Asthma, Adult

Asthma, Adult

Description

• Increased expiratory resistance:




• Bronchospasm


• Airway inflammation


• Mucosal edema


• Mucous plugging




• Consequences:




• Air trapping


• Increased dead space


• Hyperinflation




• Risk factors for life-threatening disease:




• Prior intubations


• Intensive care unit admissions


• Chronic steroid use


• Hospital admission for asthma during the past year


• Inadequate medical management


• Increasing age


• Ethnicity (African Americans)


• Lack of access to medical care

Etiology

Mechanism

• Pollen


• Dust mites


• Molds


• Animal dander


• Other environmental allergens


• Viral upper respiratory infections


• Occupational chemicals


• Tobacco smoke


• Environmental change


• Cold air


• Exercise


• Emotional factors


• Drugs:




• Aspirin


• NSAIDs


• Beta-blockers

Diagnosis

Signs and Symptoms

• Wheezing


• Dyspnea


• Chest tightness


• Cough


• Tachypnea


• Tachycardia


• Respiratory distress:




• Posture sitting upright or leaning forward


• Use of accessory muscles


• Inability to speak in full sentences


• Diaphoresis


• Poor air movement




• Altered mental status

Essential Workup

• Primarily a clinical diagnosis


• Measure and follow severity with peak expiratory flow rate (PEFR)


• Assess for underlying disease


• Pneumonia:




• Pneumothorax

Tests

Lab

• Arterial blood gas:




• Not helpful during the initial evaluation


• The decision to intubate should be based on clinical criteria.


• Mild-moderate asthma: respiratory alkalosis


• Severe airflow obstruction and fatigue: respiratory acidosis




• Pulse oximetry:




• Less than 90% is indicative of severe respiratory distress


• Patients with impending respiratory compromise may still maintain saturation above 90% until sudden collapse.




• WBC:




• Leukocytosis is nonspecific


• Pneumonia


• Chronic steroid use


• Stress of an asthma exacerbation


• Demargination occurs after administration of epinephrine and steroids.

Imaging

• Peak expiratory flow rate:




• Estimates the degree of airflow obstruction:




• Normal peak flow in an adult is 400–600


• Between 100 and 300 indicates moderate airway obstruction.




• Use serially as an objective measure of the response to therapy






• Forced expiratory volume (FEV):




• More reliable measure of lung function than PEFR


• More operator dependent


• Difficult to use as a screening tool


• Often unavailable in the ED


• Severe airway obstruction: FEV₁ less than 30–50%




• Chest radiograph:




• Indications:




• Fever


• Suspicion of pneumonia


• Suspicion of pneumothorax or pneumomediastinum


• Foreign body aspiration


• First episode of asthma


• Comorbid illness


• Diabetes


• Renal failure


• AIDS


• Cancer




• Findings:




• Hyperinflation


• Scattered atelectasis






• ECG:




• Indicated in patients at risk for cardiac disease:




• Dysrhythmias


• Myocardial ischemia




• Transient changes in severe asthma:




• Right axis deviation


• Right bundle branch block


• Abnormal P waves


• Nonspecific ST-T wave changes

Differential Diagnosis

• Congestive heart failure


• Myocardial ischemia


• Pulmonary embolus


• Pneumonia


• Bronchitis


• Bronchiolitis


• Croup


• Foreign body aspiration


• Upper airway obstruction


• Angioedema


• Allergic reaction


• Chronic obstructive pulmonary disease


• Chronic cor pulmonale


• Chemical pneumonitis


• Carcinoid tumors


• Smoke inhalation


• Immersion injury


• Venous air embolus

Treatment

Pre Hospital

• Recognize the ‘quiet chest’ as respiratory distress.


• Supplemental oxygen


• Continuous nebulized β2-agonist


• Administration of subcutaneous epinephrine


• Severe disease with decreased breath sounds

Initial Stabilization

• Immediate initiation of inhaled β2-agonist treatment


• Intubate for fatigue and respiratory distress.


• Steroids

ED Treatment

β2Adrenergic Agonist

• Mild-moderate asthmatic:




• Administer every 20 minutes




• Severe asthmatic:




• Continuous nebulized treatment




• Selective β2-agonists (albuterol)


• Subcutaneous β-agonist:




• Severe exacerbations


• Limited inhalation of aerosolized medicine


• More side effects because of systemic absorption:




• Tachycardia


• Tremors




• Relative contraindications: age >40 years and coronary disease




• 
  Corticosteroids:
  




• Reduce airway wall inflammation


• Administered early


• Onset of action may take 4-6 hours


• Administer intravenously or orally


• IV Solu-Medrol in the treatment of severe asthma exacerbation


• Mild-moderate exacerbations may be treated with oral prednisone.


• Inhaled corticosteroids are currently not recommended as initial therapy.




• Oxygen:




• Maintain an oxygen saturation above 90%




• Aminophylline:




• Rare utility in acute management


• Toxicity:




• Nausea


• Tremor


• Anxiety


• Palpitations


• Tachycardia






• Anticholinergic agents:




• If minimal response to initial β2-agonist treatment


• Severe airflow obstruction


• Inhaled anticholinergic agents should be used in conjunction with β2-agonists.




• Magnesium sulfate:




• No benefit in mild-moderate asthma


• Benefit of magnesium remains unclear in severe asthma




• Heliox:




• Mixture of helium and oxygen (80:20, 70:30, 60:40)


• Less dense than air


• Decrease airway resistance.


• Decrease in respiratory exhaustion


• Not currently recommended for routine use:




• Consider in severe asthma






• Ketamine:




• Bronchodilator and an anesthetic agent


• Useful as an induction agent during intubation


• Contraindications:




• Hypertension


• Coronary disease


• Pre-eclampsia


• Increased intracranial pressure






• Halothane:




• Inhalation anesthetics are potent bronchodilators.


• Refractory asthma in intubated patients




• Intubation of the asthmatic patient:




• Rapid sequence intubation:




• Lidocaine to attenuate airway reflexes


• Etomidate or ketamine as an induction agent


• Succinylcholine should be administered to achieve paralysis.


• A large endotracheal tube >7 mm should be used to facilitate ventilation.


• May need to mechanically exhale for the patient


• Permissive hypercapnia

Medication (Drugs)

• β2-agonists




• Albuterol: 2.5 mg in 2.5 mL normal saline q20min inhaled (peds: 0.1-0.15 mg/kg/dose q20min [minimum dose 1.25 mg])


• Epinephrine: adult: 0.3 mg (1:1,000) SC q0.5h-q4.0h × three doses (peds: 0.01 mg/kg up to 0.3 mg SC)


• Terbutaline: 0.25 mg SC q0.5h × two doses (peds: 0.01 mg/kg up to 0.3 mg SC)




• Corticosteroids:




• Methylprednisolone: 60-125 mg IV (peds: 1-2 mg/kg/dose IV or PO q6h × 24 hours)


• Prednisone: 40-60 mg PO (peds: 1-2 mg/kg/day in single or divided doses)




• Anticholinergics




• Ipratropium bromide: 0.5 mg in 3 mL NS q1h × three doses




• Magnesium: 2 g IV over 20 minutes


• Aminophylline: 0.6 mg/kg/h IV infusion


• Rapid sequence intubation:




• Etomidate: 0.3 mg/kg, or ketamine: 1-1.5 mg/kg


• Lidocaine: 1-1.5 mg/kg


• Succinylcholine: 1.5 mg/kg

Follow-Up

Disposition

Admission Criteria

• Persistent respiratory distress


• PEFR


• Intubated patients

Medical Wards or Observation Unit

• PEFR


• Patients without subjective improvement


• Patients with continued wheeze and diminished air movement


• Patients with moderate response to therapy and no respiratory distress:




• Factors that should favor admission


• Prior intubation


• Recent ED visit


• Multiple ED visits or hospitalizations


• Symptoms for more than 1 week


• Failure of outpatient therapy


• Use of steroids


• Inadequate follow-up mechanisms


• Psychiatric illness




• Complications:




• Pneumothorax


• Pneumomediastinum


• Pneumonia


• Fatigue

Discharge Criteria

• Patient reports subjective improvement


• Clear lungs with good air movement


• PEFR or FEV₁ greater than 70% of predicted


• Peak flow should be greater than 300.


• Adequate follow-up within 48–72 hours

References

1. Corbridge TC, Hall JB. The assessment and management of adults with status asthmaticus. Am J Respir Crit Care Med. 1995;151:1296-1316.

2. Guidelines for the diagnosis and management of asthma: National Asthma Education Program Expert Panel Report. Bethesda, MD: Department of Health and Human Services; 1991. NIH 91-3042.

3. Jagoda A, Shepherd SM, Spevitz A, et al. Refractory asthma, part 1: epidemiology, pathophysiology, pharmacologic interventions. Ann Emerg Med. 1997;29:262-274.

4. Jagoda A, Shepherd SM, Spevitz A, et al. Refractory asthma, part 2. Airway interventions and management. Ann Emerg Med. 1997;29:275-281.

5. Manthous CA. Management of severe exacerbations of asthma. Am J Med. 1995;99:298-308.

Codes

ICD9-CM

493

ICD10

J45.9