anaphylaxis management Flashcards
what is anapylaxis
systemic type 1 life threatening hypersensitivity reaction involving sudden IgE mediated release of histamine mediators from mastic ells and basophils
what is anaphylactic shock
distributive shock that results from anaphylaxis
what is an anaphylactoid reaction
a severe pseudoallergic reaction with symptoms that mimic anaphylaxis
not IgE mediated
caused by direct mast cell degranulation eg. due to vancomycin, radiocontrast media or opioid use) or complement mediated mast cell degranulation
typical symptoms of anaphylaxis and anaphylactoid reactions
acute onset of:
hives
angiodema
stridor
dyspnoea
bronchospasm
circulatory failure (distributive shock)
vomiting
diarrhoea
acute management checklist
get help, call cardiac arrest team
administer Im epinephrine
remove allergen
check HR and BP
do not allow patient to stand or walk, position supine
give high flow oxygen via non-rebreather
A-E assessment - secure the airway
cotinuous cardiac monitoring and pulse ox
Iv fluid boluses
what to administer
IM adrenaline
10mcg/kg
use adrenaline autoinjector if more readily available
if patient remains symptomatic, repeat every five minutes as needed
what concentration should IM adrenaline be
Epinephrine injections for anaphylaxis should always be given intramuscularly in a concentration of 1:1,000 (as opposed to the 1:10,000 solution used in cardiac arrest). Injecting the 1:1,000 solution into a vein can lead to cardiac arrhythmia/arrest.
what to do for the shocked and hypotensive patient
inform seior doctor
insert large bore Iv cannula
rapid IV bolus of sodium chloride
20ml/kg 0.9% saline
repeat as necessary
adrenaline infusion if still hypotensive after 40ml/kg sodium chloride
admit
if the symptoms resolve
observe for minimum 4 hours after last adrenaline done (admit to ED short stay unit or inpatient ward)
monitr for symptoms and signs of anaphylaxis
provide education and anaphylaxis action plan
discharge with adrenaline autoinjector
additional measures
nebulised adrenalne for upper airway obstruction
inhaled sabutamol for persistant wheeze
signs of shock
insert two large IV cannulae and give an 20ml/kg sodium chloride bolus
asess response and repeat as necessary
commence an adrenaline infusion if the patient remains hypotensive, administration via central venous access is preferred
critical care referral
signs of airway compromise
nebulised adrenaline or adrenaline infusion
early anaesthesia or ENT consult for awake fiberoptic intubation or surgical airway management
signs of respiratory failure or complete airway obstruction
perform rapid sequence intubation
induction agent ketamine is preferred
follow a difficult airway algorithm eg. using adjusts like videolaryngoscopy and/or gum elastic bougie
why is ketamine preferred for RSI for anaphylactic patients
It has bronchodilatory properties and does not affect hemodynamics. Propofol should be avoided in hypotensive patients as it can lower blood pressure.
signs of persistent wheeze
for severe bronchoscpasm give SABA eg. salbutamol or albuterol metered dose inhaler (MDI) via spacer or salbutamol/albuterol nebuliser
consider repeating IM adrenaline
consider adrenaline infusion
anaphylactic shock refractory to IV epinephrine infusion
administer IV glucagon, especially if the patient is on a beta blocker
consider other vasopressors eg. vasopressin, norepinephrine, dopamine, and phenylephrine
ensure adequate fluid status (vasopressors are less likely to work if fluid status is not optimised)
consider consulting ECMO team if above measures fail
where to admit the patient
all patients who have recieved Im adrenaline must be observed for a minimum of 4 hours after the last dose of adrenaline
have a low threshold to admit overnight if pateint presents in the late evening
admit to PCC if adrenaline infusion is required
at discharge
prescribe (PBS authority) two adrenaline autoinjectors
epipen - 300mcg
Anapen - 500mcg (if above 50kg)
autoinjector use advice
consider immunology referral
how to inject epipen
form fist around epipen and pull off safety release
place orange end on outer mid thigh (with or without clothing)
push down hard until click is heard or felt
hold for three seconds
remove pen
oropharyngeal airwaay
guedel
used to relieve soft palate obstruction
should only be used in unconscious patients otherwise it is poorly tolerated and may induce gagging and asppiration
how to insert a guedel
open the patients mouth and insure ther is no foreign body
insert oropharyngeal airway directly
maintain head tilt chin lift or jaw thrust and assess the patency of the patients airway
nasopharyngeala airway
check the patency of the patients right nostril
lubricate the NPA
insert the airway bevel end first vertically along the floor of the nose with a slight twisssting action
role of antihistamine
can be used to treat skin symptoms once the patient is stabilised
laboratory studies
not routinely indicated but can be useful to confirm anaphylaxis
serum mast cell tryptase (MCT): if elevated, this supports the diagnosis of anaphylaxis
normal result does not rule out anaphylaxis
low sensitivity especially in food triggered reaction
What is Type I hypersensitivity?
Immediate hypersensitivity involving preformed IgE antibodies coating mast cells and basophils being cross linked by contact with a free antigen. cell degranulation results in histamine release
Examples include allergic reactions, anaphylaxis, food allergies, and asthma.
List examples of Type I hypersensitivity reactions.
- Allergic or anaphylactic transfusion reactions
- Anaphylaxis
- Drug reactions (e.g., penicillin)
- Food allergies (e.g., nuts, shellfish)
- Insect venom allergies (e.g., bee, wasp)
- Reactions to environmental allergens (e.g., dust mites, pollen)
These reactions can manifest in various ways, including asthma and allergic rhinitis.
What characterizes Type II hypersensitivity?
Cytotoxic reactions mediated by IgM or IgG antibodies binding to antigens on cells of particular tissue types
This leads to complement activation and lysis of cells.
List examples of Type II hypersensitivity reactions.
destruction of cells:
* Acute hemolytic transfusion reaction
* Autoimmune haemolytic anemia
* haemolytic disease of the newborn
* Immune thrombocytopenia (ITP)
* Drug-induced neutropenia
inflammation:
* good pasture syndrome
* rheumatic fever
impaired cellular function
* Graves disease
* Myasthenia gravis
What is the mechanism of Type III hypersensitivity?
IgG antibodies bind to circulating antigens, forming immune complexes which deposit into tissues
These complexes deposit in tissues, activating complement and attracting neutrophils.
List examples of Type III hypersensitivity reactions.
- Serum sickness
- Arthus reaction
- Drug-induced hypersensitivity vasculitis
- Systemic lupus erythematosus (SLE)
- IgA nephropathy, membranous nephropathy, post strep GN
These reactions involve immune complex formation and tissue damage.
What defines Type IV hypersensitivity?
Delayed hypersensitivity mediated by presensitized T lymphocytes
This includes both CD4+ and CD8+ T cell responses.
List examples of Type IV hypersensitivity reactions.
- acute and chronic transplant rejection
- Graft-versus-host disease
- Contact dermatitis (e.g., poison ivy, nickel)
- Drug reactions (e.g., Stevens-Johnson syndrome)
- Multiple sclerosis
- Hashimoto’s thyroiditis
- rheumatoid arthritis
- T1DM
These reactions can take hours to days to develop and involve T cell-mediated responses.
Fill in the blank: Type III hypersensitivity involves the formation of _______ that deposit in tissues.
[immune complexes]
how to remember the hypersensitivity reactions
ACID
1: Allergic/anaphylactic/atopic
2: Cytotoxic
3: Immune complex
4: Delayed
biphasic anaphylactic reactions
recurrence of anaphylaxis symptoms despite initially successful treatment and without re-exposure to an antigen, most commonly <8 hours
