Anaphylaxis in the Radiology Department

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Anaphylaxis in the Radiology Department

• Anita Pozgay, MD, FRCPC Emergency Medicine,
• Dip. Sport Med Tropical Med.

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Case One

• A 7 year old comes in to the ED after an possible
  exposure to peanut butter
• He has a severe nut allergy for which he was
  prescribed an EpiPen
• He was recently admitted to PICU for a severe
  asthma attack but was not intubated
• Mom gave him some oral Benadryl and he is no
  longer itchy but still has lip swelling

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Case One continued

• He is sent for a CXR due to decreased air entry
  in the lower lobes
• While in radiology, he becomes acutely SOB and
  his lip becomes more swollen
• What do you do now?

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Case Two

• A 45 y o woman involved in a MVC needs a CT abdo
  after she is stabilized in the ED
• She received 2 L NS for a hypotensive episode and
  her BP is now 120/70
• She has a positive FAST U/S
• Although her CXR is normal she has palpable lower
  rib fractures a distended abdomen

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Case Two continued

• She is given both oral and IV contrast for her CT
• She becomes hypotensive again!
• What do you do now?
• There is no rash

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Case Three

• A 67 y o man is stung by an insect while
  gardening
• He developed pruritus, dizziness, and SOB 20 min
  later so he called 911
• He self-treated with Benadryl po and was given
  another 50 mg IV by EMS due to persistent sx and
  rash
• He is now asymptomatic and refusing transport to
  hospital

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Case Three Do you transport?

• EMS convinced him to get checked out in the
  hospital
• On arrival, he becomes hypotensive, and his hives
  reappeared, along with facial edema
• An ECG shows T wave inversion in his lateral
  leads
• PHx MI, HTN, IV contrast allergy
• Meds ASA, metoprolol, lisinopril

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Case of EIA

• 28 year old male, after eating spaghetti and then
  playing soccer 1 hr later, developed urticaria
  dizziness
• attempted to drive to hospital but pulled over
  because worse
• EMS vitals BP 80/42, HR 90, RR 24
• Rx w/ epi and 1 litre NS
• In ED BP 130/85, chest was clear and hives
  gone but skin still edematous

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Exercise Induced Anaphylaxis

• Clinical features indistinguishable from allergen
  induced anaphylaxis
• food dependent food independent forms (also
  cholinergic urticaria)
• mechanism not fully known, but thought exercise
  lowers threshold for mast cell degranulation esp
  after a food allergen triggers an IgE response

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Exercise-Induced Allergic Syndromes
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Natural History of EIA

• N 365 respondents with 10 yr hx of EIA to 75
  item questionaire
• EIA if anaphylactic Sx with exercise but not with
  passive warming
• Shadick, Nancy A., et al. The Natural History of
  Exercise-Induced Anaphylaxis Survey results
  from a 10-year follow-up study, J Allergy Clin
  Immunol 1999 104 123-7.

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Results of Survey

• frequency of attacks lesson over time
• a wide range of activities associated but more CV
  demand more likely
• 70 had atopy or family hx of it
• subjects avoided attacks by not exercising in
  humid weather or high allergy seasons
• no single trigger identified most common food
• H1 blockers/ epi were used by 30 emergently
  Role of prophylaxis?

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Management Questions?

• What is the first line of therapy?
• When do you give epi? Type? Route?
• Do all patients need Epinephrine?
  Corticosteroids?
• What is the role of combined H1 H2 blockers?
• Who needs to be monitored? Referred?
• Who needs an EpiPen?

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Epidemiology

• Likely under reported due to lack of recognition
  or self treatment in the field
• in Ontario 4 cases/ 1 million
• in Germany 10 cases/100 000
• in Minnesota, U.S.A. 17/19,122 visits
• in Brisbane, Australia 1/440 visits

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Common Causative Agents

• Drugs Antibiotics, ASA, NSAIDS, sulfa, opioids,
  IV contrast dye
• Foods Peanuts, Seafood, Eggs, milk
• Latex gloves
• Insect Stings
• Physical Factors Exercise (FDEIA), Cold/Heat

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Definitions

• Anaphylaxis against protection, a severe
  systemic allergic reaction in a previously
  sensitized person must include respiratory
  difficulty or vascular collapse
• hives/angioedema NOT universally present!
• Allergic reactions localized urticaria,
  angioedema, contact dermatitis,
  rhinoconjunctivitis

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Pathophysiology

• Sensitization occurs when IgE adheres to the mast
  cell Ag (allergen)
• IgE specific
• Degranulation of mast cell
• mediators

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Anaphylactic vs. Anaphylactoid

• Anaphylactoid has the same clinical features as
  anaphylaxis but is not IgE mediated
• Instead it is due to direct mast cell
  degranulation and thus, does not require prior
  sensitization

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Clinical Features

• SMOOTH MUSCLE CONTRACTION
• abdominal cramps
• nausea
• rhinitis
• conjunctivitis

• CAPILLARY LEAK
• urticaria
• angioedema
• laryngeal edema
• hypotension/syncope

• MUCOSAL SECRETIONS
• bronchospasm
• diarrhoea
• vomiting

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Urticaria versus Angioedema

• Both characterized by transient, pruritic, red
  wheals on raised serpiginous borders
• urticaria due to edema of dermis
• angioedema due to edema of subcutaneous tissues

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DDx Anaphylaxis

• MI/arrhythmia/cardiogenic shock
• Airway obstruction due to other causes FB
  aspiration, asthma, COPD, epiglottitis,
  peri-tonsillar abscess, etc.
• Flushing syndromes (eg carcinoid)
• Vasovagal syncope
• Panic attack
• Scombroid poisoning
• Hereditary angioedema

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Management Questions?

• What is the first line of therapy?
• When do you give IV vs IM epi?
• Do all patients need Epinephrine
  corticosteroids?
• What is the role of combined H1 H2 blockers?
• Who needs to be monitored? Referred?
• Who needs an EpiPen?

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Key Management of Anaphylaxis

• 1st line of therapy
• AWARENESS
• RECOGNITION
• TREAT QUICKLY
• CALL FOR BACK-UP!

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Management Adult Epi dosing

• Epinephrine
• 0.3 mg (0.3 ml) 11000 solution IM
• (NOT SC or IV)
• may repeat in 5 min X 1
• (empirical only but safe)

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Epi Pediatric Dosing(0.01 ml/kg)

• Age (yrs) Volume of Dose (mg)
• 11000(1mg/ml)
• 1 0.1 ml 0.1
• 2-3 0.2 ml 0.2
• gt 4 0.3 ml 0.3

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EPI cautions Co-morbidities

• Thyroid disease
• Cocaine addicts
• CAD on BBlockers, ACEi
• Depression using MAOIs or TCAs

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Mechanisms of Epinephrine

• Alpha agonist effects increase peripheral
  resistance, BP, reduce vascular leakage
• Beta agonist effects cause bronchodilation,
  positive cardiac inotropy/chronotropy (caution in
  CAD pts!)

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Dangers of Epinephrine IV

• Only use IV Epi if patient has refractory shock
  not responding to fluid bolus first
• dose 0.1 mg (10 ml) 1100,000 dilution over 10
  minutes
• must be on cardiac monitor
• caution in elderly or those with CAD
• may cause supraventricular/ventricular
  dysrhythmias!

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ManagementDo all patients need Epi?

• Epinephrine reverses mediator release while
  antihistamines (H1) do not
• Epinephrine should be used for all systemic signs
  of allergy airway edema (includes tongue/lips),
  SOB, cyanosis, hypotension

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Grading of Anaphylaxis
Grade Skin GI tract Resp CV Neuro
1 Local pruritus, hives, mild lip swelling Oral tingling, pruritus
2 Generalized pruritus, hives, flushing, angioedema Above plus nausea /- emesis Nasal congestion/ sneezing Activity change
3 Any of above Any of above repetitive vomiting Rhinorrhea, sensation of throat tightness Tachy ( gt 15 bpm) Above plus anxiety
4 Any of above Any of above diarrhea Hoarseness dysphagia, SOB, cyanosis Above arrhythmia /- dec BP dizziness Feeling of impending doom
5 Any of above Any above stool incont. Any above resp arrest Brady /- card arrest LOC
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Management Do all patients need Corticosteroids?

• Corticosteroids take 4-6 hours to work
• theoretically blunt the multi-phasic reaction of
  anaphylaxis
• the quicker the onset of anaphylaxis the worse
  the reaction/quicker resolution less likely to
  relapse
• Caution in IV steroids esp if given in bolus
  doses case reports of anaphylaxis!
• Oral form preferred if possible

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Histamine Classes

• H1 receptor stimulates bronchial, intestinal,
  smooth muscle contraction, vascular permeability,
  coronary artery spasm
• H2 receptor increase rate force of
  ventricular atrial contraction, gastric acid
  secretion, airway secretions, vascular
  permeability, bronchodilation, inhibition of
  histamine release

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Management What is the role of combined H1 H2
Antagonists?

• RCT, N91 w/ allergic syndromes
• 50 mg Benadryl (H1) saline vs. 50 mg Benadryl
  50 mg Ranitidine (H2) IV
• Endpoints of resolution of urticaria, angioedema,
  or erythema
• also measured subjective improvement vitals
• Lin et al., Improved outcomes in patients with
  acute allergic syndromes who are treated with
  combined H1 H2 antagonists, Annals of Emergency
  Medicine 36(5) 2000.

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Histamines Results

• Statistically significant diminution of
  angioedema and/or urticaria with addition of H2
  blocker
• study too small to determine if H2 blockers
  helpful in anaphylaxis (those with respiratory
  compromise /or hypotension)
• also significant decrease in HR in Rx group

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Back to Cases Management Case 1
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Case One Peanut allergy in asthmatic

• A 7 year old comes in to the ED after an possible
  exposure to peanut butter
• He has a severe nut allergy for which he was
  prescribed an EpiPen
• He was recently admitted to PICU for a severe
  asthma attack but was not intubated
• Mom gave him some oral Benadryl and he is no
  longer itchy but still has lip swelling

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Case One continued

• He is sent for a CXR due to decreased air entry
  in the lower lobes
• While in radiology, he becomes acutely SOB and
  his lip becomes more swollen
• What do you do now?

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Case 1 Conclusion

• He needs IM Epi!
• (He weighs 30 kg and thus 0.3 mg IM is fine.)
• O2, IV fluids, cardiac monitoring
• Consider Ventolin neb (esp if concurrent asthma)

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Case Two MVC Management

• A 45 y o woman involved in a MVC needs a CT abdo
  after she is stabilized in the ED
• She received 2 L NS for a hypotensive episode and
  her BP is now 120/70, HR 100
• She has a positive FAST U/S
• Although her CXR is normal she has palpable lower
  rib fractures a distended abdomen

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Case Two continued

• She is given both oral and IV contrast for her CT
• She becomes hypotensive again!
• What do you do now?
• There is no rash

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Case 2 Conclusion

• Is she in hypovolemic shock or anaphylactic?
  doesnt matter b/c both require IV crystalloids!
• There may be no rash initially
• Look for airway compromise/swelling intubate?
• IV contrast reactions are anaphylactoid and so
  prior sensitization not necessary (thus may be no
  prior hx of anaphylaxis)
• If no response to fluids give IV epi 1st via
  slow infusion, except if pulseless then may give
  IV bolus

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Case 3 Gardener Management
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Case Three

• A 67 y o man is stung by an insect while
  gardening
• He developed pruritus, dizziness, and SOB 20 min
  later so he called 911
• He self-treated with Benadryl po and was given
  another 50 mg IV by EMS due to persistent sx and
  rash
• He is now asymptomatic and refusing transport to
  hospital

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Case Three Do you transport?

• EMS convinced him to get checked out in the
  hospital
• On arrival, he becomes hypotensive, and his hives
  reappeared, along with facial edema
• An ECG shows T wave inversion in his lateral
  leads
• PHx MI, HTN, IV contrast allergy
• Meds ASA, metoprolol, lisinopril

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Case 3 Management Refractory Anaphylaxis

• Biphasic (multi?) reactions can occur typically
  after 3-4 hours but as late as 72 hours later!
• Beware of the patient with increased age and
  co-morbidities (eg. CAD) b/c anaphylaxis can
  cause cardiac ischemia
• B-Blockers ACEi blunt the catecholamine
  response

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Management Refractory Anaphylaxis Glucagon

• Glucagon increases inotropy/chronotropy
  causes smooth muscle relaxation independent of B
  receptors
• Dose 1-5 mg in adults (0.5 - 1 mg in kids)
  IV/IM

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Management Disposition Follow-up

• Inquire about possible antigen exposure
• Those with systemic reactions require a
  prescription for and instruction on how to use a
  EpiPen
• A Medic Alert Bracelet is useful
• Follow-up with an allergist for skin testing
  should be arranged particularly if the allergen
  is unknown

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EpiPen
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Summary

• Acute anaphylaxis is often poorly recognized
  treated due to the protean clinical features and
  variation in the speed of onset
• a trigger is often not found
• Pruritis is a universal feature and should
  differentiate anaphylaxis from asthma
• Expedious treatment w/ epi is necessary thus
  patient education on its use is essential

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