Study of heart rate variability to assess autonomic dysfunction in patients with chronic obstructive pulmonary disease of a tertiary care hospital of West Bengal: A cross-sectional comparative study

Background: Chronic obstructive pulmonary disease (COPD) is one of the major causes of morbidity and mortality throughout the world. COPD and its complications also lead to a large number of deaths every year in our country. Cardiac arrhythmias and sudden cardiac death are the major complications of COPD leading to death and disability. Such cardiac complications are often a result of autonomic dysfunction. Aims and Objectives: This study aims to find out the autonomic dysfunction in moderate COPD patients by comparing their heart rate variability (HRV) parameters with age and sex matched healthy controls. Materials and Methods: After obtaining approval from the Institutional Ethics Committee, 48 patients of moderate COPD and 54 healthy subjects were assessed and compared with respect to their HRV parameters which included Mean RR, Mean HR, SDNN, NN50, pNN50, root mean square of successive differences (RMSSD), high frequency (HF), low frequency (LF), LF/HF ratio, and SD2/SD1 ratio. Results: It was found that in comparison to healthy controls, patients of moderate COPD had significant alteration in the following HRV parameters – Mean HR (P: 0.001), RMSSD (P: 0.002), SDNN (P: 0.015), NN50 (P: 0.001), pNN50 (P: 0.000), HF (NU/normalized unit) [P: 0.033], HF (%) [P: 0.002], LF (NU/normalized unit) [P: 0.033], LF (%) [P: 0.012], and LF/HF (P: 0.033). Conclusion: As there is a significant alteration of several HRV parameters in moderate COPD patients, we conclude that HRV measurement may subserve as a simple and non-invasive tool to assess autonomic dysfunction in patients of COPD at the earliest.

Comparison of time domain heart rate variability parameters between smokers and non-smokers

Background: Cigarette smoking induced sympathetic overdrive is one of the major independent modifiable risk factors for cardiovascular mortality and morbidity. There is altered autonomic activity with increased adrenergic activity in chronic smoking which also predisposes to cardiovascular morbidity and mortality. There are several tests that can determine the Autonomic Activity. Among them, heart rate variability (HRV), especially the time domain parameters of it, is simple, easy to perform, and non-invasive test for diagnosing autonomic dysfunction in the smokers. Aims and Objectives: The aims of this study were to compare the time domain parameters of HRV in smokers and non-smokers. Materials and Methods: The present study was carried out at autonomic function laboratory and cardiovascular function laboratory, Department of Physiology, Government Medical College, Bhavnagar, among 200 subjects, out of which 100 were smokers and 100 were non-smokers, in age group of 20–50 years. Results: There was a significant increase in mean heart rate, blood pressure, and R-R interval in smokers as compared to the non-smokers. There was also a significant decrease in all time domain parameters of HRV which suggests profound sympathetic overdrive and a decrease in vagal tone due to the actions of nicotine presents in tobacco smoke. Conclusions: Cigarette smoking plays a major role in degradation and decreased function of autonomic nervous system.

Non-linear analysis of heart rate variability during deep breathing at 0.1 Hz frequency

Background: Heart rate variability (HRV) analysis is an important tool to assess the cardiac autonomic regulation in health and disease. Time-domain and frequency-domain analyses are linear methods that are traditionally used for HRV analysis. Application of non-linear methods in HRV analysis has been shown to provide additional information and has been found to be useful in predicting complications and mortality in cardiovascular disease conditions. HRV analysis during deep breathing is commonly used to assess the integrity and extent of the parasympathetic control of the heart. Aim and Objectives: This study aims to analyze the HRV during deep breathing at 0.1 Hz frequency, 6 breaths/minute using non-linear methods and to see whether they correlate with the time-domain measures of HRV. Materials and Methods: Twelve healthy volunteers performed deep slow breathing at 0.1 Hz frequency for 5 min following recorded prompts. In the time domain, mean heart rate (MHR), SDNN, RMSSD, and pNN50 during baseline and deep breathing were measured. In the non-linear domain, approximate entropy (AppEn), sample entropy (SampEn), and detrended fluctuation analysis DFA (?1) were calculated. The quantitative measures of the Poincare plot, namely, SD1, SD2, and SD2/SD1, which are known to provide linear information, were also estimated. Wilcoxon’s signed-rank test was used to compare the baseline parameters with those of deep breathing. Spearman’s correlation was used to assess the correlation between the parameters obtained from the different methods. Results: There was no significant change in the MHR, RMSSD, pNN50, and SD1 during 0.1 Hz deep breathing while SDNN, SD2, SD2/SD1, and DFA?1 showed a significant increase. Furthermore, 0.1 Hz breathing decreased the AppEn and SampEn measures of HRV. There was a strong correlation among SDNN, RMSSD, pNN50, SD1, SD2, SD2/SD1, and DFA?1, but there was no correlation between any of the above measures and the non-linear measures AppEn and SampEn. Conclusion: While the non-linear measure DFA?1 correlates well with time domain measures of HRV and the quantitative measures of the Poincare plot during 0.1 Hz breathing, AppEn and SampEn do not show such correlation. Instead, they decrease significantly when breathing is voluntarily controlled at 6 breaths/min.

Relationship between fragmented QRS wave with ventricular arrhythmia's incidence situation and heart rate variability in patients with old myocardial infarction / 中国综合临床

Objective:To explore the relationship between fragmented QRS complex and heart rate variability (HRV) and ventricular arrhythmia in patients with old myocardial infarction.Methods:From August 2018 to October 2019, 200 patients with old myocardial infarction were first treated in the Department of cardiac function examination of the First Affiliated Hospital of Hebei North University. The patients were divided into 99 cases of old myocardial infarction with fragmented QRS wave group and 101 cases of old myocardial infarction without fragmented QRS wave group according to the case bank data and conventional 12 lead ECG diagnosis in our hospital for the first time. Then, the 24-h ambulatory ECG reexamined within 1 year after discharge was retrospectively analyzed. The incidence of ventricular arrhythmia was compared between the two groups by χ 2 test. The difference of heart rate variability between the two groups was compared by rank sum test. Multiple logistic regression was used to analyze the value of different indexes of heart rate variability in the evaluation of fragmented QRS complex in old myocardial infarction. Drawing the receiver operating characteristic (ROC), and the area under the curve (AUC) was used to analyze the diagnostic accuracy of different indexes of heart rate variability in the broken QRS complex of old myocardial infarction. Results:According to the Lown classification of ventricular premature contraction, the number of positive ventricular arrhythmias in patients with Grade Ⅰ of ventricular premature contraction and Grade Ⅲ-Ⅴ of ventricular premature contraction in the old myocardial infarction fragmented QRS group was higher than that in the old myocardial infarction non fragmented QRS group (Grade Ⅰ of ventricular premature contraction: 54.5% (54/99)and 39.6%(40/101); χ 2=4.484, P<0.05;Grade Ⅲ-Ⅴ of ventricular premature contraction: 34.3% (34/99) and 9.9%(10/101); χ 2=17.406, P<0.05)). Ventricular premature contraction Grade 0 old myocardial infarction fragmented QRS group was lower than old myocardial infarction non fragmented QRS group (8.1% (8/99) and 48.5% (49/101); χ 2=37.995, P<0.05). The total number of positive cases of ventricular arrhythmia in the old myocardial infarction group with fragmented QRS wave was higher than that in the old myocardial infarction group without fragmented QRS wave (91.9% (91/99) and 51.5%(52/101); χ 2=57.146, P<0.05)). There was no significant difference in the number of positive ventricular arrhythmias between the old myocardial infarction fragmentation QRS group and the old myocardial infarction non fragmentation QRS group ( P>0.05). The standard deviation of NN intervals (SDNN) and the standard deviation of average NN intervals (SDANN) of HRV time domain indexes in the old myocardial infarction fragmented QRS group were higher than those in the old myocardial infarction non fragmented QRS Group (SDNN:143.00(122.00,166.00) vs. 110.00(95.00,130.50), Z=5.780, P<0.05; SDANN:112.00(100.00,136.00) vs. 96.00(76.00,118.50), Z=4.013, P<0.05). Multiple Logistics regression analysis results of HRV domain shows that HRV time domain SDNN and SDANN have diagnositic value in diagnosis fQRS after OMI(SDNN: OR=0.949, 95% CI:0.922-0.977, P<0.001; SDANN: OR=1.036, 95% CI:1.005-1.068, P=0.022). Area under ROC curve of HRV time domain SDNN and SDANN have particular diagnositic accuracy in diagnosis fQRS after OMI(SDNN: AUC 0.737, 95% CI 0.666-0.807, Sensitivity 0.818, Specificity 0.634; SDANN: AUC 0.664, 95% CI 0.587-0.741, Sensitivity 0.737, Specificity 0.673. 0.5<AUC<1). Conclusion:Fragmented QRS complex was positively correlated with the incidence and severity of ventricular arrhythmia in patients with old myocardial infarction, and positively correlated with time-domain indexes SDNN and SDANN of heart rate variability in patients with old myocardial infarction.

On-line moisture determination and optimization of drying process of Qiju Dihuang Pills by time-domain reflection method / 中草药

Objective: Taking Qiju Dihuang Pills (QDP) as the research object, time domain reflection method was used for real-time determination of moisture content in concentrated pills during drying process and optimization of the drying process parameters. Methods: The moisture model of the drying process of QDP was established by the relationship between the water, temperature, and the reflective signal value of time domain reflector. The effect of the drying process on the different thickness (8, 16, and 24 mm), different drying temperatures (30, 40, 50, 60, 70, 80, and 90℃) was investigated. Results: The moisture model of the drying process of QDP was measured by time domain reflection method as Y = 0.305 X-34.772 (r2 = 0.999); X = X(T)-(0.768 9 T-24.824 7) (T ≥ 30℃). The optimized process was as following: the process was dried at 60℃ to 13.8% moisture and then rising to 80℃, after being dried to 7.80%, cooled to 60℃ and dried to 5.0% target moisture. Conclusion: It is feasible to test the moisture content in the drying process of QDP by time domain reflection method. This method can be used to monitor and popularize the moisture content in the drying process of traditional Chinese medicine concentrated pills.

Application of heart rate variability in acupuncture research / 针刺研究

The measurement of heart rate variability (HRV) has the advantages of noninvasiveness and simple operation and is widely used in clinical trials and scientific research for assessing reactions of the autonomic nervous system. More and more studies on acupuncture also take HRV as an important index. In addition to the definition, origin, analytical methods, and significance of time domain and frequency domain parameters of HRV, we reviewed the situations of application of HRV to acupuncture research in recent years, analyzed the influence of acupuncture and sham acupuncture, different acupuncture methods, and different acupoints on HRV, and confirmed the role of HRV in reflecting the effect of acupuncture on the vagal and sympathetic systems. However, various interference factors for HRV measurement and diverse methods for data analysis may lead to great differences in the experimental results of HRV and the interpretation of parameters. Therefore, careful analysis is needed in future studies on acupuncture with HRV as an observation index.

Study on Pulse Recordings of College Students with Different Emotional States / 世界科学技术-中医药现代化

This paper was aimed to investigate the changes of pulses under different emotional states.Based on the emotional pulse theory of traditional Chinese medicine (TCM),with college students as the research object,through films to stimulate different emotional expressions (i.e.,calm,sad and happy) of college students,the pulse recordings of college students were acquired in this study.The time domain parameters of pulses of college students under three types of emotional states were extracted.The difference among three groups of time-domain parameters was calculated by nonparametric test.Based on the time-domain parameters,the Support Vector Machine (SVM) classifier was used to classify three types of emotional states.The results showed that there were significant differences in three groups of time domain parameters (h3/h1,t and As/(As+Ad)).And the average recognition rate of three types of emotion states was 74.25％ based on the time-domain parameters of the pulse recordings.It was concluded that the pulse parameters can provide objective reference for emotional changes.It can be used to identify emotional states.

Pharyngeal Swallowing Function in Elderly Patients with Asymptomatic Lacunar Infarction:Surface Electromy-ography Study / 中国康复理论与实践

Objective To observe the surface electromyography (sEMG) characteristics of pharyngeal swallowing muscles in different swallowing modes in asymptomatic lacunar infarction (LI) patients. Methods From January, 2015 to January, 2017, a total of 32 asymptom-atic LI patients (LI group) aged over 60 years were consecutively collected, and 30 normal old subjects matched with age and gender (nor-mal group) were also enrolled. The amplitudes of sEMG activity of infrahyoid muscles and submental muscles in different swallowing modes were recorded, and the root mean square (RMS) was analyzed. Results Significant difference was found in both muscle groups in dif-ferent swallowing modes in both groups (F>110.67, P0.05). In the 20 ml water swallowing mode, the RMS was lower in the submental muscles in the LI group than in the normal group (t=3.334, P0.05). In the 100 ml continuous drinking mode, the RMSs were significantly lower in both two muscle groups in LI group than in the normal group (t>3.118, P<0.01). Conclusion Swallow abilities decrease in asymptomatic LI. sEMG could be used to evaluate their swallowing function.

Surface Electromyography Studies of Pharyngeal Swallowing in Healthy Middle-aged and Old People / 中国康复理论与实践

Objective To observe the character of amplitude of myoelectric activity with surface electromyography (sEMG) on pharyn-geal swallowing in healthy middle-aged and elderly people. Methods From January, 2015 to January, 2016, 78 healthy subjects were separat-ed into middle-aged group (38~60 years old, n=38) and elderly group (61~82 years old, n=40). The amplitudes of sEMG activity of related muscles under different swallowing modes were recorded by sEMG technique and analysis system. The root mean square (RMS) was ana-lyzed. Results There was significant difference in RMS among different swallowing modes (F>105.120, P0.05). There was no difference between two groups in both muscles under relax and dry swallow (t0.05), and was different under water swallow and continuous drinking (t>2.700, P<0.05). Conclusion sEMG could be used for analyzing the characteristics of amplitude of myoelectric activity in healthy mid-dle-aged and elderly people during pharyngeal swallowing in different swallowing modes, that can be used to evaluate and screen swallow-ing and dysphagia in clinic.

Application of time domain reflectometry for determination of wate content in Xiangsha Yangwei pills / 中国中药杂志

Xiangsha Yangwei pill was selected as a model drug in this research, and time domain reflectometry (TDR) was used to determine the water content in the pill. The effects of five factors including the number of pill layers, pill packing density, atmospheric moisture, ambient temperature and the ratio of pill formula were investigated on water content. The results showed that the number of pill layers and ambient temperature had significant effects on water content of pills, while the pill packing density, atmospheric moisture and pill formula ratio had little effect on the determination of water content in pills. The reflection value was stable when 6 layers of pills were used. Under the condition of 25 ℃ and 45% relative humidity, the water content of pills ranged from 4.01% to 22.38%, showing good linear relationship between water content and reflection value, and the model equation was as follows: Y=0.279X－21.670 (R²=0.997 0). Verification experiment was used to explain the feasibility of this prediction model. The precision of the method complied with the methodology standard. It is concluded that TDR can be used in determination of water content in Xiangsha Yangwei pills. Additionally, TDR, as a new way to quickly and efficiently determine the water content, has a prospect application in the processing of traditional Chinese medicine pharmacy, especially for concentrated pill.

The role of pulse oximetry plethysmographic waveform monitoring as a marker of restoration of spontaneous circulation:a pilot study / 中华危重病急救医学

ObjectiveTo investigate the feasibility of using pulse oximetry plethysmographic waveform (POP) to identify the restoration of spontaneous circulation (ROSC) during cardiopulmonary resuscitation (CPR).Methods An observational research was conducted. A porcine model of ventricular fibrillation (VF) arrest was reproduced. After 3 minutes of untreated VF, animals received CPR according to the latest CPR guidelines, providing chest compressions to a depth of 5 cm with a rate of 105 compressions per minute and instantaneous mechanical ventilation. After 2 minutes of CPR, animals were defibrillated with 100 J biphasic, followed by continuous chest compressions. Data of hemodynamic parameters, partial pressure of end-tidal carbon dioxide (PETCO2) and POP were collected. The change in POP was observed, and the characteristics of changes of the waves were recorded during the peri-CPR period using the time and frequency domain methods.Results VF was successfully induced in 6 pigs, except 1 death in anesthesia induction period.① After VF, invasive blood pressure waveform and POP of the animals disappeared. PETCO2 was (18.83±2.71) mmHg (1 mmHg=0.133 kPa), and diastolic arterial pressure was (23.83±5.49) mmHg in compression stage. Animals attained ROSC within 1 minute after defibrillation, with PETCO2 [(51.83±9.35) mmHg] and diastolic arterial pressure [(100.67±10.97) mmHg] elevated significantly compared with that of compression stage (t1 = 8.737,t2 = 25.860, bothP = 0.000), with appearance of arterial blood pressure waveform.② Characteristic changes in POP were found in all experimental animals. During the stages of induced VF, compression, ROSC, and compression termination, POP showed characteristic waveform changes. POP showed disappearance of waveform, regular compression wave, fluctuation hybrid and stable pulse wave in time domain method; while in the frequency domain method waveform disappearance, single peak of compression, double or fusion peak and single peak of pulse were observed.Conclusion Analysis of POP using time and frequency domain methods could not only quickly detect cardiac arrest, but also show a role as a feasible, non-invasive marker of ROSC during CPR.

Foveal Thickness between Stratus and Spectralis Optical Coherence Tomography in Retinal Diseases

PURPOSE: To compare the foveal thickness (FT) parameters measured by Stratus optical coherence tomography (OCT) and Spectralis OCT in various retinal diseases and to construct conversion formulas between the two types of OCT devices. METHODS: We examined 366 consecutive patients (475 eyes) with retinal diseases and 13 normal controls (13 eyes). The patients were categorized into eight retinal disease groups. The mean amount and distribution of foveal thickness differences (FTD) measured by Stratus and Spectralis OCT were determined, and conversion formulas were constructed for Stratus OCT FT from Spectralis OCT FT for each retinal disease group. RESULTS: Among retinal diseases, the mean FTD was significantly larger in exudative age-related macular degeneration (AMD) patients (mean +/- SD, 94.0 +/- 55.0 microm) compared to normal subjects (66.2 +/- 11.7 microm; p < 0.0001). The proportion of eyes with a mean FTD outside 1.96 standard deviations of normal subject FTD was greatest in the exudative AMD (50.0%) group and smallest in the macular hole (18.2%) group. The predicted FTs obtained through the conversion formulas showed lower variance than the actual FTD values, especially in the exudative AMD group. The prediction line for exudative AMD deviated most from that of normal subjects. CONCLUSIONS: FTD shows diverse values and variances among various retinal diseases, especially in exudative AMD, which indicates that Stratus OCT FT cannot be predicted from Spectralis OCT FT by FTD value alone. We constructed statistically significant conversion formulas, which provided more reliable methods to predict Stratus OCT-measured FT from Spectralis OCT measurements for different retinal disease groups.

Comparison of the Efficacy between Time and Spectral Domain Optical Coherence Tomography for the Identification of Vitreomacular Interface

PURPOSE: To compare the efficacy of time domain (TD) and spectral domain (SD) optical coherence tomography (OCT) in determining vitreomacular interface (VMI). METHODS: VMIs were evaluated with TD and SD OCT images crossing the fovea horizontally in 69 eyes (mean age 52.7 +/- 15.4 years) and were classified as follows: (1) no vitreomacular separation (VMS), (2) incomplete VMS, and (3) unknown. RESULTS: In TD OCT, no VMS was observed in 2 eyes (2.9%), incomplete VMS in 2 eyes (2.9%), and unknown in 65 eyes (94.2%). In SD OCT, no VMS was observed in 31 eyes (45.0%), incomplete VMS in 13 eyes (18.8%), and unknown in 25 eyes (36.2%). In 31 eyes with no VMS on SD OCT, 29 eyes (93.5%) presented unknown on TD OCT (p<0.0001). In 13 eyes with incomplete VMS on SD OCT, 2 eyes (15.4%) showed incomplete VMS and 11 eyes (84.6%) showed unknown on TD OCT (p<0.0001). TD OCT was also non-informative in all 25 eyes with unknown on SD OCT. CONCLUSIONS: SD OCT allows better visualization of VMI than TD OCT, especially in patients with no VMS.

Quantitative measurement of macular ganglion cell complex thickness by spectral domain optical coherence tomography / 中华实验眼科杂志

Background Glaucoma is primarily characterized by the damage of retinal ganglion cells.The macular ganglion cell complex (GCC)thickness can be quantitatively measured using spectral domain optical coherence tomography(SD-OCT). Objective This clinical study was to explore the macular GCC thickness change in primary open-angle glaucoma (POAG) patient with SD-OCT. Methods A serial case-controlled study was designed.A total 101 eyes of 101 POAG patients and 41 normal eyes of 41 age- and refract power-matched normal subjects were cnrolled in the study.POAG patients were assigned to normal perimetry POAG group,early stage POAG group,advanced POAG group and late stage POAG group.Average macular GCC thickness(GCC-Avg),superior GCC thickness(GCC-Sup) and inferior GCC thickness (GCC-Inf)of subjects were measured by SD-OCT and compared among POAG patients and normal controls.Peripapillary retinal nerve fiber layer(RNFL) thickness was measured with time domain OCT(TD-OCT).The correlation between GCC thickness with RNFL thickness or mean deviation(MD) of perimetry were evaluated and analyzed.Informed consent was obtained from each patient prior to entering this study.Results GCC-Avg thickness,GCC-Sup thickness and GCC-Inf thickness were significantly decreased in the normalperimetry POAG group and early stage POAG group compared with the normal control group (GCC-Avg:t =5.411,10.247,P ＜ 0.01 ; GCC-Sup:t =6.171,9.484,P＜ 0.01 ; GCC-Inf:t =5.281,8.592,P ＜ 0.01 ).Also,GCC-Avg thickness,GCC-Sup thickness and GCC-Inf thickness were significantly decreased in the advanced POAG group compared with the early stage POAG group ( GCC-Avg:t =4.246,P＜0.01 ; GCC-Sup:t - 2.419,P - 0.019 ; GCC-Inf:t =4.636,P＜0.01 ),and GCC-Avg thickness,GCC-Sup thickness and GCC-Inf thickness were significantly decreased in the late stage POAG group compared with the advanced POAG group (GCC-Avg:t=2.095,P=0.040;GCC-Sup:t=2.756,P＜0.01:GCC-Inf:t =2.018,P =0.040 ).The positive correlations were seen between GCC-Avg thickness,GCC-Sup thickness,GCC-Inf thickness and RNFL-Avg thickness,RNFL-Sup thickness,RNFL-Inf thickness respectively( r =0.802,0.825,0.856,P ＜ 0.01 ).MD value of perimetry was positive correlated with GCC-Avg thickness in POAG patients ( r =0.601,P ＜ 0.01 ). Conclusions SD-OCT can quantitatively measure and differentiate the GCC thickness in POAG patients.The GCC thickness gradually decreases with the development of POAG.There exist a well correlation between visual field defect and RNFL thinning.

A Formula to Predict Spectral Domain Optical Coherence Tomography (OCT) Retinal Nerve Fiber Layer Measurements Based on Time Domain OCT Measurements

PURPOSE: To establish and validate a formula to predict spectral domain (SD)-optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) thickness from time domain (TD)-OCT RNFL measurements and other factors. METHODS: SD-OCT and TD-OCT scans were obtained on the same day from healthy participants and patients with glaucoma. Univariate and multivariate linear regression relationships were analyzed to convert average Stratus TD-OCT measurements to average Cirrus SD-OCT measurements. Additional baseline characteristics included age, sex, intraocular pressure, central corneal thickness, spherical equivalent, anterior chamber depth, optic disc area, visual field (VF) mean deviation, and pattern standard deviation. The formula was generated using a training set of 220 patients and then evaluated on a validation dataset of 105 patients. RESULTS: The training set included 71 healthy participants and 149 patients with glaucoma. The validation set included 27 healthy participants and 78 patients with glaucoma. Univariate analysis determined that TD-OCT RNFL thickness, age, optic disc area, VF mean deviation, and pattern standard deviation were significantly associated with SD-OCT RNFL thickness. Multivariate regression analysis using available variables yielded the following equation: SD-OCT RNFL = 0.746 x TD-OCT RNFL + 17.104 (determination coefficient [R2] = 0.879). In the validation sample, the multiple regression model explained 85.6% of the variance in the SD-OCT RNFL thickness. CONCLUSIONS: The proposed formula based on TD-OCT RNFL thickness may be useful in predicting SD-OCT RNFL thickness. Other factors associated with SD-OCT RNFL thickness, such as age, disc area, and mean deviation, did not contribute to the accuracy of the final equation.

Ultrasonic guided waves in long bones based on finite-difference time-domain method / 医用生物力学

Objective To discuss the effects of elastic modulus on propagation characteristics of ultrasonic guided waves in long bones based on finite-difference time-domain (FDTD) method, so as to provide the theoretical references for evaluating bone fatigue damage at the early stage. Methods A cylinder was used to model the long bone, and FDTD method was used to simulate the long bone with different elastic modulus. Then, the propagation characteristics of different guided wave modes were calculated, including the phase velocity, the group velocity, the central frequency and the energy. ResultsThe elastic modulus of long bones was closely related with the propagation characteristics of ultrasonic guided waves. The phase velocity, the group velocity, the central frequency and the energy were all reduced with the decrease in elastic modulus, and the variation tendency of L(0,5) mode was the most obvious. Conclusions The propagation of ultrasound guided waves can reflect the variation of elastic modulus of long bones, which provides a possible way to evaluate the fatigue damage at the early stage in long bones.

Correlation of average RNFL thickness using the STRATUS OCT with the perimetric staging of glaucoma

Objective@#To determine the correlation between average peripapillary retinal nerve fiber layer (RNFL) thickness measured with time domain optical coherence tomography (TD-OCT) in normal and glaucoma eyes. @*Methods@#This was a cross-sectional study of 281 eyes randomly selected from a previous study. Assessment of glaucomatous damage was done by glaucoma specialists who based their diagnosis on the visual field tests and optic disc photos, independent of OCT results. Eyes were classified into the following groups: normal, mild, moderate, or severe glaucoma. Severity of glaucoma was based on visual field abnormalities following a modified HodappAnderson-Parish criteria for staging. Average RNFL thickness of normal and glaucoma subgroups, as measured with STRATUS–OCT, were analyzed using single ANOVA test. Association between average RNFL thickness and severity of glaucomatous visual field loss was evaluated using the Pearson’s correlation coefficient analysis. @*Results@#183 eyes had no glaucoma; 27 had mild, 32 had moderate, and 39 had severe glaucoma. Mean average peripapillary RNFL thickness (μm) in the normal, mild, moderate, and severe glaucoma groups were 98.05(±13.46), 76.27(±11.79), 76.42(±16.01), and 56.17(±14.92) respectively. Significant differences were seen in the average RNFL thickness among the groups (P<0.05), except in eyes with mild to moderate glaucoma. A moderately strong correlation of -0.57 (P<0.05) was observed between average RNFL thickness and the stage of glaucoma. @*Conclusion@#TD-OCT showed moderately strong correlation between the average RNFL thickness and perimetric stages of glaucoma. Average RNFL thickness is a good parameter to discriminate normal from glaucoma eyes.

The correlation between synchronic variation of heart rate and blood pressure and coronary artery leslons / 中国医师进修杂志

ObjectiveTo investigate the significance of synchronic heart rate variation(HRV) and blood pressure variation(BPV) in the evaluation of coronary artery disease(CAD).MethodsOne hundred and three patients who received coronary artery angiography were divided by the lesion degree into occlusion group (28 cases with more than 1 complete-occlusion coronary artery),non-occlusion group (45 cases with more than 1 coronary artery stenosis ≥50％ but without complete-occlusion) and control group (30 cases without stenosis ≥50％).Occlusion group and non-occlusion group were divided by lesion location into left anterior descending (LAD) lesion (32 cases),left circumflex ( LCF ) lesion (23 cases ) and right coronary artery(RCA) lesion (18 cases).And these two groups were also divided by lesion branch number into 1 lesion branch (23 cases),2 lesion branches (19 cases) and 3 lesion branches(31 cases).The time domain indexes of HRV were detected and calculated by 24 h dynamic blood pressutre and ECG,including standard deviation of normal number of R-R intervals (SDNN),standard deviation of per 5 min average normal R-R intervals(SDANNind),24 h average of standard deviation of per 5 min normal R-R intervals(SDNNind),root mean square of standard deviation of adjacent normal R-R intervals (rMSSD),and percentage of the difference of adjacent normal R-R intervals ＞ 50 ms (PNN50).And indexes of BPV were detected,including daytime systolic pressure standard deviation (dSSD),daytime diastolic pressure standard deviation (dDSD) and nighttime systolic blood pressure standard deviation (nSSD).The correlations between synchronic HRV and BPV and different coronary artery lesions were analyzed.ResultsSDNN,SDANNind significantly decreased and dSSD obviously increased with the aggravation of coronary stenosis,and there was statistical significance[ ( 115 ± 35 ) ms vs.(98 ± 25 ) ms vs.( 78 ± 28 ) ms,( 100 ± 30) ms vs.( 86 ± 23 ) ms vs.( 70 ± 29 )ms,(14 ± 3) mm Hg (1 mm Hg=0.133 kPa) vs.(20±4) mm Hg vs.(28±2) mm Hg](P＜0.05).rMSSD and PNN50 decreased,dDSD and nSSD increased with the aggravation of coronary artery stenosis,but there was no statistical significance (P＞0.05).SDNN and SDANNind in patients with LAD lesion and LCX lesion were significantly lower than those in control group,and dSSD was obviously higher than that in control group (P ＜ 0.01 or ＜ 0.05 ).SDANNind,rMSSD,PNN50,dDSD and nSSD in patients with LAD lesion and LCX lesion had no significant difference compared with those in control group (P ＞ 0.05 ).SDNN,SDANNind,SDNNind,rMSSD,PNN50,dSSD,dDSD and nSSD in patients with RCA lesion had no statistical significance compared with those in control group ( P ＞ 0.05 ).All the indexes of HRV tended to descend and indexes of BPV trended to raise with the increasing number of coronary artery lesion branches.But only the changes of SDNN,SDANNind,SDNNind,rMSSD,PNN50 and dSSD had statistical significance (P ＜ 0.05).Conclusions The more significantly HRV decreases and dSSD increases in patients with coronary artery disease,the more serious the coronary artery stenosis is and the wider the lesions are.The lesions are commonly located in LAD.It has certain guiding value for the evaluation of coronary artery diseases.

Comparison of Retinal Nerve Fiber Layer Thickness between Stratus and Spectralis OCT

PURPOSE: To compare the peripapillary retinal nerve fiber layer (RNFL) thickness of normal patients and those with various glaucoma diseases by time domain (Stratus) and spectral domain (Spectralis) optical coherence tomography (OCT). METHODS: The RNFL thickness as measured by the Stratus and Spectral OCT was compared (paired t-test). The relationship and agreement of RNFL thickness between the two OCT modalities were evaluated by Pearson correlation, Bland-Altman plot, and area under the receiver operating characteristic curve. RESULTS: Two-hundred seventeen eyes of 217 patients, including twenty-four normal eyes, ninety-one glaucoma suspects, seventy-six normal tension glaucoma cases, and twenty-six primary open angle glaucoma cases (POAG) were analyzed. The peripapillary RNFL thicknesses as measured by Stratus OCT were significantly greater than those measured by Spectralis OCT. However, in quadrant comparisons, the temporal RNFL thickness obtained using Stratus OCT were significantly less than those obtained using Spectralis OCT. Correlations between RNFL parameters were strong (Pearson correlation coefficient for mean RNFL thickness = 0.88); a high degree of correlation was found in the POAG group. Bland-Altman plotting demonstrated that agreement in the temporal quadrant was greater than any other quadrant. CONCLUSIONS: Both OCT systems were highly correlated and demonstrated strong agreement. However, absolute measurements of peripapillary RNFL thickness differed between Stratus OCT and Spectralis OCT. Thus, measurements with these instruments should not be considered interchangeable. The temporal quadrant was the only sector where RNFL thickness as measured by Spectralis OCT was greater than by Stratus OCT; this demonstrated greater agreement than other sectors.

Simulation and measurement of acoustic field by HIFU transducer / 国际生物医学工程杂志

Objective In the treatment of tumor with high intensity focused ultrasound (HIFU),the acoustic pressure distribution determines the safety and reliability of HIFU.It is necessary to predict the acoustic field produced by HIFU transducer.Methods To analyze the acoustic pressure distribution of HIFU generated by different excitation frequency and variable incentive power,comparison was made between the acoustic pressure simulated by finite difference time domain (FDTD) method and the ones measured by experiments.ResultsThe resultsshowed that the pressureat focalpoint increasedwiththe increasing of excitation power,while the change in the focal length was negligible.The focal point moved towards the transducer with the frequency increasing until the maximum sound pressure was gained at the resonant frequency (RF).Conclusion The simulation results are consistent with the experiment results,indicating that the acoustic fields can be predicted by simulation.