Heart Rate Variabilty Changes During First Week of Acclimatization to 3500 M Altitude in Indian Military Personnel.

Acute exposure to hypobaric hypoxia induces the changes in autonomic control of heart rate. Due to emergencies or war like conditions, rapid deployment of Indian military personnel into high altitude frequently occurs. Rapid deployment to high altitude soldiers are at risk of developing high altitude sickness. The present study was conducted to evaluate the acute exposure to high altitude hypobaric hypoxia (3500 m altitude) on the autonomic nervous control of heart rate in Indian military personnel during first week of acclimatization Indices of heart rate variability (viz; R-R interval, total power, low frequency, high frequency, ratio of low to high frequency) and pulse arterial oxygen saturation were measured at sea level and 3500m altitude. Power spectrum of heart rate variability was quantified by low frequency (LF : 0.04-0.15 HZ) and high frequency ( HF : 0.15-0.5 HZ) widths. The ratio of LF to HF was also assessed as an index of the sympathovagal balance. Mean R-R interval decreased significantly on day 2 on induction to altitude which tended to increase on day 5. Total power (TP) decreased high altitude and tended to recover within a week. Both HF and LF power showed decrement at 3500m in comparison to sea level. The ratio of LF to HF (LF/HF) at 3500m was significantly higher at 3500m. SpO2 values decreased significantly (P<0.05) at high altitude on day-2 which increased on day-5. We conclude that autonomic control of the heart rate measured by heart rate variability was altered on acute induction to 3500m which showed a significant decrease in parasympathetic tone and increase in sympathetic tone, then acclimatization seems to be characterized by progressive shift toward a higher parasympathetic tone.

Chronic low dose exposure to hydrogen peroxide changes sensitivity of V79 cells to different damaging agents.

Chinese hamster V79 cells were repeatedly exposed to a low dose of hydrogen peroxide (H2O2) over several weeks and then exposed to H2O2, cisplatin or ultraviolet (UV) light. Cell killing was examined by colony formation, following these treatments. It was seen that cells conditioned by multiple low doses of H2O2 showed resistance to killing in case of H2O2 and cisplatin but the sensitivity to UV light was same as the control cells. Apoptosis was also determined in these cells after the same treatments. UV light failed to induce apoptosis in both conditioned and in control cells, but in case of cells treated with H2O2 and with cisplatin, there was less apoptosis in the conditioned cells compared to the control cells. From our observation we can say that the enhanced survival of cells after treatment with H2O2 or cisplatin could be due to inhibition of apoptosis.

Oxygen saturation response to exercise VO2 at 2100 m and 4350 m in women mountaineering trainees.

Human work performances decreases at high altitude (HA). This decrement does not appear to be similar for every individual, may be due to variety of factors like elevation, mode of induction, work intensity, physical condition and specificity of the subjects. The purpose of the study was to evaluate the effects of alteration in responses of oxygen saturation (SaO2) and oxygen consumption (VO2) to a standard exercise in women mountaineering trainees under hypobaric hypoxia. Experiments were conducted in 2 groups (10 each) of females and compared the difference in responses of native women of moderate altitude with those of the plains/low altitude. A standard exercise test (Modified Harvard Step-Test for women) was performed on a 30 cm stool with 24 cycles/min for 5 min, initially at 2100 m and then at 4350 m. The exercise VO2 values for plains dwelling women achieved apparently VO2max level at both altitude locations with significant reduction in SaO2 during standard exercise. Exercise VO2 values decreased on exposure to 4350 m with further reduction in SaO2. Whereas with same work intensity, under same situation the exercise VO2 values of the moderate altitude women did not appear to have reached VO2max. They also maintained comparatively higher level of SaO2. It may be concluded that hypoxic exposure along with mountaineering training, the moderate altitude women maintained a higher level of SaO2 during standard exercise at both altitude locations, compared to low altitude women who might have lost a compensatory reserve to defend the hypoxic stress to exercise. Thus, moderate altitude women are proved to be better fit for hypoxic tolerance/HA performance.

Immediate treatment of frostbite using rapid rewarming in tea decoction followed by combined therapy of pentoxifylline, aspirin & vitamin C.

BACKGROUND & OBJECTIVES: Frostbite, the severest form of cold injury is a serious medical problem for our Armed Forces operating in the snow bound areas at high altitude. Effects of treatment by rapid rewarming in tea decoction followed by combined therapy of pentoxifylline, aspirin and vitamin C were evaluated in amelioration of tissue damage due to experimentally induced frostbite in rats. METHODS: Experiments were conducted in 2 groups (25 each) of albino rats (control i.e., untreated and experimental i.e., treated). Frostbite was produced experimentally in all the animals by exposing one of the hind limbs at -12 +/- 1 degree C with wind flow 25-30 lit/min for 30 min in a freezing-machine, with simultaneous recordings of rectal and ambient temperatures. The degree of tissue damage was assessed after 10 days. Following cold exposure, neither external thawing nor any medication was given to the animals of the control group; while the exposed limb of the experimental animals was rewarmed in tea decoction maintained at 37-39 degrees C for 30 min immediately after cold exposure, with simultaneous oral ingestion of warm tea decoction. These animals were also given pentoxifylline (40 mg/kg), aspirin (5 mg/kg) and vitamin C (50 mg/kg) twice daily orally for the next 7 days. RESULTS: In the control group, 68 per cent animals suffered from severe (56%) to very severe (12%) frostbite, while the remaining 32 per cent had moderate frostbite. No animals of this group could escape injury or suffered anything less than moderate frostbite; whereas 52 per cent of experimental animals escaped injury (no frostbite) and 32 and 16 per cent suffered only with primary and moderate degree of injury, respectively. None from this group suffered from severe or very severe frostbite. INTERPRETATION & CONCLUSION: It is evident from the study that this combined therapy resulted in significant improvement in the degree of tissue preservation and proved to be highly beneficial as an immediate treatment of frostbite in rats. The combined pharmacological properties of these drugs might have altered the haemorrheologic status of blood and produced curative beneficial effect in improving tissue survival. Clinical studies are required for confirmation of these beneficial effects in humans, which has already been taken up.