Transcript Management of Snake Bites - Medical Council of Guyana

MANAGEMENT OF SNAKE BITES
Dr. Cheetanand Mahadeo
Registrar General Surgery
GPHC
RELEVANCE OF TOPIC
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The people most affected by rabid dog bites, snake
bites and scorpion stings usually live in poor rural
communities where medical resources are often
sparse. Because they lack a strong political voice,
their problems tend to be overlooked by politicians
and health authorities who are based in capital cities
and are poorly informed about major public health
issues affecting rural areas. Consequently, the impact
of these health issues, although dramatic and
economically significant, does not appear as a priority
in the design of national public health programmes.
These are therefore the most neglected among today’s
neglected global health problems…
Rabies and Envenomings, a neglected public health issue, World Health Organization,
http://www.who.int/bloodproducts/animal_sera/Rabies.pdf
DISCLAIMERS
Independent Study and analysis
 No funding provided
 If any medication is recommended or condemned
it was based on pharmacological evidence and not
commercial influence
 Only GPHC data was studied
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INTERNATIONAL EPIDEMIOLOGY
Only 15% of approximately 3000 species of
snakes worldwide are dangerous to humans
 Age range 11-50 yrs
 Predominantly Males
 Most common site being Lower Limbs
 Summary: “5.4 million bites, about 2.5 million
envenomings and over 125,000 deaths annually” ,
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A Kasturiratne et al The Global Burden of Snakebite: A Literature Analysis and Modelling Based on
Regional Estimates of Envenoming and Deaths, PLOS Medicine.
http://www.plosmedicine.org/article/info%3Adoi%2F10.1371%2Fjournal.pmed.0050218;jsessionid=66B
81B3E56F5DABADB52D86E51BE334F
CLASSIFICATION OF SNAKES
Colubridae: most non-venomous snakes e.g grass
snake
 Elapidae: Venemous: e.g. Cobras, Kriats, Mambas,
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Coral snakes (present in Guyana)
Viperidae: Venomous: e.g. Rattlesnakes, Adders,
Vipers (in Guyana, the notorious Labaria)
 Hydrophidae: sea snakes
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Modified classification from: W. Rushin, Taxonomy of snakes, 2700 species, 2004; pg 3
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B S Gold et al, Bites of venomous snakes, N Engl J Med, Vol. 347, No. 5, August 1st 2002.
BOTHROPOS ATOX (LABARIA)
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Photographs Of Labaria Snake from Iwokrama,
Guyana
GUYANA BLACKBACK CORAL SNAKE
(LEPTOMICRURUS COLLARIS)
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Photograph taken in Region 1 Guyana
VENOM TOXICOLOGY
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An extremely complex mixture of enzymes, peptides,
glycoproteins and metal ions.Proteolytic
enzymes,Arginine ester hydrolase,Thrombin-like
enzyme,Collagenase,Hyaluronidase,Phospholipase
A2(A), Phospholipase B, Phosphomonoesterase
Phosphodiesterase, Acetylcholinesterase,
RNaseDNase, 5'-Nucleotidase, NAD-ucleotidase, LAmino acid oxidase,Lactate dehydrogenase…
Component
Action
Serine Proteases
Haemolysis
Other Proteases
Haemolysis
Phospholipase A2
Myotoxic, Cardiotoxic, Neurotoxic,
increases vascular permeability
Hyaluronidase
Tissue necrosis
Neurotoxins
Synaptic inhibition and paralysis
UNDERSTANDING ANTIVENOM(OR
ANTIVENIN OR ANTIVENENE)
A biologic product used in treatment of venomous
bites/stings
 The principle of antivenom is based on that of
vaccines; antibodies against proteins
 Monovalent (when they are effective against a
given species' venom) or
 Polyvalent (when they are effective against a
range of species, or several different species at
the same time).
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PRODUCTION OF ANTIVENNIN
Made according to WHO Biological Guidelines
and Good Manufacturing Practices
 Venom injected into Horses or Sheep
 Antibodies are harvested from these animals
 Freeze dried for reconstitution
 Some contain whole IgG others fragments of IgG
(Fab or Fab2)
 Binds to circulating venom components blocking
their attachment to receptors
 complexes are removed by Reticuloendothelial
system
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C D Richard, (3rd Ed.) Medical Toxicology, Lippencot-Williams-Wilkins, 2009, pg 250-251
SYMPTOMATOLOGY/SIGNS OF ENVENOMATION*
Hematoxic (Labaria)
Neurotoxic (Coral Snake)
•Intense pain
•Edema
•Weakness
•Numbness/paraesthesia
•Tachycardia
•Ecchymosis
•Fasciulations
•Metallic taste
•Confusion
•Hypotension/shock
•Renal failure
•Bleeding diathesis
•DIC
•Local necrosis
•Blebs
•Minimal pains
•Ptosis
•Weakness
•Numbness/paraesthesia
•Diplopia
•Disphagia
•Hypersalivation
•Diaphoresis
•Hyporeflexia
•Respiratory depression
•Paralysis
GREGORY JUCKETT, M.D., M.P.H., and JOHN G. HANCOX, M.D Am Fam Physician. 2002 Apr 1;65(7):1367-1375
GRADING OF A SNAKE BITE (HAEMOTOXIC)
Grade
Presentation
0
Punctures or abrasions; some pain or tenderness at the bite
1- Mild
Pain, tenderness, edema at the bite; perioral paresthesias may
be present
2 Moderate
Pain, tenderness, erythema, edema beyond the area adjacent
to the bite; often, systemic manifestations and mild
coagulopathy
3 Severe
Intense pain and swelling of entire extremity, often with
severe systemic signs and symptoms; Coagulopathy
4 Life
Threatening
Marked abnormal signs and symptoms; severe coagulopathy
DIC
GREGORY JUCKETT, M.D., M.P.H., and JOHN G. HANCOX, M.D, Am Fam Physician. 2002 Apr 1;65(7):1367-1375.
PATHOPHYSIOLOGY OF SNAKE BITES
Enzymatic proteins in venom causes manifestations.
 Neurotoxins e.g coral snake venom, ultimately causes
respiratory arrest.
 Specific details
 (1) hyaluronidase allows rapid spread of venom
through subcutaneous tissues by disrupting
mucopolysaccharides;
 (2) phospholipase A2 plays a major role in hemolysis
secondary to the esterolytic effect on red cell
membranes and promotes muscle necrosis; and
 (3) thrombogenic enzymes promote the formation of
a weak fibrin clot, which, in turn, activates plasmin
and results in a consumptive coagulopathy.
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J White, Snake venoms and coagulopathy, J Toxicon 24(2005); 951-957
MANAGEMENT OF THE SNAKE BITTEN
PATIENT
MANAGEMENT BEGINS IN THE FIELD
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Prevention of snake bites
Proper boots and leather leggings in snake infested
areas
 Snakes generally bite only when threatened/provoked
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FIRST AID GUIDELINES
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First Aid: summary of guidelines*
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Remove patient from area
Do not attempt to capture snake for identification
Calm the patient and Call for help
Do not give alcohol or anti-inflammatory medications
Remove constrictive clothing
Splint limbs to minimize movement
NO ICE PACKS
NO TORNIQUETS
DO NOT INCISE BITE SITE
DO NOT SUCK WOUND TO REMOVE POISON
*American Medical Association, American Red Cross, National Health and Research
Council Australia, Indian Ministry of Health Snake bite Protocol 2007
WHAT DO WE NEED TO UNDERSTAND
ABOUT SNAKE BITES?
Envenomation is a medical emergency
 All principles of initial emergency care applies
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Rapid Triage as IMMEDIATE
ABC’s to Stabilize Patient
Specific treatment if available
Early referral to MEDICAL staff.
Early identification of the type of toxicity and
management
Management will be symptom guided if the type
of snake is unknown
ABCDE OF TRAUMA CARE
Examine and manage the Airway
 Examine quality of Breathing and Maintain
function
 Monitor for signs of Circulatory compromise
 Assess for Neurologic Dysfunction
 Examine the patient thoroughly for multiple sites
of Exposure (>1 bite)
OXYGEN, MONITORS, IV FLUIDS FOR ALL
UNTIL SEVERITY OF ENVENOMATION IS
QUANTIFIED
Enquire about Tetanus Immunization in HPI
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THESE PATIENTS ARE IN PAIN!!
Oral analgesia and IV narcotics should be
considered
 DO NOT ADMINISTER ASPIRIN OR NSAIDS
 DO NOT GIVE DICLOFENAC OR OTHER
INTRAMUSCULAR MEDICATIONS
 Splint the bite area if possible and remove all
constricting bandages/tourniquets
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ROLE OF NEOSTIGMINE
Anticholinestrase & prolongs life of Ach - which
can reverse resp.failure & neurotoxic symptoms (
post synaptic )
 Neostigmine test : 1.5 -2.0 mg IM preceeded by
0.6 mg atropine IV
• Observe for 1 hr
• If victim responds , continue 0.5 mg Neostigmine
IM ½ hrly with 0.6 mg Atropine IV over 8 hrs
• If no improvement in symptoms after 1 hr ,
stop Neostigmine
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WHAT BASELINE LABORATORY TESTS?
Haemoglobin: anaemia
 White cell count/differential: infective process
 Blood film: identify fragmented RBC’s
 Platelet count: thrombocytopenia
 Bleeding time/clotting time: bleeding diathesis
 Prothrombin time: bleeding diathesis
 Renal function: elevated creatinine,
hyperkalemia
 Urinalysis: hematuria
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ADDITIONAL INVESTIGATIONS
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If severity requires or clinical examination suggests
the need:
ECG- severe bradycardia, ischemia etc
 Arterial blood Gas: severe acidosis can be present
 Chest X-ray: pulmonary edema, effusion or hemorrhage
 CT scans, esp. head: Intracranial bleeds can occur
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AFTER STABILIZATION, WHAT DO WE DO?
Admit for serial clinical/laboratory assessment
 Which ward? Usually general medical ward. The
ward is determined by the severity of the
envenomation and the patient’s specific
requirements eg. Ventilator support, Holter
monitoring, continuous oximetry etc.
 Seek consultation early! This includes:
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Toxicologist
 Hematologist
 Orthopedics
 Intensivist etc.
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ANTIVENOMS: TO GIVE OR NOT TO GIVE?
Antivenoms are life saving; give early
CAVEAT! Give the correct antivenom for the bite.
Polyvalent multiple genus/species generally do
not work well and the patient can have life
threatening reactions.
e.g. the Rattlesnakes of USA antivenom may have
no use in the South American Vipers.
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NO SPECIFIC ANTIVENOM IN GUYANA
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SUERO ANTIBOTROPICO POLIVALENTE
(Equine); Peruvian Antivenom
Bothrops atrox Common Lancehead, Fer de
lance
Bothrops brazili Brazil’s Lancehead Bothrops
pictus Desert Lancehead, Bothrops barnetti
Barnett’s Lancehead, Bothrocophias hyoprora
Amazonian Toadheaded Pit-viper
 B.atrox-Lachsis equine (Fab')2 antivenom,
Fundacao Ezequiel Dias, Minas Gerais State,
Brazil
HOW TO USE ANTIVENOM
Step
Proced.
Sensitivity test no
Pre-Med
Comment
Apart from the rare cases of a pre-existing
sensitivity, e.g. to horse serum, sensitivity tests
(intradermal, intraconjunctival) have no
predictive value for an antivenom reaction
(Malasit et al. 1986)
Adren.
Patients with atopy and previous reactions to
Steroids, products from Equine sources are at risk
Antihist.
Speed of Adm.
IV,
5ml/min
Dose
This is guided by degree of envenomation and the
manufacturers usually recommend doses depending on the
concentrations of Fab within antivenom.
Cautions
Most effective as an IV administered medication
Anaphylaxis can occur
http://www.vapaguide.info/page/38
DRUGS OF CONTROVERSIAL/UNPROVEN
VALUE
Non-specific antivenoms
 Corticosteroids: hydrocortisone,
prednisone,(steroids have a role in management
of type III hypersensitivity reactions that may
occur 7-21 days after a snake bite)
 Antihistamines and
 Vitamin K
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REASSURING FACTS
Not all venomous snake bites will have venom
injected (“Dry Bite”);
 Amount of venom depends on several factors:
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How hungry ?
 How angry?
 How threatened?
 How long since the last bite?1
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No consensus, but approximately 20% of
venomous snake bites will have no venom
injected.2
1.http://reference.medscape.com/features/slideshow/snake-envenomation
2. Longo et al, Harrison’s Principles of internal Medicine, 18th Edition, MvGraw-Hill Co. 2012:
Sect. 18, ch.396:
THE LOCAL ARENA
N= 240 cases from Jan 2010 to Dec 2012
 Approximately 80 cases/year seen at GPHC
 Males =153, Females = 87
 Average age of victim = 33.5 with range of 5/12 to
76
 Average Hb = 12.3 with range from 2.2g/dL to
18.1g/dL
 WBC mean 9954; range 3600- 23000
 Platelet mean 244 000; range of 8000 – 500 000
 Average duration of hospitalization 4.75 days
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BT, CT ordered for almost all patients
 PTT, PT, INR ordered for 4 patients (all values
elevated)
 Total Packed cells transfused = 28 units
 Total platelets transfused 4 Units
 Total Plasma 460 Units; average 2 u per patient
 Antivenom administered to 1 patient
 18 patients received corticosteroids (16
hydrocortisone and 2 prednisone)
 34 patients received Vitamin K
 5 patients received Desmopressin
 6 patients had surgical intervention (drainage of
Hematoma, Compartment syndrome,
Debridement and skin grafting)
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5 patients had HDU monitoring
 1 patient had ICU management
 100% patients received antibiotics with the most
common combination being Cloxacillin/Flagyl or
Augmentin/Clindamycin; few patients received
3rd generation cephalosporins
 14 patients received NSAIDS orally and 1 patient
received Novalgin IV; all others had IV morphine
or pethidine or oral Tramadol in combination
with Paracetamol.
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DEATHS
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5 patients died (N=240)
2 = Suspected Cerebral hemorrhage
 3 = Pulmonary Hemorrhage with their bleeding
diathesis and DIC
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All were over 60 years old
 All came 24 hrs after the bite
 All had signs of multiple organ failure (elevated
transaminases and creatinine average of
3.5[range 0.5-1.5])
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ARE THERE ANY HIGH RISK AREAS IN GUYANA?
WHAT AGES WERE AFFECTED?
60
52
49
50
40
51
37
32
30
Series1
20
10
9
51 - 60
>60
10
0
0 -10
11 20
21 -30
31 - 40
41 - 50
SIMPLE CASES
EXTREME CASES
ELAPIDAE (CORAL SNAKE BITE): FULL
VENTILATORY SUPPORT
AMPUTATED ARM IN LABARIA BITE
Severe life threatening problems and untreated
compartment syndrome can lead to this situation
SEVERE TISSUE NECROSIS; LABARIA BITE
DEBRIDEMENT /SKIN GRAFT
Photographs by Dr. Shilendra Rajkumar, Registrar, Plastic
Surgery, GPHC
SUMMARY
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Management begins in the field
Emergency triage as immediate
ABCDE takes priority
Tetanus prophylaxis
Early administration of Antivenom IF specific
Close monitoring of coagulation profile
Response guided supportive care
Clotting factors to replace that consumed Plasma or
Cryoprecipitate (not a substitute for antivenom but
useful)
Avoid dubious medications: Steroids, Antihistamines
and Vitamin K
Early/appropriate consultation with specialty
THANK YOU. QUESTIONS?