Allergic Reactions

Question 1

role of epi in anaphylaxis

Answer 1

alpha effects vasoconstrict to reverse hypotension

beta-2 stimulation bronchodilates and inhibits mediator release by increasing cAMP in mast cells and basophils

Question 2

pathophys of anaphylaxis

Answer 2

• requires prior exposure
• Ags attach to IgE to form Ab-Ag complex
• complex attaches to wall of mast cell–>histamine release

Question 3

anaphylactoid rxn

Answer 3

• antibodies not required to release histamine
• Ags attach to mast cells and release histamine without binding first to antibody

Question 4

Effect of histamine

Answer 4

• pulmonary vasoconstriction, systemic vasodilation
• urticaria, erythema, bronchospasm, laryngeal edema, hypotension, CV collapse

Question 5

Treatment of anaphylaxis

Answer 5

• ABC/CPR
• 1-3 L crystalloid
• epi 10 ug IV increments for hypotension, 0.5-1 mg in cardiac arrest (relaxes bronchial smooth muscle, inhibits release of histamine)
• antihistamines (benadryl 0.5 mg/kg) don’t prevent histamine release, but compete with histamine receptor and attenuate its effects

Question 6

Histamine receptors

Answer 6

H1: stim results in bronchoconstriction (benadryl)

H2: Stim results in acid production by parietal cells and CV effects (cimetidine, ranitidine)

Question 7

Side effects of cimetidine

Answer 7

• bradycardia, arrhythmia, cardiac arrest have occurred after both po and IV cimetidine
• inhibits liver mixed func oxidase system
• confusion/hallucinations

Question 8

Latex allergy

Answer 8

• anaphylactic (IgE/skin testing) and anaphylactoid
• allergens are water soluble proteins in rubber
• Ag exposure thru: skin, mucous membranes, inhalation, IV

Question 9

Latex allergy: population

Answer 9

• healthcare workers
• spina bifida
• congenital urologic abnormalities
• atopy-esp rubber glvoes/bananas
• rubber industry workers

No relationship with antibiotic admin or anesthetic administration

Pretreatment with steroids/H1-H2 blockers do not matter

Question 10

Vancomycin reaction

Answer 10

• Gram positive cocci, including MRSA
• PCN/cephalosporin allergy

Question 11

Vancomycin toxicity

Answer 11

• local phlebitis
• red man
• acute chest pain
• ototoxicity (levels >60mg/L for several days)
• nephrotoxicity
• neutropenia

Question 12

Red Man’s Syndrome

Answer 12

• rapid infusion and histamine release
• flushing of face and neck, pruritis, hypotension
• fever uncommon
• slow IV admin of drug is key to prevention

admin over >30 min