Presentation on theme: "Environmental Emergencies Part 1 Wilderness Emergencies"— Presentation transcript:
1 Environmental Emergencies Part 1 Wilderness Emergencies Emergency Medicine Clerkship SeriesAuthor: Todd A. Parker, M.D.Co-author: Tom Bottoni, M.D.
2 Vacation! You get that much needed time off Your significant other wants to go to St. TropezBut you really want to climb Mt. McKinley (Denali)Highest peak in North America-20,320 ft!She decides to give it a try, and you’re off!4 days into the climb, you are at camp 4000 ft from the summit, and she complains of a headache and is confused…..
3 High Altitude Sickness Definitions: - Moderate altitude ft- High Altitude- Extreme High Altitude >18000Can occur at altitudes greater than 5000 ftAlthough most occur above 11,500 feetInfluenced by:- Rate of ascent - Final altitude - Sleeping altitude - Duration at altitude
4 Who is at risk? Hard to predict who will get it! Higher risk Younger > OlderMales > FemalesExcept during water retaining phase of cycle (premenses)Persons with previous high altitude illnessCan occur in previously unaffectedThose with previous illness can be unaffectedPersons who overexert themselvesPhysical fitness not necessarily protectiveSmoking, Alcohol, Sedatives
5 Physiology Hypoxia due to ↓ in barometric pressure Hypoxemia due to ↓ PO2 of inspired airImpact on cell variableAbility to acclimatize/compensatePre-existing medical conditions
6 Acclimatization Ventilation – increases almost immediately CardiovascularIncreased Cardiac Output (CO)Increased pulmonary perfusionImproves V/Q mismatchesIncrease in cerebral blood flowHematologicRelative increase in Hg due to diuresesErythropoietin – stimulates bone marrowEffect takes weeks
7 Types of illness Altitude-exacerbated conditions NOT the focus of this talk, but be aware!Congenital Heart DiseasePulmonary HypertensionCoronary Heart DiseaseCHFSickle Cell Disease / TraitObstructive Sleep ApneaPregnancyRadial Keratotomy (Corrective Eye Surgery)
9 Acute Mountain Sickness Defined as headache and one or more of:- Anorexia - Fatigue/weakness- Nausea/Vomiting - Difficulty Sleeping- Dizziness - LightheadednessDevelop 6-10 hours after ascentMay be <1 hrUsually Self Limiting
10 AMS - Treatment Rarely need to descend – slow / halt ascent Analgesics/antiemetics prnConsider acetazolamide ( mg BID)Speeds acclimatizationDescend if sx do not improveDexamethasone 4mg PO/IM if unable to descendGraded ascent is best preventive measure (600m/day)
11 High Altitude Cerebral Edema (HACE) AMS – Sx progress to global cerebellar dysfunctionAtaxia or altered mental statusVertigo, Diplopia, rarely seizuresUsually > ft (have occurred as low as 9K)Begin 12 hrs or greater after onset of AMSSx usually globalIsolated focal sx – concern for CVA/TIA
12 HACE - Treatment Immediate descent definitive tx Supplemental O2 (highest flow or sats >90%)Dexamethasone 8mg PO/IM then 4mg Q6hIf cannot descend, hyperbaric therapy (more later)
13 High Altitude Pulmonary Edema (HAPE) Non-cardiogenic pulmonary edemaAccounts for most high altitude deathsOccurs 1-3 days after arrival at altitudeRarely occurs after 4 days – consider alternative dx1-2% of high altitude climbers15% of those with rapid ascent
14 HAPE Pathophysiology Hypoxia leads to pulmonary artery HTN Increased pulmonary vascular resistanceHowever, occurs in everyone – not just HAPEPulmonary capillary pressure increasesLeads to overperfusion Capillary leakageFluid as well as proteins leak out Exudative fluidWith descent, pressure decreasesCapillaries “reseal”, leakage stops RecoveryInflammatory mediators likely not primary process, but secondary to leaked proteins
15 HAPE Treatment Descent! Supplemental O2 B-agonists: Decreases pulmonary artery pressure up to 50%B-agonists:Increase fluid clearance from alveolar spacesNo role for dexamethasoneLimited role for acetazolamide (may dyspnea)
17 Hyperbaric therapy Greatest benefit in HACE HAPE – likely beneficial Use highest PSI availableHAPE – likely beneficialCost – benefit vs. Supplemental O2 generally precludesAMS – little additional benefit
18 HAI - Summary Medications: Stop ascent – attempt acclimatization Supplemental O2 immediately if availableIf no improvement or worsening, descendMedications:Acetazolamide – best for acclimatizationLittle benefit in acute tx (no use in HAPE)DexamethasoneAMS and HACENo role in HAPEB-agonists useful in HAPENifedipine – likely beneficial in HAPEUse with extreme caution if concomitant concern for HACE
19 Recovery!With rest and oxygen, your significant other has recovered at base campNow armed with more knowledgeBegin ascent againYou’re at camp 4000 ft from the summit again, and a storm hits – you’re stuck!That night, she says that she can’t feel her fingers…
21 Frostbite Skin blood flow ↓ when skin temp < 140 C (57.20 F) “Hunting Response” – alternating cycles of vasodilation and vasoconstriction at < 100 C (500 F)Vasodilation brings cooled blood to coreAs core body temp drops, cycles end and blood flow completely cut to extremitiesTissue freezes – ice crystals form when temp 00 CCreates osmotic gradient pulling fluid from intracellular spacesIntracellular NaCl rises, proteins denature, membranes failReperfusion injuries – hours to days
22 Frostbite Classification 10: Non-sensate white area/surrounding erythema20: Vesicles with surrounding erythema30: Hemorrhagic blisters with eschar formation40: Necrotic tissue, involves muscle/tendon/boneReclassification – Superficial (First/Second) and Deep (Third/Fourth)Classified according to treatment/outcome vice tissue involved
23 Frostbite Treatment Thawing stage Consider delay if: Adequate analgesia not availableDelayed evacuation (i.e. ambulation required)Remove wet/constrictive clothingRapid rewarmingUse C water for minutes with motionAvoid hot untested tap water - risk of thermal burns!Avoid massaging and dry heatParenteral analgesics
24 Frostbite Treatment Post-Thawing Treatment Debride CLEAR blisters Apply aloe skin cream (Dermaide)Do NOT debride hemorrhagic blistersElevate affected partsTetanus prophylaxisScheduled ibuprofen / prn narcoticsPen G 600,000 units q6hDaily Hydrotherapy at 400 C for minsNo Smoking!
25 Foiled! She recovers from her mild frostbite Since your flight home isn’t for 10 days, you propose another summit attempt, and get this look…
26 Plan BOn second thought, you propose camping in beautiful Denali National Park to view the Northern Lights…You fall asleep, under the lights, after sharing a couple bottles of wine togetherYou wake up a few hours later and you notice she is shivering violently and you have a hard time waking her…
27 Accidental Hypothermia Definition: Core Temp < 350 C (950 F)Mild: 320 C – 350 C (89.60 F – 950 F)Moderate: 280 C – 320 C (82.40 F F)Severe: <280 C (82.40 F)
28 Mild Hypothermia 320 C – 350 C (89.60 F – 950 F) Signs / Symptoms: ShiveringTachypnea / Tachycardia / HypertensionAtaxia / DysarthriaLoss of fine motor coordinationConfusion / lethargy
29 Moderate Hypothermia 280 C – 320 C (82.40 F - 89.60 F) Signs / Symptoms:Shivering StopsBradycardiaOsborn (J) waves on EKGAltered Mental StatusSlowed ReflexesCold DiuresisPupil Dilation
30 Severe Hypothermia <280 C (82.40 F) Signs / Symptoms: Unresponsive / ComaHypotensiveV Fib / AsystoleAcidemiaLoss of reflexes
31 Lab Tests (if able) BMP – pay attention to electrolytes (esp K+) CBC – Hct increases 2% for each 10 C dropTrauma – normal Hct may mean blood lossABG – interpret as is (blood rewarmed in lab)Coags: May be normal - blood is rewarmedDo not necessarily reflect physiology in patientOther labs as indicated if another underlying cause o hypothermia suspectedEtOH/UDSCardiac Enzymes, etc
32 Hypothermia Treatment Large Bore IV(s) – Bolus with warm fluidsIntubate if indicatedImmediate Actions – ACLS!Check Vital Signs and ECGCheck seconds for pulse – difficult to detectRectal thermometer – must be low temp capableStandard thermometers only to C (940 F)If no pulse, begin CPRControversial in severe hypothermia, however likely beneficial
33 Hypothermia Treatment Most dysrhythmias convert on rewarmingA. Fib/FlutterSinus bradycardiaTransient ventricular dysrhythmiasV. Fib / V. Tach – defibrillate at 1-2J/kgOne shock onlyMay be ineffective at temps < 300 CIf fails, reattempt after each degree rise
34 Hypothermia Treatment Intravenous drugsMay be ineffective below 300 CGive at longer intervals above 300 CAmiodarone drug of choice for V. FibAvoid procainamide – may worsenIf EtOH – Replete glucose and thiamineHypoglycemia and Wernicke’s may help precipitate hypothermia
35 Rewarming Cornerstone of treatment – REWARM! Rapid rewarming to 30 degreesMinimize risk of dysrhythmiasOnce above 30 deg, can slow rewarming rateCardiovascular status is most important
36 Passive Rewarming Ideal method: Slow, physiologic Must have intact thermoregulationShivering intactCaution in underlying diseasesLikely only effective in mild hypothermiaMethods:Remove from environmentRemove wet clothesBlankets
37 Active External Rewarming Use for moderate hypothermiaMonitor closely!Rapid peripheral vasodilationMay return cooled blood to coreLikely not clinically significantConsider rewarming trunk aloneWarm water immersion – ensure monitoringHeating blanketsForced air (BAIR Hugger)Radiant heat
38 Active Core Rewarming ALL Patients Warmed IV Fluids Warmed humidified OxygenSmall heat gain – mostly prevents further heat loss
39 Active Core Rewarming Severe hypothermia/cardiac instability Lavage with warm fluids - Nasogastric/rectal Pleural (via thoracostomy)Bladder (via Foley) Peritoneal (via DPL catheter)Mediastinal Lavage via open thoracotomyIf availableCardiopulmonary BypassHemodialysisSet up difficult, but most effective!
40 That’s it!Although she recovers uneventfully, she’s had it with this cold weather vacation!You’re on the next flight for HawaiiThat afternoon, after landing, she decides to unwind by going for a run2 hours later she hasn’t returned, you drive out to find her and she’s sitting on the side of road…
41 Heat Emergencies Predominant forms of heat loss Causes: Radiation (65%): loss via electromagnetic wavesOnly occurs if temperature differential (stops at 950 F)Evaporation (30%): transfer of heat via sweat and saliva evaporationMinimal if humidity > 80%Causes:Increased internal heat productionIncreased external heat exposureImpaired heat dispersion
42 Increased Internal Heat Physical ActivityExerciseSeizuresCombative behaviorPharmacological agentsAmphetamines, cocaine, LSD, PCPEndogenous FeverNOT the same as environmental hyperthermiaShould not be exogenously cooled
43 Increased External Heat High Ambient TempsMinimizes radiation heat lossHigh HumidityMinimizes evaporative heat lossDirect exposure to sunlight
44 Impaired Heat Dispersion CV diseaseImpaired circulationImpaired compensationObesityAdipose - decreased vascularityInsulates the bodySkin alterationsClothingMedicationsAnticholinergicsCardiovascular drugsDiureticsSympathomimeticsPhenothiazinesAlcohol/DrugsExtremes of AgeDehydration
45 AcclimatizationIncreases ability to provide peripheral blood flow, protect kidneys, and increase sweatingImproved physical condition = improved cardiac response to vasodilationIncreased efficiency at shunting blood from non-critical areasIncreased activation of renin-angiotensin-aldosterone systemEnables increased sodium retentionExpansion of plasma volumeSweat glands increase sweat production
46 Heat Emergencies Minor heat illnesses Heat Exhaustion Heat Stroke Head EdemaHeat RashHeat SyncopeHeat CrampsHeat ExhaustionHeat Stroke
47 Heat Edema Cutaneous vasodilation and orthostatic pooling Resolves spontaneouslyIf treatment institutedRemoval from heatElevation of legs with support hoseDo not use diureticsDehydration more riskyMay cause electrolyte disturbances
49 Heat Syncope Secondary to Treatment Peripheral vasodilation Decreased vasomotor toneVolume DepletionTreatmentRemove from heat sourceOral or IV fluidsRest
50 Heat CrampsUsually secondary to electrolyte disturbances from sweatingDehydration or water-only rehydrationHyponatremiaHyperkalemiaTreatmentRemove from heatOral hydration with electrolyte containing fluidsIV fluids
51 Heat Exhaustion Signs and Symptoms: Non-specific! Temp usually elevated but < 410 CFatigue/weakness/dizziness /syncopeNausea/vomitingHeadachesMyalgias and muscle crampsTachycardiaPiloerectionProfuse sweating usually present
52 Heat Exhaustion - Treatment Remove from heat and minimize activityCool with fans/ice packs to neck, groin, axillaeOral rehydration w/electrolyte containing fluidsIV Fluids if not alert or nausea/vomitingReplace fluids over several hoursMonitor vital signsUrine outputOrthostatics
53 Heat Stroke Signs and Symptoms Elevated Temp – usually > 410 C (1060 F)Hyperdynamic cardiac parametersTachycardia/TachypneaIncreased systolic / increased pulse pressureCNS Dysfunction- Seizure - Delirium - Cerebellar dysfunction- Coma - Hallucinations - Pupil dysfunctionOliguriaAnhydrosis – often present but not required!
54 Heat Stroke - Treatment Initial resuscitationABC’s, IV access, cardiac/pulse ox monitoringRectal thermometer for continuous monitoringIntubation if indicatedBegin IV fluid boluses (Normal saline or LR)Place foley and NG TubeRapid Cooling is key
55 Cooling Techniques Goal is 38-390 C to avoid overshoot Evaporative cooling preferredRemove clothing, spray with lukewarm waterUse large fans to blow air across skinImmersion – rapid cooling in ice waterDifficult to monitor patientMay cause shiveringVery uncomfortable if awakeInternal cooling (lavages – i.e. bladder, gastric)Effective, but probably unnecessaryCP bypass – likely not worth risks
56 Adjunct Therapies Antipyretics – NO ROLE! Benzodiazepines May interfere with endogenous thermoregulationBenzodiazepinesHelp reduce agitation / shivering / seizuresEtOH / Drug withdrawalAvoid large volumes of IV fluidMay lead to pulmonary edema (even healthy pts)Except in rhabdomyolysisRenal failureHemodialysis if unresponsive to fluids / acid-base correction
57 Fortunately…She just has a mild case of heat exhaustion. You get her water and into your air conditioned vehicleBack at the hotel, after she’s rested for a couple hours, she decides to go for a swim in the oceanYou tell her you’ll meet her out there in a minuteYou lose track of time watching a great ER rerun, and 30 minutes later you arrive to find several lifeguards carrying her inApparently a rip tide pulled her under, and it took the lifeguards several minutes to pull her out…
58 Submersion Injuries Drowning – Death within 24 hours of submersion Near Drowning – survival after submersion injuryThird leading cause of accidental deathFreshwater > SaltwaterEtOH/Drugs commonly involvedMost victims children/ adolescents
59 Submersion Injuries Sequence: Breath holdingPanicSwallowing water / emesisBreathing water“Dry drowning” – laryngospasm/glottic closureFinal common pathway - hypoxemia
60 Pulmonary Injuries Fresh Water Salt Water Inactivates surfactantAtalectasis and loss of pulmonary complianceSalt WaterOsmotic gradient pulls fluid into alveoliIntrapulmonary shunting / VQ mismatchIf survive initial aspiration – ARDS or pneumonia
61 Signs/Symptoms 4 categories Asymptomatic Symptomatic Altered mental status / anxietyHypothermia/Tachycardia/BradycardiaAny dyspnea, no matter how slightCardiopulmonary ArrestObviously DeadNormothermicAsystoleNo neurologic response
62 Submersion – Labs/Studies ABG essentialCBC, BMP, Lactate, CoagsFollow creatinine – renal failure delayedEtOH / UDSChest X-rayCT Spine / Head CT if at risk for injuryC-Collar until cleared by mechanism or studies
63 Submersion Treatment Pre-hospital Unless certain, assume spinal injury C-Collar and backboardMaintain precautions when movingRescue breathing and supplemental O2CPR – start on almost all patientsIn water chest compressions generally worthlessBegin rewarming
64 Submersion Treatment -ED Unless obviously dead, assume survivabilityEspecially childrenIntubate if unable to oxygenate/ventilatePEEP - Improves ventilation and volumeShifts fluid into capillariesConsider BIPAP if awakeIf intubated, perform bronchoscopyACLS algorithms if indicatedRewarm patient (as per hypothermia protocols)
65 Complications ARDS Pneumonia Disposition/Treatment Supportive care Direct water aspirationAspiration of gastric contentsContaminants / organisms in waterBacteria and fungi common, esp warmer watersDisposition/TreatmentMost need admission, ICU if warrantedProphylactic antibx / antifungals not necessary, unless sxExtended spectrum PCN / B-lactamase + aminoglycosideIf asymptomatic and no injuries, observe and discharge
66 Turns out she’s OKYou decide that you’ll go back in the water, together, but this time with scuba tanks to check out a nearby reefAfter enjoying a beautiful dive, you begin your ascent to the surfaceSuddenly, a large jellyfish stings her, she panics and races for the surfaceYou remember your dive tables, and ascend as rapidly as you can, safelyAt the surface, she seems to be doing OK but is complaining of severe leg pain (where she was stung) as well as itchy skin and right shoulder pain….
67 Diving Injuries / Dysbarism Sea level – ambient air pressure = 1 atmAscending - ambient pressure halves at ftDiving – ambient pressure increases by 1 atm every 33 feet!Boyle’s Law – pressure/volume inversely proportionalAs pressure increases, volume decreases (diving)Vice versa (ascending)Henry’s Law – gas enters liquid in proportion to partial pressureAs descend, partial pressure increases – gases more solubleDuring ascent, gases come out of solutionOxygen metabolized, nitrogen does notCoalesces into bubbles if ascent too quick
68 Types of Injuries Barotrauma of descent Barotrauma of ascent Direct barotraumaArterial gas emboli (AGE) / Dysbaric air embolism (DAE)Indirect effects of ascentNitrogen NarcosisDecompression Sickness
69 Descent Barotrauma (“Squeeze”) Ear SqueezeExternal (Barotitis Externa)Air trapped in ext canal compressesTM bulges outTrauma to TM and surrounding external canalMiddle (Barotitis Media) – most common!Cannot equalize air in middle earTM bulges inward – may ruptureMay cause trauma to ossicles/ round windowInner (Barotitis interna)Trauma to round windowAir enters inner earClassic triad – tinnitus, hearing loss, vertigoAlso nausea/vomiting, ataxia, nystagmus
70 Descent Barotrauma (“Squeeze”) Sinus SqueezeAir trapped in sinusesCauses pain / hemorrhage into sinuses epistaxisTreatment of ear and sinus squeezeDecongestants (oral and nasal spray)Antibiotics if TM ruptureAnalgesiaAvoidance of divingMask SqueezeMust equalize pressure behind mask during descentCan cause localized petechiae /conjunctival hemorrhage
71 Ascent Barotrauma Reverse process of squeeze Occurs from gas expansion Normally gas escapes into atmosphereIf escape blocked, barotrauma
72 Ascent Barotrauma (cont) Ears and sinuses – usually not affectedIf air got in on descent, can get outBarodontalgia (“Tooth Squeeze”)Descent - compressed air gets in fillings/decayAscent – expandsCannot escape PainGI Barotrauma (Aerogastralgia) - air trapped in GI tractSwallowing air (improper valsalva)Drinking carbonated beverages or heavy meal priorGenerally self-limiting pain/discomfort – rupture rareIf pneumoperitoneum, also consider GU source (esp females)
73 Pulmonary Barotrauma Most severe barotrauma of ascent Air normally breathed outequalizes pressureIf air not breathed out, expandsRuptures into surrounding tissuePneumomediastinum and SubQ emphysema commonUsually self-limitingPneumothorax and Arterial Gas EmbolismRequire interventionPneumothorax – needle decompression / thoracostomy
74 Arterial Gas Embolism Rupture of alveolar air into pulmonary veins Air embolism left heart systemic circulationSymptoms of thromboembolic diseaseCVA type symptoms or myocardial infarctionAny sudden, severe symptoms of thromboembolism on ascent should be treated as AGEImmediate recompression/hyperbaric treatmentResuscitate per ACLSPosition right lateral decubitis or supineDo not place head down – cerebral edema
75 Nitrogen NarcosisNitrogen – increased solubility at increased partial pressures (remember Henry?)Intoxication effect at high partial pressureMost feel effect by feetImpaired >200 ft, unconscious >300ftEffects reverse with ascentCan precipitate other errorsImpairs recollection of dive / ascent – impairs history
76 Decompression Sickness (DCS) Dissolved nitrogen forms bubbles if ascent too rapidDirect effect of bubblesIndirect effect of inflammatory response to bubblesCauses activation of clotting/inflammatory cascadesNet effectDecreased tissue perfusionIschemic injury
77 Type 1 DCS “Niggles” – mild pains, begin to resolve ~ 10 mins Pruritis (“Skin Bends”)Skin rashLymphatic involvementPeripheral edemaPain (“The bends”)Aching painUsually in joint, tendon, occasionally muscleShoulder most commonly affected
78 Type 2 DCS Pain uncommon (30%) Neurologic system Nitrogen very soluble in fat – myelin sheathSpinal cord most commonly affected (esp lower)Bladder dysfunctionPulmonary DCS (The “Chokes”)Venous nitrogen emboliChest pain, cough, dyspnea, pulmonary edemaCan progress to hemoptysis
79 Physical Exam In addition to vital organs, pay close attention to Sclera / retinaTympanic membranesThorough neurologic examUrinary retentionDifferentiating AGE from DCSLength of dive (must be longer dive to develop DCS)Time of onset (AGE rapid / DCS delayed)AGE – only CNS effects are on the brain
80 DCS Treatment Prehospital Extricate from water / immobilize if trauma Supplemental O2May result in resolution of mild DCSASA for anti-platelet activityConsider in-water recompression only if in remote locationCPR if indicatedNeedle decompression of tension ptxAvoid trendelenburg
81 DCS Treatment ED care All of the prehospital measures apply 100% O2 – intubate if warrantedAggressive fluid resuscitationGoal UOP is 1-2ml/kg/hrTreat nausea and headachesArrange transfer to HBO facilityConsider even if improvement in symptomsRelapses / worsening occurEnsure air transport can maintain pressurization!
82 She recovers (again)Supplemental oxygen and about 30 minutes of rest, and she’s feeling betterBut what about that jellyfish sting?
83 Marine Envenomations~1200 species of venomous or poisonous marine animals worldwideFew cause major medical issuesBroad array of speciesVarious neurotoxic and proteolytic venomsUsed for paralyzing / killing preyHumans are often accidental victims or hosts
89 Marine Envenomation -Treatment Cornerstones – ABC’s First!Detoxify venom – rinse with normal salineFreshwater may activate venomPain and symptom relief – narcotics, antihistaminesLocal wound careFB removalDeactivation and removal of attached nematocysts5% acetic acid / isopropanol (further deactivate)Apply baking soda slurry or shaving creamAllow nematocysts to coalesce and scrape offMay remove with adhesive tapeMarine wounds prone to infectionAeromonas, Vibrio, Pseudomonas, Erysipelothrix sppProphylactic antibiotics for serious wounds
90 She’s had it with the ocean! You make one last attempt to salvage your vacation, and let her pick the spotShe wants as far away from the ocean as possibleOff to the Grand Canyon!
91 First night of campingYour significant screams, and you wake up to see this guy in tent!
92 Land Envenomations Meanwhile, her hand begins to swell rapidly and goes numb as the wound site oozes blood, and she starts to get nauseated and dizzy…
93 Snake Envenomations Poisonous or Not? Exception: Coral Snakes (Elapidae)
94 Epidemiology 14 Families of snakes 3 main poisonous snake families ViperidaeVipers and Pit VipersRattlesnakesElapidaeCobras and MambasCoral SnakesHydrophidae – Sea snakesColubridae – Asps and Mole Vipers~4000 snake bites annually reported in USA<20 deaths / year
96 Components of Poisonous Venom Fibrinogenases, phospolipasesPlatelet aggregation inhibitorsEnzymes with hemorrhagic activityNumerous other uncharacterized proteinasesNeurotoxins (for coral snake venom)
97 Crotalid Envenomations None (dry bites) - ~15-20%Mild - local swelling and painNo systemic featuresModerate – progression of swellingLocal tissue destructionHematologic abnormalitiesSystemic sxSevere – marked swellingBullae and tissue necrosisShockCoagulopathy
98 Crotalid Envenomations – Initial Management Immobilize injured part at or below heart levelProvide local wound careCleansingDebridementProphylactic ABXTetanusLab evalCBC, CMP, CPKCoags and DIC panelObserve for 24h or admit, for sx of progressionConsider antivenin early, for mod / severe envenomations
99 Role of AntiveninsNeutralizes circulating venom toxins when given early (<6H)Can mitigate local tissue destructionSlows/prevents coagulopathy and systemic sxActive against:US rattlesnakesCopperheads, and cottonmouthsSome sea snakesSeparate antivenin for coral snakesNo dose adjustment for childrenDose is based on venom load, not subject weight!Call local poison control center
100 Crotalid Antivenin Indications for Antivenin Rapid progression of sxs Significant coagulopathyProfound thrombocytopeniaHemodynamic compromiseNeuromuscular toxicityContraindications for AntiveninHypersensitivity to horse or sheep serumHypersensitivity to papain or papayaPoorly controlled atopyConcurrent beta blocker useMay worsen anaphylaxis
102 Desert Scorpion – in attack posture! ScorpionsNumerous venomous species worldwideSeveral species native to US southwestOnly Centruroides bark scorpions have a poisonous venomCentruroides spp are indigenous to AZ and CANatural LightUV LightDesert Scorpion – in attack posture!
103 Scorpion Venom Components Numerous digestive enzymesHyaluronidasePhospholipasesNeurotoxinsStabilizes Na+ channels in open positionCauses overfiring of N-M junction and autonomic nervous system
104 Clinical Presentations Most encountersLocal, immediate pain and inflammationSubsequent paresthesiasSx often resolve in several hours with local wound and sx careOther symptoms (children at much higher risk)Diplopia and nystagmusMuscle fasciculations, seizures, and paralysisRarely, cardiovascular collapse and resp failureEven rarer, pancreatitis
105 Scorpion Sting Management Local wound care & irrigationTetanus prophylaxisBenzos for sedation/muscle spasm controlSevere envenomationSupport ABC’s and hemodynamicsConsider antivenin in consult with Poison Center
106 Spider Bites 50,000 spp of spiders in USA Most possess paired poison glands attached to jaw like fangsFew poisonous spiders capable of penetrating human skinPredominant Poisonous Spiders in USALatrodectus (black widow)Loxosceles (brown recluse)Tarantulas (none in US are poisonous)Localized wound effects – systemic effects very rareIf indigenous area, may not be just an abscess!
107 Poisonous Spiders Brown Recluse (Loxosceles) Black Widow Spider (Latrodectus)
108 Spider Venom Components LoxoscelesDigestive enzymesCollagenases, proteases & phospholipasesSphingomyelinase DCytotoxic & hemolytic agentLocal tissue necrosisLatrodectusDigestive enzymesAlpha latrotoxinBinds to synaptic receptorsCa+ channel dysfunctionRelease of Ach with motor end plate stimulation
109 Black Widow – Clinical Presentation Local puncture woundCentral clearing and outer ring of erythemaPainful within 30 minPainful muscle crampsFasciculations follow in 3-4hBoard like rigid abdomenResembles an acute surgical abdomenComplications (rare)Diaphoresis, nausea/vomitingSevere HTNCardiorespiratory collapse
110 BWS Bite - Management Local wound care Tetanus 6-8h observation – supportive interim careIV calcium and benzos to treat muscle crampingNarcotic pain controlConsider Latrodectus antivenin
111 Latrodectus (Black Widow) Antivenin Equine derived antiveninSmall risk of anaphylaxisIndicationsSevere envenomationsElderlyCardiac pts not responding to supportive carePregnant patients- prevent preterm labor
112 Loxosceles (Brown Recluse) Envenomations Immediate painful burning sensation at siteHemorrhagic central vesicle/bulla with surroundingGives way to a necrotic ulcer over next 48-72hSlow to heal (can last a >month)Rare complicationsIntravascular hemolysisDICSecondary infectionsDifficult Dx – resembles many other disorders
113 Brown Recluse - Management Local wound careTetanusDapsone – attenuation of necrotic ulcer formationNot clinically born outHyperbaric OxygenGoat derived antivenin, but not FDA approved for useAvoid surgery if possibleMost heal without surgical intervention
114 Solenosis (Fire Ants) 5 native spp of Solenosis in USA 2 spp imported via Mobile, ALHave spread throughout gulf basin / west to AZ,/CAOne nest can produce 200,000 ants!Swarm and attack en masse when provokedCross reactivity of fire ant venom with Hymenoptera venomsSystemic sx in susceptible individuals
115 Fire Ant VenomSimilar to Hymenoptera venoms of bees, wasps, hornets and yellow jacketsBiogenic aminesAch, histamine, dopamine, serotonin)Proteases and alkaloidsHyaluronidase, phospholipase)Fire Ant Nest
116 Clinical Presentation Numerous papules at site of bitesLocal urticaria, pruritus & angioedemaSystemic anaphylaxis in susceptible persons
117 Fire Ant Bite Management Local wound careTetanusRemoval of stingers & attached venom sacsTopical papain (meat tenderizer) to inactivate venom proteinsH1 & H2 blockers, steroids, analgesicsTx of Anaphylaxis, airway management and hemodynamic support, where indicated.
118 It’s A Dangerous World Out There! Now you’re better equipped to handle itPrevention is the most important step in treatmentAnd your significant other?She leaves you to be with someone much saferLike a stuntman or explosives handling expert
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