35006_scorpion stings _ snake bites by xiaoyounan


									KAAUH Jeddah

   Norah A. A. Khathlan MD
     Pediatric Intensivist
        Snake bites
Snakes are strict carnivores & venomous at birth.
Snakes are deaf & almost blind.
Sense of smell is high.Sensitive to vibration
Immobile at temps < 8°C cannot survive at > 42°C
Amount of venom released based on size of victim.
25-75% release of venom on biting humans.
Speed of strike is around 8ft./sec
Rattle snakes may strike any positions & repeatedly
Injection rather than bite.

Approximately 15% of 3000 types
High morbidity & low mortality.
   Nearly 100 000 deaths annually world wide
Males 17-21 years old.
98% on extremities, esp. hands & arms.
Usually provoked.
Mostly during spring.
               Snake bites
Epidemiology in the USA:
• Total: 45,000 snake bites in U.S. per year
     50% in Pediatrics patients.
• Venomous bites: 8000 in U.S. per year
• Deaths from snake bite in U.S.: 12 or less per
     None in Pediatrics.
• Envonomation occurs in 75% of U.S.
  poisonous snakebites
         Snake bites

in Saudi Arabia:
 Naja Naja arabicus “Copra”
 Echis carinatus & coloratus.

 Walterinnesia aegyptia.

 Bitis arietans.

 Cerastes cerastes.
        Snake bites
Snake Venom is primarily to attack prey
   Immobilize
   kill
   Digest
90% water Other 10% :
   Proteins : enzymatic & nonenzymatic.
   Polypeptides.
   All snake venom
   Facilitates spread of other toxins
Snake bites
                    Snake bites
Pharmacology of snake venom:
  Snake venoms are chemically complex
  mixtures of proteins.
     Enzymatic properties:
          Deleterious but not lethal effect.
                Phospholipases A2
                Thrombin like enzyme
     Low molecular wt. Poly-Peptides.
          More lethal: microangiopathic vascular permeability to
           P.P. & RBC’s  Hypovolemia

Pathophysiology :
  Local & diffuse tissue damage.
     Microvascular damage
         local necrosis.
  Activation of clotting factors
         Platelet aggregation.
         DIC-like : hypofibrinogenemia +/- ↓ Platelets
              Or hypofibrinogenemia +/- Fibrinolysis
              Snake bites
Cardiovascular : 2           ry   to increased permeability & Hmg

 Hypovolemia
 Coagulopathy
 Hypotension
Release of histamine, bradykinin & other amines may contribute to
  extravascular fluid extravasation.

Effects on Muscles & NMJ:
 Myonecrosis.
 NM weakness & paralysis
              Snake bites
No true categorization:
   Cardiotoxins
   Neurotoxins
   Myotoxins
   Hemotoxins
Multiple receptor sites most deleterious
effects being:
     Nervous system.
     Renal system
                Snake bites
Envenomation syndromes:
   Terror !!! Autonomic changes without envenomation.
   Depends on amount & protein content of venom AND site.
        Pain & edema. Within minutes
        Fang marks.
        Metallic taste.
        perioral paresthesia
        Nausea & vomiting
        Tingling of toes & fingers
        Lethargy & weakness
               Snake bites
Envenomation syndromes:
   Elapidae & Hydrophidae venom is primarily
    Neurotoxic  Curare-like effects.
        Death due to respiratory depression.
   Crotalidae venom is mostly Cytolytic 
    tissue necrosis, vascular leak and
        Death due to hemorrhagic shock, ARDS or
    Signs & symptoms of
envenomation in 227 patients

   Symptoms         %

   Weakness       80

   Nausea&vomiting 70

   paresthesias   73

   Pain           60
    Signs & symptoms of
envenomation in 227 patients
 Signs              %
 Fang marks       100
 Swelling         98
 Ecchymosis       27
 fasciculations   19
 Hypotension      11
 Bullae           6
 Necrosis         4
    Signs & symptoms of
envenomation in 227 patients
 Abnormal labs         %
 ↓ fibrinogen      35
 Increased FDP’s   39
 Prolonged PT      15
 Proteinuria       9
 Hematuria         8
       Snake bites
 Snakes vs. others
 Identify the snake:
   Venomous or Nonvenomous?
   Snakes can bite even when killed!!!
  The Coral snake “Elapidae”
“red on yellow kill a fellow..red on black venom lack”
  The Coral snake “Elapidae”
“red on yellow kill a fellow..red on black venom lack”
Crotalidae Pit Vipers “cottonmouth”
 “small triangular head, pit between eye&nose,elliptical
Crotalidae   “Rattlesnake”
Naja Naja Arabicus   “Cobra”
Naja Naja Arabicus   “Cobra”

Management :
 Field   treatment.

 Emergency     room .

             SNAKE BITES
Field treatment:
   Move patient.
   Keep calm & warm
   Quick Transport to medical facility.
   Immobilize limb at level below heart.
   Avoid the following:
        Incision & suction of the wound.
        Tourniquets
        Cryotherapy.
        Electric shock therapy.
        Antivenin !!!
          SNAKE BITES
Emergency room:
 A,B&C
 Rapid detailed history:
     Time
     Type of snake.

     First aid measures.

     Allergies. Food & Drugs   Horse & Sheep
     Previous bites.
              SNAKE BITES
   Site of bite:
        Fangs
        Scratches
        Ecchymoses & erythema.
        Edema  measure & document         the circumference at points above
         & below . Baseline then Q 15-20 mins
        If a tourniquet was used  leave in place.
   Complete physical exam.
   Baseline labs
   Observe in ER for at least 8 hrs.
   Admit to ICU if anti venom is to be used.
         SNAKE BITES
 CBC & Platelet count AND type & X-match
 Coagulation profile:
     PT & PTT
     INR

     Fbrinogen

     FDP’s

 BUN , Creatinine , C.K.& Electrolytes.
 U/A
 severity of envenomation.
 Need for Antivenin.

 Amount of Antivenin.

Discharge after 8-24 hrs of observation.
Re-evaluate after 24 hrs.
Check & update immunization status.
      Grades of Envenomation and
    Antivenom Treatment Guidelines
Grade      Local              Systemic Labs                          Skin         Initial
           effects            effects                                test         AV dose
           None               None              Normal               No
Dry 0                                                                             None
           Confined to        None              Normal               No
Mild 1     bite area                                                              None

           Extends beyond     Mild: vomiting    Mild changes:        PHYSCIAN
Moderate   immediate bite     Metabolic taste   Thrombocytopenia     DISCRETION   5-10
           area but not all                     Hypofibrinogenemia                As needed
  2        part
                                                High CK

           Involves           Severe:           Marked:              PHYSCIAN
Severe     entire part        Shock, bleeding   Rhabdomyolysis       DISCRETION   15 or
                              CNS changes       Coagulopathies                    more as
  3                           Lethargy, RD ,                                      needed

Repeat labs after each infusion of
No controlled trials on premedications
for antivenom
It is strongly recommended to consult a
regional snake venom center if not
familiar with managing snake bites!!!
          SNAKE BITES
Pediatric considerations:
 Few comparative studies.
      Dose related toxin.
      High venom load.

      Smaller body volume.

   Assessment grading scales mostly for
         SNAKE BITES
       ICU management
Antivenin therapy: FabAV
   Clinical efficacy established.
   Risk of serum sickness and anaphylaxis ~14%
   Perform skin testing only if intending to treat with
“use 0.01-0.03 ml of horse serum supplied in the antivenin kit - supplied in a
   dilution of 1:10” Must be intradermal
Positive reaction is erythema or pseudopodia at the site of the
  injection within 30 minutes.
 Anticipate & be prepared for anaphylactic reactions!!
           SNAKE BITES
         ICU management
Route & dosage of Antivenin:
 Intravenous is most effective.
 Dose as per table.
 Children require larger doses per unit of
  body wt.
      More venom
      Less body water

      Less resistant to its effects

   Infuse over 1-2 hrs.
           SNAKE BITES
         ICU management
Antivenin kit contains:
   One vial antivenin ~ 1.5 gm sterile equine
    antisera with preservatives.
   One 10ml vial of bacteriostatic water for injection
   One vial of normal horse serum diluted 1:10 for
    skin testing.
   Package insert.
        Dissolve antivenin in the supplied water. Each vial seperately
        Dilute again in ½ N.S. prior to infusion.
           SNAKE BITES
         ICU management
   use 1:2 or 1:4 dilution
        Eg: 5 vials diluted to 50 ml then in 200 ml ½ N.S.
   Do not shake vigorously
   Tepid diluent and gentle shaking ensures slow but
    better dissolution.
   Start at a rate of 1ml/min if no reaction within 10
    mins increase rate to infuse over 1-2 hrs.
Children: start at 5-10ml/kg/hr gradually
increase to infuse over 1-2 hrs
   Closely observe U.O.P. & signs of overload.
         SNAKE BITES
       ICU management
Antivenin: cont.
   Most effective if given within 1st 4-6 hrs.
   May still be efficacious up to 72 hrs after
    envenomation esp if symptomatic. Russel et al
   Infusions till control – 8-12 vials followed by
    scheduled infusions.
Reactions to antivenin:
   Anaphylaxis                acute reaction
   Anticomplement reactions
   Serum sickness         1-4 wks later
           SNAKE BITES
         ICU management
Reactions to antivenin: cont.
   Skin test positive:
      Desensitizationsmall volumes less effect.
      Consider premedication with:
            IV Antihistamine.
            H2 blockers.
            Corticosteroids “controversial”
            Slow dilute infusions.
            Simultaneous Epinephrine infusions “in severe
           SNAKE BITES
         ICU management
   Needs antivenin to be successfully reversed.
   Unresponsive to treatment with replacement
    therapy or heparin if no antivenin was used
    “Treatment with coagulation factors or blood components adds
    more substrate for unneutralized venom increasing the levels of
    degradation products, which are also anticoagulant.”
   Platelets:
        as low as 2 000/ mm3
        as long as 4-7 days regardless of antivenin
        Plt transfusion may be not effective
   FFP and/or Cryoprecipitate if bleeding
         SNAKE BITES
       ICU management
Wound care:
   Gram –ve rods in snakes’ mouths.
   Antibiotic: Use only if significant bite or
    contamination risk.
   Place limb in functional position w padded splint
   Debridement of hemorrhagic blebs & vesicles by
    3-5th day.
   Daily cleaning & physiotherapy.
   Consider early skin grafting
           SNAKE BITES
         ICU management
   Avoid opioids:
        Risk of masking neurotoxic effects.
           SNAKE BITES
         ICU management
Compartment syndrome:
   ↑ tissue pressure in a closed fascial space:
        Compromises circulation.
        Neurological dysfunction.
   Myonecrosis 2ry to venom components.
   Local reaction vs true Compartment synd.
        ↓ Pulses , Cap refill & cyanosis.
        Pain at rest & movement.
   Compartment pressure > 30 mm Hg +/- ↑ CPK
        Treat with:
              Elevation.
              Additional 4-6 vials of antivenin over 1 hr.
           SNAKE BITES
         ICU management
 Hypotension increases risk of tissue
  ischemia at less pressures.
 Fasciotomy can be deleterious:
      Prolong healing.
      Scars & contractures.

      Loss of function

   Mannitol with antivenin…?
                                          snake envenomation syndromes
                                     "Modified" National Guard Health Affair
                                                                          suspected snake bite

                                                   snake brought                                                                              snake not poisonous
                                               identified as poisonous                                                                           no fang marks
                                                           or                                                                                   observe 4-8 hrs
                                                  clear fang marks

                                                    did you notice                                                                          Any clinical manifestation?
                                               clinical manifestation?

                    NO                                                                   YES
         Give anti-tetanus toxoid.                                       Determine if snake is HEMOTOXIC or
            Observe for 24 hrs                                                      NEUROTOXIC
 Did you notice any clinical manifestation?

   NO                               Yes                              HEMOTOXIC                       NEUROTOXIC                              give anti-tetanic serum
Discharge                        Hemotoxic ?                  Give polyvalent antivenom             assist respiration                              Give TT
                                 Neurotoxic?                5X10 in 250NS over 30-60 mins        sever neurological sym?                          DISCHARGE
                                                             children same dose as adults              Tensilon test

                                                                              Bivalent antivenom available?       No Bivalent antitoxin
                                                                                 give 5X10 in 250ml NS        Give double dose Polyvalent
                                                                                     over 30-60 mins                use as Bivalent
                                                                                     repeat Q 4-6 hrs
Part II Scorpion stings
       Scorpion stings
Scorpions are widely distributed in Saudi
Fourteen species or subspecies, belonging to
two families, the Buthidae and the
Nine of these around Riyadh area.
The two most venomous species appear to
be Leiurus quinquestriatus and Androctonus
crassicauda of the family Buthidae.
      Scorpion stings
Scorpions grasp prey with pincers.
Arch their tails over body.
Deliver venom by their stingers.
Injecting venom from glands lateral to
tip of stingers.
Venom composition is complex.
      Scorpion stings
scorpion stings may result in significant
morbidity and even mortality.
Most important effects:
 Neuromuscular.
 Neuroautonomic.

 Local tissue effects.
        Scorpion stings
Scorpion venom is a powerful stimulant of the
autonomic nervous system.
Venom contains:
   Hyaluridinase
   Serotonin
   Histamine releasers.
   Neurotoxins.
       It's effect has been described as a
          "sympathetic storm".
           Scorpion stings
     action through stimulation of the postganglionic
      elements of both components of the autonomic
      system and the adrenal gland with significant
      catecholamine release.
     sympathetic action and a reflex mechanism
      through the carotid sinus or carotid body.
     stimulant effect on the heart.
        Scorpion stings
Alpha receptors stimulation by the toxin plays
a major role:
   Hypertension.
   Tachycardia.
   myocardial dysfunction.
   pulmonary edema and cool extremities.
Excess catecholamines cause accumulation
of endothelins and vasoconstriction.
          Scorpion stings
Unopposed effects of alpha receptors
 suppression of insulin secretion.
 Hyperglycemia.

 Hyperkalemia.

 Accumulation of Free fatty acids and free
       Acute Myocarditis.
The overall effect of severe scorpion
envenomation is to cause:
 Hypertension.
 Increased myocardial contractility

 Dysrhythmias

 Neuromuscular hyperactivity
Severe envenomation:
 6-8 hrs
 Left cardiac failure.

 Pulmonary edema.
Autonomic disturbances:
   Agitation , irritability.
   Salivation & blurred vision.
   Tremulousness and Nystagmus.
   HTN , Tachycardia and Tachypnea
Electrolyte disturbances:
   hyper-glycemia.
   Hypocalcemia
   Hypophosphatemia.
   Increased serum Al. Phos. & S. proteins.
                              Guidelines for management of Scorpion stings
                                "Modified" National Guard Health Affairs

                                               Confirmed scorpion sting

                CHILDREN                                                        ADULTS

     At the onset of systemic reactions                                any systemic manifestations?

       Polyvalent scorpion antivenom                         NO                                           YES
             5X1ml ampoules                           OBSERVE for 8hrs                            Labs procedures:
        diluted in 20-50 ml 1/2 NS               any systemic manifestations?                  some or all maybe present
            IV over 20 minutes                                                                          if YES

repeat same dose if systemic manifestiations                NO                              GIVE SCORPION ANTIVENOM
                 persists                               DISCHARGE
                 Q 2 hrs
              max 4 doses
   Laboratory results
some or all can be seen in scorpion sting
WBC             ↑      Na + & Ca++ ↓
Blood glucose   ↑      K+         ↑
CPK              ↑     ABG    acidosis
LDH             ↑      ECG changes
Amylase         ↑      CXR changes
         Scorpion stings
Adjunctive therapy:
   Severe pain: 0.5mls of 1% xylocaine at site of
   Vomiting: Chlorepromazine 0.5-1mg/kg IM
   Convulsions: IV Diazepam slowly.
   Hypertension: Nifedipine or Hydralazine
   Pulmonary edema: Oxygen, Lasix and fluid
   Hyperthermia: Acetominophen supp
        Scorpion stings
Adjunctive therapy : cont.
 Acidosis: correct blood gases &
 shock.:
     CVP line use 1/2 NS keep 8-10 H2O
     Maintain BP & Perfusion

     Systolic BP 60-70 in children
Scorpion stings
     DON’T USE

  Barbiturates.
  Morphine

  Pethidine

  Beta blockers
     Scorpion stings
Symptoms resolve by 24-48 hrs.
Severe envenomations:
 ICU admissions & antivenin.
 Multisystem organ failure.

 Death.
         Scorpion stings
Research points:
   Use of insulin-glucose infusions for
    scorpion envenomation syndrome.

 K. R. KRISHNA MURTHY - Department of Physiology, Journal of venomous
                         animals & toxins 2000

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