The routine admission history and physical examination should provide and record, if possible, the identity and length of the snake, the time of the bite, and the details of all first aid measures employed, including the time lapse for each and the mode of transportation to the hospital. The record should state whether a tourniquet, incision and suction, or the ligature-cryotherapy technique has or has not been used. Inquiry should be made concerning previous bites, allergic manifestations in general, and whether or not the patient had previously received horse serum. The admission examination should provide information from which the severity of the envenomation can be estimated as a guide to the need for the administration of antivenin and other therapy. Sensitivity tests should be instituted promptly during admission if not previously begun.
When the patient enters the hospital, blood should be drawn immediately for typing, matching and coagulation studies.
Although envenomation by one of the snakes of North America may present severe signs and symptoms, death is rare except in children or following envenomation by a large snake. However, permanent damage of an involved extremity is frequent following a bite by certain of the North American venomous snakes; plastic or orthopedic surgical repair to restore function, or amputation, are not unusual consequences. Early and continuing close observation is needed to determine if certain therapeutic measures prevent or promote undesirable results.
Laboratory Tests
No rigid set of rules regarding therapy can be justified; the responsible physician must use his best judgment in his choice of tests to be performed as a guide to procedures to be used.
Clinical studies could include items such as repeated hematologic tests, hepatic and renal function studies, serial electrocardiograms, electroencephalograms, and other studies to therapy, depending on the composition of the venom involved and within the limits of personnel, time and equipment available.
Therapeutic Procedures
A. Systemic
1. Immobilization. During transportation, admission procedures, and most of the early hospitalization period, immobilization of the affected part and absolute rest should be continued. A sedative or analgesic may be administered to relieve restlessness and anxiety; ice bags may be applied to alleviate severe pain. The extremity should be immobilized in the position of function, and active and passive exercises to prevent contracture started after the third day if consistent with the patient’s condition.
2. Blood Transfusion. Postmortem examinations have at times revealed extensive retroperitonial and intraperitonial hemorrhage, and hemorrhage into the viscera, including the liver and kidney. Progressive decrease in the total volume of circulating red blood cells has been attributed to the development of a massive hemolytic anemia or internal hemorrhage. Blood transfusions may be necessary and at times have been followed by marked improvement. Studies of the several factors involved in blood clotting may be useful as guides to treatment. The first and subsequent specimens of urine should be especially examined for the presence of red blood cells, hemoglobin, and protein.
3. Electrolyte Balance. Abnormality of fluid and electrolyte balance should be detected and corrected on a continuing basis.
4. Antivenin. Polyvalent or specific antivenins prepared from venoms of snakes in the same geographic area should be administered in therapeutic quantity as recommended by the manufacturer only with full realization that the hazard of immediate allergic reaction or delayed serum sickness are factors to be evaluated in the decision to carry out this type of treatment. During hospitalization, antivenin should be given intravenously, provided that sensitivity tests indicate that the patient is not allergic to the antiserum to be used. Desensitization, if necessary, should precede the administration of antivenin by any route. The use of antivenin in such cases should be carefully evaluated. Injection in normal muscles in other extremities would be the second choice, since local injections into the deposit site do not diffuse efficiently into the entire damaged area and would increase the hazard of pressure ischemia leading to increased tissue necrosis. Epinephrine should be available for immediate use when foreign protein is being administered.
5. Corticosteroids. The use of corticosteroids should be restricted to the prevention or treatment of late manifestations of allergy following administration of antivenins.
6. Antibiotics. A broad-spectrum antibiotic should be administered promptly in appropriate dosage if the reaction to envenomation is severe. Since the nature of the injury markedly predisposes to infection, and pathogenic bacteria are found in the wound, this use of antibiotics seems justified. Laboratory sensitivity tests, if available, should control the continuing choice of antibiotics to be used. A massive wound infection with severe systemic reaction could be mistaken for severe envenomation. Repeated blood and wound cultures would be of help in making the distinction.
7. Tetanus Prophylaxis. Tetanus toxoid should be administered upon admission if it has not been given as a first aid measure.
8. Respiratory Paralysis. If respiratory paralysis develops following envenomation by one of the Elapidae (this family includes the coral snake), the use of tracheostomy and intermittent positive pressure artificial respiration is indicated.
9. Renal Shutdown has been an occasional occurrence following massive envenomation. An awareness of this possible complication can do much toward the prevention and treatment of secondary effects arising after its occurrence. Routine daily tests such as B.U.N., CO₂ combining power, and serum potassium levels are indicated in severe cases.