Allergic Reactions & Allergic Reactions & AnaphylaxisAnaphylaxis

IncidenceIncidence In USA - 400 to 800 deaths/yearIn USA - 400 to 800 deaths/year Parenterally administered penicillin Parenterally administered penicillin

accounts for 100 to 500 deaths per accounts for 100 to 500 deaths per yearyear

Hymenoptera stings account for 40 Hymenoptera stings account for 40 to 100 deaths per yearto 100 deaths per year

Risk factors: beta-blockers, adrenal Risk factors: beta-blockers, adrenal insufficiencyinsufficiency

Causes of DeathsCauses of Deaths Laryngeal edema and acute Laryngeal edema and acute

bronchospasm with respiratory bronchospasm with respiratory failure account for >70%failure account for >70%

Circulatory collapse accounts for Circulatory collapse accounts for 25%25%

Other <5% - ?brain ?MIOther <5% - ?brain ?MI

Allergic ReactionAllergic Reaction

Physiologic response to antigensPhysiologic response to antigens• Oversensitive response = allergicOversensitive response = allergic• Occurs after sensitization to Occurs after sensitization to

antigenantigen Antigen binds with AntibodyAntigen binds with Antibody

• Less severe reaction from the Less severe reaction from the inflammatory response inflammatory response

Allergic ReactionsAllergic Reactions

Generally classified into 3 groups:Generally classified into 3 groups:• Mild allergic reactionMild allergic reaction• Moderate allergic reactionModerate allergic reaction• Severe allergic reaction Severe allergic reaction

(anaphylaxis)(anaphylaxis)

Mild Allergic ReactionMild Allergic Reaction CharacteristicsCharacteristics

• Urticaria (hives), itchyUrticaria (hives), itchy• Erythema (redness)Erythema (redness)• RhinitisRhinitis• ConjunctivitisConjunctivitis• Mild bronchoconstrictionMild bronchoconstriction• Usually localized (look on abdomen, Usually localized (look on abdomen,

chest, back)chest, back) No SOB or hypotension/hypoperfusionNo SOB or hypotension/hypoperfusion Often self-treated at homeOften self-treated at home

UrticariaUrticaria

Moderate Allergic ReactionModerate Allergic Reaction

CharacteristicsCharacteristics• Mild signs/symptoms Mild signs/symptoms withwith any of any of

following:following: Dyspnea, possibly with wheezesDyspnea, possibly with wheezes Angioneurotic edemaAngioneurotic edema Systemic, not localizedSystemic, not localized

No hypotension/hypoperfusionNo hypotension/hypoperfusion

Angioneurotic EdemaAngioneurotic Edema

Severe Allergic Reaction Severe Allergic Reaction (Anaphylaxis)(Anaphylaxis)

CharacteristicsCharacteristics• Mild and/or moderate Mild and/or moderate

signs/symptoms plussigns/symptoms plus• Shock / hypoperfusionShock / hypoperfusion• Respiratory distressRespiratory distress

AnaphylaxisAnaphylaxis

Manifestation of immediate Manifestation of immediate hypersensitivity in which the hypersensitivity in which the

exposure of a sensitized individual to exposure of a sensitized individual to a specific antigen results in life-a specific antigen results in life-threatening respiratory distress threatening respiratory distress

followed by vascular collapse and followed by vascular collapse and shock.shock.

PathophysiologyPathophysiology

AntigenAntigen• Induces antibody formationInduces antibody formation• ExamplesExamples

Drugs (antibiotics)Drugs (antibiotics) Foods (nuts, shellfish)Foods (nuts, shellfish) Insect venomsInsect venoms Animal serumAnimal serum Incompatible blood typesIncompatible blood types

PathophysiologyPathophysiology

Antigen enters bodyAntigen enters body• Ingestion, absorption, inhalation, Ingestion, absorption, inhalation,

injectioninjection Antibodies producedAntibodies produced Attach to surface of mast or basophil Attach to surface of mast or basophil

cellscells Mast cells become sensitizedMast cells become sensitized

PathophysiologyPathophysiology Mast cellsMast cells

• In all subcutaneous/submucosal In all subcutaneous/submucosal tissues, tissues,

• Including conjunctiva, upper/lower Including conjunctiva, upper/lower respiratory tracts, and gutrespiratory tracts, and gut

BasophilsBasophils• Circulate in bloodCirculate in blood

PathophysiologyPathophysiology

Antigen reenters bodyAntigen reenters body Attaches to antibodies on mast or basophil Attaches to antibodies on mast or basophil

cellscells Mast cell degranulates, releasesMast cell degranulates, releases

• HistamineHistamine• LeukotrienesLeukotrienes• Slow reacting substance of anaphylaxis Slow reacting substance of anaphylaxis

(SRS-A)(SRS-A)• Eosinophil chemotactic factor (ECF)Eosinophil chemotactic factor (ECF)

VasodilationVasodilation

Decreased peripheral vascular Decreased peripheral vascular resistanceresistance

HypotensionHypotension TachycardiaTachycardia Peripheral hypoperfusionPeripheral hypoperfusion

Increased Capillary PermeabilityIncreased Capillary Permeability

Tissue edema, urticaria (hives), Tissue edema, urticaria (hives), itchingitching

Laryngeal edemaLaryngeal edema• Airway obstructionAirway obstruction• Respiratory distressRespiratory distress• StridorStridor

Fluid leakage from vascular spaceFluid leakage from vascular space• Hypovolemic shockHypovolemic shock

Smooth Muscle SpasmSmooth Muscle Spasm

BronchospasmBronchospasm• Respiratory Respiratory

distressdistress• ““Tight Chest” Tight Chest” • WheezingWheezing

GI Tract SpasmGI Tract Spasm• Nausea, vomitingNausea, vomiting• Cramping, Cramping,

diarrheadiarrhea

Bladder SpasmBladder Spasm• Urinary urgencyUrinary urgency• Urinary Urinary

incontinenceincontinence

PresentationPresentation

Dependent on:Dependent on:• Degree of hypersensitivityDegree of hypersensitivity• Quantity, route, rate of antigen Quantity, route, rate of antigen

exposureexposure• Pattern of mediator releasePattern of mediator release• Target organ sensitivity and Target organ sensitivity and

responsivenessresponsiveness

PresentationPresentation

Severity varies from mild to fatalSeverity varies from mild to fatal Most reactions are respiratory, Most reactions are respiratory,

dermatologicdermatologic Less severe early findings may progress Less severe early findings may progress

to life-threatening over a short timeto life-threatening over a short time Initial signs/symptoms do Initial signs/symptoms do NOTNOT necessarily necessarily

correlate with severity, progression, correlate with severity, progression, duration of responseduration of response

Generally, quicker symptoms = more Generally, quicker symptoms = more severe reactionssevere reactions

PresentationPresentation First manifestations involve skinFirst manifestations involve skin

• Warmth and tingling of the face, Warmth and tingling of the face, mouth, upper chest, palms and/or mouth, upper chest, palms and/or soles, or site of exposuresoles, or site of exposure

• ErythemaErythema• Pruritus is Pruritus is universaluniversal feature, feature,

erythemaerythema• May be accompanied by generalized May be accompanied by generalized

flushing, urticaria, nonpruritic flushing, urticaria, nonpruritic angioedemaangioedema

PresentationPresentation May progress to involvement of May progress to involvement of

respiratory systemrespiratory system• coughcough• chest tightnesschest tightness• dyspneadyspnea• wheezingwheezing• throat tightnessthroat tightness• dysphagiadysphagia• hoarsenesshoarseness

PresentationPresentation Other Signs and SymptomsOther Signs and Symptoms

• lightheadedness or syncope caused lightheadedness or syncope caused by hypotension or dysrhythmiaby hypotension or dysrhythmia

• nasal congestion and sneezingnasal congestion and sneezing• ocular itching and tearingocular itching and tearing• cramping abdominal pain with cramping abdominal pain with

nausea,vomiting, or diarrheanausea,vomiting, or diarrhea• bowel or bladder incontinencebowel or bladder incontinence• decreased level of consciousnessdecreased level of consciousness

Physical ExamPhysical Exam Findings may include:Findings may include:

• urticaria, angioedema, rhinitis, urticaria, angioedema, rhinitis, conjunctivitisconjunctivitis

• tachypnea, tachycardia, tachypnea, tachycardia, hypotensionhypotension

• laryngeal stridor, hypersalivation, laryngeal stridor, hypersalivation, hoarseness, angioedemahoarseness, angioedema

Patient CarePatient Care

ABCsABCs

MedicsMedics

EpiPen for anaphylaxsisEpiPen for anaphylaxsis

Position of comfortPosition of comfort

OxygenOxygen

Calm & reassure the patientCalm & reassure the patient

TransportTransport

ALS IndicatorsALS Indicators

Unstable vital signsUnstable vital signs EpiPen useEpiPen use Respiratory DistressRespiratory Distress Signs & symptoms of shock:Signs & symptoms of shock:

• Poor skin signsPoor skin signs• Sustained tachycardiaSustained tachycardia• HypotensionHypotension