Anaphylactic reaction

Anaphylaxis can be defined as a severe systemic hypersensitivity reaction (National Institute for Health and Care Excellence, NICE, 2020; Resuscitation Council UK, 2021). The most common causes of anaphylaxis reported in the UK are due to food including nuts and cow’s milk (Conrado et al, 2021), drugs such as antibiotics and chemotherapy, and insect bites (Resuscitation Council UK, 2021; Turner et al, 2020). The onset of anaphylaxis is usually rapid on exposure to an allergen (trigger) affecting airway and/or breathing and/or circulation with or without skin and mucosal changes and leading to a life-threatening situation (NICE, 2020; Resuscitation Council UK, 2021).

See anaphylaxis for more information on the condition. 

Severe anaphylaxis and mortality are associated with following factors:

1. Drugs: antibiotics (penicillin and cephalosporins), radiocontrast dyes and other diagnostic agents, antineoplastics, general anaesthesia and neuromuscular blocking agents
2. Age: elderly people
3. Comorbidities: cardiovascular or respiratory diseases, for e.g. hypertension & asthma
4. Polypharmacy / multiple medications: use of antidepressants, angiotensin-converting enzyme inhibitors and β-blockers
5. Systemic mastocytosis: It is a clonal disorder which involves increased release of mast cell mediators resulting in frequent and severe hypersensitivity reactions
6. Vigorous exercise
7. Psychological burden (Regateiro et al, 2020)

Anaphylaxis is potentially fatal and early recognition of serious illness is vital for recovery. If anaphylaxis is suspected, an early call for emergency help is imperative. The assessment of anaphylaxis in adults and children should follow best practice guidance consisting of effective communication and collaboration between healthcare professionals and patients (NICE, 2020).

A continuous review of the diagnosis and management of anaphylaxis is recommended (NICE, 2020). An ABCDE approach (Table 1) to the initial assessment and management of anaphylaxis is advised. Assess for rapid progression of airway and/or breathing and/or circulation problems. In most anaphylaxis cases, there will be skin and/or mucosal changes, e.g., urticaria, angioedema, but these changes alone are not a sign of anaphylaxis and can be absent in up to 20% of cases (Resuscitation Council UK, 2021).

It is important that the principles of life support are followed in the management of anaphylaxis (Resuscitation Council UK, 2021).

Guidance available for the treatment of anaphylaxis in adults and children recommends a complimentary approach in any context, with some small variances in treatment which will be emphasised.

• Access help from the resuscitation team or ambulance service as soon as serious illness is recognised (airway and/or breathing and/or circulation issues) and enable access to the area.
• Where reasonably practicable, keep a record of the time of onset and events directly before symptoms began (NICE, 2020) and safely remove the allergen where possible (Resuscitation Council UK, 2021).
• Ensure that the patient does not sit up, stand, or walk suddenly as this can cause an imminent drop in blood pressure. Patients should be laid flat with their legs raised, unless there are airway and breathing problems, in which case upright positioning of the head and torso at an angle of 45 degrees should be adopted (Resuscitation Council UK, 2021). The left lateral

1. Biphasic reaction- Approximately 20% people have relapse of symptoms or develop new symptoms within 1 to 72 hours of initial allergy-related presentation without further exposure to the allergen (Pourmand et al, 2018)
2. Respiratory complications: airway obstruction and respiratory arrest (Rojas-Perez-Ezquerra et al, 2017)
3. Cardiovascular complications: Arrhythmias (atrial fibrillations), angina/ischemia, hypotension, syncope, and cardiac arrest (Rojas-Perez-Ezquerra et al, 2017)
4. Central nervous system symptoms: headache, restlessness, seizures, and altered level of consciousness (Alqahtani et al, 2020)
5. Gastro-intestinal complications: abdominal pain, cramps, nausea, vomiting, and diarrhea (Alqahtani et al, 2020)
6. Death (Alqahtani et al, 2020)

1. Take blood samples for mast cell tryptase testing. First sample should be collected immediately after emergency treatment and second sample should be taken within 1–2 hours (but no later than 4 hours) from the onset of symptoms. Inform the patient that test may be repeated during follow-up appointment (NICE, 2020). Increase in serum tryptase levels starts within minutes of anaphylaxis and reverts gradually to normal levels over the next 6–24 hours (National Clinical Guideline Centre (UK), 2014). However, a result showing normal mast cell tryptase level does not mean that you could exclude anaphylaxis (Resuscitation Council UK 2021). 
   In children below the age of 16 years, this test should be conducted only if the cause of anaphylactic reaction is not known or is thought to be related to venom or drug (NICE, 2020).
2. Document the timing of the occurrence of reaction, clinical presentations, and the circumstances immediately before the onset of

References

Alqahtani AN, Alanazy S H,  Aljameel OSH et al. Evaluation of Diagnosis and Management of Anaphylactic shock in Emergency Room: A Literature Review. International Journal of Pharmaceutical Research & Allied Sciences, 2020, 9(1):93-98

Conrado BA, Lerodiakonou D, Gowland MH et al. Food anaphylaxis in the United Kingdom: analysis of national data, 1998-2018. BMJ. 2021;17;372:n251. https://doi.org/10.1136/bmj.n251.

Greater Manchester Critical Care Skills Institute. Acute illness management. 2022. https://www.gmccmt.org.uk/critical-care-skills-institute/acute-illness-management/ (accessed 21 November 2022)

Lee SY, Lee SC, Shin SD et al. Epidemiology and outcomes of anaphylaxis-associated out-of hospital cardiac arrest. PLoS ONE 2018;13(3): e0194921. https://doi.org/10.1371/journal.pone.0194921

Lott C, Truhlář A, Alfonzo A et al. Special Circumstances Writing Group Collaborators. European Resuscitation Council Guidelines 2021: Cardiac arrest in special circumstances. Resuscitation. 2021;161:152–219.

National Institute for Health and Care Excellence. Anaphylaxis Assessment to confirm an anaphylactic episode and the decision to refer after emergency treatment for a suspected anaphylactic episode. NICE clinical guideline 134. 2020.