Anaphylactic Shock ManagementAlamsyah Ambo Ala HusainDept. of Anestehsiology, Intensive Care and Pain ManagementMedical Faculty University of Hasanuddin*

Anaphylaxis*Anaphylaxis is an acute, systemic, life-threatening, IgE-mediated allergic reaction that occurs in previously sensitized people when they are re exposed to the sensitizing antigen.

Anaphylactic ShockA type of distributive shock that results from widespread systemic allergic reaction to an antigenThis hypersensitive reaction is LIFE THREATENING

Etiology*Anaphylaxis is typically triggered by:Drugs (eg, -lactam antibiotics, insulin, streptokinase, allergen extracts)Foods (eg, nuts, eggs, seafood)Proteins (eg, tetanus antitoxin, blood transfusions)Animal venomsLatexPeanut and latex allergens may be airborne. History of atopy does not increase risk of anaphylaxis but increases risk of death when anaphylaxis occurs.

Pathophysiology*Interaction of antigen with IgE on basophils and mast cells :triggers release of histamine, leukotrienes, and other mediators that cause:diffuse smooth muscle contraction (bronchoconstriction, vomiting, diarrhea) and vasodilation with plasma leakage.

Anaphylactoid reactions: *These reactions are clinically indistinguishable from anaphylaxis but do not involve IgE and do not require prior sensitization. They occur via direct stimulation of mast cells or via immune complexes that activate complement. The most common triggers are iodinated radiographic radiopaque dye, aspirin, other NSAIDs, opioids, blood transfusions, Ig, and exercise.

Anaphylactic vs AnaphylactoidAnaphylactic - an immediate systemic reaction caused by rapid, IgE-mediated immune release of potent mediators from tissue mast cells and peripheral blood basophils

Anaphylactoid - immediate systemic reactions that mimic anaphylaxis but are caused by nonimmune-mediated release of mediators or complement activation

Symptoms and Signs*Symptoms typically involve :the skin, upper or lower airways, cardiovascular system, or GI tract. One or more areas may be affected, and symptoms do not necessarily progress, although each patient typically manifests the same reaction to subsequent exposure.

Symptoms and Signs*Symptoms range from mild to severe and include :

Symptoms and Signs*Signs include hypotension, tachycardia, urticaria, angioedema, wheezing, cyanosis, and syncope. Shock can develop within minutes, and patients may experience seizures, become unresponsive, and die. Cardiovascular collapse can occur without respiratory or other symptoms.

Features of anaphylaxisNeurologicDizziness, weakness, syncope, seizuresOcularPruritus, conjunctival injection, lacrimationUpper airwayNasal congestion, sneezing, hoarseness, stridor, oropharnygeal or laryngeal edema, cough, obstructionLower airwayDyspnea, bronchospasm, tachypnea, accessory muscle use, cyanosis, respiratory arrest*

Features of anaphylaxisCardiovascularTachycardia, hypotension, arrhythmias, myocardialischemia/infarction, cardiac arrestSkinFlushing, erythema, pruritus, urticaria, angioedema,maculopapular rashGastrointestinalNausea, vomiting, abdominal pain, diarrhea

Reproduced with permission from STA Communications Inc. (Allergy & Asthma2000;13[3]:23-35).*

Differential diagnosis of anaphylaxisAcute respiratory decompensationSevere asthma, foreign body aspiration, pulmonary embolismLoss of consciousnessVasovagal reaction, seizure disorder, myocardial infarction and/or arrhythmias*

Differential diagnosis of anaphylaxisDisorders resembling anaphylaxisSystemic mastocytosis, carcinoid syndrome, Chinese restaurant syndrome (monosodium glutamate [MSG] ingestion), scombroid fish ingestion, pheochromocytoma, hereditary angioedema*

Differential diagnosis of anaphylaxis

Nonorganic diseasesHyperventilation syndrome, panic attacks, vocal cord dysfunction,

Reproduced with permission from STA Communications Inc. (Allergy & Asthma 2000;13[3]:23-35).*

Diagnosis*Diagnosis is clinical. Risk of rapid progression to shock leaves no time for testingAlthough mild equivocal cases can be confirmed by laboratory measurement 24-h urinary levels of N-methylhistamine orserum levels of tryptase.

Management Anaphylactic ShockEarly Recognition, treat aggressively AIRWAY SUPPORTIV EPINEPHRINE (open airways)AntihistaminesCorticosteroids IMMEDIATE WITHDRAWAL OF ANTIGEN IF POSSIBLEPREVENTION

Shock is a severe condition that occurs when not enough blood flows through the body, causing very low blood pressure, a lack of urine, and cell and tissue damage. Shock

Treatment*Epinephrine given immediatelySometimes intubationIV fluids and vasopressors for hypotensionAntihistamines (AH1 and AH2)Inhaled -agonists for bronchoconstrictionCorticosteroids

Epinephrine 1*is the cornerstone of treatment and should be given immediately. It can be given sc or IM Usual dose is 0.3 to 0.5 mL of a 1:1000 solution in adults or 0.01 mL/kg in children, (repeated every 10 to 30 min); maximal absorption occurs when the drug is given IM in the lateral thigh.

Epinephrine 2*Patients with cardiovascular collapse or severe airway obstruction may be given epinephrine IV in:a single dose (3 to 5 mL of a 1:10,000 solution over 5 min) or by continuous drip (1 mg in 250 mL 5% D/W for a concentration of 4 g/mL, starting at 1 g/min up to 4 g/min [15 to 60 mL/h]).

Epinephrine 3*Epinephrine may also be given by: sublingual injection (0.5 mL of 1:1000 solution) orendotracheal tube (3 to 5 mL of a 1:10,000 solution diluted to 10 mL with saline). A 2nd injection of epinephrine sc may be needed. Glucagon 1-mg bolus followed by 1-mg/h infusion should be used in patients taking oral -blockers, which attenuate the effect of epinephrine.

*Patients who have stridor and wheezing unresponsive to epinephrine should be given O2 and be intubated. Early intubation is recommended because waiting for a response to epinephrine may allow upper airway edema to progress sufficiently to prevent endotracheal intubation and require cricothyrotomy.

*Hypotension can usually be treated with 1 to 2 L (20 to 40 mL/kg in children) of isotonic IV fluids (eg, 0.9% saline).Hypotension refractory to fluids and IV epinephrine may require vasopressors (eg, dopamine 5 g/kg/min).

*Antihistaminesboth AH1 and AH2 should be given until symptoms resolve.H1 blockers (eg, diphenhydramine 50 to 100 mg IV) q4hH2 blockers (eg, cimetidine 300 mg IV or ranitidine 50 mg IV) q8h. Inhaled -agonists are useful for managing bronchoconstriction; albuterol 5 to 10 mg by continuous nebulization can be given.Corticosteroids have no proven role but may help prevent late-phase reaction in 4 to 8 h; methylprednisolone 125 mg IV initially is adequate.

Early treatment with administration of medications is recommendedPatients who do not appear to have life threatening symptoms on initial presentation may progress to life threatening anaphylaxisMediator release may be prolonged, producing biphasic anaphylaxisSome patients have a late or second phase of anaphylaxis, even after complete resolution of the first responsePatients who receive epinephrine for the treatment of anaphylaxis may not improve sufficiently or may improve and then relapse

Be preparedIdentify those at riskTraining in recognitionPosters in operating roomGuidelines in treatmentGuidelines for investigationDrugs for the immediate treatment of an anaphylactic reaction should always easily availableKits for blood sampling readily available

Prevention*Primary prevention is avoidance of known triggers. Desensitization is used for allergen triggers that cannot reliably be avoided (eg, insect stings). Patients with past reactions to radiopaque dye should not be reexposed; when exposure is absolutely necessary, patients are given 3 doses of prednisone 50 mg po q 6 h, starting 18 h before the procedure, and diphenhydramine 50 mg po 1 h before the procedure; however, no evidence supports the efficacy of this approach.

Prevention*Patients with an anaphylactic reaction to insect stings, foods, or other known substances should wear an alert bracelet and carry a prefilled epinephrine syringe (containing 0.3 mg for adults and 0.15 mg for children) for prompt self-treatment after exposure.

Thank you and be careful

Fact or fiction true or false?* Adrenaline should not be given to patients with anaphylaxis who are pregnant, elderly, or taking -blockers or -blockers (T/F)

Intravenous bolus injection of adrenaline is safe (T/F)

Even in an emergency department (where intravenous infusion is an option), intramuscular injection of adrenaline is an appropriate first-line treatment for anaphylaxis (T/F)

Answer*False. Although some caution with the dose may be wise, the overriding concern is that hypoxia or poor tissue perfusion will lead to ischaemia of critical organs (or harm the fetus).

False. This is how lethal errors are made. Even the correct dose can cause severe side effects. A controlled infusion is much safer, better tolerated and more efficacious, as a sustained therapeutic concentration is obtained.

True. Adrenaline given into the lateral thigh can result in useful serum levels of adrenaline within 35 minutes the time that may be required to get intravenous access and start an infusion. In many cases, intramuscular adrenaline is effective on its own.

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