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Spider Envenomation, Widow: Treatment & Medication
Updated: Jul 24, 2008
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
- Multimedia
Treatment
Prehospital Care
- Support the airway, breathing, and circulation per ACLS protocols with oxygen, monitors, and intravenous line.
- Negative pressure venom extraction devices (eg, The Extractor - Sawyer Products) have not been evaluated for treatment of widow spider envenomation.
- Electric shock and various folk and herbal remedies lack therapeutic value and are potentially harmful.
- Do not give antivenom in the field because of the risk of severe allergic complications.
- Attempts to secure the spider may be helpful in confirming widow spider envenomation.
Emergency Department Care
- Antivenom should be given for imminent risk of severe complication of envenomation (see Complications). The risk of allergy to antivenom must be weighed against the benefit of relieving prolonged discomfort, avoiding hospitalization, and preventing complications.
- Grade 1 - Mild envenomation
- Local pain at envenomation site
- Normal vital signs
- Grade 2 - Moderate envenomation
- Muscular pain in the envenomated extremity
- Extension of muscular pain to the abdomen if bitten on a lower extremity or to the chest if envenomated on an upper extremity
- Local diaphoresis of envenomation site or involved extremity
- Normal vital signs
- Grade 3 - Severe envenomation
- Generalized muscular pain in the back, abdomen, and chest
- Diaphoresis remote from envenomation site
- Abnormal vital signs (blood pressure >140/90 mm Hg, pulse >100)
- Nausea and vomiting
- Headache
Consultations
- Local poison control centers may assist management of difficult envenomations.
- The Antivenom Index, published by the American Zoo and Aquarium Association and the American Association of Poison Control Centers, lists the locations, amounts, and various types of antivenom stores.
Medication
Most widow spider envenomations may be managed with opioid analgesics and sedative-hypnotics. Antivenom may be indicated for patients who have severe envenomations with pain refractory to these measures. Antivenom should be considered when envenomation seriously threatens pregnancy or precipitates potentially limb- or life-threatening effects (eg, severe hypertension, unstable angina, priapism, compartment syndrome). On average, antivenom administration results in resolution of most symptoms one-half hour after administration, and it has been shown to decrease the need for hospitalization.
A new antivenom (Aracmyn, manufactured by Instituto Bioclon) is about to undergo phase 3 clinical trials in the United States, but it has not yet been approved for general use. It may be associated with less risk of allergic reaction than the existing antivenom, so its indications for use may differ from the current indications. Calcium gluconate is no longer recommended for widow spider envenomation. Studies suggest benzodiazepines are more efficacious than muscle relaxants for treatment of muscle pain related to widow spider envenomation. Antibiotics are not indicated.
Analgesics
Pain control is essential to quality patient care. It ensures patient comfort and promotes pulmonary toilet. Most analgesics have sedating properties that are beneficial for patients who have sustained trauma.
Morphine sulfate (Duramorph, Infumorph, Astramorph injections)
DOC for narcotic analgesia because of its reliable and predictable effects, safety profile, and ease of reversibility with naloxone. Morphine sulfate administered IV may be dosed in a number of ways and commonly is titrated to the desired effect.
Adult
2-10 mg IV/IM; titrate to relief of pain
Pediatric
0.1 mg/kg IV/IM
Phenothiazines may antagonize the analgesic effects of opiate agonists; tricyclic antidepressants, MAOIs, and other CNS depressants may potentiate adverse effects of morphine when used concurrently
Documented hypersensitivity; hypotension; potentially compromised airway with uncertain rapid airway control; hypotension; respiratory depression; constipation; urinary retention
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Avoid in hypotension, respiratory depression, nausea, emesis, constipation, and urinary retention; caution in atrial flutter and other supraventricular tachycardias; has vagolytic action and may increase ventricular response rate
Benzodiazepines
By binding to specific receptor sites, these agents appear to potentiate the effects of gamma-aminobutyrate (GABA) and to facilitate inhibitory GABA neurotransmission and other inhibitory transmitters.
Lorazepam (Ativan)
A sedative hypnotic in the benzodiazepine class that has a short onset of effect and relatively long half-life. By increasing the action of GABA, a major inhibitory neurotransmitter in the brain, it may depress all levels of the CNS, including the limbic and reticular formation.
Adult
1-2 mg IV/IM
Pediatric
0.01 mg/kg IV/IM
Toxicity of benzodiazepines in CNS increases when used concurrently with alcohol, phenothiazines, barbiturates, and MAOIs
Documented hypersensitivity; preexisting hypotension; narrow-angle glaucoma
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Caution in renal or hepatic impairment, myasthenia gravis, organic brain syndrome, or Parkinson disease
Diazepam (Valium)
Depresses all levels of CNS (eg, limbic and reticular formation), possibly by increasing activity of GABA. Third-line agent for agitation or seizures because of shorter duration of anticonvulsive effects and accumulation of active metabolites that may prolong sedation.
Adult
5-10 mg IV q10-15min until symptoms resolve; not to exceed 30 mg
Pediatric
<30 d: Not established
30 days to 5 years: 0.2-0.5 mg IV (slowly) q2-5min until symptoms resolve; not to exceed 5 mg
>5 years: 1 mg IV (slowly) q2-5min until symptoms resolve; not to exceed 10 mg
Increases toxicity of benzodiazepines in CNS with coadministration of phenothiazines, H1 blockers, barbiturates, alcohols, and MAOIs
Documented hypersensitivity, hypotension, acute narrow-angle glaucoma
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Caution with other CNS depressants, low albumin levels, or renal and hepatic disease (may increase toxicity); monitor for respiratory depression with high or repeated doses
Midazolam (Versed)
Used as alternative in termination of refractory status epilepticus. Because water soluble, takes approximately 3 times longer than diazepam to peak EEG effects. Thus, clinician must wait 2-3 min to fully evaluate sedative effects before initiating procedure or repeating dose. Has twice the affinity for benzodiazepine receptors than diazepam. May be administered IM if unable to obtain vascular access.
Adult
0.01-0.05 mg/kg (usually 0.5-4 mg, up to 10 mg) IV slowly over several min; may repeat q10-15min until adequate response achieved
Pediatric
<32 weeks: 0.5 mcg/kg/min IV infusion
>32 weeks: 1 mcg/kg/min IV infusion
Children: 0.05-0.2 mg/kg IV over 2-3 min, followed by 1-2 mcg/kg/min continuous infusion
Status epilepticus (refractory to standard therapy), > 2 months and children: 0.15 mg/kg followed by continuous infusion of 1 mcg/kg/min, titrating dose upward q5min until seizures controlled
Sedative effects may be antagonized by theophyllines; narcotics, cimetidine, ethanol, and erythromycin may accentuate sedative effects because of decreased clearance; reduce dose of thiopental by 15% when using together
Documented hypersensitivity; preexisting hypotension, narrow-angle glaucoma, and sensitivity to propylene glycol (diluent)
Pregnancy
D - Fetal risk shown in humans; use only if benefits outweigh risk to fetus
Precautions
Caution in congestive heart failure, pulmonary disease, renal impairment, hepatic failure, neuromuscular disease, hypotension, and patients >60 y; monitor for respiratory depression with high or repeated doses; consider lower dosages in patients with organic brain syndrome and patients who may have inhibition of benzodiazepine metabolism and clearance (eg, using nicotine, taking cimetidine)
Antivenom
Used to neutralize the toxin of a widow spider bite.
Antivenin Latrodectus mactans
Derived from horse serum and produced by Merck & Co., Inc. Consider for patients with grade 2 or grade 3 envenomations who are refractory to opiates and sedative-hypnotics and do not have risk factors for immediate hypersensitivity reactions. Some authorities advocate antivenom administration for certain patient groups, such as children and elderly persons. Package insert recommends skin testing for possible allergic reaction to the antivenom.
To mix the antivenom, dissolve 1 vial in 2.5 mL of sterile diluent with gentle agitation, then dilute this into a total volume of at least 20-50 mL NS. The package insert recommends intravenous injection over 15 min. However, adverse reactions may be averted by further diluting the antivenom (eg, to a total volume of 200 mL) and administering the infusion slowly (eg, over 1 h). Symptoms have been shown to improve within 1 h of antivenom administration and for as long as 48 h after envenomation. In Australia, antivenom for Latrodectus envenomation is available from Commonwealth Serum Laboratories and, in South Africa, from the South African Institute of Medical Research. Indications for antivenom use and routes of administration vary around the world.
Adult
1 vial in 50-250 mL NS; administer IV infusion at 1 mL/min over 15 min, watching for signs of allergic reaction, then complete the infusion over 1 h
Pediatric
Administer as in adults
None reported
Documented hypersensitivity; previous exposure to horse serum
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Mortality from widow spider envenomation is extremely rare, and some argue against administration of antivenom when treatment may be more dangerous than the injury; some recommend routine premedication with antihistamines (H1 and H2 blockers); black widow spider envenomation is associated with abruptio placentae and fetal demise; benefits of antivenom administration in pregnancy must be weighed against risks
Immunizations
Tetanus immunization should be instituted following a black widow spider bite. Tetanus results from elaboration of an exotoxin from Clostridium tetani. A booster injection in previously immunized individuals is recommended to prevent this potentially lethal syndrome. Patients who may not have been immunized against C tetani products (eg, immigrants, elderly persons) should receive tetanus immune globulin (Hyper-Tet).
Diphtheria-tetanus toxoid (dT)
Used for the passive immunization of any person with a wound that might be contaminated with tetanus spores.
Adult
Prophylaxis: 250-500 U IM in opposite extremity to tetanus toxoid lesion
Clinical tetanus: 3000-10,000 U IM
Pediatric
Prophylaxis: 250 U IM in opposite extremity as tetanus toxoid
Clinical tetanus: Administer as in adults
Patients receiving immunosuppressants, including corticosteroids or radiation therapy, may remain susceptible despite immunization because of poor immune response; cimetidine may enhance or augment delayed-hypersensitivity responses to skin-test antigens; avoid concurrent use of medication with systemic chloramphenicol because it may impair amnestic response to tetanus toxoid; concurrent use of tetanus immune globulin may delay development of active immunity by several days (nevertheless, interaction is clinically insignificant and does not preclude its concurrent use)
Documented hypersensitivity; a history of any type of neurological symptoms or signs following administration of this product; FDA recommends that elective tetanus immunization be deferred during any outbreak of poliomyelitis because tetanus toxoid injections are an important cause of provocative poliomyelitis
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Do not use to treat actual tetanus infections, or for immediate prophylaxis of unimmunized individuals (use tetanus antitoxin instead, preferably human tetanus immune globulin) diminished antibody response to active immunization may be observed in patients receiving immunosuppressive therapy; better to defer primary diphtheria immunization until immunosuppressive therapy discontinued; routine immunization of symptomatic and asymptomatic HIV-infected persons is recommended; persons with isolated immunoglobulin A (IgA) deficiency have potential for developing antibodies to IgA and could have anaphylactic reactions to subsequent administration of blood products that contain IgA
Do not perform skin testing since the intradermal injection of concentrated gamma globulin may cause a localized area of inflammation that can be misinterpreted as a positive allergic reaction when it actually is a localized chemical tissue irritation; true allergic responses to human gamma globulin given in the prescribed IM manner are extremely rare; do not admix with other medications because usually incompatible
Antihistamines
Prevent the histamine response in sensory nerve endings and blood vessels. More effective in preventing histamine response than in reversing it.
Antihistamines act by competitive inhibition of histamine at the H1 receptor, which mediates the wheal and flare reactions, bronchial constriction, mucous secretion, smooth muscle contraction, edema, hypotension, CNS depression, and cardiac arrhythmias.
In the treatment of black widow spider envenomations, antihistamines are used before antivenom administration to reduce acute adverse reactions to the antivenom.
Diphenhydramine (Benadryl)
Used for the symptomatic relief of allergic symptoms caused by histamine released in response to allergens.
Adult
10-50 mg IV/IM q6-8h prn; not to exceed 400 mg/d
Pediatric
5 mg/kg/d IV/IM or 150 mg/m2/d IV/IM divided qid; not to exceed 300 mg/d
Potentiates effect of CNS depressants; because of alcohol content, do not give syrup dosage form to patient taking medications that can cause disulfiramlike reactions
Documented hypersensitivity
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
May exacerbate angle-closure glaucoma, hyperthyroidism, peptic ulcer, and urinary tract obstruction
More on Spider Envenomation, Widow |
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| Differential Diagnoses & Workup: Spider Envenomation, Widow |
 Treatment & Medication: Spider Envenomation, Widow |
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| Multimedia: Spider Envenomation, Widow |
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References
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Langley RL, Morrow WE. Deaths resulting from animal attacks in the United States. Wild Environ Med. 1997;8:8-16.
Pneumatikos IA, Galiatsou E, Goe D, Kitsakos A, Nakos G, Vougiouklakis TG. Acute fatal toxic myocarditis after black widow spider envenomation. Ann Emerg Med. Jan 2003;41(1):158. [Medline].
Watson WA, Litovitz TL, Klein-Schwartz W, Rodgers GC Jr, Youniss J, Reid N, et al. 2003 annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. Sep 2004;22(5):335-404. [Medline].
Woestman R, Perkin R, Van Stralen D. The black widow: is she deadly to children?. Pediatr Emerg Care. Oct 1996;12(5):360-4. [Medline].
Bronstein AC, Spyker DA, Cantilena LR Jr, Green J, Rumack BH, Heard SE. 2006 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS). Clin Toxicol (Phila). Dec 2007;45(8):815-917. [Medline].
Hoxha R. Two Albanians die from black widow spider bites. BMJ. Aug 5 2006;333(7562):278. [Medline].
Further Reading
Keywords
black widow spider, spider bite, black widow spider bite, spider envenomation, Latrodectus, Latrodectus mactans mactans, brown widow, Latrodectus geometricus, red-legged widow, Latrodectus bishopi, redback spider, Latrodectus hasselti, button spider, Latrodectus indistinctus, Latrodectus variolus, Latrodectus hesperus, Latrodectus mactans tredecimguttatus, Latrodectus pallidus
