IMMEDIATE FIRST AID
for bites by
In the event of an actual or probable bite from a Forest Cobra, execute the following first aid measures without delay.
- Make sure that the responsible snake or snakes have been appropriately and safely contained, and are out of danger of inflicting any additional bites.
- Immediately call for transportation.
- Keep the victim calm and reassured. Allow him or her to lie flat and avoid as much movement as possible. If possible, allow the bitten limb to rest at a level lower than the victim's heart.
- Immediately wrap a large crepe bandage snugly around the bitten limb starting at the site of the bite and working proximally up the limb (the full length if possible). The bandage should be as tight as one might bind a sprained ankle. (See attached copy from "First Aid for Snakebite", by Dr. S.K. Sutherland.)
- Secure the splint to the bandaged limb to keep the limb as rigid and unmoving as possible. Avoid bending or moving the limb excessively while applying the splint.
- DO NOT remove the splint or bandages until the victim has reached the hospital and is receiving Antivenom.
- Have the South African Institute for Medical Research S.A.I.M.R.) Polyvalent Antivenom ready for the emergency crew to take with the victim to the hospital. Give them the following:
- the available antivenom (at least 10 - 20 vials)
- the accompanying instruction (Protocol) packet
- the victim's medical packet (if available)
DO NOT cut or incise the bite site
DO NOT apply ice to the bite site
Summary for Human Bite
The bite of the Forest Cobra with envenomation can be rapidly fatal (possibly as early as 30 to 120 minutes). Please read the attached Medical Management Protocol and respond appropriately.
- First Aid:
- Bandage and Immobilize the bitten limb with crepe bandages and splint as described in the Immediate First Aid section. Rest this extremity below the level of the patient's heart (if practical).
- Transport to a medical center emergency or trauma service.
- Medical Management:
- Call your local Poison Control Center or the San Diego Regional Poison Control Center (800 876-4766). They should locate a consultant to help you treat this patient.
- Observe for Signs and Symptoms of Envenomation.
- If signs or symptoms are present, perform the following:
- Administer Lactated Ringers Solution at 200 to 250 mls per hour.
- Draw samples and collect initial laboratory data.
- Withdraw the contents of 3 vials of South African Institute for Medical research (S.A.I.M.R.) Polyvalent Antivenom. Administer the antivenom I.V. piggyback at a rate of 1 vial (10 mls) per minute.
- Remove the splints and crepe bandage slowly over a period of 10 minutes. If symptoms progress rapidly, reapply the bandage, and administer an additional 3 vials. Again attempt to remove the bandage.
- Allergic or untoward reactions to the antivenom should be treated with Corticosteroids, Epinephrine, Benadryl, Atarax and/or Antihistamines as appropriate.
- Monitor Signs, Symptoms, and Laboratory data, and administer additional antivenom in 1 vial increments at a rate of 1 vial (10 mls) per 5 minutes as necessary to control the progression of symptoms.
- The required amount of antivenom will vary with the severity of envenomation. One should anticipate using (including the initial dose):
4-6 vials total for a minor bite with envenomation.
8-10 vials or more may be necessary for moderate or severe bites.
for bites by
This person has received a bite and probable envenomation from a Forest Cobra (Naja melanoleuca). This is a large, thick-bodied, black snake from the tropical and subtropical rain forests of Western, Central, Eastern and Southern Africa. Considered by some to be the least dangerous of the African (Naja) Cobras, the bite of this snake, however, can be rapidly fatal without prompt intervention. In this particular species, envenomation usually presents predominately with systemic neurologic manifestations. Drowsiness, neurological and neuromuscular symptoms may develop early; paralysis, ventilatory failure or death could ensue rapidly.
Please read and execute the following procedures without delay.
- A crepe bandage and splint have been applied asimmediate first aid adjuncts to retard the absorption of the venom. DO NOT remove until the patient has arrived at the hospital and is receiving the antivenom.
- Make sure that at least 10 vials of South African Institute for Medical Research (S.A.I.M.R) Polyvalent Antivenom are present with the patient. This antivenom contains the appropriate fractions necessary to neutralize the components of Forest Cobra venom.
- If the patient has been envenomated, the treatment is 4 to 12 vials of intravenous antivenom. Envenomation is diagnosed by the presence of characteristic signs and symptoms. Necessary information follows and is organized in sections:
- Signs and Symptoms of Envenomation
- Medical Management
- General Considerations
- Special Considerations
Signs and Symptoms of Envenomation:
- Neurological and Neuromuscular: These signs and symptoms may manifest early, but may be delayed in onset. Not necessarily any or all of these will develop, even with severe envenomation. Monitor for these carefully from the outset, they generally develop very quickly and dramatically.
- Respiratory paralysis or Dyspnea Excessive salivation
- Sudden hearing loss (Unilateral and bilateral hearing loss have been reported)
- Sudden loss of consciousness
- Eyelid drooping (Ptosis)
- Palatal paralysis
- Glossopharyngeal paralysis or Dysphagia
- Limb paralysis
- Stumbling gait(Ataxia)
- Head drooping (Cervical muscle paresis or paralysis) Headache
- Local pain or Numbness around bite site (tends to be only mild)
- General: These symptoms typically manifest within 15 minutes to 4 hours following the bite if envenomation occurred. However, in some cases they may represent the only indication of clinical envenomation.
- Abdominal Pain
- Nausea and Vomiting
- Regional lymphadenopathy and Lymphadenalgia
- Hyperpyrexia (Fever)
- Flushing of the face
- Warm skin
- Increased Sweating
- Nephrotoxicity: Acute Renal Failure has not yet been reported in cases of Forest Cobra bites in humans. Oliguria or Anuria with possible changes in urinary composition will herald the development of renal shutdown. Dialysis is advised.
- Cardiotoxicity: Direct toxic effects on the myocardium or conducting system have not yet been reported in Forest Cobra envenomation. However, effects on the nervous or vascular systems may manifest as cardiac complications. Monitoring of cardiac function and rhythm is advised.
- Local Symptoms: Swelling around the area of the bite site should be expected especially of involved digits. Local necrosis with tissue slough may also be possible.
- Fang Marks: Fang marks may be present as one or more well defined punctures, as a series of small lacerations or scratches, or there may not be any noticeable or obvious markings where the bite occurred. The absence of fang marks does not preclude the possibility of a bite (especially if a juvenile snake is involved). Larger specimens of the Forest Cobra will leave large, definitive marks. Multiple bites inflicted by a single snake or by more than one snake are clearly possible, and should be noted if present (See Special Considerations below). The presence of fang marks does not always imply that the injection or deposition of venom into the bite wound (envenomation) actually occurred.
- Admit patient to an emergency or trauma service and call the consultant identified by the Poison Control Center.
- Begin a peripheral intravenous infusion (16 gauge catheter) of Lactated Ringers Solution at a rate of 250 cc/hour.
- Draw blood from the contralateral arm,and collect urine for the following laboratory tests. Mark STAT.
- Type and Cross Match TWO units of Whole blood.
- CBC with differential and platelets.
- Coagulation Parameters:
- Prothrombin Time (PT)
- Partial Thromboplastin Time (PTT)
- Fibrinogen levels
- Fibrin Degradation Products
- Serum Electrolytes, BUN/Creatinine, Calcium, Phosphorus.
- Lactate Dehydrogenase (with Isoenzyme analysis). Isoenzyme analysis may indicate multiple targets of the venom components which may dictate further management.
- Urinalysis (Macroscopic and Microscopic Analysis). Must include analysis for:
- Urine Electrolytes and Creatinine
- Free Protein
- Electrocardiogram (Place the patient on continuous monitoring).
- Continuous Urine Output Monitoring (Indwelling Foley Catheter if unconscious). Watch for possible oliguria or anuria.
- Additional Tests as needed or indicated by patient's hospital course.
- It may be necessary or practical to repeat some of the above serum and urine tests periodically over the hospital course to monitor the effects of antivenom therapy or to detect late changes in parametric values previously normal or slightly abnorma.
- OBSERVE PATIENT CLOSELY for signs and symptoms of envenomation which usually manifest between 15 minutes and two hours after the bite occurred.
- If NONE of the signs or symptoms have been noted after TWO hours, there is the possibility that the patient received a dry bite (no venom injected).
- VERY SLOWLY begin to remove the bandages and splint watching carefully for any changes in the patient's status. If any changes occur, assume the patient has been envenomed and prepare to give antivenom immediately (as directed below).
- If signs and symptoms still fail to manifest, continue CLOSE observation of the patient for an additional 12 to 24 hours.
- IF ANY SIGN OR SYMPTOM becomes apparent or has been noted during the course of treatment, begin Antivenom Therapy as follows:
- Each vial of S.A.I.M.R. Polyvalent Antivenom is packaged as a pepsin-digested purified liquid form, and is ready for immediate use.
- Secure Three vials (30 mls) immediately, and withdraw the contents into a single syringe.
- Prepare a second syringe with 500 mg of Solumedrol; place on standby.
- Administer the undiluted Antivenom by direct intravenous injection in an established I.V. slowly over a period of 2 minutes.
- Should any signs of ALLERGY/ANAPHYLAXIS (e.g., coughing, dyspnea, urticaria, itching, increased oral secretions, etc.) develop, immediately discontinue the administration of antivenom, and treat symptoms with Epinephrine, Steroids and Antihistamines. After the patient is stabilized, continue injecting the remaining initial dose of antivenom without further delay.
- After the first three vials (30 mls) of antivenom has been administered, the splint and the bandages may be removed. This should be done VERY SLOWLY over a period of FIVE minutes to prevent a bolus release of venom. If the patient's condition WORSENS:
- Reapply the crepe bandage.
- Prepare an additional three vials of antivenom immediately as directed above.
- Deliver this dose by direct intravenous injection slowly over 4 minutes.
- Release the bandage again slowly over 10 minutes.
- The patient should have received a total of 6 vials (60 mls) of antivenom at this point.
- Antivenom Therapy is the mainstay of treatment for African cobra envenomation. Many of the symptoms are ameliorated or entirely eliminated by the antivenom alone. Other symptoms will require additional modalities of therapy to correct. Local symptoms may take several days to weeks to completely resolve; their progression, however, may be controlled with antivenom therapy.
- Neurological Symptoms (especially respiratory obstruction or failure) will tend to predominate the clinical picture in cases of African cobra envenomation, and are usually the most immediate cause of dangerous problems. Often, these are improved by the antivenom. If breathing becomes impaired, provide respiratory assistance. Secretions may become copious, necessitating suctioning.
- Hematological symptoms may present as a Disseminated Intravascular Coagulopathy, and are treated as are other DICs. This has not been reported in Forest Cobra envenomations. However, spontaneous hemorrhage, prolonged clot lysis with failure of clot retraction secondary to a platelet defect, delayed rise in fibrin degradation products, and complement (C3) depletion have been seen following bites from the Spitting Cobra (Naja nigricollis).
- Renal symptoms have not yet been reported in Forest Cobra envenomation, but may complicate the situation, and if severe (i.e., Acute Renal Failure) may necessitate Peritoneal Dialysis.
- If severe muscle or respiratory paralysis develops and persists, administer 0.6 mg of Atropine IV. Follow by giving 0.5 mg of Neostigmine IV every 30 minutes for a maximum of FIVE doses.
- It is important to keep venom neutralization current and continuous. The best method to accomplish this is to keep a close watch on the patient's status. If the present condition does not improve, or should it worsen for any reason, additional antivenom should be administered. The antivenom should ideally be diluted (1:10) in Lactated Ringers Solution, and always given by intravenous infusion at a rate of ONE vial per 10 minutes. Give all additional antivenom in unit (one vial) doses. One should anticipate using (including the initial dose):
4-6 vials total for a minor bite with envenomation.
8-10 vials or more may be necessary for moderate or severe bites.
- It is advisable to perform periodic serum and urine analyses during therapy (as outlined above).
- It is always best to keep the patient in an Intensive Care setting until free of major symptoms for 24 hours. The patient should be observed in the hospital for at least 24 hours after symptoms are stabilized.
- It is important that the patient be placed at rest, kept warm, and avoid unnecessary movement.
- The onset of dangerous Neurotoxic symptoms can be rapid and subtle. In addition, they are more rapidly reversed in their early stages than when fully developed. It may be necessary to wake the patient and perform a brief neurologic check every hour or so to assure that breathing and other vital functions are not impaired. Carefully note the progress of any paralysis which may be present.
- Respiratory obstruction and failure are the greatest immediate concerns. Should the patient develop difficulties in breathing or airway impairment, respiratory support will be required. If the tongue, jaw or pharynx become paralyzed, insert an oral airway. Make sure adequate suction equipment is available and operative.
- Fluid management is very important in snake bite cases. The patient should be well hydrated, and a brisk urine output maintained. Blood replacement SHOULD NOT be started until the circulating venom anticoagulants have been fully neutralized.
- If any signs of Oropharyngeal paralysis or impaired swallowing exist, give NOTHING BY MOUTH, and keep patient on his side with head down. Watch for airway compromise and aspiration.
- Morphine is CONTRAINDICATED because of its tendency to suppress respiration. Alcohol should also be avoided.
- In cases in which Circulatory Shock remains uncorrected by antivenom therapy, Plasma volume expanders and/or vasopressor agents may be given with appropriate considerations.
- Tetanus prophylaxis should be current.
- Multiple Bites:
- It is possible for a Forest Cobra to deliver more than one bite in a single attack, and thus may inject a larger volume of venom. If there is evidence that such an attack occurred (i.e., history or multiple bite sites), the INITIAL dose of antivenom should be 6 vials (60 mls) given: by direct intravenous injection. Give the antivenom slowly over four minutes. WATCH CLOSELY for signs of allergic response; correct reaction (as described below). Give all subsequent doses in ONE vial increments at 1 vial per 10 minutes as necessitated by the presence of continued signs and symptoms.
- Severe Envenomation:
- If the patient shows severe signs of envenomation, particularly if early after the bite, up to 12 vials (120 mls) can be given as an INITIAL dose. Give the antivenom by direct intravenous injection in two divided six vial (60 mls) boluses. Correct any adverse or allergic reactions with Corticosteroids, Antihistamines and/or Epinephrine as indicated
- Testing for Equine Protein Sensitivity:
- It is NOT ADVISABLE to utilize subcutaneous or intradermal testing for sensitivity to equine products in that such testing may be unreliable, and may unnecessarily delay antivenom therapy which must be used if any signs of Forest Cobra envenomation are present.
- If there is reason to believe that the patient may be sensitive to equine protein products (e.g., previous snake bite treated with antivenom in which a sensitivity reaction was noted, multiple previous snake bites):
- If there is reason to believe that the patient may be sensitive to equine protein products, the following may be performed:
- Administer 1 gram of Solumedrol I.V. push.
- Wait 10 minutes.
- Administer the antivenom by direct intravenous infusion at a rate of 1 vial (10 mls) per 5 minutes.
- Monitor Pulse and Blood Pressure carefully. Be prepared to treat for Anaphylaxis with Epinephrine and other vasoactive medications.
- Clinical Experience with Naja melanoleuca:
- The Forest Cobra is one of the least frequent causes of snake bite among the African Cobras, largely due its forest-dwelling habits and its shy, retiring demeanor. Although one of the largest of the African Naja Cobras, the venom is considered less toxic than the others. If the snake becomes cornered or is agitated, it can quickly attack the aggressor, and if a large amount of venom is injected, a rapidly fatal outcome is possible. The Forest Cobra does not normally spit or spray its venom. The Forest Cobra is also felt by many her- petologists to be one of the most intelligent of the African elapids.
- Clinical experience with Naja melanoleuca has been very sparse, and few recorded bites have been documented. Deaths from respiratory failure have been reported, but most victims will survive, especially if prompt administration of antivenom is undertaken as soon as clinical signs of envenomation have been noted. Spontaneous recoveries without the use of specific antivenom have also been seen, however neglecting the use of antivenom places the patient at increased risk for major morbidity and mortality.
- Signs and Symptoms are likely to be similar to those seen in the other African cobras and mambas with ptosis, headache, sudden change in consciousness, respiratory difficulties predominating the clinical presentation. Some reports of Naja melanoleuca envenomation have recorded unilateral or bilateral hearing loss as an early symptom.
The following references are recommended for further indepth reading. This material includes case histories, guidelines and recent findings in elapid literature. These should be read only after treatment has begun, and the patient is in stable status.
- SOUTH AFRICAN INSTITUTE FOR MEDICAL RESEARCH: Anti-Snakebite Serum. (Package Insert with Antivenom), 1980.
-Recommended reading, although not specifically concerning the Forest Cobra-
- WARRELL, D.A.,GREENWOOD, B.M., DAVIDSON, N.M., OMEROD,L.D., PRENTICE, C.R.M.: Necrosis, Hemorrhage and Complement Depletion Following Bites by the Spitting Cobra (Naja nigricollis). Quart. J. Med., n.s., 45(177):1, 1976.
- STROVER, H.M.: Observations on Two Cases of Snake-bite by Naja nigricollis ss mossambica. Cent. Afr. J.Med., 19(1):12, 1973.
- BLAYLOCK, R.S., LICHTMAN, A.R.,POTGIETER, P.D.: Clinical Manifestations of Cape Cobra (Naja nivea) Bites. S. Afr. J. Med., 68:342, 1985.