Oscillometric Blood Pressure Measurement Research Articles

Accuracy of oscillometric blood pressure measurement using a Cardell Touch multiparameter monitor in anesthetized pigs.

To assess the accuracy of an oscillometric monitor in anesthetized pigs and its ability to track changes in mean arterial pressure (MAP) and to detect arterial hypotension and hypertension in reference to direct measurements. Mean arterial pressure was measured simultaneously from a catheter in a femoral artery and with an oscillometric cuff placed over the metatarsus in 9 anesthetized pigs (∼6 months old, 35 to 55 kg). Pigs were subjected to maneuvers to alter MAP. Paired values for invasive and noninvasive MAP (iMAP and NiMAP) were recorded every 2 minutes. Bland-Altman plots with bias, limits of agreement, and percentage error were constructed using each pair and the average of 5 consecutive values. Concordance was calculated using changes in MAP at 20-minute intervals. Receiver operating characteristics (ROC) curves were constructed to test NiMAP for detection of hypotension (< 70 mm Hg) and hypertension (≥ 120 mm Hg). Bias of NiMAP was -8.59 mm Hg for consecutive pairs and -8.85 mm Hg for averaged pairs, relative to iMAP. Limits of agreement and percentage error were reduced for averages (19%) over individual pairs (26%). Concordance was 82%. The area under the ROC curve for detecting hypotension with NiMAP was 0.936, with a best cutoff value of 63 mm Hg NiMAP. The area under the ROC curve for hypertension was 0.940, with a best cutoff value of 101 mm Hg NiMAP. Averaging several consecutive values improves the accuracy of NiMAP measurements. This device correctly tracked changes in MAP approximately 80% of the time and appears reliable for diagnosing arterial hypotension.

Intraoperative hypotension in children-Measurement and treatment

Intraoperative hypotension is acommon perioperative complication in pediatric anesthesia. Oscillometric blood pressure measurement is therefore an essential part of standard perioperative monitoring in pediatric anesthesia. The optimum measurement site is the upper arm. Attention must be paid to the correct cuff size. Blood pressure should be measured before induction. In children undergoing major surgery or in critically ill children, invasive blood pressure measurement is still the gold standard. Continuous noninvasive measurement methods could be an alternative in the future.Threshold values to define hypotension remain unknown, even in awake children. There are also little data on hypotension thresholds in the perioperative setting. The most reliable measurement parameter for estimating hypotension is the mean arterial pressure. The threshold values for intraoperative hypotension are 40 mm Hg in newborns, 45 mm Hg in infants, 50 mm Hg in young children and 65 mm Hg in adolescents. Treatment should be initiated at adeviation of 10% and intensified at adeviation of 20%.Bolus administration of isotonic balanced crystalloid solutions, vasopressors and/or catecholamines are used as treatment options. Consistent and rapid intervention in the event of hypotension appears to be crucial. So far there is no evidence as to whether this leads to an improvement in outcome parameters.

P072 VALIDATION OF A NOVEL METHOD FOR NONINVASIVE ESTIMATION OF CARDIAC OUTPUT USING BRACHIAL OSCILLOMETRIC BLOOD PRESSURE MEASUREMENTS IN PATIENTS WITH VARIOUS CLINICAL CONDITIONS

Background and Objective: Estimating cardiac output (CO) and other hemodynamic parameters from blood pressure (BP) measurements could aid in selecting appropriate antihypertensive treatments in clinical settings. Our research group has developed a non-invasive method to estimate CO based on total arterial compliance (Ct). However, its validity in populations with various cardio-metabolic chronic diseases remains uncertain. The objective of this study is to assess the validity of our CO estimation method across different patient with varied clinical conditions. Methods: A cross-sectional study was conducted involving 217 adult patients who underwent ambulatory transthoracic Doppler echocardiograms, irrespective of valvular or cardiac pathology, or medication use, provided they had normal aortic valvular anatomy. Stroke volume was calculated as the product of the cross-sectional area of the aortic annulus and the average velocity of the left ventricular outflow tract. Simultaneously, oscillometric BP measurements were obtained. Subsequently, the CO values obtained via Doppler echocardiography and those estimated based on Ct were compared to determine validity. Ct was estimated as: Ct/BSA= 38/PPth + 4/5 × Td/T - 3/7, where BSA denotes body surface area, Td signifies diastolic time, T represents the cardiac period, and PPth refers to the theoretical pulse pressure. Results: Of the participants, 49.7% were men, with an average age of 54.0±14.0 years. Among them, three had a history of acute myocardial infarction, one had a pacemaker, nineteen were diabetic, and one hundred thirty-six were hypertensive. CO by echocardiography averaged 4.9±1.0 L/min, ranging from 2.0 to 8.5 L/min. The agreement of CO between the new method and Doppler echocardiography was good. Bland-Altman plots showed that the differences between the methods were randomly distributed along the mean difference line (Figure). Conclusions: The novel method for noninvasive estimation of CO based on Ct with brachial oscillometric BP measurements in patients with various clinical conditions is deemed valid. Its implementation in clinical practice has the potential to transform patient assessment.

P167 DIFFERENCES IN PULSE WAVE VELOCITY ESTIMATED USING TOTAL ARTERIAL COMPLIANCE BETWEEN SUBTYPES OF ARTERIAL HYPERTENSION

Background and Objective: Different clinical phenotypes of arterial hypertension (AH) are identified through current oscillometric blood pressure (BP) measurements. Recently, our group described hemodynamic characteristics of AH subtypes utilizing 24-hour ambulatory blood pressure monitoring (24-h ABPM). It remains unclear whether differences in PWV exist among AH subtypes, which could potentially enhance diagnostic accuracy and guide antihypertensive treatment selection. The objective was to assess the relationship between PWV, estimated using Ct, and AH subtypes. Methods: A cross-sectional study was conducted, involving 13,027 untreated patients referred for 24-h ABPM. PWV was estimated using a novel method based on Ct, derived from BP and heart rate measurements obtained during 24-h ABPM. This estimation method was developed based on the relationship between Ct and PWV as described by Vardoulis et al., utilizing the Bramwell-Hill theory and experimental research. The formula used for PWV estimation was PWV = √(36.7/(Ct/(log[age]))). Results: Among the participants, 46.5% were men, with an average age of 50.2±14.1 years and a body mass index of 27.1±4.1 kg/m2. Isolated systolic hypertension (ISH) (3.9%) exhibited the highest arterial stiffness, with the highest PWV (10.2±1.4 m/s) and pulse pressure (PP) (60.0±6.6 mmHg), and the lowest Ct (0.67±0.16 mL/mmHg). In contrast, isolated diastolic hypertension (IDH) (26.3%) showed the lowest PWV (7.9±0.8 m/s) and PP (40.6±3.6 mmHg), and the highest Ct (1.01±0.18 mL/mmHg). As Ct decreased, PWV increased. Thus, PWV based on Ct from 24-hour ABPM showed clear differences between AH subtypes (ANOVA; p value &lt; 0.001) (Figure). Conclusions: PWV is related with AH subtypes, exhibiting a progression from IDH to ISH. Patients with IDH typically have the lowest PWV, whereas those with divergent systolic-diastolic hypertension (D-SDH) and ISH have the highest PWV values. These findings underscore the significance of Ct in determining PWV values and carry diagnostic and prognostic implications concerning arterial function across various AH subtypes.

Abstract P320: Novel Pulse Waveform Index Obtained by Ambulatory Blood Pressure Monitoring is Associated with Echocardiographic Ejection Fraction in Patients with Heart Failure

Introduction: Simple, non-invasive assessment of cardiac function is useful in the management of heart failure (HF). Hypothesis: We hypothesized that pulse waveform analysis from oscillometric cuff blood pressure (BP) measurement can estimate cardiac function. The aim of this study is to investigate the association of the pulse waveform index we developed from ambulatory BP monitoring, which represents cardiac systolic function in the ambulatory setting, with echocardiographic left ventricular ejection fraction (LVEF) in patients with HF. Methods: A cuff volumetric waveform was obtained from the diastolic phase of each BP measurement with a multisensor ABPM (TM-2441, A&amp;D). The area of the ejection portion is the square forward pulse wave (Sf), which is related to the cardiac ejection. The amplitude (Am) of the waveform represents arterial and cuff compliance. Sf is divided by Am, i.e., Sf/Am, to eliminate the effect of arterial and cuff compliance, which represents left ventricular systolic function ( Figure) . Results: Patients with HF who were clinically stable in the inpatient or outpatient setting (n=195) underwent both measurements of the multisensor-ABPM and echocardiography. LVEF was determined by the modified Simpson’s method. Patient characteristics were as follows: mean age, 72.1±14.7 years; male, 57%; and atrial fibrillation (AF), 39%. Sf/Am was associated with LVEF (r=0.44, p&lt;0.001) ( Figure ). This association was also significant in the multivariable linear regression model including age, sex, body mass index, use of HF medications, coronary artery disease, and AF (β=0.43, p&lt;0.001). Conclusions: Sf/Am, which is obtained by ABPM, is associated with echocardiographic LVEF.

O87 CONCORDANCE BETWEEN NOCTURNAL CARDIAC OUTPUT ESTIMATED WITH A NOVEL NON-INVASIVE METHOD USING BRACHIAL OSCILLOMETRIC BLOOD PRESSURE MEASUREMENTS AND ECHOCARDIOGRAPHY

Background and Objective: Nocturnal hypertension, characterized by elevated blood pressure (BP) levels during sleep as measured by 24-hour ambulatory blood pressure monitoring (24-h ABPM), has garnered increasing interest. However, understanding the explanatory mechanisms and non-invasive demonstration of these alterations poses challenges. We developed a non-invasive method to estimate cardiac output (CO) using brachial oscillometric BP measurements based on total arterial compliance (Ct). Yet, the agreement between estimated nocturnal CO and echocardiography-measured CO, considered the gold standard at rest, remains uncertain. This study aims to evaluate the concordance between the two methods. Methods: A cross-sectional study was conducted involving 216 adult patients who underwent Doppler echocardiograms and 24-h ABPM, regardless of valvular or cardiac pathology, or medication use, provided they had normal aortic valvular anatomy. Stroke volume was calculated as the product of the cross-sectional area of the aortic annulus and the average velocity of the left ventricular outflow tract. Using nocturnal BP and heart rate measurements from the 24-hour ABPM, along with weight, height, age, and sex, Ct and CO were estimated. Values were compared to determine validity. Results: Of the participants, 50.0% were men, with an average age of 54.0±14.0 years. Among them, three had a history of myocardial infarction, nineteen were diabetic, and one hundred thirty-six were hypertensive. CO measured by echocardiography averaged 4.9±1.0 L/min, ranging from 2.8 to 8.1 L/min. The agreement of CO between the new method and Doppler echocardiography was good, with an intraclass correlation coefficient of 0.421 (95%CI 0.305 to 0.525). The mean difference was 0.027±0.977 L/min (95%CI -0.104 to -0.157). Bland-Altman plots demonstrated that the differences between the methods were randomly distributed along the mean difference line (Figure). Conclusions: The novel method for estimating nocturnal CO based on Ct using brachial oscillometric BP measurements demonstrate validity across various clinical conditions. Its adoption in clinical settings could simplify the assessment of nocturnal hypertension with 24-h ABPM.

Prevalence and associated factors of hypertension in adults in Lubumbashi, Democratic Republic of the Congo: A hospital cross-sectional study

Introduction: Hypertension is the leading cause of morbidity and mortality from cardiovascular disease worldwide. Knowledge of its prevalence and associated factors helps to prevent its complications. The objectives of this study were to determine the prevalence and associated factors of hypertension in hospitals in Lubumbashi, Democratic Republic of the Congo.Methods: A cross-sectional analytic study was conducted among 520 adults from February 6 to November 30, 2023 in 2 health facilities in the city of Lubumbashi (Afia Polyclinic - Don Bosco and Jason Sendwe Provincial General Reference Hospital). Participants were selected by systematic random sampling. Hypertension was defined when the subject had a blood pressure (BP) ≥ 135/85 mmHg on diurnal Ambulatory Blood Pressure Monitoring (ABPM) or ≥ 180/110 mmHg on clinic oscillometric BP measurement (OBPM), or when he/she had self-reported hypertension and/or was taking antihypertensive medication even if diurnal ABPM was normal. Factors associated with hypertension were determined using a logistic regression model at the 5% significance level.Results: The prevalence of hypertension was 32.8% (95% CI: 28.9%-37.0%). Factors significantly associated with hypertension included age ≥50 years (AOR = 4.0 [1.2-12.7]), dyslipidemia (AOR = 18.6 [3.2-107.4]), hypercalcemia (AOR = 171.6 [32.5-905.9]), hyperkalemia (AOR = 27.6 [7.1-107.8]), and hypernatremia (AOR = 948.1 [160.0-5619.3]).Conclusion: This study reveals the high hospital prevalence of hypertension and the factors associated with it, emphasizing the necessity for targeted interventions for at-risk populations, especially the elderly and those with electrolyte imbalances.

Evaluation of lingual oscillometric blood pressure measurement in anaesthetized pigs

ObjectiveTo evaluate the agreement between measurements of invasive blood pressure (IBP) and oscillometric blood pressure from the tongue (OBPton) using a multiparameter monitor. Study designUnblinded, prospective, experimental study. AnimalsA total of 12 female Large White crossbreed pigs. MethodsPigs undergoing experimental procedures that required arterial cannula placement were recruited. A blood pressure cuff with the closest width to 40% of the circumference of the tongue was placed rostral to the lingual frenulum. Systolic, mean and diastolic IBP and OBPton were measured simultaneously at 5 minute intervals. Agreement between paired measurements was examined using Bland–Altman analysis. Mean bias, precision (standard deviation of mean bias), 95% limits of agreement, correlation coefficients and percentage of measurements within 10 and 20 mmHg of IBP were calculated. ResultsThe total numbers of paired measurements recorded were 124, 126 and 124 for systolic, mean and diastolic blood pressures, respectively. The mean bias, precision and 95% limits of agreement for systolic OBPton were 11.5, 11.5 (–11.1 to 34.2), for mean OBPton 5.6, 5.7 (–5.7 to 16.8) and for diastolic OBPton 7.6, 10.1 (–12.1 to 27.4) mmHg. Correlation coefficients were greater than 0.9 for mean OBPton only. More than 50% of measurements were within 10 mmHg of IBP and 80% of measurements were within 20 mmHg of IBP for mean and diastolic OBPton only. Conclusions and clinical relevanceThe tongue as a cuff site for oscillometric blood pressure measurement is a useful site for measuring mean arterial, but not systolic or diastolic blood pressure in anaesthetized Large White crossbreed pigs. This technique fulfils the American College of Veterinary Internal Medicine criteria for measuring mean arterial pressure but not systolic or diastolic arterial pressure.

DIPPING STATUS OF BLOOD PRESSURE AND PROGNOSIS

Objective: Ambulatory blood pressure monitoring (ABPM) plays an important role in monitoring the effectiveness of antihypertensive treatment. It enables to obtain clear information about absolute values and variability of blood pressure in time-defined periods. The aim of our work was to evaluate the clinical benefit not only from the point of view of BP control, but also from the prognostic aspect by determining the diurnal index. Design and method: To control the effectiveness of antihypertensive treatment, we used ABPM - Cardiosoft-Tonoport V, General Electric (USA) with oscillometric blood pressure measurement. We analyzed 206 ABPM records in hospitalized patients. There were 93 men (45%) and 113 women (55%). The monitored group of patients was divided into 4 groups according to age. There were 31 persons in the age group of 18-44 years, 78 persons in the age group of 45-64 years, 52 persons in the age group of 65-74 years and 45 persons in the oldest age group (75 years and over). In 15 patients (7.3%), we did not determine the diurnal sign for night waking. Results: The group of dippers consisted of 79 people (38.3%), there were also 79 people (38.3%) in the group of non-dippers, there were 30 risers (14.6%) and 3 extreme dippers (1.5%). Following the further fate of the investigated persons, we found that 19 persons (9.2%) died within 2 years, of which 14 were from groups with a disturbed diurnal index (9 non-dippers and 5 risers). Conclusions: Our results point to the fact that in addition to the basic parameters of BP used as an indicator of blood pressure control, the analyses of diurnal character disturbances has a importance in prognostic aspect. Identifying these patients may therefore be helpful in the management of hypertension and comorbidities.

Comparison of routine office blood pressure measurement versus standardized attended manually activated oscillometric office blood pressure measurement in patients with chronic kidney disease.

Erroneous blood pressure measurement could lead to improper treatment and hence progression of chronic kidney disease (CKD). In routine clinical practice, there is poor adherence to the various steps to be followed during blood pressure measurement. Automated oscillometric BP measurement is difficult to perform in routine clinical practice due to several practical limitations. To evaluate the quality of blood pressure measurement and to compare routine office blood pressure measurement with standardized attended manually activated oscillometric blood pressure measurement in patients with CKD attending the nephrology outpatient department (OPD) of a tertiary care referral center. This cross-sectional study was conducted in patients aged more than 18 years with CKD stage 3-5ND, and previously diagnosed hypertension, in the nephrology OPD of a tertiary care referral center between July 2022 and September 2022. The quality of blood pressure measurement was evaluated using a questionnaire. The study participants had their blood pressure checked by both methods-routine office blood pressure and standardized attended manually activated oscillometric blood pressure. Standardized attended manually activated oscillometric blood pressure measurement yielded a significantly higher systolic blood pressure (SBP) compared to routine office blood pressure measurement (Mean SBP: 139.53 ± 29.1 vs 132.57 ± 23.59; P < 0.001). However, the diastolic blood pressure did not differ significantly between the two methods of measurement. Standardized attended manually activated oscillometric BP measurement yields a higher systolic BP compared to routine office BP measurement. Further studies are required to compare the standardized attended oscillometric BP measurement used in this study with unattended automated oscillometric BP measurement and ambulatory BP measurement.

VALIDATION OF THE SMARTPHONE BLOOD PRESSURE MEASUREMENT SOLUTION OPTIBP™ TO TRACK BLOOD PRESSURE CHANGES IN PREGNANT WOMEN

Objective: Hypertensive disorders present significant morbidity and mortality during pregnancy. While ambulatory blood pressure measurement remains the standard of care for normotensive women, self-monitoring at home is increasingly prevalent. The widespread use of smartphones worldwide has sparked interest in mobile applications that leverage the built-in hardware for blood pressure estimation, yet few trials have assessed their accuracy. Design and method: This prospective, longitudinal and monocentric study evaluated the accuracy of the OptiBP algorithm against standard oscillometric blood pressure measurements in a sample of pregnant women. Patients scheduled for elective caesarean sections were enrolled during the preoperative anesthesia consultations. Paired blood pressure measurements using OptiBP and the reference method were obtained at multiple time-points in late pregnancy and the post-partum period. Agreement between methods was assessed using the AAMI/ESH/ISO 81060-2:2018 standard thresholds of 5±8 mmHg for mean ± standard deviation of the error (criterion 1) and patient-specific standard deviation of the mean error (criterion 2) and represented graphically by Bland-Altman scatterplots. Results: Twenty-four women were enrolled of which 15 completed the protocol, yielding 166 total valid measurement pairs. Mean and standard deviation of the error were -0.74 ± 8.38 and 0.99±6.88, and the patient-specific standard deviation of the mean error was 5.84 and 3.36, for SBP and DBP respectively. Conclusions: Compared with blood pressure measure with an oscillometric device, OptiBP's blood pressure estimates meet the AAMI/ESH/ISO 81060-2:2018 criteria for DBP.

SEX DIFFERENCES IN HYPERTENSION PREVALENCE, TREATMENT AND CONTROL IN OLDER PEOPLE IN GERMANY: RESULTS OF THE NATINAL EXAMINATION SURVEY GESUNDHEIT 65+

Objective: As hypertension is closely linked to cardiovascular events, blood pressure (BP) levels and management in populations are a vital public health concern. A gender gap with higher awareness, treatment and control of hypertension in women, especially in younger women, has been repeatedly reported. We analyze recent national BP data of the Gesundheit 65+ study in older and very old men and women in Germany 2022-2023. Design and method: Nationally representative examination survey of the population aged 65 years and older residing in Germany. We analysed self-reported hypertension diagnoses, the mean of the second and third standardized oscillometric BP measurements (Mobil-O-Graph) with one of five cuffs according to upper arm circumference and Anatomical Therapeutic Chemical- (ATC) coded medication in the past 7 days. Hypertension was defined as mean systolic BP (SBP) at or above 140 mm Hg, or mean diastolic BP (DBP) at or above 90 mm Hg, or use of antihypertensives (ATC-codes C02 antihypertensives, C03 diuretics, C07 beta-blockers, C08 calcium-channel blockers or C09 ACEI and ARB) in participants with self-reported hypertension diagnosis. Awareness was defined as self-reported BP diagnosis in those with hypertension according to study definition. Provisional population weights were used. Results: BP was measured and hypertension status defined in 743 men and 686 women aged 65 to 100 years. The prevalence of hypertension according to our study definition was 58.3% [95% CI 53.2-63.3] in men and 59.5% [53.8-64.9] in women. There were no sex differences in awareness among hypertensives (men 81.7%, women 81.2%), nor in treatment among aware hypertensives (97.5% in men and women). However, control among treated hypertensives differed considerably: while 75.7% [69.2; -81.2] of men with treated hypertension had BP at or below 140/90, control among treated in women was only at 61.4% [54.2-; 68.1]. Conclusions: Our 2022-2023 national blood pressure data of people aged 65 years and older in Germany suggest a new gender gap with less hypertension control in older women compared to older men which was not yet apparent a decade ago and stands in contrast to findings in younger adults across many studies.

One size does not fit all: universal cuff overestimates oscillometric blood pressure in persons with large arm circumference

Objective Some brachial cuffs for oscillometric blood pressure (BP) measurement are claimed to cover a wide range of upper-arm circumferences; however, their validation is rarely conducted. Our aim was to compare oscillometric BP measurements obtained with a universal cuff with those obtained with an appropriately sized cuff. Methods We utilised the Microlife B6 Connect monitor, conducting oscillometric BP measurements in a random sequence with both a universal cuff (recommended for arm circumferences from 22 to 42 cm) and an appropriately sized cuff (medium for circumference 22–32 cm and large for 32–42 cm). We included 91 individuals with an arm circumference of 22–32 cm and 64 individuals with an arm circumference of 32–42 cm. Results For arm circumferences > 32 cm, systolic and diastolic BP measured with the universal cuff was higher than that measured with the large cuff (systolic 6.4 mmHg, 95% confidence interval [CI]). 3.9–8.8, diastolic 2.4 mmHg, 95%CI, 1.2–3.7, p < 0.001 for both). Overestimation of BP with the universal cuff was statistically significant after correcting for the sequence of measurements. No statistical difference was found between the universal cuff and medium cuff for circumferences in the 22–32 cm range. The bladder size in the universal cuff matched the dimensions of the medium-sized cuff; however, the cuff was larger. Conclusion Overestimation of BP measured with a universal cuff in persons with large arm circumferences is clinically important. It poses the risk of unnecessary initiation or intensification of antihypertensive medication in persons using the universal cuff.

Validation of the Mindray VS9 Vital Signs Monitor in a combined adult and pediatric population according to ISO Standard 81060-2:2018.

We aimed to validate the accuracy of the Mindray VS9 Vital Signs Monitor, which features the Mindray TrueBP inflation algorithm for oscillometric blood pressure (BP) measurement, to check if it complies with the International Organization for Standardization Standard (ISO 81060-2:2018) in a combined adult and pediatric population. A total of 86 participants, including both adult and pediatric subjects, were recruited. The distribution of their ages, gender, BPs and limb sizes all complied with the requirement of the ISO standard. The inflation and deflation algorithms were validated independently using the same-arm sequential BP measurement method. For each subject, the BP was first determined by two independent observers using a mercury sphygmomanometer (R1). The BP of the subject was then determined by the third observer using the test equipment (T1). Then, using a mercury sphygmomanometer, two independent observers were asked to determine the subject's BP (R2) again. R1-T1-R2 were considered a valid pair of data. This cycle continued until 3 pairs of valid data were achieved. We collected 258 pairs of valid BP data for the validation of the inflation and deflation algorithms respectively. For validation Criterion 1, the mean ± SD of the differences between the readings obtained from the test device and reference BP was 0.0 ± 6.6/-1.8 ± 7.1 mmHg (systolic/diastolic) when the deflation algorithm was used, and 2.4 ± 6.3/ 0.3 ± 6.9 mmHg (systolic/diastolic) when the inflation algorithm was used. For validation Criterion 2, the SD of the averaged BP differences between the test device and the reference BP per subject was 5.35/6.33 mmHg (systolic/diastolic) when the deflation algorithm was used, and 5.17/5.75 mmHg (systolic/diastolic) when the inflation algorithm was used. The VS9 Vital Signs Monitor fulfilled all the criteria in the ISO Standard. Moreover, the inflation algorithm had a shorter Measure Time (by 7-21 s) and lower maximum inflation pressure (by 9.7-22 mmHg). The VS9 Vital Signs Monitor fulfilled all the requirements of the ISO Standard (ISO 81060-2:2018) in a combined adult and pediatric population and is recommended for clinical use.

Abstract P405: Calibrating Routine Blood Pressures Among Preterm Infants: A Retrospective, Cross-Sectional Analysis

Background: Among preterm infants (&lt; 12 months postnatal age and born &lt; 37 weeks gestation), oscillometric systolic blood pressure (SBP) measurements are error-prone. However, some preterm infants have “gold standard” SBPs measured using an arterial line, in addition to the error-prone oscillometric SBPs. Objective: To compare different statistical methods to calibrate oscillometric SBPs to mimic arterial line SBPs Methods: We sampled participants from an existing pilot study of preterm infants treated with an antihypertensive therapy at the University of Alabama at Birmingham. Participants' data was obtained from the hospital's data warehouse for electronic medical records. Participants for this analysis had at least one arterial line SBP measurement, and for each of these "gold standard" measurements we identified the closest paired oscillometric SBP measurement (&lt;10 minutes apart). We also collected participant factors such as race (white vs. black/African American), gender, gestational age at birth (weeks), postnatal age at arterial line SBP measurement (weeks), and whether the participant had received an antihypertensive medication. We predicted the arterial line SBPs from oscillometric SBPs and covariates using linear regression, linear regression with restricted cubic splines, random forest, and Bayesian additive regression trees (BART). Prediction errors were calculated using 10-fold cross-validation. We used complete case analysis. Results: We identified 822 measurements among 28 participants. Ten of 28 (36%) participants were black and 13 of 28 (46%) were female. The median (Q1, Q3) gestational age at birth was 33 (29, 35) weeks. The root mean squared error for predicting arterial line SBP from oscillometric SBP by itself was 17.1 mmHg. The root mean squared error of the predicted arterial line SPBs from different statistical methods varied little from the most error (linear regression with restricted cubic splines: 13.5 mmHg) to the least error (BART: 12.6 mmHg), meaning that any calibration resulted in at least a 21% reduction in error compared to the oscillometric SBPs. BART tended to underpredict the arterial line SBPs that were above 100 mmHg. Conclusions: Among preterm infants, statistical calibration is a viable strategy for reducing the variability of error-prone oscillometric SBPs. The different statistical models performed similarly in this small pilot study, but a larger sample size using additional important variables (e.g., birth weight) is required to confirm this finding.

Comparison between invasive and oscillometric blood pressure measurements in a controlled hemorrhage model in dorsally-recumbent isoflurane-anesthetized horses

Comparison between invasive and oscillometric blood pressure measurements in a controlled hemorrhage model in dorsally-recumbent isoflurane-anesthetized horses

A comparison of invasive arterial blood pressure measurement with oscillometric non-invasive blood pressure measurement in patients with sepsis.

This study aimed to compare non-invasive oscillometric blood pressure (NIBP) measurement with invasive arterial blood pressure (IBP) measurement in patients with sepsis. We conducted a retrospective study to evaluate the agreement between IBP and NIBP using the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Paired blood pressure measurements of mean arterial pressure (MAP), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were compared using Bland-Altman analysis and paired Student's t test. We also focus on the effect of norepinephrine (NE) on the agreement between the two methods and the association between blood pressure and mortality during intensive care unit (ICU) stay. A total of 96,673 paired blood pressure measurements from 6060 unique patients were analyzed in the study. In Bland-Altman analysis, the bias (± SD, 95% limits of agreement) was 6.21mmHg (± 12.05mmHg, -17.41 to 29.83mmHg) for MAP, 0.39mmHg (± 19.25mmHg, -37.34 to 38.12mmHg) for SBP, and 0.80mmHg (± 12.92mmHg, -24.52 to 26.12mmHg) for DBP between the two techniques. Similarly, large limits of agreement were shown in different groups of NE doses. NE doses significantly affected the agreement between IBP and NIBP. SBP between the two methods gave an inconsistent assessment of patients' risk of ICU mortality. IBP and NIBP were not interchangeable in septic patients. Clinicians should be aware that non-invasive MAP was clinically and significantly underestimated invasive MAP.

Comparison of Thames Medical CAT+ Doppler and SunTech Vet 20 oscillometric devices for non-invasive blood pressure measurement in conscious cats.

A comparative assessment of systolic blood pressure (BP) measurement agreement and precision in two commonly used non-invasive BP devices was carried out in conscious cats. Systolic BP measurements were obtained from 50 conscious cats as part of their clinical investigations. All measurements were taken by the same operator and were performed according to the American College of Veterinary Internal Medicine (ACVIM) consensus guidelines. The same cuff location and cuff size were used for paired measurements. The order of device use was randomised, and an arousal score was assigned during each procedure. Precision was assessed using standard deviation and coefficient of variance comparisons. Agreement was assessed using graphical and statistical comparisons of derived 'delta mean' and 'mean of means' data. A total of 50 cats aged between 3 months and 15 years were enrolled (29 domestic shorthair, seven domestic longhair, three British Shorthair, two Ragdoll, two Sphynx, two Persian, one Siamese, one Burmese, one Russian Blue, one Maine Coon and one Oriental) with a body weight in the range of 1.2-6.2 kg. BP measurements were in the range of 95-179 mmHg. Oscillometric measurements were associated with lower arousal scores. The Doppler device demonstrated superior repeatability precision. Body weight, sex, cuff size, cuff location, arousal score and the order in which the devices were used had no significant effect on precision or agreement. Correlation between the two devices was 0.0837 and agreement was considered clinically acceptable (<10 mmHg) in 32/50 (64%) cats. Of the 18 cats with suboptimal agreement, the oscillometric mean BP was higher in 14 (78%) cats. Based on this study sample, suboptimal agreement between paired CAT+ Doppler and SunTech Vet20 oscillometric BP measurements in 36% of conscious cats suggests that these devices should not be used interchangeably. Compared with Doppler, oscillometric measurements were consistently higher, particularly at higher blood pressures. Further studies are required to assess which device has superior accuracy in conscious cats.

Smartphone-Based versus Non-Invasive Automatic Oscillometric Brachial Cuff Blood Pressure Measurements: A Prospective Method Comparison Volunteer Study.

Introduction: Mobile health diagnostics have demonstrated effectiveness in detecting and managing chronic diseases. This method comparison study aims to assess the accuracy and precision of the previously evaluated OptiBP™ technology over a four-week study period. This device uses optical signals recorded by placing a patient's fingertip on a smartphone's camera to estimate blood pressure (BP). Methods: In adult participants without cardiac arrhythmias and minimal interarm blood pressure difference (systolic arterial pressure (SAP) < 15 mmHg or diastolic arterial pressure (DAP) < 10 mmHg), three pairs of 30 s BP measurements with the OptiBP™ (test method) were simultaneously compared using three pairs of measurements with the non-invasive oscillometric brachial cuff (reference method) on the opposite arm over a period of four consecutive weeks at a rate of two measurements per week (one in the morning and one in the afternoon). The agreement of BP values between the two technologies was analyzed using Bland-Altman and error grid analyses. The performance of the smartphone application was investigated using the International Organization for Standardization (ISO) definitions, which require the bias ± standard deviation (SD) between two technologies to be lower than 5 ± 8 mmHg. Results: Among the 65 eligible volunteers, 53 participants had adequate OptiBP™ BP values. In 12 patients, no OptiBP™ BP could be measured due to inadequate signals. Only nine participants had known chronic arterial hypertension and 76% of those patients were treated. The mean bias ± SD between both technologies was -1.4 mmHg ± 10.1 mmHg for systolic arterial pressure (SAP), 0.2 mmHg ± 6.5 mmHg for diastolic arterial pressure (DAP) and -0.5 mmHg ± 6.9 mmHg for mean arterial pressure (MAP). Error grid analyses indicated that 100% of the pairs of BP measurements were located in zones A (no risk) and B (low risk). Conclusions: In a cohort of volunteers, we observed an acceptable agreement between BP values obtained with the OptiBPTM and those obtained with the reference method over a four-week period. The OptiBPTM fulfills the ISO standards for MAP and DAP (but not SAP). The error grid analyses showed that 100% measurements were located in risk zones A and B. Despite the need for some technological improvements, this application may become an important tool to measure BP in the future.

Hybrid Deep Morpho-Temporal Framework for Oscillometric Blood Pressure Measurement.

Oscillometric blood pressure (BP) measurement devices are widely utilized as the primary automated BP measurement tools in non-specialist environments. However, their accuracy and reliability vary under different settings and for different age groups and health conditions. An essential constraint of current oscillometric BP measurement devices is their analysis algorithms' incapacity to capture the BP information encoded in the pattern of recorded oscillometric pulses to its fullest extent. In this paper, we propose a new 2D oscillometric data representation that enables a full characterization of arterial system and empowers the application of deep learning to extract the most informative features correlated with BP. A hybrid convolutional-recurrent neural network was developed to capture the oscillometric pulses morphological information as well as their temporal evolution over the cuff deflation period from the 2D structure, and estimate BP. The performance of the proposed method was verified on three oscillometric databases collected from the wrist and upper arms of 245 individuals. It was found that it achieves a mean error and a standard deviation of error of as low as 0.08 mmHg and 2.4 mmHg in the estimation of systolic BP, and 0.04 mmHg and 2.2 mmHg in the estimation of diastolic BP, respectively. Our proposed method outperformed the state-of-the-art techniques and satisfied the current international standards for BP monitors by a wide margin. The proposed method shows promise toward robust and objective BP estimation in a variety of patients and monitoring situations.