IMMEDIATE FIRST AID
for bites by
Western Green Mamba
In the event of an actual or probable bite from a Western Green Mamba, 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. Struan).
- 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 Pasteur Institute Antidendroaspis (Trivalent Mamba) 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
DO NOT apply ice to the bite site
Summary for Human Bite
Western Green Mamba
The bite of the Western Green Mamba with envenomation can be rapidly fatal (possibly as early as 30 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 4 vials of Pasteur Institute Antidendroaspis (Trivalent Mamba) 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 4 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.
8-12 vials or more may be necessary for moderate or severe bites.
for bites by
Western Green Mamba
This person has received a bite and probable envenomation from a Western Green Mamba (Dendroaspis viridis). This is an extremely venomous, rapidly moving tree dwelling snake which is distributed throughout the tropical rain forest regions of Guinea, Liberia, Senegal, Ghana, Ivory Coast and adjacent areas of western Africa. Although the Western Green Mamba is generally considered to be less dangerous and less aggressive than the Black Mamba (Dendroaspis polylepis polylepis), its bite has been responsible for human fatalities. Envenomation signifies a true medical emergency. 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 may ensue rapidly.
Please read and execute the following procedures without delay.
- A crepe bandage and splint have been applied as immediate first aid adjuncts to retard the absorption of the venom. DO NOT remove the bandage or splint until the patient has arrived at the hospital and is receiving the antivenom.
- Make sure that at least 10 vials of Pasteur Institute Trivalent Mamba Antivenom are present with the patient. This antivenom contains the appropriate fractions necessary to neutralize Western Green Mamba venom.
- If the patient has been envenomated, the treatment is 4 to 10 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 will usually manifest earliest. Not all signs and symptoms will necessarily develop, even with severe envenomation.
- Respiratory paralysis or Dyspnea
- Excessive salivation (Oral secretions may become profuse and thick)
- Sudden loss of consciousness
- Paresthesias and Dysesthesias
- Palatal paralysis
- Glossopharyngeal paralysis or Dysphagia
- Limb paralysis
- Head drooping (Cervical muscle paresis or paralysis) Headache
- Local pain or Numbness around bite site (tends to be mild)
- General: These symptoms typically manifest within thirty minutes to four hours following the bite if envenomation occurred.
- Abdominal Pain (may be severe)
- Nausea and Vomiting
- Regional lymphadenopathy and Lymphadenalgia
- Flushing of the face
- Increased Sweating
- Nephrotoxicity: Acute Renal Failure has been reported in a few cases of Black Mamba bites in humans as well as in animal models. It has not yet been reported in Western Green Mamba envenomations. Oliguria or Anuria with possible changes in urinary composition will herald the development of renal shutdown. Dialysis is advised.
- Cardiotoxicity: Changes in cardiovascular status result primarily from the effects of Circulatory Collapse and Shock, as well as vagal blockade resulting in Tachydysrhythmias. Pulse and pressure may initially be within normal limits, but may change with rapid onset cardiovascular collapse. Cardiovascular involvement is more frequently reported in Black Mamba envenomations.
- Local Symptoms: Local tissue damage following Western Green Mamba envenomation in most cases is mild with minimal edema and pain.
- 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). In general, the fang marks from a Western Green Mamba tend to be small. The snake in nature is almost exclusively arboreal, occasionally leaving the trees to descend to the ground to enter rodent burrows. Although generally shy and retreating with a tendency to avoid contact with man, the snake when alarmed may become agitated and aggressive, striking rapidly and accurately. People climbing in trees (in the native area) are most likely to be bitten. Multiple bites inflicted by a single snake or by more than one snake are 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. The probability of dry bites (no venom injected) in agitated Western Green Mamba strikes, however, is small.
- 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). Rapid heart rate to be expected.
- 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.
- OBSERVE PATIENT CLOSELY for signs and symptoms of envenomation which usually manifest between 15 minutes and two hours following the bite.
- 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 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 Pasteur Trivalent Mamba Antivenom is packaged as a pepsin-digested purified liquid form, and is ready for immediate use.
- Secure Four vials (40 mls) immediately, and withdraw the contents into a single syringe.
- Administer the undiluted Antivenom by direct intravenous at a rate of 1 vial (10 mls) per minute.
- 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 at a slower rate, 1 vial (10 mls) per 5 minutes.
- After the first four vials (40 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 four vials of antivenom immediately as directed above.
- Deliver this dose intravenously at a rate of 1 vial (10 mls) per 5 minutes.
- Release the bandage again slowly over 10 minutes.
- The patient should have received a total of 8 vials (80 mls) of antivenom at this point.
- Antivenom Therapy is the mainstay of treatment for Western Green Mamba envenomation. Many of the symptoms are ameliorated or entirely eliminated by the antivenom alone. Other symptoms will require additional therapeutic modalities. 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) tend to predominate the clinical picture in cases of mamba 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 or even intubation.
- Hematological symptoms may present as a Disseminated Intravascular Coagulopathy, and are treated as are other DICs. This, however, is rare with mamba envenomation.
- Renal symptoms are uncommon in mamba 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 always be given by intravenous infusion at a rate of ONE vial per 5 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.
8-12 vials total may be necessary for moderate or severe bites.
- It is advisable to perform periodic serum and urine analyses during therapy (as outlined above).
I. 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 concern. 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.
- Antibiotics are NOT recommended prophylactically.
- Multiple Bites:
- It is possible for a Western Green Mamba 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 (60mls) given: by direct intravenous infusion. Give the antivenom at a rate of 1 vial (10 mls) per 2 minutes. WATCH CLOSELY for signs of allergic response; correct reaction (as described below). Give all subsequent antivenom doses in ONE vial increments at a rate of 1 (10 mls) vial per 5 minutes as necessitated by the presence of continued signs and symptoms of envenomation.
- Severe Envenomation:
- If the patient shows severe signs of envenomation, particularly if early after the bite, up to 10 vials (100 mls) can be given as an INITIAL dose. Give the antivenom by direct intravenous infusion at a rate of 1 vial (10 mls) per 2 minutes. 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 Western Green Mamba envenomation are present.
- 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 Dendroaspis viridis:
- Clinical recordings of Western Green Mamba envenomations in which the snake was positively identified have been very few in number as compared with the significant number of annual envenomations and deaths due to the common Black Mamba (Dendroaspis polylepis polylepis). Recorded cases have demonstrated signs and symptoms similar to those seen with the Black Mamba, and have been characterized with systemic neurotoxicity.
- Prompt administration of S.A.I.M.R. Polyvalent Antivenom (or an equivalent Western Green Mamba-specific antivenom) has resulted in rapid recovery in many cases. Delay in administration or insufficient dosages of antivenom may allow serious neurological symptoms and respiratory paralysis to manifest which may be very difficult to reverse once established. Serious envenomations will require full intensive care with supportive treatment as indicated. 4 to 8 vials total of antivenom appears to be the average used in most cases; up to 12 or more vials have been used in serious cases.
- In Africa, the Black Mambas are considered to be the most dangerous of snakes, and are highly feared. The Green Mambas are thought to be significantly less aggressive and less toxic, with specific differences found in the venom components as compared with the Black Mambas. Black Mambas are also larger and produce larger quantities of venom. Mortalities have been recorded from Western Green Mamba bites, most of these cases involved bites which occurred in the field, and in which administration of antivenom was unavailable,neglected or delayed. There have been cases of spontaneous recovery from envenomations without the use of specific antivenom. However, untreated Western Green Mamba bites are at a substantially higher risk for major morbidity and fatality.
- The Eastern Green Mamba (Dendroaspis angusticeps) which is restricted to the forests of eastern Africa, although superficially similar in appearance and possibly in clinical presentation has been shown to possess differences in venom components and antigenic makeup, and requires a different specific antivenom. The Eastern and Western Green Mambas are not subspecies or races.
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.
- INSTITUTE PASTEUR PRODUCTION: Pasteur Antidendroaspis (Mamba) Venom Serum. (Package Insert with Antivenom), June 1981.
- GRAY, H.H: Green Mamba Envenomation: Case Report, Trans. R. Soc. Trop. Med. Hyg., 56(5):390, 1962. (Included for description of envenomation; therapy is out-moded and incorrect)
- Recommended reading although not specifically Western Green Mamba-
- SAUNDERS, C.R.: Report on Black Mamba Bite of a Medical Colleague. Cent. Afr. J. Med., 26:121, 1980.
- BLAYLOCK, R.S.: (to the editor) Black Mamba Envenomation. S. Afr. Med. J., 68:293, 1985.
- CRISP, N.G.: (to the editor) Black Mamba Envenomation. S. Afr. Med. J., 68:293, 1985.