Metabolic syndrome and carotid artery intima-media thickness in military pilots.

BACKGROUND: The common carotid artery intima-media thickness (CCAIMT) is an independent predictor of cardiovascular events and diabetes mellitus in apparently healthy men. The relationship between features of metabolic syndrome (MS) and CCAIMT is not fully understood. We conducted this study to assess the cross-sectional relationship between CCAIMT and MS parameters in military pilots during their regular annual medical physical examinations. METHODS: There were 179 pilots (ages 39.69 +/- 5.56 yr) free of cardiovascular disease and diabetes mellitus included in our study. MS was defined according to the International Diabetes Federation criteria. The CCAIMT was measured in the posterior wall of both common carotid arteries within 1 cm proximal to the carotid bulbus, by high-resolution B-mode ultrasonography. RESULTS: We identified MS in 51 (28.5%) and CCAIMT > or = 0.9 mm in 72.1% of subjects, and found the means of CCAIMT in subjects grouped according to the absence and presence of 3, 4, and 5 MS features to be 0.98, 1.05, 1.14, and 1.18 mm respectively, with statistically significant differences between those without and those with 4 and 5 components, as well as between those with MS and those with 5 MS features. A simple logistic regression analyses showed that HDL-c, triglycerides, triglycerides/HDL-c, pulse pressure, and smoking were not associated with CCAIMT > or = 0.9 mm, while multiple logistic regression analysis indicated that total cholesterol and body mass index were independent predictors of CCAIMT. CONCLUSIONS: The increase in MS features in our study group correlated with the increase in CCAIMT and total cholesterol and body mass index were identified as the independent predictors of CCAIMT.

Effects of acclimation on cognitive performance in soldiers during exertional heat stress.

This study investigates the effects of exertional heat stress and acclimation status on physiological and cognitive performance. Forty male soldiers performed an exertional heat stress test (EHST) either in a cool (20 degrees C, 16 degrees C wet bulb globe temperature), or in a hot environment (40 degrees C, 29 degrees C wet bulb globe temperature), unacclimatized, or after 10 days of passive or active acclimation. Mean skin and tympanic (Tty) temperatures and heart rates (HR) measured physiological strain. A cognitive test (the computerized Cambridge Neuropsychological Test Automated Batteries attention battery) is administered before and immediately after EHST. EHST in hot conditions induced physiological heat stress (increase in Tty and HR), which caused mild deficits in attention in U group (decreased number of correct responses, and prolonged movement time). Acclimated (passive and active) soldiers suffered no detrimental effects of exertional heat stress, despite almost the same degree of heat strain, measured by Tty and HR.

Physiological tolerance to uncompensated heat stress in soldiers: effects of various types of body cooling systems.

BACKGROUND/AIM: In military services, emergency situations when soldiers are exposed to a combination of nuclear, biological and chemical (NBC) contamination combined with heat stress, are frequent and complex. In these specific conditions, usage of personal body cooling systems may be effective in reducing heat stress. The present study was conducted in order to evaluate the efficiency of four various types of contemporary personal body cooling systems based on the "Phase Change Material" (PCM), and its effects on soldiers' subjective comfort and physiological performance during exertional heat stress in hot environments. METHODS: Ten male soldiers were voluntarily subjected to exertional heat stress tests (EHSTs) consisted of walking on a treadmill (5.5 km/h) in hot conditions (40 degreesC) in climatic chamber, wearing NBC isolating impermeable protective suits. One of the tests was performed without any additional cooling solution (NOCOOL), and four tests were performed while using different types of cooling systems: three in a form of vests and one as underwear. Physiological strain was determined by the mean skin temperature (Tsk), tympanic temperature (Tty), and heart rate values (HR), while sweat rates (SwR) indicated changes in hydration status. RESULTS: In all the cases EHST induced physiological response manifested through increasing Tty, HR and SwR. Compared to NOCOOL tests, when using cooling vests, Tty and Tsk were significantly lower (on 35th min, for 0.44 +/- 0.03 and 0.49 +/- 0.05 degrees C, respectively; p < 0.05), as well as the average SwR (0.17 +/- 0.03 L/m2/h). When using underwear, the values of given parameters were not significantly different compared to NOCOOL tests. CONCLUSIONS: Using a body cooling system based on PCM in the form of vest under NBC protective clothes during physical activity in hot conditions, reduces sweating and alleviates heat stress manifested by increased core and skin temperatures and heart rate values. These effects directly improve heat tolerance, hydration state, decrease in the risk of heat illness, and extends the duration of soldiers' exposure to extreme conditions.

The effects of acclimatization on blood clotting parameters in exertional heat stress.

BACKGROUND/AIM: Exertional heat stress is a common problem in military services. Considering the coagulation abnormalities are of major importance in development of severe heat stroke, we wanted to examine changes in hemostatic parameters in soldiers during exertional heat stress test as well as the effects of a 10-day passive or active acclimatization in a climatic chamber. METHODS: A total of 40 male soldiers with high aerobic capacity performed exertional heat stress test (EHST) either in cool [20 degrees C, 16 degrees C wet bulb globe temperature (WBGT)], or hot (40 degrees C, 29 degrees C, (WBGT) environment, unacclimatized (U) or after 10 days of passive (P) or active (A) acclimatization. Physiological strain was measured by tympanic temperatures (Tty) and heart rates (HR). Platelet count (PC), antithrombin III (AT), and prothrombin time (PT) were assessed in blood samples collected before and immediately after the EHST. RESULT: EHST in hot conditions induced physiological heat stress (increase in Tty and HR), with a significant increase in prothrombin time in the groups U and A. Platelet counts were significantly higher after the EHST compared to the basic levels in all the investigated groups, regardless environmental conditions and acclimatization state. Antithrombin levels were not affected by EHST whatsoever. CONCLUSION: In the trained soldiers, physiological heat stress caused mild changes in some serum parameters of blood clotting such as prothrombin time, while others such as antithrombin levels were not affected. Platelet counts were increased after EHST in all groups. A 10-day passive or active acclimatization in climatic chamber showed no effect on parameters investigated.

[The influence of sepsis as a complication after trauma on immune response to injury].

INTRODUCTION: Mortality rate in trauma complicated with sepsis is exceeding 50%. Outcome is not determined only by infection or trauma, but also by the intensity of immuno-inflammatory response. OBJECTIVE: The aim of this study was to determine the influence of sepsis on the immuno-inflammatory response, in the group of 35 traumatized men, of which in 25 cases trauma was complicated with sepsis. METHODS: Cytokines were measured by ELISA test in plasma. Blood samples were drown on the first, third and fifth day after ICU admission. RESULTS: Proinflammatory cytokine IL-8 was 230-fold higher in trauma + sepsis group (1148.48 vs. 5.05 pg/ml; p < 0.01), and antiinflammatory cytokine IL-ra was 4-fold higher (1138.3 vs. 310.05 pg/ml; p < 0.01), whereas IL-12 and IL-4 showed no significant difference between the groups. CONCLUSION: We concluded that sepsis, as a complication after trauma, drastically enhances immuno-inflammatory response to insult, as indicated by IL-8 and IL-ra, but not IL-12 and IL-4.

[Effect of acclimation on changes in water and electrolyte homeostasis in soldiers during exertional heat stress].

BACKGROUND/AIM: Exertional heat stress is a common problem in military services. The aim of this study was to exemine changes in body water and serum concentrations of some electrolites in soldiers during exertional heat stress (EHST), as well as effects of 10-day passive or active acclimation in a climatic chamber. METHODS: Forty male soldiers with high aerobic capacity, performed EHST either in cool (20 degrees C, 16 degrees C WBGT-wet bulb globe temperature), or hot (40 degrees C, 25 degrees C WBGT) environment, unacclimatized, or after 10 days of passive or active acclimation. The subjects were allowed to drink tap water ad libitum during EHST. Mean skin (Tsk) and tympanic (Tty) temperatures and heart rates (HR) measured physiological strain, while sweat rate (SwR), and serum concentrations of sodium, potassium and osmolality measured changes in water and electrolite status. Blood samples were collected before and immediately after the EHST. RESULTS: Exertional heat stress in hot conditions induced physiological heat stress (increase in Tty, HR, and SwR), with significant decrease in serum sodium concentration (140.6 +/- 1.52 before vs. 138.5 +/- 1.0 mmol/l after EHST, p < 0.01) and osmolality (280.7 +/- 3.8 vs. 277.5 +/- 2.6 mOsm/kg, p < 0.05) in the unacclimatized group. The acclimated soldiers suffered no such effects of exertional heat stress, despite almost the same degree of heat strain, measured by Tty, HR and SwR. CONCLUSION: In the trained soldiers, 10-day passive or active acclimation in a climatic chamber can prevent disturbances in water and electrolitic balance, i.e. decrease in serum sodium concentrations and osmolality induced by exertional heat stress.