From itch to cardiac arrest – a guide to anaphylaxis
Case:
69yr old female presented to ER with h/o 1 episode of vomiting and generalized weakness for 1 hour. Bystanders also gave h/o itching all over the body after vomiting. While the patient was being shifted to bed from wheelchair to bed she developed up-rolling of eyes and stiffening of her limbs. She was connected to monitors and connected to oxygen. Patient was drowsy, HR:60/min, BP:NR, SpO2: NR. Provisional diagnosis of anaphylactic shock she was treated with INJ.ADRENALINE 0.5mg IM on the anterolateral right thigh. She regained consciousness, HR:90/min, BP:110/50mmHg, SpO2: 100%RA.
Allergic reactions are unpredictable and scary for both patient and doctor. At one moment patient says feel itchy and the next their throat starts to close. A Swift informed action can make a difference in the outcome.
Definition
World Allergy organization has defined anaphylaxis as “a serious systemic hypersensitivity reaction that is usually rapid in onset and may cause death. Severe anaphylaxis is characterized by potentially life-threatening compromise in airway, breathing and/or the circulation, and may occur without typical skin features or circulatory shock being present.”
Criteria for diagnosing anaphylaxis:
Pathogenesis of Anaphylaxis:
Management of Anaphylaxis
Resuscitation Council UK. Emergency treatment of anaphylaxis Guidelines for healthcare providers Working Group of Resuscitation Council UK [Internet]. Resuscitation Council UK; 2021. Available from: https://www.resus.org.uk/sites/default/files/2021-05/Emergency%20Treatment%20of%20Anaphylaxis%20May%202021_0.pdf
Refractory anaphylaxis
Anaphylaxis not responding to 2 doses of IM adrenaline
Other interventions
- Oxygen
- IV fluids
- H1 and H2 antagonists
- Glucocorticoids – no evidence in preventing biphasic reactions
- Inhaled beta 2 agonists – persistent bronchospasm even after IM adrenaline
- Inhaled Adrenaline- laryngeal edema
- GLUCAGON – patients on beta blockers, refractory anaphylaxis (1-5mg slow iv bolus over 5 min f/b 5-15mcg/min infusion)
- Pediatrics: 20-30mcg/kg
- Methylene blue: intravenous infusion of methylene blue 1.5 mg/kg in 50 ml 5% Dextrose (case series on refractory anaphylaxis treated with Methylene blue infusion are available. Methylene blue is a competitive inhibitor of NO synthase and guanylate cyclase. Hence prevents vasoplegia)
- V-A ECMO – there are case series on refractory anaphylaxis being treated with V-A ECMO
Criteria for admission:
- Hypotensive during ED course
- Progression or persistence of symptoms
- History of severe asthma
- Current asthma exacerbation
- History of biphasic or severe reactions
- Requires fluids
- Lower airway symptoms
- Requires > 1 Epinephrine dose
- Upper airway obstruction
- Refractory to Epinephrine
Biphasic reaction
A biphasic reaction is defined as a recurrent reaction or appearance of new symptoms after the initial allergy-related presentation without further exposure to the causative agent. Prevalence of biphasic reaction is 1-20%. Mean time to onset >8 h
Role of serum Tryptase
During acute anaphylaxis, serum tryptase levels are increased from 15 min to 3 h or even longer, after the onset of symptoms
A level of serum tryptase half to two hours after the start of the reaction (1.2 × baseline tryptase) +2 μg/L supports a diagnosis of anaphylaxis
Serum tryptase is not always elevated in anaphylaxis, especially in children and with food triggers in all ages
It is recommended to take sample for s. tryptase within 2 hours of onset of symptoms and after 24hrs (for baseline value, but the evidence is weak.
