Objective To investigate the protective effect of mild hypothermia at different starting times on the physiological functions of the viscera of exertional heat stroke (EHS). Methods A prospective randomized controlled trial was conducted. EHS patients admitted to intensive care unit of the 159th Hospital of People's Liberation Army and the First Affiliated Hospital of Zhengzhou University from June 2015 to June 2017 were enrolled. The patients were divided into 2, 4, 6 hours start hypothermia treatment groups according to the random number table method, the mild hypothermia was initiated at 2, 4 and 6 hours after the disease onset respectively, and the methods were the same in each group. After treatment of 2, 12, 24 hours, the venous blood in the three groups was collected to detect serum cardiac troponin I (cTnI) with chemiluminescence method, MB isoenzyme of creatine kinase (CK-MB) with immunosuppressive method, creatinine (Cr) with creatine oxidase method, β2-microglobulin (β2-MG) with turbidimetry, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) with enzyme method. Multiple organ dysfunction syndrome (MODS) within 24 hours after treatment was recorded. Linear regression analysis of the correlation between mild hypothermia start-up time and MODS was done. Results Ninety-three cases of EHS were included,with 32, 31 and 30 patients in 2, 4, 6 hours start treatment groups respectively. There were no significant differences in gender, age, core temperature, onset time to admission, Glasgow coma scale (GCS), acute physiology and chronic health evaluation system Ⅱ(APACHE Ⅱ) score at admission among the three groups. There were no significant differences in the levels of serum cTnI, CK-MB, Cr, β2-MG, ALT and AST at 2 hours after treatment. But with the prolongation of the treatment time, all indicators gradually increased. And the earlier start of the mild hypothermia, the less significant of the above indexes. All indexes in 2 hours start treatment group were significantly lower than those of 2 hours and 6 hours start treatment groups at 24 hours after treatment [cTnI (ng/L): 49.53±9.25 vs. 56.52±10.05, 64.57±11.21; CK-MB (U/L):51.47±11.83 vs. 57.87±7.43, 64.40±7.93; Cr (μmol/L): 140.97±11.33 vs. 148.16±10.39,155.57±8.65; β2-MG (mg/L): 10.28±1.46 vs. 11.58±2.13, 12.93±1.98; ALT (U/L): 248.53±75.47 vs. 341.42±129.58, 425.77±101.23;AST (U/L): 197.25±42.59 vs. 292.81±58.49, 351.20±60.41, all P < 0.05]. There was significant difference in the incidence of MODS in 2, 4, 6 hours start treatment groups [43.75% (14/32), 64.52% (20/31), 80.08% (24/30), χ2= 8.761, P = 0.013]. Linear regression analysis showed that the earlier onset time of mild hypothermia, the lower incidence of MODS (R2= 0.915, P = 0.013). Conclusion The application of mild hypothermia in 2 hours can effectively protect the physiological function of EHS organs and reduce the incidence of MODS.

Objective To observe the effect of different core temperatures (Tc) after heat strike on serum inflammatory cytokines and multiple organ dysfunction syndrome (MODS) in rat. Methods 120 male Sprague-Dawley (SD) rats were randomly divided into normal control group (n = 30) and heat strike group (n = 90). The rats in heat strike group were put into simulated thermal climate animal module after adaptive training. The module temperature was raised to 39 ℃ in 30 minutes with 65% humidity. The rats ran simultaneously at 15 m/min, on the slope of 0°, 8 minutes each time, 2 minutes interval, and the heat strike time was 90 minutes. After the rats came out of the module, rectal temperature, which was Tc value, was recorded. The rats died or Tc < 41 ℃ during the experiment were excluded, the remaining 73 rats were divided into three subgroups: 41.0-41.9 ℃ (n = 38), 42.0-42.9 ℃ (n = 26), and ≥43.0 ℃ (n = 9). The rats in the normal control group were reared at temperature of (25±2) ℃, and humidity of (55±5)%. At 0 hour and 24 hours after the rats came out of the module, femoral artery blood was collected to determine serum interleukins (IL-1α, IL-1β, IL-17), tumor necrosis factor-α(TNF-α) andγ-interferon (IFN-γ) by enzyme-linked immunosorbent assay (ELISA). The cardiac troponin I (cTnI), MB isoenzyme of creatine kinase (CK-MB), serum creatinine (SCr), blood urea nitrogen (BUN), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels were determined by automatic biochemical analyzer. The incidence of MODS and the number of accumulative organs within 24 hours of the rats in different Tc of heat strike group were compared and analyzed. Results The serum inflammatory cytokines and biochemical parameters at 0 hour after heat strike were significant higher than those of the normal control group, and showed a time dependence. Further analysis showed that the inflammatory response and organ dysfunction in rats were increased gradually with the increase in Tc of rats. Compared with the normal control group, at 24 hours after heat strike, inflammatory cytokines in Tc≥43.0 ℃ rats were increased obviously [IL-1α (ng/L): 13.56±2.07 vs. 2.24±0.62, IL-1β (ng/L): 17.11±1.90 vs. 7.40±1.52, IL-17 (ng/L): 17.00±1.41 vs. 6.00±1.78, TNF-α (ng/L):16.78±1.79 vs. 7.27±1.74, IFN-γ (ng/L): 21.11±2.09 vs. 10.43±2.31], and the biochemical parameters were also increased obviously [cTnI (ng/L): 50.78±6.67 vs. 20.53±3.09, CK-MB (U/L): 62.89±3.82 vs. 22.00±3.01, SCr (μmol/L): 149.22±4.35 vs. 92.53±8.32, BUN (nmol/L): 55.22±1.99 vs. 19.10±2.02, ALT (U/L): 388.33±4.97 vs. 100.23±10.61, AST (U/L): 361.22±6.53 vs. 97.67±10.54, all P < 0.01]. The incidence of MODS within 24 hours in the heat strike group was 54.79% (40/73), and the higher the Tc, the higher the incidence of MODS, and the more insulted organs [the incidence of MODS in 41.0-41.9 ℃, 42.0-42.9 ℃, and ≥43.0 ℃ subgroups was 36.84% (14/38), 65.38% (17/26), 100.00% (9/9), and the organ involvement rate was 12.17% (37/304), 23.08% (48/208), and 48.61% (35/72), respectively, when 8 organs or systems were calculated for each rat, both P < 0.01]. Conclusion The higher the Tc of heat strike rats, the stronger the inflammatory reaction and the more serious the damage of tissue, and the more extensive damage of the organs.

Objective To investigate the effects of heat acclimatization training on the inflammatory reaction and multiple organ dysfunction syndrome (MODS) in patients with exertional heat stroke (EHS). Methods 600 officers and soldiers from a special team who participated in 5 km armed wild training from June to July 2017 were selected as the research object, while 30 healthy officers and men who did not participate in armed wild training during the same period were selected as normal controls. The officers and soldiers who participated in 5 km armed wild training (ambient temperature > 35 ℃, humidity > 65%, 2-3 times a week for 3 weeks) were divided into heat acclimatization group and non-acclimatization group, with 300 in each group. The heat acclimatization group first took part in the heat acclimatization training of wild or long distance running (the initial temperature was 30 ℃, gradually transferred to the hot time of 37 ℃), 2 hours each time, twice a day, and 5 days a week, for a total of 2 weeks. Venous blood was taken before and after heat acclimatization training, before armed wild training, and after the last training or EHS onset, and the contents of serum interleukin (IL-1β, IL-10), tumor necrosis factor-α (TNF-α) and γ-interferon (IFN-γ) were detected by enzyme linked immunosorbent assay (ELISA). The occurrence of EHS and MODS in EHS patients were recorded. Results There was no significant difference in serum inflammatory factors between the officers and soldiers who participated in the training and the healthy control group before heat training or cross-country training. Compared with those before heat training, IL-1β, TNF-α, IFN-γ were significantly increased in all participants of heat acclimatization training while IL-10 was significantly decreased. For those who experienced premonitory (6 cases) and mild (2 cases) heatstroke during training, they could return to normal without severe heatstroke or EHS within 10-30 minutes after being immediately put in a cool and ventilated place and given anti- heatstroke drugs and other interventions. Compared with those before wild training, the levels of inflammatory factors in the two groups of officers and soldiers also changed after wild training, but the increase or decrease of inflammatory indexes in the heat acclimatization group were significantly smaller than those in the non-acclimatization group [IL-1β (ng/L): 10.65±5.18 vs. 12.13±7.91, TNF-α (ng/L): 14.60±5.79 vs. 16.27±8.52, IFN-γ (ng/L): 13.66±5.43 vs. 15.33±8.71, IL-10 (ng/L):8.22±2.68 vs. 7.13±2.63, all P < 0.05]. During armed wild training, a total of 27 cases of EHS occurred. The incidence of EHS in the heat acclimatization group was significantly lower than that in the non-acclimatization group [2.67% (8/300) vs. 6.33% (19/300), χ2= 4.693, P = 0.030]. In patients with EHS, IL-1β, TNF-α, IFN-γ after wild training in the heat acclimatization group were also significantly lower than those in the non-acclimatization group, and IL-10 was significantly higher [IL-1β (ng/L): 34.50±3.74 vs. 39.53±4.51, TNF-α (ng/L): 43.75±2.87 vs. 46.79±2.66, IFN-γ (ng/L): 40.25±1.75 vs. 46.58±1.92, IL-10 (ng/L): 7.50±2.45 vs. 5.42±1.80, all P < 0.01], and the incidence of MODS and organ involvement of EHS patients in the heat acclimation group were significantly lower than that in the non-acclimatization group [50.00% (4/8) vs. 89.47% (17/19), χ2= 5.075, P = 0.024; 28.13% (9/32) vs. 47.79% (65/136), χ2=4.066, P=0.044]. Conclusion Heat acclimatization training before high strength training in high temperature and humidity environment can effectively reduce the degree of inflammation reaction of EHS, protect the physiological functions of EHS organs, and reduce the incidence of MODS.

Objective To observe the relationship between different degree of cerebral edema and multiple organ dysfunction syndrome (MODS) of exertional heat stroke (EHS) patients. Methods The patients with EHS admitted to intensive care unit (ICU) of the 159th Hospital of PLA from June 2015 to June 2017 were enrolled. The electrical impedance perturbation coefficient (EIDC) of bilateral cerebral hemispheres were monitored at 2, 24 and 72 hours after the onset of the disease by BORN-BE non-invasive dynamic cerebral edema monitor, and the patients were divided into 9+ group, 10+ group and 11+ group according to the resistance of the measured mean impedance coefficients. Fasting venous blood of the patients were acquired after 2 hours and 72 hours of the disease, the levels of serum interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), nitric oxide (NO), nitric oxide synthase (NOS), cardiac troponin I (cTnI), MB isoenzyme of creatine kinase (CK-MB), creatinine (Cr), β2-microglobulin (β2-MG), alanine aminotransferase (ALT) and aspartate transaminase (AST) were detected. The occurrence of MODS within 72 hours was recorded. Linear regression analysis of the correlation between EIDC and MODS was done. Results All 124 EHS patients were male; the age was (22.10±4.43) years. Among them, 20 in EIDC 9+ group, 61 in 10+ group, and 43 in 11+ group. There were no significant differences in the levels of IL-1β, TNF-α, NO, NOS, cTnI, CK-MB, Cr, β2-MG, ALT, AST after onset of 2 hours among different EPIC groups; all the indexes of 72 hours were significantly higher than those of 2 hours in each group; and the higher the EIDC, the more obvious increase of each index [EIDC 9+ group, 10+ group, 11+ group at 72 hours IL-1β (ng/L): 12.05±3.75, 18.49±7.94, 23.21±10.44;TNF-α (ng/L): 13.10±3.18, 18.92±7.23, 23.40±10.17; NO (μmol/L): 99.50±12.10, 111.41±17.75, 120.81±15.58;NOS (kU/L): 47.95±8.33, 56.70±12.12, 63.37±12.60; cTnI (ng/L): 92.75±20.92, 107.20±18.96, 117.30±14.53;CK-MB (U/L): 73.55±9.25, 83.23±13.19, 93.49±12.25; Cr (μmol/L): 165.30±9.41, 176.62±9.83, 180.09±10.14;β2-MG (mg/L): 16.45±2.68, 19.07±3.68, 22.05±3.93; ALT (U/L): 500.10±87.05, 563.90±91.28, 612.16±90.61, AST (U/L): 414.30±53.35, 470.51±73.83, 512.09±81.29, respectively, two-two comparison all P ＜ 0.05], the higher of the MODS incidence [40.00 % (8/20), 65.57% (40/61), 83.72% (36/43), x2= 12.199, P = 0.002]. Linear regression analysis showed that the degree of cerebral edema was positively correlated with the incidence of MODS (R2= 0.905, P = 0.002). Conclusion The higher of the EIDC, the more severe of cerebral edema, the stronger of the inflammatory reaction, and the more severe damage of heart, liver, kidney and other organs in EHS patients within 72 hours.

OBJECTIVE: To explore the relationship between physiological parameters changes and severe heatstroke induced by 5-km armed cross-country training. METHODS: A total of 521 male officers and soldiers from a special team who participated in the summer training of 5-km armed cross-country training from year 2016 to 2017 were enrolled. All trainees participated in 5-km armed cross-country training in high temperature and humidity environment of ambient temperature > 32 centigradeand (or) relative humidity > 65%. The trainees were divided into two groups according to the incidence of severe heatstroke in the course of training. The age, enlistment time, constitution score, body mass index (BMI), external environment (ambient temperature, relative humidity, wind speed, heat index) of trainees of the two groups, and the change rates of arterial blood oxygen saturation (SaO₂), body temperature, pulse and blood pressure within 5 minutes after the 5-km armed cross-country training were compared between the two groups. The risk factors of severe heatstroke were screened by two classified Logistic regression analysis, and the predictive value of various risk factors of severe heatstroke was analyzed by the receiver operator characteristic curve (ROC). RESULTS: In 521 trainees of 5-km armed cross-country training, 29 trainees suffered from severe heatstroke accounting for 5.57%. There was no significant difference in the age, enlistment time, constitution score, BMI, or external environment during 5-km armed cross-country training between severe heatstroke group and non-severe heatstroke group. Compared with those without severe heatstroke, the descending rates of body temperature, pulse, blood pressure and SaO₂ increased rate within 5 minutes after 5-km armed cross-country training of severe heatstroke trainees were significantly decreased [temperature descending rate: (0.67±0.30)% vs. (1.43±1.28)%, pulse descending rate: (7.53±5.21)% vs. (13.48±8.07)%, blood pressure descending rate: (9.28±6.84)% vs. (19.42±7.73)%, SaO₂ increased rate: (0.51±0.39)% vs. (1.50±1.43)%, all P < 0.01]. Two classification Logistic regression analysis showed that the temperature descending rate [odds ratio (OR) = 0.485, 95% confidence interval (95%CI) = 0.289-0.817], pulse descending rate (OR = 0.903, 95%CI = 0.845-0.965), blood pressure descending rate (OR = 0.841, 95%CI = 0.790-0.896), and SaO2 increased rate (OR = 0.421, 95%CI = 0.250-0.711) were the risk factors for severe heatstroke during 5-km armed cross-country training (all P < 0.01). ROC curve analysis showed that temperature descending rate [area under ROC curve (AUC) = 0.659, 95%CI = 0.604-0.714], pulse descending rate (AUC = 0.730, 95%CI = 0.762-0.900), blood pressure descending rate (AUC = 0.831, 95%CI = 0.659-0.801), SaO₂ increased rate (AUC = 0.711, 95%CI = 0.655-0.767) could be used for the incidence of severe heatstroke prediction during 5-km armed cross-country training (all P < 0.01), and the predicted value was the same. CONCLUSIONS Under the same conditions, the severe heatstroke during 5-km cross-country training is closely related to the descending rates of body temperature, pulse, and blood pressure as well as SaO₂ increased rate within 5 minutes after the training, whose predictive values for severe heatstroke were the same.
Blood Pressure ; Heart Rate ; Heat Stroke ; Hot Temperature ; Humans ; Male ; Risk Factors

Objective: To explore the relationship between physiological parameters changes and severe heatstroke induced by 5-km armed cross-country training. Methods: A total of 521 male officers and soldiers from a special team who participated in the summer training of 5-km armed cross-country training from year 2016 to 2017 were enrolled. All trainees participated in 5-km armed cross-country training in high temperature and humidity environment of ambient temperature > 32 ℃and (or) relative humidity > 65%. The trainees were divided into two groups according to the incidence of severe heatstroke in the course of training. The age, enlistment time, constitution score, body mass index (BMI), external environment (ambient temperature, relative humidity, wind speed, heat index) of trainees of the two groups, and the change rates of arterial blood oxygen saturation (SaO₂), body temperature, pulse and blood pressure within 5 minutes after the 5-km armed cross-country training were compared between the two groups. The risk factors of severe heatstroke were screened by two classified Logistic regression analysis, and the predictive value of various risk factors of severe heatstroke was analyzed by the receiver operator characteristic curve (ROC). Results: In 521 trainees of 5-km armed cross-country training, 29 trainees suffered from severe heatstroke accounting for 5.57%. There was no significant difference in the age, enlistment time, constitution score, BMI, or external environment during 5-km armed cross-country training between severe heatstroke group and non-severe heatstroke group. Compared with those without severe heatstroke, the descending rates of body temperature, pulse, blood pressure and SaO₂ increased rate within 5 minutes after 5-km armed cross-country training of severe heatstroke trainees were significantly decreased [temperature descending rate: (0.67±0.30)% vs. (1.43±1.28)%, pulse descending rate: (7.53±5.21)% vs. (13.48±8.07)%, blood pressure descending rate: (9.28±6.84)% vs. (19.42±7.73)%, SaO₂ increased rate: (0.51±0.39)% vs. (1.50±1.43)%, all P < 0.01]. Two classification Logistic regression analysis showed that the temperature descending rate [odds ratio (OR) = 0.485, 95% confidence interval (95%CI) = 0.289-0.817], pulse descending rate (OR = 0.903, 95%CI = 0.845-0.965), blood pressure descending rate (OR = 0.841, 95%CI = 0.790-0.896), and SaO₂ increased rate (OR = 0.421, 95%CI = 0.250-0.711) were the risk factors for severe heatstroke during 5-km armed cross-country training (all P < 0.01). ROC curve analysis showed that temperature descending rate [area under ROC curve (AUC) = 0.659, 95%CI = 0.604-0.714], pulse descending rate (AUC = 0.730, 95%CI = 0.762-0.900), blood pressure descending rate (AUC = 0.831, 95%CI = 0.659-0.801), SaO₂ increased rate (AUC = 0.711, 95%CI = 0.655-0.767) could be used for the incidence of severe heatstroke prediction during 5-km armed cross-country training (all P < 0.01), and the predicted value was the same. Conclusions Under the same conditions, the severe heatstroke during 5-km cross-country training is closely related to the descending rates of body temperature, pulse, and blood pressure as well as SaO₂ increased rate within 5 minutes after the training, whose predictive values for severe heatstroke were the same.