Relative validity of an indirect calorimetry device for measuring resting energy expenditure and respiratory quotient.

BACKGROUND AND OBJECTIVES: Resting energy expenditure (REE) and respiratory quotient (RQ) are important for optimal nutritional care. The purpose of this study was to assess the accuracy and repeatability of an indirect calorimetry device (IIM-IC-100) in the measurement of REE and RQ in healthy Chinese adults. METHODS AND STUDY DESIGN: A total of 38 healthy adults (19 male and 19 female) aged 18-52 years (25±6 years) were enrolled in this study. REE and RQ were measured by IIM-IC-100 and by VO2000, alternately and in duplicate. RESULTS: There was a highly significant correlation between IIM-IC-100 REE and VO2000 REE (r=0.906, p<0.001), with mean IIM-IC-100 REE significantly higher than that of VO2000 (1475±269 vs 1394±313 kcal/d, p=0.002). Bland- Altman analysis revealed that the mean difference between IIM-IC-100 REE and VO2000 REE was 81.3 kcal/d, with limits of agreement of -185 to +347 kcal/d. There was no significant difference in RQ between the two devices. No significant differences were observed between the repeated measurements for both devices. Intrasubject coefficients of variation (CVs) of REE were smaller for IIM-IC-100 (5.8%) than for VO2000 (10.5%), while CVs of RQ were similar for IIM-IC-100 (7.2%) and VO2000 (6.9%). CONCLUSIONS: These preliminary data indicated that the IIM-IC-100 showed promise as an accurate and precise tool in the assessment of REE and RQ in healthy Chinese adults.

Late cardioprotection of exercise preconditioning against exhaustive exercise-induced myocardial injury by up-regulatation of connexin 43 expression in rat hearts.

OBJECTIVE: To investigate the expression of myocardium connexin 43 (Cx43) in late exercise preconditioning (LEP) cardioprotection. METHODS: Eight-week-old adult male Sprague Dawley rats were randomly assigned into four groups (n = 8). Myocardial injury was judged in accordance with serum levels of cTnⅠ and NT-proBNP as well as hematoxylin basicfuchsin picric acid staining of myocardium. Cx43 mRNA was detected by in situ hybridization and qualified by real-time fluorescence quantitative PCR. Cx43 protein was localized by immunohistochemistry and its expression level was determined by western blotting. RESULTS: The LEP obviously attenuated the myocardial ischemia/hypoxia injury caused by exhaustive exercise. There was no significant difference of Cx43 mRNA level between the four groups. Cx43 protein level was decreased significantly in group EE (P < 0.05). However, LEP produced a significant increase in Cx43 protein level (P < 0.05), and the decreased Cx43 protein level in exhaustive exercise was significantly up-regulated by LEP (P < 0.05). CONCLUSIONS: LEP protects rat heart against exhaustive exercise-induced myocardial injury by up-regulating the expression of myocardial Cx43.

Analysis of Forced Expiratory Flow Signals Using the New Luus-Jaakola Optimization Procedure.

OBJECTIVE: The aim of this study was to estimate forced vital capacity (FVC) by analyzing incomplete forced expiratory flow-time (FEFT) curves using the new Luus-Jaakola (NLJ) optimization procedure. METHODS: Complete FEFT curves from 90 subjects with and without respiratory disease were used to validate the method, and its application performance was evaluated by FEFT curves containing incomplete curves from nine obstructive patients. First, a lumped parameter model of the FEFT curve, taking FVC as one of the model parameters, is chosen. The 0- 1 s, 0-1.5 s, . . . , 0-6 s curves chosen from the accepted FEFT curves are, respectively, taken as the local system observations. Then, the NLJ optimization procedure was used to get the estimate of FVC (FVCest) by estimating the model parameters. Finally, FVCest was compared with the measured FVC (FVCmea). RESULTS: The difference between FVCest and FVCmea decreased with the lengths of observed curves increasing. When the lengths of observed curves reached 3 s, the mean difference (±SD) between FVCest and FVCmea was -11 ± 58 mL. Estimated FVC derived from the incomplete curves were close to FVC from accepted maneuvers. CONCLUSION: The method can be used to estimate FVC by analyzing an incomplete FEFT curve, providing the length of the curve is more than 3 s. SIGNIFICANCE: This method can help the subjects who cannot complete the forced expiratory maneuver to provide a reliable estimate of FVC and also can be used to analyze the unacceptable spirometry because of early termination of exhalation.

[Comparative Study on the Three Algorithms of T-wave End Detection: Wavelet Method, Cumulative Points Area Method and Trapezium Area Method].

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.

A new tonometric device for radial augmentation index and subendocardial viability ratio: potential use in health screening.

Augmentation index (AIx) and subendocardial viability ratio (SEVR) are widely accepted indices of wave reflection and myocardial oxygen demand relative to supply. This study aimed to validate a new tonometric device (IIM-2010A) for obtaining AIx and SEVR from radial artery. A total of 68 outpatients (32 men and 36 women) aged 20 to 76 years (44.7±16.6 years) recruited from a health screening center participated in the study. AIx was obtained from radial pressure using the HEM-9000AI and IIM-2010A devices, while SEVR was measured from carotid pressure with the tonometric method and from radial pressure by the IIM-2010A device. In a subgroup of 24 patients, the measurements of AIx and SEVR were repeated after an interval of 10 minutes. The correlation of radial AIx between the IIM-2010A and HEM-9000AI devices was highly significant (r=0.956, P<.01). Radial SEVR determined from IIM-2010A was also highly related to carotid SEVR (r=0.864, P<.01), although the value was about 13.1% lower. There was no statistically significant difference between the repeated measurements of both indices. The lower coefficient of variation (2.9% vs 4.3% for AIx, 3.3% vs 4.1% for SEVR) and higher intraclass correlation coefficient (0.96 vs 0.91 for AIx, 0.93 vs 0.86 for SEVR) of IIM-2010A confirmed better short-term reproducibility, compared with the HEM-9000AI device and carotid tonometry. The new tonometric device IIM-2010A is effective and reproducible in calculating radial AIx and SEVR and has potential use in health screening.

A low-pass differentiation filter based on the 2nd-order B-spline wavelet for calculating augmentation index.

The key point to calculate augmentation index (AIx) related to cardiovascular diseases is the precise identification of the shoulder point. The commonly used method for extracting the shoulder point is to calculate the fourth derivative of the pulse waveform by numerical differentiation. However, this method has a poor anti-noise capability and is computationally intensive. The aims of this study were to develop a new method based on the 2nd-order B-spline wavelet for calculating AIx, and to compare it with numerical differentiation and Savitzky-Golay digital differentiator (SGDD). All the three methods were applied to pulse waveforms derived from 60 healthy subjects. There was a significantly high correlation between the proposed method and numerical differentiation (r=0.998 for carotid pulses, and r=0.997 for radial pulses), as well as between the proposed method and the SGDD (r=0.995 for carotid pulses, and r=0.993 for radial pulses). In addition, the anti-noise capability of the proposed method was evaluated by adding simulated noise (>10Hz) on pulse waveforms. The results showed that the proposed method was advantageous in noise tolerance than the other two methods. These findings indicate that the proposed method can quickly and accurately calculate AIx with a good anti-noise capability.