Anaphylaxis resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Vidit Bhargava, M.B.B.S [2]

Definition

An acute, severe, potentially life threatening type 1 hypersensitivity reaction, following repeated exposure to an allergen to which an individual is already sensitised.

Causes

Life Threatening Causes

Any of the factors precipitating anaphylaxis can be life threatening.

• Food: Peanuts, Tree nuts, walnuts, pecans, milk, soyabean, wheat, eggs, pistachios, filberts, cashews, almonds, etc.
• Shellfish: crab, crayfish, prawns, shrimp, lobster, etc.
• Medications: Penicillin, Sulfa antibiotics, Allopurinol, and many other drugs
• Diagnostic materials: IV contrast material and dyes
• Insect venom: including bees, wasps, ants
• Natural rubber latex
• Idiopathic/ Coital anaphylaxis

Diagnostic Criteria

It is diagnosed with one of the following criteria:
♦ Acute onset of a reaction (mins to hours) involving skin, mucous membrane or both. Additionally including atleast one of the following:

• Respiratory compromise or
• Cardiovascular compromise/Evidence of end organ dysfunction.

♦ 2 or more of the following in a patient known to come in contact with an established allergen:

• Skin/mucosal tissue involvement
• Respiratory compromise
• Reduced blood pressure
• Gastrointestinal manifestations

♦ Reduced blood pressure after exposure to a known allergen.

Management

Shown below is an algorithm summarizing the approach to [[Anaphylaxis]].

Characterize the symptoms & signs: Skin, subcutaneous tissue and mucosa: ❑ Flushing, itching, urticaria, angioedema, rash, piloerection ❑ Periorbital itching, erythema and edema; conjunctival erythema, tearing Respiratory: ❑ Nasal itching, congestion, rhinorrhea, sneezing ❑ Throat itching and tightness, dysphonia, hoarseness, stridor, dry staccato cough ❑ Tachypnea, dyspnea,chest tightness, wheezing/bronchospasm ❑ Cyanosis ❑ Respiratory arrest Gastrointenstinal: ❑ Pain, nausea, vomiting, diarrhea Cardiovascular: ❑ Chest pain, tachycardia, palpitations ❑ Hypotension, feeling faint ❑ shock ❑ Cardiac arrest Central nervous system: ❑ Anxiety, irritability ❑ Throbbing headache ❑ Altered vision and mental status

Consider alternative diagnosis: ❑ Acute asthma ❑ Anxiety/Panic attack ❑ Syncope

Remove patient from exposure/trigger

Do all 3 simultaneously ❑ Call for help ❑ Inject aqueous epinephrine (adrenaline) IM in the mid-anterolateral aspect of the thigh, 0.01 mg/kg of a 1:1,000 (1 mg/mL) solution Maximum dose 0.5 mg (adult) or 0.3 mg (child) Record the time of the dose and repeat it in 5-10 minutes, if needed or ❑ Intravenous epinephrine: In patients with hypotension/cardiorespiratory arrest and those not responding 1:100,000 solution of epinephrine (0.1 mg [1 ml of 1:1000] in 100 ml saline) intravenously by infusion pump at an initial rate of 30-100 ml/hr (5-15 mg/min) Titrate based on clinical response or epinephrine side effects ❑ Place patient on back/comfortable position; elevate legs

Yes

Patient has one of the following? ❑ Respiratory distress ❑ Recieved repeated doses of epinephrine ❑ Asthma/other respiratory disease ❑ Co-existing cardiovascular disease

❑ Give high flow supplemental oxygen (6-8 L/min)

No

Patient hypotensive despite epinephrine?

Yes

No

❑ Establish IV access ❑ Give 1-2 litres of 0.9% saline rapidly, 5-10 ml/Kg in first 5-10 mins ❑ Give vasopressors (dopamine) 400mg in 500ml of 5% dextrose at 2-20 mg/kg/min to maintain a target systolic BP > 90 mm Hg

Secondary therapy after epinephrine (evidence not clear) H1 antihistaminics: ❑ Diphenhydramine IM or slow intravenous infusion - 25 to 50 mg in adults, and 1 mg/kg up to 50 mg in children H2 antihistaminics: ❑ Ranitidine - 1 mg/kg in adults, and 12.5 to 50 mg in children IV or IM

❑ Observe the patient for biphasic anaphylaxis Total period of observation depends on a) clinical condition b) patients access to emergency care setting from home ❑ Provide auto-injectable epinephrine and action plan for future events at discharge

References

Template:WikiDoc Sources