Immunological emergencies Flashcards
What is the difference between SJS and TEN?
Same disease but a continuum
SJS <10% of BSA
TEN >30% BSA
SJS/TEN overlap between 10-30%
What are the risk factors for developing SJS/TEN
HIV/AIDS infection
Active cancer (particularly lymphoma)
SLE
Women > men
Initiation of a medication (if on it for >8 weeks then risk «< less)
Age >65
What are the drugs with the highest rate of SJS?
Allopurinol
Aromatic Anti-epileptics
Sulfonamides
NSAIDS (meloxicam most)
Penicillins
Nevirapine
What are the other triggers for SJS
Mycoplasma pneumonia (most common cause in kids)
CMV
Idiopathic
Rare (vaccination, contrast, herbal meds)
What is the Nikolsky sign?
The ability to extend the area of superficial sloughing by applying gentle lateral pressure on the surface of the skin at an apparently uninvolved site
What layer of the skin does SJS/TENS affect?
The epidermis
What are the complications of SJS/TEN?
Similar to acute burns, treated similalrly
Hypovolaemia with shock
Renal failure
Bacteraemia
Electrolyte shifts
Hypercatabolic state
Multi-organ failure
GI bleeding/perforation
Pneumonia/ARDS
DIC
What are the exam and history of SJS/TENS?
Exposure commonly 1-4 weeks prior (average 14 days)
Acute febrile illness and malaise
Targetoid symmetrical painful rash that progressess rapidly and develops into vesicles and bullae
Generalised mucositis (>90%)
What is the Absoe-Hansen sign (AKA indirect Nikolsky sign)
Extension of a blister to unblistered skin when lateral pressure is on the blister or next to it
What is Drug reaction with eosinophilia and systemic symptoms (DRESS)?
A severe adverse drug reaction that is prolonged in its course and may start weeks to months after exposure to a drug
It is characterised by skin rash, organ damage, lymphadenopathy, eosinophilia and lymphocytosis
It is often associated with reactivation of viruses from the Herpesviridae family (HSV, EBV, CMV etc)
What are the most common causes of DRESS?
High risk
- Aromatic antiepileptics
- Allopurinol
- Dapsone
- Sulfonamides
- RIPE anti-tuberculosis agents
- Vancomycin
Lower risk
- Beta lactams
- NSAID’s
What are the aromatic anticonvulsants?
Carbamazepine
Phenytoin
Lamotrigine
Phenobarbital
Oxcarbazepine
What are the risk factors for developing a biphasic anaphylactic reaction?
Severe initial symptoms (ie hypotension)
Delayed use of Adrenaline 60mins
Inadequate amount of Adrenaline
Unknown allergen
What is the basic management of Anaphylaxis in adults?
- Once recognised IM Adrenaline 0.5mg up to 2 doses 5mins apart
- After 2 doses convert to IV Adrenaline infusion
- If no IV access can continue IM until obtained, if patient severely unstable then give IM Adrenaline at least 5minutely if not sooner
- Once IV access obtained give IV adrenaline boluses 1mcg/kg in children or 50-100mcg in adults if unstable, can give as fast as 1min between doses
- Asthma symptoms treat for asthma
- Hypotension give IV fluids +/- other pressors
- Airway give Dexamethasone and IV/Neb adrenaline
How does arrest management algorithm change when it is known/highly suspected to be caused by anaphylaxis?
- Adrenaline every 2mins instead of every 4 mins
- Priority is early intubation with ETT or FONA
- Pending definitive airway consider ratio of 15:2 or less as principal issue is hypoxia
- Do not delay definitive airway as most anaphylactic arrests are from bronchospasm or airway swelling leading to hypoxia
- Unlikley to be in a shockable rhythm, consider rhythm checks without charging shock to save time
- Wide complex rhythms more likely AIVR and not VT, Amiodarone contraindicated and can be removed from the algorithm
