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1.  Evaluation of oscillometric and Doppler ultrasonic methods of indirect blood pressure estimation in conscious dogs 
Abstract
To assess the accuracy and precision of indirect measurements of systemic arterial blood pressure (BP), results obtained with an oscillometric device (BPo) and a Doppler ultrasonic device (BPud) were compared with those obtained by direct radiotelemetry (BPrt) in 12 conscious beagles. The correlation between indirectly obtained and directly measured values for BP parameters ranged widely for the different indirect methods and sites of cuff placement, with R2 between 0.001 and 0.901. Both indirect methods underestimated all BP parameters, the degree of underestimation increasing at higher values for the BP. The highest correlation occurred when estimates were the average of 5 values consecutively obtained with the oscillometric device and cuff placement at the coccygeal artery (R2 = 0.854 for mean BPo, 0.886 for systolic BPo, and 0.901 for diastolic BPo; P < 0.0001 for all parameters) or with the ultrasonic Doppler device at the metatarsal arteries (R2 = 0.810 for systolic BPud; P < 0.0001). Multiple consecutively obtained values are advised, as this approach improves the reliability of indirect BP measurements. The strong correlation between directly measured values and estimates derived as the average of 5 consecutive indirectly obtained values indicates that the latter approach provides a useful estimate of BP in conscious dogs and is likely to be useful in monitoring disease progress and treatment in dogs with abnormal BP.
PMCID: PMC1477936  PMID: 16850944
2.  Evaluation of the accuracy of non-invasive automatic blood pressure monitors. 
Anesthesia Progress  1990;37(5):244-247.
Non-invasive automatic blood pressure monitors (BP-103N, DINAMAP 845XT, Finapres 2300) were compared with the auscultatory method. The blood pressure readings given by the oscillometric method (BP-103N, DINAMAP 845XT) were accurate and reproducible. Agreement with the auscultatory method was especially good for systolic pressure. For diastolic pressure readings, there was less agreement with the results of the auscultatory method. The finger arterial pressure method (Finapres 2300) occasionally displayed greater variability than the devices using the oscillometric method.
PMCID: PMC2148609  PMID: 2096748
3.  Ankle blood pressure measured by automatic oscillotonometry: a comparison with Doppler pressure measurements. 
Oscillotonometry using Dinamap machine was investigated for the measurement of ankle and brachial blood pressures in our vascular practice. It was validated by comparison with intra-arterial pressure measured by transducer. Systolic ankle and brachial pressures in 43 patients were compared using the Dinamap and Doppler techniques, and significant correlation was found. Ankle and brachial systolic, diastolic and mean pressures and ankle/brachial pressure indices for all three pressures were measured in a group of 12 normal subjects supine at rest, and after treadmill exercise, and a range of normal values defined. The main limitation of the Dinamap is its failure to measure pressures below 50mmHg. The Dinamap technique is a noninvasive, simple, reproducible and quick method of measuring ankle and brachial pressures in vascular surgical practice.
PMCID: PMC2498533  PMID: 3426091
4.  A comparison of systolic blood pressure measurement obtained using a pulse oximeter, and direct systolic pressure measurement in anesthetized sows. 
Systolic blood pressure measurement obtained with a pulse oximeter has been compared to values obtained by other indirect methods in man. Direct pressure measurement is subject to less error than indirect techniques. This study was designed to compare systolic pressure values obtained using a pulse oximeter, with values obtained by direct arterial pressure measurement. The pulse oximeter waveform was used as an indication of perfusion. A blood pressure cuff was applied proximal to the pulse oximeter probe. The cuff was inflated until the oximeter waveform disappeared, this value was recorded as the systolic pressure at the disappearance of the waveform (SPD). The cuff was inflated to a pressure > 200 mmHg, then gradually deflated until the waveform reappeared, this value was recorded as the systolic pressure at reappearance of the waveform (SPR). The average of the two values, SPD and SPR, was calculated and recorded as SPA. The study was performed in sows (n = 21) undergoing cesarean section under epidural anesthesia and IV sedation. A total of 280 measurements were made of SPD, SPR and SPA. Regression analysis of SPA and direct measurement revealed a correlation coefficient (r) of 0.81. Calculation of mean difference (bias) and standard deviation of the bias (precision) for direct pressure--SPA revealed a value of 1.3 +/- 12.1. When compared with direct measurement, the correlation of this technique was similar to that recorded for other indirect techniques used in small animals. This indicates that this technique would be useful for following systolic pressure trends.(ABSTRACT TRUNCATED AT 250 WORDS)
PMCID: PMC1263681  PMID: 8004540
5.  Blood pressure centiles for Great Britain 
Archives of Disease in Childhood  2006;92(4):298-303.
Objective
To produce representative cross‐sectional blood pressure reference centiles for children and young people living in Great Britain.
Design
Analysis of blood pressure data from seven nationally representative surveys: Health Surveys for England 1995–8, Scottish Health Surveys 1995 and 1998, and National Diet & Nutrition Survey 1997.
Methods
Blood pressure was measured using the Dinamap 8100 with the same protocol throughout. Weight and height were also measured. Data for 11 364 males and 11 537 females aged 4–23 years were included in the analysis, after excluding 0.3% missing or outlying data. Centiles were derived for systolic, diastolic, mean arterial and pulse pressure using the latent moderated structural (LMS) equations method.
Results
Blood pressure in the two sexes was similar in childhood, rising progressively with age and more rapidly during puberty. Systolic pressure rose faster and was appreciably higher in adult men than in adult women. After adjustment for age, blood pressure was related more to weight than height, the effect being stronger for systolic blood pressure. Pulse pressure peaked at 18 years in males and 16 years in females.
Conclusions
These centiles increase our knowledge of blood pressure norms in contemporary British children and young people. High blood pressure for age should be defined as blood pressure above the 98th centile, and high‐normal blood pressure for age as blood pressure between the 91st and 98th centiles. The centiles identify children and young people with increased blood pressure, and will be of benefit to both clinical practice and research.
doi:10.1136/adc.2005.081216
PMCID: PMC2083671  PMID: 16905566
6.  Blood pressure centiles for Great Britain 
Archives of Disease in Childhood  2006;92(4):298-303.
Objective:
To produce representative cross-sectional blood pressure reference centiles for children and young people living in Great Britain.
Design:
Analysis of blood pressure data from seven nationally representative surveys: Health Surveys for England 1995–8, Scottish Health Surveys 1995 and 1998, and National Diet & Nutrition Survey 1997.
Methods:
Blood pressure was measured using the Dinamap 8100 with the same protocol throughout. Weight and height were also measured. Data for 11 364 males and 11 537 females aged 4–23 years were included in the analysis, after excluding 0.3% missing or outlying data. Centiles were derived for systolic, diastolic, mean arterial and pulse pressure using the lambda-mu-sigma (LMS) equations method.
Results:
Blood pressure in the two sexes was similar in childhood, rising progressively with age and more rapidly during puberty. Systolic pressure rose faster and was appreciably higher in adult men than in adult women. After adjustment for age, blood pressure was related more to weight than height, the effect being stronger for systolic blood pressure. Pulse pressure peaked at 18 years in males and 16 years in females.
Conclusions:
These centiles increase our knowledge of blood pressure norms in contemporary British children and young people. High blood pressure for age should be defined as blood pressure above the 98th centile, and high-normal blood pressure for age as blood pressure between the 91st and 98th centiles. The centiles identify children and young people with increased blood pressure, and will be of benefit to both clinical practice and research.
doi:10.1136/adc.2005.081216
PMCID: PMC2083671  PMID: 16905566
7.  Assessment of the accuracy and role of self-recorded blood pressures in the management of hypertension. 
Self-recording of the blood pressure by patients away from hospital or office ("home blood pressure") has been advocated as providing a better estimate of "true" blood pressure. The reliability of home blood-pressure recording has been assessed only by standard indirect methods which themselves are subject to considerable error and variability. The accuracy of self-recorded blood pressures was therefore assessed in 57 patients with essential hypertension by comparison with simultaneous measurements of clinic blood pressures and with intra-arterial blood pressures recorded at home and at hospital. Home systolic blood pressures showed good agreement with clinic and intra-arterial pressures, but home diastolic blood pressures overestimated intra-arterial pressures, as did clinic diastolic pressures. The clinic and home diastolic pressures showed good agreement. There was considerable variability in individual differences comparing the indirect and intra-arterial methods, though the two indirect methods showed much closer agreement. This study suggests that home blood pressures are as accurate as clinic readings but may be recorded more frequently and thus provide more useful information. Neither is likely to approximate the intra-arterial blood pressure.
PMCID: PMC1500674  PMID: 6816333
8.  Oscillometric blood pressure reference values of African full-term neonates in their first days postpartum 
Cardiovascular Journal of Africa  2009;20(6):344-347.
Background
Knowing the normative blood pressure (BP) in a newborn baby is important in order to identify abnormal BP readings. This study was done to determine normative BP values of Nigerian newborns, using the 8100 Dinamap monitor.
Methods
Consecutive full-term neonates delivered in a tertiary centre in Nigeria were recruited for the study. The babies’ systolic (SBP), diastolic (DBP) and mean arterial (MAP) blood pressures were measured within the first four days after birth.
Results
A total of 473 babies were recruited for the study. The mean SBP, DBP and MAP readings on day 1 were 66.8 ± 7.7, 38.5 ± 6.3 and 47.9 ± 6.3 mmHg, respectively. The day 1 SBP of babies > 4 kg were significantly higher than those who weighed < 2.5 and 2.5–4 kg (p = 0.01, p = 0.05), respectively.
Conclusion
This study provided current normative SBP, DBP and MAP values for Nigerian neonates. The BP readings compared with their Caucasian counterparts.
PMCID: PMC3721809  PMID: 20024474
9.  Dinamap fails to detect hypotension in very low birthweight infants. 
Archives of Disease in Childhood  1986;61(8):771-773.
The accuracy of blood pressure measurements obtained from very low birthweight (less than 1500 g) neonates using the Dinamap oscillometric monitor was investigated. Comparisons using umbilical artery measurements showed that the monitor is less reliable in the lower pressure range and specifically that it tends to overestimate pressure in hypotensive infants.
PMCID: PMC1777941  PMID: 3740925
10.  Assessment of Doppler ultrasound to measure systolic and diastolic blood pressures in infants and young children. 
Archives of Disease in Childhood  1975;50(7):542-544.
A recently developed instrument uses the Doppler shift technique to detect vessel wall movement, and it has been suggested that in conjunction with a conventional sphygmomanometer systolic and diastolic blood pressures can be measured. A controlled study was carried out in 20 children recovering from cardiac surgery where direct intra-arterial measurements (one observer) were compared with independent measurements using the Doppler instrument (2 observers). Systolic pressures measured directly and by Doppler technique correlated well and there was no significant difference between intra-arterial and indirect measurements whether the latter were taken by doctors or by nurses. In contrast, direct and indirect diastolic pressure measurements correlated poorly and were significantly overestimated with a mean difference of 6-25 mmHg (range +25 to -10) for doctors, and 4-25 mmHg (range +20 to -10) for nurses. Thus, the instrument adequately measured systolic blood pressure, but in our hands did not give precise measurements for diastolic blood pressure.
PMCID: PMC1544615  PMID: 1167067
11.  Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model 
Background
The oscillometric method of measuring blood pressure with an automated cuff yields valid estimates of mean pressure but questionable estimates of systolic and diastolic pressures. Existing algorithms are sensitive to differences in pulse pressure and artery stiffness. Some are closely guarded trade secrets. Accurate extraction of systolic and diastolic pressures from the envelope of cuff pressure oscillations remains an open problem in biomedical engineering.
Methods
A new analysis of relevant anatomy, physiology and physics reveals the mechanisms underlying the production of cuff pressure oscillations as well as a way to extract systolic and diastolic pressures from the envelope of oscillations in any individual subject. Stiffness characteristics of the compressed artery segment can be extracted from the envelope shape to create an individualized mathematical model. The model is tested with a matrix of possible systolic and diastolic pressure values, and the minimum least squares difference between observed and predicted envelope functions indicates the best fit choices of systolic and diastolic pressure within the test matrix.
Results
The model reproduces realistic cuff pressure oscillations. The regression procedure extracts systolic and diastolic pressures accurately in the face of varying pulse pressure and arterial stiffness. The root mean squared error in extracted systolic and diastolic pressures over a range of challenging test scenarios is 0.3 mmHg.
Conclusions
A new algorithm based on physics and physiology allows accurate extraction of systolic and diastolic pressures from cuff pressure oscillations in a way that can be validated, criticized, and updated in the public domain.
doi:10.1186/1475-925X-11-56
PMCID: PMC3541069  PMID: 22913792
12.  Efficacy of preanesthetic intramuscular administration of ephedrine for prevention of anesthesia-induced hypotension in cats and dogs 
The Canadian Veterinary Journal  2009;50(2):179-184.
To determine if the preanesthetic administration of ephedrine would prevent anesthesia-induced hypotension in dogs and cats, 10 cats were anesthetized with acepromazine, butorphanol, ketamine, and isoflurane, and 8 dogs were anesthetized with acepromazine, morphine, propofol, and halothane. Cats received ephedrine or saline 10 minutes after premedication. Dogs received ephedrine or saline at the time of premedication. Systolic arterial blood pressure, respiratory rate, heart rate, end-tidal CO2, O2 saturation, cardiac rhythm, and rectal temperature were recorded.
The systolic arterial pressure in cats receiving saline was significantly lower than baseline at 10 minutes after premedication, and systolic arterial pressure was < 80 mmHg for the duration of anesthesia. In cats receiving ephedrine, the systolic arterial pressure was significantly lower than baseline for the duration of anesthesia, but systolic arterial pressure was not < 80 mmHg until 25 min after induction. In dogs, systolic arterial pressure was significantly lower than baseline by 5 and 40 min after pre-medication in dogs receiving saline and ephedrine, respectively. There was no difference in heart rate, respiratory rate, end-tidal CO2, rectal temperature, O2 saturation, or cardiac rhythm among treatment groups. Prophylactic ephedrine delayed, but did not prevent, the onset of hypotension.
PMCID: PMC2629422  PMID: 19412398
13.  Performance of oscillometric blood pressure devices in children in resource-poor settings 
Objective
To compare oscillometric blood pressure devices with mercury sphygmomanometry in children.
Patients and methods
Blood pressure measurements were obtained with a mercury sphygmomanometer and one of two oscillometric devices. Correlations within each device and agreement between the two devices were evaluated.
Results
In children, blood pressure measured by the oscillometric device was poorly correlated and had wide limits of agreements with the sphygmomanometer. Furthermore, the oscillometric devices overestimated systolic blood pressure in children with higher readings.
Conclusion
The applicability of automated blood pressure measuring devices in children has limitations and cannot be recommended.
doi:10.1097/HJR.0b013e3282f738b8
PMCID: PMC2685878  PMID: 18525395
blood pressure determination; developing countries; epidemiologic methods; pediatric; Peru
14.  Use of pulse oximetry for blood pressure measurement after cardiac surgery 
Archives of Disease in Childhood  1998;78(5):457-460.
Blood pressure measurement using pulse oximeter waveform change was compared with an oscillometric measurement and the gold standard, intra-arterial measurement, in children after cardiac surgery. Forty six patients were enrolled and divided into groups according to weight. Simultaneous blood pressure measurements were obtained from the arterial catheter, the oscillometric device, and the pulse oximeter. Pulse oximeter measurements were obtained with a blood pressure cuff proximal to the oximeter probe. The blood pressure measurements from the pulse oximeter method correlated better with intra-arterial measurements than those from the oscillometric device (0.77-0.96 v 0.42-0.83). The absolute differences between the pulse oximeter and intra-arterial measurements were significantly smaller than between the oscillometric and intra-arterial measurements in children less than 15.0 kg. The pulse oximeter waveform change is an accurate and reliable way to measure blood pressure in children non-invasively, and is superior to the oscillometric method for small patients.


PMCID: PMC1717578  PMID: 9659094
15.  Assessment of central haemomodynamics from a brachial cuff in a community setting 
Background
Large artery stiffening and wave reflections are independent predictors of adverse events. To date, their assessment has been limited to specialised techniques and settings. A new, more practical method allowing assessment of central blood pressure from waveforms recorded using a conventional automated oscillometric monitor has recently been validated in laboratory settings. However, the feasibility of this method in a community based setting has not been assessed.
Methods
One-off peripheral and central haemodynamic (systolic and diastolic blood pressure (BP) and pulse pressure) and wave reflection parameters (augmentation pressure (AP) and index, AIx) were obtained from 1,903 volunteers in an Austrian community setting using a transfer-function like method (ARCSolver algorithm) and from waveforms recorded with a regular oscillometric cuff. We assessed these parameters for known differences and associations according to gender and age deciles from <30 years to >80 years in the whole population and a subset with a systolic BP < 140 mmHg.
Results
We obtained 1,793 measures of peripheral and central BP, PP and augmentation parameters. Age and gender associations with central haemodynamic and augmentation parameters reflected those previously established from reference standard non-invasive techniques under specialised settings. Findings were the same for patients with a systolic BP below 140 mmHg (i.e. normotensive). Lower values for AIx in the current study are possibly due to differences in sampling rates, detection frequency and/or averaging procedures and to lower numbers of volunteers in younger age groups.
Conclusion
A novel transfer-function like algorithm, using brachial cuff-based waveform recordings, provides robust and feasible estimates of central systolic pressure and augmentation in community-based settings.
doi:10.1186/1471-2261-12-48
PMCID: PMC3470940  PMID: 22734820
Central pressure; Augmentation; Hypertension; Primary care; Validation
16.  Comparison of invasive and oscillometric blood pressure measurement techniques in anesthetized camelids 
The Canadian Veterinary Journal  2012;53(8):881-885.
This study assessed the accuracy of the oscillometric method for arterial blood pressure (ABP) monitoring in anesthetized camelids. Twenty camelids were anesthetized and systolic ABP (SABP), mean ABP (MABP), and diastolic ABP (DABP) were measured directly and using the oscillometric method. The mean difference between SABP measurements was −9.9 ± 21.9 mmHg with a range of −76 to 54 mmHg, and the 95% limits of agreement (LOA) were −33 to 53 mmHg. The difference between DABP measurements was −1.8 ± 15.6 mmHg with a range of −81 to 36 mmHg, and the 95% LOA were −32 to 29 mmHg. The difference between MABP measurements was −2.9 ± 17.0 mmHg with a range of −81 to 36 mmHg, and the 95% LOA were −30 to 36 mmHg. Accurate ABP monitoring in anesthetized camelids cannot be accomplished using the oscillometric method.
PMCID: PMC3398528  PMID: 23372197
17.  The reliability of the ankle-brachial index in the Atherosclerosis Risk in Communities (ARIC) study and the NHLBI Family Heart Study (FHS) 
Background
A low ankle-brachial index (ABI) is associated with increased risk of coronary heart disease, stroke, and death. Regression model parameter estimates may be biased due to measurement error when the ABI is included as a predictor in regression models, but may be corrected if the reliability coefficient, R, is known. The R for the ABI computed from DINAMAP™ readings of the ankle and brachial SBP is not known.
Methods
A total of 119 participants in both the Atherosclerosis Risk in Communities (ARIC) study and the NHLBI Family Heart Study (FHS) had repeat ABIs taken within 1 year, using a common protocol, automated oscillometric blood pressure measurement devices, and technician pool.
Results
The estimated reliability coefficient for the ankle systolic blood pressure (SBP) was 0.68 (95% CI: 0.57, 0.77) and for the brachial SBP was 0.74 (95% CI: 0.62, 0.83). The reliability for the ABI based on single ankle and arm SBPs was 0.61 (95% CI: 0.50, 0.70) and the reliability of the ABI computed as the ratio of the average of two ankle SBPs to two arm SBPs was estimated from simulated data as 0.70.
Conclusion
These reliability estimates may be used to obtain unbiased parameter estimates if the ABI is included in regression models. Our results suggest the need for repeated measures of the ABI in clinical practice, preferably within visits and also over time, before diagnosing peripheral artery disease and before making therapeutic decisions.
doi:10.1186/1471-2261-6-7
PMCID: PMC1435775  PMID: 16504033
18.  Urethral pressure profile and hemodynamic effects of phenoxybenzamine and prazosin in non-sedated male beagle dogs 
Prazosin is a readily available alpha-adrenergic antagonist that may be useful in the management of functional urethral obstruction in companion animals. This study used urethral pressure profilometry to evaluate the urethral effects of prazosin and phenoxybenzamine in healthy, non-sedated, male Beagle dogs. Heart rate, indirect systolic, diastolic and mean arterial blood pressures were measured, and saline perfusion urethral pressure profilometry was performed at 0, 10, 20, and 40 min following intravenous administration of prazosin (0.025 mg/kg), phenoxybenzamine (0.2 mg/kg), or placebo. Maximal urethral pressure, maximal urethral closure pressure, post peak nadir, and all blood pressure parameters decreased significantly at nearly all treatment intervals following administration of prazosin compared with placebo. Less consistently significant reductions were observed following phenoxybenzamine administration. Maximal decreases in urethral pressure parameters were observed 20 min following the injection of prazosin; maximal blood pressure decreases were evident by 10 min post- injection. In this non-sedated dog model, urethral pressure profilometry was a sensitive method of detecting urethral effects of alpha antagonists. Repeatable reductions in urethral pressure measurements were observed, with prazosin effecting more consistently significant changes than phenoxybenzamine. Significant decreases in systolic, diastolic, and mean arterial blood pressures were seen with prazosin, but not phenoxybenzamine or placebo. Further study of selective alpha-1 antagonists in dogs is needed to determine appropriate oral dosing protocols that will produce maximal urethral effects with minimal hemodynamic effects, and to demonstrate clinical efficacy in dogs with functional urethral obstruction.
PMCID: PMC227024  PMID: 12528826
19.  Relationships between blood pressure and measures of dietary energy intake, physical fitness, and physical activity in Australian children aged 11-12 years. 
STUDY OBJECTIVE--The aim was to examine associations between blood pressure and dietary energy intake, physical activity, and physical fitness in Australian children. DESIGN--The study was a survey of year 7 children attending schools in metropolitan Perth. SETTING--Survey schools were located in suburbs representative of the range of socioeconomic strata in metropolitan Perth. PARTICIPANTS--Data were obtained on 1311 out of 2045 eligible children (64%). The sample included 681 boys and 630 girls. Mean age was 12.0 (SD 0.4) years. MEASUREMENTS AND MAIN RESULTS--Triplicate blood pressure measurements were obtained using a Dinamap oscillometric recorder. Dietary energy intakes were computed from two week day 24 h records. Physical activity was assessed using questionnaires. Physical fitness was measured using a shuttle run test. Additional measurements included weight, height, and skinfold thickness at four sites. A previous observation of an inverse relationship between diastolic blood pressure and dietary energy intake in boys was confirmed. There was evidence of an inverse relationship in girls but not in boys between blood pressure and physical activity. There was little evidence of relationships between blood pressure and physical fitness. CONCLUSIONS--Compared with weight and body mass index, dietary energy intake and the chosen measures of physical activity and physical fitness are poor predictors of blood pressure in the population studied.
PMCID: PMC1059516  PMID: 1583423
20.  Clinical evaluation of Dinamap 845 automated blood pressure recorder. 
British Heart Journal  1980;43(2):202-205.
The Dinamap 845 blood pressure recorder has been evaluated over a wide range of blood pressure by comparison with the Hawksley random zero sphygmomanometer in 32 subjects, six of whom had a cardiac arrhythmia. Group mean radings for systolic and phase 5 diastolic pressure were almost identical but Dinamap diastolic values were on average significantly lower (mean difference 3.4 mmHg) than phase 4 diastolic readings obtained with the Hawksley machine. Correlations between readings with the two instruments were high but the slopes and intercepts of the regression for systolic but not diastolic pressure were significantly different from unity and zero, respectively. The Dinamap is easy to use, portable, and capable of rejecting some motion artefact. Its major disadvantage is that the systolic blood pressure measurement is limited to a maximum of 210 mmHg, a point not made clear in the manufacturer's literature. Nevertheless, the Dinamap 845 is acceptable for blood pressure determinations in subjects who are normotensive or who have mild hypertension.
Images
PMCID: PMC482263  PMID: 7362713
21.  The Dinamap 1846SX automated blood pressure recorder: comparison with the Hawksley random zero sphygmomanometer under field conditions. 
STUDY OBJECTIVE--The aim was to compare the performance of the Dinamap 1846SX automated oscillometric blood pressure recorder with that of the Hawksley random zero sphygmomanometer during use under field study conditions. DESIGN--Two independent within subject measurement comparisons were made, one in adults and one in children, each conducted in three stages over several months while the Dinamap instruments were being used in epidemiological field surveys. SETTING--The studies were done in outpatients clinics (adults) and primary schools (children). PARTICIPANTS--141 adults (20-85 years) and 152 children (5-7 years) took part. MEASUREMENTS AND MAIN RESULTS--In adults a pair of measurements was made with each instrument, the order alternating for consecutive subjects. In children one measurements was made with each instrument, in random order. Measurements with the Dinamap 1846SX were higher than those with the random zero sphygmomanometer both in adults (mean difference 8.1 mm Hg; 95% CI 6.5 to 9.7 mm Hg) and in children (mean difference 8.3 mm Hg; 95% CI 6.9 to 9.7 mm Hg). Diastolic measurements were on average very similar both in adults and in children. The results were consistent at all three stages of both studies. The differences in systolic measurement were independent of blood pressure level. However, the extent of agreement in diastolic pressure depended on the diastolic blood pressure level; in both studies Dinamap diastolic measurements were higher at low diastolic pressures while random zero diastolic measurements were higher at high diastolic pressures. CONCLUSIONS--Systolic measurements made with the Dinamap 1846SX instrument are not directly comparable with those of the Hawksley random zero sphygmomanometer and are unlikely to be comparable with those of earlier Dinamap models. These differences have important implications for clinical practice and for comparisons of blood pressure measurement between epidemiological studies. However, the consistency of measurement by the Dinamap 1846SX over time suggests that the instrument may have a place in standardised blood pressure measurement in the research setting.
PMCID: PMC1059528  PMID: 1583434
22.  Evaluation of vascular wall elasticity of human digital arteries using alternating current-signal photoplethysmography 
Purpose
A simple method of estimating arterial elasticity in the human finger using a volume-oscillometric technique with photoplethysmography was principally studied under the various effects of age, sex, and cold-stress stimulation for testing the capability of using this technique in arterial elasticity analysis.
Methods
Amplitude variations in the alternating current signal of the photoplethysmograph during a continuous change in transmural pressure were analyzed to obtain the blood pressure and the transmural pressure–relative volume difference relationship of the arteries. We first tested the effect of the occluding cuff size on the arterial elasticity analysis in eight subjects (ages 20–45 years) to obtain a suitable cuff size, resulting in the selection of a middle cuff with a 22 mm diameter. Blood pressure and arterial elasticity were measured in six groups of subjects separated into three age-groups of women and men (ages 20–25, 32–45, and over 50 years) for testing the effect of age and sex. Twelve subjects (ages 20–25 years) also had their blood pressure and arterial elasticity measured in three conditions under the influence of the cold-stress stimulation.
Results
Age, sex, and cold-stress stimulation had an impact on mean blood pressure (P < 0.0005, 0.025), whereas pulse pressure and heart rate were statistically unchanged by those factors. Furthermore, an advanced age (over 50 years) was found to induce an increase in relative volume difference values (P < 0.025) and upward shifting of the transmural pressure–relative volume difference relationships, whereas sex, level of mean blood pressure, and cold-stress stimulation had no influence on these forms of the index.
Conclusion
This study showed the usefulness of the relative volume difference as being a mean blood pressure-independent indicator for changes in arterial elasticity.
doi:10.2147/VHRM.S43784
PMCID: PMC3678902  PMID: 23766653
arterial elasticity; volume oscillometry; noninvasive technique; aging process; cold-stress stimulation
23.  Noninvasive Ankle Blood Pressure Measurements by Oscillometry 
Texas Heart Institute Journal  1982;9(3):349-357.
Noninvasive ankle systolic, mean and diastolic pressures were obtained with an oscillometric instrument available commercially. Systolic pressures were also measured at either the posterior tibial or dorsal pedal artery by using the Doppler technique with the ultrasound probe. Ankle pressures were obtained in normal subjects and in patients with peripheral vascular disease, particularly patients with calcified or incompressible vessels or with different posterior tibial and dorsal pedal Doppler pressures. Systolic pressures by oscillometry and by Doppler were equal in normal subjects and in functionally normal limbs of patients. In the presence of mild vascular disease, systolic pressure was decreased and mean and diastolic pressures were within normal limits. Measurements by Doppler and by oscillometry were similar. In patients with moderate disease, the systolic pressure by oscillometry, although decreased, was consistently higher than Dopper pressures, and the mean ankle pressure was decreased. In patients with different posterior tibial and dorsal pedal pressures, the systolic oscillometric pressure was closer to the highest Doppler pressure measured. In contrast, in patients with partially incompressible vessels, the systolic oscillometric pressure was consistently lower than Doppler pressures. The oscillometric instrument available did not detect pressure pulses in patients with severe vascular disease; the weak pressure pulses present can, however, be detected with more sensitive instrumentation.
PMCID: PMC351643  PMID: 15226939
24.  Automatic noninvasive measurement of systolic blood pressure using photoplethysmography 
Background
Automatic measurement of arterial blood pressure is important, but the available commercial automatic blood pressure meters, mostly based on oscillometry, are of low accuracy.
Methods
In this study, we present a cuff-based technique for automatic measurement of systolic blood pressure, based on photoplethysmographic signals measured simultaneously in fingers of both hands. After inflating the pressure cuff to a level above systolic blood pressure in a relatively slow rate, it is slowly deflated. The cuff pressure for which the photoplethysmographic signal reappeared during the deflation of the pressure-cuff was taken as the systolic blood pressure. The algorithm for the detection of the photoplethysmographic signal involves: (1) determination of the time-segments in which the photoplethysmographic signal distal to the cuff is expected to appear, utilizing the photoplethysmographic signal in the free hand, and (2) discrimination between random fluctuations and photoplethysmographic pattern. The detected pulses in the time-segments were identified as photoplethysmographic pulses if they met two criteria, based on the pulse waveform and on the correlation between the signal in each segment and the signal in the two neighboring segments.
Results
Comparison of the photoplethysmographic-based automatic technique to sphygmomanometry, the reference standard, shows that the standard deviation of their differences was 3.7 mmHg. For subjects with systolic blood pressure above 130 mmHg the standard deviation was even lower, 2.9 mmHg. These values are much lower than the 8 mmHg value imposed by AAMI standard for automatic blood pressure meters.
Conclusion
The photoplethysmographic-based technique for automatic measurement of systolic blood pressure, and the algorithm which was presented in this study, seems to be accurate.
doi:10.1186/1475-925X-8-28
PMCID: PMC2772852  PMID: 19857254
25.  Optimising the accuracy of blood pressure monitoring in chronic kidney disease: the utility of BpTRU 
BMC Nephrology  2013;14:218.
Background
Accurate blood pressure monitoring is critical for the management of chronic kidney disease, but changes in management in secondary care clinics may be based on a single blood pressure reading, with a subsequent lack of accuracy. The aim of this study was to evaluate a fully automated sphygmomanometer for optimising the accuracy of blood pressure measurements in the setting of secondary care renal clinics.
Methods
Patients had routine blood pressure measurements with a calibrated DINAMAP PRO400 monitor in a clinical assessment room. Patients then underwent repeat assessment with a DINAMAP PRO400 monitor and BpTRU device and subsequent 24 hour ambulatory blood pressure monitoring (ABPM).
Results
The BpTRU systolic (± SD) reading (117.3 ± 14.1 mmHg) was significantly lower than the routine clinic mean systolic blood pressure (143.8 ± 15.5 mmHg; P < 0.001) and the repeat blood pressure taken with a DINAMAP PRO400 monitor in a quiet room (129.9 ± 19.9 mmHg; P < 0.001). The routine clinic mean diastolic (82.4 ± 11.2 mmHg) was significantly higher than the BpTRU reading (78.4 ± 10.0 mmHg; P < 0.001). Clinic BpTRU measurements were not significantly different to the daytime mean or overall mean of 24 hour ABPM.
Conclusions
In patients with CKD, routine clinic blood pressure measurements were significantly higher than measurements using a BpTRU machine in a quiet room, but there was no significant difference in this setting between BpTRU readings and 24 hour ABPM. Adjusting clinic protocols to utilise the most accurate blood pressure technique available is a simple manoeuvre that could deliver major improvements in clinical practice.
doi:10.1186/1471-2369-14-218
PMCID: PMC3852944  PMID: 24112304

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