The efficacy of bronchodilator drugs administered by metered-dose inhalers depends on adherence to proper technique. Alternate devices for delivery, including spacers and ultrasonic and air-compressor nebulizers, have been proposed for use in ambulatory patients. These devices are being prescribed for patients who either have difficulty in using a metered-dose inhaler or have inadequate control by standard therapy, including bronchodilators administered by metered-dose inhaler.
In this study, we compared the bronchodilator response to albuterol (salbutamol) delivered by metered-dose inhaler and ultrasonic nebulizer in subjects with moderately severe stable obstructive pulmonary disease.
Materials and Methods
Nineteen outpatients (13 male and six female subjects; mean age, 61 years) with stable obstructive pulmonary disease were studied. Six were asthmatic, and 13 had chronic obstructive pulmonary disease (COPD) (criteria of American Thoracic Society). Twelve were taking theophylline, nine ipratropium, eight inhaled steroids, and seven oral steroids. All subjects had been taking oral or inhaled P-adrenergic agonists. The baseline value for forced vital capacity (FVC) was 1.58 + 0.11 L (± SE), for forced expiratory volume in one second (FEV,) was LOO + 0.10 L (45 percent of predicted), and for the mean forced expiratory flow over the middle half of the FVC (FEF25-75%) was 0.62 -I- 0.10 L/sec. No subject had previously used an ultrasonic or air-compressor nebulizer. Subjects abstained from bronchodilator therapy for eight hours prior to study. Oral steroids were administered as usual. Informed consent was obtained from each patient.
The two regimens tested were 200 μg of albuterol (Ventolin – visit http://buy-asthma-inhalers-online.com/ventolin-inhaler-100mcg-salbutamol.html) in two puffs by metered-dose inhaler and 2.5 mg of albuterol in 1.5 ml of isotonic saline solution by ultrasonic nebulizer (Bosch Halomed model S). The nebulizers output was 1.4 ± 0.3 ml/min (± SD) when 5 ml of solution was nebulized by continuous flow for two minutes. The mass median diameter was 7.5 μ. Using tidal breathing, the patients inhaled the solution nebulized during inspiration via a face mask.
On the first day, spirometric testing was done in triplicate from a recording spirometer (Vitalograph model S). The FVC, FEVt, and FEF25-75% were measured from the best spirogram (sum of FEV, plus FVC). The subjects then inhaled albuterol from a metered-dose inhaler using the closed-mouth technique with a ten-second breath-hold. Spirometry was repeated 30 minutes later.
All subjects then underwent a two-week trial at home with the ultrasonic nebulizer administering albuterol four times daily. On day 14, spirometry was repeated before and after inhalation of albuterol by nebulizer. Patients evaluated the 14-day trial of the ultrasonic nebulizer by comparing it with their previous experience with the metered-dose inhaler.
Subjects with an increase in FEV1 of 15 percent or more 30 minutes after albuterol delivered by either metered-dose inhaler or ultrasonic nebulizer were considered to be responders. Subjects were classified as responders to metered-dose inhaler, as responders to ultrasonic nebulizer, or as nonresponders.
Eleven subjects who volunteered to undergo further testing (eight male and three female subjects) were reevaluated to determine the placebo effect of aerosol by metered-dose inhaler and ultrasonic nebulizer. A Freon propellant (two puffs) or isotonic saline solution (2.0 ml) was administered in a randomized crossover single-blind fashion on two separate days at the same time of day. Data obtained after placebo were compared to those obtained previously in these 11 subjects before and after administration of albuterol.
The paired f-test was used to evaluate the significance of differences between observations.