Allergic Reactions & Anaphylaxis

Incidence In USA to 800 deaths/year In USA to 800 deaths/year Parenterally administered penicillin accounts for 100 to 500 deaths per year Parenterally administered penicillin accounts for 100 to 500 deaths per year Hymenoptera stings account for 40 to 100 deaths per year Hymenoptera stings account for 40 to 100 deaths per year Risk factors: beta-blockers, adrenal insufficiency Risk factors: beta-blockers, adrenal insufficiency

Causes of Deaths Laryngeal edema and acute bronchospasm with respiratory failure account for >70% Laryngeal edema and acute bronchospasm with respiratory failure account for >70% Circulatory collapse accounts for 25% Circulatory collapse accounts for 25% Other <5% - ?brain ?MI Other <5% - ?brain ?MI

Allergic Reaction  Physiologic response to antigens  Physiologic response to antigens Oversensitive response = allergicOversensitive response = allergic Occurs after sensitization to antigenOccurs after sensitization to antigen Antigen binds with Antibody Antigen binds with Antibody Less severe reaction from the inflammatory responseLess severe reaction from the inflammatory response

Allergic Reactions Generally classified into 3 groups: Generally classified into 3 groups: Mild allergic reactionMild allergic reaction Moderate allergic reactionModerate allergic reaction Severe allergic reaction (anaphylaxis)Severe allergic reaction (anaphylaxis)

Mild Allergic Reaction Characteristics Characteristics Urticaria (hives), itchyUrticaria (hives), itchy Erythema (redness)Erythema (redness) RhinitisRhinitis ConjunctivitisConjunctivitis Mild bronchoconstrictionMild bronchoconstriction Usually localized (look on abdomen, chest, back)Usually localized (look on abdomen, chest, back) No SOB or hypotension/hypoperfusion No SOB or hypotension/hypoperfusion Often self-treated at home Often self-treated at home

Urticaria

Moderate Allergic Reaction Characteristics Characteristics Mild signs/symptoms with any of following:Mild signs/symptoms with any of following: Dyspnea, possibly with wheezes Dyspnea, possibly with wheezes Angioneurotic edema Angioneurotic edema Systemic, not localized Systemic, not localized No hypotension/hypoperfusion No hypotension/hypoperfusion

Angioneurotic Edema

Severe Allergic Reaction (Anaphylaxis) Characteristics Characteristics Mild and/or moderate signs/symptoms plusMild and/or moderate signs/symptoms plus Shock / hypoperfusionShock / hypoperfusion Respiratory distressRespiratory distress

Anaphylaxis Manifestation of immediate hypersensitivity in which the exposure of a sensitized individual to a specific antigen results in life- threatening respiratory distress followed by vascular collapse and shock.

Pathophysiology Antigen Antigen Induces antibody formationInduces antibody formation ExamplesExamples Drugs (antibiotics) Drugs (antibiotics) Foods (nuts, shellfish) Foods (nuts, shellfish) Insect venoms Insect venoms Animal serum Animal serum Incompatible blood types Incompatible blood types

Pathophysiology Antigen enters body Antigen enters body Ingestion, absorption, inhalation, injectionIngestion, absorption, inhalation, injection Antibodies produced Antibodies produced Attach to surface of mast or basophil cells Attach to surface of mast or basophil cells Mast cells become sensitized Mast cells become sensitized

Pathophysiology Mast cells Mast cells In all subcutaneous/submucosal tissues,In all subcutaneous/submucosal tissues, Including conjunctiva, upper/lower respiratory tracts, and gutIncluding conjunctiva, upper/lower respiratory tracts, and gut Basophils Basophils Circulate in bloodCirculate in blood

Pathophysiology Antigen reenters body Antigen reenters body Attaches to antibodies on mast or basophil cells Attaches to antibodies on mast or basophil cells Mast cell degranulates, releases Mast cell degranulates, releases HistamineHistamine LeukotrienesLeukotrienes Slow reacting substance of anaphylaxis (SRS-A)Slow reacting substance of anaphylaxis (SRS-A) Eosinophil chemotactic factor (ECF)Eosinophil chemotactic factor (ECF)

Vasodilation Decreased peripheral vascular resistance Decreased peripheral vascular resistance Hypotension Hypotension Tachycardia Tachycardia Peripheral hypoperfusion Peripheral hypoperfusion

Increased Capillary Permeability Tissue edema, urticaria (hives), itching Tissue edema, urticaria (hives), itching Laryngeal edema Laryngeal edema Airway obstructionAirway obstruction Respiratory distressRespiratory distress StridorStridor Fluid leakage from vascular space Fluid leakage from vascular space Hypovolemic shockHypovolemic shock

Smooth Muscle Spasm Bronchospasm Bronchospasm Respiratory distressRespiratory distress “Tight Chest”“Tight Chest” WheezingWheezing GI Tract Spasm GI Tract Spasm Nausea, vomitingNausea, vomiting Cramping, diarrheaCramping, diarrhea Bladder Spasm Bladder Spasm Urinary urgency Urinary incontinence

Presentation Dependent on: Dependent on: Degree of hypersensitivityDegree of hypersensitivity Quantity, route, rate of antigen exposureQuantity, route, rate of antigen exposure Pattern of mediator releasePattern of mediator release Target organ sensitivity and responsivenessTarget organ sensitivity and responsiveness

Presentation Severity varies from mild to fatal Severity varies from mild to fatal Most reactions are respiratory, dermatologic Most reactions are respiratory, dermatologic Less severe early findings may progress to life-threatening over a short time Less severe early findings may progress to life-threatening over a short time Initial signs/symptoms do NOT necessarily correlate with severity, progression, duration of response Initial signs/symptoms do NOT necessarily correlate with severity, progression, duration of response Generally, quicker symptoms = more severe reactions Generally, quicker symptoms = more severe reactions

Presentation First manifestations involve skin First manifestations involve skin Warmth and tingling of the face, mouth, upper chest, palms and/or soles, or site of exposureWarmth and tingling of the face, mouth, upper chest, palms and/or soles, or site of exposure ErythemaErythema Pruritus is universal feature, erythemaPruritus is universal feature, erythema May be accompanied by generalized flushing, urticaria, nonpruritic angioedemaMay be accompanied by generalized flushing, urticaria, nonpruritic angioedema

Presentation May progress to involvement of respiratory system May progress to involvement of respiratory system coughcough chest tightnesschest tightness dyspneadyspnea wheezingwheezing throat tightnessthroat tightness dysphagiadysphagia hoarsenesshoarseness

Presentation Other Signs and Symptoms Other Signs and Symptoms lightheadedness or syncope caused by hypotension or dysrhythmialightheadedness or syncope caused by hypotension or dysrhythmia nasal congestion and sneezingnasal congestion and sneezing ocular itching and tearingocular itching and tearing cramping abdominal pain with nausea,vomiting, or diarrheacramping abdominal pain with nausea,vomiting, or diarrhea bowel or bladder incontinencebowel or bladder incontinence decreased level of consciousnessdecreased level of consciousness

Physical Exam Findings may include: Findings may include: urticaria, angioedema, rhinitis, conjunctivitisurticaria, angioedema, rhinitis, conjunctivitis tachypnea, tachycardia, hypotensiontachypnea, tachycardia, hypotension laryngeal stridor, hypersalivation, hoarseness, angioedemalaryngeal stridor, hypersalivation, hoarseness, angioedema

Patient Care ABCsMedics EpiPen for anaphylaxsis Position of comfort Oxygen Calm & reassure the patient Transport

ALS Indicators Unstable vital signs Unstable vital signs EpiPen use EpiPen use Respiratory Distress Respiratory Distress Signs & symptoms of shock: Signs & symptoms of shock: Poor skin signsPoor skin signs Sustained tachycardiaSustained tachycardia HypotensionHypotension