snakebite
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Etiology
- pit vipers (Crotalidae)
- 99% of snakebite poisonings in U.S.
- Russell's viper (India)
- saw-scaled viper (India)
- coral snakes (Elapidae)
- sea snakes
- cobra (India)
- krait (India)
Epidemiology
- 8000-10,000 snakebites annually; 10-15 deaths annually U.S.
- worldwide, 65,000 deaths (2019). 81% in India[4]
- in India, cobra & krait (neurotoxic venom) & Russell's viper & saw-scaled viper (hemotoxic venom) account for 90% of deaths[4]
- neurotoxic snakes with double the case-fatality rate of hemotoxic snakes (8.8% vs 4.2%)[4]
- southeastern & gulf states have highest per capita incidence
- most snakebites occur from April to October with peak months July & August
Pathology
- hemotoxic vemom: clotting disorders estimated to occur in 40%-90%
- neurotoxic venom: respiratory failure, paralysis, vision disturbance[4]
Laboratory
- complete blood count (CBC) with differential & peripheral smear
- hemolysis
- leukocytosis (20,000-30,000/mm3)
- thrombocytopenia
- prolonged PT/PTT
- DIC panel:
- decreased plasma fibrinogen
- increased fibrin degradation products (D-dimer)
- type & screen
- serum chemistries
- increased serum urea nitrogen
- increased serum creatinine
- serum electrolyte abnormalities
- increased serum transaminases
- increased serum bilirubin
- increased serum creatine kinase
- urinalysis
Diagnostic procedures
Staging
Grading of envenomation:
- Grade 0: no envenomation: no local or systemic manifestations
- Grade 1: minimal envenomation: local pain & edema, no systemi manifestations
- Grade 2: moderate envenomation: local & mild systemic manifestations &/or positive laboratory findings
- Grade 3: severe envenomation: local, systemic & laboratory abnormalities
Complications
- long-term health effects may occur
Management
- in the field
- reassurance
- immobilization of affected extremity
- exertion will increase systemic absorbtion
- wide constriction bands may prevent lymphatic drainage without compromising blood flow
- use of tourniquets is discouraged
- incision & suction not indicated
- transport to nearest available hospital
- 2 large bore IVs
- antivenin is the only specific therapy
- IV administration
- local injection not recommended
- skin testing necessary prior to administration of antivenin
- dosage based upon clinical grading of envenomation
- additional infusions every 2 hours until signs & symptoms have resolved
- complications of treatment generally related to reactions to antivenin
- hypersensitivity with anaphylaxis may occur in as many as 25% of patients
- serum sickness in 50-75% of patients
- fever, malaise, arthralgias, lymphadenopathy, morbilliform rash in 7-14 days
- tetanus toxoid
- broad spectrum antibiotics if wound infection suspected
- snake oral flora includes gram-positive & gram-negative rods
- no role for cryotherapy or ice packs
- fasciotomy & surgical debridement
- massive necrosis or gangrene
- decompression of compartment syndrome
- ICU admission
More general terms
Additional terms
References
- ↑ Saunders Manual of Medical Practice, Rakel (ed), WB Saunders, Philadelphia, 1996, pg 1175-77
- ↑ Hussain T, Jan RA A Viper Bite. N Engl J Med 2015; 373:1059. September 10, 2015 <PubMed> PMID: https://www.ncbi.nlm.nih.gov/pubmed/26352817 <Internet> http://www.nejm.org/doi/full/10.1056/NEJMicm1410237
- ↑ Gerardo CJ, Vissoci JRN, Evans CS et al Does This Patient Have a Severe Snake Envenomation? The Rational Clinical Examination Systematic Review. JAMA Surg. Published online February 13, 2019. PMID: https://www.ncbi.nlm.nih.gov/pubmed/30758508 https://jamanetwork.com/journals/jamasurgery/fullarticle/2724359
- ↑ 4.0 4.1 4.2 4.3 4.4 4.5 Walker M World's Deadliest Neglected Disease: Snakebite Slithers Under the Radar.
Pick your poison: neurotoxic or hemotoxic. MedPage Today November 25, 2020 https://www.medpagetoday.com/infectiousdisease/publichealth/89905