“…In an outpatient study of patients with COPD, Pauwels et al 131 compared the use of an MDI and that of an MDI with a valved holding chamber following the inhalation of terbutaline, and reported that the MDI with holding chamber may be more effective than MDI alone. In an outpatient study of patients with asthma or COPD, Dorow and Hidinger et al 132 reported no differences between the use of an MDI and that of MDI with a valved holding chamber.…”