title: Effect of salbutamol on the measurement of single-breath diffusing capacity.
abstract: OBJECTIVE
  The bronchodilation and cardiovascular effects of bronchodilators may alter alveolar ventilation and perfusion distribution, which could subsequently affect single-breath diffusing capacity of the lungs for carbon monoxide (DL ,CO) measurements. The aim of this study was to investigate the effect of salbutamol on DL ,CO in subjects with and without airway obstruction and reversibility.
  
  
  METHODS
  Sixty subjects were investigated with 20 in each of the three groups: normal spirometry; irreversible obstruction; and reversible obstruction. Baseline spirometry, plethysmographic lung volumes, DL ,CO, pulse rate and arterial blood gases were measured. The same testing sequence was repeated after administration of a placebo inhaler and again after 400 μg salbutamol.
  
  
  RESULTS
  Salbutamol did not affect the mean alveolar volume (VA ) (P > 0.05), transfer coefficient for carbon monoxide (DL ,CO/VA , KCO) (P > 0.05) or DL ,CO (P > 0.05) in the normal and irreversible obstruction groups. In the reversible obstruction group, salbutamol caused an increase in the mean VA compared with placebo (P < 0.001). However, the mean KCO was reduced (P < 0.001). The mean change in DL ,CO was not significant (P > 0.05). A considerable reduction in DL ,CO was found after salbutamol in four subjects in the reversible group as a result of a minor increase in VA and substantial decrease in KCO. No statistical difference in pulse rate or arterial blood gases values was detected.
  
  
  CONCLUSIONS
  Salbutamol had no effect on the mean DL ,CO in any group. However, salbutamol may considerably reduce DL ,CO in some individuals with reversibility secondary to its effects on VA and KCO.
authors.affiliation: Respiratory Physiology Laboratory, Christchurch Hospital, Christchurch, New Zealand.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.forename: Josh
authors.initials: J
authors.lastname: Stanton
authors.forename: Lexin
authors.initials: L
authors.lastname: Wang
authors.forename: Lutz
authors.initials: L
authors.lastname: Beckert
authors.forename: Chris
authors.initials: C
authors.lastname: Frampton
authors.forename: Debbie
authors.initials: D
authors.lastname: Burton
authors.forename: Maureen P
authors.initials: MP
authors.lastname: Swanney
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000402:Airway Obstruction / Q000188:drug therapy / Q000503:physiopathology*; D000420:Albuterol / Q000494:pharmacology* / Q000627:therapeutic use; D001993:Bronchodilator Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002248:Carbon Monoxide / Q000378:metabolism; D005260:Female; D005541:Forced Expiratory Volume / Q000187:drug effects / Q000502:physiology; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011653:Pulmonary Diffusing Capacity / Q000187:drug effects* / Q000502:physiology; D012129:Respiratory Function Tests; D013147:Spirometry; D016896:Treatment Outcome; D014797:Vital Capacity / Q000187:drug effects / Q000502:physiology; D055815:Young Adult
chemical_list: D001993:Bronchodilator Agents; D002248:Carbon Monoxide; D000420:Albuterol
keywords: pulmonary diffusing capacity; respiratory function test; salbutamol; transfer coefficient for carbon monoxide (DL,CO/VA, KCO)