title: Haemodynamic responses to salbutamol and isometric exercise are altered in young adults with mild asthma.
abstract: OBJECTIVE
  Tolerance to the haemodynamic effects of regularly inhaled beta(2) agonists has been reported in a research setting. It is unclear whether cardiovascular responses in adults with asthma are influenced by their use in routine clinical practice. This study aimed to characterise the effects of acute salbutamol administration on systemic haemodynamics in adults with mild asthma who were receiving intermittent beta(2) agonist treatment.
  
  
  METHODS
  Ten patients with mild asthma and ten healthy age and sex-matched controls were recruited to a randomised placebo-controlled double-blind two-way crossover study. Each received salbutamol 200 mug or placebo, then performed sustained isometric handgrip exercise as an adrenergic cardiovascular stimulus. Heart rate and blood pressure responses were observed during rest and exercise, and cardiac index and systemic vascular resistance index were measured using non-invasive impedance cardiography.
  
  
  RESULTS
  Isometric exercise caused a greater increase in heart rate (12+/-3 vs. 8+/-3 bpm, P<0.01) and diastolic blood pressure (19+/-3 vs. 12+/-3 mmHg, P<0.01) in patients with asthma compared with healthy controls. Salbutamol administration significantly increased heart rate, blood pressure and cardiac index in healthy controls, but these responses were attenuated in patients with asthma.
  
  
  CONCLUSIONS
  These findings indicate that adults with asthma, who are receiving intermittent beta(2) agonist treatment, have a greater cardiovascular responses to sympathetic stimulation, and haemodynamic tolerance to acute salbutamol administration.
authors.affiliation: Clinical Pharmacology Unit and Research Centre, The University of Edinburgh, Edinburgh, UK. stephen.waring@ed.ac.uk
authors.forename: W Stephen
authors.initials: WS
authors.lastname: Waring
authors.forename: Rachel B
authors.initials: RB
authors.lastname: Leigh
mesh_terms: D000280:Administration, Inhalation; D000318:Adrenergic beta-Agonists / Q000494:pharmacology* / Q000627:therapeutic use; D000328:Adult; D000420:Albuterol / Q000494:pharmacology* / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy*; D001794:Blood Pressure / Q000187:drug effects*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male
chemical_list: D000318:Adrenergic beta-Agonists; D000420:Albuterol