Asthma exacerbation resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Abdurahman Khalil, M.D. [2]

Definition

Asthma exacerbations are acute or subacute episodes of progressively worsening symptoms inclusive of one or more of the following: dyspnea, cough, wheezing, and chest tightness, with a measurable decrease in peak expiratory airflow.

Causes

Common Causes

• Viral infections

• Exposure to allergen

• Bacterial infections
• Environmental pollutants

• Occupational irritants and sensitizers
• Medications:aspirin

Diagnosis

Characterize the symptoms:

Examine the patient: Order labs: ❑ O2 saturation (pulse oximetry) ❑ Spirometry ❑ Arterial blood gas (ABG) (PaO2/PCO2 )

Consider alternative diagnosis: ❑ COPD exacerbation ❑ Aspiration pneumonia ❑ Allergy/Hay fever ❑ Vocal cord dysfunction ❑ Foreign body

Classify the severity

Mild: Symptoms: ❑ Breathlessness while walking ❑ Speaks full sentences Signs: ❑ Tachypnea ❑ End expiratory wheezing ❑ Pulse < 100/min ❑ FEV1 ≥ 70% ❑ Pulse oximetry > 95 % ❑ ABG Normal

Moderate: Symptoms: ❑ Breathlessness at rest, prefers sitting ❑ Speaks phrases ❑ Usually agitated Signs: ❑ Tachypnea ❑ Using accessory muscles of respiration ❑ Expiratory wheezing ❑ Pulse 100-120/min ❑ Pulsus paradoxus may be present ❑ FEV1 40-69 % ❑ Pulse oximetry 90-95 % ❑ ABG: PaO2 ≥ 60 mm Hg PCO2 < 42 mm Hg

Severe: Symptoms: ❑ Breathlessness at rest, sits upright ❑ Speaks words ❑ Usually agitated Signs: ❑ Tachypnea ≥ 30/min ❑ Using accessory muscles of respiration ❑ Wheezing throughout inhalation and exhalation ❑ Pulse > 120/min ❑ Pulsus paradoxus present ❑ FEV1 < 40 % ❑ Pulse oximetry < 90 % ❑ ABG: PaO2 < 60 mm Hg PCO2 ≥ 42 mm Hg

Imminent respiratory arrest: Symptoms: ❑ Drowsy or confused Signs: ❑ Paradoxical thoracoabdominal movement ❑ Wheeze absent ❑ Bradycardia ❑ Pulsus paradoxus absent due to resp. fatigue ❑ FEV1 < 25 %

Management

Mild or moderate exacerbation FEV1/PEF ≥ 40-60%

Severe exacerbation FEV1/PEF ≤ 40%

Imminent respiratory arrest

❑ Oxygenate, target SaO2 ≥ 90% ❑ Inhaled SABA by nebulizer or MDI, 3 doses in 1st hour max. ❑ Oral corticosteroid if no response or recent intake of oral steroid

❑ Oxygenate, target SaO2 ≥ 90% ❑ High dose inhaled SABA/MDI plus ipratropium every 20 mins for 1 hour ❑ oral corticosteroids

❑ Intubate and mechanically ventilate with 100% O2 ❑ Nebulized SABA and ipratropium ❑ IV corticosteroids ❑ Consider adjunct therapies

Reassess

Moderate exacerbation: ❑ Inhaled SABA every 60mins ❑ Oral corticosteroid ❑ Treat for 1-3 hours if improvement, admission decision at hours

Severe exacerbation: ❑ Oxygen ❑ Nebulized SABA + Ipratropium continuous ❑ Oral corticosteroids ❑ consider adjunct therapy

Good response: ❑ FEV1/PEF > 70% ❑ No distress ❑ Stable after 60 mins of treatment ❑ Normal physical exam

Incomplete response: ❑ FEV1/PEF 40-69% ❑ Mild-moderate symptoms

Poor response ❑ FEV1/PEF < 40% ❑ PCO2 ≥ 42 mm Hg ❑ Confusion and severe symptoms

Admit to ward: ❑ Oxygen ❑ Inhaled SABA ❑ Oral or IV corticosteroids ❑ Monitor

Admit to ICU: ❑ Oxygen ❑ Inhaled SABA horly or continously Consider adjunct therapies ❑ Possible intubation and mechanical ventilation

Improvement

Discharge ❑ Continue treatment with inhaled SABA ❑ Continue course of oral steroids ❑ Continue/initiate inhaled corticosteroids ❑ Educate patient ❑ Schedule follow up

Shown below is a table summarizing the dosage of drugs used to manage asthma exacerbation:

Drug	Adult dosage
Inhaled Short Acting β Agonists (SABA)
Albuterol/Bitolterol/Pirbuterol a) Nebulizer solution b) MDI	♦ 2.5-5 mg every 20 minutes for 3 doses, then 2.5-10 mg every 1-4 hours as needed or 10-15 mg/hour continuously. ♦ 4-8 puffs every 20 mins upto 4 hours, then every 1-4 hours as needed.
Levalbuterol a) Nebulizer solution b) MDI	♦ 1.25-2.5 mg every 20 mins for 3 doses, then 1.25-5 mg every 1-4 hours as needed. ♦ 4-8 puffs every 20 mins upto 4 hours, then every 1-4 hours as needed.
Anticholinergics
Ipratropium bromide a) Nebulizer solution b) MDI	♦ 0.5 mg every 20 mins for 3 doses, then as needed. ♦ 8 puffs every 20 mins as needed for upto 3 hours.
Ipratropium with albuterol a) Nebulizer solution (each 3 ml containing 0.5 mg ipratropium and 2.5 mg albuterol) b) MDI (each puff contains 18 mcg ipratropium and 90 mcg albuterol)	♦ 3 ml every 20 mins for 3 doses, then as needed. ♦ 8 puffs every 20 mins as needed for 3 hours
Systemic corticosteroids
Prednisone/Prednisolone/Methylprednisolone	♦ 40-80 mg/day in 1 or 2 divided doses until peak expiratory flowrate (PEF) reaches 70% of personal best.

• SABA:short acting beta agonist
• FEV1:forced expiratory volume for the for the first second
• PEF: Expiratory peak flow

Do's

• In severe exacerbation unresponsive to initial management, consider using IV Mg sulfate

Don'ts

• In the initial management of severe exacerbations FEV₁ and PEF are not included, and the treatment should begin on clinical grounds.
• Not recommended medications during hospitalization or emergency care settings
• Methylxanthine
• Antibiotics(except for comorbid conditions)
• Excessive hydration
• Mucolytics
• Chest physical therapy
• Sedation