Kishore Kumar Deepak

Assessment of heart rate variability derived from finger-tip photoplethysmography as compared to electrocardiography

Heart rate variability (HRV) is traditionally derived from RR interval time series of electrocardiography (ECG). Photoplethysmography (PPG) also reflects the cardiac rhythm since the mechanical activity of the heart is coupled to its electrical activity. Thus, theoretically, PPG can be used for determining the interval between successive heartbeats and heart rate variability. However, the PPG wave lags behind the ECG signal by the time required for transmission of pulse wave. In this study, finger-tip PPG and standard lead II ECG were recorded for five minutes from 10 healthy subjects at rest. The results showed a high correlation (median = 0.97) between the ECG-derived RR intervals and PPG-derived peak-to-peak (PP) intervals. PP variability was accurate (0.1 ms) as compared to RR variability. The time domain, frequency domain and Poincaré plot HRV parameters computed using RR interval method and PP interval method showed no significant differences (p < 0.05). The error analysis also showed insignificant differences between the HRV indices obtained by the two methods. Bland-Altman analysis showed high degree of agreement between the two methods for all the parameters of HRV. Thus, HRV can also be reliably estimated from the PPG based PP interval method.

Yogic Versus Conventional Treatment in Diarrhea-Predominant Irritable Bowel Syndrome: A Randomized Control Study

This study was conducted to evaluate the comparative effect of yogic and conventional treatment in diarrhea-predominant irritable bowel syndrome (IBS) in a randomized control design. The patients were 22 males, aged 20–50 years, with confirmed diagnosis of diarrhea-predominant IBS. The conventional group (n=12, 1 dropout) was given symptomatic treatment with loperamide 2–6 mg/day for 2 months, and the yogic intervention group (n=9) consisted of a set of 12 asanas (yogic poses, i.e., Vajrasana, Shashankasana, Ushtrasana, Marjariasana, Padhastasana, Dhanurasana, Trikonasana in two variations, Pawanmuktasana, and Paschimottanasana) along with Surya Nadi pranayama (right-nostril breathing) two times a day for 2 months. All participants were tested at three regular intervals, at the start of study—0 month, 1 month, and 2 months of receiving the intervention—and were investigated for bowel symptoms, autonomic symptoms, autonomic reactivity (battery of five standard tests), surface electrogastrography, anxiety profile by Spielbergers Self Evaluation Questionnaire, which evaluated trait and state anxiety. Two months of both conventional and yogic intervention showed a significant decrease of bowel symptoms and state anxiety. This was accompanied by an increase in electrophysiologically recorded gastric activity in the conventional intervention group and enhanced parasympathetic reactivity, as measured by heart rate parameters, in yogic intervention group. The study indicates a beneficial effect of yogic intervention over conventional treatment in diarrhea-predominant IBS.

Cardiovascular autonomic functions in well-controlled and intractable partial epilepsies.

BACKGROUND Epilepsy is associated with imbalance of sympathetic and parasympathetic activity which may lead to sudden unexplained death in epilepsy (SUDEP). Well-controlled (WcE) and intractable epilepsy (IE) subjects may present different autonomic profiles, which can be helpful in explaining the predisposition of the latter to SUDEP. PURPOSE To compare inter-ictal cardiovascular autonomic function in subjects with partial WcE and IE. METHODS Thirty WcE and 31 IE subjects underwent a battery of autonomic function tests: deep breathing, Valsalva maneuver, isometric exercise, cold pressor and tilt-table. Autonomic tone was assessed by heart rate variability (HRV). Their autonomic severity score and anxiety status was also assessed. RESULTS IE subjects had elevated low frequency component (52.0 vs. 37.6, p=0.047) and decremented high frequency component (114 vs. 397, p=0.013) of HRV and higher diastolic BP (75.62+/-9.77 vs. 68.64+/-0.43, p=0.036). In deep breathing test, they had lesser HR changes (20+/-10.18 vs. 29.68+/-11.23, p=0.007) and lower E:I (1.29+/-0.16 vs. 1.43+/-0.21, p=0.008). IE subjects had higher dysautonomia (chi square 165.0, p<0.0001). CONCLUSIONS We observed a higher vasomotor tone, higher sympathetic tone, lower parasympathetic tone, lower parasympathetic reactivity and more severe dysautonomia in the IE subjects. Refractoriness may lead to an alteration in cardiovascular autonomic regulation, which might be a predisposing factor for SUDEP.

The efficacy of a comprehensive lifestyle modification programme based on yoga in the management of bronchial asthma: a randomized controlled trial

BackgroundThere is a substantial body of evidence on the efficacy of yoga in the management of bronchial asthma. Many studies have reported, as the effects of yoga on bronchial asthma, significant improvements in pulmonary functions, quality of life and reduction in airway hyper-reactivity, frequency of attacks and medication use. In addition, a few studies have attempted to understand the effects of yoga on exercise-induced bronchoconstriction (EIB) or exercise tolerance capacity. However, none of these studies has investigated any immunological mechanisms by which yoga improves these variables in bronchial asthma.MethodsThe present randomized controlled trial (RCT) was conducted on 57 adult subjects with mild or moderate bronchial asthma who were allocated randomly to either the yoga (intervention) group (n = 29) or the wait-listed control group (n = 28). The control group received only conventional care and the yoga group received an intervention based on yoga, in addition to the conventional care. The intervention consisted of 2-wk supervised training in lifestyle modification and stress management based on yoga followed by closely monitored continuation of the practices at home for 6-wk. The outcome measures were assessed in both the groups at 0 wk (baseline), 2, 4 and 8 wk by using Generalized Linear Model (GLM) repeated measures followed by post-hoc analysis.ResultsIn the yoga group, there was a steady and progressive improvement in pulmonary function, the change being statistically significant in case of the first second of forced expiratory volume (FEV1) at 8 wk, and peak expiratory flow rate (PEFR) at 2, 4 and 8 wk as compared to the corresponding baseline values. There was a significant reduction in EIB in the yoga group. However, there was no corresponding reduction in the urinary prostaglandin D2 metabolite (11β prostaglandin F2α) levels in response to the exercise challenge. There was also no significant change in serum eosinophilic cationic protein levels during the 8-wk study period in either group. There was a significant improvement in Asthma Quality of Life (AQOL) scores in both groups over the 8-wk study period. But the improvement was achieved earlier and was more complete in the yoga group. The number-needed-to-treat worked out to be 1.82 for the total AQOL score. An improvement in total AQOL score was greater than the minimal important difference and the same outcome was achieved for the sub-domains of the AQOL. The frequency of rescue medication use showed a significant decrease over the study period in both the groups. However, the decrease was achieved relatively earlier and was more marked in the yoga group than in the control group.ConclusionThe present RCT has demonstrated that adding the mind-body approach of yoga to the predominantly physical approach of conventional care results in measurable improvement in subjective as well as objective outcomes in bronchial asthma. The trial supports the efficacy of yoga in the management of bronchial asthma. However, the preliminary efforts made towards working out the mechanism of action of the intervention have not thrown much light on how yoga works in bronchial asthma.Trial registrationCurrent Controlled Trials ISRCTN00815962

Meditation improves clinicoelectroencephalographic measures in drug-resistant epileptics

Eleven adults suffering from drug-resistant epilepsies were given meditation practice, while another nine adults acted as waiting list controls. All patients were on antiepileptic drugs and their serum drug levels were monitored regularly. Patients in the intervention group were given training in meditation, and they practiced meditation 20 minutes a day for one year. They showed a significant reduction in seizure frequency and duration, an increase in the dominant background EEG frequency, a reduction in mean spectral intensity of the 0.7-7.7 Hz segment, and an increment in mean spectral intensity in the 8–12 Hz segment of the EEG. All changes were statistically significant. Control patients did not show significant changes in seizure frequency and duration during the observation period of one year. The results indicate that continued meditation practice is of substantial help in improving the clinicoelectrographic picture in drug-resistant epileptics.

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.

Specific muscle EMG biofeedback for hand dystonia.

Currently available therapies have only limited success in patients having hand dystonia (writers cramp). We employed specific muscle EMG biofeedback (audio feedback of the EMG from proximal large muscles of the limb that show abnormally high activity during writing) in 10 of 13 consecutive patients (age, 19–62 years; all males) with a duration of illness from 6 months to 8 years. In three patients, biofeedback was not applicable due to lack of abnormal EMG values. Nine patients showed dystonic posture during writing and had hypertrophy of one or more large muscles of the dominant hand. The remaining four patients showed either involvement of small muscles or muscle wasting. Ten patients were given four or more sessions of EMG audio biofeedback from the proximal large limb muscles, which showed maximum EMG activity. They also practiced writing daily with the relaxed limb for 5 to 10 min. Nine patients showed improvement from 37 to 93% in handwriting, alleviation of discomfort, and pain (assessed on a visual analogue scale). One patient did not show any improvement. Thus EMG biofeedback improved the clinical and electromyographic picture in those patients with hand dystonia who showed EMG overactivity of proximal limb muscles during writing. This specific type of EMG biofeedback appears to be a promising tool for hand dystonia and might also be applied to other types of dystonias.

Autonomic dysfunctions in patients with inflammatory bowel disease in clinical remission.

Introduction and Objective The autonomic nervous system, especially the parasympathetic system, has been reported to modulate the immune response in chronic inflammatory disorders. Autonomic dysfunctions have been reported earlier in patients with inflammatory bowel disease; however, the results have been conflicting. We therefore evaluated autonomic functions in patients with inflammatory bowel disease (IBD) in clinical remission. Patients and Methods Heart rate variability, a marker of autonomic functions, which included time-domain, frequency-domain, and nonlinear indices (Poincaré plot) was assessed using Nevrokard, version 6.4.0 Slovenia, in 118 patients with IBD (ulcerative colitis [UC] 62, and Crohn’s disease [CD] 56) and 58 healthy controls. Results There was no difference in mean of R–R intervals in patients with UC, CD, and healthy controls. Frequency domain indices (absolute values of total power, high-frequency power, and low-frequency power) were lower in patients with UC and CD vs. healthy controls. High-frequency (HFnu) (expressed in normalized units) was significantly lower in UC compared to healthy controls. There was no significant difference in the low-frequency (LFnu) and LF/HF ratio in UC, CD, and healthy controls. Amongst the Poincaré plot indices, while standard deviation of the instantaneous R–R interval variability (SD1nu) was lower in UC and CD vs. healthy controls, there was no significant difference in the long-term R–R interval variability (SD2nu). Conclusions Patients with inflammatory bowel disease have lower autonomic functions. Patients with UC have significantly lower parasympathetic function in comparison to those with CD and healthy controls. These autonomic dysfunctions in patients with IBD may have a bearing on the pathogenesis of IBD.

Comparison of symptomatic and asymptomatic, chronic, primary angle-closure glaucoma, open-angle glaucoma, and controls.

Purpose: To determine the clinical features and anatomic parameters in asymptomatic (creeping) and symptomatic, chronic, primary angle‐closure glaucoma (PACG) as compared with open‐angle glaucoma (OAG) and with control subjects with normal eyes. Methods: Forty consecutive patients with each of the following four types of eyes were studied (N = 160): eyes with symptomatic PACG, eyes with asymptomatic PACG, eyes with OAG, and the eyes of age‐, sex‐, and refraction‐matched control subjects. The refractive status, keratometry, pachymetry, corneal diameter, anterior chamber depth, lens thickness, axial length, and relative lens position were noted. The groups were compared using a paired t test and analysis of variance. Results: Patients with asymptomatic chronic PACG were older than patients in the symptomatic group, were more often men, and were more likely to have either diabetes mellitus or hypertension. Symptomatic chronic PACG eyes were more hypermetropic. Asymptomatic eyes had more iridotrabecular synechiae and minimal pupillary ruff atrophy as compared with the symptomatic eyes that had largely iridocorneal synechiae and large areas where the ruff was absent. All other clinical and anatomic parameters were statistically similar in the two groups, but differed significantly from OAG and control eyes. Conclusions: The ocular parameters of asymptomatic or creeping angle closure eyes show that these are significantly different from eyes having POAG. Asymptomatic and symptomatic chronic PACG eyes are structurally similar. Open‐angle glaucoma eyes and normal eyes were comparable, but differed from both the chronic angle‐closure glaucoma groups in having a larger corneal diameter, deeper anterior chamber, thinner lens, and a longer axial length. The symptomatic chronic PACG eyes showed more evidence of ischemic damage to the iris, and this could account for the symptoms reported by these patients.

Effects of RR segment duration on HRV spectrum estimation

Although patterns of heart rate variability (HRV) hold considerable promise for clarifying issues in clinical applications, the inappropriate quantification and interpretation of these patterns may obscure critical issues or relationships and may impede rather than foster the development of clinical applications. The duration of the RR interval series is not a matter of convenience but a fine balance between two important issues: acceptable variance and stationarity of the time series on one hand, and acceptable resolution of the spectral estimate and reduced spectral leakage on the other. Further, in the standard short-term HRV analysis, it has been observed that the previous studies in HRV spectral analysis use a wide range of RR interval segment duration for spectral estimation by Welchs algorithm. The standardization of RR interval segment duration is also important for comparisons among studies and is essential for within-study experimental contrasts. In the present study, a comparative analysis for RR interval segment durations has been made to propose an optimal RR interval segment duration. Firstly a simulated signal was analyzed with Hann window and zero padding for the segment lengths of 1024, 512, 256 and 128 samples resampled at 4 Hz with 50% overlapping. Again, the above procedure was applied to RR interval series and it was concluded that segment length of 256 samples with 50% overlapping provides a smoothed spectral estimate with clearly outlined peaks in low- and high-frequency bands. This easily understandable and interpretable spectral estimate leads to a better visual and automated analysis, which is not only desirable in basic physiology studies, but also a prerequisite for a widespread utilization of frequency domain techniques in clinical studies, where simplicity and effectiveness of information are of primary importance.