Why do some patients with wheezing have a reduction in their oxygen saturation after bronchodilator treatment when they otherwise appear to be improving?
Albuterol and other bronchodilators are β-adrenergic agents that are somewhat β 2 selective. β 2 -Receptor stimulation causes vaso dilation as well as broncho dilation. One explanation for decreases in oxygen saturation after treatment with bronchodilators is that pulmonary vasodilation results in increased perfusion of poorly ventilated areas of the lung and worsening of ventilation-perfusion matching. This is seen in a minority of patients; is usually a transient phenomenon; and is not a contraindication to continued, aggressive bronchodilator therapy in children with severe lower airway disease.