Acute asthma in adults

• 1. Acute Asthma inAdults Krit Kuruchaiyapanich, MD

2. Definition Asthma is a chronic inflammatorydisorder of the airways in which manycells and cellular elements play a role. This inflammation causes recurrentepisodes ofwheezing, breathlessness, chesttightness, and coughing, particularly atnight or in the early morning. Associated with widespread but variableairflow obstruction that is often reversibleeither spontaneously or withProgram, EPR3:National Asthma Education and Prevention treatment.Guidelines for the 3. Definition Status asthmaticus severe bronchospasm that does notrespond to aggressive therapies within 30to 60 minutes. Near-fatal respiratory arrest or evidence ofrespiratory failure (Paco2 > 50 mm Hg). 4. DefinitionNational Asthma Education and Prevention Program, EPR3:Guidelines for the 5. Severe/Refractory asthmaAmerican Thoracic Society workshop consensus for definition of severe/refractoryasthma (requires one or both major and two minor criteria and that other conditionshave been excluded, exacerbating factors have been treated, and patient is generallycompliant). 6. Pathophysiology Hallmark reduction in airway diametercaused by smooth muscle contraction vascular congestion bronchial wall edema thick secretions Bronchoconstriction occurs due to 1. allergic mediators and metabolicproducts from inflammatory cells 2. nonallergic exercise, aspirin-induced, and menstrual-related asthma 7. Pathophysiology 8. PathophysiologyNational Asthma Education and Prevention Program, EPR3:Guidelines for the 9. Pathophysiology Early asthmatic response Release of preformed histamine frommast cell granules bronchial smoothmuscle and airway edema wheezingand airflow obstruction (resolves within anhour ) Late asthmatic response cytokines generated and released bymast cells and other local and recruitedinflammatory cells prolonged airflowobstruction and bronchospasm 10. Pathophysiology Eosinophils are major effector cells inasthma Airway epithelial cells : produced Nitricoxide (NO) potent vasodilator and mayreflect the presence of inflammation inasthma Airway remodeling : Inflammation, mucushypersecretion , subepithelial fibrosisairway smooth musclehypertrophy, angiogenesischronicirreversible airflow limitation 11. Aspirin-exacerbatedrespiratory disease (AERD) Triad aspirin sensitivity, asthma, and nasal polyps NSAIDs also precipitate AERD (but notreported after administration of COX-2 inhibitors ) common precipitant of life-threateningasthma Symptoms occur within 3 hoursprofuserhinorrhea, conjunctival injection, periorbitaledema, and occasionally a scarlet flushing ofthe head and neck Definitive diagnosis : provocationchallenges 12. Aspirin-exacerbated respiratorydisease (AERD) 13. Exercise-induced asthma (EIA) Etiology is unclear Atopy is strongly associated withEIA, and up to 40% of patients withallergic rhinitis have EIA Symptom occur 3-8 min of exercise, peak 8-15 minafter exercise, spontaneous recoveryoccurs within 60 min Prophylaxis : warm-up and a short-acting inhaled beta2-agonist 14. Menstruation-associatedasthma Perimenstrual reductions in PEFR of35 to 80% Estradiol inhibits eosinophildegranulation and suppresses LTactivity. Progesterone have bronchodilator andanti-inflammatory activity. Tx : LTantagonists, LABA , estradiol, progesterone, and gonadotropin-releasing 15. CLINICAL FEATURES Classification 1. Type 1 (Slow onset> 6 hr) 80-90% Female>male Etiology: URI Inflammation less severity than type 2 slower response to therapy 2. Type 2 (Sudden onset< 6 hr) 10-20% Male>female Etiology: respiratory allergen, exercise, stress Bronchoconstriction more severe faster response to therapyPicado C. Classification of severe asthma exacerbations: a proposal. Eur Respir J 16. CLINICAL FEATURES Symptom : Triad dyspnea, wheezing, and cough Early chest constriction and cough Exacerbation progresseswheezing, prolonged expiration andaccessory muscle used(indicatesdiaphragmatic fatigue) Tachypnea and tachycardia >120beats/min are associated with severeobstruction, but a lower rate does notR/O severe asthma. The "silent chest" reflects very severe 17. CLINICAL FEATURESbronchiolar smooth muscle toneairway resistance, pulponaryinfiltration, V/Q missmatch Dynamic hyperinflation auto-PEEPpulsus paradoxus, diastolic LV dysfn Acute hypercapnia+ intrathoracicpressure ICP Signs of impending respiratory failure (1) inability to speak, altered mentalstatus, intercostal retraction, worseningfatigue, and a PCO2 of 42 mmHg (1) National Asthma Education and Prevention Program, EPR3: Guidelines for the 18. SEVERITY OF ASTHMAEXACERBATIONS National Asthma Education and Prevention Program, EPR3: Guidelines for the 19. Risk factors for death fromasthma 20. DIAGNOSTIC STRATEGIES Pulmonary Function Studies FEV1 or PEFR the best of 3 consecutive values should berecorded Arterial Blood Gas (mild to moderate hypoxemiawith resp. alkalosis) 1. predicted PFTs of < 30% 2. clinical course is perplexing Indication 3. capnography is not available. acute ventilatory failure hypoventilationwith CO2 retention and resp. acidosis 21. DIAGNOSTIC STRATEGIES CXR suspected pneumonia, pneumothorax, ateltctasis, pneumomediastinum, or CHF ECG should not be routinelyobtained, except patients >40 yr, a separate complaint(e.g., chest pain), Hx of significant CVD severe asthma: a RV strain pattern Others LTE4 in the urine exhaled nitric oxide 22. Assessment Summary The severity of airflow obstructioncannot be accurately judged bypatients symptoms, PE , andlaboratory tests. Serial measurementsof airflow obstruction (FEV1 or PEFR)are key components of diseaseassessment and response to therapy . 23. Peak Flow Meter 24. Management Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 25. Management Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 26. Management Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 27. Management Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 28. MedicationThe goal of treatment of acute asthma inthe ED is to reverse airflow obstructionrapidly by repetitive or continuousadministration of inhaled B 2-agonists, ensure adequate oxygenation, andrelieve inflammation 29. Medication1. Relievers- B2-adrenergic , Anticholinergics, Theophyline2. Controller- Glucocorticoids, Leukotrienemodifiers, Cromones, Anti-IgE 30. 2-Adrenergic Agonists Relaxation of bronchial smoothmuscle, inhibit mediator release andpromote mucociliary clearance. Most common side effect: skeletalmuscle tremor. others:nervousness, anxiety,insomnia, headache,hyperglycemia, palpitations,tachycardia, and hypertension. 31. 2-Adrenergic Agonists SABA (Solution=MDI) First line drug Nebulization = MDI + spacer (prefernebulization) Salbutamol 2.5 5 * 3 time/hr MDI with spacer 4 8 puffs q 20 min up to4 h, then q 14 h as needed. 32. 2-Adrenergic Agonists IV form (not recommened in USA) severe nonresponsive acute asthma. albuterol loading dose 4 g/kg for 2-5 minthen infusion of 0.1 to 0.2 g/kg/min Epinephrine IV titrated to effect (average 1.5g/min with a range of 0.513.3 g/min) SC form may be used in pt who cannot adequatelyinhale albuterol or who experience severebronchospasm. Epinephrine (1:1000 ) 0.2-0.5 mL q 20 -30min Terbutaline 0.25 mg SC q 20 min * 3 dose 33. Corticosteroids Action in the airways inhibition of recruitment of inflammatory cellsand inhibition of release of proinflammatorymediators and cytokines from activatedinflammatory and epithelial cells, activatecytoplasmic glucocorticoid receptors toregulate directly or indirectly the transcriptionof certain target genes resulting in thesynthesis of new proteins. Two forms 1. Systemic 2. Inhaled 34. Corticosteroids 1. Systemic (IV and oral) speeds the resolution of airflowobstruction, reduces the rate of relapse andmay decrease admissions in severe, butnot in mild to moderate attacks. Prednisone 40-60 mg oral loading Methylprednisolone 4080 mg/day in onedose or two divided doses Demethasone 5 mg given q 6 hr until PEFR reaches 70% ofpredicted value or a personal best value 35. Corticosteroids IV = oral Side effects short-term (hours or days) reversibleincreases in glucose (important indiabetics) and decreases inpotassium, fluid retention with wtgain, mood alterations including rarepsychosis, hypertension, pepticulcers, aseptic necrosis of the femur 36. Corticosteroids 2. Inhaled ICS + SABA NB: reducing airway reactivity andedema more effectively reduce rates of hospitalization Side effect : Dysphonia, Reflex cough andbronchospasm, Oral candidiasis Discharged Prednisone 40-60 mg oral for 7 day ICS high-dose budesonide (400 g, two puffstwice per day) 37. Anticholinergic AgentsAtropa BelladonnaLeave 38. Anticholinergic Agents Block smooth muscle constrictor andsecretory consequences of thePNS, blocking reflex bronchoconstrictionand reversing acute airway obstruction. affect large, central airways, butadrenergic drugs dilate smaller airways. Side effect dry mouth, thirst, and difficulty swallowing. Lesscommonly, tachycardia, restlessness, irritability,confusion, difficulty in micturition, ileus, blurringof vision, or an increase in IOP 39. Anticholinergic Agents Inhaled-ipratropium bromide Nebulizer solution (0.25 mg/ml) 0.5 mg q 20min for 1 hr (three doses), then as needed; MDI (18 g/puff) 8 puffs q 20 min asneeded, for up to 3 hr not recommended as monotherapy in EDslow onset of action added to SABA for a greater and longer-lasting bronchodilator effect, reduce rates ofhospitalization by approximately 25% insevere asthmaEmergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 40. Magnesium Sulfate relaxes bronchial smooth muscle anddilates asthmatic airways. I/C (recommended IV > NB) severe asthma attacks (FEV1 < 25%predicted) improves airflow obstruction anddecreases the need for hospital admission MgSO4 2 -3 g IV over 20 min or at rates ofup to 1 g/min to patients with severerefractory asthma Side effect warmth, flushing, sweating, N/V, muscleweakness and loss of DTR, hypotension, andrespiratory depression. 41. Treatments That Are NotRecommended 1. Methylxanthines lack of demonstrated efficacy and increasesin adverse events 2. Antibiotics should be reserved for pt with bacterialinfection (e.g., pneumonia or sinusitis)seems likely. 3. Aggressive hydration 4. Mucolytic agents worsen cough or airflow obstruction 5. SedationEmergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 42. Leukotriene Modifiers non-beta-mediated bronchodilatingeffects Zafirlukast (20 mg twice a day) Montelukast (10 mg daily) Currently, there is no indication for the 43. Pregnancy The principles of managing acute asthma inpregnancy and during lactation are similarto those for the nonpregnant state. Early intervention during acuteexacerbation is key to the prevention ofimpaired maternal and fetal oxygenation. PaO2 35 mm Hg respiratory failure B2-agonist and ICS : safe during pregnancyand are recommended as a routine part ofasthma management 44. NPPV BiPAP well tolerated by children , decrease theneed for intubation and mechanicalventilation. Consider for pt. who decline intubationand pt. who cooperate with mask therapy but more data are needed to recommendthis approach Patient must be alert mental statusand intact airway reflexesEmergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 45. Ketamine potent bronchodilator effects no randomized trials have beenconducted. not recommended for therapy of acuteasthma in the nonintubated patient Ketamine 12 mg/kg IV Side effect increased airway secretions andemergence reactions 46. Intubation and VentilatorStrategy Avoid nasotracheal route Intubate before the crisis of respiratoryarrest Selected largest ET-tube as soon aspossible. Pretreatment Lidocaine 1.5 mg/kg IV Induction Midazolam 1 mg IV q 2-3 min Ketamine 12 mg/kg IV Neuromuscular blocking agent Preferred Rocuronium (1 mg/kg) >Rodrigo GJ, Rodrigo C, Hall JB. Acute asthma in adult: a review. Chest 2004; 125: 47. Intubation and VentilatorStrategy Ventilator strategy adequate oxygenation and ventilation, minimizing high airway pressure, barotrauma, and systemic hypotension Permissive hypercapnia technique TV 68 mL/kg, MV 6-8 LPM I:E > 1:3, RR 11-14 /min End-inspiratory pressure < 35 cmH2O pH maintained at 7.157.2 Paco2 = of the11personal best or predicted value Improvements in lung function andsymptoms > 60 minEmergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 51. DISPOSITION Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august 52. THANK YOU