Envenomation of Snake Bites

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How to treat a patient with a snake bite(Australian Version)

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Envenomation of Snake Bites

  1. 1. ENVENOMATION ELS Course
  2. 2. OBJECTIVES <ul><li>Case presentation </li></ul><ul><li>Initial stabilisation </li></ul><ul><li>Specific treatment </li></ul><ul><ul><li>uses and misuses of VDK </li></ul></ul><ul><ul><li>uses and misuses of antivenom </li></ul></ul>
  3. 3. PICTURE THIS..... <ul><li>You are camping with some friends when one of the party complains that he has been bitten on the leg by a snake </li></ul><ul><li>Your friends all know you have recently done the ELS Course . They look to you for help.… what are you going to do?? </li></ul>
  4. 4. FIRST AID <ul><li>Immobilise the patient </li></ul><ul><li>Pressure bandage </li></ul><ul><li>Immobilise the limb </li></ul>
  5. 5. Firm Bandage over the Bite Site
  6. 6. Extend Bandage Up the Limb
  7. 7. Immobilise the Limb
  8. 8. ENVENOMATION <ul><li>The patient is taken to the nearest hospital, which is a rural hospital. He arrives at the hospital 2 hours after the bite and is triaged to a resuscitation area of the Emergency Department. The patient, who is an amateur herpetologist , says that he believes it was a brown snake. He is complaining of headache, nausea and has vomited. </li></ul><ul><li>Outline your initial stabilisation </li></ul>
  9. 9. ENVENOMATION <ul><li>What do you do if the patient is unstable? </li></ul><ul><li>Directed history and examination? </li></ul>
  10. 10. HISTORY AND EXAMINATION <ul><li>Event </li></ul><ul><li>Symptoms </li></ul><ul><li>Past history </li></ul><ul><li>Directed examination </li></ul><ul><ul><li>CNS signs </li></ul></ul><ul><ul><li>Bleeding </li></ul></ul><ul><ul><li>Bite site </li></ul></ul>
  11. 11. INVESTIGATIONS <ul><li>Urine </li></ul><ul><ul><ul><li>U/A </li></ul></ul></ul><ul><li>Blood </li></ul><ul><ul><ul><li>Lab </li></ul></ul></ul><ul><ul><ul><li>Bedside (WBCT) </li></ul></ul></ul><ul><li>VDK </li></ul><ul><ul><ul><li>Bite site </li></ul></ul></ul><ul><ul><ul><li>Urine </li></ul></ul></ul>
  12. 12. VENOM DETECTION KIT (VDK) <ul><li>Cut a window in the bandage </li></ul><ul><li>Don’t wash or incise wound </li></ul><ul><li>Swab of bite site detects minute quantities of venom </li></ul><ul><li>Moisten swab in diluent </li></ul><ul><li>Rotate & rub over bite site and adjacent skin </li></ul><ul><li>Place swab stick into sample diluent bottle and shake it around </li></ul>
  13. 13. VENOM DETECTION KIT <ul><li>Tells you what type of antivenom to use if required </li></ul><ul><li>+ve VDK from bite site is not an indication for antivenom </li></ul><ul><li>-ve VDK from bite site does not exclude envenomation </li></ul>
  14. 14. RESULTS <ul><li>A swab of the bite site is taken for the VDK </li></ul><ul><ul><li>positive for tiger snake venom </li></ul></ul><ul><li>WCC 18.0 (neutrophilia), Hb 150, Plat 120 </li></ul><ul><li>Na 138, K 4.5, Urea 5.0, Creat 90 </li></ul><ul><li>CK 750 </li></ul><ul><li>PT 35, APTT 60, FDP’s elevated </li></ul><ul><li>Fibrinogen - low </li></ul>
  15. 15. ENVENOMATION <ul><li>Outline what specific treatment you would give. </li></ul>
  16. 16. WHICH ANTIVENOM? <ul><li>Identification of snakes by amateurs unreliable </li></ul><ul><li>Polyvalent or location specific if deteriorating and no VDK </li></ul><ul><li>Monovalent preferable - VDK may help </li></ul>
  17. 17. ANTIVENOM <ul><li>SEEK ADVICE </li></ul><ul><li>Premedication? </li></ul><ul><li>How is antivenom administered? </li></ul><ul><li>How much antivenom? </li></ul><ul><li>What dose for children? </li></ul><ul><li>When should pressure bandage be removed? </li></ul>
  18. 18. REMOVAL OF BANDAGE <ul><li>Don’t remove first aid bandage unless: </li></ul><ul><ul><li>Secure IV access </li></ul></ul><ul><ul><li>Antivenom of appropriate type and amount is at hand </li></ul></ul><ul><ul><li>Patient is clinically stable </li></ul></ul><ul><ul><li>A decision about antivenom use has been made. </li></ul></ul>
  19. 19. ONGOING CARE <ul><li>All snake bite victims must be admitted to an institution where laboratory testing and antivenom are rapidly available </li></ul><ul><li>Admit all envenomated patients to an ICU </li></ul>
  20. 20. QUESTIONS
  21. 21. IMPORTANT POINTS <ul><li>Don’t remove first aid bandage unless antivenom is available, an IV line is in place, the patient is clinically stable, and a decision about antivenom use has been made. </li></ul><ul><li>A +ve or -ve VDK from the bite site does not tell you whether or not the patient has been envenomated! </li></ul>
  22. 22. IMPORTANT POINTS <ul><li>When antivenom is needed, multiple doses are often required, particularly in the case of brown snake bite. The correct dose is that which is required to reverse the reversible symptoms, signs, and laboratory abnormalities. </li></ul><ul><li>Children require the same dose of antivenom as adults. </li></ul>
  23. 23. IMPORTANT POINTS <ul><li>Seek advice from Emergency Specialists in your region or the Poisons Information Centre. </li></ul><ul><li>Admit all patients with proven or suspected snake bite to a facility where there is rapid laboratory testing and antivenom available. </li></ul>

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