Snakebite

Question 1

True or false

crotaline snakes are called pit vipers because of bilateral depressions or pits located midway between and below the level of the eye and the nostril

Answer 1

True

Question 2

True or false

pit is a heat receptor that guides strikes at warm-blooded prey or predators

Answer 2

True

Question 3

True or false

Crotaline snakes are also distinguished by the presence of two fangs that fold against the roof of the mouth, in contrast to the coral snakes, which have shorter, fixed, erect fangs.

Answer 3

True

Question 4

True or false

25% of crotaline snakebites are dry bites: venom effects do not develop

Answer 4

True

Question 5

Label the arrows

Answer 5

Question 6

diagnosis of snakebite is based on the ____________ and _________________

Answer 6

presence of fang marks

and

a history consistent with exposure to a snake

Question 7

Snake envenomation involves the presence of a snakebite plus evidence of tissue injury. Clinically, the injury may be manifest in three ways:

Answer 7

1. local injury (swelling, pain, ecchymosis),
2. hematologic abnormality (thrombocytopenia, elevated prothrombin time, hypofibrinogenemia), or
3. systemic effects (e.g., oral swelling or paresthesias, metallic or rubbery taste in the mouth, hypotension, tachycardia).

Question 8

True or false

Avoid dangerous first aid treatments such as suction and incision.

Answer 8

True

Question 9

True or false

Ice water immersion worsens the venom injury.

Answer 9

True

Question 10

True or false

Do not use tourniquets because they obstruct arterial flow and cause ischemia

Answer 10

True

Question 11

Constriction bands may be useful, especially when immediate medical care is not available. What are they?

Answer 11

A constriction band is an elastic bandage or Penrose drain, thick rope, or piece of clothing wrapped circumferentially above the bite and applied with enough tension to restrict superficial venous and lymphatic flow while maintaining distal pulses and capillary filling.

Apply the band snugly but loose enough to avoid arterial compromise. It should be easy to insert one or two fingers under the band. A constriction band can delay venom absorption without causing increased swelling

Question 12

a pressure immobilization bandage is what?

Answer 12

a compression pad placed over the bite site combined with a snug elastic bandage wrap and extremity immobilization.

This technique is recommended for coral snake and other elapid snake bites but is generally discouraged for crotaline bites because it may increase pain at the site.

Question 13

What to do in the prehospital management in Crotaline/ Pit Viper Bites?

Answer 13

In the prehospital phase,

1. immobilize the limb
2. establish IV access in another limb
3. administer oxygen
4. transport the victim to a medical facility
5. Do not remove tourniquets or constricting bands until antivenom is available, except where there is clear arterial vascular compromise threatening limb viability; in this latter situation,
6. anticipate possible rapid development of systemic envenomation upon removal of first aid
7. Institute advanced life support measures as indicated.
8. If the patient is hypotensive, rapidly administer IV isotonic fluids.
9. Immobilize the limb in a neutral position during transport to reduce further venom absorption.
10. Consult with a physician or poison control center familiar with the management of snake envenomation.

Question 14

the mainstay of therapy for venomous snakebite

Answer 14

Antivenom

Question 15

All snakebite patients who develop progressive signs and symptoms should be treated promptly with antivenom. Progression is defined as

Answer 15

worsening of local injury (e.g., pain, ecchymosis, swelling),

abnormal laboratory results (e.g., worsening platelet count, prolonged coagulation times, decreased fibrinogen level), or

systemic manifestations (e.g., unstable vital signs, abnormal mental status)

Question 16

What is the difference in clinical findings of Crotaline vs coral vs elapid snakes?

Answer 16

Question 17

Recommended First Aid Measures for Snakebite

Answer 17

Question 18

Management of Compartment Syndrome Caused by Crotalinae Snake Envenomation

Answer 18

Question 19

True or false

All coral snakes are brightly colored with black, red, and yellow rings. The red and yellow rings touch in coral snakes, but they are separated by black rings in nonvenomous snakes

Answer 19

True

“Red on yellow, kill a fellow; red on black, venom lack.”

This rule is not always true outside of the United States.

Question 20

a very painful acute corneal injury rendering the victim temporarily blind, but systemic envenomation does not occur

Answer 20

venom spit ophthalmia

Question 21

True or false

Elapid bites produce systemic effects, particularly neurologic effects: tremor, salivation, dysarthria, diplopia, bulbar paralysis with ptosis, fixed and constricted pupils, dysphagia, dyspnea, and seizure

Answer 21

True

Question 22

In Australia, the most common cause of snakebite fatality is a _______________, inadequately resuscitated, as a result of a brown snake (Pseudonaja spp.) bit

Answer 22

prehospital cardiac arrest

Question 23

True or false

True or False

Laboratory tests often determine if the patient requires antivenom treatment.

Key tests include prothrombin time (PT), INR, activated PTT, d-dimer, fibrinogen, fibrin degradation products, hemoglobin, platelet count, electrolytes, renal function test, and creatine kinase. These tests should be performed prior to removal of first aid, 1 hour after removal of first aid, and at 6 and 12 hours after bite (earlier if clinical abnormalities develop).

Answer 23

True

Question 24

What to look for in Elapid snake bite laboratory tests:

Answer 24

Look for evidence of

1. procoagulant coagulopathy (prolonged PT and activated PTT, high INR, raised d-dimer/fibrin degradation products, low fibrinogen)
2. anticoagulant coagulopathy (abnormal PT and activated PTT with high INR, but normal fibrinogen and d-dimer/fibrin degradation products)
3. platelet effects
4. rhabdomyolysis (grossly elevated creatine kinase, myo- globinuria)
5. renal damage (abnormal renal function tests, reduced urine output)
6. hyponatremia, and a
7. syndrome similar to hemolytic-uremic syndrome (thrombocytopenia, anemia, intravascular hemolysis)

Question 25

First aid management of Elapid snake bite In Australia and New Guinea:

Answer 25

1. pressure bandaging and immobilization of the involved limb are used. The principle is to contain the venom locally and prevent venom transport by lymphatic vessels. A. Wrap an elastic bandage firmly over the bite site and then extend it to cover the entire limb (bandage pressure similar to that used for sprains: firm, but not tourniquet tight). B. Limb splinting to prevent movement is an essential part of the method. Examination of lymphatic flow rates with simulated venom has demonstrated that, even if the upper or lower limb is appropriately bandaged and immobilized, walking will hasten systemic envenoming. Use of tourniquets is contraindicated. In the rare circumstance that a bite is inflicted on the trunk, apply firm pressure to the affected area without restricting breathing.

Question 26

First aid of Elapid snake bite Outside of Australia and New Guinea:

Answer 26

If the bite is from an elapid that causes predominantly local tissue damage (e.g., a spitting cobra) or an unidentified snake, then pressure bandaging and immobilization may potentially increase local tissue injury. The risk from potentially increased local tissue damage caused by pressure bandaging and immobilization must be balanced against the risk of progressive neurotoxicity, if neurotoxic snakes are present locally. Consider omitting pressure bandaging and immobiliza- tion but 1. splinting the bitten part if likely snake species do not include neurotoxic snakes.

Question 27

ED management for Elapid Snakebite

Answer 27

1. first aid and transport to a medical facility with appropriate medical expertise, laboratory facilities, and antivenom supplies. 2. Maintain pressure bandaging and immobilization (or immobilization only) until: A. envenomation is excluded B. patient can receive antivenom 3. If the patient deteriorates immediately after removal of first aid measures, reapply and give antivenom. 4. Once antivenom is infusing, remove the pressure bandage so that antivenom can reach the envenomed area.

Question 28

True or false Antivenom should be given only in cases in which there is clear clinical or laboratory evidence of systemic envenomation

Answer 28

True

Question 29

Clinical indications for immediate antivenom therapy include:

Answer 29

1. neurotoxic effects (ptosis, cranial nerve involvement, progressive muscle weakness, or diaphragmatic involvement), 2. coagulopathy 3. rhabdomyolysis 4. renal failure 5. cardiac collapse 6. significant local tissue injury 7. vomiting unresponsive to antiemetics.

Question 30

If evidence of systemic envenomation is not present, what will you do?

Answer 30

remove the first aid measures and observe the patient for at least 12 hours, or longer for some species Repeat laboratory tests 1 hour after removing the first aid measures and at intervals thereafter dictated by the patient’s condition

Question 31

True or false  Pregnancy is not a contraindication to antivenom therapy.

Answer 31

 true

Question 32

True or false In antivenom,  Give the same dose to children as adults

Answer 32

True

Question 33

True or false  In antivenom, If IV access is unavailable, consider IO administration.

Answer 33

True

Question 34

True or false IM administration is strongly discouraged due to slow absorption and potential complications of anticoagulation

Answer 34

True

Question 35

How to prepare antivenom:

Answer 35

Dilute anti- venom about 1:10 in normal saline (lower dilution in small children or cardiac-compromised adults), then commence the infusion slowly, looking for evidence of adverse reaction (rash, wheeze, hypotension, angioedema); gradually increase the rate to give the entire dose over 20 to 30 minutes (longer if high-volume antivenom). Skin testing before antivenom administration is not recommended, and equipment for treatment of anaphylaxis should be at the bedside