Forced oscillatory parameters as predictors of COPD assessment test improvement in untreated COPD patients.

BACKGROUND: Few studies have examined whether baseline spirometry and the forced oscillation technique (FOT) would predict The COPD Assessment Test (CAT) score improvement after treatment of untreated COPD patients. METHODS: The study subjects included 65 untreated COPD patients. They underwent the CAT, spirometry, and FOT (MostGraph) before and after treatment for more than 2 months. In addition, recursive partitioning analysis was performed using spirometry and the FOT parameters to identify the predictors of CAT improvement (CAT score ≥2). RESULTS: CAT scores and lung function significantly improved after treatment. Recursive partitioning analysis identified 3 improved classes, defined by Rrs at 20 Hz (R20), Xrs at 5 Hz (X5), and ΔX5, but not by spirometry. The accuracy of predicting CAT improvement was as follows: odds ratio, 25.3; 95 % confidence interval, 6.1 to 104.1; sensitivity, 91.2 %; specificity, 71.0 %; positive likelihood ratio, 3.14; and negative likelihood ratio, 0.12. CONCLUSIONS: FOT helps predict improved health status in untreated COPD patients.

The sensitivity and specificity of the forced oscillation technique in the diagnosis of bronchoconstriction in children.

OBJECTIVE: The forced oscillation technique (FOT) is a useful diagnostic respiratory system for children. However, the final value of the FOT in the diagnosis of bronchoconstriction is still open. The aim of the study was to evaluate the sensitivity and specificity of the FOT vs. body plethysmography tests in the measure of bronchoconstriction in asthmatic children. MATERIALS AND METHODS: A total of 102 children aged 2 to 6 years diagnosed with early-onset asthma and 52 healthy controls were included in this prospective, randomized study. All asthmatic patients and healthy controls underwent a basic FOT as one measurement, according to the recommendation of the Resmon Pro FOT. Then, the reversibility test was performed 20 min after the administration of 200 mg salbutamol using the FOT and body plethysmography in all patients. RESULTS: The mean basic Rrs, Xrs and sRaw in asthmatic patients were, respectively, 11.13 ± 1.28 kPa sL-1, -4.6 ± 1.18 kPa sL-1 and 1.72 ± 0.58 kPa s. Similar parameters were significantly better in the control group (p < 0.05). A total of 73 (71.6%) asthmatic patients had a positive test using the FOT according to Calogero. In 4 (7.7%) patients in the control group, a positive test was obtained. In body plethysmography, similar results were reached, with a positive test in 76 (74.5%) study patients and 5 (9.6%) control patients. CONCLUSIONS: A bronchial reversibility test with the use of the FOT is useful for the diagnosis of bronchial asthma, especially with the use of an Rrs parameter, such as the body plethysmography test.

Clinical Evaluation of a High-fidelity Upper Arm Cuff to Measure Arterial Blood Pressure during Noncardiac Surgery.

BACKGROUND: In most patients having noncardiac surgery, blood pressure is measured with the oscillometric upper arm cuff method. Although the method is noninvasive and practical, it is known to overestimate intraarterial pressure in hypotension and to underestimate it in hypertension. A high-fidelity upper arm cuff incorporating a hydraulic sensor pad was recently developed. The aim of the present study was to investigate whether noninvasive blood pressure measurements with the new high-fidelity cuff correspond to invasive measurements with a femoral artery catheter, especially at low blood pressure. METHODS: Simultaneous measurements of blood pressure recorded from a femoral arterial catheter and from the high-fidelity upper arm cuff were compared in 110 patients having major abdominal surgery or neurosurgery. RESULTS: 550 pairs of blood pressure measurements (5 pairs per patient) were considered for analysis. For mean arterial pressure measurements, the average bias was 0 mmHg, and the precision was 3 mmHg. The Pearson correlation coefficient was 0.96 (P < 0.0001; 95% CI, 0.96 to 0.97), and the percentage error was 9%. Error grid analysis showed that the proportions of mean arterial pressure measurements done with the high-fidelity cuff method were 98.4% in zone A (no risk), 1.6% in zone B (low risk) and 0% in zones C, D, and E (moderate, significant, and dangerous risk, respectively). The high-fidelity cuff method detected mean arterial pressure values less than 65 mmHg with a sensitivity of 84% (95% CI, 74 to 92%) and a specificity of 97% (95% CI, 95% to 98%). To detect changes in mean arterial pressure of more than 5 mmHg, the concordance rate between the two methods was 99.7%. Comparable accuracy and precision were observed for systolic and diastolic blood pressure measurements. CONCLUSIONS: The new high-fidelity upper arm cuff method met the current international standards in terms of accuracy and precision. It was also very accurate to track changes in blood pressure and reliably detect severe hypotension during noncardiac surgery.

Response to exercise-induced blood pressure elevation is blunted in wrist-cuff automated oscillometric measurement in healthy young college students.

BACKGROUND: A wrist-cuff automated oscillometric device is portable and useful for self-monitoring of blood pressure (BP) at home and outdoors when an upper arm device is not available. Although the height of the forearm in wrist BP measurement is acknowledged to be the major cause of measurement error, it remains unclear whether exercise affects subsequent wrist BP measurement. METHODS AND RESULTS: Ninety-seven healthy college students (median age of 20 years with an age range of 19 to 36 years, 70.1% males) participated in this study. Care was taken to keep the position of the wrist at a level near the upper arm level in BP measurement. At rest, BP measured by a wrist-cuff oscillometric device (Omron HEM-6183) was generally acceptable when it was compared with BP measured by an upper arm oscillometric device (Omron HEM-7130-HP) and with BP measured by the auscultatory method using a mercury sphygmomanometer. However, the ratio of systolic BP measured by oscillometric devices just after a two-step exercise test to that before exercise on the wrist (1.22 ± 0.14) was significantly lower than the ratio on the upper arm (1.27 ± 0.14), and the difference was significantly correlated with exercise-induced increase in pulse rate (Spearman's ρ = 0.23), suggesting a possible role of autonomic nerve activity in the blunted response to exercise-induced BP elevation in wrist BP measurement. CONCLUSIONS: The results indicate that the blunted response to exercise-induced BP elevation should be considered in wrist BP measurement when using a wrist-cuff oscillometric device.

The impact of calibration approaches on the accuracy of oscillometric central aortic blood pressure measurement.

BACKGROUND: Two fully automated oscillometric devices have become available for the noninvasive assessment of central aortic blood pressure (BP). They tend, however, to underestimate SBP. It has been proposed that calibration by mean/diastolic instead of systolic/diastolic brachial BP may reduce this bias. The present work compares the accuracy of these two calibrations in the Mobil-O-Graph. METHODS: Post-hoc analysis of the largest validation study on noninvasive assessment of central BP so far. Data on both calibration approaches were available in 159 patients without atrial fibrillation, who underwent simultaneous invasive and noninvasive assessment of central BP. Noninvasive BP measurements were conducted using the SphygmoCor XCEL (calibration by systolic/diastolic brachial BP only) and the Mobil-O-Graph (calibration by both systolic/diastolic and mean/diastolic brachial BP). RESULTS: Measurements of both devices and both calibration methods revealed highly significant correlations for systolic and diastolic central BP with invasively assessed BP (P < 0.001 each). Calibration by mean/diastolic and systolic/diastolic BP yielded similar correlations for central DBP (R 0.56 vs. R 0.55, P = 0.919). Correlation of central SBP, however, was significantly lower using calibration by mean/diastolic brachial BP (R 0.86 vs. R 0.74, P = 0.002). Numerically, the SphygmoCor device revealed the highest correlation (R 0.92 for central SBP and 0.72 for central DBP; P < 0.001 each). Calibration by systolic/diastolic brachial BP was associated with an underestimation of central SBP using both the SphygmoCor and the Mobil-O-Graph. Calibration by mean/diastolic brachial BP, instead, was associated with an overestimation, which was numerically comparable (4.8 ±â€Š11.3 vs. -4.2 ±â€Š8.0). The calibration method had little effects on the biases of diastolic measurements. CONCLUSION: Calibration by mean/diastolic instead of systolic/diastolic brachial BP led to an overestimation instead of underestimation of central SBP without improving accuracy. Hence, mean/diastolic calibration is not necessarily superior to systolic/diastolic calibration and the optimal approach has to be determined in a device-specific manner.

Validation of the InBody BP170 oscillometric home blood pressure monitor in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization Universal Standard.

OBJECTIVE: To evaluate the accuracy of the InBody BP170 oscillometric upper-arm home blood pressure (BP) monitor in general population according to the Association for the Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) Universal Standard (ISO 81060-2:2018). METHODS: Subjects were recruited to fulfill the age, gender, BP and cuff distribution criteria of the AAMI/ESH/ISO Universal Standard in general population using the same arm sequential BP measurement method. Two cuffs of the test device were used for arm circumference 22-32 (medium) and 32-42 cm (large). RESULTS: One-hundred five subjects were recruited and 88 were analyzed. For validation Criterion 1, the mean ± SD of the differences between the test device and reference BP readings was 0.9 ± 6.9/0.5 ± 5.5 mmHg (systolic/diastolic). For Criterion 2, the SD of the averaged BP differences between the test device and reference BP per subject was 5.77/4.80 mmHg (systolic/diastolic). CONCLUSION: The InBody BP170 oscillometric home BP monitor fulfilled all the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2:2018) in general population and can be recommended for clinical use.

Blood pressure measurement by oscillometric and auscultatory methods in normotensive pregnant women.

OBJECTIVE: to compare blood pressure values obtained by auscultatory and oscillometric methods in different gestational periods, considering cuff width. METHOD: it is a cross-sectional and quasi-experimental study approved by the Research Ethics Committee. The sample consisted of 108 low-risk pregnant women. Blood pressure measurements were performed in gestational periods of 10-14, 19-22 and 27-30 weeks. RESULTS: The oscillometric device presented values similar to the auscultatory method in systolic blood pressure, but overestimated diastolic blood pressure. Underestimation of blood pressure occurred when using the standard width cuff rather than the correct width cuff in both measuring methods. CONCLUSION: Verification of brachial circumference and use of adequate cuffs in both methods are indispensable to obtain reliable blood pressure values in pregnant women. We recommend performance of additional studies to evaluate diastolic blood pressure overestimation by the Microlife 3BTO-A.

Assessment of a commercially available veterinary blood pressure device used on awake and anesthetized dogs.

OBJECTIVE: To compare results of a commercially available device for oscillometrically measured blood pressure (OBP) with invasively measured blood pressure (IBP) in awake and anesthetized dogs. ANIMALS: 19 adult dogs (mean ± SD body weight, 17.8 ± 7.5 kg). PROCEDURES: Blood pressures were measured in dogs while they were awake and anesthetized with isoflurane. The OBP was recorded on a thoracic limb, and IBP was simultaneously recorded from the median caudal artery. Agreement between OBP and IBP was evaluated with the Bland-Altman method. Guidelines of the American College of Veterinary Internal Medicine (ACVIM) were used for validation of the oscillometric device. RESULTS: In awake dogs, mean bias of the oscillometric device was -11.12 mm Hg (95% limits of agreement [LOA], -61.14 to 38.90 mm Hg) for systolic arterial blood pressure (SAP), 9.39 mm Hg (LOA, -28.26 to 47.04 mm Hg) for diastolic arterial blood pressure (DAP), and -0.85 mm Hg (LOA, -40.54 to 38.84 mm Hg) for mean arterial blood pressure (MAP). In anesthetized dogs, mean bias was -12.27 mm Hg (LOA, -47.36 to 22.82 mm Hg) for SAP, -3.92 mm Hg (LOA, -25.28 to 17.44 mm Hg) for DAP, and -7.89 mm Hg (LOA, -32.31 to 16.53 mm Hg) for MAP. The oscillometric device did not fulfill ACVIM guidelines for the validation of such devices. CONCLUSIONS AND CLINICAL RELEVANCE: Agreement between OBP and IBP results for awake and anesthetized dogs was poor. The oscillometric blood pressure device did not fulfill ACVIM guidelines for validation. Therefore, clinical use of this device cannot be recommended.

Calibrating Local Population-Based Blood Pressure Data from NYC HANES 2013-2014.

New York City Health and Nutrition Examination Survey (NYC HANES) was a population-based cross-sectional survey of NYC adults conducted twice, in 2004 and again in 2013-2014, to monitor the health of NYC adults 20 years or older. While blood pressure was measured in both surveys, an auscultatory mercury sphygmomanometer was used to measure blood pressure in clinics in 2004, and an oscillometric LifeSource UA-789AC monitor was used in homes in 2013-2014. To assess comparability of blood pressure results across both surveys, we undertook a randomized study comparing blood pressure (BP) readings by the two devices. Blood pressure measuring protocols followed the 2013 Association for the Advancement in Medical instrumentation guidelines for non-invasive blood pressure device. Data from 167 volunteers were analyzed for this purpose.Paired t tests were used to test for significant difference in mean systolic and diastolic blood pressure between devices for overall and by mid-arm circumference categories. To test for systematic differences between the two devices, we generated Bland-Altman graphs. Sensitivity, specificity, and Kappa statistics were calculated to assess between-device agreement for high (≥ 130/80 mmHg) and not high (< 130/80 mmHg) blood pressure, with mercury set as the reference.Systolic and diastolic blood pressure measured by LifeSource UA-789AC were on average 2.0 and 1.1 mmHg higher, respectively, than those of the mercury sphygmomanometer systolic and diastolic blood pressure readings (P < 0.05). Sensitivity was 81%, specificity was 96%, and the Kappa coefficient was 75%. The Bland-Altman graphs showed that the between-device difference did not vary as a function of the average of the two devices for systolic blood pressure and was larger in the lower and upper ends for diastolic blood pressure. Given the observed differences in systolic and diastolic blood pressure readings between the two blood pressure measurement approaches, we calibrated NYC HANES 2013-2014 blood pressure data by predicting mercury blood pressure values from LifeSource blood pressure values. The mean systolic and diastolic blood pressure in NYC HANES 2013-2014 were lower when data were calibrated.

Impulse oscillometry.

Pulmonary function testing involves a battery of tests from the simple pulse oximetry to the cardiopulmonary exercise testing. Impulse oscillometry (IOS) is one of the newly described pulmonary function tests. It is based on the old principle of forced oscillatory technique modified and refined as per research and advances. It involves the use of sound waves during normal tidal breathing, which gives information on oscillatory pressure-flow relationships and eventually resistance and reactance. The resistance at 20 Hz (R20) represents the resistance of the large airways. The resistance at 5 Hz (R5) means the total airway resistance. (R5-R20) reflects resistance in the small airways. The reactance at 5 Hz (X5) indicates the elastic recoil of the peripheral airways. Resonant frequency and area of reactance are also measured. IOS has major uses in diagnosis and control of asthma in children and the elderly, where spirometry is otherwise normal. IOS has been studied in other respiratory diseases like COPD, ILD and supraglottic stenosis.

Calibration of blood pressure measurements in the Jackson Heart Study.

BACKGROUND: In longitudinal research studies with follow-up examinations, the devices used to measure phenotypes may change over time. When a device change occurs, the two devices should be calibrated to each other to ensure that measurements are comparable. This paper details the Jackson Heart Study (JHS) blood pressure (BP) comparability study. PARTICIPANTS AND METHODS: During its second clinic exam (2005-2008), the JHS switched from a random-zero sphygmomanometer (RZS) BP measurement device to an oscillometric device (OD). During this exam, BP measurements from both an RZS and an OD were taken simultaneously in 2117 participants for the purpose of calibration. Five methods for calibrating systolic BP (SBP) and diastolic BP (DBP) were considered: ignoring the change, ordinary least squares regression, adding the average difference, Deming regression, and robust regression. RESULTS: Using the RZS and OD, the mean (SD) SBP was 125.5 (19.2) and 126.5 (19.9), respectively, and the mean (SD) DBP was 76.4 (10.6) and 74.0 (11.0), respectively. The correlation between RZS and the OD was 0.90 for SBP and 0.80 for DBP. The prevalence of high BP and hypertension and associations with albuminuria were similar when applying each of the five calibration methods. Robust regression was chosen for calibration, giving the following equations:(Equation is included in full-text article.)These equations had a higher R statistic than using calibration equations from the Coronary Artery Risk Development in Young Adults Study and the Heinz Nixdorf Recall Study. CONCLUSIONS: The JHS BP data have been calibrated using the above equations for use in future analyses.

A convenient method to verify the accuracy of oscillometric blood pressure monitors by the auscultatory method: A smartphone-based app.

It is recommended that oscillometric devices be calibrated by auscultation when first used, but this is difficult in practice. Here, we introduce a smartphone-based technique to verify the accuracy of blood pressure monitors (BPMs). We enrolled 99 consecutive subjects and tested 6 brands of BPMs in this study. During measurements of electronic oscillometric BPMs, Korotkoff sounds were simultaneously collected using a stethoscope head beneath a cuff connected to a smartphone, and an app named Accutension Stetho could then yield an auscultatory BP reading as a reference. Next, differences in BP between the different BPMs and Accutension Stetho were determined. The percentage of BP differences falling within 5, 10, and 15 mm Hg; the mean (MD) value; and the standard deviation (SD) of BP differences and deflation errors were analyzed among all the BPMs. We found that the percentages of SBP differences falling within 5 mm Hg of the 6 BPMs were 80%, 79%, 77%, 72%, 68%, and 63%, in turn. The deflation rates among the 6 BPMs were 2.23, 3.48, 6.10, 2.44, 3.66, and 4.85 mm Hg/beat, respectively. Deflation errors, which were defined as deflation prior to the end of the Korotkoff sounds, existed in 4 BPMs. In conclusion, Accutension Stetho could detect BP differences between oscillometric BPM readings and simultaneous auscultatory readings. Diastolic BP was overestimated when the device deflated prior to the end of the Korotkoff sounds. Using the app, it is possible to evaluate the accuracy of BPMs among the same subjects.

Blood pressure measurement by oscillometric and auscultatory methods in normotensive pregnant women / Evaluación de la presión arterial por los métodos oscilométrico e auscultatorio en embarazadas normotensas / Avaliação da pressão arterial pelos métodos oscilométrico e auscultatório em gestantes normotensas

ABSTRACT Objective: to compare blood pressure values obtained by auscultatory and oscillometric methods in different gestational periods, considering cuff width. Method: it is a cross-sectional and quasi-experimental study approved by the Research Ethics Committee. The sample consisted of 108 low-risk pregnant women. Blood pressure measurements were performed in gestational periods of 10-14, 19-22 and 27-30 weeks. Results: The oscillometric device presented values similar to the auscultatory method in systolic blood pressure, but overestimated diastolic blood pressure. Underestimation of blood pressure occurred when using the standard width cuff rather than the correct width cuff in both measuring methods. Conclusion: Verification of brachial circumference and use of adequate cuffs in both methods are indispensable to obtain reliable blood pressure values in pregnant women. We recommend performance of additional studies to evaluate diastolic blood pressure overestimation by the Microlife 3BTO-A.

RESUMEN Objetivo: Comparar los valores de presión arterial obtenidos por los métodos auscultatorio e oscilométrico en distintos períodos del embarazo, en función del ancho del manguito. Método: Se trata de un estudio transversal y cuasiexperimental aprobado por el Comité de Ética en Investigación. Se analizó una muestra compuesta por 108 embarazadas de bajo riesgo. Las medidas de presión arterial se obtuvieron en los períodos gestacionales de 10-14, 19-22 y 27-30 semanas. Resultados: El aparato oscilométrico presentó valores similares al método auscultatorio en la presión arterial sistólica, sin embargo sobreestimó la presión arterial diastólica. Hubo subestimación de la presión arterial al utilizar el manguito de anchura estándar en lugar del manguito de anchura adecuada, en los dos métodos de medida. Conclusión: La verificación de la circunferencia braquial y el uso de manguitos adecuados en los dos métodos son indispensables para obtener valores confiables de la presión arterial en embarazadas. Recomendamos que se realicen nuevos estudios para evaluar la sobreestimación de la presión arterial diastólica por el aparato Microlife 3BTO-A.

RESUMO Objetivo: Comparar os valores de pressão arterial, obtidos pelos métodos auscultatório e oscilométrico em diferentes períodos gestacionais, em função da largura do manguito. Método: Trata-se de um estudo transversal e quase-experimental aprovado pelo Comitê de Ética em Pesquisa. A amostra foi composta por 108 gestantes de baixo risco. As medidas de pressão arterial foram realizadas nos períodos gestacionais de 10-14, 19-22 e 27-30 semanas. Resultados: O aparelho oscilométrico apresentou valores similares ao método auscultatório na pressão arterial sistólica, porém superestimou a pressão arterial diastólica. Houve subestimação da pressão arterial ao utilizar o manguito de largura padrão ao invés do manguito de largura correta, nos dois métodos. Conclusão: A verificação da circunferência braquial e o uso de manguitos adequados nos dois métodos são indispensáveis para obter valores confiáveis da pressão arterial em gestantes. Recomendamos que novos estudos sejam realizados para avaliar a superestimação da pressão arterial diastólica pelo aparelho Microlife 3BTO-A.

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.

Office blood pressure measurement in the 21st century.

Measurement of blood pressure (BP) using the auscultatory method must follow specific rules and conditions to be reliable. Nonetheless, these requirements are often not followed in clinical practice, resulting in inaccurate BP readings. Simply replacing manual sphygmomanometers with an oscillometric device may still produce readings that are associated with a white coat effect. These limitations can be overcome by using an oscillometric sphygmomanometer that automatically records multiple readings with the patient resting quietly and alone, called automated office (AO)BP. AOBP produces office readings with a reduced white coat effect, which are also similar to the awake ambulatory BP. There is also evidence that AOBP is a better predictor of target organ damage than attended office BP. Furthermore, clinical outcome data support AOBP as having both a similar diagnostic threshold as awake ambulatory BP and a lower treatment target. Using AOBP in clinical practice simplifies recording office BP by not requiring an additional period of rest before activation of the device and by not having staff present during the actual measurements. Recent studies have reported that automatic BP measurements taken by staff in research studies with close adherence to guidelines using AOBP devices may produce similar readings to AOBP. Further research is needed to determine the best method for recording BP at systolic targets < 130 mm Hg and the relationship of office BP to ambulatory BP and home BP.

Validation of the professional device for blood pressure measurement Microlife WatchBP Office in adults and children according to the American National Standards Institute/Association for the Advancement of Medical Instrumentation/International Organization for Standardization standard.

OBJECTIVE: To assess the accuracy of the professional oscillometric blood pressure (BP) monitor Microlife WatchBP Office in adults and children according to the American National Standards Institute/Association for the Advancement of Medical Instrumentation/International Organization for Standardization (ANSI/AAMI/ISO) 81060-2:2013 standard. METHODS: Adults and children (aged 3-12 years) were recruited to fulfil the age, sex, BP and cuff distribution criteria of the ANSI/AAMI/ISO standard using the same-arm sequential BP measurement method. Three cuffs of the test device were used for arm circumferences of 14-22, 22-32 and 32-42 cm. RESULTS: A total of 115 participants were recruited and 88 were included in the analysis (51 adults and 37 children). For criterion 1, the mean±SD of the differences between the test device and reference BP was -1.0±7.0/-4.7±5.4 mmHg (systolic/diastolic). For criterion 2, the SD of the averaged BP differences between the test device and reference per participant was 5.15/4.77 mmHg (systolic/diastolic). CONCLUSION: The professional Microlife WatchBP Office BP monitor fulfilled the requirements of the ANSI/AAMI/ISO validation standard for adults and children and can be recommended for clinical use.

The airway hyperresponsiveness to methacholine may be predicted by impulse oscillometry and plethysmography in children with well-controlled asthma.

OBJECTIVE: Airway hyperresponsiveness (AHR) is a hallmark of asthma. Methacholine challenge test which is mostly used to confirm AHR is not routinely available. The aim of this study was to investigate the predictive values of fractional exhaled nitric oxide (FeNO), impulse oscillometry (IOS), and plethysmography for the assessment of AHR in children with well-controlled asthma. METHODS: 60 children with controlled allergic asthma aged 6-18 years participated in the study. FeNO measurement, spirometry, IOS, and plethysmography were performed. Methacholine challenge test was done to assess AHR. PC20 and dose response slope (DRS) of methacholine was calculated. RESULTS: Mild to severe AHR with PC20 < 4 mg/ml was confirmed in 31 (51.7%) patients. Baseline FeNO and total specific airway resistance (SRtot)%pred and residual volume (RV)%pred levels in plethysmography were significantly higher and FEV1%pred, FEV1/FVC%pred, MMEF%pred values were lower in the group with PC20 < 4 mg/ml. FeNO, SRtot%pred, and RV%pred levels were found to be positively correlated with DRS methacholine. The higher baseline FeNO, frequency dependence of resistance (R5-R20) in IOS and SRtot%pred in plethysmography were found to be significantly related to DRS methacholine in linear regression analysis (ß: 1.35, p = 0.046, ß: 4.58, p = 0.002, and ß: 0.78, p = 0.035, respectively). The cut-off points for FeNO and SRtot% for differentiating asthmatic children with PC20 < 4 mg/ml from those with PC20 ≥ 4 mg/ml were 28 ppb (sensitivity: 67.7%, specificity: 72.4%, p < 0.001) and 294.9% (sensitivity: 35.5%, specificity: 96.6%, p = 0.013), respectively. CONCLUSION: IOS and plethysmography may serve as reliable and practical tools for prediction of mild to severe methacholine induced AHR in otherwise "seemingly well-controlled'' asthma.

Validating Reference Equations for Impulse Oscillometry in Healthy Mexican Children.

BACKGROUND: The impulse oscillometry system (IOS) measures the impedance (Z) of the respiratory system, but proper interpretation of its results requires adequate reference values. The objectives of this work were: (1) to validate the reference equations for the IOS published previously by our group and (2) to compare the adjustment of new available reference equations for the IOS from different countries in a sample of healthy children. METHODS: Subjects were healthy 4-15-y-old children from the metropolitan area of Mexico City, who performed an IOS test. The functional IOS parameters obtained were compared with the predicted values from 12 reference equations determined in studies of different ethnic groups. The validation methods applied were: analysis of the differences between measured and predicted values for each reference equation; correlation and concordance coefficients; adjustment by Z-score values; percentage of predicted value; and the percentage of patients below the lower limit of normality or above the upper limit of normality. RESULTS: Of the 224 participants, 117 (52.3%) were girls, and the mean age was 8.6 ± 2.3 y. The equations that showed the best adjustment for the different parameters were those from the studies by Nowowiejska et al (2008) and Gochicoa et al (2015). The equations proposed by Frei et al (2005), Hellinckx et al (1998), Kalhoff et al (2011), Klug and Bisgaard (1998), de Assumpção et al (2016), and Dencker et al (2006) overestimated the airway resistance of the children in our sample, whereas the equation of Amra et al (2008) underestimated it. In the analysis of the lower and upper limits of normality, Gochicoa et al equation was the closest, since 5% of subjects were below or above percentiles 5 and 95, respectively. The study found that, in general, all of the equations showed greater error at the extremes of the age distribution. CONCLUSIONS: Because of the robust adjustment of the present study reference equations for the IOS, it can be recommended for both clinical and research purposes in our population. The differential adjustment of other equations underlines the need to obtain local reference values.

An anthropomorphic transhumeral prosthesis socket developed based on an oscillometric pump and controlled by force-sensitive resistor pressure signals.

While considering the importance of the interface between amputees and prosthesis sockets, we study an anthropomorphic prosthesis socket whose size can be dynamically changed according to the requirements of the residual limb. First, we introduce the structure and function of the anthropomorphic prosthesis socket. Second, we study the dynamic model of the prosthesis system and analyze the dynamic characteristics of the prosthesis socket system, the inputs of an oscillometric pump, and the control mechanism of force-sensitive resistor (FSR) pressure signals. Experiments on 10 healthy subjects using the designed system yield an average detection result between 102 and 112 kPa for the FSR pressure sensor and 39 and 41 kPa for the oscillometric pump. Results show the function of the FSR pressure signal in maintaining the contact pressure between the sockets and the residual limb. The potential development of an auto-adjusted socket that uses an oscillometric pump system will provide prosthetic sockets with controllable contact pressure at the residual limb. Moreover, this development is an attractive research area for researchers involved in rehabilitation engineering, prosthetics, and orthotics.

Diagnostic Accuracy Study of an Oscillometric Ankle-Brachial Index in Peripheral Arterial Disease: The Influence of Oscillometric Errors and Calcified Legs.

BACKGROUND: Peripheral arterial disease (PAD) is an indicator of widespread atherosclerosis. However, most individuals with PAD, in spite of being at high cardiovascular risk, are asymptomatic. This fact, together with the limitations of the Doppler ankle-brachial index (ABI), contributes to PAD underdiagnose. The aim of this study was to compare oscillometric ABI and Doppler ABI to diagnose peripheral arterial disease, and also to examine the influence of oscillometric errors and calcified legs on the PAD diagnoses. METHODS AND FINDINGS: We measured the ankle-brachial indexes of 90 volunteers (n = 180 legs, age 70 ± 14 years, 43% diabetics) using both oscillometer OMRON-M3 and Doppler. For concordance analyses we used the Bland and Altman method, and also estimated the intraclass correlation coefficient. Receiver Operating Characteristic Curves were used to examine the diagnostic performance of both methods. The ABI means were 1.06 ± 0.14 and 1.04 ± 0.16 (p = 0.034) measured by oscillometer and Doppler ABIs respectively, with limits of agreement of ± 0.20 and intraclass correlation coefficient = 0.769. Oscillometer yielded 23 "error" measurements, and also overestimated the measurements in low ankle pressures. Using Doppler as gold standard, oscillometer performance for diagnosis of PAD showed an Area Under Curve = 0.944 (sensitivity: 66.7%, specificity: 96.8%). Moreover, when considered calcified legs and oscillometric "error" readings as arteriopathy equivalents, sensitivity rose to 78.2%, maintaining specificity in 96%. The best oscillometer cut-off point was 0.96 (sensitivity: 87%, specificity: 91%, positive likelihood ratio: 9.66 and negative likelihood ratio: 0.14). CONCLUSION: Despite its limitations, oscillometric ABI could be a useful tool for the diagnosis of PAD, particularly when considering calcified legs and oscillometric "errors" readings as peripheral arterial disease equivalents.