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Environmental exposures

Environmental exposures. Nikki Waller, MD Medical Student Clerkship 2009-2010 Self-Directed Learning Assessments. Snakes. 8,000 venomous snake bites/yr in US ~10 deaths/yr 25% bites are dry bites Venomous: Imported snakes Coral Snakes Crotaline Snakes/Pit Vipers Rattlesnakes

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Environmental exposures

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  1. Environmental exposures Nikki Waller, MD Medical Student Clerkship 2009-2010 Self-Directed Learning Assessments

  2. Snakes • 8,000 venomous snake bites/yr in US • ~10 deaths/yr • 25% bites are dry bites • Venomous: • Imported snakes • Coral Snakes • Crotaline Snakes/Pit Vipers Rattlesnakes Copperhead Water Moccasin Massasauga www.zanesville.ohiou.edu

  3. Clinical Effects www.rk19-bielefeld-mitte.de

  4. Coral Snake • Brightly Colored • Black-Red-Yellow pattern • RED touches YELLOW = kill a fellow vs • Red on Black = venom lack • ONLY Eastern Coral Snake bite requires treatment www.zanesville.ohiou.edu

  5. Coral Snake • Eastern Coral Snake venom is potent neurotoxin • Symptoms: • Tremor • Salivation • Respiratory paralysis • Seizures • Bulbar palsies( dysarthria, diplopia, dysphsgia)

  6. Coral Snake • Admit for 24-48 hours observation • ALL patients with POTENTIAL envenomation – 3 vials of antivenim • Antivenim (M fulvius) • At least 3 vials • If sxs – additional doses • Symptomatic Pts are admitted to ICU

  7. Arizona Coral Snake • Sonoran(Arizona) Coral Snake bite does not require treatment • Few symptoms • Local wound care only www.pitt.edu

  8. Coral Snake Mimic • Red and yellow, kill a fellow; red and black, friend of Jack." www.stetson.edu jungledomain.org

  9. Coral Snakes in the US www.backyardnature.net/ snakvenm.htm

  10. Crotalinae (Pit Vipers) Bites • Identified by • 2 retractable fangs • Heat sensitive depressions (pits) located between each eye & nostril • Clinical Effects depend on: • Size & species of snake • Age & size of victim • Time since bite • Characteristics of bite

  11. Crotalinae (Pit Vipers) Bites • Hallmark of bite – fang marks with local pain & swelling • Severity classification: • Degree of local injury • Swelling, pain, ecchymosis • Degree of systemic toxicity • Hypotension, tacchycardia, paresthesias • Evolving coagulopathy • Thrombocytopenia, elevated PT, hypofibrinogenemia

  12. Crotalinae (Pit Vipers) Bites • Any 1 of the 3 classes = envenomation • No sxs at 8-12 hours = no bite or dry bite • All envenomations have swelling at 30 minutes • Rarely onset up to 12 hours • Degree of envenomation • Minimal: local sxs only • Moderate: systemic sxs and coagulation parameter abnormalities • Severe: extensive swelling, potentially life threatening systemic signs, markedly abnormal coagulation parameters that may result in bleeding

  13. Crotalinae (Pit Vipers) Bites • Diagnostic tests: CBC, Coags, Type & Screen • Treatment: • Resources: Arizona Poison Control 520-626-6016 • Prehospital: • Minimize physical activity & remain calm • Immobilize bite site & place in neutral position below heart

  14. Crotalinae (Pit Vipers) Bites • Treatment (continued): • Cardiac monitor, IV’s, resuscitate based on ACLS • Local wound care • Remove FB • Td Booster • Measure & Record limb circumference at several sites above and below site of bite, repeat q 30 minutes • Mark border of advancing edema q 30min

  15. CroFab • Polyvalent Crotalidae Immune Fab(CROFAB) • Any pt with progressive swelling, systemic sxs or coagulopathy • Sheep derived antivenim • Replaced Antivenin (Crotalidae) Polyvalent( equine derived) • Initial Dose: 4-6 vials IV • Diluted in 250ml H20 & infused over 60 mins • Dosing same for children, amount of diluent is adjusted • @1HR, if any of 3 parameters have not halted, repeat dose of 4-6 vials given • Labs checked q4 h or after each round of Crofab • End point is arrest of sxs and coagulopathy, IF NOT KEEP TREATING • After control of sxs, Protocol

  16. CroFab • @1HR, if any of 3 parameters have not halted, repeat dose of 4-6 vials given • Labs checked q4 h or after each round of Crofab • End point is arrest of sxs & coagulopathy, IF NOT KEEP TREATING • After control of sxs, Protocol as follows: • 2 vials q 6h for additional 18 hours ( 3 more doses)

  17. CroFab • The cost of CroFab is $ 750 per vial • Total cost of therapy for a snakebite ranges from $10500 (4-4-2-2-2 vials) to $13500 (6-6-2-2-2 vials) • Average treatment Cost: $10,000 per patient • Estimated 8,000 venomous snakebites in the US each year • Market potential of up to US$80 million/yr protherics.matinee.co.uk/ products/Critical_Care_Products.asp

  18. Compartment Syndrome • Pressure > 30 : limb elevation & repeat CroFab dosing • Persistently elevated Pressure • Mannitol 1-2 g/Kg IV over 30 minutes • Surgical Consult for Fasciotomy

  19. Crotalinae (Pit Vipers) Bites • DISPOSITION • Observe for at least 8 hours • Severe bites and anyone receiving continued antivenin -> ICU • Must warn patients about Serum Sickness with Crofab • 16% patients • 7-14 days after therapy • Tx with Prednisone 60mg/d PO tapered over 1-2 weeks

  20. Pit Vipers in the US Western Diamondback Rattlesnake Habitat Eastern Diamondback Rattlesnake Habitat

  21. Gila Monster Bite • Tenacious bite • Often lizard still attached • To remove: • Place lizard on solid surface • Submersion in water • Cast Spreader • Local irritating flame • Local wound care • Search for teeth • No further treatment required www.californiaherps.com www.mendosa.com

  22. Gila Monster Bite • Symptoms: Pain & swelling • Rare systemic toxicity • Systemic SXS: • Diaphoresis • Paresthesia • Weakness • HTN www.aintitcool.com

  23. Gila Monster Habitat www.pueblozoo.org

  24. Hypothermia: Epidemiology • Defined as a core temperature < 35°C (95°F) • US Deaths:700 per yr • Half > 65 yo • At Risk: Age Extremes & Altered sensorium • “Causes of Hypothermia: Clinical Settings • “Accidental” (environmental) • Metabolic • Hypothalamic and CNS dysfunction • Drug-induced • Sepsis • Dermal disease • Acute incapacitating illness • Iatrogenic (fluid resuscitation)

  25. Hypothermia • ETIOLOGIES: • Metabolic causes • Hypothyroidism, hypoadrenalism, hypopituitarism • Each lead to a decrease in metabolic rate • Hypoglycemia also may lead to hypothermia • CNS dysfunction • Head trauma, tumor, stroke • Wernicke disease • Potentially reversible with thiamine • Alcohol & Drugs • In the US, most hypothermic patients are intoxicated • Ethanol • Vasodilator & anesthetic and CNS depressant effects • Don’t Feel the Cold and Don’t respond to it

  26. Hypothermia • ETIOLOGIES: • Sepsis • Poor prognostic factor in patients with bacteremia • Severe infections, DKA, immobilizing injuries, and various other conditions impair thermoregulatory function • Trauma patients • Resuscitation with room-temperature fluid & cold blood • At risk: Pts undergoing massive volume replacement

  27. Hypothermia: Physiology • 32° to 35°C (89.6°–95°F) = “mild” hypothermia • Excitation (responsive) stage • Body attempts to retain & generate heat • HR, CO & BP all rise • Below 32°C (89.6°F) = moderate hypothermia • Slowing (adynamic) stage • Progressive slowdown of bodily functions & metabolism  • Decrease O2 utilization & CO2 production • Below 30° to 32°C (86°–89.6°F) - shivering stops

  28. Hypothermia: Cardiac • Dysrhythmias at Temp < 30°C (86°F) • Typical sequence: Sinus Brady -> slow AFIB -> VFIB -> asystole • Myocardium - extremely irritable • VFIB induced by rough handling of patient • Dysrhythmias:  Sinus bradycardia  AFIB or flutter  Nodal rhythms  AV block  PVCs  Ventricular fibrillation  Asystole

  29. Hypothermia • ECG Changes in Hypothermia: T-wave inversions PR, QRS, QT prolongation Muscle tremor artifact Osborn (J) wave • Osborn (J) wave: • Slow, positive deflection at the end of the QRS complex • Characteristic, not pathognomonic

  30. Osborn Wave

  31. Hypothermia Pulmonary: • Initial tachypnea -> decrease RR & TV • Aspiration pneumonia risk - Bronchorrhea & depressed gag reflex • ABG: false high PO2 and PCO2 & lower pH • Leftward shift of OxyHgb dissociation curve thus impairing O2 release CNS: • Depression of consciousness • SXS: Mild incoordination then confusion, lethargy & coma • Pupils may be dilated & non reactive

  32. Hypothermia Renal • Cold diuresis c resultant volume losses • Prone to rhabdomyolysis • Prone to ARF from myoglobinuria & hypoperfusion Hematology • Prone to intravascular thrombosis and subsequent embolic complications • Prone to DIC • Prone to bleeding

  33. Hypothermia: Diagnosis • Rectal Temp • Some standard clinical thermometers record only to 34.4°C (94°F) • Electronic thermometers with flexible probes can continuously monitor rectal, bladder or esophageal Temp

  34. Hypothermia:Treatment • ABCs • Cardiac Monitor, pulse Ox • Continuous or repeated Temperature recordings • Drugs: • IV thiamine 50 mg • If FSBS low: 50 to 100 mL of D50

  35. Hypothermia:Treatment • Rewarming: Active & Passive • Stable cardiac rhythm & Vitals: • Passive rewarming • Noninvasive Active rewarming: • Forced-air rewarming, warm O2 & warm IVF • Less than 30° (86°F) • Rapid rewarming until the temp is 30° to 32°C (86°–89.6°F) • Minimize dysrhythmias

  36. Hypothermia:Treatment • Passive rewarming:  1. Removal from cold environment  2. Insulation • Active external rewarming:  Warm water immersion  Heating blankets set at 40°C  Radiant heat  Forced air ( BEAR Hugger)

  37. Hypothermia:Treatment • Active core rewarming at 40°C: • Inhalation rewarming • Warmed, humidified air by face mask or ETT • Heated IV fluids • Warmed to 40°C (104°F) • GI tract lavage • Pulmonary aspiration if unprotected airway • Bladder lavage • Peritoneal lavage • Potassium-free dialysis solution at 104°–113°F • 2 catheters (instillation & removal)

  38. Hypothermia:Treatment • Active core rewarming at 40°C: • Pleural lavage • L thoracic cavity - heated fluid in proximity to the heart • 2 tubes – Instillation and removal • Extracorporeal rewarming • Pump-assisted cardiopulmonary bypass via femoral vessels is the most common • Right atrial–aortic bypass using a median sternotomy and heated hemodialysis • Mediastinal lavage via thoracotomy

  39. Local Cold Induced Injury • Frostnip: less severe than frostbite, no tissue loss, resolves with rewarming • Trench foot: cooling of tissue in a wet environment at above freezing temp over hrs to days • Chilblains(pernio): painful & inflamed lesions from chronic & intermittent exposure to damp non-freezing ambient temp

  40. Local Cold Induced Injury • First Degree Frostbite: superficial injury; edema, burning & erythema • Second Degree Frostbite: above + blistering • Third Degree Frostbite: involves full thickness skin & subdermal tissue • Fourth Degree Frostbite: involves above + subcutaneous tissue, muscle, tendon & bone • Cyanotic & insensate tissue, hemorrhagic blisters & skin necrosis • Later becomes mummified

  41. Local Cold Induced Injury • Treatment: • Chilblains & Trench foot: elevate, warm, bandage • Rx: Nifedipine 20mg PO TID, Topical steroids, prednisone, prostaglandin E1 • Frostbite: rapid rewarm with water at 42o C (107o F) for 10-30 minutes • Rx: Narcs, ibuprofen, aloe vera, PCN G 500,000 u PO q6 for 2-3 days • Debride clear blister • Don’t puncture Hemorrhagic blisters • NO DRY AIR REWARMING

  42. Heat Emergencies • Heat Exhaustion: • Sxs: malaise, fatigue, weakness, dizziness, syncope, HA, nausea, vomiting, myalgias, diaphoresis, tachypnea, tachycardia, orthostatic hypotension • Temp: elevated to normal • Sensorium and Neuro Exam: NORMAL • Dx Work-up: Check CK to r/o Rhabdo • TX: rest, evaporative cooling, IV fluids • Dispo: D/C except Electrolyte abnormalities or Co-morbidities

  43. Heat Emergencies • Heat Syncope: • Cause: volume depletion, peripheral vasodilation, decreased vasomotor tone • R/O other causes of syncope • Heat Cramps: • Painful muscle spasms of calves, thighs, shoulders • Cause: dilutional hyponatremia from replacement with free water • Heat tetany: • Paresthesias of extremities & circumoral area • Carpopedal spasms • Cause: respiratory alkalosis from hyperventilation

  44. Heat Emergencies: Heat Stroke • Difference from Heat exhaustion is Altered Mental Status & Definite elevated Temp • Core Temp 40 - 47o C • Neurologic Sxs: ataxia, confusion, bizarre behavior, agitation, Szs, obtundation & Coma • Risk Factors: Age <4 or > 75yo; CHF, psych illnesses, ETOH, dehydration, poverty, social isolation, poor conditioning, no access to air conditioning, poorly acclimated to warm weather, medications (B-Blockers, Ca Channel Blockers, Anti-cholinergics)

  45. Heat Emergencies: Heat Stroke • Diagnostic Work-up: CBC, Electrolytes, CK, LFTs, ETOH level, Tox Screen, Coags, UA, urine myoglobin, U preg, ABG, CXR, EKG • Differential Diagnosis: sepsis, meningitis, encephalitis, toxidromes (anticholinergic, PCP, salicylates, sympathomimetics), DKA, thyrotoxicosis, status epilepticus, stroke, neuroleptic malignant syndrome, malignant hyperthermia

  46. Heat Emergencies: Heat Stroke • Treatment: • ABCs • ETT if altered mental status, hypoxia or diminished gag reflex • Volume Replacement: dehydrated & prevent Rhabdomyolysis • Evaporative Cooling: disrobe pt; spray tepid water at patient via surrounding fans • Treat shivering with Benzodiazepines

  47. Heat Emergencies: Heat Stroke • Aggressive Cooling: immersion cooling, cold water gastric & urinary bladder lavage, thoracostomy lavage, cariopulmonary bypass • Seizures: treat with Benzos • Rhabdomyolysis: • IV hydration, furosemide 40mg IV, Na Bicarb • Hyperkalemia: normal protocol • Admission: ICU

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