IDENTIFICATION
HABITAT
Brown snakes ( Pseudonaja spp.) are distributed throughout mainland Australia. They are not found in Tasmania or on the islands off the southern coast of Australia. They may be found in essentially all habitats, including urban and metropolitan areas.  |
INTERVENTION CRITERIA
Medical assessment and observation, preferably in an advanced care facility, is recommended for: - Any individual bitten or suspected to have been bitten by a snake |
All patients require medical attention. |
Even trivial looking bites may result in severe envenoming; asymptomatic patients following possible envenoming must be observed for a minimum of 12 hours and should be observed overnight.   Patients must be closely observed for the onset of symptoms including: Coagulopathy Bleeding/ooze from bite or venepuncture sites Bleeding gums Hematuria Paralysis (may be subtle) Ptosis (drooping eyelids) Ophthalmoplegia (paralysis of motor nerves of the eye) Bulbar palsy Descending flaccid paralysis Acute kidney injury |
The coagulation screen and blood investigations along with a neurological examination must be performed upon presentation, 1 hour after removal of the pressure bandage, and repeated at 6 hours and 12 hours after the bite.  If at 12 hours post-bite all the blood tests are normal and there is no clinical signs of neurotoxicity the patient is eligible for discharge.  The patient should be advised to return if there is any indication of illness including change in their urine color or if they develop any muscle pain, tenderness, or weakness. Removal of Pressure Bandage with Immobilization First Aid If envenoming is evident, do not remove pressure bandage with immobilization first aid until antivenom has been administered.  If there are no clinical or biochemical signs of envenoming only remove pressure bandage with immobilization first aid once an IV line has been inserted and antivenom and advanced resuscitation facilities are at hand.    A bite site swab can be saved for possible venom detection kit (VDK) testing if evidence of envenoming becomes evident. However, VDK analysis is not always necessary. Determination of the appropriate antivenom required to treat an envenomed patient can often be determined through clinical and laboratory features of envenoming and the geographical location of the snakebite. Once the pressure bandage is removed repeat blood tests at 1 hour after removal.  If these results are normal and there are no signs of neurotoxicity repeat blood tests again at 6 hours (unless already > 6 hours) and 12 hours after the bite.  If clinical signs or biochemical findings indicate systemic envenoming then antivenom should be administered.  If at 12 hours post-bite all the blood tests are normal and there is no clinical signs of neurotoxicity the patient is eligible for discharge.  Adequate hydration is required to reduce the incidence of renal damage.  Hydration should be maintained through administration of oral or intravenous fluid to ensure a good urine output. Normal (0.9%) saline dose CHILD Adjust adult dose to body weight ADULT Initial fluid load 1 L IV over 2 to 3 hours Continue infusion at 100 to 150 mL IV per hour for 6 to 12 hours |
Be circumspect when inserting IV lines, as there will be continued oozing from all sites until the coagulopathy reverses, which will be at least 6 hours, usually more. Avoid insertions in sites where bleeding cannot be easily controlled, such as subclavian, femoral, and jugular veins. |
In all cases of suspected snakebite conduct: Blood investigations Snake venom detection kit test depending on geographical location of snakebite All patients must then be observed for a minimum of 12 hours.  Snake Venom Detection Kit Identification Urine may be tested using the snake venom detection kit if there is evidence of significant systemic envenoming and a bite site swab is either unavailable, or has tested negative. Urine may sometimes give false positives  and should not be tested in patients who do not have evidence of systemic envenoming.  If pressure bandage with immobilization first aid has been applied, do not remove the bandage, rather, cut away a section immediately over the bite area and swab for venom detection.  Retain the cut section of bandage as it may later be used for further venom identification. Insert a secure intravenous line and take blood for: Coagulopathy screen: International normalized ratio (INR) Activated partial thromboplastin time (aPTT) Fibrinogen concentration Quantitative D-dimer/Fibrin degradation products Point of care testing devices for coagulation studies have been shown to produce false positive results in cases of snakebite, and should not be used. Full blood count (FBC) including: Platelets White blood cells (especially absolute lymphocyte count) Serum electrolytes including: Potassium Sodium Serum urea Serum creatinine Serum creatine kinase (CK) Collect urine Visually check for hemoglobinuria/myoglobinuria (dark-red/brown coloration) May be required for subsequent Snake Venom Detection Kit testing |
Admission to an intensive care environment is recommended for patients who develop any signs of envenoming or abnormal blood results. |
TREATMENT
TREATMENT SUMMARY
Consultation with a medical toxicologist (at the bedside or through a Poison Center) is advised for this poisoning as toxicity can be life-threatening. |
Rapid and effective diagnosis is imperative. While 75% of brown snake bites do not lead to systemic envenoming, all cases should be considered potentially lethal, and all must be admitted to a hospital capable of providing definitive care. Application of pressure bandage with immobilization first aid prior to initial patient movement can be life-saving in conjunction with subsequent antivenom administration. Cardiac dysrhythmia/arrest and seizure or collapse may require immediate management. If there is evidence of systemic envenoming, administration of appropriate antivenom to neutralize circulating venom is crucial. Further supportive care may be required. Venom induced consumptive coagulopathy is characteristic of Australian brown snake envenoming, although hemorrhage may not be clinically apparent unless bleeding from a traumatic injury. Any injury to the head (possibly associated with a post-bite collapse) is a potential source of intracranial hemorrhage. Routine administration of blood products including fresh frozen plasma is not indicated, unless there is uncontrolled life-threatening bleeding. Any factor potentially causing hypertension should be avoided. Intravenous fluid hydration is required to ensure renal perfusion; renal damage is a concern and should be managed following standard protocols if antivenom does not prove adequate. Paralysis is uncommon but may be heralded by onset of ptosis and ophthalmoplegia several hours after a bite. Antivenom may prove beneficial but may not fully reverse established paralysis. Pain is unlikely to be a feature; avoid drugs with anti-platelet function including aspirin and NSAIDs. Potent analgesics including opioids that potentially produce respiratory depression are usually not required, but can be used in monitored clinical environments. Infection is uncommon and therefore prophylactic antibiotics are not required; if infection becomes evident then an appropriate antibiotic should be administered. Tetanus status should be reviewed, and a booster administered if required; to avoid iatrogenic intramuscular hematoma do not give any IM injections until coagulopathy is reversed. Myolysis is not a feature of brown snake envenoming. Serum sickness may occur following antivenom administration; follow up and/or steroid treatment may be required. |
EMERGENCY STABILIZATION
Ensure Adequate Cardiopulmonary Function |
Ensure the airway is protected if compromised (intubation may be necessary). |
Immediately establish secure intravenous access. |
Be circumspect when inserting IV lines, as there will be continued oozing from all sites until the coagulopathy reverses, which may take at least 6 hours, usually more.  Avoid insertions in sites where bleeding cannot be easily controlled, such as subclavian, femoral, and jugular veins.  |
Pressure Bandage with Immobilization First Aid |
- Reassure the patient and ensure they remain still.  - Remove any watches, rings, bracelets, or other jewelry from the bitten limb.   - A broad elasticized compression bandage should be applied over the bitten area about as firmly as that used for a sprained ankle but not so tight that circulation is compromised. Elasticized bandages are preferable,  but crepe bandages, clothing strips, towels, or pantyhose will suffice in an emergency.   - It is very important that the patient is not moved. A compression bandage should be applied over clothing - rather than move an arm or leg.  - Bandage upward from the lower portion of the bitten limb. Apply the bandage as far as possible up the limb.  - If bite is on the arm, bandage the arm with the elbow bent and leave the tips of the fingers unbandaged to allow circulation to be checked. Bind a splint to the forearm and immobilize the arm with a sling.  - If the bite is on the leg, leave the tips of the toes unbandaged to allow circulation to be checked. Immobilize the leg by bandaging a splint to the limb to prevent movement.  - On the overlying bandage mark the location of the bite.  - Ensure the patient is told not to move the affected limb at all.   - Transport (preferably an ambulance) should be brought to the patient to prevent movement. If this cannot be done, the patient should be carried rather than walk.  - Do not give alcohol, fluid, or food by mouth. If the patient will not reach medical care for a long period, only water should be given by mouth.  - Transport to hospital.  - Tourniquets should not be used. The bite site should not be washed, cleaned, cut, sucked, or treated with any substance.  |
Cardiac arrest or dysrhythmia are likely short-lived as the precipitating blood clot will be dissolved by fibrinolysis.  Resuscitation should follow standard procedures for cardiac arrest. |
Toxic seizures are generally self-limiting and are unlikely to require specific treatment.
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CHILD Hypotension in children is determined by age and systolic blood pressure Age | Hypotension if Systolic Blood Pressure (mm Hg) is: | 0 to 28 days | < 60 | 1 to 12 months | < 70 | 1 to 10 years | < 70 + (age in years x 2) | > 10 years | < 90 |
Administer an isotonic crystalloid fluid 10 mL/kg IV over 5 to 10 minutes If the systolic blood pressure does not return to the normal range, give a further 10 mL/kg body weight of the isotonic crystalloid over 5 to 10 minutes. The intraosseous route can be used if IV access is difficult or delayed. ADULT Administer a bolus of isotonic crystalloid fluid if systolic blood pressure is less than 100 mmHg. Isotonic crystalloid fluid dose: 20 mL/kg IV over 5 to 10 minutes If the systolic blood pressure does not return to the normal range, give a further 10 mL/kg body weight normal saline over 5 to 10 minutes. The intraosseous route can be used if IV access is difficult or delayed. |
Coagulopathy screen Full blood count Serum electrolytes Serum urea Serum creatinine Serum creatine kinase (CK) Heart rate Blood pressure Respiratory function 12 lead ECG Fluid balance Plasma glucose Head CT scan (if altered mental status) |
DECONTAMINATION
Decontamination Not Recommended |
ANTIVENOM
Australian Polyvalent Snake Antivenom |
Antivenom is most effective when administered early following snakebite, and is less likely to be beneficial once major envenoming syndromes have been established.  Brown Snake Antivenom is the preferred antivenom. Polyvalent Snake Antivenom is an alternative if a suitable monovalent antivenom is not available. |
In the majority of cases of brown snake bite, antivenom will not be required.  Antivenom administration is indicated in any patient where there is: History of unconsciousness, collapse, seizure, or cardiac arrest Coagulopathy INR > 1.3, prolonged bleeding from wounds or venepunctures Neurotoxic paralysis Any flaccid paralysis including ptosis, opthalmoplegia, limb or respiratory muscle weakness (unless present without worsening for 6 hours) Antivenom administration may be indicated in the following circumstances. In these instances discussion with a medical toxicologist is recommended. Renal damage Elevated creatinine and urea Any abnormality of APTT, INR, D-dimer, FBC Significant symptoms including headache and vomiting Any patient who appears systemically unwell |
In most instances of Australian snakebite an adequate initial dose of antivenom will be sufficient and past practices of multiple repeat doses are both unnecessary and potentially hazardous.  Nevertheless, it is important that the initial dose of antivenom not be considered the end of treatment and investigation. |
Initial Brown Snake Antivenom Dose CHILD and ADULT Patients must be closely monitored for anaphylaxis during and for 30 minutes after the infusion.  Further Brown Snake Antivenom Doses Current evidence indicates it may take at least 6 hours for evidence of recovery to become reliably detectable following antivenom.  Therefore, unless there is clear clinical indication for earlier testing, repeat blood tests and conduct a careful neurological examination at 6 hours post-antivenom. If measured parameters are stable or are improving, further antivenom is not immediately required. If there is evidence of worsening paralysis, coagulopathy, myolysis, or kidney injury, it is recommend that advice from a medical toxicologist is obtained regarding whether further antivenom therapy is required. Further blood testing and an on-going schedule of repeat examinations every 12 hours is appropriate for at least 24 hours post-antivenom or longer if envenoming has not completely resolved. Polyvalent Snake Antivenom For Polyvalent Snake Antivenom, follow the same dosage and administration guidelines as for Brown Snake Antivenom outlined above. Each vial of Polyvalent Antivenom carries the same neutralizing capacity as one vial of Brown Snake Antivenom. Note that polyvalent antivenom is a greater volume of sera and therefore more likely to precipitate an adverse reaction; it is also more expensive than monovalent antivenom. In small children, high doses of polyvalent antivenom may be impractical because of fluid overload issues. |
There is no absolute contra-indication to this potentially life-saving intervention. Pregnancy is not a contraindication to antivenom administration.  Those at increased risk of severe reaction include patients with history of: Previous reaction to antiserum Asthma Atopy |
Closely monitor the patient for indications of anaphylaxis including: Rash Erythema Pruritus Urticaria Rhinitis Conjunctivitis Vomiting Diarrhea Wheeze Dyspnea Hypotension Angioedema Shock Airways obstruction |
Patients should be made aware of the signs and symptoms of serum sickness including: Rash Fever Joint aches Pains Malaise |
If more than 25 mL of Brown Snake Antivenom is administered, prophylaxis with an oral steroid such as prednisolone may be considered, and follow-up arranged.   Commence prophylaxis on day 2 to 3 post-bite. |
Prednisolone dose CHILD 1 mg/kg (up to 50 mg) per day orally for 5 days ADULT 50 mg per day orally for 5 days |
SIGNS AND SYMPTOMS
Initial systemic symptoms can include nausea, vomiting, abdominal pain, headache, and dizziness.     Sudden loss of consciousness, typically with spontaneous recovery, may occur early in the course of envenoming.   There is potential for hypotension, cardiac dysrhythmia, and rarely arrest.    Bleeding and/or ooze from the bite site or subsequent venepuncture is an early indication of venom induced consumption coagulopathy (VICC), which is the hallmark of brown snake envenoming.    This coagulopathy may potentially lead to complete defibrination and non-clotting blood. International normalized ratio (INR) and activated partial thromboplastin time (aPTT) will be prolonged, fibrinogen low to absent, and fibrin degradation products (FDP) and D-dimer immunoassay elevated.       Although hemorrhage is a major concern, spontaneous bleeding is uncommon to rare.   Thrombotic microangiopathy with thrombocytopenia and microangiopathic hemolytic anemia may additionally occur,  but is not common; platelet counts typically remaining normal in most cases. Neurotoxicity is rare and typically only results in mild effects such as ptosis.  Seizure may occur, more commonly in children, but it does not appear to be related to neurotoxins. Acute kidney injury may occur  and it more commonly develops in adults. It appears that most, possibly all cases of acute kidney injury are not primarily caused by venom nephrotoxicity but likely secondary to other effects of envenoming such as thrombotic microangiopathy.  Myolysis is not typically a feature of brown snake envenoming.   |
Clinical effects usually develop following a dermal exposure (bite). Snakebite to the eye or contamination of the eye with snake venom is an unlikely route of exposure. |
Onset/Duration of Symptoms |
Coagulopathy typically resolves over 12 to 18 hours.   Paralysis following snakebite may take days or weeks to resolve.  |
The following are typical features indicating severity in patients known to be envenomed, but it is important to note that the isolated presence of (particularly mild) features does not always indicate that envenoming has occurred. Mild Pseudonaja Envenoming | Moderate Pseudonaja Envenoming | Severe Pseudonaja Envenoming | Nausea Vomiting Abdominal pain Headache Confusion Drowsiness | Pallor Sweating Ptosis Ophthalmoplegia Tachycardia Hypotension Oliguria | Venom induced consumption coagulopathy Microangiopathic hemolytic anemia Intracranial hemorrhage Acute renal failure Paralysis Respiratory failure Cardiac arrest |
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Do Not Archive. This document is current on day of issue,
NZ: 23.May.2022 |