Effect of Regular Use of High-dose Nebulized β2-Agonists on Resting Energy Expenditure, Weight, and Handgrip Strength in Patients With Chronic Airflow Limitation: Subjects and Study Design

The importance of compliance with the prescribed medication was emphasized at the intervening clinical follow-ups and it was intended that medication would not be changed throughout the study period. If medication was changed in a way that may have affected REE, the patient was excluded from the analysis. A second REE measurement was made after an interval of at least 3 months from the prescription. From our previous experience of “nebulizer assessments” in our unit, we estimated before the study that approximately half of the patients would be taking regular standard-dose salbutamol via an MDI and half would be taking high-dose nebulized (3₂-agonists. The actual dose of p₂-agonists taken regularly was ascertained by direct questioning of the patients at the time of the second REE measurement.
The data from the study of Melchor et al show that eight actuations of salbutamol per day via a correctly used large-volume spacer should give a daily respirable dose of approximately 160 |xg. We have measured the mean “inhaled” aerosol weight through a breathing machine from a sample of 12 nebulizers (Unineb) driven by a compressor (Medix AC 2000) (ie, the equipment our patients used). This was 690 (42) μL from a 4-mL fill volume (J.H. Dennis, personal communication). This suggests a mean total daily inhaled dose of approximately 3,450 μg of salbutamol that was available to patients using the nebulized route. The percentage total dose in respirable particle size (<5-μm diameter) was 55%, and therefore the total lung dose per day, and available for systemic absorption, was approximately 1,900 μg—10 times the amount available by the MDI +spacer route. canadianfamilypharmacy

Measuremen t of REE
REE was measured by open-circuit indirect calorimetry using a monitor (Datex Deltatrac Metabolic Monitor; Datex Instru-mentarium Ltd; Helsinki, Finland). This comprises a plastic canopy that is placed over the head while the subject lies semireclined, relaxed, and still. Room air is drawn into the canopy by a constant-flow rate generator.

Category: Airflow Limitation

Tags: chronic airflow limitation, resting energy expenditure