Remote pulmonary function testing using a depth sensor
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Abstract:
We propose a remote non-invasive approach to Pulmonary Function Testing using a time-of-flight depth sensor (Microsoft Kinect V2), and correlate our results to clinical-standard spirometry results. Given point clouds, we approximate 3D models of the subject's chest, estimate the volume throughout a sequence and construct volume-time and flow-time curves for two prevalent spirometry tests: Forced Vital Capacity and Slow Vital Capacity. From these, we compute clinical measures, such as FVC, FEV1, VC and IC. We correlate automatically extracted measures with clinical spirometry tests on 40 patients in an outpatient hospital setting. These demonstrate high within-test correlations.Keywords:
Vital capacity
The pulmonary function records of 132 patients with cystic fibrosis followed for 5 to 7 years were reviewed. Changes in forced vital capacity, 1-sec forced expiratory volume, mean forced expiratory flow during the middle half of the forced vital capacity, and 1-sec forced expiratory volume as a percentage of forced vital capacity were examined. There was considerable variation in the rates of change, but the general pattern was consistent with a theory of exponential decline, mean forced expiratory flow during the middle half of the forced vital capacity showing the earliest and most dramatic changes. The pulmonary function of 33 patients (25 per cent) remained stable or improved throughout follow-up, possibly reflecting mild forms of lung disease or the efficacy of therapy. Twenty of these patients (15 per cent) maintained completely normal pulmonary function. The rate of decline in pulmonary function values, with progress of the disease, was steeper in the female patients.
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Lung function measurements play an essential role in early diagnosis and monitoring of bronchial asthma in children. For clinical evaluation, measurements are commonly compared to reference values. However, these reference values are calculated based on measurements performed in groups of mostly older children and young adults two or three decades ago. In the present, cross-sectional study, lung function measurements were performed in 518 children (241 boys and 277 girls; mean age 6.0+/-0.3 years) at a regular medical check prior to school enrollment. Spirometry was done using the MasterScreen IOS (Cardinal Health, Wurzburg). We recorded forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)), maximal expiratory flow (PEF), and maximal expiratory flow at 75, 50, and 25% of vital capacity (MEF(75), MEF(50), MEF(25)). We found that FEV(1) and FVC corresponded to reference values (101.0+/-14.9% and 95.4+/-13.6%, in boys and girls, respectively). In maneuvers satisfying ATS/ERS criteria (T(E) >1 sec), forced expiratory (parameters (PEF, MEF(50)) reached only 68.9+/-13.6 and 75.9+/-26.6% of reference values, in boys and girls, respectively). There was no significant correlation of lung function parameters to BMI. In conclusion, the hitherto reference values largely overestimate the maximal flow rates of preschool children performing a forced spirometry with T(E) >1 sec. At the age of 6, forced expiratory flow values are not (yet) impaired by an increased BMI. Standardized spirometry starting in preschool children allows closely evaluating the individual development of lung function during follow-up measurements.
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Lung function measured at work is used to make important employment decisions. Improving its quality will reduce misclassification and allow more accurate longitudinal interpretation over time.To assess the amount by which lung function (forced expiratory volume in 1 second [FEV1] and forced vital capacity [FVC]) values will be underestimated if recommended spirometry testing guidance is not followed.Lung function was measured in a population of workers. Knowledge of the final reproducible FEV1 and FVC for each worker allowed estimation of the underestimates that would have occurred if less forced manoeuvres than recommended had been performed.A total of 667 workers (661 males, mean age 43 years, range 18-66) participated. Among them, 560 (84%) achieved reproducible results for both FEV1 and FVC; 470 (84%) of these did so after three technically acceptable forced expiratory manoeuvres, a cumulative total of 533 after four, 548 after five, 557 after six, 559 after seven and 560 after eight blows. If only one (or first two) technically acceptable blow(s) had been performed, mean underestimates were calculated for FEV1 of 115.1 ml (35.4 ml) and for FVC of 143.4 ml (42.3 ml).In this study, reproducible spirometry was achievable in most workers. Not adhering to standards underestimates lung function by clinically significant amounts.
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Seventy-five adult asthmatic patients with clinical remission underwent spirometry. Only 8.3% of the subjects demonstrated normal spirometry. The others had reduced vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximum mid-expiratory flow rate (MMF) and peak flow rate (PEFR). This study demonstrates that asthma can cause irreversible airflow obstruction and there is a poor relationship between symptoms in asthmatics and their respiratory function test results.
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Tests of pulmonary function and radiographic imaging of the chest are the two key methods used in diagnostic evaluation of patients with pulmonary disease. Unlike blood pressure, acceptable normal values vary from person to person and from one demographic group to another. The first studies, in 1846, of spirometric assessment of forced vital capacity (FVC), the most basic pulmonary-function test, showed that normal values for vital capacity vary as a function of height and age.1 A few years later, it was shown that vital capacity was 6 to 12% lower in healthy black soldiers than in white or Native American . . .
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The accuracy of a simple, pneumatic, direct-recording spirometer suitable for office use was evaluated by comparing spirometry on a water-sealed, 13.5-liter, water-filled spirometer for 120 patients. Good correlation between the two spirometers was seen through a wide range of values for forced vital capacity, forced expiratory volume in one second, and forced expiratory flow during 25% to 75% of forced vital capacity, with coefficients of correlation being 988, 988, and 948, respectively. All correlations were significant. The pneumatic spirometer is accurate, simple to operate, and suitable for spirometry in the office and clinic. (JAMA240:2754-2755, 1978)
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The comparative ability to detect early abnormalities in smokers by commonly used lung function tests was studied. Sixty-five healthy male nonsmokers served as a reference group and provided standards for 1-sec forced expiratory volume, vital capacity, end-tidal spirometry, spirometric forced mid-and end-expiratory flows, single-breath diffusing capacity, static lung volumes (helium method), and single-breath N2 closing volume measurements, In the present series of 80 male smokers, the measurements of forced mid-expiratory flow and forced end-expiratory flow did not improve the ability of the more conventional indices, 1-sec forced expiratory volume and the ratio of 1-sec forced expiratory volume to vital capacity, to detect obstructive lung disease. In 71 smokers with normal 1-sec forced expiratory volume and ratio of 1-sec forced expiratory volume to vital capacity, the end-tidal spirometry, diffusing capacity, and residual volume indices revealed 14,20, and 21 per cent of abnormalities. respectively. The single-breath N2 closing volume test (Phase IV/vital capacity and slope of Phase III) detected the greatest number of subtle changes in lung function; this was abnormal in 32 per cent of smokers with normal conventional spirometry. In young or light smokers, Phase IV/vital capacity was more frequently increased than the slope of Phase III; an incerse trend was observed in older or heavier smokers. The single-breath N2 closing volume test also provided the greatest number of abnormal results when other indices were impaired in the same subjects.
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We aimed to ascertain the fit of the European Respiratory Society Global Lung Initiative 2012 reference ranges to contemporary Australasian spirometric data. Z-scores for spirometry from Caucasian subjects aged 4-80 years were calculated. The mean (SD) Z-scores were 0.23 (1.00) for forced expirtory volume in 1 s (FEV(1)), 0.23 (1.00) for forced vital capacity (FVC), -0.03 (0.87) for FEV(1)/FVC and 0.07 (0.95) for forced expiratory flows between 25% and 75% of FVC. These results support the use of the Global Lung Initiative 2012 reference ranges to interpret spirometry in Caucasian Australasians.
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The spirometry has been most valuable pulmonary function test and it defines pulmonary physiology. But the spirometry has not been widely used by general physicians in Japan. The spirometry is effort-dependent test, so, they seem to keep it at a distance. It's desirable that pulmonary function tests are effort-independent. We introduce some effort-independent pulmonary function tests and refer to analysis of exhaled breath condensate.
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