Asthma

Oxygen

Inhaled beta-agonists

Inhaled anticholinergics

Corticosteroids

Adjunctive medications

Noninvasive ventilation

Intubation as needed

Ventilator management

Manage ABCs
- Oxygen: Patients should be placed on supplemental oxygen therapy as needed to maintain adequate oxygen saturations.
- Patients must be monitored for signs of impending respiratory failure.
Medications (see Table 30.1)
- Inhaled beta-agonists:
  - Inhaled albuterol is the initial rescue medication of choice.
  - Side effects include tremor, nervousness, tachycardia, palpitations, headache, and hyperglycemia.
  - Delivered by nebulizer or metered-dose inhaler (MDI) with spacer device. In severe exacerbations, albuterol should be delivered as a continuous nebulized treatment.
- Inhaled anticholinergics:
  - Ipratropium bromide is an effective adjunctive therapy by addressing airway smooth muscle constriction and airway secretions.
  - Should not be used alone, but has additive effect with inhaled beta-agonists.
- Corticosteroids:
  - Address the inflammatory component of the disease.
  - Administer early in treatment, as they do not take effect for a few hours.
  - There is no difference in treatment effect between enteral (prednisone) and parenteral (methylprednisone) administration; use intravenous/intramuscular route when the patient is unable to take oral medications.
- Subcutaneous epinephrine:
  - An effective adjunct for patients with severe disease or those unable to tolerate inhaled therapy.
  - May produce tachycardia, arrhythmia, vasoconstriction; use with caution in patients with heart disease.
- Subcutaneous terbutaline:
  - Long-acting beta2-agonist.
  - Adjunct for patients with severe disease.
  - May produce tremor or tachycardia.
- Intravenous magnesium sulfate:
  - An adjunctive medication indicated for patients with severe asthma that works by dilating airways and relaxing smooth muscle.
- Heliox:
  - An inhaled mixture of helium and oxygen that is indicated only in severe asthma exacerbations.
  - Works by decreasing the density of any inhaled gas thereby reducing the airflow resistance and work of breathing.
  - A temporary intervention intended to “buy time” while other therapies take effect.
Airway and ventilatory support
- Noninvasive positive-pressure ventilation (NPPV):
  - Constant positive airway pressure (CPAP) and bi-level positive airway pressure (Bi-PAP) may be considered for patients with severe asthma.
  - NPPV works by decreasing the work of breathing but requires a patient with a patent airway and who will be compliant with the therapy.
  - Patients receiving noninvasive positive-pressure ventilation must be carefully monitored for signs of decompensation including altered mental status, hemodynamic instability, hypercarbia, vomiting, and increased dyspnea.
  - If noninvasive methods fail, the patient will require intubation
- Intubation:
  - Patients with altered mental status, severe acidosis, or hemodynamic instability should not be given a trial of NPPV but should be immediately intubated.
  - Lidocaine pretreatment blunts the bronchospastic response from airway manipulation.
  - Consider ketamine for induction, as this may improve bronchodilation.
- Ventilator management:
  - The goal of ventilator management in the asthmatic is to oxygenate and ventilate without worsening hyperinflation, which causes barotrauma and hemodynamic instability.
  - Often requires low tidal volumes, low respiratory rates, long expiratory times, and high inspiratory flow rates.
  - Permissive hypercapnia may be required.
  - Aggressive pharmacological therapy should continue once the patient is intubated.