Ashok Kumar Salhan

A computer based wireless system for online acquisition, monitoring and digital processing of ECG waveforms

Various ECG instruments have addressed a wide variety of clinical and technical issues. However, there is still scope for improvement in them particularly in the area of their susceptibility to noise, lack of universal connectivity and off-line processing. A prototype system has been developed that caters to these limitations. It includes an analog system and a FM transceiver pair interfaced through sound port of the computer. The real time acquired data is viewed and filtered using MATLAB software. The ECG system described captures the bio-signal faithfully in real time wireless mode with minimum noise and has universal connectivity.

Superpulsed (Ga‐As, 904 nm) low‐level laser therapy (LLLT) attenuates inflammatory response and enhances healing of burn wounds

Low-level laser therapy (LLLT) using superpulsed near-infrared light can penetrate deeper in the injured tissue and could allow non-pharmacological treatment for chronic wound healing. This study investigated the effects of superpulsed laser (Ga-As 904 nm, 200 ns pulse width; 100 Hz; 0.7 mW mean output power; 0.4 mW/cm(2) average irradiance; 0.2 J/cm(2) total fluence) on the healing of burn wounds in rats, and further explored the probable associated mechanisms of action. Irradiated group exhibited enhanced DNA, total protein, hydroxyproline and hexosamine contents compared to the control and silver sulfadiazine (reference care) treated groups. LLLT exhibited decreased TNF-α level and NF-kB, and up-regulated protein levels of VEGF, FGFR-1, HSP-60, HSP-90, HIF-1α and matrix metalloproteinases-2 and 9 compared to the controls. In conclusion, LLLT using superpulsed 904 nm laser reduced the inflammatory response and was able to enhance cellular proliferation, collagen deposition and wound contraction in the repair process of burn wounds. Photomicrographs showing no, absence inflammation and faster wound contraction in LLLT superpulsed (904 nm) laser treated burn wounds as compared to the non-irradiated control and silver sulfadiazine (SSD) ointment (reference care) treated wounds.

Online acquisition and wireless transmission of carotid pulse waveforms to analyse posture related changes

The physiological parameters of the fighter plane pilot undergo drastic changes leading to G stress accumulation. Heart rate is considered primary mechanism which plays a great role in acceleration protection research especially for G-LOC (G-induced loss of consciousness). Various methods based on various principles have been developed to study heart rate so far. Carotid pulse waveforms obtained from the human subject with the help of piezoelectric transducer may be used to analyse the cardiac activity. Change in heart rate due to change in the posture may be used to explain G stress effect on humans. Carotid signal is acquired by placing piezoelectric sensor based system on the subject’s carotid artery. The piezoelectric sensor has a transducing element which is efficient and effective to sense movement due to carotid pulse and produce piezoelectric signal data in response thereto. The real time data of carotid pulse waveforms of 12 human subjects are acquired and filtered using MATLAB software in various body postures. RR period and pulse amplitudes are quantified from real time recorded carotid signal by visual inspection. Further Statistical analysis is done to calculate the heart rate. The filtered stored data is transmitted wirelessly from one PC to another PC using Teamviewer software.

Evaluation of plasma hormone concentrations using Enzyme-Immunoassay/Enzyme-linked Immunosorbent assay in healthy Indian men: Effect of ethnicity.

The study involved three ethnic groups of India; Rajputs, Gorkhas and South-Indians. Each group consisted of ∼40 healthy, male soldiers between 20–50 years. The reference ranges for cortisol, testosterone, prolactin, arginine vasopressin and proAtrial natriuretic peptide1–98 were determined using Enzyme-Immunoassay (EIA) while plasma levels of thyroid-stimulating hormone, triiodothyronine, free-triiodothyronine, thyroxine and freethyroxine were measured using Enzyme-linked immunosorbent assay (ELISA). The results indicated that plasma hormone concentrations were within physiological range and inter-ethnic differences were most prominent between north- (Rajputs and Gorkhas) and south- Indians. In comparison to Radioimmunoassay, the EIA method for prolactin, thyroid-stimulating hormone, free-thyroxine gave higher values while the ELISA method for triiodothyronine, free-triiodothyronine, and thyroxine gave lower values. These differences are due to differences in assay standards and design.

Real time acquisition and PC to PC wireless transmission of human carotid pulse waveform

Carotid pulse is an established physiological parameter used to deduce cardiac information. Technological advances allow non-invasive measurement of carotid waveform, but involve complex electronics. Simple and relatively inexpensive method is devised here to acquire the carotid pulse. Measurements were made non-invasively on human subjects in various postures using piezoelectric sensor. Transducer output is interfaced directly to a computer in real time and carotid wave is viewed successfully on virtual oscilloscope. Stored data is digitally filtered, visually analyzed and transferred wirelessly from one computer to another using windows hyper-terminal and XBee RF transceiver module. Automated analysis algorithm can be further developed.

Acoustic analysis of speech under stress

When a person is emotionally charged, stress could be discerned in his voice. This paper presents a simplified and a non-invasive approach to detect psycho-physiological stress by monitoring the acoustic modifications during a stressful conversation. Voice database consists of audio clips from eight different popular FM broadcasts wherein the host of the show vexes the subjects who are otherwise unaware of the charade. The audio clips are obtained from real-life stressful conversations (no simulated emotions). Analysis is done using PRAAT software to evaluate mean fundamental frequency (F0) and formant frequencies (F1, F2, F3, F4) both in neutral and stressed state. Results suggest that F0 increases with stress; however, formant frequency decreases with stress. Comparison of Fourier and chirp spectra of short vowel segment shows that for relaxed speech, the two spectra are similar; however, for stressed speech, they differ in the high frequency range due to increased pitch modulation.

Impact of prolonged high altitude exposure on plasma prolactin in men: effect of age and ethnicity.

Hormonal changes during high-altitude (HA) exposure are important for normal adaptation to the new environment in lowlanders. Prolactin (PRL), a stress hormone, is involved in the regulation of fertility, immune response, osmotic balance, and angiogenesis. However, little is known about the effect of age and ethnicity on plasma PRL changes in men during prolonged HA exposure. The aim of this research was to examine possible age and ethnic variation in plasma PRL levels in men after 3 to 4 weeks of stay at HA (approximately 4500 m) in the Indian population. Lowlanders of Rajput (n = 49), Gorkha (n = 70), and South Indian (n = 40) ethnicities were studied at sea level (SL). They were taken to an altitude of approximately 4500 m where they stayed for 3 to 4 weeks. Another group of HA natives (Ladakhi, n = 65) was studied at similar altitude. Subjects were between 20 to 50 yr of age. At HA, plasma PRL showed a decrease in Rajputs and Gorkhas (p < 0.05), whereas there was an increase (p < 0.05) in South Indians when compared to SL. There was no age variation in PRL. PRL levels in HA natives were within the SL normal range observed in lowlanders. PRL response to HA stress in lowlanders is influenced by ethnicity. The exact cause for such differences in PRL secretion under HA stress is not clearly known. Further studies on the physiological regulation of PRL at HA are needed.

Real Time Acquisition of EMG Signal and Head Movement Recognition

paper presents the work on a technology for Real time EMG acquisition and recognition of head movement. EMG signal detection and analysis is useful in various clinical and biomedical applications such as generation of control signal for prosthetic tool, but better solutions for detecting noise free EMG signals need to be developed. In this paper a simple and cost effective method for estimating human head movements from neck EMG signals is proposed. In this work, surface EMG signal is acquired from four main neck muscles (right and left sternocleidomastoid muscles and right and left trapezius muscles) using simple computer interface and processed by MATLAB based filter algorithm for online clean display. Keywordsography, Real time acquisition, Muscle contractions

Plasma proANP1-98 Response During High Altitude Stress: Effect of Age and Ethnicity

OBJECTIVE Acclimatization to high altitude (HA) is accompanied by decrease in plasma atrial natriuretic peptide (ANP). On the other hand, circulating levels of the hormone are known to be influenced by age and ethnicity. The impact of these factors on ANP response during prolonged HA exposure remains unexplored. Hence, this study was conducted to examine possible age and ethnic variation in plasma proANP(1-98) levels in men after 3 to 4 weeks at HA. METHODS Lowlanders (LL) were studied at sea level (SL) and after 3 to 4 weeks at an altitude of approximately 4500 m. The LL group comprised Rajput (n = 48), Gorkha (n = 40), and South Indian (n = 43) ethnicities. Another group of HA natives (Ladakhi, n = 40) were studied at approximately 4500 m only. Subjects were between 20 and 50 years of age. Estimation of plasma proANP(1-98) and biochemical, hematologic, and physiologic evaluation was done. RESULTS In LL at HA, proANP(1-98) levels decreased (P < .001); plasma arginine vasopressin decreased (P < .05 in Rajputs and South Indians); and total protein, hemoglobin, and hematocrit increased (P < .05). Heart rate increased (P < .05), whereas arterial oxygen saturation decreased (P < .05) in all LL at HA. Ethnicity but not age variation in proANP(1-98) was observed under HA stress. In HA natives, plasma proANP(1-98) was higher than LL at HA and did not exhibit any age variation. CONCLUSIONS Plasma proANP(1-98) levels, reflecting medium-term ANP secretion, decrease during prolonged exposure to HA in LL. This is due to diuresis leading to plasma volume reduction that occurs during the acclimatization process. Ethnicity but not age variation is associated with plasma proANP(1-98) under HA stress.

A review of high G-stress induced problems and their solutions

G stress can debilitate pilots of modern fighter aircraft and consequence accidents due to G-induced loss of consciousness (G-LOC). The physiological effects of high G stress include reduction in head level blood pressure and cardiac output that subsequently results loss of vision and G-LOC. The bodys natural resistance system helps the pilot to fight against the effects of G stress to some level. To understand the medical and physiological consequences of high G forces on humans, research around the world is conducted using centrifuges, tilt tables, lower body negative pressure (LBNP) devices, etc. Physiological effects due to G-stress are experienced by the pilot on the cardiovascular, respiratory, musculoskeletal and central nervous systems. Many physiological, environmental and habitual conditions are found responsible for decreasing the G-tolerance. Mechanical, physiological and educational countermeasures are suggested to protect the pilots of high performance aircraft against the extreme acceleration. Expected inventions of more manoeuvrable aircrafts will possibly demand the use of advanced countermeasures to protect the pilots from the effect of high G forces.