Objective The purpose of this study was to clarify the differences in physiological properties of the airways between asthma and COPD using an impulse oscillation system (IOS). Patients and Methods Subjects comprised 95 stable COPD patients, 52 never-smoker asthma patients and 29 healthy never-smokers >60 years old, all matched for age, in whom respiratory impedance was examined by IOS. Results In both asthma and COPD patients, a significant increase in respiratory resistance (Rrs5) and more negative value of respiratory reactance (Xrs5) at 5 Hz of oscillatory frequency with an increase in resonant frequency (fres) were observed when compared with healthy never-smokers. In asthma, a significant increase in respiratory resistance at 20 Hz (Rrs20) was also observed when compared with healthy never-smokers and COPD. The increases in Rrs5 and relative changes of Xrs5 to more negative were remarkable with increasing severity of COPD. On the other hand, among patients with asthma, these changes in Rrs5 and Xrs5 were also observed in asthmatics with normal FEV1/FVC. Interestingly, Xrs5 showed further changes to more negative in expiration of tidal breath in severe COPD, whereas no significant changes in Xrs5 to more negative in expiration was observed in healthy never-smokers and asthmatics with and without normal FEV1/FVC. Conclusion IOS may be useful for detecting pathophysiological changes of respiratory system in accordance with severity of COPD and even in asthmatics with normal FEV1/FVC. The larger within-breath changes of Xrs5 to more negative in severe COPD may represent easy collapsibility of small airways in expiration of tidal breath. These properties may help to analyze airway mechanics and to identify abnormalities of the airways that cannot be found by spirometry alone.

Peer reviewed article authored by (Kitaguchi Y, Komatsu Y, Fujimoto K, Hanaoka M, Kubo K). Read article or submit your manuscript for publishing.

A small-size, high-precision fiber Bragg grating interrogator was developed for continuous plethysmograph monitoring. The interrogator employs optical edge filters, which were integrated with a broad-band light source and photodetector to demodulate the Bragg wavelength shift. An amplifier circuit was designed to effectively amplify the plethysmograph signal, obtained as a small vibration of optical power on the large offset. The standard deviation of the measured Bragg wavelength was about 0.1 pm. The developed edge filter module and amplifier circuit were encased with a single-board computer and communicated with a laptop computer via Wi-Fi. As a result, the plethysmograph was clearly obtained remotely, indicating the possibility of continuous vital sign measurement.

In this paper, we propose a blood pressure calculation and associated measurement method that by using a fiber Bragg grating (FBG) sensor. There are several points at which the pulse can be measured on the surface of the human body, and when a FBG sensor located at any of these points, the pulse wave signal can be measured. The measured waveform is similar to the acceleration pulse wave. The pulse wave signal changes depending on several factors, including whether or not the individual is healthy and/or elderly. The measured pulse wave signal can be used to calculate the blood pressure using a calibration curve, which is constructed by a partial least squares (PLS) regression analysis using a reference blood pressure and the pulse wave signal. In this paper, we focus on the influence of individual differences from calculated blood pressure based on each calibration curve. In our study, the calculated blood pressure from both the individual and overall calibration curves were compared, and our results show that the calculated blood pressure based on the overall calibration curve had a lower measurement accuracy than that based on an individual calibration curve. We also found that the influence of the individual differences on the calculated blood pressure when using the FBG sensor method were very low. Therefore, the FBG sensor method that we developed for measuring the blood pressure was found to be suitable for use by many people.

Background: The syndrome of combined pulmonary fibrosis and emphysema (CPFE) is a recently described entity associating upper-lobe emphysema and lower-lobe fibrosis. We sought to evaluate differences in pulmonary function between CPFE patients with and without airflow obstruction. Subjects and methods: Thirty-one CPFE patients were divided into two groups according to the presence or absence of irreversible airflow obstruction based on spirometry (forced expiratory volume in 1 second/forced vital capacity <70% following inhalation of a β₂-agonist) as follows: CPFE patients with airflow obstruction (CPFE OB⁺ group, n=11), and CPFE patients without airflow obstruction (CPFE OB^– group, n=20). Pulmonary function, including respiratory impedance evaluated using impulse oscillometry and dynamic hyperinflation following metronome-paced incremental hyperventilation, was retrospectively analyzed in comparison with that observed in 49 chronic obstructive pulmonary disease (COPD) patients (n=49). Results: In imaging findings, low-attenuation-area scores on chest high-resolution computed tomography, representing the degree of emphysema, were significantly lower in the CPFE OB^– group than in the CPFE OB⁺ and COPD groups. In contrast, the severity of pulmonary fibrosis was greater in the CPFE OB^– group than in the CPFE OB⁺ group. In pulmonary function, lung hyperinflation was not apparent in the CPFE OB^– group. Impairment of diffusion capacity was severe in both the CPFE OB^– and CPFE OB⁺ groups. Impulse oscillometry showed that respiratory resistance was not apparent in the CPFE OB^– group compared with the COPD group, and that easy collapsibility of small airways during expiration of tidal breath was not apparent in the CPFE OB⁺ group compared with the COPD group. Dynamic hyperinflation following metronome-paced incremental hyperventilation was significantly greater in the COPD group than in the CPFE OB^– group, and also tended to be greater in the CPFE OB⁺ group than in the CPFE OB^– group. Conclusion: The mechanisms underlying impairment of physiological function may differ among CPFE OB⁺ patients, CPFE OB^– patients, and COPD patients. CPFE is a heterogeneous disease, and may have distinct phenotypes physiologically and radiologically.

This paper describes and verifies a non-invasive blood glucose measurement method using a fiber Bragg grating (FBG) sensor system. The FBG sensor is installed on the radial artery, and the strain (pulse wave) that is propagated from the heartbeat is measured. The measured pulse wave signal was used as a collection of feature vectors for multivariate analysis aiming to determine the blood glucose level. The time axis of the pulse wave signal was normalized by two signal processing methods: the shortest-time-cut process and 1-s-normalization process. The measurement accuracy of the calculated blood glucose level was compared with the accuracy of these signal processing methods. It was impossible to calculate a blood glucose level exceeding 200 mg/dL in the calibration curve that was constructed by the shortest-time-cut process. In the 1-s-normalization process, the measurement accuracy of the blood glucose level was improved, and a blood glucose level exceeding 200 mg/dL could be calculated. By verifying the loading vector of each calibration curve to calculate the blood glucose level with a high measurement accuracy, we found the gradient of the peak of the pulse wave at the acceleration plethysmogram greatly affected.