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APPROACH TO SNAKEBITE.pptx
- 2. Overview • Introduction • Speciesidentification • Clinicalassessment • Treatmentandmanagement • Take homemessage
- 3. Introduction • causelocaland/or systemicenvenomationthatcan result inalife-threateningmedicalemergency • prevalentinmanytropicalandsubtropical countries • trueepidemiology and theglobal burden measureof snakebite envenomationremainunknown • previous managementof envenomationdueto snakebite inour countryhasbeenachallenge dueto guidelines from othercountriesarenottailored toour local snake species • snakebite envenomationandthescientificresearchon antivenominMalaysiahaveimprovedtremendously in recentyearsespecially withtheaid of RECS (Remote EnvenomationConsultation Services)andVTRL (Venom and Toxin ResearchLaboratory)
- 4. Source: Guideline: Management of Snakebite, 2017. Ministry of Health Malaysia
- 5. Species Identification • Canberecognizedbytheirmorphologicalfeaturessuch assize,shape, colour,markingsandbehaviour • Properidentificationofthesnakeispossible onlyby examiningthesnakeifit waskilledorrestrainedand brought to thehospital • Anotheroption foridentificationis usinggood quality pictures • Dorsalview:takea picturefromabove • Ventralview:take apicturefrombelow(turn the snakeover) • Close-upoftheheadfromabove andthesides • Whenthesnakeorits pictureisnotavailable,thesnake speciesdeemedresponsiblefortheenvenomingshouldbe consideredusingavailable photographs ofvenomous snakes • ImageGalleryofSnakesofMedicalImportancein Malaysia producedbytheMalaysian Societyof Toxinology Classification Features Elapidae (cobras, kingcobra, kraits, coralsnakes, seasnakes long,thin,largesmooth symmetricalscales(plates) on thetop (dorsum) ofthehead, shortfixedfrontfangs,raise thefrontpartoftheirbody offtheground andspreadand flattentheneckto formahood. Viperidae (trueviper,pit viper) longfangs,the Crotalinaehavethelorealpit organ,to detecttheirwarm-bloodedprey. Natricidae(keelback) Mostdo notcausesignificantharm.Onespeciesof medicalimportanceinMalaysia is thered-necked keelback(Rhabdophis subminiatus), whichhasthe potential tocausesignificantcoagulopathy.
- 6. Venomous VS Non- venomous Snakes Venomous Non-venomous
- 7. Source: Guideline: Management of Snakebite, 2017. Ministry of Health Malaysia
- 14. History -Detailed history of the event -Behaviour and location will give important clues in indentifying the possible snake species
- 15. Clinical Features Toxins Mechanism of Action Signs and symptoms Neurotoxic (commonly by elapidae) • binds to nicotinic acetylcholine receptors at NMJ • Interference in Ca2+ channels • Binds enzyme acetylcholinester ase and prevent acetylcholine breakdown Descending type of paralysis: Ptosis, opthalmoplegia, cranial nerve palsy, aphonia, dysphagia, regurgitation through the nose, respiratory arrest, flaccid paralysis Cytotoxic (commonly by elapidae) • Myotoxic - disruption of cell membrane of skeletal muscles • Cardiotoxic - increases/ decreases heart rate • Nephrotoxic - glomerular and GBM damage Generalised severe myalgia, stiffness, tenderness, chest pain, shortness of breath, palpitations, dizziness, hypotension, shock, arrhythmia, localized necrosis, oliguria, anuria, dark coloured urine Haematotoxic (commonly by viperidae) • Promote or inhibit hemostatic mechanisms (activates prothrombin, factor X, factor V, fibrinolysis, consumptive coagulopathy) Prolonged bleeding, occult bleeding, petechiae, ecchymoses, stroke symptoms -The presentation is often complex -Symptoms and signs vary according to the species of snake, size/ age and the amount of venom injected
- 16. Examination -Thorough examination for local, general and systemic envenoming signs -Serial clinical assessment is more informative to guide management
- 19. Rate of Proximal Progression -Swellingoftenprogressesproximallyfromthebite site -Keeptwo ofthemostrecentlabelsonly
- 22. Investigations -Testsshouldberepeatedasindicated Source: Guideline: Management of Snakebite, 2017. Ministry of Health Malaysia
- 23. 20 minute whole blood clotting test (20WBCT): -Aquickbedsidetestforanunidentifiedbiteor whenapitviperbiteis suspected. -Whenlaboratory test forcoagulation profileisnot available METHOD i. Place2mls of freshly sampled venous blood inasmall, neworheat cleaned,DRY GLASS testtube. ii. Leave undisturbed for 20minutes atambient temperature, thentip thetubeonce. iii. If theblood hasnot clottedthepatientmay have coagulopathy. iv.Thetestmayberepeated asnecessary. *20WBCT result aloneshould not be usedasdeterminant forantivenom treatment
- 27. Disposition • Indicationforobservationandadmission: • Snakebitewithlocal and/orsystemicenvenomation • Venomous snakebite • Unidentified snakebite • Unidentified animal bite • Followinganon-venomoussnakebite,patientcanbe safelydischargedif: • The snakecanbepositively identified asanon-venomous speciesbyatrained expert. • The clinical condition of thepatientcorrelates withthe expectedeffectof abitefromtheidentified snakespecies. • The bitedidnotcauseanysignificant tissueinjury suchas lacerations orpersistentbleeding thatmayneedfurther treatment.
- 28. Management • Triagetored zone • Thegoalofprimaryassessment istoidentify any lifethreatening conditions.Resuscitation mustbe initiated immediately uponrecognition A±Airwaypatency B±Breathingeffort (poorrespiratory effort/bradypnoea) C±Circulation(lookforevidenceofshockandbleeding) D±Disabilityof nervoussystem(consciouslevel,muscleweakness) E± Exposureandenvironmentalcontrol
- 29. Management GENERALMANAGEMENT • Immobilizethebittenlimb • Position inneutralposition SUPPORTIVE MANAGEMENT • Steroidandantihistamines–ifallergic reaction • Analgesic–avoidNSAIDs • Antivenom • Anticholinesterases (IVAtropinesulphate 0.6mgforadults/50μg/kgforchildren followedbyIMNeostigmineBromide0.02 mg/kgforadults,0.04mg/kgfor children) • Antibiotic–localtissue necrosis/extensive injury
- 30. Venom Opthalmia • Anacutereactionoftheocularsurfacetissues tovenomsprayedintothe eyesbyNajasumatrana(equatorialspittingcobra). • Signs/symptoms:severe stingingpainanddiminutionofvision,excessive wateringineyes,severe blepharospasmandcornealerosions. • Treatment: • Irrigatetheaffectedeyewithcopiousirrigation • Fluoresceinstainmaybeusedtoexcludecornealabrasions. • Topicalanalgesics:tetracainedropsoradrenaline0.5%(ophthalmic solution) • Topicalcycloplegicdrops:atropineor scopalamine • Topicalantibiotics • Urgentopthalmologyreferral
- 31. Antivenom Therapy • Antivenom isthedefinitive treatment for envenomation • Derived typicallyfromtheplasmaof animalswhich havebeen immunisedwithvenom • Monovalent &polyvalent • Actsbybindingtovenom toxins (forming immunocomplexes), renderingthetoxins inactive whileenhancingtheireliminationfromthebody
- 32. Antivenom Therapy Systemic envenoming • Haemostatic abnormalities: Spontaneous systemic bleeding, coagulopathy, or thrombocytopenia • Neurotoxic signs:ptosis, external ophthalmoplegia, paralysis etc • Cardiovascular abnormalities: hypotension, shock, cardiac arrhythmia,abnormal ECG • Acute kidneyinjury:oliguria/anuria, rising blood creatinine/urea • Haemoglobin-/myoglobin-uria: darkbrown urine,urinedipsticks, other evidence of intravascular haemolysis or generalised rhabdomyolysis Local envenoming • Local swelling involving more than halfof thebitten limb (inthe absenceof atourniquet) within 48 hours of thebite. Swelling after biteson the digits(toes and especially fingers). • Rapid extension of swelling • Development of anenlarged tender lymph node draining thebitten • Indication:
- 37. TAKE HOME MESSAGE Bites by venomous snakes can cause local and/or systemic envenomation that can result in a life-threatening medical emergency Get an experienced physician or clinical toxicologist consultation regarding species identification and verification Preventive measures and proper treatment including the use of appropriate antivenom will lead to significant reduction in morbidity and mortality of snakebite envenomation
- 38. REFERENCE • Guideline: Managementof Snakebite, 2017. Ministryof HealthMalaysia
Notas del editor
- true epidemiology and the global burden measure of snakebite envenomation remain unknown and speculative due to the lack of reliable information on its incidence, morbidity and mortality RECS (Remote Envenomation Consultation Services), provide phone consultations (on 24/7 basis) to guide doctors in diagnosis and treating snakebite envenomation all over Malaysia; while a group of toxin researchers from the Venom and Toxin Research Laboratory (VTRL), University of Malaya have also actively engaged in the characterization of venom toxins and neutralization profiles of antivenom against our regional snake venoms
- Taken for the years 2010 to 2014, a total of 15798 snakebite cases had been reported in the country (Table 1). The number of deaths over the same period totaled 16, averaging 3 to 4 deaths per year. The states with the highest number of snakebite cases were Kedah and Perak, presumably associated with agricultural activities. Unfortunately, data showing number of cases that did not present to a health care facility is not available
- Some harmless snakes are morphologically similar to venomous snakes
- Clinically, the presentation of an envenomed patient is often complex because of the pathophysiological responses to the actions of different toxins in a venom. The toxic effects of snake venom have often been conveniently classified as neurotoxic, hemotoxic, cytotoxic, nephrotoxic, myotoxic descending type of paralysis
- A detailed history of the event surrounding envenomation is important for an accurate diagnosis. Snakes have different habitats and geographical distribution. Arboreial snakes are good climbers while certain species lack this ability. History regarding the snake’s behaviour and location will give important clues in indentifying the possible snake species.
- Clinically, the presentation of an envenomed patient is often complex because of the pathophysiological responses to the actions of different toxins in a venom. The toxic effects of snake venom have often been conveniently classified as neurotoxic, hemotoxic, cytotoxic, nephrotoxic, myotoxic. Symptoms and signs vary according to the species responsible for the bite, size/ age and the amount of venom injected. descending type of paralysis
- Thoroughly examine the patient for local, general and systemic envenoming signs. Serial clinical assessment is more informative to guide management. Examination of the bitten part: Bite mark, the number of puncture wounds or lacerations, the width of the puncture wound, number of rows of teeth marks seen on the skin should be documented. If the biting species is unknown, patient should be observed closely for at least 24 hours to allow recognition of the emerging pattern of symptoms, signs and results of laboratory tests
- Coagulation profile: APTT/PT and INR. Fibrinogen level and D-dimer can be sent if available. Coagulation profile should be repeated 6 hourly for suspected pit viper cases. Full blood count: Platelet count may be decreased in victims of envenoming by vipers. Serial FBC will reveal a drop in hemoglobin if there is significant bleeding. Renal profile: Serum creatinine is necessary to rule out renal failure. Also to detect electrolyte imbalance in patients with repeated vomiting. Early hyperkalemia may be seen following extensive rhabdomyolysis in sea snake bites. Creatine kinase: For early detection of rhabdomyolysis. Serial monitoring to monitor trend. Urinalysis: To assess for myoglobinuria, hematuria and proteinuria. Liver function test: Mild hepatic dysfunction is reflected in slight increases in serum enzymes after severe local muscle damage. ECG: To detect arrhythmia especially in envenoming involving Naja species bite. ABG: To monitor and assess respiratory function. To detect metabolic acidosis in renal failure. Arterial puncture is contraindicated in patients with suspected coagulopathy (viperidae).
- Coagulation profile: APTT/PT and INR. Fibrinogen level and D-dimer can be sent if available. Coagulation profile should be repeated 6 hourly for suspected pit viper cases. Full blood count: Platelet count may be decreased in victims of envenoming by vipers. Serial FBC will reveal a drop in hemoglobin if there is significant bleeding. Renal profile: Serum creatinine is necessary to rule out renal failure. Also to detect electrolyte imbalance in patients with repeated vomiting. Early hyperkalemia may be seen following extensive rhabdomyolysis in sea snake bites. Creatine kinase: For early detection of rhabdomyolysis. Serial monitoring to monitor trend. Urinalysis: To assess for myoglobinuria, hematuria and proteinuria. Liver function test: Mild hepatic dysfunction is reflected in slight increases in serum enzymes after severe local muscle damage. ECG: To detect arrhythmia especially in envenoming involving Naja species bite. ABG: To monitor and assess respiratory function. To detect metabolic acidosis in renal failure. Arterial puncture is contraindicated in patients with suspected coagulopathy (viperidae).
- Coagulation profile: APTT/PT and INR. Fibrinogen level and D-dimer can be sent if available. Coagulation profile should be repeated 6 hourly for suspected pit viper cases. Full blood count: Platelet count may be decreased in victims of envenoming by vipers. Serial FBC will reveal a drop in hemoglobin if there is significant bleeding. Renal profile: Serum creatinine is necessary to rule out renal failure. Also to detect electrolyte imbalance in patients with repeated vomiting. Early hyperkalemia may be seen following extensive rhabdomyolysis in sea snake bites. Creatine kinase: For early detection of rhabdomyolysis. Serial monitoring to monitor trend. Urinalysis: To assess for myoglobinuria, hematuria and proteinuria. Liver function test: Mild hepatic dysfunction is reflected in slight increases in serum enzymes after severe local muscle damage. ECG: To detect arrhythmia especially in envenoming involving Naja species bite. ABG: To monitor and assess respiratory function. To detect metabolic acidosis in renal failure. Arterial puncture is contraindicated in patients with suspected coagulopathy (viperidae).
- Coagulation profile: APTT/PT and INR. Fibrinogen level and D-dimer can be sent if available. Coagulation profile should be repeated 6 hourly for suspected pit viper cases. Full blood count: Platelet count may be decreased in victims of envenoming by vipers. Serial FBC will reveal a drop in hemoglobin if there is significant bleeding. Renal profile: Serum creatinine is necessary to rule out renal failure. Also to detect electrolyte imbalance in patients with repeated vomiting. Early hyperkalemia may be seen following extensive rhabdomyolysis in sea snake bites. Creatine kinase: For early detection of rhabdomyolysis. Serial monitoring to monitor trend. Urinalysis: To assess for myoglobinuria, hematuria and proteinuria. Liver function test: Mild hepatic dysfunction is reflected in slight increases in serum enzymes after severe local muscle damage. ECG: To detect arrhythmia especially in envenoming involving Naja species bite. ABG: To monitor and assess respiratory function. To detect metabolic acidosis in renal failure. Arterial puncture is contraindicated in patients with suspected coagulopathy (viperidae).
- Coagulation profile: APTT/PT and INR. Fibrinogen level and D-dimer can be sent if available. Coagulation profile should be repeated 6 hourly for suspected pit viper cases. Full blood count: Platelet count may be decreased in victims of envenoming by vipers. Serial FBC will reveal a drop in hemoglobin if there is significant bleeding. Renal profile: Serum creatinine is necessary to rule out renal failure. Also to detect electrolyte imbalance in patients with repeated vomiting. Early hyperkalemia may be seen following extensive rhabdomyolysis in sea snake bites. Creatine kinase: For early detection of rhabdomyolysis. Serial monitoring to monitor trend. Urinalysis: To assess for myoglobinuria, hematuria and proteinuria. Liver function test: Mild hepatic dysfunction is reflected in slight increases in serum enzymes after severe local muscle damage. ECG: To detect arrhythmia especially in envenoming involving Naja species bite. ABG: To monitor and assess respiratory function. To detect metabolic acidosis in renal failure. Arterial puncture is contraindicated in patients with suspected coagulopathy (viperidae).
- To optimise airway patency, perform head tilt chin lift manouver with adequate suctioning. Depending on patient’s conscious state, position patient in the left lateral, supine or propped up position to ensure airway is maintained. Administer oxygen with an appropriate-delivery-device as indicated. Consider inserting an oropharyngeal airway to aid airway patency. Do not attempt this if gag reflex is still present Neurotoxic envenoming can lead to paralysis of the respiratory muscles and cause respiratory failure. Positive pressure ventilation via bag valve mask may be required and must be followed by definitive airway insertion when indicated. Profound hypotension and shock can be due to direct cardiovascular effects of the venom or secondary effects, such as hypovolaemia, release of inflammatory vasoactive mediators and haemorrhagic shock. Profound hypotension can also rarely be caused by primary anaphylaxis induced by the venom itself. In skeletal muscle breakdown (rhabdomyolysis), hyperkalemia can also lead to cardiac arrest. Cardiopulmonary resuscitation should be initiated if patient is in cardiac arrest. At least two large bore intravenous cannulas should be inserted with appropriate fluid resuscitation. Look for any source of external bleeding and apply appropriate method of bleeding control. Cardiac monitor shall be attached to look for arrhythmias and management shall be according to advanced life support management. Close serial monitoring of blood pressure, heart rate, respiratory rate, SpO2, pain score, PEFR (if applicable) every 5-15 minutes in acute stage is required. Temperature monitoring can be done four hourly. Use a snakebite chart as in appendix. Monitor urine output hourly. Note the colour changes of the urine in sea snake bites.
- General Splint Level of heart Supportive Prophylactic steroids & antihistamines only if anaphylactic/allergic reaction Analgesia – avoid NSAIDs Antivenom – if indicated Anticholinesterase – in neurotoxic cobra bites, atropine sulphate, neostigmine
- General Splint Level of heart Supportive Prophylactic steroids & antihistamines only if anaphylactic/allergic reaction Analgesia – avoid NSAIDs Antivenom – if indicated Anticholinesterase – in neurotoxic cobra bites, atropine sulphate, neostigmine
- General Splint Level of heart Supportive Prophylactic steroids & antihistamines only if anaphylactic/allergic reaction Analgesia – avoid NSAIDs Antivenom – if indicated Anticholinesterase – in neurotoxic cobra bites, atropine sulphate, neostigmine
- General Splint Level of heart Supportive Prophylactic steroids & antihistamines only if anaphylactic/allergic reaction Analgesia – avoid NSAIDs Antivenom – if indicated Anticholinesterase – in neurotoxic cobra bites, atropine sulphate, neostigmine