No abstract available.
Airway Resistance* ; Oscillometry*

Background: Cuffless devices have been studied and developed in the past and in recent years products that employ photoplethysmography became available in the market. However, the vast majority of available product’s accuracy have not yet been studied. Objective: The main objective of this study was to compare a wristwatch device GT 103 to an oscillometric blood pressure device Omron HEM 7120 using the standards set by Association for the Advancement of Medical Instrumentation (AAMI) / The European Society of Hypertension (ESH) Working Group on Blood Pressure / International Organization for Standardization (ISO). Methods: This is a cross sectional study involving blood pressure measurements of 85 individuals using the test device (GT 103) and the reference device (Omron HEM 7120). Demographic characteristics such as age, arm circumference, diagnosis of hypertension, and treatment status were also reported. Sequential blood pressure measurements followed the prescribed steps of AAMI/ESH/ ISO. Paired measurements were statistically treated using the Paired T test. Mean differences of the paired measurements are reported in mean±SD, and proportions of blood pressure differences at ±5mmHg, ±10mmHg, and ±15mmHg are also reported. Results: The mean SBP difference of GT 103 and Omron 7120 was 1.5±20.5mmHg which is not significant (p=0.25) and mean DBP difference of 3±12.6 which is significant (p=0.00017). The result is in accordance with the criterion 1 of ANSI/AAMI/ISO 81060–2:2013 standard requirements (≤5±8 mmHg), but did not fulfil the criterion 2 which requires an SD of less than or equal to 6.47 for SBP and less than or equal to 6.90 mmHg for DBP. The proportion of paired blood pressure readings within ±5mmHg, ±10mmHg, and ±15mmHg were 19.61%, 36.08%, 45.1% for SBP and 30.98%, 56.07%, 69.8% for DBP. This shows that SBP and DBP measurements did not meet the requirement of AAMI/ESH/ISO. Conclusions and Recommendations This study showed that GT 103 did not fulfill the requirements for acceptable device accuracy. The use of the device for blood pressure measurement is still not recommended by the researcher. Future studies of other similar devices can be done to ensure accuracy of blood pressure measurement.
Hypertension ; Blood Pressure Determination ; Oscillometry

OBJECTIVE: To study the influence of disposable respiratory filter on the results of impulse oscillometery. METHODS: 90 healthy subjects were randomly selected and impulse oscillometery results were taken repeatedly through disposable respiratory filter and control device. All results were statistically analyzed. RESULTS: When using the disposable respiratory filter, respiratory impedance (Zrs) and resistance at all frequency (R5Hz-R35Hz) were significantly increased compared with the control device (P<0.01). The two measurements had a significant linear correlation (P<0.01) and a regression equation was established. The disposable respiratory filter did not exist in statistic difference to response frequency (Fres) and the elastic resistance (X5Hz-X15Hz) at all frequency(P>0.05). CONCLUSIONS The disposable respiratory filter can be used when testing pulmonary compliance, chest wall disease and obstruction outside the airway in impulse oscillometery system to avoid infection and ensure quality.
Airway Resistance ; Filtration/instrumentation* ; Humans ; Oscillometry

In order to eliminate the intrinsic noise due to special structure of the wrist, a new curve fitting algorithm based on singular value decomposition (SVD) was developed to increase the measurement accuracy. This algorithm could be subdivided into SVD and curve fitting algorithm (SCFA). SVD was used to extract the dominant component of oscillation waves at wrist. Then oscillation amplitudes of dominant component and cuff pressure were used to determine arterial blood pressure (ABP) with curve fitting algorithm. To test the performance of SCFA, 45 subjects underwent the ABP measurement with different methods. The correlation coefficient between the pooled blood pressure measured by the auscultation and those by SCFA was 0.96. Comparison the results of SCFA with those of traditional curve fitting algorithm (TCFA), we found that the proposed SCFA could be used to reduce the partial intrinsic interference and efficiently improve the accuracy of the ABP at wrist.
Algorithms ; Blood Pressure Determination ; instrumentation ; Humans ; Oscillometry ; instrumentation ; Wrist

The forced oscillation technique (FOT) is a noninvasive method for respiratory mechanics measurement. For the FOT, external signals (e.g. forced oscillations around 4-40 Hz) are used to drive the respiratory system, and the mechanical characteristic of the respiratory system can be determined with the linear system identification theory. Thus, respiratory mechanical properties and components at different frequency and location of the airway can be explored by specifically developed forcing waveforms. In this paper, the theory, methodology and clinical application of the FOT is reviewed, including measure ment theory, driving signals, models of respiratory system, algorithm for impedance identification, and requirement on apparatus. Finally, the future development of this technique is also discussed.
Algorithms ; Electric Impedance ; Oscillometry ; Physical Therapy Modalities ; Respiratory Mechanics

Blood pressure is an important physiological index that can reflect the function of the heart and blood vessels. Compared with other methods, oscillometric measurement has the advantages of strong noise immunity, simple operation and low cost, which is the most widely used technology for blood pressure measurement. In this paper, we reviewed and discussed the key technologies of measuring blood pressure, such as pre-processing method of oscillation envelope and blood pressure estimation technique. The latter include traditional wave method, waveform morphology method, the methods based on the model and machine learning. At last, we have a look forward to its future development direction.
Blood Pressure ; Blood Pressure Determination ; instrumentation ; Heart ; Oscillometry ; Technology

Mercury sphygmomanometer based on traditional auscultation method is widely used in primary medical institutions in China, but a large amount of blood pressure data can not be directly recorded and applied in scientific research analysis, meanwhile auscultation data is the clinical standard to verify the accuracy of non-invasive electronic sphygmomanometer. Focusing on this, we designed a miniature non-invasive blood pressure measurement and verification system, which can assist doctors to record blood pressure data automatically during the process of auscultation. Through the data playback function,the software of this system can evaluate and verify the blood pressure algorithm of oscillographic method, and then continuously modify the algorithm to improve the measurement accuracy. This study introduces the hardware selection and software design process in detail. The test results show that the system meets the requirements of relevant standards and has a good application prospect.
Auscultation ; Blood Pressure/physiology* ; Blood Pressure Determination ; Oscillometry ; Sphygmomanometers

PURPOSE: Exhaled nitric oxide (eNO) has been proposed as a non-invasive marker for airway inflammation in asthma. Pulmonary function tests have been widely used in the diagnosis and management of asthma. Airway hyperresponsiveness (AHR) is one of the major features in asthma and usually assessed by the methacholine challenge test. The purpose of the present study was to assess the possible relationship between eNO and pulmonary function/AHR in asthmatic children. METHODS: There were 121 asthmatic children and 81 controls in the study. The eNO level was measured, the methacholline challenge test, spirometry, impulse oscillometry (IOS) and assessment of their bronchodilator responses were performed on all subjects. RESULTS: The asthma group had a higher eNO value than the control group [28.3 (15-55.75) vs. 20 (12.35-39.7) ppb, P=0.015]. The eNO level correlated positively with dFEV1 (r=0.230, P= 0.001). It correlate inversely with dR5 (r=-0.149, P=0.036), eNO with PC20 (r=-0.318, P<0.001) and with FEF25-75 (r=-0.17, P=0.015), but not with FEV1. CONCLUSION: This study suggests that eNO values may reflect AHR, as well as airway inflammation, but not pulmonary function.
Asthma ; Child ; Humans ; Inflammation ; Methacholine Chloride ; Nitric Oxide ; Oscillometry ; Respiratory Function Tests ; Spirometry

OBJECTIVE: The importance of central blood pressure evaluation for cardiovascular risk stratification has been emphasized. The aim of this study is to evaluate whether brachial blood pressure obtained by the oscillometric method accurately reflects central blood pressure. METHODS: The subjects consisted of 84 consecutive patients with suspected coronary artery disease who underwent cardiac catheterization. Central blood pressure was invasively measured in the origin of the left subclavian artery by using the fluid-filled system, and at the same time, brachial blood pressure in the left upper arm was measured by the oscillometric method. RESULTS: No significant difference was found between central systolic pressure and brachial systolic pressure (144.49+/-18.84 mmHg vs. 142.44+/-14.96 mmHg, P=0.063). Bland-Altman analysis accounted for only a small bias of +2.25 mmHg, and the limits of agreement were 24.15 mmHg and -19.65 mmHg. Central diastolic pressure was significantly lower than brachial diastolic pressure (75.80+/-8.74 mmHg vs. 86.70+/-10.48 mmHg, P<0.001). Bland-Altman analysis showed a significant bias of -5.45 mmHg, and the limits of agreement were 2.83 mmHg and -13.73 mmHg. CONCLUSION: These results indicate that central systolic pressure can be directly estimated from brachial systolic pressure using the noninvasive oscillometric method and observed biases seem to remain within the practical range. However, use of the brachial diastolic pressure and pulse pressure measured by the noninvasive oscillometric method is doubtful in clinical practice because of their large biases.
Arm ; Bias (Epidemiology) ; Blood Pressure ; Cardiac Catheterization ; Cardiac Catheters ; Coronary Artery Disease ; Humans ; Oscillometry ; Subclavian Artery

PURPOSE: Measurement of forced expiratory volume in 1 second (FEV1) is usually difficult to obtain in children under six years of age because it requires active cooperation. This study evaluates the sensitivity of impulse oscillometry system (IOS) parameters for detecting airway obstruction in comparison with FEV1. METHODS: We studied 174 children who performed the lung function and methacholine challenge tests to diagnose asthma by IOS and spirometry. Children were divided into two subgroups according to their PC20, which is a parameter for bronchial sensitivity. We compared IOS parameters with FEV1 at the baseline, post-methacholine challenge, and evaluated their correlation. RESULTS: At the baseline, reactance at 5 Hz (X5) and resistance at 5 Hz (R5) significantly differed between the PC20 positive (PC20< or =16 mg/mL) group and PC20 negative (PC20>16 mg/mL) group; however, FEV1, FEV1% predicted, FEV1_Zs (Z score) did not differ. FEV1 is correlated with X5 (r=0.45, P<0.01) and R5 (r=-0.69, P<0.01). FEV1_Zs is also correlated with X5_Zs (r=-0.26, P<0.01) and R5_Zs (r=-0.31, P<0.01). After the methacholine challenge test, dose-response slopes in FEV1 and X5 significantly differed between the two subgroups (P<0.05). CONCLUSION: IOS parameters were more discriminative than FEV1 for detecting decreased baseline lung function between two subgroups and have a good correlation with FEV1.
Airway Obstruction ; Asthma ; Child ; Forced Expiratory Volume ; Humans ; Lung ; Methacholine Chloride ; Oscillometry ; Spirometry