First aid for snake bite
\nThe fi rst aid currently recommended is based around the mnemonic \u2018R.I.G.H.T\u2019.
\nThe details are provided in Table no.6 .
\nTable No. 6: Currently recommended First aid
\n\u2022 R. = Reassure the patient.
\n(70% of all snakebites are from non-venomous species. Only 50% of bites by
\nvenomous species actually envenomate the patient)
\n\u2022 I = Immobilise in the same way as a fractured limb.
\n(Use bandages or cloth to hold the splints, not to block the blood supply or
\napply pressure. Do not apply any compression in the form of tight ligatures,
\nthey don\u2019t work and can be dangerous!)
\n\u2022 G. H. = Get to Hospital Immediately.
\n(Traditional remedies have NO PROVEN benefi t in treating snakebite).
\n\u2022 T= Tell the doctor of any systemic symptoms such as ptosis that manifest on
\nthe way to hospital.
\nThis method will get the victim to the hospital quickly, without recourse to
\ntraditional medical approaches which can delay effective treatment.
\nTraditional fi rst aid methods followed for snakebite:
\nThe traditional methods such as application of tourniquet, cutting (incision) and
\nsuction, washing the wound, snake stone or other methods have adverse effects and
\nhence, they have to be discarded. The mneumonic used to recall some of the traditional
\nmethods followed is \u201cWHISTTLE\u201d and these are described below.
\nWashing the Wound:
\nVictims and bystanders have a tendency to wash the wound to remove any venom
\non the surface. This should not be done as the action of washing increases the fl ow of
\nvenom into system by stimulating the lymphatic system.
\nHousehold remedies:
\nVarious forms of household remedies are applied to the site of bite which may
\nenhance absorption of venom<\/p>\n
(Incision) Cutting and Suction:
\nCutting the site of bite and suctioning incoagulable blood increases the risk of
\nbleeding to death as well as increases the risk of infection. Venom is not cleared or
\nremoved from the snakebite site by this method.
\nSnake stone:
\nSnake stone is applied to the site of bite saying that it will absorb the venom and
\nfalls once the venom is absorbed. This contributes to delay in seeking appropriate
\nhealth care.
\nTourniquets:
\nTight tourniquets made of rope, string and cloth, have been followed traditionally
\nto stop venom fl ow into the body following snakebite. The problems noticed with
\ntourniquets are :-
\n\u2022 Risk of ischemia and loss of the limb
\n\u2022 Risk of necrosis
\n\u2022 Risk of massive neurotoxic blockade
\n\u2022 Risk of embolism if used in viper bites.
\n\u2022 Release of tourniquet may lead to hypotension.
\n\u2022 Gives patient a sense of false security, which encourages them to delay their
\njourney to hospital
\nThermal methods:
\n\u2022 Cautery treatment is followed in some areas. It is injurious and not
\nbenefi cial
\n\u2022 Cryotherapy involving the application of ice to the bite was proposed in the
\n1950\u2019s. It was subsequently shown that this method had no benefi t and merely
\nincreased the necrotic effect of the venom.
\nLocal application of anti snake venom:
\nLocal application of anti snake venom has not shown any benefi cial effects
\nElectrical Therapy:
\nElectric shock therapy for snakebite received a signifi cant amount of press
\ncoverage in the 1980\u2019s. The theory behind it stated that applying an electric current tothe wound denatures the venom. Much of the support for this method came from letters
\nto journals and not scientifi c papers. It has been demonstrated that the electric shock
\nhas no benefi cial effect and hence, it has been abandoned as a method of fi rst aid.
\nPressure Immobilisation Method (PIM)
\nPIM was developed in Australia in 1974 by Sutherland and gained some supporters
\non television and in the herpetology literature. Some medical textbooks have referred
\nto it. Further work done by Howarth demonstrated that the pressure, to be effective,
\nwas different in the lower and upper limbs. The upper limb pressure was 40-70mm
\nof Mercury; the lower limb was 55-70mm of mercury. Work carried out by Norris
\nshowed that only 5% of lay people and 13% of doctors were able to correctly apply
\nthe technique. In addition, pressure bandages should not be used where there is a risk
\nof local necrosis, that is in 4\/5 of the medically signifi cant snakes of India. In view of
\nthe diffi culties encountered at every level, Pressure Immobilisation Method cannot be
\nrecommended for use at present.
\nNewer Methods
\n\u2018Pressure Pad or Monash Technique\u2019
\nInitial research has suggested that a \u2018Pressure Pad or Monash Technique\u2019 may have
\nsome benefi t in the fi rst aid treatment of snakebite. This method should be subjected
\nto further research in India to assess its effi cacy. It may have particular relevance to
\nthe Indian Armed Forces who carry Shell Dressings as part of their normal equipment,
\nand would thus be ideally equipped to apply effective fi rst aid in diffi cult geographic
\nsettings where the need is great.
\nTreatment:
\nWhile dealing with a case of snake bite consider the mnemonic \u2018RASI\u2019.
\n\u2022 Remember principles ( \u201c12 As\u201d )
\n\u2022 Address the problems \u2013 clinical and social
\n\u2022 Seek help from others when required and
\n\u2022 Inform the patient and \/ or care givers on the status of illness, clinical course,
\nmanagement, outcome, welfare measures and follow up clearly with empathy.
\nPrinciples involved in the management of snake bite
\nThe principles while managing cases of snake bite at any Health Centre are clubbed
\nunder \u201c12 As\u201d<\/p>\n
Table No. 7: Principles involved in the management
\n1. Admit the victim immediately.
\n2. Ask effectively.
\n3. Assess quickly.
\n4. Act swiftly.
\n5. Administer medication meticulously.
\n6. Address to the wound properly.
\n7. Anticipate complications keenly.
\n8. Avoid errors carefully.
\n9. Ascertain the status repeatedly.
\n10. Amicable with patients and care givers and show empathy.
\n11. Advise on follow up accordingly.
\n12. Arrange for referral early.
\n1] Admit all victims of snake bite & Keep the victims under observation for 24 to 48
\nhours
\n2] Ask effectively to get the following \u2013
\na] Ask for the description of the snake, which has bitten the patient. If snake is
\nbrought try to identify the snake with the help of snake picture chart.
\nb] Ask for the site of bite and check the site. Never be carried away, by bite marks
\neither for diagnosis or for assessment of severity.
\nc] Ask for the time of the bite and correlate with the progression of symptoms and
\nsigns due to snakebite provided in page vide supra.
\nd] Ask for the details of traditional medicines or household remedies used, as it
\nmay sometimes cause confusing symptoms or interfere with other drugs to be
\nadministered.
\n3] Assess the following quickly.
\na] Airway, Breathing and Circulation
\nb] Vitals HR, RR, BP and oxygen saturation by Pulse oximetry (if required)
\nc] Chest expansion, and the ability to put out the tongue beyond incisors and
\ncounting the numbers at the bed side.
\nd] Site of snake bite along with regional lymphadenitis clinically from head to
\nfoot as well as back
\ne] For associated co-morbid illness[es]
\nf] For consuming any medication[s]
\ng] The status of envenomation – local systemic (neurotoxic, hemotoxic, myotoxic)
\nor a combination of them
\n4] Act swiftly
\na] Support Airway, Breathing and Circulation
\nb] Start IV line [fl uid for children refer to Annexure II \u2013Table No.29]<\/p>\n
c] Provide supportive measures depending upon the requirements including blood
\ntransfusion \/ components if required.
\nd] Connect to ventilator if there is a need
\n5] Administer medications meticulously
\na] Tetanus Toxoid injection intramuscularly
\nb] Anti snake venum as IV drip if needed \u2013 described vide infra
\n(ASV is composed of large molecules (IgG or fragments) and are absorbed
\nslowly via lymphatics, making the bioavailability by this route poor as
\ncompared to intravenous administration. Also, intramuscular injections
\nare not preferred as it could cause pain on injection and risk of hematoma
\nformation and sciatic nerve damage in patients with hemostatic abnormalities.
\nIntramuscular injections should only be given in settings where intravenous
\naccess cannot be obtained and \/ or the victim cannot be transported to a hospital
\nimmediately).
\nc] Ionotropics as IV drip if required
\nd] Antimicrobials if necessary
\ne] IV fl uids as per need [fl uid for children refer to Annexure II \u2013 Table No.29]
\nf] Other supportive medications including medicines to relieve pain (avoid
\naspirin) as per need.
\n6] Address to the wound properly
\nRemember the surigcal issues described vide infra and Table 11 in addition to the
\nfollowing.
\na] Wound following snake bite may show bite marks with or without laceration.
\nb] Sometimes venom may penetrate deep and hence deeper tissues may be
\ndamaged which may not be visible during initial examination.
\nc] At the site of bite, bleb or vesicle may develop and end in the form of an ulcer
\nwhich is a non specifi c one. (Non-specifi c ulcers are defi ned as ulcers due to
\ninfection of wounds, physical or chemical agents or due to local irritation).
\nd] Consider the following while managing the wound \/ ulcer.
\n\u2022 Minimize unnecessary blood loss
\n\u2022 Avoid the formation of a hematoma
\n\u2022 Initiate adequate cleaning with normal saline or tap water, debridement,
\nand edema control
\n\u2022 Remove debris and necrotic tissue, irrigate gently with water \/ normal
\nsaline
\n\u2022 Expose viable tissues, excise eschar after controlling hemotoxic
\ncomplications
\n\u2022 Use topical antibacterial agents
\n\u2022 Apply dressings after complete debridement.<\/p>\n
Maintain proper wound environment and prevent ischemia.
\n\u2022 Keep the bacterial count as low as possible.
\n\u2022 Facilitate healing of acute wound by applying non adherent dressing to
\nensure adequate epithelialisation and to prevent contamination of the
\nwound.
\n\u2022 Keep wounds clean and dry.
\n\u2022 Avoid soaking or scrubbing the wound.
\n\u2022 Teach & explain the care of wound to the patients.
\n\u2022 Educate on good personal hygiene and nutrition.
\n\u2022 Control diabetes if identifi ed.
\n7] Anticipate complications keenly.
\na] Examine the victims at regular intervals for alterations in symptoms and signs
\nb] Observe for anti snake venom related systemic changes and drug toxicity and
\nmanage them as described vide infra under treatment for ASV reactions.
\n8] Avoid errors carefully while assessing the case, investigating the victims,
\nadministering medications, following the case at hospital, undertaking any procedures,
\nreferring to other specialists or hospital, communicating with patient \/ and care
\ngivers, and planning for discharge as well as preparing reports, fi lling up the forms,
\nreviewing the data and conducting the audit.
\n9] Ascertain the status repeatedly and provide supportive measures as these cases
\nof snake bite victims may develop covert signs during hospital stay while on
\ntreatment.
\n10] Amicable interaction with patient and care givers with empathy is essential in
\nview of the socio clinical aspects of snake bite.
\n11] Advise on follow up accordingly in view of the systemic toxicity and the nature of
\nwound following snake bite. Patients may be also motivated to attend the nearest
\nHealth centre \/ Hospital for follow up care. Follow-up checks are required for
\nassessment of long term effects on different organs \/ systems and for appropriate
\nmanagement wherever required \/ needed.
\n12. Arrange for referral early – One should also remember the criteria for referral and
\nprovide clear instructions while referring the case. The details on referral aspects
\nof snake bite is provided vide infra in Table 15.
\nPharmacological aspects of Anti snake venom
\nThe goals of pharmacotherapy with injection Anti snake venom (ASV) are to
\nneutralise the venom, reduce morbidity and mortality, and prevent complications.<\/p>\n
Currently available Anti Snake Venom (ASV) in India is polyvalent i.e., it is effective
\nagainst all the four common species; Russells Viper (Daboia russelii), Common
\nCobra (Naja naja), Common Krait (Bungarus caeruleus) and Saw Scaled Viper (Echis
\ncarinatus). Indian ASV is a F(ab)2 product derived from horse serum and has a halflife
\nof over 90 hours. Though it is purifi ed, it still can be immunogenic.
\nAt present, no monovalent ASV is available primarily because there are no objective
\nmeans of identifying the snake species, in the absence of the dead snake. Moreover it
\nis diffi cult for the physician to determine which type of Monovalent ASV to employ
\nin treating the patient. In addition there are diffi culties to prepare, supply and maintain
\nadequate stock of species specifi c monovalent ASV.
\nThere are other known species such as the Hump-nosed pitviper (Hypnale hypnale)
\nwhere polyvalent ASV is known to be ineffective. In addition, there are regionally
\nspecifi c species such as Sochurek\u2019s Saw Scaled Viper (Echis sochureki) in Rajasthan,
\nwhere the effectiveness of polyvalent ASV may be questionable. Further work has
\nto be carried out with ASV producers to address this issue of preparing ASV useful
\nagainst other poisonous snakes observed in India.
\nIn India ASV is manufactured by Bengal Chemicals & Pharmaceuticals, Kolkata;
\nBharat Serums, Mumbai; Biological Evans, Hyderabad; Central Research Institute,
\nKausali; Haffkins Pharmaceuticals, Mumbai; King Institute of preventive medicine,
\nChennai; Serum Institute, Pune and Vins bio-products, Hyderabad.
\nASV is produced in both liquid and lyophilised forms. There is no evidence to
\nsuggest which form is more effective and many doctors prefer one or the other based
\npurely on personal choice. Liquid ASV requires a reliable cold chain and refrigeration
\nand has a 2 years shelf life. Lyophilised ASV, in powder form, requires only to be kept
\ncool and hence, is useful in remote areas where power supply is inconsistent. The
\ndetails of pre hospital treatment and issues related to ASV may be recorded in the form
\nprovided in Annexure IV.
\nASV Administration
\nCriteria
\nASV is prepared from animal and hence, it should only be administered when there
\nare defi nite signs of envenomation. Anti-Snake Venom carries risks of anaphylactic
\nreactions and should not therefore be used unnecessarily. Unbound, free fl owing
\nvenom, can only be neutralised when it is in the bloodstream or tissue fl uid. Also it
\nis a scarce and costly commodity. Hence, ASV may be administered only if a patient
\ndevelops one or more of the following signs \/ symptoms.<\/p>\n
Systemic envenoming
\n\u2022 Evidence of coagulopathy primarily detected by 20 WBCT or visible
\nspontaneous systemic bleeding, bleeding gums, etc., Further laboratory tests for
\nthrombocytopenia, Hb abnormalities, PCV, peripheral smear etc may provide
\nconfi rmation, but 20 WBCT is paramount.
\n\u2022 Evidence of neurotoxicity: ptosis, external ophthalmoplegia, muscle paralysis,
\ninability to lift the head etc.,
\n\u2022 Cardiovascular abnormalities: hypotension, shock, cardiac arrhythmia,
\nabnormal ECG.
\n\u2022 Persistent and severe vomiting or abdominal pain.
\nLocal envenomation (Refer Table No: 4)
\nPurely local swelling, even if accompanied by a bite mark from an apparently
\nvenomous snake, is not grounds for administering ASV if a tourniquet or tourniquets
\nhave been applied. These themselves can cause swelling. Once they have been removed
\nfor 1 hour and the swelling continues, then it is unlikely to be as a result of the tourniquet
\nand administration of ASV may be justifi ed.
\nDosage
\nIn the absence of defi nitive data on the level of envenomation, symptomatology is
\nnot a useful guide to the level of envenomation. Any ASV regimen adopted is at best
\nonly an estimate. What is important is to establish a single guideline which could be
\nadhered to, in order to enable sensitization results to be reliably reviewed.
\nThe recommended dosage level has been based on published research that Russells
\nViper injects on average 63mg (SD 7) of venom. Logic suggests that our initial
\ndose should be calculated to neutralise the average dose of venom injected. This ensures
\nthat the majority of victims should be covered by the initial dose and keeps the cost of
\nASV to acceptable levels. The range of venom injected is 5mg to 147mg.
\nOne vial of ASV neutralises 6mg of Russells Viper venom. So, to neutralize
\n63mg of venom, 10 vials are needed. Not all victims will require 10 vials as some may
\nbe injected with less than 63mg. However, starting with 10 vials ensures that there is
\nsuffi cient neutralising power to neutralise the average amount of venom injected and
\nduring the next 12 hours to neutralise any remaining free fl owing venom.
\nWarrell et al based on their study have shown that test doses for ASV have no
\npredictive value in detecting anaphylactoid or late serum reactions and should not
\nbe used. These reactions are not IgE mediated but Complement activated. They may
\nalso pre-sensitise the patient and thereby create greater risk. For Neurotoxic \/ Anti
\nHaemostatic envenomation, 8 to 10 vials of ASV is recommended to be administered<\/p>\n
as initial dose. Children receive the same ASV dosage as adults, as snakes inject the
\nsame amount of venom into adults and children. The ASV is targeted at neutralising
\nthe venom.
\nAdministration
\nASV may be administered in two ways over a period of one hour at a constant speed
\nand the patient should be closely monitored for 2 hours:
\n\u2022 Infusion: liquid or reconstituted ASV is diluted in 5-10ml\/kg body weight
\nof isotonic saline or glucose and administered as infusion usually. (Fluid
\nrequirement for children refer to Annexure II)
\n\u2022 Intravenous Injection: Rarely reconstituted or liquid ASV is administered by
\nslow intravenous injection. (2ml \/ minute). Each vial is 10ml of reconstituted
\nASV.
\nFacts to be remembered before \/ while using of Anti Snake Venom (ASV)
\n1. ASV is available in a polyvalent form and marketed in liquid or lyophilised
\npreparations in 10ml vial \/ ampoule.
\n2. Remember to use and maintain cold chain syst\u00e9m for liquid form. Users are
\ninformed to ascertain whether the cold chain is maintained.
\n3. There is no dose adjustment for ASV administration for children.
\n4. Before administering ASV, health staff should read and check the status of vial or
\nampoule containing ASV.
\n5. Elicit history of prior exposure to ASV. If a patient had received ASV earlier
\nand comes back with features of snake envonemation again, he \/ she has to be
\nconsidered as a fresh case and treated accordingly. However, care should be taken
\nwhile administering ASV, since he \/ she has been sensitised.
\n6. ASV treatment should not be initiated without adequate agents for managing
\nanaphylaxis or anaphylactoid reaction.
\n7. Anaphylactic or late serum sickness cannot be determined or prevented by test
\ndose.
\n8. ASV neutralises the unbound venom, hence give it early.
\n9. ASV administration should not be delayed or denied on the grounds of anaphylactic
\nreactions to a deserving case.
\n10. ASV is required only to those who show defi nite signs and symptoms of
\nenvenomation.
\n11. ASV should not be pushed as IV bolus or IM directly. ASV has to be administered
\nslowly as IV infusion in normal saline or glucose water over a period of one hour.
\n12. Local administration of ASV near the site of bite has been proven to be ineffective
\nand painful, and raises the intra-compartmental pressure, particularly in the digits.
\nHence, it should not be adopted.<\/p>\n
13. There is no prophylactic dose of ASV.
\n14. Total dose requirement cannot be decided on the basis of (WBCT) Whole blood
\nclotting test (or) clinical signs and symptoms.
\n15. Even if the patient develops reaction(s), the total dose required should be
\nadministered slowly after the patient recovers from the reaction(s).
\n16. There is no other drug of choice other than ASV for the treatment of poisonous
\nsnakebite.
\n17. The patient has to be closely monitored for manifestations of reactions to ASV for
\natleast 2 hours continuously.
\n18. No interaction with ASV has been reported.
\n19. Fetal risk due to ASV has not been established or studied in humans.
\n20. Safety status for use of ASV during pregnancy has not been established.
\n21. Timely administration of ASV will not guarantee the recovery or protect the
\nindividual from the venom induced toxicity or complications defi nitely.
\nASV Reactions
\n* Reaction to ASV develop usually within 15 to 30 minutes or within 2 hours. So
\nmonitor the case on ASV at 5min. interval for fi rst 30min. and then at 15min.
\ninterval for two hours. The details of pre hospital treatment and issues related
\nto ASV may be recorded in the form provided in Annexure IV.
\n* Some times, anaphylaxis (Type I) following ASV may develop rapidly and
\ndeteriorate into a life-threatening emergency, and hence anticipate and observe
\nfor it in every case. If the correct guidelines are followed, anaphylaxis can be
\neffectively treated.
\n* Therefore get alert if the patient develops of any reactions to ASV as shown in
\nTable no: 8.
\nTable No. 8: Manifestations of immediate reactions to ASV<\/p>\n
Itching (often over the scalp)
\n\u2022 Urticaria, even a single spot
\n\u2022 Nausea
\n\u2022 Vomiting
\n\u2022 Abdominal colic \/ pain
\n\u2022 Diarrhoea
\n\u2022 Tachycardia (PR >120\/min) (for
\nchildren refer age specifi c chart)
\n\u2022 Fall in blood pressure
\n\u2022 Low volume pulse<\/p>\n
Dry cough
\n\u2022 Bronchospasm \/ rhonchi
\n\u2022 Stridor (rarely)
\n\u2022 Angio-oedema of lips and mucous
\nmembrane
\n\u2022 Fever
\n\u2022 Shaking chills (rigors)
\n\u2022 Sweating
\n\u2022 Cold and clammy skin
\n\u2022 Central cyanosis
\n\u2022 Febrile convulsions (in children)
\n\u2022 Anaphylaxis (Type I )<\/p>\n
Treatment for ASV reactions
\n\u2022 Discontinue ASV
\n\u2022 Maintain IV line
\n\u2022 Administer Inj. Adrenaline 0.5ml of 1:1000 IM, (Adults) \/ Inj. Adrenaline
\n0.1ml\/Kg body weight of 1:10,000 IM (paediatric dose). Details are provided
\nin Table no.9.
\n(If after 10 to 15 minutes the patient\u2019s condition has not improved or is worsening,
\na second dose of 0.5 ml of Adrenaline IM is given. This can be repeated for a third
\nand fi nal occasion but in the vast majority of reactions 2 doses of Adrenaline will
\nbe suffi cient).
\nStudies have shown that adrenaline reaches necessary blood plasma levels in
\n8 minutes in the IM route, and in 34 minutes in the subcutaneous route . The early use
\nof adrenaline has been selected as a result of study evidence suggesting better patient
\noutcome if adrenaline is used early.
\nIn extremely rare, severe life threatening situations, 0.5mg of 1:10,000 adrenaline
\ncan be given IV slowly. This carries a risk of cardiac arrhythmias however, and
\nshould only be used if IM adrenaline has been tried and the administration of IV
\nadrenaline is in the presence of ventilatory equipment and ICU trained staff.<\/p>\n
Table No. 9: Dosage of adrenaline for adults and children<\/p>\n
Adults
\nInject adrenaline 1:1000 intramuscularly:
\n\u2022 Weighing < 50 kg give 0.25 ml
\n\u2022 Weighing 50 -100 kg give 0.50 ml
\n\u2022 Weighing >100 kg give 0.75 ml<\/p>\n
*Children (upto 25 kg)<\/p>\n
Inject adrenaline 1:10,000 dilute
\n1ampoule (1 ml) of adrenaline 1:1000
\nwith 9ml water for injection or normal
\nsaline.
\nInject intramuscularly 1:10,000
\nadrenaline according to the guide
\n(approximates to 0.1ml\/kg).
\n\u2022 1 year (10 kg) give 1 ml
\n\u2022 3 years (15 kg) give 1.5ml
\n\u2022 5 years (20 kg) give 2ml
\n\u2022 8 years (25 kg) give 2.5ml
\n\u2022 Children > 25 kg as for small
\nadults<\/p>\n
Approximate body weight for children may be calculated by the formula;
\n\u2022 2 x Age + 9 = weight in kg.<\/p>\n
Start an adrenaline infusion if the patient remains shocked, (preferably via a
\ncentral venous line), commencing at 0.25 microgram\/kg\/minute, and titrating as
\nrequired to restore blood pressure. Large doses of adrenaline may be needed.
\nConsider additional measures:
\n\u2022 Administer Salbutamol or Terbutaline by aerosol or nebuliser (Beta2 agonists)
\nfor bronchospasm.
\n\u2022 Antihistamines: Administer both H1 receptor blockers Inj. Chlorpheniramine
\nmaleate 10 – 20mg as IV \/ intramuscularly or Promethazine 0.5 – 1mg\/kg
\nand H2 receptor blockers Inj.Ranitidine 1mg\/kg or Famotidine 0.4mg\/kg or
\nCimetidine 4mg\/kg slowly intravenously.
\n\u2022 The dose for children is of Pheniramine maleate at 0.5mg\/kg\/day IV
\nor Promethazine HCl can be used at 0.3 – 0.5mg\/kg IM or 0.2mg\/kg of
\nChlorpheniramine maleate IV, and 2mg\/kg of Hydrocortisone IV, antihistamine
\nuse in pediatric cases must be deployed with caution.
\n\u2022 Administer Corticosteroids intravenously: Hydrocortisone 2 – 6mg\/kg or
\nDexamethasone 0.1 – 0.4mg\/kg
\n\u2022 Try nebulised Adrenaline (5ml of 1:1000) in case of laryngeal oedema which
\noften will ease upper airways obstruction. However, do not delay intubation if
\nupper airways obstruction is progressive.
\n\u2022 IV fl uids should be given for haemodynamic instability.
\n\u2022 Once the patient has recovered, the ASV can be restarted slowly for
\n10 – 15minutes, keeping the patient under close observation. Then the normal
\ndrip rate should be resumed.
\n\u2022 Monitor vitals and provide supportive measures
\nLate Serum sickness reactions (delayed hypersensitivity) to ASV
\nSerum sickness may occur one to two weeks after administration of ASV. Late
\nSerum sickness reactions can be easily treated with an oral steroid such as prednisolone,
\nadults 5mg 6 hourly, paediatric dose 0.7mg\/kg\/day. (Duration of treatment has to be
\nadjusted with case). Oral H1 Antihistamines provide additional symptomatic relief.
\nPrevention of ASV Reactions \u2013 Prophylactic Regimens
\nThe conclusion in respect of prophylactic regimens to prevent anaphylactic
\nreactions, is that there is no evidence from good quality randomized clinical trials to
\nsupport their routine use. If they are used then the decision must rest on other grounds,
\nsuch as policy in the case of hospitals, which may opt for a maximum safety policy,
\nirrespective of the lack of defi nitive trial evidence.<\/p>\n
Two prophylactic regimens normally recommended are given below:
\n\u2022 100mg of Hydrocortisone and H1 antihistamine (10mg Chlorphenimarine
\nmaleate; or 22.5mg IV Phenimarine maleate IV or 25mg Promethazine
\nhydrochloride IM) 5minutes before ASV administration. The dose for children
\nis 0.1-0.3mg\/kg of antihistamine IV and 2mg\/kg of Hydrocortisone IV.
\nAntihistamine should be used with caution in pediatric patients.
\n\u2022 0.25-0.3mg Adrenaline 1:1000 given subcutaneously.
\nIf the victim has a known sensitivity to ASV, pre-medication with adrenaline,
\nhydrocortisone and anti-histamine may be advisable, in order to prevent severe
\nreactions.
\nRepeat Doses of ASV in Neurotoxic Envenomation
\nThe ASV regime relating to neurotoxic envenomation has caused considerable
\nconfusion. If on reassessment after 1 – 2hrs the initial dose has been unsuccessful in
\nreducing the symptoms \/ if the symptoms have worsened \/ if the patient has gone into
\nrespiratory failure then a further dose should be administered. This dose should be
\nthe same as the initial dose, i.e., if 10 vials were given initially then 10 vials should
\nbe repeated for a second dose and then ASV is discontinued. 20 vials is the maximum
\ndose of ASV that should be given to a neurotoxically envenomed patient.
\nOnce a patient in respiratory failure, has received 20 vials of ASV and is supported
\non a ventilator, ASV therapy should be stopped. This recommendation is due to the
\nassumption that all circulating venom would have been neutralised by this point.
\nTherefore further ASV serves no useful purpose.
\nEvidence suggests that \u2018reversibility\u2019 of post synaptic neurotoxic envenoming is
\nonly possible in the fi rst few hours. After that the body recovers by using its own
\nmechanisms. Large doses of ASV, over long periods, have no benefi t in reversing
\nenvenomation.
\nConfusion has arisen due to some medical text books and journal articles
\nsuggesting that \u2018massive doses\u2019 of ASV can be administered, and that there need
\nnot necessarily be a clear-cut upper limit to ASV. These texts are talking about snakes
\nwhich inject massive amounts of venom, such as the King Cobra or Australian Elapids.
\nThere is no justifi cation for massive doses of 50+ vials in India, which usually results
\nin the continued use of ASV whilst the victim is on a ventilator. No further doses of
\nASV are required; unless a proven recurrence of envenomation is established.
\nAdditional vials to prevent recurrence are not necessary.<\/p>\n
Repeat Doses of ASV in Anti Haemostatic envenomation
\nIn the case of anti haemostatic envenomation, the ASV strategy will be based around
\na six hour time period. When the initial blood test reveals a coagulation abnormality,
\nthe initial ASV amount will be given over one hour. No additional ASV will be given
\nuntil the next Clotting Test is carried out. This is due to the inability of the liver to
\nreplace clotting factors within 6 hours.
\nAfter 6 hours a further coagulation test should be performed and a further dose
\nshould be administered in the event of continued coagulation disturbance. This dose
\nshould also be given over one hour. Clotting tests and repeat doses of ASV should
\ncontinue on a 6 hourly pattern until coagulation is restored, unless a species is identifi ed
\nas one against which Polyvalent ASV is not effective.
\nThe repeat dose should be 5 -10 vials of ASV i.e., half to one full dose of the
\noriginal amount. The most logical approach is to administer the same dose again, as
\nwas administered initially. Some, argue that since the amount of unbound venom is
\ndeclining, due to its continued binding to tissue, and due to the wish to conserve scarce
\nsupplies of ASV, there may be a case for administering a smaller second dose. In the
\nabsence of good trial evidence to determine the objective position, a range of vials in
\nthe second dose has been adopted.
\nRecurrent Envenomation
\nWhen coagulation has been restored, no further ASV should be administered,
\nunless a proven recurrence of a coagulation abnormality is established. There is no
\nneed to give prophylactic ASV to prevent recurrence. Recurrence has been a mainly
\nU.S. phenomenon, due to the short half-life of Crofab ASV. Indian ASV is a F(ab)2
\nproduct and has a half-life of over 90 hours, and therefore is not required in a prophylactic
\ndose to prevent re-envenomation<\/p>\n
Anti Haemostatic Maximum ASV Dosage Guidance
\nThe normal guidelines are to administer ASV every 6 hours until coagulation has
\nbeen restored. However, what should the clinician do after say, 30 vials have been
\nadministered and the coagulation abnormality persists? There are a number of questions
\nthat should be considered.
\nFirstly, is the envenoming species one for which polyvalent ASV is effective?
\nFor example, it has been established that envenomation by the Hump-nosed pitviper
\n(Hypnale hypnale) does not respond to normal ASV. Coagulopathy can \/ may continue
\nfor up to 3 weeks as in the case of Hypnale.
\nThe next point to consider is whether the coagulopathy is resulting from the action
\nof the venom. Published evidence suggests that the maximum venom yield from say a
\nRussells Viper is 147mg, which will reduce the moment the venom enters the system
\nand starts binding to tissues. If 30 vials of ASV have been administered that represents
\n180mg of neutralising capacity, this should certainly be enough to neutralise free
\nfl owing venom. At this point the clinician should consider whether the continued
\nadministration of ASV is serving any purpose, particularly in the absence of proven
\nsystemic bleeding. At this stage the use of Fresh Frozen Plasma (FFP), cryoprecipitate
\n(fi brinogen, factor VIII) fresh whole blood, thrombocytes or coagulation factors can
\nbe considered, if available. Plasmapheresis has been used successfully under such
\ncircumstances amidst controversies. More clinical trails are warranted in these areas.
\nRecovery Phase
\nIf an adequate dose of antivenom has been administered, the following responses may
\nbe seen:
\na) Spontaneous systemic bleeding such as gum bleeding usually stops within
\n15 – 30 minutes.
\nb) Blood coagulability is usually restored in 6 hours. (Principal test is
\n20 WBCT).
\nc) Post synaptic neurotoxic envenoming such as the Cobra may begin to improve
\nas early as 30 minutes after antivenom, but can take several hours.
\nd) Presynaptic neurotoxic envenoming such as the Krait usually takes a
\nconsiderable time to improve refl ecting the need for the body to generate new
\nacetylcholine emitters.
\ne) Active haemolysis and rhabdomyolysis may cease within a few hours and the
\nurine returns to its normal colour during the course of treatment.
\nf) Patients in shock blood pressure may increase after 30 minutes while on
\ntreatment.<\/p>\n
ASV risk and wastage
\nDefi nitive diagnosis and proper utilisation of ASV helps the patient. Otherwise
\nthe patients are subjected to risk of receiving excessive \/ inadequate dosage of ASV.
\nMore over the availability of ASV and doctors views and experience may infl uence the
\nutilisation of ASV for a given patient. Thus there is a possibility of fi rst aid wastage of
\nASV. The details of provided in Table No.10.
\nTable No. 10: ASV \u2013 Risk and Wastage (Ian D.Simpson Model)<\/p>\n
| <\/td>\n | Low wastage<\/strong><\/td>\n| High wastage<\/strong><\/td>\n<\/tr>\n | High risk<\/td>\n | ASV – Not available<\/p>\n | – Insuffi cient<\/p>\n administration<\/td>\n ASV \u2013 Too little supply and species<\/p>\n | are different<\/td>\n<\/tr>\n Low risk<\/td>\n | Effective dose of ASV to<\/p>\n | envenomed patients<\/td>\n Receive ASV when not required<\/p>\n | Too much ASV when not required<\/p>\n Unnecessary ASV<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n","protected":false},"excerpt":{"rendered":" First aid for snake bite The fi rst aid currently recommended is based around the mnemonic \u2018R.I.G.H.T\u2019. The details are provided in Table no.6 . Table No. 6: Currently recommended First aid \u2022 R. = Reassure the patient. (70% of all snakebites are from non-venomous species. Only 50% of bites by venomous species actually envenomate […]<\/p>\n","protected":false},"author":3,"featured_media":0,"parent":21,"menu_order":3,"comment_status":"open","ping_status":"open","template":"","meta":{"footnotes":""},"class_list":["post-37","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/doctorbruno.info\/snake-bite-scorpion-sting-protocol\/wp-json\/wp\/v2\/pages\/37","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/doctorbruno.info\/snake-bite-scorpion-sting-protocol\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/doctorbruno.info\/snake-bite-scorpion-sting-protocol\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/doctorbruno.info\/snake-bite-scorpion-sting-protocol\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/doctorbruno.info\/snake-bite-scorpion-sting-protocol\/wp-json\/wp\/v2\/comments?post=37"}],"version-history":[{"count":0,"href":"https:\/\/doctorbruno.info\/snake-bite-scorpion-sting-protocol\/wp-json\/wp\/v2\/pages\/37\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/doctorbruno.info\/snake-bite-scorpion-sting-protocol\/wp-json\/wp\/v2\/pages\/21"}],"wp:attachment":[{"href":"https:\/\/doctorbruno.info\/snake-bite-scorpion-sting-protocol\/wp-json\/wp\/v2\/media?parent=37"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} |