A novel non-invasive blood pressure waveform measuring system compared to Millar applanation tonometry.

The accurate, non-invasive, measuring of the continuous arterial blood pressure waveform faces some difficulties and an innovative blood pressure measurement technology is urgently needed. However, the arterial blood pressure waveform plays an essential role in health care by providing diagnostic information and base for calculating several heart function parameters. The aim of this study is to introduce a novel non-invasive measuring system that can measure the arterial blood pressure waveform with high accuracy in comparison to an applanation tonometry system. The applied measuring device utilizes a new measurement strategy enabled by the OptoForce 3D force sensor, which is attached to the wrist at the radial artery. To validate the accuracy, 30 simultaneous measurements were taken with a Millar tonometer. For the simultaneously recorded non-invasive signals, the similarity was high (the average correlation was [Formula: see text]). The differences in the systolic and the diastolic blood pressure measured by the two systems are small. The average differences ([Formula: see text]) for simultaneously recorded systolic, diastolic, mean arterial and incisura pressures were: [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively. These results satisfy the AAMI criteria. Based on our results, this new system requires further development and validation against invasive arterial blood pressure monitoring in order to prove its usefulness in patient monitoring, emergency care, and pulse diagnosis.

Blood pressure measurement: clinic, home, ambulatory, and beyond.

Blood pressure traditionally has been measured in the clinic setting using the auscultatory method and a mercury sphygmomanometer. Technologic advances have led to improvements in measuring clinic blood pressure and allowed for measuring blood pressures outside the clinic. This review outlines various methods for evaluating blood pressure and the clinical utility of each type of measurement. Home blood pressures and 24-hour ambulatory blood pressures have improved our ability to evaluate the risk of target-organ damage and hypertension-related morbidity and mortality. Measuring home blood pressures may lead to more active participation in health care by patients and has the potential to improve blood pressure control. Ambulatory blood pressure monitoring enables measuring nighttime blood pressures and diurnal changes, which may be the most accurate predictors of risk associated with elevated blood pressure. Additionally, reducing nighttime blood pressure is feasible and may be an important component of effective antihypertensive therapy. Finally, estimating central aortic pressures and pulse wave velocity are 2 of the newer methods for assessing blood pressure and hypertension-related target-organ damage.

Evaluation of an oscillometric blood pressure monitor in anesthetized dogs: Agreement with direct measurements and ability to detect hypotension.

We evaluated the agreement between oscillometric and direct blood pressure monitors in anesthetized dogs and evaluated the ability of the oscillometric method to detect MAP <60 mmHg. Forty client-owned dogs, three months to 14 years old, 4.6-50.2 kg, under general anesthesia were studied. Systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were measured directly via an arterial catheter and with an oscillometric cuff (Cardell Touch monitor). Paired values were compared with mixed effect models. Bias and limits of agreement (LOA) were calculated. The sensitivity and false negative rate to detect hypotension (invasive MAP <60 mmHg) using an oscillometric MAP <60 and < 70 mmHg were calculated. A receiver operating characteristics (ROC) curve was constructed and the area under the curve calculated. SAP and DAP differed between methods (both P < 0.001), but MAP did not (P = 0.5). Bland-Altman plots showed small biases but wide LOA for all variables. The sensitivity to detect hypotension was 40% with a false negative rate of 60% when using an oscillometric MAP <60 mmHg, and 68% and 32%, respectively, with a MAP <70 mmHg. The area under the ROC curve for MAP was 0.82. While the oscillometric MAP did not differ from invasive values, the device failed to recognize hypotensive events when 60 mmHg was used as the threshold to detect hypotension. Higher MAP values increased the ability to correctly recognize hypotension, but at the expense of a higher incidence of false positives.

Accuracy of noninvasive continuous arterial pressure monitoring using ClearSight during one-lung ventilation.

ABSTRACT: Noninvasive continuous arterial pressure monitoring may be clinically useful in patients who require continuous blood pressure monitoring in situations where arterial catheter placement is limited. Many previous studies on the accuracy of the noninvasive continuous blood pressure monitoring method reported various results. However, there is no research on the effectiveness of noninvasive arterial pressure monitoring during one-lung ventilation. The purpose of this study was to compare arterial blood pressure obtained through invasive method and noninvasive method by using ClearSight during one-lung ventilation.In this retrospective observational study, a total of 26 patients undergoing one-lung ventilation for thoracic surgery at a single institution between March and July 2019 were recruited. All patients in this study were cannulated on their radial artery to measure continuously invasive blood pressures and applied ClearSight on the ipsilateral side of the cannulated arm. We compared and analyzed the agreement and trendability of blood pressure recorded with invasive and noninvasive methods during one-lung ventilation.Blood pressure and pulse rate showed a narrower limit of agreement with a percentage error value of around 30%. In addition, the tracking ability of each measurement could be determined by the concordance rate, all of which were below acceptable limits (92%).In noninvasive arterial blood pressure monitoring using ClearSight, mean blood pressure and pulse rate show acceptable agreement with the invasive method.

The mean prehospital machine; accurate prehospital non-invasive blood pressure measurement in the critically ill patient.

OBJECTIVE: Non-invasive blood pressure recordings may be inaccurate in the critically ill patient and measurement difficulties are intensified in the prehospital setting. This may adversely impact upon outcomes for many critically ill patients, particularly those with traumatic brain injury and/or lengthy prehospital times. This study aimed to validate a non-invasive, oscillometric, ambulatory blood pressure measuring device, the Oscar 2, Model 222 (SunTech Medical, Morrisville, USA) during the ambulance transport of critically ill patients. METHODS: We have previously shown that mean arterial blood pressures observed by Intensive Care Unit nurses from a patient monitor can be considered interchangeable with reference intra-arterial integrated mean pressures. In the current study, we compared non-invasive device mean pressures to intra-arterial pressures observed by retrieval nurses from the patient monitor, during the ambulance transportation of critically ill patients. Device performance was required to fulfil the Association for the Advancement of Medical Instrumentation (AAMI) protocol requirements. Additionally, linear mixed effects analyses and Bland-Altman comparisons were undertaken. RESULTS: For 157 measurements recorded from 23 patients, when the Oscar 2 did not indicate a measurement was associated with a fault, the device fulfilled the AAMI protocol requirements, with a mean error of -1.1 mmHg (standard deviation 7.8 mmHg), 95% confidence intervals (linear mixed effects analysis) -2.9, 0.8; P = 0.26. Bland-Altman plots indicated uniform agreement across a wide range of blood pressures. Sixteen percent of recordings were associated with a patient, environment, or device generated fault. CONCLUSIONS: When the Oscar 2 does not indicate a fault has occurred, clinicians may be confident the mean pressure, within acceptable limits, is accurate, even during ambulance motion, administration of high doses of vasopressors and mechanical ventilation. The Oscar 2 appears to be an accurate and rugged out-of-hospital device.

Brief online certification course for measuring blood pressure with an automated blood pressure device. A free new resource to support World Hypertension Day Oct 17, 2020.

Detection, diagnosis, and treatment of hypertension require accurate blood pressure assessment. However, in clinical practice, lack of training in or nonadherence to measurement recommendations, lack of patient preparation, unsuitable environments where blood pressure is measured, and inaccurate and inappropriate equipment are widespread and commonly lead to inaccurate blood pressure readings. This has led to calls to require regular training and certification for people assessing blood pressure. Hence, the Pan American Health Organization in collaboration with Resolve to Save Lives, the World Hypertension League, Lancet Commission on Hypertension Group, and Hypertension Canada has developed a free brief training and certification course in blood pressure measurement. The course is available at www. The release of the online certification course is timed to help support World Hypertension Day. This year World Hypertension Day has been delayed to October 17 due to the COVID-19 pandemic. For 2020, the World Hypertension League calls on all health care professionals, health care professional organizations, and indeed all of society, to assess the blood pressure of all adults, measure blood pressure accurately, and achieve blood pressure control in those with hypertension.

An Ambulatory Blood Pressure Monitor Mobile Health System for Early Warning for Stroke Risk: Longitudinal Observational Study.

BACKGROUND: Stroke, as a leading cause of death around the globe, has become a heavy burden on our society. Studies show that stroke can be predicted and prevented if a person's blood pressure (BP) status is appropriately monitored via an ambulatory blood pressure monitor (ABPM) system. However, currently there exists no efficient and user-friendly ABPM system to provide early warning for stroke risk in real-time. Moreover, most existing ABPM devices measure BP during the deflation of the cuff, which fails to reflect blood pressure accurately. OBJECTIVE: In this study, we sought to develop a new ABPM mobile health (mHealth) system that was capable of monitoring blood pressure during inflation and could detect early stroke-risk signals in real-time. METHODS: We designed an ABPM mHealth system that is based on mobile network infrastructure and mobile apps. The proposed system contains two major parts: a new ABPM device in which an inflation-type BP measurement algorithm is embedded, and an abnormal blood pressure data analysis algorithm for stroke-risk prediction services at our health data service center. For evaluation, the ABPM device was first tested using simulated signals and compared with the gold standard of a mercury sphygmomanometer. Then, the performance of our proposed mHealth system was evaluated in an observational study. RESULTS: The results are presented in two main parts: the device test and the longitudinal observational studies of the presented system. The average measurement error of the new ABPM device with the inflation-type algorithm was less than 0.55 mmHg compared to a reference device using simulated signals. Moreover, the results of correlation coefficients and agreement analyses show that there is a strong linear correlation between our device and the standard mercury sphygmomanometer. In the case of the system observational study, we collected a data set with 88 features, including real-time data, user information, and user records. Our abnormal blood pressure data analysis algorithm achieved the best performance, with an area under the curve of 0.904 for the low risk level, 0.756 for the caution risk level, and 0.912 for the high-risk level. Our system enables a patient to be aware of their risk in real-time, which improves medication adherence with risk self-management. CONCLUSIONS: To our knowledge, this device is the first ABPM device that measures blood pressure during the inflation process and has obtained a government medical license. Device tests and longitudinal observational studies were conducted in Peking University hospitals, and they showed the device's high accuracy for BP measurements, its efficiency in detecting early signs of stroke, and its efficiency at providing an early warning for stroke risk.

Validation of a wrist-type home nocturnal blood pressure monitor in the sitting and supine position according to the ANSI/AAMI/ISO81060-2:2013 guidelines: Omron HEM-9600T.

The purpose of the present study was to evaluate the performance of the Omron HEM-9600T, an automatic wrist-type device for self BP measurement, in the sitting position with the wrist at heart level and supine position according to the ANSI/AAMI/ISO81060-2:2013 guidelines. In the supine position, we evaluated the device under 3 different conditions: using the supine with sideways palm position, the supine with upwards palm position, and the supine with downwards palm position. After 106 subjects were screened and 21 subjects were excluded, the same 85 subjects (38 men [44.7%] and 47 women [55.3%]) were included in the analyses for each position. The average age of the subjects was 54.5 ± 12.2 years (mean ± SD). The mean wrist circumference was 17.0 ± 2.4 cm. The wrist size distribution fulfilled the requirements of the guidelines. The mean differences between reference BPs and HEM-9600T readings were 1.0 ± 6.7/1.4 ± 5.7 mm Hg, 6.6 ± 7.2/5.5 ± 6.0 mm Hg, 4.8 ± 7.2/4.9 ± 5.8 mm Hg, and 2.1 ± 7.2/2.8 ± 6.8 mm Hg for SBP/DBP in the sitting position, supine with sideways palm position, supine with upwards palm position, and supine with downwards palm position, respectively. In conclusion, the Omron HEM-9600T in the sitting position fulfilled the validation criteria of the ANSI/AAMI/ISO81060-2:2013 guidelines. On the other hand, the accuracies of HEM-9600T in the supine position differed depending on the positioning of the palm, with only the downwards palm-position measurement fulfilling both validation criteria of the ANSI/AAMI/ISO81060-2:2013 guidelines.

Assessment of the validation of blood pressure monitors: a statistical reappraisal.

Protocols to determine the accuracy of noninvasive blood pressure monitors have been published by the Association for the Advancement of Medical Instrumentation, the British Hypertension Society, and the European Society of Hypertension (ESH). We compared the statistical basis for each of these protocols. Although the Association for the Advancement of Medical Instrumentation and British Hypertension Society protocols require a minimum of 85 participants, the ESH protocol requires only 33 participants. The reduced sample size results in a reduction in statistical power from 98 to 70%, which brings into question the applicability of the ESH (International) protocol.

Novel methods of testing and calibration of oscillometric blood pressure monitors.

We present a robust method for testing and calibrating the performance of oscillometric non-invasive blood pressure (NIBP) monitors, using an industry standard NIBP simulator to determine the characteristic ratios used, and to explore differences between different devices. Assuming that classical auscultatory sphygmomanometry provides the best approximation to intra-arterial pressure, the results obtained from oscillometric measurements for a range of characteristic ratios are compared against a modified auscultatory method to determine an optimum characteristic ratio, Rs for systolic blood pressure (SBP), which was found to be 0.565. We demonstrate that whilst three Chinese manufactured NIBP monitors we tested used the conventional maximum amplitude algorithm (MAA) with characteristic ratios Rs = 0.4624±0.0303 (Mean±SD) and Rd = 0.6275±0.0222, another three devices manufactured in Germany and Japan either do not implement this standard protocol or used different characteristic ratios. Using a reference database of 304 records from 102 patients, containing both the Korotkoff sounds and the oscillometric waveforms, we showed that none of the devices tested used the optimal value of 0.565 for the characteristic ratio Rs, and as a result, three of the devices tested would underestimate systolic pressure by an average of 4.8mmHg, and three would overestimate the systolic pressure by an average of 6.2 mmHg.

Misleading measurements: modeling the effects of blood pressure misclassification in a United States population.

OBJECTIVE: The clinical diagnosis of hypertension is subject to misclassification, and this may be clinically important. This article calculates positive and negative predictive values for blood pressure measurement and assesses the frequency of clinically important blood pressure misclassification. DESIGN, SETTING, AND PARTICIPANTS: A modeling study was carried out on 4763 adults in the National Health and Nutrition Examination Survey (NHANES) POPULATION: True treatment eligibility was determined by applying Joint National Committee (JNC) VII criteria to individuals in the study population. Each individual was also allocated a series of blood pressures incorporating an error term reflecting day-to-day measurement variation. Test positives are persons classified as needing treatment on the basis of the mean of 2 blood pressure measurements. MEASUREMENTS AND MAIN RESULTS: Positive predictive values of a diagnosis of hypertension based on 2 measurements were calculated for each age-sex group. Low-risk false positives and highrisk false negatives were categorized as clinically important errors. Positive predictive values are high in persons older than age 65. In persons ages 16 to 34, the positive predictive value is 0.24 (95% confidence interval [CI]: 0.17-0.32) in men and 0.16 (95% CI: 0.06-0.26) in women. Persons younger than age 35 are almost always at low risk of cardiovascular disease, and therefore this misclassification is clinically important. Even with 24-hour ambulatory blood pressure measurement, positive predictive values in young adults are under 0.5. CONCLUSIONS: Blood pressure estimation is a poor diagnostic test in low-prevalence populations such as young adults. Estimation of blood pressure should be informed by prior estimation of cardiovascular risk.

National High Blood Pressure Education Program Working Group report on ambulatory blood pressure monitoring.

Blood pressure measurements obtained in a physician's office may not represent a patient's blood pressure during an entire day. Ambulatory blood pressure monitoring (ABPM) provides multiple readings over time. This review of the literature on ABPM addresses the current state of ABPM methods, normal blood pressure profiles, the clinical and research uses of ABPM, cost considerations, and recommendations for use of ABPM in selected circumstances. Current ABPM devices use either auscultatory or oscillometric methods to determine blood pressure. A rigorous comparison of these methods is needed to determine whether one method is more reliable. A nonbiased assessment of all available equipment is necessary. Normative data provided by ABPM research are needed for populations by age, race, gender, body habitus, and conditions, such as pregnancy. While ABPM is not cost-effective for all hypertensive patients, it can assist in the evaluation of such problems as target organ complications, syncopal episodes, episodic hypertension, and autonomic dysfunction.

Evaluation of an Integrated Telemonitoring Surveillance System in Patients with Coronary Heart Disease.

OBJECTIVES: Cardiovascular diseases are the most frequent cause of death in industrialized countries. Non-adherence with prescribed medication and recommended lifestyle changes significantly increases the risk of major cardiovascular events. The telemonitoring programme MyCor (Myokardinfarkt und Koronarstent Programm in Tirol) is a multi-modal intervention programme to improve lifestyle and medication management of patients with coronary heart disease (CHD). It includes patient education, self-monitoring with goal-setting and feedback, and regular clinical visits. We evaluated the MyCor telemonitoring programme regarding technical feasibility, user acceptance, patient adherence, change in health status, and change in quality of life. METHODS: A 4½-month study was conducted with two telemonitoring phases and one interim phase. The study comprised patient surveys, standardized assessment of quality of life using the MacNew questionnaire at study entry and after 4 and 18 weeks, analysis of adherence to medication and physical activity during the two telemonitoring phases, and analysis of reached goals regarding health conditions during the telemonitoring phases. RESULTS: Twenty-five patients (mean age: 63 years) participated in the study. Patients showed a high acceptance of the MyCor telemonitoring programme. Patients reported feelings of self-control, motivation for lifestyle changes, and improved quality of life. Adherence to daily measurements was high with 86% and 77% in the two telemonitoring phases. Adherence to medication was also high with up to 87% and 80%. Pre-defined goals for physical activity were reached in up to 86% and 73% of days, respectively. Quality of life improved from 5.5 at study entry to 6.3 at the end (p< 0.01; MacNew questionnaire). Reductions in blood pressure and heart rate or an improvement in reaching defined goals could not be observed. CONCLUSIONS: The MyCor telemonitoring programme Tirol for CHD patients has a high rate of acceptance among included patients. Critical evaluation revealed subjective benefits regarding quality of life and health status as well as high adherence rates to medication and lifestyle changes. Achieving long-term adherence and verifying clinical outcomes, however, remains an open issue. Our findings will promote further studies, addressing different strategies for an optimal mix of patient education, telemonitoring, feedback, and clinical follow-ups.

Accuracy and reliability of wrist-cuff devices for self-measurement of blood pressure.

OBJECT: Self-measurement of blood pressure (BP) might offer some advantages in diagnosis and therapeutic evaluation and in patient management of hypertension. Recently, wrist-cuff devices for self-measurement of BP have gained more than one-third of the world market share. In the present study, we validated wrist-cuff devices and compared the results between wrist- and arm-cuff devices. The factors affecting the accuracy of wrist-cuff devices were also studied. METHOD: The research group to assess the validity of automated blood pressure measuring device consisted of 13 institutes in Japan, which validated two wrist-cuff devices (WC-1 and WC-2) and two arm-cuff devices (AC-1 and AC-2). They used a crossover method, where the comparison was done between auscultation, by two observers by means of a double stethoscope on one arm and the device on the opposite arm or wrist. RESULTS: There was good inter-observer agreement for the auscultation method in each institute (systolic blood pressure (SBP), -0.1 +/- 2.8 mmHg; diastolic blood pressure (DBP), -0.1 +/- 2.6 mmHg, n = 498). The mean difference between auscultation and the device was minimal both in arm-cuff devices (mean difference for AC-1, 2.2/1.9 mmHg, n = 97 and for AC-2, 5.1/2.9 mmHg, n = 136, SBP/DBP) and wrist-cuff devices (mean difference for WC-1, -2.1/1.2 mmHg, n = 173 mmHg and for WC-2, -2.3/-5.6 mmHg, n = 92). The standard deviation of the difference (SDD) in wrist-cuff devices, however (SDD for WC-1, 9.7/7.3 mmHg and for WC-2, 10.2/8.6 mmHg), was larger than that of the arm-cuff devices (SDD for AC-1, 5.6/6.6 mmHg and for AC-2, 6.3/5.1 mmHg). Grading of AC-1 and AC-2 based on criteria of British Hypertension Society was A/A and B/A, respectively, while that of WC-1 and WC-2 was C/B and D/B, respectively. Using the same validation protocol, the results of validation for one device were divergent in each institute. In wrist-cuff devices, the BP value obtained in palmar flexion was significantly higher and that obtained in palmar dorsiflexion was significantly lower than that in palmar extension. In some cases, finger plethysmogram did not disappear during maximum inflation of the wrist-cuff (congruent with 250 mmHg), even in palmar extension and especially in palmar flexion, suggesting incomplete obstruction of radial and/or ulnar arteries during inflation. CONCLUSION: The results suggest that wrist-cuff devices in the present form are inadequate for self-measurement of blood pressure and, thus, are inadequate for general use or clinical and practical use. However, there is much possibility in wrist-cuff device and the accuracy and reliability of wrist-cuff device are warranted by an improvement of technology.

Ambulatory blood pressure recordings in children and adolescents.

OBJECTIVE: To provide reference data for ambulatory blood pressure monitoring (ABPM) and to determine the influence of age, sex, and race on these values. METHODS: ABPM was performed on 300 healthy, normotensive boys and girls between the ages of 10 and 18 years, including 160 boys and 140 girls, of whom 149 were white and 151 were black. Mean systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) while awake and during sleep were calculated for black and white boys and girls aged 10 to 12 years, 13 to 15 years, and 16 to 18 years. RESULTS: Boys compared with girls 10 to 12 years of age had higher mean (+/- SD) SBP (115 +/- 9 vs 112 +/- 9 mm Hg; P < .01) and DBP (67 +/- 7 vs 65 +/- 5 mm Hg; P < .01) while awake. Boys compared to girls 13 to 15 years of age had higher SBP while awake (116 +/- 11 vs 112 +/- 8 mm Hg; P < .01). Boys compared with girls 16 to 18 years of age had higher SBP while awake (125 +/- 12 vs 111 +/- 9 mm Hg); P < .01) and during sleep (116 +/- 11 vs 106 +/- 9 mm Hg). Comparisons within sex showed similar changes with age for boys and girls. Blacks compared with whites 13 to 15 years of age had higher SBP during sleep (109 +/- 11 vs 105 +/- 10 mm Hg; P < .01), and blacks compared with whites 16 to 18 years of age had higher DBP during sleep (66 +/- 7 vs 58 +/- 6 mm Hg; P < .01). Comparisons across age groups within race showed that blacks 16 to 18 years of age had higher SBP during sleep than blacks 10 to 12 years of age (109 +/- 11 vs 104 +/- 10 mm Hg), and higher DBP during sleep (66 +/- 7 mm Hg; P < .01) than blacks 10 to 12 years of age (61 +/- 7 mm Hg; P < .01) and 13 to 15 years of age (61 +/- 8; P < .01 mm Hg). The changes with age were not significant for white subjects. CONCLUSION: These results provide age-specific reference data for ABPM in youths. These values differ by sex (boys more than girls) and race (Blacks more than Whites).

The relationship between the severity of sleep apnea syndrome and 24-h blood pressure values in patients with obstructive sleep apnea.

Automated ambulatory 24-h BP monitoring was made in 38 patients with obstructive sleep apnea syndrome. Stepwise multiple regression analysis revealed that diastolic, systolic, and mean BP values during sleep as well as during wakefulness were significantly related to apnea/hypopnea index and age. Minimal arterial O2 saturation and total sleep time also significantly contributed to diastolic and mean BP values during sleep. Body mass index did not significantly contribute to any of the BP values. These results support a causal relationship between the severity of sleep apnea syndrome and systemic hypertension.

Multicenter assessment of the QuietTrak ambulatory blood pressure recorder according to the 1992 AAMI guidelines.

To clinically evaluate the QuietTrak ambulatory blood pressure (BP) recorder (Tycos-Welch-Allyn, Arden, NC), we assessed the device according to the performance criteria set out by the 1992 Association for the Advancement of Medical Instrumentation (AAMI) guidelines. The QuietTrak is a portable, noninvasive recorder that uses an auscultatory measuring system. As recommended in the 1992 AAMI guidelines, a large, heterogeneous population was recruited for the study using three clinic sites to assess accuracy and clinical performance. In addition, observer agreement and the effects of age, arm circumference, heart rate, posture, and blood pressure level on the observer-device differences were analyzed. There were 1098 simultaneous, same arm BP measurements performed in 122 subjects by the QuietTrak recorder versus two skilled clinicians per site using a teaching stethoscope and 24-h blood pressure recordings performed in 46 subjects to assess reliability of the monitor. The differences in observers for all sites were 0.7/-0.5 +/- 3.8/3.5 mm Hg with 89% of the BPs within 5 mm Hg. The mean difference between observer average and the device (all positions) was 0.3/-1.5 +/- 5.0/7.5 mm Hg. The agreement between the QuietTrak and mercury column determinations was within 10 mm Hg for 92 to 94% of systolic readings and 91 to 93% of diastolic readings, depending on the posture. The limits of agreement (2 standard deviations about the mean difference) between observers and the device for systolic BP tended to be lower for the sitting position (-11 to 10 mm Hg) compared to supine (-14 to 13 mm Hg) and standing (-14 to 14 mm Hg) positions.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of the Critikon 8100 and Spacelabs 90207 non-invasive blood pressure monitors using a test simulator.

The Critikon Dinamap 8100 and the Spacelabs 90207 ambulatory non-invasive blood pressure (NIBP) monitors were evaluated using a test simulator using an evaluation protocol which covered a wide range of simulated pressures (with five determinations at each of six steps from 60/30 to 200/150 mm Hg), pulse rates (from 40 to 200 bpm), artefact levels (simulated motion and tremor artefact) and pulse strengths (down to 10% of the nominal strength). Determinations were made at 5 min intervals. The average and standard deviation of the five measurements at each condition were calculated. The Spacelabs recorded pressures with a greater consistency than the Dinamap which showed a higher standard deviation under all the conditions. The relatively high standard deviation of the recordings made by the Dinamap could explain the non-systematic errors found in some evaluations. Both instruments recorded pressures within 5 mm Hg of the target over the range of pressures and pulse rates, and coped well under conditions of severe artefact and weak pulsations, either by signalling inability to record or by recording satisfactorily.

Measurement reliability of cardiovascular reactivity change scores: a comparison of intermittent and continuous methods of assessment.

Cardiovascular reactivity testing is a widely used measure of risk for hypertension and coronary heart disease. Evidence for the reliability of the measures, however, is weak. If the measures (usually change scores) are unreliable, the usefulness of testing is limited, since relationships with other measures, such as disease outcomes, may be obscured. This study examines the reliability of blood pressure change, using both a traditional method of assessment (Colin ABPM) which provides intermittent readings, and a non-invasive method that samples the complete distribution of pressures (Ohmeda Finapres). While the reliability for the Colin was found to be good for absolute level of individual measurements, it was extremely poor for change scores. The Finapres, however, yielded high reliabilities for change scores as well as absolute levels, due to the large number of readings taken during baseline and stressor conditions. Implications for reactivity testing methodology are discussed.

Accuracy and analysis of ambulatory blood pressure monitoring data.

Two devices used to record blood pressure, the ambulatory blood pressure monitoring recorder and standard stethoscope and mercury column, were tested for accuracy against the direct intra-arterial blood pressure of patients at rest and during exercise. Recorders were found to be as accurate as mercury column measurement in patients at rest. A number of assessment techniques of ambulatory data are reviewed, including: calculation of mean or median pressures, assessment of blood pressure load, and integration of the area under the blood pressure curve over time. These have been applied during the daytime and nighttime hours. Blood pressure load and area under the blood pressure curve, using different threshold criteria for nighttime and daytime, are recommended because of their potentially closer relation to target-organ disease of hypertension than are office blood pressure readings.