In patients with acute chronic obstructive pulmonary disease (COPD) exacerbations, the use of air-driven nebulizers avoids the potential risk of increasing the arterial partial pressure of carbon dioxide associated with the use of oxygen-driven bronchodilator administration, according to the results of a clinical trial conducted at Wellington Regional Hospital in New Zealand and published in BMC Pulmonary Medicine.
Investigators sought to compare the effects of air-driven vs oxygen-driven bronchodilator nebulization on arterial carbon dioxide tension in 90 patients with acute COPD exacerbations. All participants randomly received 2 salbutamol 2.5-mg nebulizations, both driven by either air (n=44) or oxygen (n=45) at 8 L/min. Each nebulization was delivered over the course of 15 minutes, with a 5-minute interval between the 2 nebulizations.
The primary study outcome was the transcutaneous partial pressure of carbon dioxide (PtCO2) at the end of the second nebulization (ie, 35 minutes). The analysis was performed by intention to treat.
In 1 of the participants who received oxygen-driven nebulization, the treatment was terminated after 27 minutes because the PtCO2 rose by >10 mm Hg, which is a prespecified safety end point. The mean change in PtCO2 after 35 minutes was 3.4±1.9 mm Hg and 0.1±1.4 mm Hg in the oxygen-driven vs air-driven groups, respectively, representing a significant difference of 3.3 mm Hg (95% CI, 2.7-3.9; P <.001). The proportion of participants with a PtCO2 change of ≥4 mm Hg from baseline during the intervention was 40% (18 of 45) of those in the oxygen-driven group vs 0% (0 of 44) of those in the air-driven group (95% CI, 25.7-54.3; P <.001).
The investigators concluded that air-driven bronchodilator nebulization is preferable to oxygen-driven nebulization in patients experiencing acute COPD exacerbations. A major issue associated with the use of oxygen-driven bronchodilation is the potential for rebound hypoxia after the abrupt end of therapy. They recommended that when the use of oxygen-driven nebulization is unavoidable, PtCO2 should be monitored if possible.
Bardsley G, Pilcher J, McKinstry S, et al. Oxygen versus air-driven nebulisers for exacerbations of chronic obstructive pulmonary disease: a randomised controlled trial. BMC Pulm Med. 2018;18(1):157.