Long Sudarshan Kriya Yoga enhances cardiovascular and respiratory synchronization: An observational study

BACKGROUND

Sudarshan Kriya Yoga (SKY - a rhythmic cyclic breathing) is known to produce several physiological changes in human body. Earlier it has been reported that SKY improves cardiovascular modulations, namely increase in heart rate variability.

OBJECTIVE

To observe the synchronization in oscillatory modulations in cardiac autonomic tone and ventilatory exchange during Long Sudarshan Kriya Yoga (LSKY). LSKY is a sequential combination of pranayama in ujjayi breath, bhastrika, and cyclic rhythmic breathing followed by yog-nidra.

METHODS

Regular LSKY practitioners from the Art of Living community with more than two years of experience participated in the study (n = 22; age 40.09 ± 12.68). The Electrocardiogram (ECG), respiration, oxygen saturation, and concentrations of oxygen and carbon-di-oxide from exhaled air were recorded before and during LSKY. The time domain parameters of heart rate variability (HRV) were calculated from ECG. All parameters were compared and correlated at each stage of LSKY.

RESULTS

Highly significant reciprocal correlation was found between HRV parameters and respiration rate during LSKY. Both O2 consumption and CO2 production increased significantly during three stages of pranayama and decreased towards the end of cyclic breathing. We also saw increased SPO2 simultaneously.

CONCLUSION

The autonomic parameters exhibited reciprocal response to respiratory rate and correlated well to the ventilatory parameters. Further during LSKY we observed enhanced synchronization. In conclusion the LSKY has a potential to influence cardiorespiratory parameters for improving the performance of both systems. LSKY - enhances oscillations in HRV that resets the autonomic system, indicative of better cardiac health and prepares body for better metabolic response. Such changes are capable of inducing resilience along with physiological, psychological relaxation and emotional well-being.

Role of Meditation in Ameliorating Examination Stress Induced Changes in Cardiovascular and Autonomic Functions

Background

Examination stress is a very well-known model of psychological stress in students. It induces changes in systolic (SBP) and diastolic blood pressure (DBP), along with changes in heart rate variability (HRV) and baroreflex sensitivity (BRS), due to autonomic perturbations.

Purpose

To find out if Raj Yoga meditation (RYM) practice affects autonomic and cardiovascular function in healthy young subjects during periods of examination stress. Our primary objective was to evaluate the effect of one month of supervised RYM practice on ameliorating examination-induced changes in cardiovascular and autonomic function. The secondary objective was to measure the stress levels of medical students before and after RYM.

Methods

Pre-training measurements of SBP, DBP, HRV, and BRS were done, and the Medical Student Stressor Questionnaire (MSSQ) was administered to 80 participants one month before examinations. They were then trained in RYM. Post-training assessment of the same parameters was done after examinations and also after two months.

Results

In our study, RYM training decreased DBP (p = 0.01) but not SBP. BRS showed a trend towards an increase after RYM practice, but it was not statistically significant (p = 0.44). The standard deviation of the NN interval (SDNN) (p = 0.03), low-frequency (LF) nu (0.003), and high-frequency (HF) nu (0.04) showed a statistically significant change. Average RR, median RR, average rate, square root of the mean squared differences of successive NN intervals (RMSSD), pRR, total power, LF (µs2), and LF/HF ratio were not statistically significantly different between the three groups. There was a statistically significant decline in MSSQ scores for MSSQ I (p = 0.04), MSSQ II (p = 0.04), and MSSQ IV (p = 0.03).

Conclusion

Short-term practice of supervised RYM during stressful periods is protective for the cardiovascular and autonomic systems and decreases stress in medical students.

Progressive resistance training ameliorates deteriorating cardiac autonomic dysfunction, subclinical inflammation and endothelial dysfunction in type 2 diabetes mellitus: A randomized control trial

BACKGROUND AND AIMS

To investigate the effect of resistance training (RT) on outcomes of cardiac autonomic control, biomarkers of subclinical inflammation, endothelial dysfunction, and angiotensin II in T2DM patients with CAN.

METHODS

Fifty six T2DM patients with CAN were recruited in the present study.After baseline assessment of all outcome variables, patients were randomly allocated into two groups - RT (n = 28) and Control (n = 28). The experimental group underwent 12 weeks of RT and the control group received usual care. RT was performed at an intensity of 65%-75% of 1 RM, 3 times/week for 12 weeks. RT program included 10 exercises of major muscle groups in the body. Cardiac autonomic control parameters, subclinical inflammation and endothelial dysfunction biomarkers, and serum angiotensin II concentration were assessed at baseline and after 12 weeks.

RESULTS

Parameters of cardiac autonomic control showed significant improvement after RT (p < 0.05). Interleukin-6, interleukin-18 were significantly reduced while endothelial nitric oxide synthase was significantly increased post-RT (p < 0.05).

CONCLUSIONS

Findings of the present study suggest that RT has the potential to enhance deteriorating cardiac autonomic function in T2DM patients with CAN. RT also seems to have an anti-inflammatory role and it may also play some role in vascular remodeling in these patients.

TRIAL REGISTRATION

CTRI/2018/04/013321, Registered prospectively on 13th April 2018, Clinical Trial Registry, India.

Vasoconstriction during non-hypotensive hypovolemia is not associated with activation of baroreflex: A causality-based approach

Non-hypotensive hypovolemia simulated with oscillatory lower body negative pressure in the range of -10 to -20 mmHg is associated with vasoconstriction {increase in total peripheral vascular resistance (TPVR)}. Due to the mechanical stiffening of vessels, there is a disjuncture of mechano-neural coupling at the level of arterial baroreceptors which has not been investigated. The study was designed to quantify both the cardiac and vascular arms of the baroreflex using an approach based on Wiener-Granger causality (WGC) - partial directed coherence (PDC). Thirty-three healthy human volunteers were recruited and continuous heart rate and blood pressure {systolic (SBP), diastolic (DBP), and mean (MBP)} were recorded. The measurements were taken in resting state, at -10 mmHg (level 1) and -15 mmHg (level 2). Spectral causality - PDC was estimated from the MVAR model in the low-frequency band using the GMAC MatLab toolbox. PDC from SBP and MBP to RR interval and TPVR was calculated. The PDC from MBP to RR interval showed no significant change at -10 mmHg and -15 mmHg. No significant change in PDC from MBP to TPVR at -10 mmHg and -15 mmHg was observed. Similar results were obtained for PDC estimation using SBP as input. However, a significant increase in TPVR from baseline at both levels of oscillatory LBNP (p-value <0.001). No statistically significant change in PDC from blood pressure to RR interval and blood pressure to TPVR implies that vasoconstriction is not associated with activation of the arterial baroreflex in ≤-15 mmHg LBNP. Thereby, indicating the role of cardiopulmonary reflexes during the low level of LBNP simulated non-hypotensive hypovolemia.

A narrative review on yoga: a potential intervention for augmenting immunomodulation and mental health in COVID-19

Background

The ongoing novel coronavirus disease 2019 (COVID-19) pandemic has a significant mortality rate of 3–5%. The principal causes of multiorgan failure and death are cytokine release syndrome and immune dysfunction. Stress, anxiety, and depression has been aggravated by the pandemic and its resultant restrictions in day-to-day life which may contribute to immune dysregulation. Thus, immunity strengthening and the prevention of cytokine release syndrome are important for preventing and minimizing mortality in COVID-19 patients. However, despite a few specific remedies that now exist for the SARS-CoV-2virus, the principal modes of prevention include vaccination, masking, and holistic healing methods, such as yoga. Currently, extensive research is being conducted to better understand the neuroendocrinoimmunological mechanisms by which yoga alleviates stress and inflammation. This review article explores the anti-inflammatory and immune-modulating potentials of yoga, along with its role in reducing risk for immune dysfunction and impaired mental health.

Methods

We conducted this narrative review from published literature in MEDLINE, EMBASE, COCHRANE databases. Screening was performed for titles and abstracts by two independent review authors; potentially eligible citations were retrieved for full-text review. References of included articles and articles of major non-indexed peer reviewed journals were searched for relevance by two independent review authors. A third review author checked the excluded records. All disagreements were resolved through discussion amongst review authors or through adjudication by a fourth review author. Abstracts, editorials, conference proceedings and clinical trial registrations were excluded.

Observations

Yoga is a nonpharmacological, cost-effective, and safe intervention associated with several health benefits. Originating in ancient India, this vast discipline consists of postures (asanas), breathing techniques (pranayama), meditation (dhyana/dharana), and relaxation. Studies have demonstrated yoga’s ability to bolster innate immunity and to inhibit cytokine release syndrome. As an intervention, yoga has been shown to improve mental health, as it alleviates anxiety, depression, and stress and enhances mindfulness, self-control, and self-regulation. Yoga has been correlated with numerous cardioprotective effects, which also may play a role in COVID-19 by preventing lung and cardiac injury.

Conclusion and relevance

This review paves the path for further research on yoga as a potential intervention for enhancing innate immunity and mental health and thus its role in prevention and adjunctive treatment in COVID-19.

Electrophysiological Evidence of Local Sleep During Yoga Nidra Practice

Background and Objectives

Yoga nidra is a technique sages use to self-induce sleep. Classically, sleep is characterized by three cardinal electrophysiological features, namely, electroencephalography (EEG), electromyography (EMG), and electrooculography (EOG). As the literature on electrophysiological characterization of Yoga nidra is lacking, it is not known whether it is a sleep or awake state. The objective of the study was to electrophysiologically characterize yoga nidra practice.

Materials and Methods

Thirty subjects underwent five initial supervised yoga nidra sessions and then continued practice on their own. The subjects completed their sleep diaries for 2 weeks before and during the intervention. The electrophysiological characterization was done after 2 weeks of yoga nidra practice using 19 EEG channels polysomnography for pre-yoga nidra, yoga nidra practice and post-yoga nidra. Polysomnographic data were scored for sleep-wake stages as per standard criteria. Power spectral density (PSD) was calculated from various frequency bands in different time bins. EEG data were grouped by areas, namely, central, frontal, prefrontal, parietal, temporal, and occipital in time bins. Sleep diary parameters were also compared for pre-post-yoga nidra training.

Results

After 2 weeks of yoga nidra practice, awake was scored throughout the session (n = 26). PSD results (mean difference in dB between different time bins; P value) showed significant changes. When compared to pre-yoga nidra, there was an increase in delta power in the central area (1.953; P = 0.033) and a decrease in the prefrontal area (2.713; P = 0.041) during yoga nidra. Sleep diary showed improvement in sleep duration (P = 0.0001), efficiency (P = 0.0005), quality (P = 0.0005), and total wake duration (P = 0.00005) after 2 weeks of practice.

Interpretations and Conclusions

Yoga nidra practice in novices is electrophysiologically an awake state with signs of slow waves locally, often referred to as local sleep.

Clinical Trial

Clinical Trial Registry of India, http://www.ctri.nic.in/Clinicaltrials/pmaindet2.php? trialid = 6253, 2013/05/003682.

Temporal Analysis of Sequential Changes in Heart Rate Variability During Non-hypotensive Hypovolemia

INTRODUCTION

Haemorrhage is associated with changes in the cardiac autonomic drive which begins during early stages of mild haemorrhage. The knowledge of chronology of the autonomic changes at smaller timescale during the period of haemorrhage can help identify the primary autonomic parameter which signals the institution of cardiovascular reflex mechanisms.

AIM

To evaluate the heart rate variability in 2-min sequential segments with one minute overlap during and after the period of mild haemorrhage (450 ml) using blood donation as a model of acute blood loss.

METHODS

47 male blood donors who had volunteered for blood donation were recruited for the study. Continuous lead II ECG was recorded before the start of the blood donation (5 min), during the period of the blood donation (~ 5-7 min) and after blood donation (5 min). The parasympathetic and sympathetic drive to heart was estimated by measures of heart rate variability in time and frequency domain.

RESULTS

A significant decrease in the parameters assessing parasympathetic drive i.e., normalised High frequency (HFn) and NN50 (Number of pairs of adjacent NN intervals differing by more than 50 ms) and pNN50 (NN50 divided by the total number of all NN Intervals) was observed during blood donation at 3-5 min, as compared to baseline. An increase in parameters associated with sympathetic drive i.e., normalised low frequency (LFn) was observed only in the post donation period at 2-3 min. A significant rise in LF/HF ratio which is a marker of sympatho vagal balance was observed at 4-5 min during blood donation when compared to baseline.

CONCLUSION

The initial cardiac autonomic change during mild haemorrhage is withdrawal of parasympathetic drive, followed by an increase in sympathetic tone which occurs much later.

Assessment of myocardial sympathetic innervation with 18F-FDOPA-PET/CT in patients with autonomic dysfunction: feasibility study in IPD patients

BACKGROUND

Dysfunction and denervation of myocardial nor-adrenergic sympathetic neurons has been documented in IPD patients with dysautonomia. The aim of this study was to evaluate the feasibility of single tracer imaging of myocardial sympathetic and cerebral striatal involvement in these patients.

METHODS

Twenty-two controls (mean-age 59.09 ± 12.39 years, 15 men) with no clinical autonomic-dysfunction and normal striatal-uptake in 18F-FDOPA-PET/CT; and 28 patients (mean-age 58.18 ± 8.25 years, 18 men) with autonomic-dysfunction (in Autonomic Function Tests) and striatal dopaminergic-dysfunction were enrolled. Both cardiac-PET/CT (40 minutes post IV-injection of 185-259MBq 18F-FDOPA) and Brain-PET/CT (60 minutes post-IV) were acquired in same session. ROIs were drawn over the entire left ventricular myocardium, individual walls and mediastinum for quantification. Patients and controls were followed-up for 26.93 ± 5.43 months and 37.91 ± 8.63 months, respectively.

RESULTS

Striatal and myocardial-parameters were significantly lower in patients compared to controls; with Myocardium/mediastinal ratio (MwMR) yielding the area-under-the-curve of .941 (P < .001). MwMR correlated negatively with the drop in systolic blood pressure (SBP) during AFTs {Pearson-coefficient (-).565, P = .002}. Mean MwMR in patients with abnormal-AFTs was significantly lower than patients with borderline-AFTs (1.39 ± .12 vs 1.55 ± .10; P = .002). 9/20 patients with abnormal-AFTs showed functional worsening during follow-up, compared to 2/8 with borderline-AFTs.

CONCLUSION

Single tracer, single session imaging of striatal and cardiac sympathetic dysfunction in patients with advanced IPD is feasible with use of 18F-FDOPA. Significantly reduced 18F-FDOPA uptake is seen in the myocardium of the IPD patients with sympathetic dysfunction.

Effect of countermeasure bodygear on cardiac-vascular-respiratory coupling during 6-degree head-down tilt: An earth-based microgravity study

Prolonged exposure to microgravity causes physiological deconditioning in humans. Herein, a novel designed countermeasure gravitational load modulation bodygear has been developed to deal with the ill effects of the microgravity environment. The bodygear is designed to provide the wearer an axial loading from the shoulder to the feet that simulate Earth's gravity. The present study aims to evaluate the effect of bodygear on cardiac, vascular and respiratory systems during head-down tilt (HDT) microgravity analogue. In this, 30 healthy male subjects have volunteered and their average age, height and weight were 24.56 ± 3.87 yr, 168.4 ± 9.17 cm and 65.9 ± 10.51 kg respectively. The physiological signals such as electrocardiogram (ECG), blood pressure (BP) and respiration were recorded non-invasively using Biopac MP100. The signals were sampled at 1,000 Hz and processed using MATLAB 2018b. The signals were analysed in linear well as non-linear domains. The ECG and BP were used to derive R-R interval (RRI) and systolic blood pressure (SBP). The respiration time series (RSP) was derived by extracting R-peaks from the ECG signal and using these peaks to find the respiration amplitude. The non-linear domain analysis was used for the detection and quantification of information flow among the recorded signals. Repeated measure analysis of variance with Bonferroni post-hoc paired t-test was used for statistical analysis with the p < 0.05. The experimental results show that the 6-degree HDT activates the parasympathetic system and decreased the RRI effect on SBP (p = 0.005). Interestingly with the bodygear usage, the sympathetic system activated, mean RRI decreased (p = 0.018) and blood pressure increased (p = 0.031) as compared to baseline. Further, it was also observed that the effect of RRI on SBP (p = 0.029) and SBP on RRI (p = 0.012) was increased with bodygear as compared to HDT without bodygear. The conditional entropy technique aided in analyzing the effect of bodygear on information flow variation in the cardiovascular system of the human body.

A systematic review and meta-analysis of effect of yoga and meditation on endothelial system

Background/Introduction

Endothelial dysfunction plays an important role in the pathophysiology of cardiovascular diseases and diabetes. Studies reported either an improvement in endothelial function by yoga and meditation or no significant effect. A systematic review and meta-analysis of effect of yoga on endothelial function is not available.

Purpose

The aim of this systematic review and meta-analysis is to determine the effectiveness of yoga and meditation on endothelial function in healthy subjects or patients of any age or gender.

Methods

Authors performed a systematic search for relevant research studies as per the PRISMA guidelines. The Pubmed, Scopus, Google Scholar and Cochrane controlled register of trials (CENTRAL) were screened from inception to November 2020. The search strategy was constructed around yoga based techniques, meditation and endothelial function. All the yoga-based interventional studies on endothelial function: controlled, uncontrolled, randomized, non-randomized and cross-over were included for this review. A narrative synthesis and descriptive analysis was done due to diverse methodology of all selected studies. We carried out a formal meta-analysis of controlled trials that assessed flow-mediated dilatation (FMD) which is a gold-standard measure of endothelial function.The quality of the studies was assessed using Cochrane risk of bias (RoB) tool.

Results

A total of 18 studies were included for review involving 1024 participants. Of these, 10 were RCT, one randomized cross-over study, 4 non-randomized studies and three single-group (before-after) studies. The total duration of yoga intervention ranged from 10 days to 52 weeks. Among the 18 selected studies, yoga training showed a significant favorable change in the measures of endothelial function in 12 studies (involving either healthy individuals or patients with coronary heart disease, myocardial infarction, metabolic syndrome, hypertension, migraine and dysmenorrhea) while 6 studies did not find any significant effect. Among the 15 controlled trials, 7 assessed FMD while the remaining evaluated different biomarkers of endothelial function such as circulating endothelial microparticles, asymmetric dimethyl arginine, nitric oxide or endothelin-1. Hence the results of 7 controlled trials assessing FMD were included for meta-analysis (n=384 participants) which showed a significant increase in brachial FMD by yoga practice (Mean difference = −2.02%, 95% CI: −3.72, −0.32, p=0.02). The heterogeneity between the studies was 76% (τ2=3.31, χ2=25.28) (Fig. 1).

Conclusions

Yoga and meditation can significantly improve endothelial function in healthy individuals and patients with cardiovascular disease or risk factors. Yoga and meditation can be applied clinically as a lifestyle modality for endothelial protection and cardiovascular prevention and rehabilitation.

Funding Acknowledgement

Type of funding sources: None.

Yoga Practitioners Exhibit Higher Parasympathetic Activity and Baroreflex Sensitivity and Better Adaptability to 40 mm Hg Lower-Body Negative Pressure

Yoga has been shown to improve autonomic conditioning in humans, as evidenced by the enhancement of parasym-pathetic activity and baroreflex sensitivity. Therefore, we hypothesized that the experience of yoga may result in adaptation to acute hemodynamic changes. To decipher the long-term effects of yoga on cardiovascular variability, yoga practitioners were compared to yoga-naïve subjects during exposure to -40 mm Hg lower-body negative pressure (LBNP). A comparative study was conducted on 40 yoganaïve subjects and 40 yoga practitioners with an average age of 31.08 ± 7.31 years and 29.93 ± 7.57 years, respectively. Heart rate variability, blood pressure variability, baroreflex sensitivity, and correlation between systolic blood pressure and RR interval were evaluated at rest and during LBNP. In yoga practitioners, the heart rate was lower in supine rest (p = 0.011) and during LBNP (p = 0.043); the pNN50 measure of heart rate variability was higher in supine rest (p = 0.011) and during LBNP (p = 0.034). The yoga practitioners' standard deviation of successive beat-to-beat blood pressure intervals of systolic blood pressure variability was lower in supine rest (p = 0.034) and during LBNP (p = 0.007), with higher sequence baroreflex sensitivity (p = 0.019) and ~ high-frequency baroreflex sensitivity. Mean systolic blood pressure and RR interval were inversely correlated in the yoga group (r = -0.317, p = 0.049). The yoga practitioners exhibited higher parasympathetic activity and baroreflex sensitivity with lower systolic blood pressure variability, indicating better adaptability to LBNP compared to the yoga-naïve group. Our findings indicate that the yoga module was helpful in conditions of hypovolemia in healthy subjects; it is proposed to be beneficial in clinical conditions associated with sympathetic dominance, impaired barore-flex sensitivity, and orthostatic intolerance.

A Cross-Sectional Study on Central Sensitization and Autonomic Changes in Fibromyalgia

Fibromyalgia is a multi-symptomatic disorder characterized by generalized pain. The pathophysiology of fibromyalgia is supposedly an interplay between central nervous system hyper-responsiveness, autonomic dysfunction, and peripheral pain. In this cross-sectional study, the objective was to assess central sensitization and autonomic activity in patients with fibromyalgia compared with control. Fifty adults diagnosed with fibromyalgia by the modified American College of Rheumatology 2010 criteria and an equal number of age- and sex-matched controls participated in the study in an urban tertiary care hospital. Central sensitization was assessed by history and by evidence of increased prefrontal cortical activity as measured by cortical oxygenation using functional near-infrared spectroscopy. Autonomic activity was assessed by heart rate variability, electrodermal activity, and deep breathing test in three physiological states: rest, sympathetic stress (cold pressor test), and deep breathing. Mann–Whitney U-test, paired t-test, Wilcoxon test, and Friedman test with Bonferroni a priori were used to analyze the data. Cortical activity was significantly higher in the fibromyalgia group than control. There was no significant difference in autonomic activity between the fibromyalgia and control groups. In the fibromyalgia group, variable degrees of sympathetic hyperactivity and normal parasympathetic activity were observed. Central sensitization may be playing a primary role in the pathophysiology of generalized pain in fibromyalgia.

The Low-Flow-Mediated Arterial Constriction in the Upper Limbs of Healthy Human Subjects are Artery Specific and Handedness Independent

Low-flow-mediated constriction (LFMC) has been used to assess resting endothelial function in peripheral conduit arteries. The literature describes discrepancies in the behaviour of radial versus brachial artery in response to low-flow state, the reasons for which were not addressed in a systematic and scientific way. Moreover, the influence of handedness on observed LFMC responses has not been investigated. The present study aimed at systematic measurement and comparison of the LFMC responses in radial and brachial arteries of both dominant and non-dominant arms of healthy human volunteers. We also investigated the physiological factors associated with differential LFMC response of radial versus brachial artery in the same group of subjects. Longitudinal B mode ultrasonographic cine loops of radial and brachial arteries were acquired at baseline and after producing distal circulatory arrest. Cine loops were screen grabbed and analyzed later using automated edge detection algorithms to measure end-diastolic diameters. Distal circulatory arrest was produced over the proximal forearm (for the brachial artery) and over the wrist (for the radial artery) at 250 mm Hg for 5 min after baseline measurements. Results suggested that arterial location (p = 0.0001) and baseline diameter (p < 0.0021) emerged as independent predictors of LFMC response. Differences in the LFMC responses are handedness independent and could be attributed to the arterial location along with the differences in their baseline diameters.

An optimal interval type-2 fuzzy logic control based closed-loop drug administration to regulate the mean arterial blood pressure

BACKGROUND AND OBJECTIVE

The main aim of this work is to present an optimal and robust controller design in order to improve the drug infusion to the automatic control of mean arterial blood pressure in conditions like critically-ill or post-operative or anaesthesia administration. The physiological systems also have uncertainty issues such as parameter variations with time or external disturbances and noise. Therefore, a controlled drug administration is necessary to regulate the mean arterial blood pressure of a person during surgery/observation. Over the years, the proportional-integral-derivative (PID) controller is the most commonly used controller in industries due to its easy structure and simplicity. However, this controller does not meet the desired performance with the complex and uncertain plants. Therefore, a robust controller is required to regulate the physiological variables that are uncertain in nature and can affect the human life.

METHODS

In this work, a hybrid control scheme consisting of an interval type-2-fuzzy logic controller which acts as pre-compensator to the traditional PID controller is presented, to regulate the mean arterial blood pressure of a patient by administering the drug sodium nitroprusside in a controlled manner. An effective and well-established nature-inspired optimization technique namely cuckoo search algorithm is employed for obtaining the optimal parameters for the presented scheme.

RESULTS

Simulation results are presented to show the effectiveness and robustness of proposed interval type-2-fuzzy logic controller based PID controller scheme, for maintaining the mean arterial pressure to 100 mmHg within considerable limit through SNP infusion. The results are further compared with other two controllers namely type-1 fuzzy logic based PID and traditional PID controllers for the parameter variations and external noise.

CONCLUSION

In this study, the proposed interval type-2-fuzzy logic controller pre-compensator based PID controller provides an effective control than traditional type-1 fuzzy logic based control scheme and PID controller in terms of overshoot, settling-time and error which are the prime performance objectives of the closed-loop controlled drug delivery of human blood pressure. The presented study provides a firm base for initial design considerations for development of a low-cost closed-loop drug delivery system for blood pressure regulation.

IDENTIFYING DEEP BREATH EFFECT ON CARDIOVASCULAR SIGNALS USING CONDITIONAL ENTROPY: AN INFORMATION DOMAIN APPROACH

This quantitative study identifies the coupling changes occurring among cardiac (RR), vascular (SBP) and respiratory (RESP) signals during deep breathing. The deep breathing measures the dysfunction of the parasympathetic autonomic nervous system. The traditional methods based on cross-correlation and coherence analysis lack to measure nonlinear structures and unpredictability of physiological subsystems. Therefore, information domain coupling method based on conditional entropy is proposed to detect the coupling changes. Thirty healthy volunteers were examined for 5[Formula: see text]min at normal breathing and 5[Formula: see text]min during deep breathing (6[Formula: see text]cycles/min). The reduction in respiration rate detects a significant increase in information flow from RESP to RR, RESP to SBP and SBP to RR. The increased interaction from RESP to RR and RESP to SBP at reduced respiration rate indicates the enhancement of respiratory sinus arrhythmia that results in the activation of the parasympathetic nervous system. Also, the balanced cardiovascular interaction observed on normal breathing from RR to SBP disappears, but interaction occurring in baroreflex direction (SBP to RR) increases that helps in the reduction of blood pressure during deep breathing. This detected direction of information flow helps in identifying the coupling changes occurring during parasympathetic nerve activity.

A Novel Modular Tonometry-Based Device to Measure Pulse Pressure Waveforms in Radial Artery

The paper presents the development of a new device for measuring continuous pulse pressure waveforms (PPW) from the radial artery via applanation tonometry. The development focuses on improved accuracy, open and affordable design using off-the-shelf components, and greater user control in setting operational and calibration parameters to address user variability. The device design parameters are optimized through a tissue device interaction study based on a computational model. The design incorporates modular components and includes a sensor module for arterial flattening and pressure pick-up, a differential screw mechanism and a related algorithm for controlled stepwise motion and data collection during flattening, and a brace for wrist-flexion adjustment. Maximum pulse amplitude (PA) was used as an indicator of the optimum level of arterial flattening for recording the PPW. The PPW was observed to distort due to changes in parameters like gel-head placement, hold-down pressure (HDP), and wrist extension. The pressure waveforms collected using the device were validated using limited data against established products and showed good correlation within ±1.96 standard deviation of the mean difference in a Bland–Altman plot. This paper thus details the development of a simple and validated mechanical design to measure PPW using arterial tonometry.

Abstract TP403: Effect of Hypercapnia on Dynamic Cerebral Autoregulation During Transient Hypotension

Background and Purpose: Hypercapnia leads to increased cerebral blood flow and impaired autoregulation by changing the cerebrovascular resistance (CVR). We studied the effect of hypercapnia on critical closing pressure (CCP) and resistance area product (RAP) which effectively reflects the role of vascular tone and resistance respectively in altering cerebrovascular resistance and maintaining cerebral autoregulation during transient hypotension.

Methods: –26 healthy subjects had continuous cerebral blood flow velocity and arterial blood pressure recording. Transient hypotension was induced by sudden release of thigh cuff after suprasystolic inflation for 3 minutes. 3 trials of thigh cuff maneuver were performed with normal breathing, 3% CO 2 breathing and 5% CO 2 breathing. CO 2 inhalation was given for last 45 seconds of thigh cuff maneuver and continued for 90 seconds after release. Autoregulatory Index (ARI) was calculated for each trial with Tieck’s model. CCP and RAP were computed for 10 seconds’ window each at 1 minute after inflation (Baseline), immediately before release (Prerelease) and immediately after release (Release) of inflated thigh cuff.

Results: –ARI values decreased significantly (p < 0.0001) from 5.46 ± 1.47 to 2.0 ± 1.35 and 1.63 ± 1.09 during 3% CO 2 and 5% CO 2 trial respectively. No significant changes were observed in CCP value during thigh cuff release with all three trials. RAP significantly dropped from prerelease value after thigh cuff release in all 3 trials. Drop in RAP attenuated during hypercapnia trial and had significant (p < 0.0001) difference between RAP Prerelease – Release ( d RAP) for Normal breathing (0.20 ± 0.12) and 3% and 5 % CO 2 trials (0.089 ± 0.090, 0.081 ± 0.093). d RAP was significantly correlated (Spearmen r = 0.42, p = 0.0004) with the ARI values where higher d RAP had better autoregulation.

Conclusion: – Cerebral autoregulation during transient hypotension acts by changing vascular resistance i.e. RAP without any effect on vascular tone i.e. CCP and had been suggested to reflect myogenic component of autoregulation to blood pressure changes. We concluded that hypercapnia leads to impairment of myogenic component of autoregulation during transient arterial blood pressure changes as suggested by attenuated d RAP.

Narrowing of the Anterior Chamber Angle during Valsalva Maneuver: A Possible Mechanism for Angle Closure

Purpose

To evaluate changes at the anterior chamber angle during Valsalva maneuver in eyes suspected to have a primary adult glaucoma.

Methods

Seventy-six consecutive patients underwent recording of applanation tonometry, measurement of the anterior chamber angle recess, angle opening distance, angle recess area, scleral spur-iris root distance, iris thickness, iridociliary angle, ciliary body thickness, anterior chamber depth, and pupil size on ultrasound biomicroscopy before and during the Valsalva maneuver. The Valsalva maneuver was standardized to a pressure of 40 mmHg for 15 seconds, using a manometer.

Results

The mean baseline intraocular pressure changed from 19.5±4.1 mmHg to 29.5±4.8 mmHg during Valsalva (p<0.0001). The anterior chamber angle recess narrowed from 17.9±9.5 to 7.8±9.2 degrees (p=0.0001). The angle recess area diminished from 0.15±0.14 mm2 to 0.14±0.12 mm2 (p=0.03) and the scleral spur to iris distance decreased from 0.19±0.2 mm to 0.16±0.18 mm (p=0.0001). The iridociliary angle narrowed from 72.6±33.5 degrees to 62.5±32.8 degrees (p=0.04). There was a significant increase in the thickness of the ciliary body, from 0.99±0.19 mm to 1.12±0.16 mm (p=0.001) and in iris thickness from 0.47±0.07 mm to 0.55±0.09 mm (p=0.0001). There was no significant change in the angle opening distance, anterior chamber depth, or pupillary diameter. A significant narrowing of the angle to less than 5 degrees was seen in 37 eyes, with iridocorneal apposition present in 28 eyes. After multivariate regression analysis it was found that the baseline ciliary body thickness and angle recess were significant predictors of narrowing of the angle (R2=96.1%).

Conclusions

Significant elevation of the intraocular pressure, narrowing of the anterior chamber angle recess, thickening of the ciliary body, and increase in the iris thickness is seen during the Valsalva maneuver. The Valsalva maneuver may lead to angle closure in eyes anatomically predisposed to primary angle closure glaucoma.

Reduced Baroreflex Sensitivity, Decreased Heart Rate Variability with Increased Arterial Stiffness in Predialysis

High cardiovascular morbidity and mortality is observed in predialytic chronic kidney disease (CKD) patients. The underlying mechanism of cardiovascular dysfunction often remains unclear. The present study was designed to perform multiparametric assessment of baroreflex sensitivity (BRS), arterial stiffness indices, and cardiovascular variabilities (heart rate variability [HRV] and blood pressure variability [BPV]) together in predialytic CKD patients; compare it with normal healthy controls; and determine their relationships in predialytic nondiabetic CKD patients. Thirty CKD Stage 4 and 5 predialytic non-diabetic patients and 30 healthy controls were enrolled in the study. BRS was determined by spontaneous sequence method. Short-term HRV and BPV were assessed using 5 min beat-to-beat data of RR intervals and blood pressure by time domain and frequency domain analysis. Arterial stiffness indices - carotid-femoral pulse wave velocity (PWV) and augmentation index - were measured using SphygmoCor Vx device (AtCor Medical, Australia). Predialytic CKD patients had significantly low BRS, high PWV, and low HRV as compared to healthy controls. Independent predictors of reduced systolic BRS in predialytic CKD patient group on multiple regression analysis emerged to be increase in calcium-phosphate product, increase in BPV, and decrease in HRV. Predialytic nondiabetic CKD Stage 4 and 5 patients have poor hemodynamic profile (higher PWV, lower HRV, and reduced BRS) than healthy controls. Reduced HRV and altered calcium-phosphate homeostasis emerged to be significant independent predictors of reduced BRS.

Assessment of Cardiac Autonomic Tone Following Long Sudarshan Kriya Yoga in Art of Living Practitioners

OBJECTIVE

The breathing processes are known to modulate cardiac autonomic tone and improve psychological status. We investigated cardiac autonomic tone following long Sudarshan Kriya Yoga (SKY) using heart rate variability (HRV) and skin conductance level (SCL).

METHODS

Thirty healthy volunteers (age 28.3 ± 8.4 years; 23 M: 7 F) participated in the study. Electrocardiogram (ECG) and SCL were recorded for 5 min each, before and after long SKY. Long SKY is a combination of pranayama and cyclic rhythmic breathing and is performed by following the guided audio instructions. HRV analysis was used for the assessment of cardiac autonomic tone. Time and frequency domain parameters of HRV were calculated by using RR interval of ECG. SCL was acquired using Galvanic skin response (GSR) amplifier of PowerLab in microSeimens (μS).

RESULTS

Time domain parameters of HRV, including mean RR interval (p = 0.000), respiratory sinus arrhythmia (RSA) (p = 0.037), standard deviation of all NN intervals (SDNN) (p = 0.013), NN50 count divided by the total number of all NN intervals (pNN50) (p = 0.004), and square root of the mean of the sum of the squares of differences between adjacent NN intervals (RMSSD) (p = 0.002) increased, and mean heart rate decreased (p = 0.000) following long SKY. In frequency domain analysis, power of low-frequency (LF) component (p = 0.010) and LF/HF ratio (p = 0.008) decreased significantly, whereas power of high frequency (HF) significantly increased (p = 0.010). SCL decreased following long SKY, although it did not attain statistical significance.

CONCLUSIONS

The results suggest that long SKY induces significant oscillations in cardiac autonomic tone. Parasympathetic activity increases and sympathetic activity decreases and sympathovagal balance improves following long SKY. Decrease in sympathetic activity is also demonstrated by decrease in conductance although it did not reach statistical significance. From this study it can be concluded that long SKY has a beneficial effect on cardiac autonomic tone, and psychophysiological relaxation. It may serve as a tool to improve HRV, which is the marker of cardiovascular health.

Decreased Spontaneous Baroreflex Sensitivity as an Early Marker for Progression of Haemorrhage

INTRODUCTION

Blood donation provides an ideal setup for assessment of cardiovascular responses to mild hypovolemia for understanding the underlying mechanisms.

AIM

To evaluate cardiovascular responses in time and magnitude by estimating the spontaneous baroreflex sensitivity (BRS) during and after donation of 450 ml of blood.

METHODS

Continuous beat-to-beat blood pressure and lead II ECG was recorded before, during and after blood donation in 54 healthy volunteers (age 34.7 ± 5.08 years; weight 77.9 ± 8.20 kg), followed by offline analyses of baroreflex sensitivity.

RESULTS

The systolic, diastolic or mean blood pressures did not change during or after the blood donation. Decrease in pulse pressure and increase in heart rate was observed post donation. The spontaneous BRS decreased during [8.68 (6.038-12.69) ms/mmHg] and after blood donation [9.401 (6.396-11.59) ms/mmHg] as compared to the baseline [12.83 (6.884-18.18) ms/mmHg] with a significant decrease in α-HF on spectral analysis.

CONCLUSION

Mild blood loss (450 ml) results in non-hypotensive haemorrhage with a decrease in spontaneous BRS before the rise of heart rate during blood donation.

Cardiovascular Autonomic Dysfunction in Children and Adolescents With Rett Syndrome

BACKGROUND

Autonomic dysfunction is common in children with Rett syndrome. They usually manifest with agitation, persistent screaming, constipation, gastroesophageal reflux, aerophagia, hyperventilation, and breath-holding episodes. Cardiovascular autonomic dysfunction may result in fatal a arrhythmia. Many of these events are mistaken for seizures and treated with antiepileptics.

METHODS

The present study was conducted in a tertiary care teaching hospital in north India for more than a six month period. MeCP2 mutation positive, 24 cases with Rett syndrome and 24 age-matched healthy girls were evaluated for cardiovascular autonomic dysfunction (heart rate variability, head-up tilt test, and cold pressor test).

RESULTS

The mean age was 9.06 years (±3.4) and 9.75 years (±3.13) for patients and control subjects, respectively. The heart rate variability contributed independently by parasympathetic and sympathetic nervous system was significantly reduced in cases compared with control subjects (P = 0.033 and P = 0.001, respectively). There was significant sympathovagal imbalance with sympathetic overactivity in cases compared with control subjects (P = 0.001). The mean longest QT_c interval was significantly prolonged in cases compared with control subjects (P = 0.001). Cold pressor test and head-up tilt test could be done in 16 Rett syndrome patients (because of poor cooperation) and in all 24 control subjects. The change in blood pressure during cold pressor test and head-up tilt test was not significantly different in cases and control subjects.

CONCLUSIONS

Children with Rett syndrome exhibited significant cardiovascular autonomic dysfunction in the form of sympathetic overactivity, parasympathetic underactivity, and sympathovagal imbalance. These findings have potentially important therapeutic- and outcome-related implications.

Modulation of cardiac autonomic tone in non-hypotensive hypovolemia during blood donation

Non-hypotensive hypovolemia, observed during mild haemorrhage or blood donation leads to reflex readjustment of the cardiac autonomic tone. In the present study, the cardiac autonomic tone was quantified using heart rate and blood pressure variability during and after non-hypotensive hypovolemia of blood donation. 86 voluntary healthy male blood donors were recruited for the study (age 35 ± 9 years; weight 78 ± 12 kg; height 174 ± 6 cms). Continuous lead II ECG and beat-to-beat blood pressure was recorded before, during and after blood donation followed by offline time and frequency domain analysis of HRV and BPV. The overall heart rate variability (SDNN and total power) did not change during or after blood donation. However, there was a decrease in indices that represent the parasympathetic component (pNN50 %, SDSD and HF) while an increase was observed in sympathetic component (LF) along with an increase in sympathovagal balance (LF:HF ratio) during blood donation. These changes were sustained for the period immediately following blood donation. No fall of blood pressure was observed during the period of study. The blood pressure variability showed an increase in the SDNN, CoV and RMSSD time domain measures in the post donation period. These results suggest that mild hypovolemia produced by blood donation is non-hypotensive but is associated with significant changes in the autonomic tone. The increased blood pressure variability and heart rate changes that are seen only in the later part of donation period could be because of the progressive hypovolemia associated parasympathetic withdrawal and sympathetic activation that manifest during the course of blood donation.

Impaired systemic vascular reactivity & raised high-sensitivity C reactive protein levels in chronic obstructive pulmonary disease

BACKGROUND & OBJECTIVES

Chronic obstructive pulmonary disease (COPD) is characterized by slowly progressive airflow limitaion, chronic lung inflammation and associated systemic manifestations. The objective of this preliminary study was to investigate the levels of high sensitivity C reactive protein (hs CRP) and tumour necrosis factor-α (TNF-α) as markers of systemic inflammation and assessment of systemic vascular reactivity that may play an important role in development of cardiovascular disease in COPD patients.

METHODS

Systemic vascular reactivity was assessed non-invasively by measuring peripheral pulse waveform changes during reactive hyperemia (RH) in 16 COPD patients and 14 controls by photoplethysmography technique (PPG). Parameters measured were pulse wave amplitude (PWA), slope and pulse transit time (PTT). Tumour necrosis factor-α (TNF-α) and hs CRP were measured as markers of inflammation.

RESULTS

PWA during the 1 st , 2 nd and 3 rd minutes post release of occlusion were significantly higher than the baseline means in controls, whereas in the patient group there was no significant change in the PWA during any of the observed time periods following release of occlusion, in comparison to the baseline means. Similar results were observed in slope values for patients and controls. Maximum percentage change in PWA during RH with reference to baseline was significantly lower in patients as compared to controls (26.78±20.19 vs 57.20±19.80%, p<0.001). Maximum percentage change in slope during RH with reference to baseline was significantly lower in patients as compared to controls (19.77±10.73 vs 39.25±13.49%, P<0.001). A vascular tone response as represented by PTT was also impaired in the 3 rd minute of RH as compared to baseline mean values in COPD patients only.

INTERPRETATION & CONCLUSIONS

Our findings showed raised hs CRP levels and impaired systemic vascular reactivity in COPD patients. Whether these may increase the risk of cardiovascular disease in COPD patients need to be confirmed in future studies with large sample size and appropriate study design.

Vascular Responses to Post Occlusive Reactive Hyperemia and Systemic Inflammation in Overlap Syndrome of Chronic Obstructive Pulmonary Disease and Obstructive Sleep Apnea

BACKGROUND

Post-occlusive reactive hyperemia (RH) is impaired in Chronic Obstructive Pulmonary Disease (COPD) and Obstructive Sleep Apnea (OSA). The aim of the present study was to examine systemic vascular response and endothelial function in patients of Overlap Syndrome (OS) of COPD and OSA and also to investigate whether OS has any additional effect on endothelial dysfunction when compared to dysfunction caused by COPD alone.

METHODS

31 COPD patients and 13 healthy controls participated in the study. Overnight Polysomnogra was done to classify the patients into COPD only group (Apnea-Hypopnea Index <5) (n=15) and OS group (AHI >5) (n=16). Peripheral pulse waveform changes during reactive hyperemia were assessed using digital Photoplethysmography (PPG) technique in which pulse wave amplitude (PWA), Maximum slope of upstroke and Pulse Transit Time (PTT) were measured. C - reactive protein was assessed as marker of inflammation by ELISA.

RESULTS

Maximum percentage changes in PWA during RH were significantly lower in the both COPD group [20.34(12.02-34.07)] (p<0.001) and Overlap Syndrome group [10.96(6.21-21.49)] (p<0.0001) as compared to Controls [49.79(46.03-65.32)], whereas amplitude responses were not significantly different in the COPD and OS group (p>0.05). Maximum percentage change in slope of upstroke showed similar responses in the three groups. CRP levels (mg/) were raised in COPD [11.60(1.75-15.00] (p<0.001) and OS group [12.52(5.28- 15.70))](p<0.0001) as compared to controls [0.59(0.58-0.91)]. Maximum percentage change in amplitude negatively correlated with serum CRP levels in COPD group (r=-0.557, p=0.03) and in OS group (r=-O.552, p= 0.02). FEV1% predicted positively correlated with maximum percentage change in amplitude in OS group(r=0.579, p=0.018). No correlation of AHI was found with any of the vascular function parameter in Overlap group.

CONCLUSION

The patients with Overlap Syndrome have systemic inflammation and impaired reactive hyperaemia response. However, no additive effect of OSA was observed on impaired RH in patients with co-existing COPD.

Completion report: Effect of Comprehensive Yogic Breathing program on type 2 diabetes: A randomized control trial

BACKGROUND

Yoga has been shown to be beneficial in diabetes in many studies, though randomized control trials are few. The aim of this randomized control trial was to see the effect of Sudarshan Kriya and related practices (comprehensive yogic breathing program) on quality of life, glycemic control, and cardiac autonomic functions in diabetes. Diabetes mellitus is a risk factor for sudden cardiac death. Cardiac autonomic neuropathy has been implicated in the causation of sudden cardiac death. Therefore, a maneuver to prevent progression of cardiac autonomic neuropathy holds significance.

MATERIALS AND METHODS

A total of 120 patients of diabetes on oral medication and diet and exercise advice were randomized into two groups: (1) Continued to receive standard treatment for diabetes. (2) Patients administered comprehensive yogic breathing program and monitored to regularly practice yoga in addition to standard treatment of diabetes. At 6 months, quality of life and postprandial plasma glucose significantly improved in the group practicing yoga compared to baseline, but there was no significant improvement in the fasting plasma glucose and glycated hemoglobin.

RESULTS

On per protocol analysis, sympathetic cardiac autonomic functions significantly improved from baseline in the group practicing comprehensive yogic breathing.

CONCLUSION

This randomized control trial points towards the beneficial effect of yogic breathing program in preventing progression of cardiac neuropathy. This has important implications as cardiac autonomic neuropathy has been considered as one of the factors for sudden cardiac deaths.

Extending professional education to health workers at grass root level: an experience from all India institute of medical sciences, new delhi

Background:

In India, the opportunities for professional education of the grass root level health workers are grossly inadequate. Capacity building of all categories of health workers is needed for enhancing health outcomes.

Objectives:

To plan and implement a professional development training program for all categories of allied health workers and to assess its outcomes in terms of knowledge and skills

Materials and Method:

We planned and organized a ‘one week’(15 h) training program for 10 categories of allied health workers (1260) working in our hospital. The program included nine generic skills/topics: the prestige of AIIMS, sterilization & infection control, universal precaution, biomedical waste management, public health, life style & healthy nutrition, fire safety, communication skills and office procedure besides subject specific skills. Trainers were drawn from 12 departments. Training methodology included interactive lectures, narratives, demonstrations, videos, PPT slides, and informal discussions with participants. The effectiveness of the program was judged on the basis of participants’ feedback, feedback from the supervisors, and our own observations post training.

Results:

Feedback from the participants and their supervisors after training was encouraging. The participants described training as a “life time experience”. The supervisors reported improvement in confidence, communication skills, and awareness of workers.

Conclusion:

The success of the program was due to the use of interactive methods, involvement of multidisciplinary team, and commitment from leadership. We recommend that professional education should be linked with career advancement. Academic institutions can play a key role in taking such initiatives.

Cardiac autonomic function in patients with diabetes improves with practice of comprehensive yogic breathing program

BACKGROUND

The aim of this study was to observe the effect comprehensive yogic breathing (Sudarshan Kriya Yoga [SKY] and Pranayam) had on cardiac autonomic functions in patients with diabetes.

MATERIALS AND METHODS

This is a prospective randomized controlled intervention trial. Cardiac autonomic functions were assessed in 64 diabetics. Patients were randomized into two groups, one group receiving standard therapy for diabetes and the other group receiving standard therapy for diabetes and comprehensive yogic breathing program. Standard therapy included dietary advice, brisk walking for 45 min daily, and administration of oral antidiabetic drugs. Comprehensive yogic breathing program was introduced to the participants through a course of 12 h spread over 3 days. It was an interactive session in which SKY, a rhythmic cyclical breathing, preceded by Pranayam is taught under the guidance of a certified teacher. Cardiac autonomic function tests were done before and after 6 months of intervention.

RESULTS

In the intervention group, after practicing the breathing techniques for 6 months, the improvement in sympathetic functions was statistically significant (P 0.04). The change in sympathetic functions in the standard therapy group was not significant (P 0.75). Parasympathetic functions did not show any significant change in either group. When both parasympathetic and sympathetic cardiac autonomic functions were considered, there was a trend toward improvement in patients following comprehensive yogic breathing program (P 0.06). In the standard therapy group, no change in cardiac autonomic functions was noted (P 0.99).

CONCLUSION

Cardiac autonomic functions improved in patients with diabetes on standard treatment who followed the comprehensive yogic breathing program compared to patients who were on standard therapy alone.

Consensus physical activity guidelines for Asian Indians

India is currently undergoing rapid economic, demographic, and lifestyle transformations. A key feature of the latter transformation has been inappropriate and inadequate diets and decreases in physical activity. Data from various parts of India have shown a steady increase in the prevalence of lifestyle-related diseases such as type 2 diabetes mellitus (T2DM), the metabolic syndrome, hypertension, coronary heart disease (CHD), etc., frequently in association with overweight or obesity. Comparative data show that Asian Indians are more sedentary than white Caucasians. In this review, the Consensus Group considered the available physical activity guidelines from international and Indian studies and formulated India-specific guidelines. A total of 60 min of physical activity is recommended every day for healthy Asian Indians in view of the high predisposition to develop T2DM and CHD. This should include at least 30 min of moderate-intensity aerobic activity, 15 min of work-related activity, and 15 min of muscle-strengthening exercises. For children, moderate-intensity physical activity for 60 min daily should be in the form of sport and physical activity. This consensus statement also includes physical activity guidelines for pregnant women, the elderly, and those suffering from obesity, T2DM, CHD, etc. Proper application of guidelines is likely to have a significant impact on the prevalence and management of obesity, the metabolic syndrome, T2DM, and CHD in Asian Indians.

Heart rate variability study of childhood anxiety disorders

Background:

The current study aims at assessment of heart rate variability among children and adolescents with childhood anxiety disorder, using the case-control design.

Materials and Methods:

The study was carried out at a tertiary care multispecialty hospital. It included 34 children and adolescents with diagnosis of childhood anxiety disorder, in the age range of eight to eighteen years, and 30 age- and sex-matched healthy controls. Heart-rate variability was studied using the standard protocol.

Results:

Significantly reduced variability of the heart rate was observed in both the time as well as frequency domains in the disorder group as compared to the control group. These findings indicate decreases in the sympathetic and parasympathetic activity in the disorder group, thus representing diminished physiological variability at rest.

Conclusions:

The notion of autonomic inflexibility, as seen in the current study, has important implications for stability in biological systems. The loss of variability in the physiological systems in general, and in the cardiovascular system in particular, has an association with a number of diseases and dysfunctions.

Clinical and autonomic functions: A study of childhood anxiety disorders

BACKGROUND AND OBJECTIVES

Childhood and adolescent anxiety is generally associated with a varied somatic symptom pattern thought to reflect autonomic system activity. Few studies have examined the autonomic characteristics of generalized anxiety disorder (GAD). This omission is at odds with contemporary models of autonomic cardiovascular control. The current study aimed to find differences in autonomic functions between children with a diagnosis of childhood anxiety disorder and a control group using a case-control design.

DESIGN AND SETTING

A cross sectional experimental study conducted in the years 2004-2005 in the psycho-physiology lab of a tertiary care multi-speciality teaching hospital.

METHODS

Assessments were carried out using a semistructured interview, K-SADS (Schedule for Affective Disorders and Schizophrenia for Children and Adolescents); STAIC (State and Trait Anxiety Inventory for Children); CDRS (Childhood Depression Rating Scales); SCARED (Self-Report for Childhood Anxiety-Related Disorders). Autonomic reactivity was tested using the standard battery of tests.

RESULTS

There were differences between 34 children and adolescents (age range, 8-18 years) with a diagnosis of childhood anxiety disorder and a control group of 30 age- and sex-matched subjects from a nearby school in autonomic activity and reactivity between individuals with anxiety disorder and non-anxious control subjects. Our finding is suggestive of autonomic rigidity or diminished physiologic flexibility in children with anxiety disorder.

CONCLUSIONS

The study is probably the first of its kind to look into the issue in detail using a detailed battery of the autonomic function tests, and the results are of help in better understanding the condition. The result of the present experiment supports differences in autonomic activity and reactivity between individuals with anxiety disorder and non-anxious control subjects.

Effect of Cushing's syndrome - Endogenous hypercortisolemia on cardiovascular autonomic functions

Cushing's syndrome is associated with increased cardiovascular morbidity and mortality. It's also associated with other cardiac risk factors like hypertension, diabetes mellitus and obesity. Cardiovascular autonomic function impairment could predict cardiovascular morbidity and mortality. Twenty five patients with Cushing's syndrome without diabetes and twenty five age matched healthy controls underwent a battery of cardiovascular autonomic function tests including deep breath test, Valsalva test, hand grip test, cold pressor test and response to standing from lying position. The rise in diastolic blood pressure on hand grip test and diastolic BP response to cold pressor test in Cushing's patients were significantly less compared to healthy controls (9.83 ± 3.90 vs 20.64 ± 9.55, p<0.001 and 10.09 ± 4.07 vs 15.33 ± 6.26, p<0.01 respectively). The E:I ratio on deep breathing test was also less in the patients in comparison to controls (1.36 ± 0.21 vs 1.53 ± 0.19, p<0.01). Seven patients underwent the same battery of tests 6 months after a curative surgery showing a trend towards normalization with significant improvement in expiratory to inspiratory ratio and sinus arrhythmia delta heart rate. To conclude, this study showed that chronic endogenous hypercortisolism in Cushing's is associated with an impaired sympathetic cardiovascular autonomic functioning. After a curative surgery, some of the parameters tend to improve.

Innovative method of needs assessment for faculty development programs in a Gulf medical school

BACKGROUND

Faculty development lays the foundation for the quality enhancement in medical education. However, programs are not always based on the needs of the participants, and there is dearth of information on methods to derive faculty's needs. The Medical Education Unit at the University of Dammam, Saudi Arabia, carried out an innovative method to identify and prioritize faculty needs in order to plan future activities.

METHODS

A questionnaire was designed, pilot-tested and administered to all faculty members (N=200). The respondents rated the perceived importance (high, moderate, low) and their performance (good, average, poor) on twelve competencies described in the literature. The ratings of perceived importance - high/moderate, and self-rated performance- average/poor, were summed up to determine priority rankings for continuing education. The respondents' rating of various continuing education activities, their willingness to participate and commit time, and their suggestions for strengthening faculty development were also analyzed.

RESULTS

All the twelve competencies were perceived as 'highly important' by the subjects. They felt most confident in teaching in large and small groups, attitudes and ethical values, and decision making skills. The competencies prioritized as "gaps" were knowing how to develop learning resources, plan curriculum, evaluate courses and conduct research. The prioritized activities were specialized courses, orientation workshops for the new faculty, and training in educational research skills. This implied a multi-phased approach to faculty development. A majority (62.4%) were willing to devote 2.2 hours per week to faculty development. Respondents suggested initiatives that should be undertaken by the Medical Education Unit and the broader institution.

CONCLUSION

We demonstrated a participatory approach to needs assessment by identifying the gaps between "perceived importance" and "self-rated performance", as criteria for determining priorities. Findings also demonstrated the need for adopting a comprehensive approach to faculty development in which both departmental and organizational initiatives are required. Our findings are applicable to the Gulf Region context and our methodology can be applied anywhere.

An improved windowing technique for heart rate variability power spectrum estimation

Spectral analysis of heart rate variability (HRV) is an accepted method for assessment of cardiac autonomic function and its relationship to numerous disorders and diseases. Discrete Fourier transform (DFT) based methods are widely used for their easy applicability, computational speed and the possibility for direct interpretation of results. This study assesses the limitation of windowing of the RR interval series of power spectrum estimation using DFT for heart rate variability studies. The mean value of the RR interval series should be subtracted before windowing. This may leave a small residual DC component after windowing, but the RR interval series is properly tapered to zero at the beginning and end of the window. However, if the windowed RR interval series has a non-zero mean then subtracting this mean will create an abrupt transition between the first and last data points, and the padded zeros. This is equivalent to superimposing upon the RR interval series a rectangular pulse of the same length as the window, with a height equal to the subtracted mean value. In the present paper an approach to overcome the above effects of the window in reducing the signal energy and introducing the low frequency component into spectrum has been suggested and incorporated. Result have been compared for DC biasing of windowed data spectrum, bias of windowed data removed by substraction of mean data, and data processed to remove windowed mean level and to maintain mean power. Thus the preprocessing of RR interval series with this method improves the accuracy of HRV analysis methods. The study was carried out by smoothing the complete RR interval series by single Hann window and by 50% overlapping the data segments of 256 data points followed by the DFT. Overlapping the data segments provides equal weight to all values in the RR interval series and smoothed spectral estimate with clearly dominant peaks in low- and high-frequency regions.

Occupational noise exposure in small scale hand tools manufacturing (forging) industry (SSI) in Northern India

Occupational noise has been recognized as hazardous for the human beings. A high noise level in forging shops is considered to lower the labour productivity and cause illness however occupational noise is being accepted as an integral part of the job. The present study has been carried out in 5 small scale hand tool forging units (SSI) of different sizes in Northern India in Punjab. Noise levels at various sections were measured. OSHA norms for hearing conservation has been incorporated which includes an exchange rate of 5 dB (A), criterion level at 90 dB (A), criterion time of 8 h, threshold level=80 dB (A), upper limit=140 dB (A) and with F/S response rate. Equivalent sound pressure level (L(eq)) has been measured in various sections of these plants. Noise at various sections like hammer section, cutting presses, punching, grinding and barrelling process was found to be >90 dB (A), which is greater than OSHA norms. A cross-sectional study on the basis of questionnaire has been carried out. The results of which revealed that 68% of the workers are not wearing ear protective equipments out of these 50% were not provided with PPE by the company. About 95% of the workers were suffering speech interference though high noise annoyance was reported by only 20%. It has been established that the maximum noise exposure is being taken by the workers as they are working more than 8h a day for six days per week. More than 90% workers are working 12 to 24 h over time per week which lead to very high noise exposure i.e. 50 to 80% per week higher than exposure time/week in USA or European countries(15, 16)).