K K Deepak

IIT Delhi & All India Institute of Medical Sciences, New Delhi India

Background Neuroinflammation, neuronal cytotoxicity, and apoptosis due to exposure to anaesthetic agents are often implicated in postoperative cognitive dysfunction (POCD). Lidocaine and dexmedetomidine have been shown to suppress the neuron-specific markers of inflammation, and we aimed to compare their neuroprotective efficacy in elderly patients...

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...

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...

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...

Skeletal muscle atonia is a prominent feature of rapid eye movement sleep. Neuromuscular junction exhibits high morphological and functional plasticity. Sleep deprivation (SD) may influence NMJ morphology at presynaptic and postsynaptic terminals levels. In the present study, we have looked into the ultrastructural changes in the rat soleus muscle...

Sleep is essential for the cellular, organic and systemic functions of an organism. Sleep deprivation is associated with metabolic dysfunction and ageing is so. Muscle health at elderly age is one of the major risk factor. Poor muscle health is associated with a series of chronic and metabolic conditions that are prevalent in individuals who chroni...

Skeletal muscle atonia is a prominent feature of rapid eye movement sleep. Neuromuscular junction exhibits high morphological and functional plasticity. Sleep deprivation (SD) may influence NMJ morphology at presynaptic and postsynaptic terminals levels. In the present study, we have looked into the ultrastructural changes in the rat soleus muscle...

Sleep is essential for the cellular, organic and systemic functions of an organism. Sleep deprivation is associated with metabolic dysfunction and ageing is so. Muscle health at elderly age is one of the major risk factor. Poor muscle health is associated with a series of chronic and metabolic conditions that are prevalent in individuals who chroni...

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 i...

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...

This paper investigates the correlation between linear and non-linear features of short-term heart rhythm fluctuations during internally and externally operative attention. Posner’s spatial cueing paradigm was used with internal and external peripheral cueing, which provided comprehensive heart beat intervals for analysis. Heart rhythms were acquir...

https://www.frontiersin.org/books/Proceedings_of_the_2021_ISGP_Meeting/5013

Objectives: To evaluate the autonomic function in specific learning disorder (SLD) and comorbid SLD attention-deficit hyperactivity disorder (SLD-ADHD). Methods: A cross-sectional study was conducted in a tertiary care hospital with 20 adolescent subjects each of confirmed SLD, SLD-ADHD, and healthy control (mean age 15.32 y). Heart-rate variabi...

In the study, quantitative analysis was done to identify the interaction among cardiac, vascular and respiratory signals for 6-degree head-down tilt (HDT) microgravity analogue. This HDT shifts the blood volume towards the thoracic cavity of the human body. The linear and non-linear domain analyses are based on coherence techniques that are used to...

Computational fluid dynamics (CFD) has been an effective tool for obtaining insight into the circulatory system’s physical functioning. Herein, we evaluate the blood flow throughout the human right carotid artery in weightlessness and earth gravity environments. The 3D carotid artery design was developed in Creo, and Ansys Fluent was used to analyz...

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...

Objectives Gravity plays an important role in the day-to-day functioning of the cardiovascular system (CVS) in the human body. The absence of gravity severely affects CVS functioning. Out of existing simulation models of microgravity, the 6° head-down tilt (HDT) is frequently used analog to replicate the physiological effects of microgravity on ear...

Muscle atrophy in humans mainly occurs due to aging, lack of physical activity, and exposure to microgravity leading to decreased muscle volume and power. Several exercises coupled with various bodysuits have been used to cope with muscle atrophy. But, all state of arts failed to provide complete prevention from atrophy. Hence, a new countermeasure...

Consequent to the unprecedented COVID-19 pandemic, pedagogic changes were introduced in postgraduate courses in Physiology, where face-to-face teaching was replaced with synchronous virtual mode for leader-centered (seminar, symposium) and participant-centered (journal club, group discussion) academic activities. We hypothesized that the effectiven...

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 practiti...

Lower body negative pressure (LBNP) has been employed in multiple countermeasure protocols against post spaceflight orthostatic hypotension. However, protocols utilizing oscillatory LBNP (oLBNP) have not been explored in this regard. oLBNP has shown promise in few studies to have good tolerance in conditions of hypovolemic stress and since the nega...

Muscle atrophy occurs in human musculature system due to inactivity of muscles in microgravity environment. Herein, a novel designed countermeasure gravitational load modulation bodygear is developed to enhance muscle activity. The bodygear is devised to compress the body through axial loading from shoulder to feet. The time and frequency domain pa...

Background Sudoku is a popular cognitively stimulating leisure-time activity. Many studies have been directed toward finding an algorithm to solve Sudoku, but the investigation of the neural substrates involved in Sudoku has been challenging. Methods Sudoku task was divided into two steps to understand the differential function of the prefrontal c...

Objective: Spinocerebellar ataxia (SCA) is a neurodegenerative disorder in which, autonomic dysfunction is a common manifestation. Brain area atrophy also involves the areas comprising central autonomic net�work (CAN) in SCA. Structural atrophy of CAN and autonomic dysfunction should go hand in hand. But this important relationship has not been stu...

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 pat...

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 han...

This study identifies a correlation between low-frequency heart rate variability (LF-HRV) and encephalographic (EEG) complexity to differentiate internally operative attention (INT) and externally operative attention (EXT). Electrophysiological fluctuations in response to Posner’s spatial orienting paradigm were explored in 14 healthy volunteers wh...

Heart and brain recurrently interact to mediate human cognitive information processing. This chapter identifies nonlinear variations of heart activities acquired during internally and externally operative attention using multifractal analysis. Fourteen healthy subjects voluntarily participated in the experiment designed as per Posner’s spatial cuei...

The autonomic nervous system (ANS) is one of the effector pathways for circadian variation of many physiological parameters. Autonomic tone and airways caliber have been reported to exhibit circadian variation in separate studies. A simultaneous investigation of heart rate variability (HRV) and airway caliber might ascertain how airway caliber is m...

Non‐segmental generalized vitiligo (NSGV) is the most common and progressive clinical form of vitiligo1 and NB‐UVB is most preferred and effective treatment modality in aNSGV.2 Effect of NB‐UVB treatment on micro RNA (miRNA) expression and its association with clinical outcome in active NSGV (aNSGV) is not known. miRNA are non‐coding oligonucleotid...

Typical a 4-month missions to the Space Station (SS) leads to significant cardiovascular deconditioning, bone demineralization and muscle atrophy. Performing space experiment on earth is a very difficult task. There is various way through which microgravity experiment conducted on earth such as 6o head down tilt (HDT), dry floatation and water floa...

Heart and brain interactions mediate human cognition. This investigation identifies heart-brain interactions during internally operative attention (AI) and externally operative attention (AE). AI attention involves short term memory, whereas AE attention deals with automatic and transient response to objects in the external world. A modified Posner...

Abstract—Computational fluid dynamics (CFD) has become an influential tool which gains insight into the physical performance of the circulatory system. Cardiovascular disease received less attention from a computational viewpoint. The present work analyses the blood flow in common carotid artery with fat deposition and without fat deposition. The c...

This paper investigates the correlation between linear and non-linear features of short-term heart rhythm fluctuations during internally and externally operative attention. Posner’s spatial cueing paradigm was used with internal and external peripheral cueing, which provided comprehensive heart-beat intervals for analysis. Heart rhythms were acquir...

In the study, Granger causality frequency analysis based on directed coherence is utilized to detect and quantify directional interaction among heart rate, systolic blood pressure and respiratory signal during postural stress from supine to standing and from standing to supine. The directional information flow during postural stress from supine to...

Conventional analysis of motor-evoked potential (MEP) is performed in time domain using amplitude and latency, which encapsulates information relevant to the cortical excitability of the brain. The study investigated the importance of time-frequency analysis by comparing MEPs in time-frequency domains (TFD) of healthy versus stroke survivors. Six h...

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 pa...

Computational fluid dynamics becomes an influential tool which gains insight into the physical performance of the circulatory system. Cardiovascular disease received less attention from a computational viewpoint; the present work analyses the blood flow in common carotid artery in head down tilt position. The common carotid artery has complex geome...

Objectives: To assess the time and frequency domain measures of cardiac autonomic activity/tone in patients of genetically defined spinocerebellar ataxia (SCA) types 1 and 2, as well as to decipher the probable associations among the cardiovascular autonomic parameters and genetic and clinical characteristics. Materials and methods- Simultaneous 5...

In this study, heart rate time series have been investigated to assess the presence of scale invariance property of a signal. The electrocardiogram signal is recording from Biopac MP100 system during postural shift from supine to standing. Heart rate time series is extracted from electrocardiogram signal and is analyzed using detrended fluctuation...

Purpose To detect and quantify the directional interaction changes between cardio-respiratory system during postural change. Method Traditional frequency domain analysis based on power spectrum and coherence are insufficient to quantify nonlinear structures and complexity of physiological subsystems. Recently, Granger causality is found as prefera...

Finite element method (FEM) is a method of answer of the boundary value problems. Finite element analysis (FEA) is the applied application of FEM. The obtained results are important in understanding the knee stiffness. Stiffness results in outward movement of knee which can create poor locomotion.

Purpose of the study: Demonstration of nerve-muscle experiments play a vital role for teaching Physiology to undergraduate medical students. In recent days, procuring frogs for the conduction of these experiments have become a major concern. Therefore, we have designed an innovative method to carry out nerve-muscle Physiology experiments in human s...

Introduction/Background Fibromyalgia (FM) is a multi-symptomatic disorder with a varying degree of widespread pain in the body. With emerging evidences pathophysiological concept shifted from peripheral damage or inflammation to central neural mechanism. Fibromyalgia is characterised by dysfunction in central pain processing, “central sensitivity”....

Lower body negative pressure (LBNP) technique has been used for simulating orthostasis by producing preload reduction. Valsalva maneuver (VM), a commonly employed test for autonomic function evaluation, operates on similar principle. Previous literature recommends LBNP as a substitute to VM but has not compared them from a baroreflex perspective. W...

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 st...

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 alterin...

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 us...

Background and purpose: Refractory temporal lobe epilepsy (TLE) is commonly associated with imbalances in cardiovascular (CV) parasympathetic and sympathetic functions, which are treated using TLE surgery. We investigated the effect of hemispheric lateralization of seizure foci on autonomic CV functions before and after TLE surgery. Methods: The...

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...

Spinocerebellar ataxia (SCA) is a progressive neurodegenerative disorder characterized by autonomic dysfunction. SCA has multiple genetically classified subtypes, amongst which SCA1 and SCA2 are most prevalent in India. Autonomic function based characterization of SCA patients into respective subtypes has not been done. We have evaluated autonomic...

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 do...

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 i...

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

Objectives: Baroreceptor sensitivity (BRS), a functional consequence of vascular stiffness, may be affected by the presence of diabetes mellitus (DM) and nonalcoholic fatty liver disease (NAFLD). The present study was designed to assess the effect of diabetic status and NAFLD grade on the BRS in patients with NAFLD. Methods: Seventy-five individ...

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 seizur...

Aim. The present study was designed to evaluate the heart rate variability (HRV) in nonalcoholic fatty liver disease (NAFLD) and to assess the effect of grade of NAFLD and diabetic status on HRV. Methods. This cross-sectional study included 75 subjects (25 NAFLD without diabetes, 25 NAFLD with diabetes, and 25 controls). Measurements included anthr...

Purpose of the study: Systemic and local regulation of peripheral circulation is a vital concept to be taught to undergraduate medical students. There is lack of an effective practical module to demonstrate and reinforce the theoretical understanding of this concept. Methodology: We designed a simple feasible novel practical using finger pulse r...

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...

Prader-Willi syndrome is a classical hypothalamic insufficiency disorder. This syndrome is often associated with cardiovascular morbidity and mortality - which could probably be attributed to autonomic dysfunction. A 21-year-old Prader Willi syndrome patient was referred for cardiovascular and autonomic function assessment. We performed a battery o...

Introduction Blood volume is an important determinant of the efficacy of the negative feedback mechanisms that maintain blood pressure. However, its effect on time profile and magnitude of the responses remain unstudied. Aim To study the effect of mild hypovolemia on time profiles and magnitude of changes in blood pressure and heart rate in healthy...

Aim: The study was aimed to assess the knowledge on understanding ethical authorship of research publications among the medical and pharmacy faculty members of India. Materials and Methods: We have selected 54 numbers of medical faculty members and 41 numbers of pharmacy faculty members from different parts of India to assess their understanding an...

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) a...

Obesity and insulin resistance (IR) are associated with type 2 diabetes mellitus (DM). Obesity can be quantified by body mass index (BMI) and waist circumference (WC). Similarly, IR is commonly quantified by fasting-plasma-insulin (FPI) and Homeostatic model assessment (HOMA-IR). We aimed our study to find correlation between obesity-parameters and...

Abstract Cardiac autonomic dysfunction is an independent determinant of adverse outcomes in many diseases. The available literature on the relative changes in sympathetic and parasympathetic components in chronic obstructive pulmonary disease (COPD) is equivocal, the clinical and physiological correlates are poorly defined and association with mark...

The objective of the study was to observe the effect of controlled breathing exercises including Sudarshan Kriya (SK) and Prana-Yoga (PY) on the psycho-physiological status. The study group included 60 healthy volunteers (M:30, F:30) in the age group of 18 to 30 years (21.3 ± 3.2 yrs), randomly divided in to three groups of 20 subjects each--(1) Th...

One month of yoga training has been shown to reduce the pulse rate voluntarily without using external cues. Hence, the present study was designed to understand the strategies used by yoga practitioners and autonomic changes associated with voluntary heart rate reduction. Fifty volunteers (group mean age ± S.D., 25.4 ± 4.8 years; 25 males) were asse...

With the global liberalization industries in India are growing at a very fast pace, especially the small and medium enterprises (SMEs) like; foundries, mining industries, food processing industries etc. But due to lack of use of advanced technologies by SMEs, the labourers are exposed to dusty and hazardous environment and they are getting more pro...

Approximate entropy (ApEn) and sample entropy (SampEn) are the promising techniques for extracting complex characteristics of cardiovascular variability. Ectopic beats, originating from other than the normal site, are the artefacts contributing a serious limitation to heart rate variability (HRV) analysis. The approaches like deletion and interpola...

Autonomic symptoms frequently occur during seizures. There are reports that the adult group of intractable epilepsy patients have different autonomic profile than the well controlled epilepsy, but there is no clear evidence in the children epilepsy group, therefore, we planned to study the autonomic profile in well controlled and refractory epileps...

Aims and Objectives: To assess the effect of Comprehensive Yogic Breathing Program on glycemic control, quality of life, and cardiac autonomic functions in diabetes. Material and Methods: This is a prospective randomized controlled intervention trial. Cardiac autonomic functions were assessed in 120 diabetics. Patients were randomized into two grou...

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 mel...

Patients of orthostatic hypotension may or may not have symptoms of the cerebral hypoperfusion despite fall in the blood pressure. The present study was done to quantify autonomic functions and cerebral autoregulation in patients of orthostatic hypotension with or without symptoms. The study was conducted in 15 patients of orthostatic hypotension a...

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

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...

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...

In this paper an over-complete discrete wavelet transform (OCDWT) algorithm, obtained by blending two wavelet transform implementations that is redundant wavelet transform and the Mallat's multiresolution decomposition, has been proposed to retrieve the time-varying characteristics of HRV under two different postures, supine and standing. The OCDWT...

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. To compare inter-ictal...

Photoplethysmogram (PPG) measures have been proven useful for the quantification of sympathetic reactivity and continuous monitoring of vascular reactivity. This study was designed to delineate the influence of respiratory rate on the variability of various PPG characteristics in time and frequency domains. PPG, electrocardiogram (ECG) and respirat...