scorpions bites by dr manoj chandrakar.. .

1. Scorpion sting Dr Manoj chandrakar MD and Ped . Intensivist Chandrakar children clinic (director) C onsultant ( shishu bhavan hospital )

2. Scorpion envenomation life threatening medical emergency. Tropical and subtropical region Summer / warm/ dry coastal / rural ( rich in red soil ) Night feeders ( max. sting at night ) Death due myocardial involvement , pulmonary edema , neurological complications.

3. In india , case fatality rate – 3% to 22%. Among 86 species , Poisnous scorpion – 1. H. tamulus ( mesobutubus tumulus ) , indian red scorpion and 2. P. swammerdami ( black scorpion ) India – cardiac main manifestation ( other countries – neurological (America/ Africa ) Common states – Maharashtra / Karnataka/ tamilnadu / pondichery /west Bengal

4. Indian Red Scorpion

5. Black scorpion

6. Pathopysiology Venom is mixtures of neurotoxic peptides , mucopolysachharides and other components Venom usually deposited deep into subcutaneous tissue Absorption completes within 7- 8 hours 70% reached into blood within 15minutes Venom acts as cardiotoxin , neurotoxin , nephrotoxin ,hemolytic toxin and enzymes Acts and alters voltage- dependent ion channel Alpha and beta toxins primarily affects sodium channels Toxin inhibits the inactivation of the ion channels , causing an autonomic storm and persistent neuronal excitation Myocardial dysfunction , pulmonary edema , hypertension , tachycardia and cool extremities due alpha toxin induced massive release of epinephrine, norepinnphrine and vasoactive peptides. Indian species mostly affects cardiovascular system.

7. Histamine and serotonin – local reaction Alpha / beta toxin and neurotoxin – CVS /CNS Hyaluronidase / peptides/ nucleotides/ aminoacids etc.- alter voltage dependent ion channels , ANS, CVS, CNS

8. Substance p / serotonin – local pain etc . Alpha, beta toxin – stimulate Na channel Autonomic storm Ibaritoxin – inhibits Ca and Na channel smooth muscle contraction Kallikrein / kinin – Bradykinin NCPE(acute)/ hypotension / shock/acute pancreatitis .

9. Envenomation grading Grade 1 – local manifestations : severe excruciating pain at sting site with radiating along corresponding dermatomes , mild edema , sweating at sting site without systemic involvement Grade 2 – Autonomic storm : acetylcholine excess or parasympathetic stimulation – vomiting , profuse sweating all over body , ropy (thick, sticky) salivation , bradycardia , premature ventricular contraction , hypotension , priapism in boys Sympathetic stimulation ( hypertension , tachycardia , cold extremities , systolic murmur Grade 3 – cold extremities , tachycardia , hypotension or hypertention with pulmonary edema ( tachypnea , basal crepts , or crackles ) Grade 4 – tachycardia , hypotension , with or without pulmonary edema with warm extremities ( warm shock )

10. Local manifestations Unbearable radiating pain at sting site usually toes and fingers Infants and young children – sudden onset of inconsolable cry , incessant crying Mild sweating , hypertension and bradycardia along with pain Mechanism – serotonin , bradykinin and substance –p for pain Tap sign – sudden tap at and arounds site of sting induces severe pain and withdrawal ( diagnostic sign ) Implication – severe pain at site without systemic involovemnt ( benign or dry s ting )

11. If local pain was severe , no further progression of symptoms Reapearance of severe pain with clinical improvement of peripheral circulation – indicative of recovery of envenomation

12. Systemic manifestations Usually due to autonomic storm ( massive release of catecholamins from adrenergic and cholinergic neurons and adrernal medulla ). Transient initial cholinergic phase that merge into more sustained adrenergic phase due to C holinergic stimulation – ( parasympathetic – early , short lived ) Vomiting ( serotonin in venom ) Cholinergic stimulation – sweating , salivation , bronchial secretion , priapism, bradycardia, VPCs , stimulate insulin Appear w ithin 1 to 2 hours lasts for 6 to 13 hours

13. Profuse sweating – sweat flow all over body ( skin diarrhea) . Persists for 3 to 17 hours Salivation – thick ropy salivation . Soon after sting and persists for 2 to 4hour hours . Excessive salivation and bronchial secretion can cause respiratory failure. Priapism – seen in almost all male children of all ages . Diagnostic of venomous scorpion sting persists for 5 to 16 hours.

14. Main complaints: Vomiting , P rofuse sweating , S alivation , P riapism are premonitory sign of cardiac signs of scorpion sting envenomation

15. Adrenergic stimulation ( late , prolonged) – Alpha – cold extremities , tachycardia , hypertension , and peripheral circulatory failure , myocardial injury and pulmonary edema Beta – tachycardia Cold extremities – severe vasoconstriction due catecholamines Persists for 12 to 26 hours Skin over palm , dorsum looks like washerman hand Associated with severe cvs manifaestations Recovery associated with improvement in skin temperature Mydriasis - dilated nonreacting or poorly reacting pupil in early phase of the a utonomic storm. Due to stimulation of alpha receptors , catecholamines induced

16. Tachycardia – within 4 hours of sting , persists for upto 24-72 hours Due to direct beta adrenergic stimulation of heart Impaired left ventricular filling , reduction in cardiac output due to marked tachycardia RESULTS in delirium and convulsion due to anoxia to brain Hypertension – alpha receptor stimulation induced vasoconstriction and beta receptor mediated increase in cardiac contractility Within 2 hours of sting lasts for 4-8 hours Hypertensive stress induced myocardial injury contribute to rhythm diturbances and ventricular failure

17. Hypotension – transient hypotensison ( vomiting, sweating , salivation , cardiac arrhythmia) Delayed hypotension – reduction in systemic vascular resistance , hypokinetic phase, decreased left ventricular contractility Appears 24 to 48 hours of admission Venom inhibits kinase 2 enzymes casing elevation of bradykinin (neuromuscular agent ) , involved in development of pulmonary edma and hypotension

18. Pulmonary edema – develops early as 30 minutes with hypertension and as late as 36 hours with hypotension and tachycardia Characterised by acute onset of cold extremities , sudden onset of cough , dyspnea tachycardia , systolic murmur , gallop, bilateral crepitation and fast thready and low volume pulse Inhbits insulin – hyperglycemia / increase pottasium . Other complications – neurological( direct toxicity – hemiparesis, stroke ( hemoorhagic /thrombosis) , acute pancreatitis, hematological , liver injury , bleeding and renal injury etc.

19. Investigations Cardiac markers – creatine kinase , cardiac troponin I and T , myoglobulin (early myocardial injury ) ECHO, ECG and chest x ray

20. Echo Abnormal echo within 12 hours to 15 hours of sting Global hypokinesia with reduced ejection fraction , decreased left ventricular performance , mitral regurgitation , abnormal diastolic filling pressure Serial echo Echo findings return to normal within 5 days to 4 weeks

21. ECG ST segment depression and peaked tall T waves or T wave inversion Arrowhead T wave looking like ashoka tree (early myocardial injury ) Tent shaped T wave look like Christmas tree (recovery of myocardial injury ) Early myocardial infarctions like paterrns , atrial arrhythmias , non sustained ventricular tachycardia , conduction defects PQRST or T wave alternanas Normalization may require 1 week to 4 week Poor prognostic – low voltage QRS complex ,wide QRS complex , tachycardia , hemiblock and marked ST segment depression

22. Chest x ray Cardiogenic pulmonary edema 1. unilateral distribution or bat wing appearance of lung edema due to left ventricular dysfunction and elevation of pulmonary vascular permeablility 2. patchy and peripheral distribution of lung edema with air bronchogram , due increased vascularity

23. T reatment

24. Treatment First – airway, breathing and circulation , then Pain relief and fluid management – Paracetamol (15mg/kg) every 4-6 hourly till resolution of pain Aspirin 10mg/kg orally every 4 hours for children Others – NSAIDS, Ice packs , xylocaine , midaz , or diazepam Maintainance fluids , if deficit then corrects Fluid – NS/RL/ DNS /0.45DNS

25. Vasodilators – 5 drugs ( prazosin , chlorpromazine , dobutamine , nitroglycerine, and sodium nitroprusside ) PRAZOSIN – competitive post synaptic alpha 1 receptor, adrenorecptor antagonist and first line treatment of scorpion venomation Subdues sympathetic effects and activates venom- inhibited potassium channels and decreases preload , afterload , blood pressure without increasing heart rate Vasodilatrion by cGMP pathway Both pharmacologic and celllular antidote Used in autonomic storm. Available as 1 mg tablet / 2.5 mg tablet ( minipress ) It is photosensitivity so stored in airtight container away from sunlight Dose – 30microgram /kg/dose( not sustained release )

26. Not be used when pain is only symptom Sudden drop BP after first dose of prazosin so don’t lift the child to prevent first dose phenomenon Close monitoring of vitals ( bp , pulse rate , respiration ) every 30 min for first 3 hours , every hour for next 6 hours , then every 4 hours till improvement Repeat dose after 3 hours of first dose (30 microgram /kg/dose) can be given. It should be given every 6 hourly for 48 hours or till extremities dry , warm , visible peripheral veins / clinical improvement In general – not more than 4 doses required in most patients Another durg – doxazosin

27. Before prazosin Era : lytic cocktail , propranolol, decongestive agents , insulin- glucose drip , steroid ( mortality – 20 to 29% ) Vasodilators / cardiac support era : 5 drugs , prazosin , chlorpromazine , dobutamine , nitroglycerine , sodium nitroprruside Prazosin Era : mortality ( < 1 %), morbidity (50%) Scorpion antivenom + Prazosin : morbidity ( 3.7%).

28. Clonidine : alpha 2 adrenergic receptor agonist , inhibits sympathetic activity Causes decrease heart rate and peripheral blood pressure But never evaluated in treatment of scorpion sting . Midazolam widely used in case of neurological symptoms That inhibits excitability of post synaptic neurons Advantage over other because of rapid distribution and short half life .

29. Management of pulmonary edema – Respiraotry support (noninvasive or invasive ) Fluid management Diuretics Improve cardiac output – dobutamine ( 5 – 15 microgram/kg/min ) , sodium nitroprruside (0.3-5 microgram /kg/min) or nitroglycerine (0.1-1 ug /kg/min) Dobutamine – increase contractility , increase cardiac index , and systolic blood pressure without increasing systemic vascular resistance and also reduces pulmonary artery occlusion pressure so reducing ventricular preload Nitroglycerin – reduce afterload and reduce pulmonary congestion (mainly acts on pulmonary vessels and vein ) Nitroprusside – predominant arteriolar dilator.

30. Impending CCF – dobutamine / milrinone /adrenaline/dopamine Shock/ hypotension – dopamine / dobutamine / adrenaline VPCs – self limiting , electrolyte correction , hydration , mexilitine VT- lidocaine / amiodarone / milrinone Ischemia – NTG / ? Glucose infusion

31. Scorpion antivenom Horse serum Poor availability Much faster response Dose - 3 vials(30ml) in 100ml NS over 30 min IV(irrespective of age and weight of patients ) , in case of grade 2 and above patients Prevent sympathetic overstimulation and decreases its complication 60ml of SAV at admission or repeat 30ml of SAV in children deteriorating / non resolving symptoms within or at end of 4-6 hours of admission 50 % children non resolving after 4 hours and 8 % patients deteriorated to higher grades.

32. Pain without systemic sign – DRY STING NO Pain 1. without systemic sign – observe 2. with systemic sign( sweating/cold extremities/HTN/priapism/ brady / tachy - poisonous sting

33. Unhelpful treatments Lytic cocktails ( pethidine + promethazine + chlopromazin ) Morphine Steroids Atropine Nifedipine ACE inhibitors

34. Key points Cardiac manifestsations are common in indian red scoprpin sting venomation alpha receptor stimulation role in myocardial dysfunction and acute pulmonary edema Prazosin is antidote and mortality reduces to less than 1 % Time interval between sting and adminstration of prazosin and or SAV for autonomic storm determines the outcome.

35. THANKS