《心肺复苏指南》参考资料（英文版）Part 10-6 Anaphylaxis

Anaphylaxis is a severe, systemic allergic reaction char- fatal reaction occurs within 10 to 15 minutes. Cardiovas- acterized by multisystem involvement, including cular collapse is the most common mechanism. 3-5 skin, airway, vascular system, and gastrointestinal trac

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Part 10.6: Anaphylaxis A naphy laxis is a severe, systemic allergic reaction char- fatal reaction occurs within 10 to 15 minutes. Cardiovas- acterized by multisystem involvement, including the ular coll the most common mechanism. 3-5 kin, airway, vascular system, and gastrointestinal tract. Foods. Peanuts, tree-grown nuts, seafood, and wheat are the Severe cases may result in complete obstruction of the foods most frequently associated with life-threatening ana- airway, cardiovascular collapse, and death. The term classic phylaxis. 6 Bronchospasm and asphyxia are the most fre- anaphylaxis refers to hypersensitivity reactions mediated by quent mechanisms. 3-5 the subclass of antibodies immunoglobulins Ige and lgg Prior sensitization to an allergen has occurred, producing Signs and Symptoms antigen-specific immunoglobulins. Subsequent reexposure to Consider anaphylaxis when responses from 2 or more body systems(cutaneous, respiratory, cardiovascular, neurologic the allergen provokes the anaphylactic reaction. Many ana- or gastrointestinal) are noted; the cardiovascular and respira- phylactic reactions, however, occur without a documented tory systems may not be involved. The shorter the interval prior exposure. between exposure and reaction, the more likely the reaction is Anaphylactoid or pseudoanaphylactic reactions display a to be severe Signs and symptoms include the following similar clinical syndrome, but they are not immune-mediated Treatment for the two conditions is similar Serious upper airway (laryngeal) edema, lower airway edema(asthma), or both may develop, causing stridor and Pathophysiology wheezing. Rhinitis is often an early sign of respiratory The inciting allergen binds to antigen-specific IgE that has involvement accumulated on previously sensitized basophils and mast Cardiovascular collapse is the most common periarrest cells. These cells almost immediately release a series of manifestation. Vasodilation produces a relative hypovole mediators, including histamines, leukotrienes, prostaglandins mia. Increased capillary permeability contributes to further thromboxanes, and bradykinins. When released locally and intravascular volume loss. The patient may be agitated or systemically, these mediators cause increased mucous mem- anxious and may appear either flushed or pale. Additional brane secretions, increased capillary permeability and leak, cardiac dysfunction may result from underlying disease or and markedly reduced smooth muscle tone in blood vessels the development of myocardial ischemia from administra- (vasodilation) and bronchioles tion of epinephrine. 3-5 testinal signs and symptoms of anaphylaxis clude abdominal pain, vomiting, and diarrhea. Any antigen capable of activating IgE can be a trigger for anaphylaxis. In terms of etiology, researchers generally list Differential Diagnoses the following categories of causes: pharmacologic agents, A number of disease processes produce some of the signs and latex, stinging insects, and foods. In up to 5% of cases the symptoms of anaphylaxis. Only after the clinician eliminate antigenic agent cannot be identified anaphylaxis as a diagnosis should the other conditions considered, because failure to identify and appropriately treat Pharmacologic agents. Antibiotics (especially parenteral anaphylaxis can be fatal 7.8 penicillins and other B-lactams), aspirin and nonsteroidal anti-inflammatory drugs, and intravenous (IV)contrast Scombroid poisoning often develops within 30 minutes of agents are the most frequent medications associated with eating spoiled fish, including tuna, mackerel, or dolphin life-threatening anaphylaxis. (mahi-mahi). Typically scombroid poisoning presents with Latex. Much attention has focused on latex-induced anapl urticaria,nausea, vomiting, diarrhea, and headache. It is laxis, but it is actually quite rare. 2A decade-long registry treated with antihistamines of anaphylactic deaths in England has not registered any latex-associated deaths. 3, 4 Angioedema that seems to occur in families is termed Stinging insects. Fatal anaphylaxis has long been associated hereditary angioedema. This hereditary form is indisti with stings from hymenoptera(membrane-winged insects), guishable from the early angioedema of anaphylaxis or jackets. medication-related angioedema. Urticaria does not occur Fatal anaphylaxis can develop when a person with IgE with hereditary angioedema, however. Angioedema is antibodies induced by a previous sting is stung again. A treated with Cl esterase inhibitor replacement concentrate if available. Otherwise, fresh frozen plasma may be used Angiotensin-converting enzyme(ACE)inhibitors are asso- ( Circulation.2005:000:IV-143-IV-145. ciated with a reactive angioedema predominantly of the o 2005 American Heart Association upper airway. This reaction can develop days or years after This special supplement to Circulation is freely available at http://www.circulationaha.org ACE inhibitor therapy is begun. The best treatment for this form of angioedema is unclear, but aggressive early airway DOI: 10.1161/CIRCULATIONAHA. 105.166568 management Is critical. 9 ⅣV143

Part 10.6: Anaphylaxis Anaphylaxis is a severe, systemic allergic reaction characterized by multisystem involvement, including the skin, airway, vascular system, and gastrointestinal tract. Severe cases may result in complete obstruction of the airway, cardiovascular collapse, and death. The term classic anaphylaxis refers to hypersensitivity reactions mediated by the subclass of antibodies immunoglobulins IgE and IgG. Prior sensitization to an allergen has occurred, producing antigen-specific immunoglobulins. Subsequent reexposure to the allergen provokes the anaphylactic reaction. Many anaphylactic reactions, however, occur without a documented prior exposure. Anaphylactoid or pseudoanaphylactic reactions display a similar clinical syndrome, but they are not immune-mediated. Treatment for the two conditions is similar. Pathophysiology The inciting allergen binds to antigen-specific IgE that has accumulated on previously sensitized basophils and mast cells. These cells almost immediately release a series of mediators, including histamines, leukotrienes, prostaglandins, thromboxanes, and bradykinins. When released locally and systemically, these mediators cause increased mucous membrane secretions, increased capillary permeability and leak, and markedly reduced smooth muscle tone in blood vessels (vasodilation) and bronchioles. Etiology Any antigen capable of activating IgE can be a trigger for anaphylaxis. In terms of etiology, researchers generally list the following categories of causes: pharmacologic agents, latex, stinging insects, and foods. In up to 5% of cases the antigenic agent cannot be identified. Pharmacologic agents. Antibiotics (especially parenteral penicillins and other -lactams), aspirin and nonsteroidal anti-inflammatory drugs, and intravenous (IV) contrast agents are the most frequent medications associated with life-threatening anaphylaxis. Latex. Much attention has focused on latex-induced anaphylaxis, but it is actually quite rare.1,2 A decade-long registry of anaphylactic deaths in England has not registered any latex-associated deaths.3,4 Stinging insects. Fatal anaphylaxis has long been associated with stings from hymenoptera (membrane-winged insects), including ants, bees, hornets, wasps, and yellow jackets. Fatal anaphylaxis can develop when a person with IgE antibodies induced by a previous sting is stung again. A fatal reaction occurs within 10 to 15 minutes. Cardiovascular collapse is the most common mechanism.3–5 Foods. Peanuts, tree-grown nuts, seafood, and wheat are the foods most frequently associated with life-threatening anaphylaxis.6 Bronchospasm and asphyxia are the most frequent mechanisms.3–5 Signs and Symptoms Consider anaphylaxis when responses from 2 or more body systems (cutaneous, respiratory, cardiovascular, neurologic, or gastrointestinal) are noted; the cardiovascular and respiratory systems may not be involved. The shorter the interval between exposure and reaction, the more likely the reaction is to be severe. Signs and symptoms include the following: ● Serious upper airway (laryngeal) edema, lower airway edema (asthma), or both may develop, causing stridor and wheezing. Rhinitis is often an early sign of respiratory involvement. ● Cardiovascular collapse is the most common periarrest manifestation. Vasodilation produces a relative hypovolemia. Increased capillary permeability contributes to further intravascular volume loss. The patient may be agitated or anxious and may appear either flushed or pale. Additional cardiac dysfunction may result from underlying disease or the development of myocardial ischemia from administration of epinephrine.3–5 ● Gastrointestinal signs and symptoms of anaphylaxis include abdominal pain, vomiting, and diarrhea. Differential Diagnoses A number of disease processes produce some of the signs and symptoms of anaphylaxis. Only after the clinician eliminates anaphylaxis as a diagnosis should the other conditions be considered, because failure to identify and appropriately treat anaphylaxis can be fatal.7,8 ● Scombroid poisoning often develops within 30 minutes of eating spoiled fish, including tuna, mackerel, or dolphin (mahi-mahi). Typically scombroid poisoning presents with urticaria, nausea, vomiting, diarrhea, and headache. It is treated with antihistamines. ● Angioedema that seems to occur in families is termed hereditary angioedema. This hereditary form is indistinguishable from the early angioedema of anaphylaxis or medication-related angioedema. Urticaria does not occur with hereditary angioedema, however. Angioedema is treated with C1 esterase inhibitor replacement concentrate if available. Otherwise, fresh frozen plasma may be used. ● Angiotensin-converting enzyme (ACE) inhibitors are associated with a reactive angioedema predominantly of the upper airway. This reaction can develop days or years after ACE inhibitor therapy is begun. The best treatment for this form of angioedema is unclear, but aggressive early airway management is critical.9 (Circulation. 2005;000:IV-143-IV-145.) © 2005 American Heart Association. This special supplement to Circulation is freely available at http://www.circulationaha.org DOI: 10.1161/CIRCULATIONAHA.105.166568 IV-143

IV-144 Circulation December 13. 2005 Severe, near-fatal asthma attacks can present with broncho- Antihistamines. Administer antihistamines slowly IV or IM pasm and stridor. In general, asthma attacks do not present (eg, 25 to 50 mg of diphenhydramine) with urticaria or angioedema. Asthma treatment is very h, blockers. Administer h blockers such as cimetidine different from treatment of anaphylaxis even though the (300 mg orally, IM, or Iv). I6 echanism of immunologic hypersensitivity may be com- Inhaled B-adrenergic agents. Provide inhaled albuterol if mon to bronchospasm is a major feature. Inhaled ipratropium may be forms of panic disorder, functional stridor devel- especially useful for treatment of bronchospasm in patients ops as a result of forced adduction of the vocal cords In a receiving B-blockers. Note that some patients treated for panic attack there is no urticaria, angioedema, hypoxia, or near-fatal asthma actually had anaphylaxis, so they received hypotension repeated doses of conventional bronchodilators rather than Corticosteroids. Infuse high-dose IV corticosteroids early in vasovagal reactions in the course of therapy. Beneficial effects are delayed at least 4 to 6 hours Interventions to Prevent Removal of venom sac. Insect envenomation by bees(but Cardiopulmonary Arrest not wasps) may leave a venom sac attached to the victims Recommendations to prevent cardiopulmonary arrest are skin. At some point during initial assessment, look at the sting difficult to standardize because etiology, clinical presentation site,and if you see a stinger, immediately scrape it or any (including severity and course), and organ involvement vary insect parts at the site of the sting, using the dull edge of a widely. Few randomized trials of treatment approaches have knife IS Avoid compressing or squeezing any insect parts near been reported. Providers, however, must be aware that the the skin because squeezing may increase envenomation atient can deteriorate quick kly and that urgent support of airway, breathing, and circulation are essential. The following Potential Therapies therapies are commonly used and widely accepted but are Vasopressin. There are case reports that vasopressin may based more on consensus than evidence. benefit severely hypotensive patients. 9.20 Atropine. Case reports suggest that when relative or severe Oxygen. Administer oxygen at high flow rates. bradycardia is present, there may be a role for administra- Epinephrine tion of atropine. 8 Absorption and subsequent achievement of maximun Glucagon. For patients who are unresponsive to epineph- plasma concentration after subcutaneous administration is rine, especially those receiving B-blockers, glucagon may slower and may be significantly delayed with shock. 0. be effective. This agent is short-acting; give I to 2 mg Thus, intramuscular(IM)administration is favored. every 5 minutes IM or I. Nausea, vomiting, and hyper- Administer epinephrine by IM injection early to all glycemia are common side effects patients with signs of a systemic reaction, especially hypotension, airway swelling, or definite difficulty Observation Patients who respond to therapy require observation, but there Use an IM dose of 0.3 to 0.5 mg(1: 1000)repeated is no evidence to suggest the length of observation time every 15 to 20 minutes if there is no clinical needed. Symptoms may recur in some patients (up to 20%0) within I to 8 hours(biphasic response)despite an intervening Improvement. asymptomatic period. Biphasic responses have been reported -Administer IV epinephrine if anaphylaxis appears to be to occur up to 36 hours after the initial reaction. 15,16. A severe with immediate life-threatening manifestations Use epinephrine (1: 10 000)0.I mg Iv slowly over may be discharged. 25 Severity of reaction or other probler however, may necessitate longer periods of observation. olution before infusion An IV infusion at rates of I to 4 ug/min may Airway Obstruction prevent the need to repeat epinephrine injections Early elective intubation is recommended for patients ob- relop hoarseness, lingual edema, stridor, -Close monitoring is critical because fatal overdose of oropharyngeal swelling. Patients with angioedema pose a pinephrine has been reported 3.14 particularly worrisome problem because they are at high risk -Patients who are taking B-blockers have increased for rapid deterioration. Most will present with some degree of dence and severity of anaphylaxis and can develop a labial or facial swelling. Patients with hoarseness, lingual paradoxical response to epinephrine. Consider glucagon edema, and oropharyngeal swelling are at particular risk for as well as ipratropium for these patients(see below) Aggressive fluid resuscitation. Give isotonic crystalloid Patients can deteriorate over a brief period of time( to 3 (eg, normal saline) if hypotension is present and does not hours), with progressive development of stridor, dysphonia or respond rapidly to epinephrine. A rapid infusion of I aphonia, laryngeal edema, massive lingual swelling, facial 2 L or even 4 L may be needed initially and neck swelling, and hypoxemia. This may occur when

● Severe, near-fatal asthma attacks can present with bronchospasm and stridor. In general, asthma attacks do not present with urticaria or angioedema. Asthma treatment is very different from treatment of anaphylaxis even though the mechanism of immunologic hypersensitivity may be common to both. ● In some forms of panic disorder, functional stridor develops as a result of forced adduction of the vocal cords. In a panic attack there is no urticaria, angioedema, hypoxia, or hypotension. ● Along with anaphylaxis, consider vasovagal reactions. Urticaria, angioedema, and bronchospasm are not present in vasovagal reactions. Interventions to Prevent Cardiopulmonary Arrest Recommendations to prevent cardiopulmonary arrest are difficult to standardize because etiology, clinical presentation (including severity and course), and organ involvement vary widely. Few randomized trials of treatment approaches have been reported. Providers, however, must be aware that the patient can deteriorate quickly and that urgent support of airway, breathing, and circulation are essential. The following therapies are commonly used and widely accepted but are based more on consensus than evidence: ● Oxygen. Administer oxygen at high flow rates. ● Epinephrine –Absorption and subsequent achievement of maximum plasma concentration after subcutaneous administration is slower and may be significantly delayed with shock.10,11 Thus, intramuscular (IM) administration is favored. • Administer epinephrine by IM injection early to all patients with signs of a systemic reaction, especially hypotension, airway swelling, or definite difficulty breathing. • Use an IM dose of 0.3 to 0.5 mg (1:1000) repeated every 15 to 20 minutes if there is no clinical improvement. –Administer IV epinephrine if anaphylaxis appears to be severe with immediate life-threatening manifestations.12 • Use epinephrine (1:10 000) 0.1 mg IV slowly over 5 minutes. Epinephrine may be diluted to a 1:10 000 solution before infusion. • An IV infusion at rates of 1 to 4 g/min may prevent the need to repeat epinephrine injections frequently.13 –Close monitoring is critical because fatal overdose of epinephrine has been reported.3,14 –Patients who are taking -blockers have increased incidence and severity of anaphylaxis and can develop a paradoxical response to epinephrine.15 Consider glucagon as well as ipratropium for these patients (see below). Aggressive fluid resuscitation. Give isotonic crystalloid (eg, normal saline) if hypotension is present and does not respond rapidly to epinephrine. A rapid infusion of 1 to 2 L or even 4 L may be needed initially. Antihistamines. Administer antihistamines slowly IV or IM (eg, 25 to 50 mg of diphenhydramine). H2 blockers. Administer H2 blockers such as cimetidine (300 mg orally, IM, or IV).16 Inhaled -adrenergic agents. Provide inhaled albuterol if bronchospasm is a major feature. Inhaled ipratropium may be especially useful for treatment of bronchospasm in patients receiving -blockers. Note that some patients treated for near-fatal asthma actually had anaphylaxis, so they received repeated doses of conventional bronchodilators rather than epinephrine.17 Corticosteroids. Infuse high-dose IV corticosteroids early in the course of therapy. Beneficial effects are delayed at least 4 to 6 hours. Removal of venom sac. Insect envenomation by bees (but not wasps) may leave a venom sac attached to the victim’s skin. At some point during initial assessment, look at the sting site, and if you see a stinger, immediately scrape it or any insect parts at the site of the sting, using the dull edge of a knife.18 Avoid compressing or squeezing any insect parts near the skin because squeezing may increase envenomation. Potential Therapies ● Vasopressin. There are case reports that vasopressin may benefit severely hypotensive patients.19,20 ● Atropine. Case reports suggest that when relative or severe bradycardia is present, there may be a role for administration of atropine.8 ● Glucagon. For patients who are unresponsive to epinephrine, especially those receiving -blockers, glucagon may be effective. This agent is short-acting; give 1 to 2 mg every 5 minutes IM or IV. Nausea, vomiting, and hyperglycemia are common side effects. Observation Patients who respond to therapy require observation, but there is no evidence to suggest the length of observation time needed. Symptoms may recur in some patients (up to 20%) within 1 to 8 hours (biphasic response) despite an intervening asymptomatic period. Biphasic responses have been reported to occur up to 36 hours after the initial reaction.15,16,21–24 A patient who remains symptom-free for 4 hours after treatment may be discharged.25 Severity of reaction or other problems, however, may necessitate longer periods of observation. Airway Obstruction Early elective intubation is recommended for patients observed to develop hoarseness, lingual edema, stridor, or oropharyngeal swelling. Patients with angioedema pose a particularly worrisome problem because they are at high risk for rapid deterioration. Most will present with some degree of labial or facial swelling. Patients with hoarseness, lingual edema, and oropharyngeal swelling are at particular risk for respiratory compromise. Patients can deteriorate over a brief period of time (1⁄2 to 3 hours), with progressive development of stridor, dysphonia or aphonia, laryngeal edema, massive lingual swelling, facial and neck swelling, and hypoxemia. This may occur when IV-144 Circulation December 13, 2005

Part 10.6: Anaphylaxis IV-145 patients have a delayed presentation to the hospital or fail to References respond to therapy 1. Dreyfus DH, Fraser B, Randolph CC. Anaphylaxis to latex in patients At this point use of either the laryngeal mask airway or the without identified risk factors for latex allergy. Conn Med. 2004: 68: Combitube will be ineffective, and endotracheal intubation 217-222. and cricothyrotomy may be difficult or impossible. Attempts 2. Ownby DR. A history of latex allergy. J Allergy Clin Immunol. 2002; l10S27-S32 at endotracheal intubation may only further increase laryn 3. Pumphrey RS Lessons for management of anaphylaxis from a study geal edema or cause trauma to the airway. Early recognition fatal reactions. Clin Erp Allergy. 2000; 30: 1144-1150. of the potentially difficult airway allows planning for alter 4. Pumphrey RS Fatal anaphylaxis in the UK, 1992-2001. Novartis Found native airway management by those who are trained in these ymp.2004257:16-128; discussion I28-132,157-160.276-185 techniques, including consultation with anesthesia and an ear, 5. Pumphrey Rs, Roberts IS Postmortem findings after fatal anaphylactic actions. J Clin Pathol. 2000: 53: 273-276 nose, and throat specialist if the provider is unfamiliar with 6. Mullins RJ. Anaphylaxis: risk factors for recurrence. Clin Exp Allergy advanced airway techniques 7. Brown AF. Anaphylaxis: quintessence, quarrels, and quandaries. Emerg Arrest MedJ.2001;18:328 8. Brown AFT. Anaphylaxis gets the adrenaline going. Emerg Med J. If cardiac arrest develops, olume administration. and 2004:21:128-129. adrenergic drugs are the cornerstones of therapy. Critical 9. Shoo e, Shah uK, Grillone GA, Stram JR. Fuleiham NS. Predictin therapies are as follows airway risk in angioedema: staging system based on presentation. Oto- laryngol Head Neck Surg. 1999: 121: 263-268 Aggressive volume expansion. Near-fatal anaphylaxis pro- 10. Simons FE, Gu x, Simons K. Epinephrine absorption in adults: intra duces profound vasodilation that significantly increases muscular versus subcutaneous injection. J Allergy Clin Immunol 2001 08:871-873. intravascular capacity. Massive volume replacement is 11. Simons FE, Chan ES Gu X, Simons KJ. Epinephrine for the out-of needed, Use at least 2 large-bore IVs with pressure bags to treatment of anaphylaxis in infants: is the ampule administer large volumes(typically between 4 and 8 L)of yringe/needle method practical? J Allergy Clin Immunol. 2001: 108 isotonic crystalloid as quickly as possible High-dose epinephrine /V. Use a rapid progression to high 12. Brown SG. Blackman KE. Stenlake V, Heddle RJ. Insect sting ana phy laxis; prospective evaluation of treatment with intravenous adrenaline dose without hesitation in patients in full cardiac arrest. A and volume resuscitation. Emerg Med J. 2004: 21: 149-154 commonly used sequence is I to 3 mg IV (3 minutes), 3 to 13. Barach EM, Nowak RM, Lee TG, Tomlanovich MM. Epinephrine for 5 mg IV(3 minutes), then 4 to 10 ug/min infusion treatment of anaphylactic shock. JAMA. 1984: 251: 2118-2122 Antihistamine /v there is little data about the value of 14. Pumphrey R. Anaphylaxis: can we tell who is at risk of a fatal reaction? ntihistamines in anaphylactic cardiac arrest, but it is /s Curr Opin Allergy Clin Immunol. 2004; 4: 285-290 Ellis AK, Day JH. Diagnosis and management of anaphylaxis. CMA. reasonable to assume that little additional harm could 2003:169:307-311 result. Ib 16. Winbery SL, Lieberman PL. Histamine and antihistamines in an Steroid therapy. Steroids given during a cardiac arrest will 17. Rainbow I, Browne G]. Fatal asthma or anaphylaxis? Emerg Med J have little effect, but they may have value in the early hours 2002;19415-417 of 18. Visscher PK, Vetter RS, Camazine S. Removing bee stings. Lancet Asystole/Pulseless Electrical Activity(PEA) Algorithms 1996:348:301-302 The arrest rhythm in anaphylaxis is often PEA or asystole 19. Kill C, Wranze E, Wulf H. Successful treatment of severe anaphylactic See the ACls Pulseless Arrest Algorithm in Part 7.2 shock with vasopressin: two case reports. Int Arch Allergy Immunol. 2004:134:260-261 Management of cardiac arrest 20. williams SR, Denault AY, Pellerin M, Martineau R. Vasopressin for Prolonged CPR. Patients with anaphylaxis are often young treatment of shock following aprotinin administration. Can J Anaesth. 2004:51:169-172 with healthy hearts and cardiovascular systems, and they 21. Yocum MW, Butterfield JH. Klein JS, Volcheck Gw Schroeder DR, may respond to rapid correction of vasodilation and low Silverstein MD. Epidemiology of anaphylaxis in Olmsted County: a intravascular volume. Effective CPR may maintain suffi- population-based study. J Allergy Clin Immunol. 1999; 104(pt cient oxygen delivery until the catastrophic effects of the anaphylactic reaction resolve. 22. Smith PL, Kagey-Sobotka A, Bleecker ER, Traystman R, Kaplan AP. Valentine MD, Permutt S, Lichtenstein LM. Physiolog Summary manifestations of human anaphylaxis. J Clin Inest 1980: 66: 1072-1080 23. Stark BJ, Sullivan TJ. Biphasic and protracted anaphylaxis. J Allergy Clin The management of anaphylaxis includes early recognition, anticipation of deterioration, and aggressive support of air way, oxygenation, ventilation, and circulation. Potential fatal danger of biphasic anaphylactic reactions. J Accid Emerg Med. 1998: 15: complications include airway obstruction and cardiovascular 25. Brady wJ Jr, Luber S, Carter CT. Guertter A, Lindbeck G. Multiphasic collapse. Prompt, aggressive therapy may succeed even if anaphylaxis: an uncommon event in the emergency department. Acad cardiac arrest develo Emerg Med.19974:193-197

patients have a delayed presentation to the hospital or fail to respond to therapy. At this point use of either the laryngeal mask airway or the Combitube will be ineffective, and endotracheal intubation and cricothyrotomy may be difficult or impossible. Attempts at endotracheal intubation may only further increase laryngeal edema or cause trauma to the airway. Early recognition of the potentially difficult airway allows planning for alternative airway management by those who are trained in these techniques, including consultation with anesthesia and an ear, nose, and throat specialist if the provider is unfamiliar with advanced airway techniques. Cardiac Arrest If cardiac arrest develops, CPR, volume administration, and adrenergic drugs are the cornerstones of therapy. Critical therapies are as follows: ● Aggressive volume expansion. Near-fatal anaphylaxis produces profound vasodilation that significantly increases intravascular capacity. Massive volume replacement is needed. Use at least 2 large-bore IVs with pressure bags to administer large volumes (typically between 4 and 8 L) of isotonic crystalloid as quickly as possible. ● High-dose epinephrine IV. Use a rapid progression to high dose without hesitation in patients in full cardiac arrest. A commonly used sequence is 1 to 3 mg IV (3 minutes), 3 to 5 mg IV (3 minutes), then 4 to 10 g/min infusion. ● Antihistamine IV. There is little data about the value of antihistamines in anaphylactic cardiac arrest, but it is reasonable to assume that little additional harm could result.16 ● Steroid therapy. Steroids given during a cardiac arrest will have little effect, but they may have value in the early hours of any postresuscitation period. ● Asystole/Pulseless Electrical Activity (PEA) Algorithms. The arrest rhythm in anaphylaxis is often PEA or asystole. See the ACLS Pulseless Arrest Algorithm in Part 7.2: “Management of Cardiac Arrest.” ● Prolonged CPR. Patients with anaphylaxis are often young with healthy hearts and cardiovascular systems, and they may respond to rapid correction of vasodilation and low intravascular volume. Effective CPR may maintain sufficient oxygen delivery until the catastrophic effects of the anaphylactic reaction resolve. Summary The management of anaphylaxis includes early recognition, anticipation of deterioration, and aggressive support of airway, oxygenation, ventilation, and circulation. Potential fatal complications include airway obstruction and cardiovascular collapse. Prompt, aggressive therapy may succeed even if cardiac arrest develops. References 1. Dreyfus DH, Fraser B, Randolph CC. Anaphylaxis to latex in patients without identified risk factors for latex allergy. Conn Med. 2004;68: 217–222. 2. Ownby DR. A history of latex allergy. J Allergy Clin Immunol. 2002; 110:S27–S32. 3. Pumphrey RS. Lessons for management of anaphylaxis from a study of fatal reactions. Clin Exp Allergy. 2000;30:1144–1150. 4. Pumphrey RS. Fatal anaphylaxis in the UK, 1992–2001. Novartis Found Symp. 2004;257:116–128; discussion 128–132, 157–160, 276–185. 5. Pumphrey RS, Roberts IS. Postmortem findings after fatal anaphylactic reactions. J Clin Pathol. 2000;53:273–276. 6. Mullins RJ. Anaphylaxis: risk factors for recurrence. Clin Exp Allergy. 2003;33:1033–1040. 7. Brown AF. Anaphylaxis: quintessence, quarrels, and quandaries. Emerg Med J. 2001;18:328. 8. Brown AFT. Anaphylaxis gets the adrenaline going. Emerg Med J. 2004;21:128–129. 9. Ishoo E, Shah UK, Grillone GA, Stram JR, Fuleiham NS. Predicting airway risk in angioedema: staging system based on presentation. Otolaryngol Head Neck Surg. 1999;121:263–268. 10. Simons FE, Gu X, Simons KJ. Epinephrine absorption in adults: intramuscular versus subcutaneous injection. J Allergy Clin Immunol. 2001; 108:871–873. 11. Simons FE, Chan ES, Gu X, Simons KJ. Epinephrine for the out-ofhospital (first-aid) treatment of anaphylaxis in infants: is the ampule/ syringe/needle method practical? J Allergy Clin Immunol. 2001;108: 1040–1044. 12. Brown SG, Blackman KE, Stenlake V, Heddle RJ. Insect sting anaphylaxis; prospective evaluation of treatment with intravenous adrenaline and volume resuscitation. Emerg Med J. 2004;21:149–154. 13. Barach EM, Nowak RM, Lee TG, Tomlanovich MM. Epinephrine for treatment of anaphylactic shock. JAMA. 1984;251:2118–2122. 14. Pumphrey R. Anaphylaxis: can we tell who is at risk of a fatal reaction? Curr Opin Allergy Clin Immunol. 2004;4:285–290. 15. Ellis AK, Day JH. Diagnosis and management of anaphylaxis. CMAJ. 2003;169:307–311. 16. Winbery SL, Lieberman PL. Histamine and antihistamines in anaphylaxis. Clin Allergy Immunol. 2002;17:287–317. 17. Rainbow J, Browne GJ. Fatal asthma or anaphylaxis? Emerg Med J. 2002;19:415–417. 18. Visscher PK, Vetter RS, Camazine S. Removing bee stings. Lancet. 1996;348:301–302. 19. Kill C, Wranze E, Wulf H. Successful treatment of severe anaphylactic shock with vasopressin: two case reports. Int Arch Allergy Immunol. 2004;134:260–261. 20. Williams SR, Denault AY, Pellerin M, Martineau R. Vasopressin for treatment of shock following aprotinin administration. Can J Anaesth. 2004;51:169–172. 21. Yocum MW, Butterfield JH, Klein JS, Volcheck GW, Schroeder DR, Silverstein MD. Epidemiology of anaphylaxis in Olmsted County: a population-based study. J Allergy Clin Immunol. 1999;104(pt 1):452–456. 22. Smith PL, Kagey-Sobotka A, Bleecker ER, Traystman R, Kaplan AP, Gralnick H, Valentine MD, Permutt S, Lichtenstein LM. Physiologic manifestations of human anaphylaxis. J Clin Invest. 1980;66:1072–1080. 23. Stark BJ, Sullivan TJ. Biphasic and protracted anaphylaxis. J Allergy Clin Immunol. 1986;78:76–83. 24. Brazil E, MacNamara AF. ‘Not so immediate‘ hypersensitivity: the danger of biphasic anaphylactic reactions. J Accid Emerg Med. 1998;15: 252–253. 25. Brady WJ Jr, Luber S, Carter CT, Guertter A, Lindbeck G. Multiphasic anaphylaxis: an uncommon event in the emergency department. Acad Emerg Med. 1997;4:193–197. Part 10.6: Anaphylaxis IV-145

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