The MC presentations of anaphylaxis (>90% of cases)
cutaneous manifestations
Flushing, urticaria, pruritus, and, in high concentrations, hypotension and tachycardia
Histamine
Bronchoconstriction and increased microvascular permeability
cysteinyl leukotrienes and prostaglandin D2
Cutaneous flushing and attracts eosinophils and basophils to the site of mast cell activation
prostaglandin D2
Correlate with anaphylaxis severity
inversely proportional to the constitutive level of PAF acetylhydrolase, which is necessary for PAF inactivation
serum platelet activating factor (PAF)
Can activate complement and coagulation pathways
Activation of these pathways results in production of the anaphylotoxins, C3a and C5a, and activation of the kallikrein-kinin system, which regulates blood pressure and vascular permeability
Tryptase and Chymase
the actions of these anaphylactic mediators are likely additive or synergistic at the target tissues
Associated with radiocontrast sensitivity, exercise-induced anaphylaxis, idiopathic anaphylaxis, and allergy to foods or latex
ATOPY
not generally thought to be a risk factor for anaphylaxis from drug reactions or Hymenoptera stings
Can be a presenting feature of underlying systemic mastocytosis
Severe Hymenoptera-induced anaphylaxis (generally with prominent hypotension)
Has an extremely short half-life with a measurable time-window that expires <1 h from the onset of anaphylaxis
Histamine
More practical and useful biomarker
Peaks 60–90 min after the onset of anaphylaxis
Can be measured as long as 5 h after the onset of anaphylaxis
Serum TRYPTASE
Treatment of choice for anaphylaxis
Intramuscular administration of 0.3–0.5 mL of 1:1000 (1 mg/mL) epinephrine, with repeated doses at 5- to 20-min intervals - as needed for a severe reaction
Epinephrine can further accelerate empty ventricle syndrome due to its chronotropic effects thus recommended that patients who suffer from anaphylaxis be placed in this position before receiving epinephrine
SUPINE
These could lead to more RAPID DECOMPENSATION from anaphylaxis
Preexisting asthma and underlying cardiovascular disease
