Scoring methods in injury assessment of rats with trauma combined with seawater immersion / 中华创伤杂志

ABSTRACT

Objective:To explore and establish the scoring method of injury assessment in rats with trauma combined with seawater immersion, so as to provide a reference for injury assessment in the special environment of trauma combined with seawater immersion.Methods:Sixty-four SD rats were divided into two groups according to the random number table, including hemorrhagic shock group and compound injury group, with 32 rats per group. Each group was divided into trauma combined with seawater immersion group and simple trauma group, with 16 rats per group. In trauma combined with seawater immersion group, the hemorrhagic shock model was placed in 15℃ seawater for 1 hour to start bleeding, and the blood loss was 30% of the total blood volume. The composite injury model caused 10% Ⅱ degree burns and was incised along the vental midline with a length of about 2 cm, and then placed in 15℃ seawater for 1 hour. The death and survival time were recorded.The survival time significantly longer than 4 hours out of water was recorded as survival, and significantly shorter than 4 hours out of water was recorded as death. Data were observed within 9 hours after injury, including the changes of physiological indexes (respiration, blood pressure, anal temperature) and arterial blood gas (blood glucose, pH value, blood lactic acid, arterial oxygen partial pressure, arterial carbon dioxide partial pressure, bicarbate, sodium ion, chloride ion, calcium ion, potassium ion). Each index were compared between trauma combined with seawater immersion group and simple trauma group. According to the survival situation of all the trauma combined with seawater immersion group at 4 hours out of water, the rats were divided into survival group and death group. The indicators affecting survival were screened, and then the scatter plot of each index corresponding to the mortality rate was established. According to the trend of each index in different interval in the scatter chart, the score table of injury condition was established.Results:The total mortality was 28% (9/32) in trauma combined with seawater immersion group, and was 6% (2/32) in simple trauma group ( P<0.05). The survival time in trauma combined with seawater immersion group [(8.1±3.7)hours] was shorter than that in simple trauma group [(11.3±4.8)hours] ( P<0.05). In trauma combined with seawater immersion group, the respiratory rate[(58.8±2.9)times/min] was slower than that in simple trauma group [(100.4±7.2)times/min], blood pressure [(80.0±25.1)mmHg] was lower than that in simple trauma group [(89.8±18.1)mmHg], and anal temperature [22.4(20.1, 25.0)℃] was significantly lower than that in sample trauma group [31.7(30.5, 33.2)℃], pH value (7.1±0.1) was lower than that in simple trauma group (7.3±0.1), and arterial oxygen partial pressure [(196.3±34.1)mmHg], arterial carbon dioxide partial pressure [45.5(35.1, 51.1)mmHg], serum sodium [145(142, 148)mmol/L], serum chlorine [120(115, 125)mmol/L], serum calcium [(1.3±0.1)mmol/L]as well as serum potassium [(3.6±0.8)mmol/L] were higher than those in simple trauma group [(149.4±22.6)mmHg, 29.7(25.6, 34.5)mmHg, 142(139, 144)mmol/L, 118(114, 121)mmol/L, (1.2±0.1)mmol/L, (3.3±0.6)mmol/L] (all P<0.05). There were no significances in other indexes between the two groups ( P>0.05). In death group, the breathing[36(30, 36)times/min], blood pressure [(43.1±21.8)mmHg], anal temperature [(20.0±1.9)℃], pH value (7.1±0.1), and bicarbonate [(12.3±2.2)mmol/L] were significantly inhibited or suppressed compared with survival group [60(48, 78)times/min, (86.6±19.3)mmHg, (23.0±3.1)℃, 7.2±0.1, (14.6±2.3)mmol/L (all P<0.05). While the two groups showed no significant differences in other indices ( P>0.05). Therefore, the respiration, blood pressure, rectal temperature, pH value and bicarbonate that significantly affect the survival of rats were screened. According to the death rate corresponding to different intervals, a score value was assigned to the interval as the weight of its impact on survival, namely on the severity of the injury, and an injury score table for trauma combined with seawater immersion in rats was established. The injury scoring scale <6 points indicated no death, 6-9 points indicated the mortality of 50%, ≥9 points indicated the mortality of 71%. The 6 points and 9 points were cutoff value of the scale. It can be considered that the scale of <6 points was classified as minor injury, 6-9 points as moderate injury, and ≥9 points as severe injury. Conclusions:The seawater immersion can result in reduced survival time and increased early mortality, manifested as respiratory depression, more serious blood loss, severe hypothermia, severe metabolic acidosis, water and electrolyte disorders (high sodium, high chlorine, high calcium, and high potassium), etc. According to the respiration, blood pressure, anal temperature, pH value and bicarbate, which affect the survival of rats, the injury rating scale of rats with trauma combined with seawater immersion can be established by using the scatter chart. The predicted mortality rate by using the rating scale was roughly consistent with the actual mortality rate, so the injury rating scale basically had a good prediction and hint for the trauma rats combined with seawater immersion.