Does 100% Oxygen Adversely Affect Severe Asthma Exacerbation?

It is an accepted tenet in the management of severe asthma that supplemental 100% oxygen should be provided. Concerns about "oxygen toxicity" in COPD patients traditionally have not been considered in the care of asthmatics. These authors challenged that approach in a prospective study of 37 adults with asthma exacerbations.

Patients received 100% oxygen by nonrebreather face mask for 20 minutes; arterial blood gases and FEV₁ were measured during the first and last minute of therapy. No bronchodilators were administered during oxygen therapy. Initially, the study group suffered moderately severe airway obstruction (FEV₁, 49(plusoverminus)3.6% of predicted) and mild hypocarbia (PaCO₂, 36.8(plusoverminus)1.1 mm Hg). During oxygen administratio…