eMedicine Specialties > Emergency Medicine > Environmental
Snake Envenomation, Cobra: Follow-up
Updated: Dec 29, 2008
Follow-up
Further Inpatient Care
- Admit all cobra snakebite patients to closely monitored settings, whether or not antivenom is given.
- Observe asymptomatic patients for at least 24 hours. Delayed signs and symptoms may occur.
- If signs or symptoms of envenomation progress after first administration of antivenom, a second dose of antivenom may be required. If two doses of antivenom are given and the victim still requires airway intubation and ventilatory support, further antivenom administration will be unhelpful.
- Continue to administer systemic antihistamines and steroids to a patient experiencing an acute allergic reaction to antivenom until patient is stable.
- Aspirate bullae
- If necrosis occurs, initiate standard, conservative wound care (eg, cleansing, splinting, debridement as necessary).
- Secondary bacterial infections may occur and are usually caused by gram-negative bacilli, such as Proteus, Pseudomonas, and Enterobacter species. Initial antibiotics should cover gram-positive and gram-negative organisms. Culture results should determine use of further antibiotics.
- Occasionally, debridement, amputation, or grafting of tissue is required.
- Warn patients who have received antivenom about the signs and symptoms of delayed serum sickness. If these signs or symptoms develop after discharge, evaluate patient promptly for initiation of systemic steroids and diphenhydramine as outlined above.
Further Outpatient Care
- Patients with necrosis need continued outpatient management of their wounds and should be warned about the signs and symptoms of infection. Continued outpatient physical therapy may be necessary.
- Patients who received antivenom should be aware of the signs and symptoms of delayed serum sickness and should return if they develop.
- Patients who have experienced acute ophthalmia following spitting cobra venom exposure should have outpatient ophthalmologic follow-up to monitor for complications such as uveitis or corneal ulceration.
Transfer
- People bitten by cobras should be cared for in a facility capable of intensive monitoring.
Deterrence/Prevention
- Professional snake keepers should use standard safety techniques (eg, locked cages, trap boxes, protective eyewear) when dealing with cobras and other species that spit venom.
- Amateurs should refrain from keeping exotic venomous snakes in their collections. If they keep such snakes, they should know the specific species they keep, the appropriate antivenom type, and where it can be obtained in an emergency. Preferably, amateurs should maintain their own supply of appropriate antivenom, but this may be difficult (due to regulations related to importing foreign antivenoms into the country) and expensive.
- Travelers in regions where cobras are indigenous should wear protective clothing (long pants and footwear), avoid areas where snakes seek cover, and know the location of the nearest source of medical care in case they are bitten.
Complications
Complications of cobra envenomation may include the following:
- Respiratory failure/arrest
- Cardiovascular collapse
- Prolonged neuromuscular weakness
- Tissue necrosis
- Antivenom-related complications
- Anaphylactoid reactions
- Delayed serum sickness
Prognosis
- Many patients recover with no specific treatment.
- The neurotoxic effects of cobra venom are completely reversible, though recovery may take up to 6 days.
- Reports of death within 1 hour of cobra bite exist, but a timeframe of 2-6 hours is more typical of fatal cases.
- With sound supportive care (eg, prevention of aspiration) and appropriate, prompt antivenom administration, anticipate recovery from cobra envenomation.
Patient Education
- Advise amateur herpetoculturists bitten by a venomous snake in their collection to not keep such animals. If they previously have received antivenom, their risk for an allergic reaction may be increased should antivenom use be required again in the future.
- For excellent patient education resources, visit eMedicine's Bites and Stings Center. Also, see eMedicine's patient education article Snakebite.
Miscellaneous
Medicolegal Pitfalls
- Considering the potential delay in onset of signs and symptoms, do not discharge patients with a possible cobra bite until they have been observed for 24 hours.
- Acute or delayed allergic reaction associated with antivenom use is always a risk. If possible, obtain the patient's consent to administer antivenom, and be immediately available throughout administration to intervene if necessary.
- Failure to aggressively manage a patient's airway in the face of impending respiratory failure may lead to aspiration, with its attendant complications.
- Foreign-produced antivenoms for snakes not native to the United States are not FDA-approved, and some medical/legal risk may be associated with their use. Conversely, failure to use such a product in a significantly envenomed patient could put the victim at risk of a poor outcome. In such cases, prompt consultation with a snakebite expert is indicated.
Special Concerns
- Treatment of a patient with significant cobra venom poisoning and evidence of acute allergy to antivenom (positive skin test or reaction on administration of antivenom) is difficult. Weigh the risks and benefits of proceeding with antivenom. Options include the following:
- Maximally premedicate the patient with drugs that might blunt or prevent anaphylaxis (eg, H1 and H2 blockers, steroids), and begin the infusion very slowly and in a very dilute state.
- Admit the patient to an intensive care facility, establish invasive hemodynamic monitoring (arterial line), maximally premedicate the patient as above, establish an additional line with an epinephrine infusion, and administer very dilute antivenom at a slow rate. Epinephrine infusion can be titrated with the antivenom to prevent an anaphylactic reaction. This technique should be used only in consultation with an intensivist, a toxicologist, or an expert in snakebite management.
- Rely on supportive care measures only, including aggressive airway and respiratory management.
More on Snake Envenomation, Cobra |
| Overview: Snake Envenomation, Cobra |
| Differential Diagnoses & Workup: Snake Envenomation, Cobra |
| Treatment & Medication: Snake Envenomation, Cobra |
 Follow-up: Snake Envenomation, Cobra |
| Multimedia: Snake Envenomation, Cobra |
| References |
| « Previous Page | Next Page » |
References
Russell FE. Snake venom poisoning in the United States. Annu Rev Med. 1980;31:247-59. [Medline].
Bush SP, Hegewald KG, Green SM, et al. Effects of a negative pressure venom extraction device (Extractor) on local tissue injury after artificial rattlesnake envenomation in a porcine model. Wilderness Environ Med. 2000;11(3):180-8. [Medline].
Gold BS. Neostigmine for the treatment of neurotoxicity following envenomation by the Asiatic cobra. Ann Emerg Med. Jul 1996;28(1):87-9. [Medline].
Khandelwal G, Katz KD, Brooks DE, Gonzalez SM, Ulishney CD. Naja Kaouthia: two cases of Asiatic cobra envenomations. J Emerg Med. Epub 2007 Jan 17;32(2):171-4. [Full Text].
Lifshitz M, Maimon N, Livnat S. Walterinnesia aegyptia envenomation in a 22-year-old female: a case report. Toxicon. Mar 2003;41(4):535-7. [Medline].
Lim BL. Venomous land snakes of Malaysia. In: Chou LM, Gopalkrishnakone P, eds. Snakes of Medical Importance - Asia-Pacific Region. National of University of Singapore;1990:387-417.
Looareesuwan S, Viravan C, Warrell DA. Factors contributing to fatal snake bite in the rural tropics: analysis of 46 cases in Thailand. Trans R Soc Trop Med Hyg. 1988;82(6):930-4. [Medline].
Low BW, Corfield BWR. Acetylcholine receptor alpha-toxin binding site - theoretical and model studies. Asia Proc J Pharmacol. 1987;2:115-27.
Minton SA. Bites by non-native venomous snakes in the United States. Wilderness Environ Med. 1996;4:297-303.
Minton SA Jr. Paraspecific protection by elapid and sea snake antivenins. Toxicon. Jul 1967;5(1):47-55. [Medline].
Norris RL, Ngo J, Nolan K. Physicians and lay people are unable to apply pressure immobilization properly in a simulated snakebite scenario. Wilderness Environ Med. 2005;16(1):16-21. [Medline].
Reid HA. Bites by foreign venomous snakes in Britain. Br Med J. Jun 17 1978;1(6127):1598-1600. [Medline].
Reid HA. Cobra bites. Br Med J. 1964;2:540-545.
Reid HA, Thean PC, Martin WJ. Epidemiology of snake bite in north Malaya. Br Med J. 1963;1:992-997.
Sawai Y, Tseng CS. Snakebites on Taiwan. Snake. 1969;1:9-18.
Stahel E. Epidemiological aspects of snake bites on a Liberian rubber plantation. Acta Trop. Dec 1980;37(4):367-74. [Medline].
Tin-Myint, Rai-Mra, Maung-Chit, et al. Bites by the king cobra (Ophiophagus hannah) in Myanmar: successful treatment of severe neurotoxic envenoming. Q J Med. Sep 1991;80(293):751-62. [Medline].
Veto T, Price R, Silsby JF, Carter JA. Treatment of the first known case of king cobra envenomation in the United Kingdom, complicated by severe anaphylaxis. Anaesthesia. Jan 2007;62(1):75-8. [Full Text].
Viravan C, Looareesuwan S, Kosakarn W, et al. A national hospital-based survey of snakes responsible for bites in Thailand. Trans R Soc Trop Med Hyg. Jan-Feb 1992;86(1):100-6. [Medline].
Visser J, Chapman DS. Snakes and Snake-bite. 1978:1-152.
Walsh DS, Looareesuwan S, Wilairatana P, et al. Randomized dose-ranging study of the safety and efficacy of WR 238605 (Tafenoquine) in the prevention of relapse of Plasmodium vivax malaria in Thailand. J Infect Dis. Oct 1999;180(4):1282-7. [Medline].
Warrell DA. Clinical toxicology of snakebite in Africa and the Middle East and Asia. In: Clinical Toxicology of Animal Venoms and Poisons. CRC Press;1995:433-594.
Warrell DA, Ormerod LD. Snake venom ophthalmia and blindness caused by the spitting cobra (Naja nigricollis) in Nigeria. Am J Trop Med Hyg. May 1976;25(3):525-9. [Medline].
Watt G, Padre L, Tuazon L, et al. Bites by the Philippine cobra (Naja naja philippinensis): prominent neurotoxicity with minimal local signs. Am J Trop Med Hyg. Sep 1988;39(3):306-11. [Medline].
Watt G, Theakston RD, Hayes CG, et al. Positive response to edrophonium in patients with neurotoxic envenoming by cobras (Naja naja philippinensis). A placebo-controlled study. N Engl J Med. Dec 4 1986;315(23):1444-8. [Medline].
Westhoff G, Tzschatzsch K, Bleckmann H. The spitting behavior of two species of spitting cobras. J Comp Physiol A Neuroethol Sens Neural Behav Physiol. Oct 2005;191(10):873-81. [Medline].
Wongtongkam N, Wilde H, Sitthi-Amorn C. A study of Thai cobra (Naja kaouthia) bites in Thailand. Mil Med. Apr 2005;170(4):336-41. [Medline].
Further Reading
Keywords
snakebite, snake bite, cobra bite, snake venom, treatment, symptoms, cobra envenomations, snake envenomations, Naja, Naja philippinensis, Philippine cobra, Ophiophagus hannah, king cobra, Hemachatus haemachatus, ringhals, Walterinnesia aegyptia, desert black snake, Boulengerina, water cobra Pseudohaje, tree cobra
