Objective To measure the activity energy expenditure(AEE) of healthy adults during level walking by using indirect calorimetry,and to analyze the characteristics and underlying influencing factors such as age and gender. Methods A total of 60 healthy adults aged 20-50 years (30 males and 30 femdes) participated in the study.All the subjects were divided into six groups by gender and age (the age span of each group was 10 years). The subjects were arranged to walk at speeds of 3.5,4.5,5.5km/h and run at 5.5,6.5,7.5km/h, respectively, on the treadmill. The resting energy expenditure ( REE ) and AEE were measured during walking and running at different speeds.There was a 5-minute rest among the test sessions. Results No difference in terms of AEE between the female and male at the same age ( P ＞ 0. 05 ). During 3.5km/h walking,AEE of 21-30 year-old females was lower than 31-40 yearold females and males( P ＜0.05 ) ;During 4.5km/h walking,AEE of 31-40 year-old females was higher than 21-30 yearold females and males and 41-50 year-old females; AEE of 21-30 year-old females was lower than 41-50 year-old males (P ＜ 0.05 ) ;During 5.5km/h walking,AEE of 31-40 year-old females was higher than 21-30 year-old females and males ( P ＜ 0. 05 ). During 6.5 km/h running, AEE of 31-40 year-old females was higher than 41-50 year-old females ( P ＜0.05), while during 7.5km/h running, AEE of 21-30 year-old males was higher than 41-50 year-old females (P ＜0.05 ). It was also found that the AEE of all groups except the 41-50 year-old females group was higher when walking at the speed of 5.5km/h than running at the same speed( P ＜ 0.05 ). Conclusions Age has more effect on REE and AEE than the gender. AEE of elder subjects is higher than that of the younger ones during walking, however, AEE of younger people increases faster than the elders during running. AEE of 31-40 year-old females is the highest in all groups both in walking and running. AEE in running is higher than in walking at the same speed.

In order to find the most suitable algorithm of T-wave end point detection for clinical detection, we tested three methods, which are not just dependent on the threshold value of T-wave end point detection, i. e. wavelet method, cumulative point area method and trapezium area method, in PhysioNet QT database (20 records with 3 569 beats each). We analyzed and compared their detection performance. First, we used the wavelet method to locate the QRS complex and T-wave. Then we divided the T-wave into four morphologies, and we used the three algorithms mentioned above to detect T-wave end point. Finally, we proposed an adaptive selection T-wave end point detection algorithm based on T-wave morphology and tested it with experiments. The results showed that this adaptive selection method had better detection performance than that of the single T-wave end point detection algorithm. The sensitivity, positive predictive value and the average time errors were 98.93%, 99.11% and (--2.33 ± 19.70) ms, respectively. Consequently, it can be concluded that the adaptive selection algorithm based on T-wave morphology improves the efficiency of T-wave end point detection.
Algorithms ; Electrocardiography ; Humans ; Wavelet Analysis

OBJECTIVEAssessing the reproducibility of a portable spirometer, including reproducibility of inter-observer and day-today.

METHODSLung ventilation function was performed in 22 healthy volunteers by two observers on the same day and repeated by the first observer after 24h.

RESULTSThe inter-observer and day-to-day intra-class correlation coefficients are all higher than 0.75. There are no significant difference between each other. Bland-Altman chart shows good limits of agreement between inter-observer and day-to-day, only scattered data are outside of the limits of agreement.

CONCLUSIONSThe portable spirometer shows good inter-observer and day-to-day reproducibility, and can be used for testing lung function in clinical.

Adult ; Female ; Humans ; Male ; Middle Aged ; Monitoring, Ambulatory ; instrumentation ; Observer Variation ; Reproducibility of Results ; Spirometry ; instrumentation

Indirect energy metabolism measurement is the gold standard for providing nutritional support for critical illness. The accuracy of the measurement data directly affects the outcome of the disease. In order to study the influence of sampling delay on the accuracy of energy metabolism measurement under mechanical ventilation, the Matlab/Simulink platform and respiratory electrical model were used for simulation and quantitative analysis. The results show that the error of indirect energy metabolism measurement increases with the increase of sampling delay, the error of sampling delay in mechanical ventilation mode is larger than that of spontaneous breathing, and the error of sampling delay in PCV mode of mechanical ventilation is larger than that in VCV mode. Therefore, there should be different sampling delay compensation strategies under severe mechanical ventilation and its different control modes.
Computer Simulation ; Critical Illness ; Energy Metabolism ; Humans ; Respiration, Artificial

A lung diffusion function detection system is designed. Firstly, the controllable collection of air, test gas source and calibration gas source was based on single-breath method measurement principle. Secondly, pulmonary diffusing capacity for carbon monoxide (D_lCO) was calculated by gas concentration measured by the non-dispersive infrared sensor to measure, the gas flow measured by the differential pressure sensor, and the temperature, humidity and atmospheric pressure sensors to test and evaluate the quantitative detection and evaluation of lung diffusion function. Moreover, a preliminary verification of the lung diffusion function detection system was implemented, and the results showed that the error of the lung carbon monoxide diffusion and the alveolar volume did not exceed 5%. Therefore, the system has high accuracy and is of great value for early screening and accurate assessment of COPD.
Carbon Monoxide ; Lung ; Pulmonary Diffusing Capacity/methods*