Oscillometric Measurement Research Articles

Comparison of ultrasonic Doppler flow monitor, oscillometric, and direct Comparison of ultrasonic Doppler flow monitor, oscillometric, and direct arterial blood pressure measurements in anesthetized dogs

This study was performed to evaluate three different noninvasive blood pressure measurement methods (NIBP) in comparison with direct blood pressure measurements in anesthetized dogs. Ten normal healthy Beagle dogs (mean age; 3.7 ± 1.01 yrs, mean body weight 10.2 ± 1.15 kg) were enrolled in this study. The BP was measured by three different methods, i.e., Doppler (DOP), oscillometric and high density oscillometric (HDO), simultaneously for 5 times in each subject under anesthesia at three different locations (right, left front legs and tail). The blood pressure value measured by Doppler method was the most close to the value measured by the direct method. Although the accuracy and consistency of the BP measured by 3 different non-invasive methods were differed by the method, all methods except conventional oscillometric method were acceptable for monitoring systolic blood pressure in anesthetic dogs and the inter-measurement variations in DOP and HDO was minimal enough not to affect the consistency of test result.

Oscillometric Carotid to Femoral Pulse Wave Velocity Estimated With the Vicorder Device

Carotid to femoral pulse wave velocity (PWV) is associated with an increase in cardiovascular morbidity and all-cause mortality. Noninvasive approach has made this method applicable for the examination of larger populations. This study aimed to obtain reference values of PWV measured with the Vicorder device. PWV was obtained using the oscillometric Vicorder in 318 healthy, normotensive patients (165 women, 28.7±17.6 years, range 6-83 years). A plethysmographic sensor was placed over the right carotid region to pick up the carotid pulse wave and a blood pressure cuff was placed around the upper thigh to trace the femoral pulse wave. Path length was defined as the distance from the suprasternal notch to the top of the thigh cuff. Mean PWV was 6.1±1.4 m/s and significantly increased with age (r=.842; P<.0001). PWV was associated with mean arterial pressure (r=.546; P<.0001) and body mass index (r=.396; P<.0001). In a multiple linear regression model, age, mean arterial pressure, and body height emerged as independent markers for PWV. This study established reference values for carotid to femoral PWV derived by oscillometric measures that can now be used for risk stratification.

Pediatric reference values of carotid-femoral pulse wave velocity determined with an oscillometric device

A semi-automated devise for oscillometric measurement (Vicorder) of carotid-femoral pulse wave velocity (cfPWV) has been considered to be especially suited for multicenter studies in children and adolescents. Within a healthy pediatric population (156 boys/158 girls; mean age 10.8 years, range 5.0-19.6 years), the transit time of the pulse wave was measured oscillometrically (Vicorder) between a carotid and femoral cuff. For calculation of cfPWV, the traveled path length was set to 80% of the direct distance between both sites of measurement. Reference tables were generated using the maximum-likelihood curve-fitting technique and SD scores were calculated. Normalizing the same set of data with reference values specific for applanation tonometry yielded Z(at)values. Effects of sex, age, height, weight, BMI, blood pressure (BP), and heart rate on cfPWV as well as the correlation between sex-specific age-related and height-related Z(osci) and Z(at)were investigated. Sex-specific reference values and curves for cfPWV as a function of age and height are presented. cfPWV correlated positively with age, height, weight, SBP, mean arterial BP, and sex (each P < 0.005). Multiple regression analysis identified age, sex, and mean arterial pressure as significant independent predictors of cfPWV explaining 42% of the overall variability. Strong linear relationships between Z(osci) and Z(at) were noted and per sex a set of age and height-related equation for conversion was derived: Z(at),age = -0.22 + 0.68 × Z(osci),age; r = 0.98 and Z(at),height = -0.33 + 0.66 × Z(osci),height; r = 0.99 in boys and Z(at),age = -0.61 + 0.81 × Z(osci),age; r = 0.98 and Z(at),height = -0.73 + 0.72 × Z(osci),height; r = 0.97 in girls (each P < 0.001). A strong linear association between height-related oscillometric and tonometric Z-scores was observed. Age-related Z-scores are of limited value when comparing results across different populations and methods.

Accuracy of Automated Oscillometric Noninvasive Blood Pressure Measurement in the Lower Legs of Children

Accuracy of Automated Oscillometric Noninvasive Blood Pressure Measurement in the Lower Legs of Children

Detection of hypotension during Caesarean section with continuous non-invasive arterial pressure device or intermittent oscillometric arterial pressure measurement

The intensified use of spinal anaesthesia (SPA) for Caesarean section significantly contributed to a decreased maternal mortality and morbidity. Nevertheless, one of the major side-effects is hypotension after SPA with potential negative effects on the fetus. Owing to discontinuous oscillometric measurements (non-invasive arterial pressure, NIAP), hypotensive episodes may be missed. Recently, a continuous NIAP measurement device (CNAP) with acceptable agreement with the mean invasive AP was introduced. We hypothesized that CNAP detects hypotensive episodes more reliably compared with NIAP measurements. A total of 65 women undergoing Caesarean section under SPA were included in the study analysis. A total of 888 NIAP measurements obtained at 3 min cycles, starting from before SPA and continued until delivery, were analysed. When averaged over all cycles, the lowest systolic AP identified by CNAP in each cycle [105 mm Hg, (24.4)] was significantly lower (P<0.001) than the average of the individual corresponding single NIAP measurements [126 mm Hg (22.1)] and highest CNAP average [126 mm Hg (24.5)]. Hypotension (systolic AP <100 mm Hg) was detected in 39% of all cycles with CNAP and in 9% with NIAP. Hypotension was detected in 91% of the patients based on CNAP and in 55% based on NIAP. Fetal acidosis defined by an umbilical vein pH under 7.25 did not occur when the lowest systolic AP measured by CNAP was above 100 mm Hg. The CNAP device detected more hypotensive episodes after SPA and significantly lower AP compared with NIAP. AP monitoring based on CNAP may improve haemodynamic management in this patient population with potential benefit for the fetus.

Automated oscillometric measurement of the ankle–brachial index in patients with coronary artery disease

Automated oscillometric ankle-brachial index (ABI) devices were designed to measure ABI in a primary-care setting to increase the peripheral artery disease (PAD) detection rate. However, ABI measurements obtained with an automated oscillometric device may differ from those obtained using a standard ultrasound Doppler method in the general population. The purpose of this study was to compare PAD detection by the Doppler method and the automated WatchBP Office ABI system in a high-risk population with coronary artery disease (CAD). Eighty consecutive patients with confirmed CAD were included. ABI was measured by automated oscillometry followed by conventional Doppler evaluation. PAD was defined as an ABI≤0.9. Each lower extremity was analyzed separately. The Doppler method detected an ABI≤0.9 in 56 lower extremities, whereas the automated method detected an ABI≤0.9 in 28 lower extremities (P<0.0001). A Bland-Altman plot showed poor agreement between the two methods. The mean ABI values obtained by the automated and Doppler methods were significantly different (1.11±0.20 vs. 0.95±0.24; P<0.00001). The sensitivity of the automated ABI device in detecting an ABI≤0.9 was 46.3% and the specificity was 98.0%. The positive and negative predictive values for diagnosing an ABI≤0.9 using the automated oscillometric method were 92.8% and 76.9%, respectively. In conclusion, the automated WatchBP Office ABI system should be used with caution for PAD detection and screening in patients with CAD, and this system should not replace the Doppler method in populations at high risk of cardiovascular disease.

A complex pattern of agreement between oscillometric and tonometric measurement of arterial stiffness in a population-based sample

Arterial stiffness can be estimated by several noninvasive methods. In a large population-based sample we performed an agreement analysis of the set of arterial stiffness indices (ASIs) measured by tonometric (SphygmoCor) and oscillometric (Arteriograph) techniques. Central augmentation index (cAIx) and peripheral augmentation index (pAIx), as well as central SBP (cSBP) were measured in 1012 participants from a population-based study. Data were analyzed using Bland-Altman agreement analysis, multivariate adaptive regression splines and Fisher's linear discriminant analysis. In contrast to high initial correlation between two devices (r = 0.87 for pAIx, 0.88 for cAIx and 0.95 for cSBP), plotting against each other the values of measured ASIs revealed their uneven distribution and grouping into three distinctive clusters of participants. The strongest cluster discriminators were age and DBP (cluster 1: age <40, DBP 70.42 ± 7.41; cluster 2: age >40, DBP 77.36 ± 10.16; cluster 3: age >60, DBP 82.56 ± 9.48). Bland-Altman analysis of clusters showed complex differences in agreement pattern for cAIx and pAIx. For cAIx SphygmoCor gives lower readings, especially in cluster 1, whereas for pAIx Arteriograph gives lower readings in cluster 1 and higher readings in clusters 2 and 3. The agreement for pAIx was better in younger participants and the same for cAIx in older participants. ASIs obtained by SphygmoCor and Arteriograph cannot be interchangeably used as they seem to be differently influenced by predictors of arterial stiffness, predominantly by age. Different pattern of pAIx and cAIx agreement across clusters demonstrates importance of distinguishing cAIx and pAIx. Homogeneity of the study population for age should be considered when interpreting results of the studies investigating ASI.

Noncardiac Surgery

Noncardiac Surgery

Auscultatory versus oscillometric measurement of blood pressure in octogenarians

Background. Auscultatory measurement using a sphygmomanometer has been the predominant method for clinical estimation of blood pressure, but it is now rapidly being replaced by oscillometric measurement. Objective. To compare blood pressure by auscultatory and oscillometric measurements in patients ≥ 80 years. Method. 100 patients had blood pressure measured by auscultation with a sphygmomanometer and by an electronic device using the oscillometric method. For each patient the mean of two blood pressures with each method measured within 15 min were compared. Results. The mean age of participants was 85.8 years; 55.8% were women. The correlation coefficient for systolic blood pressure was 0.88 and for diastolic 0.79. Differences between auscultatory and oscillometric values were less than 10 mmHg in 70.6% of systolic blood pressures and in 83.2% for diastolic. Arrhythmia and hypertension did not influence the results, and there was no correlation between the magnitude of the differences and the level of blood pressure. Conclusion. Agreement between oscillometric and auscultatory measurements of blood pressure in octogenarians was found to be less than required by validation protocols. However, semi-automatic equipment, which is observer-independent, may be used even in the very elderly, particularly if multiple readings are performed.

New approach to beta cell function screening by nitric oxide assessment of obese individuals at the population level

BackgroundApproximately 27% of Americans today are obese, and this condition increases the prevalence of metabolic syndrome and diabetes. The UK Prospective Diabetes Study suggests that loss of beta cell function can begin at least 10 years before diagnosis, and mean beta cell function is already less than 50% at diagnosis. The aim of this research was to assess the possibility of detecting loss of beta cell function in obese patients by a novel approach involving nitric oxide assessment using a combination of technologies.Materials and methodsOne hundred and fifteen obese patients (93 women, 22 men) of mean age 39 (range 17–62) years, who were candidates for bariatric surgery were included in the study, and underwent laboratory tests, including fasting blood glucose, fasting insulin plasma, and examination with the Electro Sensor complex. The Electro Sensor complex offers a new way to assess nitric oxide production using five technologies managed by software, ie, the galvanic skin response, photoelectrical plethysmography, heart rate variability analysis, bioimpedance analysis, and blood pressure oscillometric measurements. The homeostasis model assessment 2% beta cell function (HOMA2% β) algorithm was calculated from fasting blood glucose and fasting insulin plasma using free software provided by The University of Oxford Diabetes Trial Unit. The Electro Sensor complex percent beta (ESC% β) algorithm was calculated from the Electro Sensor complex data and statistical neural network. Statistical analysis was performed to correlate ESC% β and HOMA2% β using the coefficient of correlation and Spearman’s coefficient of rank correlation. Receiver-operating characteristic curves were also constructed to determine the specificity and sensitivity of ESC% β in detecting a HOMA2% β value < 100.ResultsThe coefficient of correlation between ESC% β and HOMA2% β was 0.72 (using log values) and the Spearman’s coefficient of rank correlation (rho) was 0.799 (P < 0.0001). ESC% β had a sensitivity of 77.14% and specificity of 78.21% (cutoff ≤ 157, corresponding to 40% after conversion into a 0%–100% scale) to detect a HOMA2% β value < 100 (P < 0.0001).ConclusionThe ESC% β algorithm has a high predictive correlation with HOMA2% β, and good specificity and sensitivity to detect a HOMA2% β value < 100. Therefore, the Electro Sensor complex enabling nitric oxide assessment represents a novel method of screening for beta cell function in the obese population on a large scale. Such a tool, which is easy to administer, noninvasive, and cost-effective, would be of great benefit for widespread screening of beta cell function in obese patients.

A rare cause of hypertension in a healthy 2-year-old female: Questions

A previously healthy 2-year-old Caucasian female was admitted to the hospital for dehydration secondary to a diarrheal illness. In the emergency department, she was noted to be hypertensive, and this persisted throughout her admission, including during sleep. Her average blood pressure was elevated at 140/90 mmHg by Dinamap oscillometric measurements. High blood pressure readings were confirmed by sphygmomanometry. She received intravenous fluids and was discharged home two and a half days later. The elevated blood pressure was not investigated during the admission, but follow-up was arranged with a community pediatrician to reassess her blood pressure in an outpatient setting. Her hypertension persisted at that appointment, prompting a workup for potential causes. This young girl was otherwise healthy with no significant prenatal, perinatal, or past medical history. A review of systems was unremarkable. She was growing and developing appropriately. Her parents did not recall her blood pressure being measured in the past. She was on no medications. There was a family history of hypertension in the maternal grandmother and paternal great-grandmother, both of which were diagnosed in adulthood. She had a healthy, normotensive 4-year-old brother. Parents were also normotensive. Physical examination was unremarkable aside from the elevated blood pressure of 145/90 mmHg by auscultation (>99th percentile for age and height). Measurements were similar in all four extremities. Heart rate was normal at 110 bpm. Weight was 16.1 kg (>95th percentile) and height was 94.5 cm (>95th percentile). BMI was 18 kg/m (85th percentile). She was not dysmorphic. Cardiac examination was normal. There was no abdominal mass or bruit. She had no edema. She had normal female external genitalia. The exam was otherwise normal. The pediatrician’s workup included the following: sodium 140 mmol/l, potassium 3.8mmol/l, total calcium 10mg/dl, bicarbonate 24 mmol/l, creatinine 0.37 mg/dl, and BUN 5.6 mg/dl (all within normal limits). Urinalysis was negative The answers to these questions can be found at doi:10.1007/s00467012-2164-2.

Electrocardiogram-Assisted Blood Pressure Estimation

Accurate automatic noninvasive assessment of blood pressure (BP) presents a challenge due to conditions like arrhythmias, obesity, and postural changes that tend to obfuscate arterial amplitude pulsations sensed by the cuff. Researchers tried to overcome this challenge by analyzing oscillometric pulses with the aid of a higher fidelity signal-the electrocardiogram (ECG). Moreover, pulse transit time (PTT) was employed to provide an additional method for BP estimation. However, these methods were not fully developed, suitably integrated, or tested. To address these issues, we present a novel method whereby ECG-assisted oscillometric and PTT (measured between ECG R-peaks and maximum slope of arterial pulse peaks) analyses are seamlessly integrated into the oscillometric BP measurement paradigm. The method bolsters oscillometric analysis (amplitude modulation) with more reliable ECG R-peaks provides a complementary measure with PTT analysis (temporal modulation) and fuses this information for robust BP estimation. We have integrated this technology into a prototype that comprises a BP cuff with an embedded conductive fabric ECG electrode, associated hardware, and algorithms. A pilot study has been undertaken on ten healthy subjects (150 recordings) to validate the performance of our prototype against United States Food and Drug Administration approved Omron oscillometric monitor (HEM-790IT). Our prototype achieves mean absolute difference of less than 5 mmHg and grade A as per the British Hypertension Society protocol for estimating BP, with the reference Omron monitor.

Analyzing the Windkessel Model as a Potential Candidate for Correcting Oscillometric Blood-Pressure Measurements

Developing a good model for oscillometric blood-pressure measurements is a hard task. This is mainly due to the fact that the systolic and diastolic pressures cannot be directly measured by noninvasive automatic oscillometric blood-pressure meters (NIBP) but need to be computed based on some kind of algorithm. This is in strong contrast with the classical Korotkoff method, where the diastolic and systolic blood pressures can be directly measured by a sphygmomanometer. Although an NIBP returns results similar to the Korotkoff method for patients with normal blood pressures, a big discrepancy exist between both methods for severe hyper- and hypotension. For these severe cases, a statistical model is needed to compensate or calibrate the oscillometric blood-pressure meters. Although different statistical models have been already studied, no immediate calibration method has been proposed. The reason is that the step from a model, describing the measurements, to a calibration, correcting the blood-pressure meters, is a rather large leap. In this paper, we study a “databased” Fourier series approach to model the oscillometric waveform and use the Windkessel model for the blood flow to correct the oscillometric blood-pressure meters. The method is validated on a measurement campaign consisting of healthy patients and patients suffering from either hyper- or hypotension.

Changes in blood pressure during healthy pregnancy

To study longitudinally changes in blood pressure (BP) and heart rate (HR) during healthy pregnancies and to evaluate the influence of parity, pregestational overweight, and excessive weight gain. A prospective longitudinal cohort study of 57 healthy white women with singleton pregnancies. BP and HR were measured repeatedly at gestational age 14-16 weeks, 22-24 weeks, 30-32 weeks, 36 weeks, and 6 months postpartum using both an oscillometric measurement device (Dinamap) and finger arterial pressure (Finometer PRO). SBP, DBP, and mean arterial pressure (MAP) reached a statistically significant trough at gestational age 22-24 weeks using both measurement devices. When compared with the nonpregnant measurement, SBP at gestational age 22-24 weeks was 6.2 mmHg [95% confidence interval (95% CI) 1.3-11.2] lower measured by Finometer and 7.2 mmHg (95% CI 4.2-10.1) lower measured by Dinamap. DBP and MAP were 8.9 mmHg (95% CI 4.6-13.2) and 9.8 mmHg (95% CI 5.3-14.2) lower measured by Finometer. Measured by Dinamap, DBP and MAP were 4.5 mmHg (95% CI 1.7-7.3) and 5.4 mmHg (95% CI 2.8-7.9) lower at gestational age 22-24 weeks when compared with the nonpregnant state. SBP was significantly higher in women with pregestational BMI at least 25 kg/m with both measurement devices (both P < 0.05). There were no differences in SBP, DBP, or MAP depending on parity or excessive weight gain. BP measured repeatedly by two different noninvasive devices during pregnancy and postpartum showed a statistically significant drop in mid-pregnancy, followed by a progressive increase until term.

Comparison of blood pressure measurements between an automated oscillometric device and a Hawksley random-zero sphygmomanometer in the northern Sweden MONICA study

The Hawksley random-zero sphygmomanometer (random-zero) has been used widely in epidemiological observation studies. This study compares blood pressure measurements using the random-zero with measurements using an automated oscillometric device and suggests a correction of the automated oscillometric measurements to enable comparisons of blood pressure levels over time. The northern Sweden MONICA population survey 2009 included 1729 participants, 853 men and 876 women, 25-74 years old. Blood pressure was measured using both random-zero and an automated oscillometric device in all participants. The Omron M7 digital blood pressure monitor was used for automated oscillometric measurements. A linear mixed model was used to derive a formula to adjust the automated oscillometric readings. Automated oscillometric measurements of systolic blood pressure were generally lower than random-zero measurements in women [oscillometric mean 122.1 mmHg (95% confidence interval: 121.0-123.2) versus random-zero mean 124.4 mmHg (123.5-125.5)], whereas automated oscillometric measurements of systolic blood pressure were generally higher than random-zero measurements in men [oscillometric 131.1 mmHg (130.0-132.2) versus random-zero 129.0 mmHg (127.9-130.1)]. For diastolic blood pressure, automated oscillometric measurements were higher in both women [oscillometric 79.9 mmHg (79.2-80.5) versus random-zero 76.7 mmHg (76.0-77.4)] and men [oscillometric 83.1 mmHg (82.4-83.8) vs. random-zero 81.2 mmHg (80.6-81.9)]. The difference also varied with age and order of measurement. Adjustment of the automated oscillometric measurements using mixed model regression coefficients produced estimates of blood pressure that were close to the random-zero measurements. Blood pressure measurements using an automated oscillometric device differ from those with random-zero, but the oscillometric measurements can be adjusted, on the basis of sex, age and measurement order, to be similar to the random-zero measurements.

The Effects of Brachial Arterial Stiffening on The Accuracy of Oscillometric Blood Pressure Measurement: A Computational Model Study

Oscillometric noninvasive blood pressure measurement (ONBPM) is nowadays widely applied in health care. However, ONBPM has been found to exhibit large interindividual variability in accuracy. In the present study, we developed a theoretical model to describe the mechanics of the brachial arterial wall and particularly arterial stiffening dominated respectively by wall thickening and elastin degeneration. The model was incorporated into a cardiovascular-cuff model to investigate the effects of brachial arterial stiffening on the accuracy of ONBPM. It was found that wall-thickening-dominated arterial stiffening induced overestimate of the systolic pressure, whereas the elastin-degeneration-dominated arterial stiffening induced overestimate of both the systolic pressure and the diastolic pressure. The findings support the clinical observation that pseudo-hypertension is more prevalent in the elderly, and at the same time imply that arterial stiffness indices (e.g., compliance of artery, pulse wave velocity) assessed under the physiological pressure (generally between 70 and 150mmHg) conditions may be insufficient for assessing the accuracy of ONBPM.

Non-invasive assessment of arterial stiffness using oscillometric blood pressure measurement

BackgroundArterial stiffness is a major contributor to cardiovascular diseases. Because current methods of measuring arterial stiffness are technically demanding, the purpose of this study was to develop a simple method of evaluating arterial stiffness using oscillometric blood pressure measurement.MethodsBlood pressure was conventionally measured in the left upper arm of 173 individuals using an inflatable cuff. Using the time series of occlusive cuff pressure and the amplitudes of pulse oscillations, we calculated local slopes of the curve between the decreasing cuff pressure and corresponding arterial volume. Whole pressure-volume curve was derived from numerical integration of the local slopes. The curve was fitted using an equation and we identified a numerical coefficient of the equation as an index of arterial stiffness (Arterial Pressure-volume Index, API). We also measured brachial-ankle (baPWV) PWV and carotid-femoral (cfPWV) PWV using a vascular testing device and compared the values with API. Furthermore, we assessed carotid arterial compliance using ultrasound images to compare with API.ResultsThe slope of the calculated pressure-volume curve was steeper for compliant (low baPWV or cfPWV) than stiff (high baPWV or cfPWV) arteries. API was related to baPWV (r = -0.53, P < 0.05), cfPWV (r = -0.49, P < 0.05), and carotid arterial compliance (r = 0.32, P < 0.05). A stepwise multiple regression analysis demonstrated that baPWV and carotid arterial compliance were the independent determinants of API, and that API was the independent determinant of baPWV and carotid arterial compliance.ConclusionsThese results suggest that our method can simply and simultaneously evaluate arterial stiffness and blood pressure based on oscillometric measurements of blood pressure.

Monitoring Personalized Trait Using Oscillometric Arterial Blood Pressure Measurements

The blood pressure patterns obtained from a linearly or stepwise deflating cuff exhibit personalized traits, such as fairly uniform peak patterns and regular beat geometry; it can support the diagnosis and monitoring of hypertensive patients with reduced sensitivity to fluctuations in Blood Pressure (BP) over time. Monitoring of personalized trait in Oscillometric Arterial Blood Pressure Measurements (OABPM) uses the Linear Discriminant Analysis (LDA) algorithm. The representation of personalized traits with features from the oscillometric waveforms using LDA algorithm includes four phases. Data collection consists of blood pressure data using auscultatory measurements and pressure oscillations data obtained from the oscillometric method. Preprocessing involves the normalization of various sized oscillometric waveforms to a uniform size. Feature extraction involves the use of features from oscillometric amplitudes, and trait identification involves the use of the LDA algorithm. In this paper, it presents a novel OABPM‐based blood pressure monitoring system that can monitor personalized blood pressure pattern. Our approach can reduce sensitivity to fluctuations in blood pressure with the features extracted from the whole area in oscillometric arterial blood pressure measurement. Therefore this technique offers reliable blood pressure patterns. This study provides a cornerstone for the diagnosis and management of hypertension in the foreseeable future.

Oscillometric measurement of systolic and diastolic blood pressures validated in a physiologic mathematical model

BackgroundThe 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.MethodsA 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.ResultsThe 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.ConclusionsA 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.

Reliability of Resting Blood Pressure Measurement and Classification Using an Oscillometric Device in Children with Chronic Kidney Disease

To compare the reliability of blood pressure (BP) readings obtained with an oscillometric device with those obtained by auscultation and assess for differences in BP status classification based on the 2 techniques. Resting BP was measured by auscultation and with an oscillometric device at the same encounter in 235 subjects enrolled in the Chronic Kidney Disease in Children study. Resting auscultatory BP values were averaged and compared with averaged oscillometric readings. BP agreement by the 2 methods was assessed using Bland-Altman plots, and BP status classification agreement was assessed by calculation of kappa statistics. Oscillometric BP readings were higher than auscultatory readings, with a median paired difference of 9 mm Hg for systolic BP (SBP) and 6 mm Hg for diastolic BP (DBP). Correlation for mean SBP was 0.624 and for mean DBP was 0.491. The bias for oscillometric BP measurement was 8.7 mm Hg for SBP (P < .01) and 5.7 mm Hg for DBP (P < .01). BP status classification agreement was 61% for SBP and 63% for DBP, with Kappa values of .31 for SBP and .20 for DBP. Compared with auscultation, the oscillometric device significantly overestimated both SBP and DBP, leading to frequent misclassification of BP status.