RESUMO
ObjectiveTo investigate the changes in characteristics of blood gas analysis of heatstroke rats residing in dry-heat environment of desert, and to provide a theoretical reference for its treatment in clinic.Methods Forty-eight male Sprague-Dawley (SD) adult rats under anesthesia were divided into six groups by random number table, with 8 rats in each group: namely mild, moderate, severe heatstroke groups and their corresponding control groups. The rats were placed in an artificial chamber with simulated desert dry-heat environment (temperature 41℃, humidity 10%) for about 70, 110, 145 minutes, respectively, to reproduce mild, moderate, severe heatstroke models. The rats in control groups were placed in a normothermic environment for corresponding duration. Abdominal aorta blood of each group was collected for blood gas analysis, and electrolytes were determined by a portable blood gas analyzer.Results① Arterial partial pressure of carbon dioxide (PaCO2) in mild heatstroke group was increased to (45.64±8.19) mmHg (1 mmHg = 0.133 kPa), arterial oxygen saturation (SaO2) was decreased to 0.84±0.08, pH value was lowered to 7.36±0.11, showing that respiratory acid-base imbalance was resulted. Base excess of extracellular fluid (BEecf) in moderate heatstroke group was decreased to (-3.00±0.76) mmol/L, HCO3- was decreased to (19.39±1.89) mmol/L, and pH value was lowered to 7.21±0.07, indicating that metabolic acid-base imbalance was aggravated gradually. The changes in parameters in severe heatstroke group gradually became more serious, and a significant difference was found as compared with those of mild and moderate heatstroke groups (PaCO2:F = 6.537,P = 0.006; SaO2:F = 5.174,P = 0.015; pH value:F = 10.736,P = 0.001;BEecf:F = 67.136,P = 0.000; HCO3-:F = 5.612,P = 0.011), manifesting an obvious combination of respiratory acidosis and metabolic acidosis, and a serious mixed acid-base disturbance was produced.② Compared with corresponding control groups, hemoglobin (Hb) was significantly increased in moderate heatstroke group (g/L: 15.31±1.84 vs. 13.28±0.94,t = 2.791,P = 0.014), Hb and hematocrit (HCT) in severe heatstroke group were significantly increased [Hb (g/L): 16.59±2.52 vs. 13.42±1.15,t = 3.224,P = 0.006; HCT: (53.50±6.63)% vs. (45.50±4.47)%,t = 2.828, P = 0.013], showing that the degree of dehydration was aggravated gradually from mild to serious degree.③ Serum sodium content in mild heatstroke group was normal (t = 0.665,P = 0.517), serum potassium content was lowered significantly (t = -2.526,P = 0.024); serum sodium content in moderate heatstroke group was increased significantly (t = 2.162,P = 0.048), serum potassium content was lowered significantly (t = -5.458,P = 0.000); and serum sodium content in severe heatstroke group rose obviously (U = 12.500,P = 0.038), and most of the rats showed hypokalemia, with a small proportion of rats showed obvious hyperkalemia (U = 19.500,P = 0.195).ConclusionsAcidosis, electrolyte disturbance, respiratory failure and dehydration in heatstroke occurred in dry-heat environment of desert. It indicates that resuscitation should focus on correction of respiratory acidosis, with simultaneous correction of metabolic acidosis, and one should be alert to correct dehydration and electrolyte disturbance. During the moderate phase and the serious phase, correction of aggravated metabolic acidosis should be reinforced, and the prevention and treatment of the severe dehydration and electrolyte disturbance should be undertaken actively.
RESUMO
Objective To observe the function of kidney compromised and histopathological changes of renal tissue in heatstroke rats under the dry-heat atmosphere of desert in order to find the mechanism for provide a rationale of clinical treatment.Methods Forty-eight anaesthetized rats were divided into six groups (n =8 in each group):mild heatstroke group with its control group,moderate heatstroke group with its control group,and severe heatstroke group with its control group.The rats of three heatstroke groups were placed in a dry-heat environment prolonged with 41 ℃ and 10％ humidity,and the three control groups were placed in a room temperature prolonged with 25 ℃ and 35％ humidity.At heatstroke status of each group,arterial blood samples were collected from each group for testing creatine kinase (CK),creatinine (CREAT),uric acid (UA) and urea,kidney tissues and muscle tissues were taken for pathological examinations.Results Pathological examination showed dilatation and congestion of vessels,thrombosis,bleeding,protein casts and endothelium injury were found in the heatstroke rats.In mild heatstroke,the pathological changes mainly manifested as dilatation and congestion of vessels ; in moderate one,the changes mainly manifested as thrombosis; and in severe one,changes mainly manifested as bleeding and protein casts.Muscle tissues presented rhabdomyolysis,especially in severe one.The differences in biomarkers between three different degrees of heatstroke showed statistical significance (CK:F =136.204,P =0.000;CREAT:F =172.865,P=0.000; UA:F=546.454,P=0.000; urea:F=73.823,P=0.000).There was no significant difference in UA between mild heatstroke group and its control group (t =1.943 ;P =0.072),and the differences in rest biomarkers showed statistical significance between each heatstroke group and its control group (P =0.000).Conclusions The kidney injury developed during heatstroke in dry-heat environment of desert suggests that we should be alert to disseminated intravascular coagulation (DIC),myolysis and acute kidney failure,and should monitor the blood biochemical changes closely and treat it energetically,rescuing a heatstroke patient in dry-heat environment of desert.