Adrenaline (epinephrine) is the emergency treatment for a severe reaction. Given promptly, adrenaline can treat the features of anaphylaxis by acting on adrenoceptors. As an alpha-receptor agonist, it reverses vasodilatation and reduces oedema. As a beta-receptor, it dilates the airways, increases the force of myocardial contraction, and suppresses further histamine and leukotriene release.
There are three alternative injection kits prescribed to patients, Emerade, EpiPen and Jext.
Emerade is a pre-filled syringe encased in an auto-injector. It delivers a single dose of adrenaline when pressed against the muscle of the outer thigh. Distributor: Bausch + Lomb UK Limited 106-114 London Road Kingston upon Thames KT2 6TN United Kingdom. Tel: +44 (0)208 781 0001 firstname.lastname@example.org
EpiPen has a spring-loaded concealed needle that delivers a single measured dose when the pen is jabbed against the muscle of the outer thigh. Distributor: Meda Pharmaceuticals Ltd, Skyway House, Parsonage Road, Takeley, Bishop’s Stortford CM22 6PU. Tel 0845 460 0000.
Jext is a single-use adrenaline auto-injector. it has a locking needle shield which engages after use, designed to protect against accidental needle stick injury. Distributor: ALK-AbellÃ³ Ltd, 1 Manor Park, Manor Farm Road, Reading, Berkshire RG2 0NA. Tel: 0118 903 7940.
Unwanted effects are rare when appropriate doses of adrenaline are given by intramuscular injection. However, the doctor should consider all co-existing medical conditions and check for potential interactions. For example, beta blockers and ACE inhibitors may hinder treatment.
The Junior versions of Jext and Emerade devices are recommended for children weighing 15-30kg, although doctors may use their judgement and prescribe it for children weighing under 15kg. The higher dose versions of Jext and Emerade are suitable for adults and for children over 30kg. However, some doctors prescribe the higher dose device for children weighing between 20-30kg if the individual case warrants it (e.g. if the child is prone to reactions that are particularly severe).
Emerade also has a 500 micrograms dose.
Junior versions of EpiPen deliver a 150mcg dose for infants and children who weigh between 7.5kg and 25kg. The higher dose EpiPen delivers a 300mcg dose in adults and children weighing over 25kg.
Adrenaline injectors have expiry dates and may be less effective after that date. Therefore it is helpful to do a regular audit of prescribed adrenaline to identify those patients whose last prescription was more than two years ago. See this link for an example of an audit of injectable adrenaline.
If the patient is switched from one device to another, this could cause confusion and so careful retraining will be necessary.
Asthma inhaler devices: Patients should also be instructed how to use their Salbutamol (Ventolin) or Terbutaline (Brycanyl) inhaler as asthma can be a feature of the reaction. Their inhaler technique should be checked regularly to ensure they are competent at using the device. Otherwise, a spacer or alternative suitable device should be prescribed. Guidelines for asthma management can be seen here. Also refer to Lavorini et al, 2010.
An allergy management plan
There is evidence that the risks are reduced if the patient receives expert advice and assessment in a specialist allergy clinic and participates in an agreed management plan (Ewan and Clark, 2005). Where this happens, fewer patients have further reactions and when these do occur, they are mostly mild. Importantly, the patient should be educated on measures to avoid the allergen in the future. Furthermore, dietician involvement in food anaphylaxis is imperative in formulating the action plan.
Families and carers, including school staff, must be competent to recognise when an allergic reaction has started and how to administer adrenaline. Follow-up is important to ensure regular re-training and assessment of allergy status.
As stated above, the presence of asthma in a patient with allergy must be considered a significant risk factor. Therefore regular assessment of the patient’s asthma control is vital, with appropriate action to ensure control is achieved and maintained. This would include adjustment of medication dose, or addition of medication, or a change in inhaler device. An asthma action plan should be agreed between the patient and their doctor. There is evidence that these improve asthma control, reduce exacerbations and hospital admissions. Visit this website for more information.
Prescribing medicines for patients with allergies
When prescribing medicines for people with food allergies, doctors are advised to check the ingredients and excipients to ensure the food allergens they react to are not present.
Example of implementation of care for people with anaphylaxis:
The RCPCH Allergy care-pathway for anaphylaxis provides a resource for local implementation of care by a multidisciplinary team. This is focused on creating networks between staff in primary and community health care, social care, education and hospital-based practice to improve services for children with allergic conditions. Visit the RCPCH’s website.
This is supported by the Itchy Sneezy Wheezy website for the implementation programme of the pathway which includes action plans, video clips for training of patients and professionals, and a multi-media training guide for professionals.