Unit 3: Snakebites Flashcards
Envenomation
when a venomous snake bites and injects venom through its fangs
Venom
- 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)
Clinical Manifestations
- 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
Systemic Effects of Venom
- 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
Coagulopathies that may occur
- 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
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
A. Edema at the site
B. Bleeding at the site
Laboratory Tests for Snake Bites
- 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
Treatment
- 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
Antivenin
- 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
Complications of Antivenin: Hypersensitivity
- 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
Nursing Management: Assessment and Analysis
- 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
Nursing Assessments for Sake bites
- Vital Signs
- Pulse oximetry
- Skin assessment
- Lab assessment: renal studies, coagulation studies, urinalysis, electrolytes (potassium)
Assessment: Vital Signs
- 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
Assessment: Pulse Oximetry
-decreased O2 saturation and increases in respiratory distress may indicate a venomous coral snake bite
Assessment: Skin Assessment
-venomous bite produces edema, bleeding, ecchymosis, and pain at the site
Assessment: Renal Studies
-BUN and Creatinine are elevated in renal failure which is a risk w/ rhabdomyolysis
Assessment: Coagulation studies
-coagulation studies will be prolonged
Assessment: Urinalysis
reveals myoglobin, indicating presence of rhabdomyolysis
Assessment: Electrolytes (potassium)
potassium may become elevated w/ decreased renal function
Nursing Actions
- 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
Actions: Continuous cardiac monitoring
dysrythmias may be present with elevated potassium in renal failur
Actions: Administer IV fluids as ordered
- help maintain intravascular volume, preventing hypotension
- treatment of rhabdomyolysis involves administration of IV fluids to flush the kidneys and maintain urine output
Actions: Administer Antivenin as ordered
recommended tx to counteract the neurotoxic and hemotoxic effects of venom
Actions: Keep affected extremity immobilized in a functional position below the level of the heart
-reduces blood flow to the heart and the spread of venom
Actions: remove tight clothing and jewelry from affected extremity
these objects can act as tourniquets if swelling is present
Discharge Instructions
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
Snake Bite Prevention
- 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
Evaluating Care Outcomes
- 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
