The Rational Approach Of Block Treatment With Chymotrypsin Injection For Chinese Cobra Bites

Background:Hundreds of thousands of people were bitten by the snakes in China every year. Though the mortality rates had declined obviously with the benefits of today’s medical technology, the prevalence of disability remains at a higher level after snake bites, especially after the bites of Chinese cobra. The Chinese cobra was a common snake species of the southern provinces in our country, and it’s venom was mixed but contain cytotoxin as the main ingredient, with which could result in serious damage to the skin and soft tissue besides death from multiple organ dysfunction syndrome, and sometimes end in a affected limb cut off. Promoting detoxification and halting the spread of snake venom were the most important measure in pre-hospital emergency. Block treatment with chymotrypsin after snake bites was widely used in clinic. But its rationality still was controversial.Objective:To approach the rationality of block treatment with chymotrypsin for Chinese cobra bites.Methods:Experiment in vitro with biuret reaction:mixed Chinese cobra venom (20mg) with different concentrations of chymotrypsin, and used biuret reaction to measure the remnant venom by directrix curve of cobra venom-biuret reaction after reaction completely. Rats were randomly divided into 10 groups with 10 Rats in each, which were injected in the ventral midline respectively. According to the different injection ways, experimental rats were divided into the following groups:blank control group(group A):only injection water; toxic model group (group B):Chinese cobra venom; group C:block treatment with injection water; group D/E:30min/60min after block treatment with chymotrypsin; group F/G:mixed chymotrypsin 1.0U/2.1U with Chinese cobra venom 0.0072mg and injected after half an hour for reaction; group H/I/J: chymotrypsin concentration respectively for the 21U/ml,40U/ml,400U/ml and 0.1ml for each injection. The area of subcutaneous hemorrhage were recorded and analyzed. Besides 100 rats were randomly divided into experimental group and control group, the mortality comparison was carried on between the experimental group (block treatment) and the control group (Chinese cobra venom injection).Results:1.Experiment in vitro:all reactions were completed within 30 minutes after Chinese cobra venom (20mg) mixed with chymotrypsin 200-4000U, the absorbance after reaction was different related to the dose of chymotrypsin.2. Animal experiment:the subcutaneous hemorrhage of group B was much more serious than group A. The subcutaneous hemorrhage areas of group D and E were respectively 3.05±0.12cm2 and 3.38±0.10cm2 after 30min and 60min of block treatment, both of them were smaller than 4.04±0.12 cm2 of group C (p<0.05 for both), an abnormal hemorrhage came up in the injection site of chymotrypsin compared group E to group D. The 1.77±0.13 cm2 of subcutaneous hemorrhage area in group F was bigger than 0.81±0.10 cm2 in group G, but the magnitude of hemorrhages was less, Comparative differences between groups were statistically significant (P<0.05 for both). The area of group H, group I and group J respectively was 0.29±0.04 cm2,0.64±0.07 cm2 and 1.23±0.14 cm2; Comparative differences was statistically significant (P< 0.05), and subcutaneous hemorrhage showed a positive correlation associated with the concentration of chymotrypsin (R=0.966, P<0.05). The mortality in the block treatment group and control group respectively were 44.0% and 52.0%, but the difference showed no statistical significance (P>0.05).Conclusions:1.Few Chinese cobra venom could be hydrolyzed in vitro. The Chinese cobra venom can inhibit or hydrolyze chymotrypsin, and hydrolytic ability is rely on a dose of chymotrypsin.2. Chymotrypsin can hydrolyze un-denatured protein and damage the normal tissue. Block treatment with chymotrypsin can increase the risk of subcutaneous hemorrhage after Chinese cobra bites for the coordination effect with venom.3.The dosage of chymotrypsin that was recommended by clinic in block treatment after Chinese cobra bites did not reach the mark of inactivating the Chinese cobra venom, furthermore increased the risk of subcutaneous hemorrhage; clinical continues using is not recommended.