2. Definition
Asthma is a chronic inflammatory
disorder of the airways in which many
cells and cellular elements play a role.
◦ This inflammation causes recurrent
episodes of
wheezing, breathlessness, chest
tightness, and coughing, particularly at
night or in the early morning.
◦ Associated with widespread but variable
airflow obstruction that is often reversible
either spontaneously or withProgram, EPR3:
National Asthma Education and Prevention treatment.
Guidelines for the
3. Definition
Status asthmaticus
◦ severe bronchospasm that does not
respond to aggressive therapies within 30
to 60 minutes.
Near-fatal
◦ respiratory arrest or evidence of
respiratory failure (Paco2 > 50 mm Hg).
4. Definition
National Asthma Education and Prevention Program, EPR3:
Guidelines for the
5. Severe/Refractory asthma
American Thoracic Society workshop consensus for definition of severe/refractory
asthma (requires one or both major and two minor criteria and that other conditions
have been excluded, exacerbating factors have been treated, and patient is generally
compliant).
6. Pathophysiology
Hallmark reduction in airway diameter
caused by
◦ smooth muscle contraction
◦ vascular congestion
◦ bronchial wall edema
◦ thick secretions
Bronchoconstriction occurs due to
◦ 1. allergic mediators and metabolic
products from inflammatory cells
◦ 2. nonallergic exercise, aspirin-
induced, and menstrual-related asthma
8. Pathophysiology
National Asthma Education and Prevention Program, EPR3:
Guidelines for the
9. Pathophysiology
Early asthmatic response
◦ Release of preformed histamine from
mast cell granules bronchial smooth
muscle and airway edema wheezing
and airflow obstruction (resolves within an
hour )
Late asthmatic response
◦ cytokines generated and released by
mast cells and other local and recruited
inflammatory cells prolonged airflow
obstruction and bronchospasm
10. Pathophysiology
Eosinophils are major effector cells in
asthma
Airway epithelial cells : produced Nitric
oxide (NO) potent vasodilator and may
reflect the presence of inflammation in
asthma
Airway remodeling : Inflammation, mucus
hypersecretion , subepithelial fibrosis
airway smooth muscle
hypertrophy, angiogenesischronic
irreversible airflow limitation
11.
12. Aspirin-exacerbated
respiratory disease (AERD)
Triad
◦ aspirin sensitivity, asthma, and nasal polyps
NSAIDs also precipitate AERD (but not
reported after administration of COX-2 inhibitors )
common precipitant of life-threatening
asthma
Symptoms
◦ occur within 3 hoursprofuse
rhinorrhea, conjunctival injection, periorbital
edema, and occasionally a scarlet flushing of
the head and neck
Definitive diagnosis : provocation
challenges
14. Exercise-induced asthma (EIA)
Etiology is unclear
Atopy is strongly associated with
EIA, and up to 40% of patients with
allergic rhinitis have EIA
Symptom
◦ occur 3-8 min of exercise, peak 8-15 min
after exercise, spontaneous recovery
occurs within 60 min
Prophylaxis : warm-up and a short-
acting inhaled beta2-agonist
15. Menstruation-associated
asthma
Perimenstrual reductions in PEFR of
35 to 80%
Estradiol inhibits eosinophil
degranulation and suppresses LT
activity.
Progesterone have bronchodilator and
anti-inflammatory activity.
Tx : LT
antagonists, LABA , estradiol, progest
erone, and gonadotropin-releasing
16. 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 therapy
Picado C. Classification of severe asthma exacerbations: a proposal. Eur Respir J
17. CLINICAL FEATURES
Symptom : Triad
◦ dyspnea, wheezing, and cough
Early chest constriction and cough
Exacerbation progresses
wheezing, prolonged expiration and
accessory muscle used(indicates
diaphragmatic fatigue)
Tachypnea and tachycardia >120
beats/min are associated with severe
obstruction, but a lower rate does not
R/O severe asthma.
The "silent chest" reflects very severe
18. CLINICAL FEATURES
bronchiolar smooth muscle tone
airway resistance, pulponary
infiltration, V/Q missmatch
Dynamic hyperinflation auto-PEEP
pulsus paradoxus, diastolic LV dysfn
Acute hypercapnia+ intrathoracic
pressure ICP
Signs of impending respiratory failure (1)
◦ inability to speak, altered mental
status, intercostal retraction, worsening
fatigue, and a PCO2 of ≥42 mmHg
(1) National Asthma Education and Prevention Program, EPR3:
Guidelines for the
23. DIAGNOSTIC STRATEGIES
Pulmonary Function Studies
◦ FEV1 or PEFR
◦ the best of 3 consecutive values should be
recorded
Arterial Blood Gas (mild to moderate hypoxemia
with resp. alkalosis)
◦ 1. predicted PFTs of < 30%
◦ 2. clinical course is perplexing Indication
◦ 3. capnography is not available.
◦ acute ventilatory failure hypoventilation
with CO2 retention and resp. acidosis
24. DIAGNOSTIC STRATEGIES
CXR suspected…
◦ pneumonia, pneumothorax, ateltctasis, pn
eumomediastinum, or CHF
ECG should not be routinely
obtained, 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
25. Assessment Summary
The severity of airflow obstruction
cannot be accurately judged by
patients’ symptoms, PE , and
laboratory tests. Serial measurements
of airflow obstruction (FEV1 or PEFR)
are key components of disease
assessment and response to therapy .
33. Medication
The goal of treatment of acute asthma in
the ED is to reverse airflow obstruction
rapidly by repetitive or continuous
administration of inhaled B 2-
agonists, ensure adequate oxygenation, and
relieve inflammation
35. β2-Adrenergic Agonists
Relaxation of bronchial smooth
muscle, inhibit mediator release and
promote mucociliary clearance.
Most common side effect: skeletal
muscle tremor.
◦ others:
nervousness, anxiety, insom
nia, headache,
hyperglycemia, palpitations,
tachycardia, and hypertension.
36. β2-Adrenergic Agonists
SABA (Solution=MDI)
◦ First line drug
◦ Nebulization = MDI + spacer (prefer
nebulization)
◦ Salbutamol 2.5 – 5 * 3 time/hr
◦ MDI with spacer 4– 8 puffs q 20 min up to
4 h, then q 1–4 h as needed.
37. β2-Adrenergic Agonists
IV form (not recommened in USA)
◦ severe nonresponsive acute asthma.
◦ albuterol loading dose 4 μg/kg for 2-5 min
then infusion of 0.1 to 0.2 μg/kg/min
◦ Epinephrine IV titrated to effect (average 1.5
μg/min with a range of 0.5–13.3 μg/min)
SC form
◦ may be used in pt who cannot adequately
inhale albuterol or who experience severe
bronchospasm.
◦ Epinephrine (1:1000 ) 0.2-0.5 mL q 20 -30
min
◦ Terbutaline 0.25 mg SC q 20 min * 3 dose
38. Corticosteroids
Action in the airways
◦ inhibition of recruitment of inflammatory cells
and inhibition of release of proinflammatory
mediators and cytokines from activated
inflammatory and epithelial cells, activate
cytoplasmic glucocorticoid receptors to
regulate directly or indirectly the transcription
of certain target genes resulting in the
synthesis of new proteins.
Two forms
◦ 1. Systemic
◦ 2. Inhaled
39. Corticosteroids
1. Systemic (IV and oral)
◦ speeds the resolution of airflow
obstruction, reduces the rate of relapse and
may decrease admissions in severe, but
not in mild to moderate attacks.
◦ Prednisone 40-60 mg oral loading
◦ Methylprednisolone 40–80 mg/day in one
dose or two divided doses
◦ Demethasone 5 mg
◦ given q 6 hr until PEFR reaches 70% of
predicted value or a personal best value
40. Corticosteroids
IV = oral
Side effects
◦ short-term (hours or days) reversible
increases in glucose (important in
diabetics) and decreases in
potassium, fluid retention with wt
gain, mood alterations including rare
psychosis, hypertension, peptic
ulcers, aseptic necrosis of the femur
41. Corticosteroids
2. Inhaled
ICS + SABA NB: reducing airway reactivity and
edema more effectively
reduce rates of hospitalization
Side effect : Dysphonia, Reflex cough and
bronchospasm, Oral candidiasis
Discharged
Prednisone 40-60 mg oral for 7 day
ICS high-dose budesonide (400 μg, two puffs
twice per day)
43. Anticholinergic Agents
Block smooth muscle constrictor and
secretory consequences of the
PNS, blocking reflex bronchoconstriction
and reversing acute airway obstruction.
affect large, central airways, but
adrenergic drugs dilate smaller airways.
Side effect
◦ dry mouth, thirst, and difficulty swallowing. Less
commonly, tachycardia, restlessness, irritability,
confusion, difficulty in micturition, ileus, blurring
of vision, or an increase in IOP
44. Anticholinergic Agents
Inhaled-ipratropium bromide
◦ Nebulizer solution (0.25 mg/ml) 0.5 mg q 20
min for 1 hr (three doses), then as needed;
◦ MDI (18 μg/puff) 8 puffs q 20 min as
needed, for up to 3 hr
◦ not recommended as monotherapy in ED
slow onset of action
◦ added to SABA for a greater and longer-
lasting bronchodilator effect, reduce rates of
hospitalization by approximately 25% in
severe asthma
Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august
45. Magnesium Sulfate
relaxes bronchial smooth muscle and
dilates asthmatic airways.
I/C (recommended IV > NB)
◦ severe asthma attacks (FEV1 < 25%
predicted) improves airflow obstruction and
decreases the need for hospital admission
◦ MgSO4 2 -3 g IV over 20 min or at rates of
up to 1 g/min to patients with severe
refractory asthma
Side effect
◦ warmth, flushing, sweating, N/V, muscle
weakness and loss of DTR, hypotension, and
respiratory depression.
46. Treatments That Are Not
Recommended
1. Methylxanthines
◦ lack of demonstrated efficacy and increases
in adverse events
2. Antibiotics
◦ should be reserved for pt with bacterial
infection (e.g., pneumonia or sinusitis)
seems likely.
3. Aggressive hydration
4. Mucolytic agents
◦ worsen cough or airflow obstruction
5. Sedation
Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august
47. Leukotriene Modifiers
non-beta-mediated bronchodilating
effects
Zafirlukast (20 mg twice a day)
Montelukast (10 mg daily)
Currently, there is no indication for the
48. Pregnancy
The principles of managing acute asthma in
pregnancy and during lactation are similar
to those for the nonpregnant state.
Early intervention during acute
exacerbation is key to the prevention of
impaired maternal and fetal oxygenation.
PaO2 <70 mm Hg severe hypoxemia
PaCO2 >35 mm Hg respiratory failure
B2-agonist and ICS : safe during pregnancy
and are recommended as a routine part of
asthma management
49. NPPV
BiPAP
◦ well tolerated by children , decrease the
need for intubation and mechanical
ventilation.
◦ Consider for pt. who decline intubation
and pt. who cooperate with mask therapy
◦ but more data are needed to recommend
this approach
Patient must be alert mental status
and intact airway reflexes
Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august
50. Ketamine
potent bronchodilator effects
no randomized trials have been
conducted.
not recommended for therapy of acute
asthma in the nonintubated patient
Ketamine 1–2 mg/kg IV
Side effect
◦ increased airway secretions and
emergence reactions
51. Intubation and Ventilator
Strategy
Avoid nasotracheal route
Intubate before the crisis of respiratory
arrest
Selected largest ET-tube as soon as
possible.
Pretreatment
◦ Lidocaine 1.5 mg/kg IV
Induction
◦ Midazolam 1 mg IV q 2-3 min
◦ Ketamine 1–2 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:
52. Intubation and Ventilator
Strategy
Ventilator strategy
◦ adequate oxygenation and
ventilation, minimizing high airway
pressure, barotrauma, and systemic
hypotension
Permissive hypercapnia technique
◦ TV 6–8 mL/kg, MV 6-8 LPM
◦ I:E > 1:3, RR 11-14 /min
◦ End-inspiratory pressure < 35 cmH2O
◦ pH maintained at 7.15–7.2
◦ Paco2 <100 mm Hg
53. Intubation and Ventilator
Strategy
Complications of mechanical
ventilation
◦ Hypotension and barotrauma
◦ Pneumothorax !!!
sudden clinical deterioration
hypotension
significant rise in peak inspiratory ventilator
pressures and falling oxygen saturation.
External lateral chest compression :
patients cannot exhale esp; children
54. Cardiopulmonary arrest
May result from unrecognized
barotrauma.
◦ Empirical bilateral tube thoracostomy
should be performed if unexplained
cardiac arrest occurs, especially in the
context of dramatic increases in peak
inspiratory pressure.
◦ IV epinephrine has both cardiostimulatory
and bronchodilatory properties.
55. DISPOSITION
When should be discharged
◦ FEV or PEF after treatment is >= of the
11
personal best or predicted value
◦ Improvements in lung function and
symptoms > 60 min
Emergency Treatment of Asthma, N ENGL J MED 363;8 nejm.org august