Pulmonary Disorders II

Oxygen therapy is important in managing acute severe asthma.

hypoxemia to achieve Sao2 values greater than 93%–95% (pregnant women and patients with a cardiac

history may require higher goals) (GINA 2024; Thorax 2011;66:937-41).

High-Flow Nasal Cannula and Noninvasive Ventilation: Data are insufficient for use in severe exacerbations

(Global Initiative for Asthma 2024). Recent data indicate that these modalities are increasingly being

noninvasive ventilation. Further research is needed to define the roles of these modalities in severe asthma

Mechanical Ventilation

Indications

Worsening hypoxemia or hypercarbia

Drowsiness or altered mental status

Hemodynamic instability

and minimal PEEP on the ventilator will help minimize dynamic hyperinflation.

SABAs stimulate the β2-receptors on smooth muscle cells, leading to relaxation of respiratory smooth

muscle and causing bronchodilation and decreased airway obstruction.

Patients with an asthma exacerbation should receive a SABA repeatedly by either an MDI or

nebulization at presentation, and the SABA should be continued until acute symptoms have resolved

(Global Initiative for Asthma 2024).

Patients with acute severe exacerbations may benefit from continuous versus intermittent nebulization

of SABAs, though differences in outcomes between studies are conflicting (Global Initiative for Asthma

2024; Cochrane Database Syst Rev 2003;4:CD001115).

Intermittent dosing of albuterol: 2.5–5 mg every 20 minutes for three doses; then 2.5–10 mg every

1–4 hours as needed

Continuous nebulization of albuterol: 10–15 mg/hour

Systemic β-agonists can be considered if the patient does not respond to inhaled therapy after several

hours (Chest 2022;162:747-56).

These agents have no proven advantage over inhaled agents or over each other and are not

recommended for routine use because of the high rate of adverse effects.

However, if the patient’s acute asthma exacerbation is caused by anaphylaxis or angioedema,

epinephrine would be recommended.

Epinephrine 1 mg/mL 0.3–0.5 mg intramuscularly/subcutaneously every 20 minutes up to three

doses

Terbutaline 0.25 mg subcutaneously every 20 minutes for three doses

Adverse effects include tremor, tachyarrhythmias, hypokalemia, tachyphylaxis, hyperglycemia, and

type B lactic acidosis.