Unit 3: Snakebites

Question 1

Envenomation

Answer 1

when a venomous snake bites and injects venom through its fangs

Question 2

Venom

Answer 2

• differs from species to species
• complex mixture of enzymes and proteins designed to immobilize and digest prey
• immobilization occurs b/c of the neurotoxic properties of venom, causing weakness and paralysis
• can be hemotoxic (destruction of RBCs)

Question 3

Clinical Manifestations

Answer 3

• local swelling and ecchymosis (bruising)
• fang marks, teeth marks, and/or scratches visible
• with envenomation, edema and erythema at site and surrounding tissues; occurs within 30 to 60 minutes
• ecchymosis (bruising) appears around the site within 3 to 6 hours in moderate or severe envenomation
• within 8 hours, serous and/or hemorrhagic bullae appear at site
• with rattlesnake bites, necrosis around site is common

Question 4

Systemic Effects of Venom

Answer 4

• damage at the cellular level, weakening vascular walls, causing muscle breakdown, and initiating the coagulation cascade; results in excessive clotting abnormalities similar to DIC
• the toxic systemic effects can be seen in the lungs, kidneys, myocardium, peritoneum, and CNS
• thrombocytopenia (low platelets) in rattlesnake bites

Question 5

Coagulopathies that may occur

Answer 5

• cause more bleeding
• patients can hemorrhage from the bite site, mucous membranes, and venipuncture sites
• epistaxis (bloody nose)
• hematemesis (bloody emesis/vomit)
• hematuria (blood in urine)
• gingival bleeding (gums)
• hematochezia (blood in stool)
• later, hypovolemia occurs while blood loss continues, and fluid pools into the microcirculation as a result of increased capillary permeability

Question 6

Connection Check: The nurse is caring for a patient bitten by a rattlesnake 3 hours before admission to the ED. The nurse correlates which of the following clinical manifestations with a venomous snakebite?
A. Edema at the site
B. Bleeding at the site
C. Excessive diuresis
D. Dysrhythmias
E. Numbness at the site

Answer 6

A. Edema at the site

B. Bleeding at the site

Question 7

Laboratory Tests for Snake Bites

Answer 7

• CBC: to evaluate hemoglobin, hematocrit, and platelet values
• Urinalysis: testing for blood, myoglobin, and protein in urine
• Coagulation studies: evaluate presence of clotting abnormalities and DIC
• Renal studies: elevated BUN, and creatinine = renal failure
• Electrolytes: potassium may be elevated in renal failure
• Serum creatinine kinase (CK-MB): increases because of muscle breakdown; will be elevated in rhabdomyolysis

Question 8

Treatment

Answer 8

• patient’s who do not show immediate signs of envenomation should be observed for 12 hours; if does not show local or systemic signs after 12 hours, discharge home
• for severe envenomation, antivenin
• prior to administration, consultation with a medical toxicologist through the poison control center should be performed
• wound should be cleansed
• receive tetanus prophylaxis if immunization outdated or unknown
• no need for antibiotics unless wound is heavily contaminated
• do not apply a tourniquet, ice, or alcohol to the affected extremity

Question 9

Antivenin

Answer 9

• most effective when given 4 to 6 hours after envenomation
• the tissue swelling and ecchymosis around the bite site should be evaluated to determine the appropriate dose
• the adequacy of the dose is based on improvement of vital signs; decrease in tachycardia and tachypnea and a increase in BP
• partial or complete reversal of the coagulopathies
• improvement of systemic findings; diarrhea, vomiting, pain, altered mental status, or oral paresthesias

Question 10

Complications of Antivenin: Hypersensitivity

Answer 10

• reactions can occur; acute hypersensitivity
• infusions should be stopped immediately
• Epinephrine (0.3 to 0.5 mg intramuscularly), diphenhydramine, inhaled albuterol, and IV corticosteroids should be available to treat anaphylactic reaction
• antivenin may be restarted at a lower infusion rate after reaction treated
• continually monitored in ICU for 24 hours after administration of antivenin to observe for signs of immediate or recurrent toxicity

Question 11

Nursing Management: Assessment and Analysis

Answer 11

• a Crotalinae bite w/ envenomation produces swelling, pain, blistering, and ecchymosis d/t proteins in venom breaking down muscle and blood vessels and triggering the clotting cascade
• later manifestations: signs of ventilatory decompensation, rhabdomyolysis, compartment syndrome, and signs of coagulopathies (bleeding from wound, IV sites, and mucous membranes)
• muscular weakness, ptosis (drooping eye), and dysphagia

Question 12

Nursing Assessments for Sake bites

Answer 12

• Vital Signs
• Pulse oximetry
• Skin assessment
• Lab assessment: renal studies, coagulation studies, urinalysis, electrolytes (potassium)

Question 13

Assessment: Vital Signs

Answer 13

• tachycardia, hypotension, and tachypnea may be present w/ fluid volume loss d/t bleeding and increased capillary permeability causing leakage into the tissues
• worsening vital signs indicate either worsening of systemic reaction, anaphylaxis to antivenin, or needing a higher dose of antivenin
• adequacy of the antivenin dose is based on improvement of vital signs

Question 14

Assessment: Pulse Oximetry

Answer 14

-decreased O2 saturation and increases in respiratory distress may indicate a venomous coral snake bite

Question 15

Assessment: Skin Assessment

Answer 15

-venomous bite produces edema, bleeding, ecchymosis, and pain at the site

Question 16

Assessment: Renal Studies

Answer 16

-BUN and Creatinine are elevated in renal failure which is a risk w/ rhabdomyolysis

Question 17

Assessment: Coagulation studies

Answer 17

-coagulation studies will be prolonged

Question 18

Assessment: Urinalysis

Answer 18

reveals myoglobin, indicating presence of rhabdomyolysis

Question 19

Assessment: Electrolytes (potassium)

Answer 19

potassium may become elevated w/ decreased renal function

Question 20

Nursing Actions

Answer 20

• Continuous cardiac monitoring
• Administer IV fluids as ordered
• Administer Antivenin as ordered
• Keep affected extremity immobilized and in a functional position below the level of the heart
• Remove tight clothing and jewelry from affected extremity
• Keep patient calm

Question 21

Actions: Continuous cardiac monitoring

Answer 21

dysrythmias may be present with elevated potassium in renal failur

Question 22

Actions: Administer IV fluids as ordered

Answer 22

• help maintain intravascular volume, preventing hypotension

- treatment of rhabdomyolysis involves administration of IV fluids to flush the kidneys and maintain urine output

Question 23

Actions: Administer Antivenin as ordered

Answer 23

recommended tx to counteract the neurotoxic and hemotoxic effects of venom

Question 24

Actions: Keep affected extremity immobilized in a functional position below the level of the heart

Answer 24

-reduces blood flow to the heart and the spread of venom

Question 25

Actions: remove tight clothing and jewelry from affected extremity

Answer 25

these objects can act as tourniquets if swelling is present

Question 26

Discharge Instructions

Answer 26

return to ED immediately if they develop swelling, redness, increase in pain, epistaxis, fever, dark or bloody urine, SOB, vomiting, diaphoresis, any change in mental status, or any other symptoms besides mild pain at the site

Question 27

Snake Bite Prevention

Answer 27

• avoid handling snakes, including dead snakes
• when possible, avoid tall grass, piles of wood, piles of rock, and other snake hiding places
• while outdoors in the warmer months when snakes are most active, wear long pants and thick or leather boots and be aware of where they are placing their feet and hands at all times

Question 28

Evaluating Care Outcomes

Answer 28

• careful, ongoing assessment, prompt tx with antivenin, and IV fluid as dictated by patient presentation
• well-managed patient remains calm and is discharged with stable vital signs and the knowledge of when to return to the hospital if conditions change