Evaluation of cholesterol lowering treatment of patients with familial hypercholesterolemia: a large cross-sectional study in The Netherlands.

BACKGROUND: Heterozygous familial hypercholesterolemia (heFH) is a common autosomal dominant hereditary disorder caused by mutations in the LDL-receptor gene that lead to elevated plasma levels of low-density lipoprotein-cholesterol (LDL-c). Robust lowering of LDL-c levels is essential for risk reduction of premature cardiovascular diseases and early death. European and Dutch guidelines recommend to treat LDL-c to plasma levels <2.5mmol/l. In the present study we evaluated the treatment of heFH patients in The Netherlands. METHODS: A cross-sectional study was conducted in outpatient lipid clinics of three Academic Centers and two regional hospitals. Patient records of known heFH patients were retrieved and data were reviewed on the use of lipid-lowering medication, plasma lipids and lipoproteins, safety laboratory results and reasons for not achieving treatment goals. RESULTS: The data of 1249 patients with heFH were available. Nearly all patients (96%) were on statin treatment. The treatment goal for LDL-c <2.5mmol/l was achieved in 261 (21%) patients. Among those who did not reach LDL-c goals, 261 (27%) were on combination therapy of maximum statin dose and ezetimibe. Main reason (32%) why patients did not use maximum therapy despite an LDL-c >or=2.5mmol/l, was acceptance of a higher target LDL-c level by the treating physician. An alternative treatment goal of >50% LDL-c reduction, as recommended in the NICE guidelines, was achieved in 47% of patients with an LDL-c >or=2.5mmol/l and not using maximum therapy. CONCLUSION: Only a small proportion of patients with heFH reaches the LDL-c treatment target of <2.5mmol/l. These results emphasize the need for better monitoring, better utilization of available medication and for new treatment options in heFH to further decrease LDL-c levels.

Estimation of beat-to-beat changes in stroke volume from arterial pressure: a comparison of two pressure wave analysis techniques during head-up tilt testing in young, healthy men.

OBJECTIVE: The aim of this study was to compare beat-to-beat changes in stroke volume (SV) estimated by two different pressure wave analysis techniques during orthostatic stress testing: pulse contour analysis and Modelflow, i.e., simulation of a three-element model of aortic input impedance. METHODS: A reduction in SV was introduced in eight healthy young men (mean age, 25; range, 19-32 y) by a 30-minute head-up tilt maneuver. Intrabrachial and noninvasive finger pressure were monitored simultaneously. Beat-to-beat changes in SV were estimated from intrabrachial pressure by pulse contour analysis and Modelflow. In addition, the relative differences in Modelflow SV obtained from intrabrachial pressure and noninvasive finger pressure were assessed. RESULTS: Beat-to-beat changes in Modelflow SV from intrabrachial pressure were comparable with pulse contour measures. The relative difference between the two methods amounted to 0.1+/-1% (mean +/- SEM) and was not dependent on the duration of tilt. The difference between Modelflow applied to intrabrachial pressure and finger pressure amounted to -2.7+/-1.3% (p = 0.04). This difference was not dependent on the duration of tilt or level of arterial pressure. CONCLUSIONS: Based on different mathematical models of the human arterial system, pulse contour and Modelflow compute similar changes in SV from intrabrachial pressure during orthostatic stress testing in young healthy men. The magnitude of the difference in SV derived from intrabrachial and finger pressure may vary among subjects; Modelflow SV from noninvasive finger pressure tracks fast and brisk changes in SV derived from intrabrachial pressure.

Broad-band spectral analysis of 24 h continuous finger blood pressure: comparison with intra-arterial recordings.

The present study compares the spectral characteristics of 24-h blood pressure variability estimated invasively at the brachial artery level with those estimated by measurement of blood pressure at the finger artery using the non-invasive Portapres device. Broad-band spectra (from 3x10(-5) to 0.5 Hz) were derived from both finger and intra-brachial pressures recorded simultaneously for 24 h in eight normotensive and twelve hypertensive ambulant subjects. At frequencies lower than 0.07 Hz, higher spectral estimates were obtained by Portapres than by intra-brachial measurements. The maximum overestimation occurred in systolic pressure at around 10(-2) Hz, where the amplitude of the oscillations was two times greater when measured by Portapres. A less pronounced overestimation was found for diastolic pressures. The maximum overestimation was greater during daytime than during night-time. At around 0.1 Hz, invasive and non-invasive spectra were similar. At the respiratory frequencies (0.15-0.50 Hz), the power spectra were overestimated by Portapres during daytime, and underestimated at night. These results provide reference information for the correct interpretation of Portapres data in the estimation of 24-h blood pressure spectral power.

Fifteen years experience with finger arterial pressure monitoring: assessment of the technology.

We review the Finapres technology, embodied in several TNO-prototypes and in the Ohmeda 2300 and 2300e Finapres NIBP. Finapres is an acronym for FINger Arterial PRESsure, the device delivers a continuous finger arterial pressure waveform. Many papers report on the accuracy of the device in comparison with intra-arterial or with noninvasive but intermittent blood pressure measurements. We compiled the results of 43 such papers and found systolic, diastolic and mean accuracies, in this order, ranging from -48 to 30 mmHg, from -20 to 18 mmHg, and from -13 to 25 mmHg. Weighted for the number of subjects included pooled accuracies were -0.8 (SD 11.9), -1.6 (8.3) and -1.6 (7.6) mmHg respectively. Subdividing the pooled group according to criteria such as reference blood pressure, place of application, and prototype or commercial device we found no significant differences in mean differences or SD. Measurement at the finger allows uninterrupted recordings of long duration. The transmission of the pressure pulse along the arm arteries, however, causes distortion of the pulse waveform and depression of the mean blood pressure level. These effects can be reduced by appropriate filtering, and upper arm 'return-to-flow' calibration to bring accuracy and precision within AAMI limits. For the assessment of beat-to-beat changes in blood pressure and assessment of blood pressure variability Finapres proved a reliable alternative for invasive measurements when mean and diastolic pressures are concerned. Differences in systolic pressure are larger and reach statistical significance but are not of clinical relevance. Finger arteries are affected by contraction and dilatation in relation to psychological and physical (heat, cold, blood loss, orthostasis) stress. Effects of these phenomena are reduced by the built-in Physiocal algorithm. However, full smooth muscle contraction should be avoided in the awake patient by comforting the patient, and covering the hand. Arterial state can be monitored by observing the behaviour of the Physiocal algorithm. We conclude that Finapres accuracy and precision usually suffice for reliable tracking of changes in blood pressure. Diagnostic accuracy may be achieved with future application of corrective measures.

Estimation of blood pressure variability from 24-hour ambulatory finger blood pressure.

Portapres is a noninvasive, beat-to-beat finger blood pressure (BP) monitor that has been shown to accurately estimate 24-hour intra-arterial BP at normal and high BPs. However, no information is available on the ability of this device to accurately track ambulatory BP variability. In 20 ambulatory normotensive and hypertensive subjects, we measured 24-hour BP by Portapres and through a brachial artery catheter. BP and pulse interval variabilities were quantified by (1) the SDs of the mean values (overall variability) and (2) spectral power, computed either by fast Fourier transform and autoregressive modeling of segments of 120-second duration for spectral components from 0.025 to 0.50 Hz or in a very low frequency range (between 0.00003 and 0.01 Hz) by broadband spectral analysis. The 24-hour SD of systolic BP obtained from Portapres (24+/-2 mm Hg) was greater than that obtained intra-arterially (17+/-1 mm Hg, P<0.01), but the overestimation was less evident for diastolic (3+/-1 mm Hg, P<0.01) and mean (3+/-1 mm Hg, P<0.01) BP. The BP spectral power <0.15 Hz was also overestimated by Portapres more for systolic than for diastolic and mean BPs; similar findings were obtained by the fast Fourier transform, the autoregressive approach, and focusing on the broadband spectral analysis. BP spectral power >0.15 Hz obtained by the Portapres was similar during the day but lower during the night when compared with those obtained by intra-arterial recordings (P<0.01). No differences were observed between Portapres and intra-arterial recordings for any estimation of pulse interval variabilities. The overestimation of BP variability by Portapres remained constant over virtually the entire 24-hour recording period. Thus, although clinical studies are still needed to demonstrate the clinical relevance of finger BP variability, our study shows that Portapres can be used with little error to estimate 24-hour BP variabilities if diastolic and mean BPs are used. For systolic BP, the greater error can be minimized by using correction factors.

The Valsalva manoeuvre as a cardiovascular reflex test in healthy children and teenagers.

The objective of this study was to determine whether the Valsalva manoeuvre is applicable as a test for neurocardiovascular control in healthy children and teenagers. Sixty-eight 6- to 16-year-old children and teenagers performed two Valsalva manoeuvres in the sitting position. They were instructed to maintain airway pressure (strain) for 15 s at 30 mmHg in the first and at 40 mmHg in the second manoeuvre. Finger arterial pressure and heart rate were monitored continuously. In three of the 68 subjects it was not possible to obtain a reliable blood pressure recording due to movements of the finger and/or hand. Only 10 subjects were able to reach a strain of 30 mmHg and to maintain this strain constant during 15 s; in the others the level or the duration of the strain varied substantially. Nine subjects kept strain at 40 mmHg during 15 s. With a Valsalva manoeuvre of 30 mmHg, control values of blood pressure and heart rate in the last 5 s prior to the manoeuvre increased in 11 subjects. Notwithstanding the large range in straining (15-55 mmHg), on visual inspection blood pressure and heart rate responses known from studies in adults could be recognized in 57 of the 65 subjects. In the other eight subjects atypical heart rate responses were observed. Forty-four of the 65 subjects could perform a Valsalva manoeuvre with a higher airway pressure compared to the first manoeuvre: range 35-55 mmHg. The higher airway pressure resulted in more pronounced blood pressure and heart rate responses. There was no correlation between age and gender versus airway pressure. It was concluded that the Valsalva manoeuvre generated blood pressure responses as found in adults. Heart rate responses were sometimes atypical, and needed underlying blood pressure measurement for full interpretation. For quantitative analysis the test was hampered by the inability of the majority of our young subjects to produce the exact strain during the 15-s period. Qualitatively, however, the Valsalva manoeuvre seems applicable as a cardiovascular reflex test to assess neurocardiovascular control in children and teenagers.

Finger arterial versus intrabrachial pressure and continuous cardiac output during head-up tilt testing in healthy subjects.

1. The aims of this study were to determine the clinical feasibility of continuous, non-invasive Finapres recordings as a replacement for intrabrachial pressure during a 30 min head-up tilt, and the reliability of continuous cardiac output computation by pulse contour analysis from the finger arterial versus the brachial waveform. 2. In eight healthy subjects a 30 min 70 degrees passive head-up tilt was performed. Finger arterial (FINAP) and intrabrachial (IAP) pressures were measured simultaneously. Beat-to-beat changes in stroke volume were computed using a pulse contour algorithm. 3. Accuracy (the group-averaged FINAP-IAP difference) and precision (the SD of the difference) of Finapres measurements were 4 and 9 mmHg for systolic blood pressure, -5 and 9 mmHg for mean blood pressure and -5 and 9mmHg for diastolic blood pressure. 4. The time course of the FINAP-IAP differences during head-up tilt showed a linear trend (P < 0.001 for all pressure levels). Averaged for the group, the difference increased 7 mmHg for mean blood pressure. The difference in stroke volume computed from FINAP and IAP was 0.3 +/- 5% (mean +/- SD), and independent of the duration of the tilt (P > 0.05). This difference did not change at low blood pressure levels (0.5 +/- 6%). 5. The qualitative performance of the Finapres allows it to be used in the clinical setting as a monitor of sudden changes in blood pressure induced by a 30 min head-up tilt. Relative changes in stroke volume, as obtained by pulse contour analysis of the finger arterial waveform, closely follow intrabrachial values during long-duration head-up tilt and associated arterial hypotension.

Finapres tracking of systolic pressure and baroreflex sensitivity improved by waveform filtering.

OBJECTIVE: Arterial pressure waveforms distort between brachial and finger arteries, causing differences mainly in systolic pressure. Distortion, reportedly, can be removed by applying a waveform filter to the finger pressure. DESIGN: We analysed the data from two studies that detected discrepancies in systolic tracking between Finapres and brachial pressures. The first set comprised waveforms of seven volunteers during incremental bicycle exercise to exhaustion and the second set comprised waveforms of eight volunteers during increasing phenylephrine infusion. METHODS: We applied the filter and compared 1 min averaged unfiltered and waveform-filtered finger and brachial pressures. RESULTS: During exercise, finger systolic pressure overestimated brachial increasingly, from 7(SD 10) mmHg at rest to 27(17) mmHg at maximal exertion. Differences were reduced by waveform filtering from 3 (SD 9)mmHg at rest to 1 (SD 15)mmHg at maximal exertion. During phenylephrine infusion finger systolic pressure overestimated brachial pressure, but the magnitude of the overestimate decreased from 14 (SD 15)mmHg at baseline to -1(SD 16)mmHg at maximal rate. After waveform filtering overestimation was an almost constant 6(SD 11)mmHg. Median baroreflex sensitivities from brachial, unfiltered and waveform-filtered finger pressure were 5.8, 7.5 and 5.3 ms/mmHg and correlation increased after filtering. The results indicate improved systolic pressure tracking after waveform filtering. CONCLUSIONS: Finger pressure distortion follows a general pattern correctable by waveform filtering. Waveform filtering allows a 'brachial' view to be obtained from Finapres data.

Automated blood pressure measurement during ergometric stress testing: possibilities of Finapres.

BACKGROUND: The accurate recording of the blood pressure response to ergometry is of increasing interest in clinical practice, yet its measurement is susceptible to considerable error. We searched the literature for studies that describe devices designed for automated measurement of indirect blood pressure during dynamic exercise. As a possible alternative we studied in seven normotensive subjects noninvasive continuous finger arterial and simultaneously recorded intrabrachial pressure before, during and after maximal bicycle ergometry to 220-340 watts. RESULTS: The automated devices designed to pick up the Korotkoff sounds, even with support of R-wave EKG detection, amplification of K-sounds and/or implementation of microprocessor technology did not achieve the accuracy of conventional Riva-Rocci-Korotkoff sphygmomanometry. At maximal exercise brachial systolic, diastolic and mean responses were 67 +/- 20, 13 +/- 7 mm Hg and 35 +/- 13 respectively. In the finger systolic pressure increased significantly more (85 +/- 29 mm Hg, p < 0.05) but comparable responses were found for diastolic and mean pressure (18 +/- 12 mm Hg and 36 +/- 18). CONCLUSIONS: Automated blood pressure devices are not an improvement over conventional auscultatory measurement. Finger blood pressure can be measured even at maximal exercise, with a reliable continuous measurement of intrabrachial responses for mean and diastolic pressures.

Circadian profile of systemic hemodynamics.

We determined the continuous 24-hour profile of mean arterial pressure, heart rate, stroke volume, cardiac output, and total peripheral resistance in eight healthy ambulatory volunteers. Beat-to-beat intra-arterial blood pressure was recorded with the Oxford system; subjects were ambulant during daytime and slept at night. Beat-to-beat stroke volume was determined by the pulse contour method from the arterial pulse wave. During the nighttime, compared with the daytime average, there was a decrease in blood pressure (9 mm Hg), heart rate (18 beats per minute), and cardiac output (29%); stroke volume showed a small decrease (7%), and total peripheral resistance increased unexpectedly by 22%. When subjects arose in the morning a steep increase in cardiac output and decrease in total peripheral resistance were found. Comparable changes were seen during a period of supine resting in the afternoon, whereas physical exercise caused opposite changes in hemodynamics. This pattern was observed in all subjects. We conclude that the circadian pattern of cardiac output and total peripheral resistance originates from the day-night pattern in physical activity: during the nighttime, blood flow to the skeletal muscles is decreased through local autoregulation, which increases total peripheral resistance and decreases cardiac output compared with the daytime.

Effects of aging on blood pressure variability in resting conditions.

The objective of this study was to determine the effect of aging on beat-to-beat blood pressure and pulse interval variability in resting conditions and to determine the effect of aging on the sympathetic and vagal influence on the cardiovascular system by power spectral analysis of blood pressure and pulse interval. We studied three groups of healthy, normotensive subjects: young (10 to 15 years, n = 16), adult (20 to 40 years, n = 16), and elderly (70 to 90 years, n = 25). Beat-to-beat blood pressure was measured by Finapres during 20 minutes supine and 10 minutes standing. Overall systolic and diastolic blood pressures and pulse interval variability were determined as SD and as coefficient of variation. Also, relative powers of the mid-frequency (0.08 to 0.12 Hz) and high-frequency bands (0.15 to 0.40 Hz) were determined by spectral analysis. In these subjects no differences in blood pressure variability (either as SD or coefficient of variation) were found between age groups, except for the coefficient of variation of standing diastolic blood pressure, which decreased with aging. Pulse interval variability decreased with aging. Power of the mid-frequency band of systolic and diastolic blood pressures was markedly decreased in the elderly, especially in the standing position. Power of the high-frequency band of pulse interval was also decreased in the elderly. Baroreflex sensitivity calculated by fast Fourier transformation spectral analysis was decreased in the elderly subjects compared with the younger groups. In conclusion, we found no change in the overall variability of blood pressure with aging. Mid-frequency spectral power of blood pressure and mid- and high-frequency spectral powers of pulse interval variability were decreased in the elderly. These results suggest that aging does not merely influence the magnitude of blood pressure and pulse interval variability but causes a complex rearrangement of the variability pattern by changes in neurocardiovascular regulation.

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.

Effects of graded vasoconstriction upon the measurement of finger arterial pressure.

OBJECTIVE: To assess the effects of incremental phenylephrine infusion rates and subsequent graded vasoconstriction upon the performance of the Ohmeda Finapres. DESIGN: Blood pressure in eight hypertensive patients in the finger and the brachial artery was recorded simultaneously. Systolic blood pressure (SBP), diastolic blood pressure (DPB) and mean arterial pressure (MAP) were compared as well as additional waveform characteristics like the pressure at moment of the dicrotic notch and calculation of the pulsatile-systolic areas. RESULTS: Before phenylephrine infusion SBP and DBP were higher in the finger. At maximal infusion (1.6 micrograms/kg/min) the increase in brachial SBP was significantly underestimated by Finapres. Thus, the computed sensitivities of baroreflex control for SBP differed significantly between the two measurements. Under control conditions, the shape of the finger waveform differed from the brachial-artery waveform in terms of: (1) a more peaked appearance; (2) a dicrotic notch (Pnotch) which is located at a lower percentage of pulse pressure; and (3) a larger pulsatile-systolic area. At maximal infusion rates finger Pnotch increased whilst intrabrachial Pnotch did not. In contrast, the brachial and finger pulsatile-systolic areas changed fully in parallel. CONCLUSIONS: Phenylephrine infusion caused a significant, and clinically important, underestimation of the increase in brachial SBP when assessed by Finapres, whereas MAP and DBP and pulsatile-systolic area track intra-arterial pressure reliably.

The reliability of noninvasive continuous finger blood pressure measurement in patients with both hypertension and vascular disease.

In conditions of compromised peripheral circulation, the measurement of noninvasive continuous finger blood pressure with the Finapres device may show reduced accuracy. We therefore compared Finapres blood pressure (FINAP) with intrabrachial blood pressure (IAP) responses to the Valsalva maneuver and arising in 12 patients in whom the peripheral circulation was expected to be compromised due to the combination of therapy-resistant hypertension and vascular disease. During a 30 sec control period the FINAP--IAP differences were -15.7 +/- 18.8 mm Hg (mean +/- SD) for systolic, -20.1 +/- 15.7 mm Hg for mean, and -13.5 +/- 15.7 mm Hg for diastolic pressure. During the Valsalva maneuver and prolonged standing Finapres reproduced the essential characteristics of the changes in IAP in all patients. However, in individual patients, the magnitude of the intraarterial blood pressure response was sometimes over- or underestimated by Finapres. Nevertheless, the group averaged blood pressure, in particular mean and diastolic pressure, response to cardiovascular stimuli, was well reproduced by Finapres. In conclusion, as expected physiologically, individual Finapres measurements in patients with vascular disease do not always equal the intrabrachial pressure and should thus be evaluated with care. However, the Finapres device can be used with sufficient confidence to study the group averaged responses to cardiovascular stimuli in these patients.

Disparities in circulatory adjustment to standing between young and elderly subjects explained by pulse contour analysis.

1. The circulatory adjustment to standing was investigated in two age groups. Young subjects consisted of 20 healthy 10-14-year-old girls and boys. Elderly subjects consisted of 40 70-86-year-old healthy and active females and males. Continuous responses of blood pressure and heart rate were recorded by Finapres. A pulse contour algorithm applied to the finger arterial pressure waveform was used to assess stroke volume responses. 2. During the first 30s (initial phase), an almost identical drop in mean blood pressure was found in both age groups (young, 16 +/- 10 mmHg; old, 17 +/- 10 mmHg), but the initial heart rate increase was attenuated in the elderly subjects (young, 29 +/- 7 beats/min; old, 17 +/- 7 beats/min). 3. During the period from 30 s to 10 min of standing, mean blood pressure increased from 96 +/- 12 to 106 +/- 12 mmHg in the elderly subjects compared with almost no change in the young subjects (from 82 +/- 8 to 84 +/- 7 mmHg). In the elderly subjects a progressive increase in total peripheral resistance (from 114 +/- 14% to 146 +/- 29%) was found, compared with an initial rapid increase in total peripheral resistance (126 +/- 18% after 30 s) with no further change during prolonged standing (124 +/- 17% after 10 min) in the young subjects. In this age group the decrease in stroke volume and the increase in heart rate after 10 min of standing were large (young, -37 +/- 11% and 27 +/- 11 beats/min; old, -31 +/- 9% and 7 +/- 6 beats/min, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Postural dizziness and transient hypotension in two healthy teenagers.

Neurocardiovascular control during postural change was investigated in two teenage females with complaints of dizziness almost immediately on standing up. Blood pressure and heart rate were monitored continuously with a Finapres device. On standing there was a brief but marked fall in blood pressure between 5-10 s after the onset of the manoeuvre. The maximum fall in systolic and diastolic blood pressure was 65 mmHg and 40 mmHg respectively in the first subject, and 58 mmHg and 29 mmHg respectively in the second subject. In both, postural tachycardia was present after 1-2 min of standing with heart rate increasing by up to 39 beats/min in the first subject and 60 beats/min in the second subject. On a follow-up examination 3 years later these changes had disappeared in the first subject while they persisted in the second subject, when she was studied two years later. We conclude that in these patients initial postural dizziness is related to an excessive fall in blood pressure upon standing.

Circulatory adaptation to orthostatic stress in healthy 10-14-year-old children investigated in a general practice.

1. The magnitude and time course of circulatory adaptation to active standing were investigated in healthy premenarchic girls and boys (n = 24; 10-14 years old) by non-invasive measurement of heart rate and continuous finger blood pressure (Finapres). 2. Four subjects (two girls, two boys) showed presyncopal symptoms after 4-9 min of free standing. 3. In the 20 non-fainting subjects, changes in blood pressure and heart rate upon standing did not differ between girls (n = 10) and boys (n = 10). In the initial phase of standing (first 30 s) systolic and diastolic blood pressures dropped by 22 +/- 14 (mean +/- SD) and 16 +/- 7 mmHg, respectively, at 8 +/- 2 s. Blood pressure subsequently recovered and showed an overshoot in all subjects. The transient drop in blood pressure was accompanied by an increase in heart rate of 40 +/- 7 beats/min. These characteristic transient changes were not observed with passive head-up tilt. During the early steady-state phase (2 min), systolic blood pressure was similar to the supine value and diastolic blood pressure rose by 11 +/- 5 mmHg. Heart rate increased by 25 +/- 11 beats/min. In six of the subjects (three girls, three boys) the increase in heart rate exceeded 30 beats/min (postural tachycardia). Little further changes were observed during prolonged (10 min) standing.(ABSTRACT TRUNCATED AT 250 WORDS)

Continuous finger arterial pressure: utility in the cardiovascular laboratory.

The clinical utility for autonomic research purposes of the Finapres, a device for measuring finger arterial pressure continuously and noninvasively, was assessed by estimating its accuracy, precision and within-subject variability in 48 subjects, aged 18-65 years, in comparison with intraarterial brachial blood pressure. At differences of -3.5 +/- 12, -8.0 +/- 8 and -4.4 +/- 8 mmHg from simultaneous intrabrachial systolic, mean and diastolic pressure, the Finapres meets the Association for the Advancement of Medical Instruments (AAMI) accuracy requirements for systolic and diastolic, but not for mean pressure. The precision requirements were nearly met for mean and diastolic, but not for systolic pressure. These results compare to those of others under widely varying circumstances in anaesthetized and awake subjects, and are comparable to those published for the auscultatory technique. The within-subject precision of Finapres is high; the 95% confidence intervals are 3.4-4.5 mmHg for systolic, 1.5-2.0 mmHg for mean and 1.7-2.2 mmHg for diastolic. This makes the Finapres suitable for tracking changes in blood pressure. Four case studies are provided as examples of the value of the Finapres in the clinical laboratory.

Singing-induced hypotension: a complication of a high spinal cord lesion.

Cardiovascular autonomic control was studied in a patient with an incomplete high spinal cord lesion who presented with the symptoms of severe dizziness during debating and singing but not during orthostasis. The marked falls in blood pressure upon singing and orthostasis (45 degrees passive head-up tilt) were comparable in magnitude but different in time course. The fall in blood pressure upon graded Valsalva manoeuvres, however, was comparable to singing in magnitude and time course; similarly, 20 and 30 mmHg strain evoked complaints of dizziness. These differential circulatory responses upon orthostasis versus singing and Valsalva in tetraplegic patients have not been described before. We suggest that rapidly developing hypotension such as that induced by a moderate Valsalva strain represents the instantaneous mechanical effects of a raised intrathoracic pressure with lack of abdominal compression on the cardiovascular system when baroreflex vasomotor modulation is disrupted.

Initial blood pressure fall on stand up and exercise explained by changes in total peripheral resistance.

To elucidate the underlying mechanisms of the initial fall in blood pressure on standing upright from the supine position, we measured the beat-to-beat changes in intra-arterial pressure in eight healthy male subjects in response to standing. Changes in stroke volume, cardiac output, and total peripheral resistance were computed from the pressure waveform using a pulse contour method. To determine possible mechanisms for the changes observed on standing, similar measures were made on passive tilting and a brief (3-s) bout of cycle exercise. Standing elicited a transient 25% (23-mmHg) fall in mean blood pressure as a result of a 36% fall in total peripheral resistance. Head-up tilt elicited a gradual change in haemodynamic parameters, which reached plateau levels in 20-30 s. Cycling elicited a transient 17% (18-mmHg) fall in blood pressure and a 41% fall in total peripheral resistance. In addition, we measured right atrial and esophageal pressures in two subjects on standing and cycling and found a 10- to 15-mmHg rise in right atrial pressure without a corresponding change in esophageal pressure. This points to the cardiopulmonary reflex as the primary effector of peripheral vasodilation, but we cannot exclude the possibility that 1) local metabolic vasodilation and 2) central command-mediated cholinergic vasodilation contributed to the fall in vascular resistance.