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necessary. A comparison of the reported fatality rates due to snake bites in Sri Lanka indicates a significant reduction in mortality in the recent past 2,3,4. The easy availability of antivenom serum in Government Hospitals and facilities for intensive care management may have contributed to the reduction in mortality 5,6,7. Furthermore, early hospital admission due to greater awareness of the public of the availability of effective treatment may also have been an important contributory factor in reducing mortality rates. The efficacy of AVS treatment in snake envenoming is widely accepted 4,5. The AVS available in Sri Lanka are polyvalent equine sera manufactured in Haffkine Laboratories and the serum institute of India. However, adverse reaction to AVS are common. These reactions vary in severity from mild pyrogenic reaction to severe anaphylaxis 6. This has led to a reluctance to use of AVS specially among doctors practicing in peripheral hospitals. There are several reports describing the adverse reactions of AVS but not many address the advantages of AVS. Further, irrational use of AVS also been reported. These include the use of AVS in bites of hump nosed viper, and in bites of cobra, common krait, and Russell’s viper in the absence of systemic envenoming 7. Considering the advantages that AVS can offer in the treatment of snake bite envenoming, a concerted effort should be made to encourage rational practice in the treatment of snake bite. The aims of this prospective study were to investigate the effectiveness and document the adverse reactions to AVS administration in hospital practice in Sri Lanka.
Methodology This study was conducted in the General Hospital, Anuradhapura. The study commenced in September 1998.All patients admitted to the unit A, of General Hospital, Anuradhapura with a history of snake bite were observed closely. Out |
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of these, 60 consecutive cases, who
were treated with AVS were carefully observed, and examined whenever
necessary. Any reaction following treatment with AVS was immediately
recorded in a pre designed observation form, categorizing reactions
into two groups, minor and major based on certain criteria. Minor criteria
were rigor, fever, sweating, itching, urticaria, abdominal pain, cough,
rhonchi, and increased body temperature. Major criteria were dyspnoea,
cold clammy skin, central cyanosis, tachycardia, low volume pulse, and
hypotension. The reactions were grouped as mild, moderate and severe
based on the above criteria. Development of cold clammy skin with any
combination of reactions were considered a severe reaction, combination
of less than six minor criteria was considered mild reaction and combination
of minor criteria plus any major criterion other than hypotension and
cold clammy skin was considered a moderate reaction. Other data recorded
included age gender, previous history of significant medical illness,
history of eczema, catarrh, and urticaria and food and drug allergy.
The offending snakes were identified either by studying characteristics
of the dead snake if it was produced, or by showing specimens of snakes.
If both failed, clinical features were used in identifying the type
of snake. Accordingly the bites were grouped as Russell’s viper
bites, common krait bites or cobra bites. The time of the initial reaction
and the time period of reaction after the administration of AVS was
also recorded. However, routine method of management of the snake bites
was adopted in the unit. The routine way of the management of snake
bites in the unit was to administer a standard dose of 10 vials of AVS
when indicated after a snake bite and this dose was doubled in severe
cases. With the onset of adverse reaction to AVS, hydrocortisone 400mg
and chlopheniramine 10mg by intravenous bolus injections were administered
while continuing the AVS infusion. If the reactions were complicated
with vomiting, metochlopramide 10mg (IV bolus) were given. In the case
of continuing severe reactions, intravenous hydrocortisone 1000mgs was
infused over one hour. Severe anaphylactic reactions were managed with
subcutaneous adrenaline in addition to the above.
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