Upload
neil-brown
View
215
Download
0
Tags:
Embed Size (px)
Citation preview
IRON and STINGS
Rob Hall
Dr. M. Yarema
June 20th, 2002
GOALS
• IRON– recognize dx
– explain pathophysiology
– know how, when and why to treat
• STINGS– know the basic
management of bee/wasp/fire ant stings
– know the approach to management of marine bites, stings, and nematocysts envenomations
She got into my pills……..
• 3yo female - 10 kg
• 5 pills of Ferrrous sulphate 325 mg gone
• Presents early vomiting blood
• Are you worried?
• What if it was 10 pills?
Toxic Ingestions
• Depends on ELEMENTAL IRON
• Look up % elemental iron in ingested tab
• Ferrous sulphate (20% elemental Fe + 10kg child)– 325 mg X 0.20 = 65 mg elemental Fe– 65 mg X 5 pills = 325 mg ----> 32 mg/kg– 65 mg X 10 pills = 650 mg ----> 65 mg/kg
TOXICITY
• Elemental Fe Peak [] Toxicity– < 20 mg/kg < 30 umol/L none– 20 - 40 mg/kg 30 - 60 mild– 40 - 60 mg/kg 60 - 90 mod– > 60 mg/kg > 90 umol/L severe
LOCAL TOXICITY
• Direct GI corrosive/irritant
• Nausea, vomiting, abdominal pain, diarrhea, hematemasis, melena, hematochezia
• Must consider on ddx of gastroenteritis, GI bleed in peds
SYSTEMIC TOXICITY
• Coagulopathy (inhibits thrombin formation)• Liver toxicity (periportal necrosis)• Increased Anion Gap Metabolic Acidosis
– Inhibits oxidative phosphylation ---> lactate– Direct negative ionotropy ---> lactate– Direct vasodilation ---> lactate
• MUST be on ddx of SHOCK and AGMA NYD
What causes the increased AGMA in Fe overdose?
• Fe 2+ ----------------> Fe 3+ and Hydrogen
• Anerobic metabolism ---------> lactate
• Hypovolemia from V/D --------> lactate
• Hypovolemia from GIB ---------> lactate
• -ve Ionotropy ---------------> lactate
• Vasodilation ----------------> lactate
FIVE STAGES
• STAGE I (< 6hrs): GI signs symptoms
• STAGE II (6 - 24hrs): Latent period
• STAGE III (variable): Systemic toxicity
• STAGE IV (2-3 days): Liver failure
• STAGE V (weeks): Gastric outlet obstruction
Complications
• Yersinsia enterocolitica– Noted increased rates of infection– Iron as a growth factor– Increases with deferoxamine use– Abdo pain, fever, diarrhea, sepsis
LABS
• ? WBC > 15 and Glucose > 7.5 – may be a bad sign but not reliable
• Increased AGMA– remember ddx: AMUDPILECAT
• TIBC– theoretical reassurance if Fe level less than
TIBC b/c enough transferrin around to bind– NOT reliable; DO NOT USE or MEASURE
IRON LEVELS
• Measure at 2 - 6 hrs (Peak 4hrs usually)
• Repeat levels to catch peak (?)
• Normal is 14 - 32 umol/L
• Goes down town; turn around in 2hrs but must notify lab of STAT order
• Levels used to help guide therapy
• Falsely lowered in presence of deferoxamine thus must do before
AXR
• Radiopaque• Liquids and
chewables are NOT radiopaque
• Absence on AXR does NOT r/o ingestion
• Ddx of radiopaque ingestant– C ca carbonate, chloral hydrate
– H heavy metals (iron, zinc, ba, Li, bisthmus)
– I iron
– P KCl, Play-doh
– P phenothiazines
– E enteric coated pills
– D dental amalgan
DECONTAMINATION
• NO ipecac
• Doesn’t bind charcoal
• Gastric Lavage– Indicated if visible in stomach on AXR– Water or saline NOT bicarb, phosphosoda, Mg
• Whole Bowel Irrigation– Indicated if visible past stomach on AXR
DEFEROXAMINE
• Specific iron chelator
• Derived from Streptomyces pilosus
• Ferric iron + deferoxamine -----------------> ferrioxamine (colors urine red/brown)
• Chelates free iron in blood and intracellular
DEFEROXAMINE
• Administration– iv > im > po– iv indicated – goal is 15 mg/kg/hr– start at ? 5 mg/kg/hr and increase to target
DEFEROXAMINE
• Adverse Effects– Hypotension with rapid administration– ARDS (more common with higher doses, longer
administrations > 24hrs)– Increased Yersinsia infections– Ocular and Ototoxicity have been reported with
chronic administration– Deferoxamine is NOT contraindicated in
pregnancy
DEFEROXAMINE CHALLENGE
• 90 mg/kg im and see if urine color changes
• +ve = urine color change -----------> tx
• -ve = no urine color change --------->no tx
• Problems– shown to be UNRELIABLE– DO NOT use as sole determinant for basis of
treatment
Vin Rose’
DEFEROXAMINE
• Indications for use– Ingestion of > 60 mg/kg– Iron level > 90 umol/L– Systemic toxicity: hypotension, coma, AGMA,
seizures
• Discontinuation (generally at 24hrs)– Clinically well– AGMA resolved– No further urine color change
OTHER Mx
• Deferiprone– Oral active iron chelator– Used in chronic setting; being looked at with
acute ingestions
• CAVH– Infuse deferoxamine on arterial side; dog
studies– Essentially experimental at this point
DISPOSITION
• Asymptomatic after 6 - 8 hrs rules out significant ingestion and d/c home
• Management of moderate to severe ingestions depends on …….– Clinical assessment: hx, physical, labs– Amount ingested: > 60 mg/kg is bad– Iron level: > 90 umol/L is bad
APPROACH
H is to ryP h ys ica l
L ab s
M IL D< 2 0 m g /kg
asym p tom atic
M O D E R A TE2 0 - 6 0 m g /kg
u n kn ow n am ou n t"m ild " G I s /s
S E V E R E> 6 0 m g /kg
"severe" G I s /s A G M A or S h ock
D ete rm in e S everity
MILD
• < 20 mg/kg and asymptomatic
• Management– Observe 6-8 hrs– D/C if asymptomatic– No iron levels necessary
MODERATE
• 20 - 60 mg/kg or unknown + “mild”GI s/s
• Order AXR and Fe level (2-6hr)
• Consider Gastric lavage or WBI
• Fe level < 60 or 60 - 90 and asymptomatic -------> observe 6 - 8 hours and d/c if well
• Fe level > 90 or 60 - 90 and symptomatic -------> treat as severe
SEVERE
• > 60 mg/kg, severe GI s/s, AGMA, shock• AXR, Fe level, baseline urine• Gastric lavage or WBI based on AXR• Start Deferoxamine: target is 15 mg/kg/hr• Discontinue Deferoxamine when……
– Clinically well– AGMA resolved– No further urine color change
The GOODs on IRON
• LOCAL and SYSTEMIC toxicity: 5 stages
• Asymptomatic at 6hrs r/o sign. ingestion
• Consider with gastro, GIB, AGMA, shock
• Absence of pills on AXR does NOT r/o
• Rx based on clinical status, amount ingested, and iron levels
• Don’t wait for iron level if toxic
HYMENOPTERA
• Nasty arthropods: bee, wasp, hornet, yellow jacket, fire ants
• 2nd most common cause of anaphylactic deaths
• Killer Bees: “normal” bees with a mean streak (not more toxic, just more aggressive)
HYMENOPTERA REACTIONS
• Local– pain, erythema, edema, swelling, itching– lasts hours to days; looks like infection
• Toxic– N/V/D, lightheaded, syncope, H/A, fever,
muscle spasms (NO urticaria or bronchospasm)– Due to toxic nature of venom NOT anaphylaxis– Lasts few hours to 2-3 days
HYMENOPTERA REACTIONS
• Allergic/Anaphylactic– Urticarial rash ------------> full anaphylaxis
• Delayed Reaction– Serum sickness at 10 - 14 days: fever, malaise,
H/A, lymphadenopathy, polyarthritis, urticaria– Often not associated with sting by patient
• Usual Reactions– Encephalitis, GBS, neuritis, vasculitis
HYMENOPTERA - Mx
• First Aid– Ice bag to site, remove stinger, epipen prn
• Local Wound care in ED– Ice, remove stinger, tourniquet, limb down, can
inject 0.1 ml of 1:1000 epi into site
• Further Mx will depend on severity– Local reaction, allergic reaction, anaphylactic
reaction
ED Management
• Local Reaction– Local wound care, benadryl po, ibuprofen po– Observe 1hr, d/c if well
• Urticarial Reaction– Local wound care, benadryl po, ibuprofen po– Observe 2-3 hrs, d/c if well– Educate, bracelet, Epipen Rx, allergist referral,
Rx with benadryl +/- steroid
ED Management
• Anaphylaxis– Epinephrine sc, im, iv– Benadryl iv– IV fluids– Ranitidine +/- Cimetidine– Ventolin +/- Racemic epi neb– Methylprednisone– Local wound care– Admit
MARINE ENVENOMATIONS
• 2000 species of venemous marine animals
• General Mx– Remove from water: drowning MCC of death– Local wound care– ? Specific antivenom– Be prepared to manage anaphylaxis
Three Mechanisms of EnvenomationO h , L ook a t th e cu te lit t le fish y!
O c top iS easn akes
B ites
Je llyfishM an -o-w arS ea w aspF ire co ra ls
N em atocys ts
B on y F ishS ea U rch in /s ta rfish
C on e S h e llsS tin g rays
S tin g s
M arin e E n ven om ationM ech an ism s
BITES
• Octopi– Local wound care: irrigate,
debride, dress, tetanus, analgesia
– Blue - ringed Octopus can be lethal (tetrodotoxin like venom)
BITES
• Seasnakes– 50 species, all toxic, 7 fatal
– Most bites do not result in envenomation b/c fangs short/loose ---> poor delivery of venom
– Local wound care + polyvalent sea snake antivenom
NEMATOCYSTS
• Nematocyst = spring - loaded venom gland that suddenly everts and delivers venom
• Often located on tentacles• Remain functional after animals death• May still be “loaded”when in skin• Local reaction, allergic reaction, toxic
reaction (N/V/D, CP, cramps, SOB, paralysis, cardiorespiratory collapse)
NEMATOCYSTS
• General Mx– Cut off tentacles– Inactivate nematocysts: VINEGAR– Remove nematocyts: credit card scrape– Antihistamine, analgesia– Antivenom only exists for seawasp
NEMATOCYSTS
• Jellyfish– Usually only local reaction
– Remove tentacle, vinegar, credit card scrape, antihistamine, analgesia
NEMATOCYSTS
NEMATOCYSTS
• Box Jellyfish (Seawasp)– Australia, Indian ocean– MOST deadly of all envenomating marine life– 25% fatality rate; more deaths than sharks!– One box can kill 10 humans– Cardioresp arrest within minutes– Mx: ABCs, remove tentacles, VINEGAR,
credit card scrape, ANTIVENOM (Chironex)
NEMATOCYSTS
NEMATOCYTS
• Portuguese Man -o - war– Southern US coast line– Not a true jellyfish– Usually only local reaction– Potential for full CV collapse– Many deaths reported– Mx: ABCs, remove tentacles, vinegar, credit
card scrape, NO antivenom exists
STINGS
• Stinger = specialized apparatus that punctures skin and delivers venom
• Mx– Remove stinger (? Xray to r/o stinger in tissue)– Irrigate copiously, tetanus, analgesia– HOT WATER for 30 - 90 min (inactivates the
heat labile venom; hot as possible)– Antivenom exists for stonefish stings
STINGS
• Starfish – Most nonvenomous
– Crown - of - thorns: severe local reaction
STINGS
• Sea Urchins– Toxic coated spines
– Severity depends on species
– Usually only local reaction
– Imbedded spines problematic
STINGS
• Stingray– Barbs on tail
– Stepped on in shallow water
– Tail spines ---> laceration
– Stinger: local +/- systemic rxn (N/V/D, cramps, CP, SOB)
– Remove stinger, irrigate, HOT water, tetanus, abx to cover vibrio
STINGS
• Bony fish (Lionfish, Stonefish)• Venomous spins on fins• Stepped on or handled• Will attack b/f swimming away• Severe local rxn: pain, swelling• Systemic rxn: N/V/D, syncope,
SOB, paralysis, CV collapse• ANTIVENOM exists
The Goods on Marine Envenomations
L ook b u t D O N 'T tou ch
L oca l w ou n d careA n tiven om fo r sn akes
B ITE Soc top i
seasn akes
R em ove ten tac lesV IN E G A R
C red it ca rd sc rap eA n tiven om fo r sea w asp s
N E M A TO C Y S TSje llyfish , sea w asp
m an - o f - w ar
R em ove s tin g erIrrig a te
H O T W A TE RA n tiven om fo r s ton e fish
S TIN G Ss ta rfish , u rch in s
s tin g ray, b on yfish
M an ag em en t