between-observer differences were 0 ± 2, 0 ± 1, and 6 ± 2 mm Hg versus 5 ± 4, 13 ± 7, and 0 ± 5 mm Hg, respectively. Differences between tail cuff and intraarterial methods were 16 ± 13, −5 ± 11, and 2 ± 8 mm Hg in anesthetized animals and 8 ± 14, −5 ± 9, and 0 ± 9 mm Hg in conscious animals (39% to 82% of differences exceeded 5 mm Hg). The upper limits of clinically acceptable disagreement in the American National Standard are: mean of 5 mm Hg, SDD of 8 mm Hg. The disagreement between tail cuff and intraarterial recordings cannot be ascribed to either method with certainty. These findings do not support the manufacturer's guarantee of tail-cuff readings within “5 mm Hg of intraarterial.” Inaccuracy and unreliability of devices intended for laboratory animal use have considerable scientific, fiscal, and ethical implications. Marketing of these devices should also be governed by rigorous standards.

Improvements of Noninvasive Long-term Blood Pressure Recording

Improvements of Noninvasive Long-term Blood Pressure Recording

Blood pressure analysis.

Arterial blood pressure is influenced by sleep-related breathing disorders. As cardiovascular consequences can be diagnosed by an accurate recording and analysis of blood pressure, new recording methodologies and an approach to analysis are presented here. Invasive continuous blood pressure recording is the common reference for all methodologies. As blood pressure varies rapidly in parallel with sleep-related breathing disorders it is indispensible to record blood pressure continuously. To introduce non-invasive methodology the Finapres system was used during sleep studies; a validation study showed severe limitations. This study was followed by the validation of an improved system called Portapres, which is portable, has two finger cuffs and a hydrostatic height compensation. Analysis of continuous blood pressure in patients with sleep apnoea is carried out to detect mechanisms which influence the cardiovascular risk. Spectrum analysis of systolic blood pressure showed two different major oscillations present in patients with obstructive sleep apnoea. One oscillation (<0.06 Hz) occurs in parallel with each apnoeic episode and the other oscillation (0.2-0.4 Hz) occurs in parallel with the obstructive efforts during each apnoea and in parallel with respiration during periods of snoring. These two oscillations were so specific that the use of non-invasive continuous blood pressure recording allowed an estimation of the extent of underlying breathing disorders, and assessment of cardiovascular risk in a patient with obstructive apnoea in terms of hypertension and on the basis of ambulatory monitoring.

Reduction in sympathetic activity after long-term CPAP treatment in sleep apnoea: cardiovascular implications

Twelve patients with severe obstructive sleep apnoea were included in an open, long-term, prospective, follow-up study addressing the effects of nasal continuous positive airway pressure (CPAP) on sympathetic activity, cardiac structure and blood pressure. Plasma norepinephrine (P-NE) (daytime at rest), daytime and night-time urinary excretion of NE (U-NE), vanylmandelic acid and metanephrines, together with 24 h noninvasive blood pressure (BP) recording and Doppler-echocardiography, were assessed before and after a mean of 20.5 (range 14-26) months of CPAP. Average self-reported use of CPAP was 89% (range 65-100%) of time spent in bed. Resting daytime P-NE ranged 0.35-0.83 ng.ml-1, which is elevated compared to healthy controls. Only night-time U-NE, mean daytime BP and average 24 h BP were related to severity of OSA. Night-time metanephrine was related to daytime and night-time diastolic, as well as night-time systolic, BP. Left ventricular mass index (LVMI) at baseline was correlated to daytime systolic BP and P-NE. Long-term CPAP treatment reduced biochemical markers of sympathetic activity. P-NE decreased by approximately 50%, and daytime and night-time vanylmandelic acid and metanephrine by 32-54%. In contrast, there were no overall reductions in BP or LVMI. It is concluded that obstructive sleep apnoea is associated with high sympathetic activity both during sleep and waking periods. Urinary metanephrine excretion seemed to reflect blood pressure, but neither daytime nor night-time catecholamine excretion was directly related to disease severity in patients with severe obstructive sleep apnoea.(ABSTRACT TRUNCATED AT 250 WORDS)

Immediate cardiovascular responses to orthostasis in the early and late months after cardiac transplantation

Immediate post-standing (< 30 s) heart rate and blood pressure regulation was studied in patients in the early (2 ± 2 months, n = 10) and late months (49 ± 18 months, n = 30) after orthotopic heart or heart and lung transplantation with continuous non-invasive blood pressure (Finapress) and ECG recordings, and was compared to 15 healthy subjects. Heart rate acceleration on standing was absent in the early post-transplantation period. Modest, delayed heart rate acceleration (maximum 12 ± 8 beats/min) was seen late post-transplantation. Subgroup analysis showed that 15 patients late post-ttransplantation had limited (maximum 6 ± 3 beats/min) heart rate acceleration, 11 patients showed maximum heart rate acceleration between 11 and 19 beats/min and 4 patients showed heart rate acceleration comparable in magnitude with that of normal subjects (maximum 28 ± 5 beats/min). The blood pressure transients were comparable in the 3 groups, with a tendency for greater drop and smaller overshoot in systolic blood pressure in transplant subjects. The findings of normal blood pressure transients in the setting of extensive afferent cardiac denervation questions the role of intracardiac (intraventricular) receptors in reflex blood pressure regulation. The development of heart rate responsiveness is compatible with sympathetic reinnervation in many patients in the late post-transplantation period; however, an intrinsic cardiac mechanism may also be possible.

Ambulatory Blood Pressure Recording

Problems with therapeutic conclusions based on intervention trials, Andrew J.S. Coats and Peter Sleight from invasive to non-invasive ambulatory blood pressure recording, Edward Bernard Raferty ambulatory blood pressure and assessment of cardiovascular risk, Dorothee Perloff and Maurice Sokolow how to deal with blood pressure variability, G. Parati et al borderline hypertension, Michael A. Weber et al home monitoring of blood pressure - an alternative to ambulatory monitoring, Thomas G. Pickering efficacy assessment of antihypertensive therapy, Bernard Waeber et al a pragmatic look at ambulatory blood pressure monitoring, Hans R. Brunner et al.

Twenty-Four-Hour Ambulatory Noninvasive Continuous Finger Blood Pressure Measurement with PORTAPRES

PORTAPRES model 1 is a portable 24 h continuous noninvasive blood pressure recorder based on the same principles as FINAPRES, the volume-clamp method of Peñaz and the physiocal criteria of Wesseling. In addition, PORTAPRES measures two adjacent fingers in alternation every 30 min and automatically corrects hydrostatic effects due to height changes of the measured fingers. The device measures 255 x 210 x 60 mm and weights about 3,000 g, including a lithium battery pack and a TEAC cassette FM instrumentation tape recorder to record the finger pressure wave form, the height signal, and beat-to-beat derived systolic, mean and diastolic pressure as well as heart rate. It appears to be an excellent new tool for cardiovascular research in humans. In a randomized, placebo-controlled, double-blind, crossover study the effect of oral administration of 2.5 mg cilazapril, a new potent long-acting, nonsulfhydryl-group angiotensin converting enzyme (ACE) inhibitor, given once daily for 7 days, was investigated in 16 healthy young men (mean age 25.3 +/- 1.6 years). Finger blood pressure and heart rate were measured with PORTAPRES for 24 h during everyday life and during standardized laboratory tasks, once about 1 to 2 h A.M. and once about 10 to 11 h P.M. once about 1 to 2 h A.M. and once about 10 to 11 h P.M. after drug administration. Physical activity was controlled by integrated thigh-EMG. Using stepwise multiple linear regression analysis it was shown that based on 64 s mean values, this measure of physical activity explains 34-77% of the heart rate variance within 24 h (median 53%), 10-52% (31%) of systolic, and 4-38% (25%) of diastolic blood pressure variance when up to 20 time lags of the EMG signal were introduced as possible predictors. This indicates that varying degrees of physical activity have a great impact on everyday blood pressure and heart rate. After one week cilazapril did not alter 24-h means of systolic and diastolic blood pressure or heart rate significantly, but reduced 30 min averages of both systolic and diastolic blood pressure by 6-10 and 4-6 mm Hg between 1 1/2 and 4 or 6 h after drug administration respectively during everyday life (p = 0.0067-0.066) without changing heart rate. On adjusting cardiovascular variables for the effects of physical activity, this blood pressure reduction was confirmed.(ABSTRACT TRUNCATED AT 400 WORDS)

Twenty-four hour blood pressure profiles in hypertensive patients following various formulations and dosage regimens of felodipine

The blood pressure lowering capacity of felodipine administered either as extended release tablets once or twice daily or as plain tablets twice daily has been compared in a double-blind, three-way cross-over study in 16 hypertensive patients. All the patients were on long-term treatment with 10 or 20 mg felodipine daily and other antihypertensive therapy (mainly beta-blockers) was allowed if it was kept unchanged. Non-invasive blood pressure and heart rate recordings were obtained throughout 24 hour periods using an Accutracker ambulatory system. The 24 h mean systolic and diastolic blood pressures after extended release tablets o.m. did not differ significantly from those after extended release tablets b.d. or plain tablets b.d. There was a tendency for the extended release tablets given o.m. to reduce blood pressure somewhat more in the morning, and for the extended release tablets b.d. to reduce blood pressure more during the night than the other treatments. Mean 24 h heart rate after all treatments was comparable. Manual recordings confirmed these results. Blood pressure was well-controlled throughout the 24 h period by all three treatments. The extended release tablets tended to give less extreme plasma concentrations of felodipine. This may be of value for patients with adverse vasodilator effects. For a majority of hypertensive patients the adequacy of blood pressure control and the simplicity of once daily dosing will favour the extended release tablet given once daily.

165. Frequent non-invasive ambulatory blood pressure recordings do not alter sleep quality in young men

165. Frequent non-invasive ambulatory blood pressure recordings do not alter sleep quality in young men

A Multicenter Evaluation of the A&amp;D TM-2420 Ambulatory Blood Pressure Recorde

The A&D TM-2420 (A&D Engineering, Milpitas, CA) is an automatic, portable, noninvasive blood pressure (BP) recorder which uses a dual microphone system for the detection of Korotkoff sounds. Its accuracy and clinical performance were assessed in a multicenter study that also addressed issues such as observer agreement and the effects of age, arm circumference, heart rate, posture, and blood pressure level on the observer-device differences. We compared 906 simultaneous, same-arm BP measurements in 151 subjects using the TM-2420 versus two skilled clinicians per site using a teaching stethoscope. The agreement between the TM-2420 and mercury column determinations were within 10 mm Hg for 86 to 91% of systolic readings and 91 to 94% of diastolic readings, depending on the posture; a level of agreement which would receive a 'B+' grade from the recent British Hypertension Society guidelines. The limits of agreement (2 standard deviations about the mean difference) for systolic BP between observers and the TM-2420 tended to be greater for the standing position (-20 to 15 mm Hg) compared to supine (-14 to 12 mm Hg) and seated (-13 to 8 mm Hg) positions. Limits of agreement between the observers and device were not dependent upon age, heart rate, arm size, or blood pressure level. Twenty-four-hour blood pressure monitoring in two of the four centers demonstrated an error code rate of 3.4%, excluding 'retries' that are one of the device's features. These data demonstrate an acceptable level of accuracy and performance of the sixth generation of the TM-2420 for use in clinical practice and research.(ABSTRACT TRUNCATED AT 250 WORDS)

Twenty-four-hour variation of blood pressure in vascular dementia of the Binswanger type.

Using a noninvasive portable blood pressure recorder, we compared 24-hour variations of blood pressure among 1) 35 patients with Binswanger-type dementia, 2) 43 with lacunar-type dementia, 3) 26 with a single lacunar stroke, and 4) 30 controls. Each group was divided into antihypertensive-treated and -untreated subgroups. Among the untreated subgroups, patients with Binswanger-type dementia had significantly greater 24-hour mean systolic blood pressures, 24-hour systolic blood pressure standard deviations, and maximal systolic blood pressure variations than the controls (p less than 0.05). Among the treated patients, blood pressure variability increased similarly in all subgroups with cerebrovascular lesions compared with the controls (p less than 0.05). The nocturnal blood pressure decreases seen in the controls were absent among both untreated and treated patients with Binswanger- or lacunar-type dementia (p less than 0.05). Our results suggest the importance of hypertension, short-term variations in blood pressure, and a sustained nighttime elevation of blood pressure for the pathogenesis of both Binswanger-type and lacunar-type dementia in patients receiving antihypertensive medication.

165. Frequent non-invasive ambulatory blood pressure recordings do not alter sleep quality in young men

165. Frequent non-invasive ambulatory blood pressure recordings do not alter sleep quality in young men

Cardiac baroreflex function during postural change assessed using non-invasive spontaneous sequence analysis in young men

The aim was to assess the value of baroreflex sensitivity estimates calculated from analyses of spontaneous systolic blood pressure and pulse interval sequences derived from continuous non-invasive finger blood pressure recordings during sitting and active standing. Continuous recordings of digital systolic blood pressure and pulse interval were obtained non-invasively using a Finapres FD5 during 5 min trials of sitting and standing. Subjects were healthy males aged 19-28, divided into those with "high" normal (n = 18) and "low" normal (n = 17) blood pressure. Recordings were scanned for spontaneous sequences of three or more cardiac cycles over which systolic blood pressure increased progressively in conjunction with prolonged pulse interval, or decreased while pulse interval became shorter. Regressions between blood pressure and pulse interval (r greater than 0.80) provided estimates of cardiac baroreceptor reflex control. Computations were carried out with concurrent blood pressure and pulse interval measurements, and with a delay or lag of one and two cycles between the two variables. Pulse interval was reduced from an average 870.3 ms sitting to 571.3 ms on standing. Mean baroreflex sensitivity while sitting averaged 17.5 ms.mm Hg-1 at a delay of one cycle, failing to 7.65 ms.mm Hg-1 with standing. The decrease in sensitivity was correlated with the change in pulse interval between trials. The number of sequences was also significantly reduced with standing as opposed to sitting. Three cycle sequences were most frequent, with a lesser number of sequences involving 4, 5, and 6 or more cycles. No significant differences between "high" and "low" normal blood pressure groups were observed. The analysis of spontaneous sequences from non-invasive recordings may provide useful information concerning cardiac baroreflex control in different postural and behavioural states. A lag of one cycle between systolic blood pressure and pulse interval may provide the most representative estimates of baroreflex sensitivity.

The assessment of portable, non-invasive blood pressure recorders

As the field of ambulatory blood pressure monitoring has broadened and become increasingly used for clinical hypertension research and practice over the last decade, the number and variety of recorders have increased at least 10-fold. However, now that the use of these recorders is fairly widespread in many nations, regulatory groups, investigators and editors of research journals are beginning to seriously question the absence of a rigorous, non-biased assessment of these devices before their use in clinical research or practice

Non-invasive continuous finger blood pressure measurement during orthostatic stress compared to intra-arterial pressure

The aim of the study was to evaluate whether invasive blood pressure responses to orthostatic stress can be replaced by non-invasive continuous finger blood pressure responses. DESIGN - Intrabrachial and Finapres blood pressures were simultaneously measured during passive head up tilt and during active standing from the supine or sitting position in healthy volunteers. Subjects (n = 11) were healthy males aged 22-40 years, mean age 30 years. Beat to beat values of systolic, diastolic, and mean arterial pressures were calculated for both methods of measurement and the differences compared during a 30 s control period before, and during the first 120 s after, the change of posture. In the control period the difference between finger pressure and intra-arterial pressure was +2 (SD11) mm Hg for systolic, -4(8) mm Hg for mean, and -3(7) mm Hg for diastolic pressure. Compared to these control differences, the average finger minus intra-arterial pressure differences for mean and diastolic pressures during the three orthostatic manoeuvres were always within the range -6 to +6 mm Hg. The average systolic deviations were larger, ranging from -10 to +11 mm Hg. Despite these differences the characteristic changes in intra-arterial pressure during the initial phase (first 30 s after change of posture), as well as during the early steady state phase (1-2 min after the change of posture) were well reflected by finger pressure measurements in all subjects. For the assessment of the continuous blood pressure responses to orthostatic stress similar information can be obtained with non-invasive Finapres blood pressure recordings as with invasive recordings.

Health equipment bulletin news

These evaluations of electromedical equipment will soon focus on single items only rather than covering batches of items within a category. This will allow critical evaluations to reach the consumer more quickly after the introduction of the product. Summaries of the reports will still be collected, however, and will appear as a ‘review issue’ produced annually for the major product categories. This change-over from batch to single reports will take place over the next year. In the meantime, issue 189 (March 1989) contains full reports on six non-invasive blood pressure recorders and issue 190 (March 1989) reports on six ECG recorders.

Seasonal influences on blood pressure in high normal to mild hypertensive range.

To investigate the seasonal influences on various arterial blood pressure measurements, 22 subjects in the high normal to mild hypertensive range were examined twice following the same protocol. In one group (13 subjects), measurements were first done in warm conditions and repeated 5-7 months later in cold conditions; in the second group (nine subjects) a reverse sequence was followed. Blood pressure was measured under casual conditions during a hand grip exercise test, mental arithmetic test, and submaximal multistage bicycle exercise test; during the following 24 hours, blood pressure was measured serially with a noninvasive ambulatory blood pressure recorder. Daily outdoor maximum and indoor laboratory temperatures were also obtained. In the cold season, significantly higher values (on the average by 5-10 mm Hg, p less than 0.01) were obtained in both groups for mean diastolic daytime blood pressure. For other measurements, a trend toward higher values in the cold season was observed in both groups, although statistical significance was not obtained in all instances. For nighttime measurements, irrespective of the seasonal sequence, lower values were observed in the second session. Significant correlations were found between the differences in the average daytime ambulatory blood pressures and the corresponding changes of daily maximum outdoor temperatures after 5-7 months. These observations indicate that arterial blood pressure may be strongly influenced by environmental temperature. This phenomenon should be taken into account both in the evaluation of the individual hypertensive patients and in the design and analysis of studies on arterial hypertension, especially when ambulatory blood pressure techniques are employed.

Pressor effects from daily events and laboratory complex stimuli relating personality factors.

Our preliminary research has attempted to establish a series of methods to study the complex interactions occurring between pressor reactivity and personality profile. Ten untreated mild hypertensives (age 42.9 +/- 8) without damaged target organs were recruited from an outpatient hypertension center along with an equal number of normotensive volunteers (age 38.2 +/- 8.1). We performed a sequence of stressor types under laboratory conditions (sensory perceptual activities, psychomotor responses, and cognitive behavior) following an order ranging from inferior levels to superior levels of systemic integration. The subjects also underwent a 24-h automatic noninvasive blood pressure recording which took into account the situational reactivity. They filled in MMPI and STAI questionnaires before and after the stressor batteries. Only the sensory-perceptual test (Stroop color test modified), the arithmetic test, and the psychomotor test provoked a significant increase in blood pressure and, in the latter test, also a significant increase of the heart rate. The test batteries' mean differences were not significant between the two groups. Similarly, the answers to the trait-anxiety questionnaires did not allow us to make a substantial division between normotensive and hypertensive subjects. On the contrary, the situational anxiety questionnaires showed a significant difference in the score reading preceding and following a task performed by the hypertensive subjects. We observed significant differences for both systolic and diastolic 24-h blood pressure data in transition from a working situation to the sleeping period. However, there was not a significant difference in hypertensive blood pressure readings recorded during work and at home.(ABSTRACT TRUNCATED AT 250 WORDS)

What is the role of ambulatory blood pressure monitoring in the management of hypertensive patients?

Noninvasive ambulatory blood pressure (BP) recording is now clinically available for the evaluation of hypertensive patients. It is well known that pressures measured in the office or clinic are unreliable and that repeated measurements are better at predicting outcome than are single measurements. Several studies have compared the correlation between target organ damage and different measures of BP, and in every instance ambulatory BP measurements have given better correlations than clinic readings. In one prospective study the ambulatory BP readings were more predictive of BP-related morbidity than were clinic readings. Data are now being obtained that will establish normal ranges of BP during ambulatory monitoring, against which values from patients being evaluated for hypertension can be compared. It is concluded that ambulatory BP monitoring is of clinical value for the evaluation of patients with mild hypertension.