Allergic conditions Flashcards
T or F - antihistamines reduce rihnorrhoea and sneezing but are usually less effective for nasal congestion
True
True or false - antihistamines may be given in anaphylaxis following initial stabilisation of the pt, especially in pt with persistent cutaneous symptoms
True
Name 3 antihistamines that have a role in n+v
- promethazine teoclate
- cinnarizine
- cyclising
This antihistamine is included as an antiemetic in a preparation that can be bought OTC for migraine
Buclizine
True or false - all older antihistamines cause sedation
True
Which ones are more sedating and which ones are less sedating: Alimemazine tartrate, promethazine, chlorphenamine and cyclizine
Alimemazine tartrate and promethazine = more
Chlorphenamine and cyclizine = less
Sedating activity of some antihistamines is sometimes used to manage …. associated with some allergies
pruritis
Why do non sedating antihistamines cause less sedation and psychomotor impairment than the older antihistamines?
they only penetrate the BBB to a slight extent
Why is the use of 1st gen antihistamines in elderly pt potentially inappropriate (STOPP)?
safer, less toxic antihistamines are widely available
Immunotherapy using allergen vaccines containing house dust mite, animal dander (cat or dog) or grass pollen extract and tree pollen extract can reduce …
symptoms of asthma and allergic rhinoconjunctivitis
vaccines containing wasp venom or bee venom extract may be used to
reduce risk of severe anaphylaxis and systemic reactions in pt with hypersensitivity to wasp and bee stings
an oral preparation grass pollen extract is licensed for
disease-modifying treatment of grass-pollen induced rhinitis and conjunctivitis
an oral prep of house dust mite extract is licensed for
disease-modifying treatment of house dust mite allergic rhinitis or asthma in certain pt
Desensitisation treatment with peanut protein may be offered to
pt with peanut allergy in childhood, and treatment can be continued into adulthood
what is Omalizumab
mab that binds to immunoglobulin E (IgE)
discuss use of omalizumab
- mab binds to IgE
- Used as additional therapy in pt with proven IgE-mediated sensitivity to inhaled allergens, whose severe persistent allergic asthma cannot be controlled adequately with high dose ICS together with LABA
- must be initiated by physicians in specialist centres experiences in treatment of severe persistent asthma
- Also indicted as add on therapy for treatment on chronic spontaneous urticaria in pt who have had an inadequate response to H1 antihistamine treatment
what is anaphylaxis
Severe, life threatening, generalised or systemic hypersensitivity reaction
prompt treatment required
anaphylaxis is characterised by
Characterised by rapidly developing airway and/or breathing and/or circulation problems
Usually associated with skin and mucosal changes
most common allergens that cause anaphylaxis include
Food (e.g. Peanuts, sesame, tree nuts, soy, shellfish, cows milk)
Drugs (e.g. abx, aspirin and other NSAIDs, neuromuscular blocking drugs, chlorhexidine, contrast media, vaccines)
Venom (e.g. insect stings)
Latex
anaphylaxis is more common after what route of administration?
Parenteral administration
Resuscitation facilities must always be available for injections associated with special risk
True or False - Anaphylactic reactions may also be associated with additives and excipients in foods and medicines
True
True or false - refined arches (peanut) oil which is present in some medicinal products is likely to cause an allergic reaction in patients
False
Unlikely
However still wise so check full formula of preparations which may contain allergens
True or false - some patients are at higher risk of anaphylaxis e.g. asthma, or increased likelihood of repeated exposure to same allergen such as those with venom or food allergies
true
ABCDE
airways
breathing
circulation
disability
exposure
true or false - cardiopulmonary arrest may follow an anaphylactic reaction
true
start CPR immediately
full treatment pathway for suspected anaphylaxis
- ABCDE, diagnosis - look for sudden onset of airway/and or breathing and/or circulation problems, and usually skin changes e.g. itchy rash
- call for help (999)
- remove trigger if possible (e.g. stop infusion, remove stinger)
- lay pt flat, with or w/o legs raised, to aid in restoration of BP; or siting may make it easier to breathe; or recovery position if unconscious, or left side if pregnant to prevent artovaval compression
- give IM adrenaline 1st line
- repeat dose after 5 mins if no improvement in condition
- if no improvement in respiratory and/or CV problems despite 2 appropriate doses of IM adrenaline, escalate care quickly and manage as having refract anaphylaxis
is nebulised adrenaline effective ad adjunct to treat upper airways obstruction caused by laryngeal oedema?
Yes
but only after treatment with IM adrenaline, not as alternative
Other treatments used in anaphylaxis (Adjunct)
High flow oxygen should be given as soon as it is available
Give IV fluids to patients with hypotension or shock, or if poor response to initial dose of adrenaline
are antihistamines recommended as part of initial emergency treatment of anaphylaxis?
no
following stabilisation of patient, you can give antihistamine … true or false
true
give a non sedating oral antihistamine e.g. cetirizine
especially in pt with persistent cutaneous symptoms e.g. urticaria and/or angioedema
if oral administration not possible, IM or IV chlorphenamine can be given
discuss use of CCs as anaphylaxis treatment
Routine use of CCS for emergency treatment of anaphylaxis not recommended
Consider CCS after initial resuscitation for refractory reactions or ongoing asthma or shock
CCS must not be given preferentially to adrenaline
CCS should be given via oral route where possible
use of bronchodilators in anaphylaxis
Inhaled bronchodilator therapy with salbutamol and/or ipratropium bromide may also be considered for patients with persisting respiratory problems, but should not be used as an alternative to further treatment with adrenaline
what is refractory anaphylaxis
Anaphylaxis that requires ongoing treatment due to persisting respiratory and/or CV problems despite 2 appropriate doses of IM adrenaline - seek early critical care support
patients with refractory anaphylaxis need to be treated with …. & what to give if this isn’t possible
IV adrenaline infusion
IV adrenaline should only be given by experienced specialists and in a setting where patients can be carefully monitored
If it cannot be administered safely e.g. due to patient being outside hospital setting, continue to give IM adrenaline at 5 minute intervals while life threatening CV and/or respiratory features persist
Adrenaline therapy should be supported with IV fluid therapy
discharge and follow up after pt has had anaphylaxis
Prior to discharge from hospital, patients or their family and carers should be provided with 2 adrenaline auto injectors, trained on their correct use, and be advised to carry it would them at all times
Pt provided with auto injectors should have appropriate follow-up including contact with their GP
Patients and their family or carers should also be provided with info about anaphylaxis, the risk of biphasic reaction (with clear instructions to return to hospital if symptoms return), avoidance of suspected triggers, and what to do if anaphylactic reaction occurs
An Emergency Management or action plan should be provided, and referral to a specialist allergy clinic made
a rare but potentially serious reaction that occurs when anaphylaxis symptoms recur within 72 hours of the initial reaction, without re-exposure to the trigger
Which patients should recieve auto injectors after having had anaphylaxis?
Provision of adrenaline auto injectors are appropriate for all patients who have had anaphylaxis, with the exception of those with a drug induced reaction unless future exposure to the trigger drug will be difficult to avoid
patient has had anaphylaxis to a drug. will they need an epipen to carry with them going forward?
no they dont need it unless future exposure to the trigger drug will be difficult to avoid
What is allergic angioedema & when should it be managed as anaphylaxis
Angioedema can be caused by allergic reaction
Involves swelling of deeper tissues, most commonly in eyelids and lips, and sometimes the tongue and throat
Allergic angioedema that occurs with life-threatening airway and/or breathing and/or circulatory problems should be managed as anaphylaxis
treatment of hereditary angioedema needs to be
under specialist supervision
treatment of hereditary angioedema - the following are ineffective
Unlike allergic angioedema, adrenaline/epinephrine, CCs and antihistamines should NOT be used for treatment of acute attacks (including attacks involving laryngeal oedema) as they are ineffective and may delay appropriate treatment - intubation may be necessary
hereditary angioedema - treatment
Administration of C1-esterase inhibitor, an endogenous complement blocker derives from human plasma, (in fresh frozen plasma or in partially purified form) can terminate acute attacks of hereditary angioedema
Can also be used for short term prophylaxis before dental, medical or surgical procedures
Conestat alfa and icatibant are licensed for treatment of acute attacks or hereditary angioedema
Short term prophylaxis with tranexamic acid or danazol is started several days before planned procedures (e.g. dental work) and continued for 2-5 days afterwards
Danazol should be avoided in children because of its androgenic effects
Lanadelumab or berotralstat may be an option for the prevention of recurrent attacks of hereditary
dose of IM injection of adrenaline for child up to 6 months
100-150mcg
dose of IM adrenaline for child 6 months to 5 yrs
150mcg
dose of IM adrenaline for child 6-11 yrs
300mcg
dose of IM adrenaline for child 12-17 yrs& adults
500mcg
