RESUMO
The Spacehaler is a new, compact, pressurized aerosol device that uses the same canister as a conventional metered-dose inhaler (MDI). Its design, however, reduces the velocity of the aerosol cloud that emerges from the inhaler, thereby reducing the amount of the non-respirable fraction of the drug delivered to the patient. Large volume spacers achieve a similar effect, but they are bulky and therefore inconvenient to use and carry around. This study compared the bronchodilator effect of 200 micrograms salbutamol delivered by the Spacehaler to that of an MDI used with a Volumatic spacer (MDI plus spacer) in patients with reversible obstructive airways disease. Twenty-five patients with asthma, having a forced expiratory volume in 1 s (FEV1) between 50 and 90% predicted and a reversibility of > or = 15% to 200 micrograms salbutamol given by the conventional (standard) MDI entered the study. On two separate study days, they inhaled 200 micrograms salbutamol either via the Spacehaler or the MDI plus spacer. To maintain blinding, they received placebo on both study days via the alternate device. Their FEV1, forced vital capacity (FVC) and peak expiratory flow (PEF) were measured before and at regular intervals for 6 h after inhalation. Assessment of equivalence between the two devices was based on whether the 90% confidence interval for the difference between the weighted mean FEV1 was within +/- 0.25 1. Patient preference was assessed by a questionnaire at the end of the second study day. Twenty-four patients completed the study. Both devices produced a significant improvement in FEV1 (P < 0.02). The upper and lower 90% confidence limits for the difference in weighted mean FEV1 between the devices was +/- 0.041, and the 99% confidence limits were +0.061 and -0.071. The weighted means for FVC and PEF, and the duration of effect and peak responses for FEV1, FVC and PEF also showed no difference between the two devices. Patients found no difficulty in using the Spacehaler, and 20 out of 24 patients (83.3%) preferred it to the MDI plus spacer. The bronchodilator effect of 200 micrograms salbutamol administered by a Spacehaler was equivalent to that produced by an MDI plus spacer in this group of patients with reversible airways obstruction. The majority of patients preferred it to a large volume spacer.
