Effect of intravenous antibiotics on exercise tolerance (3-min step test)) in cystic fibrosis

Pediatr Pulmonol. 2001 Jul;32(1):38-43. doi: 10.1002/ppul.1086.


Most children with cystic fibrosis (CF) feel better and display more energy after a course of intravenous antibiotics (IVABs), but this is not always reflected by a satisfactory improvement in lung function. We assessed the change in exercise tolerance after treatment with IVABs using the 3-min step test, and compared it with changes in spirometric lung function and arterial oxygen saturation (SaO(2)). Thirty-six children (mean age, 13.8 years) were enrolled from two tertiary CF centers during an inpatient stay for IVABs. After 10-14 days of treatment, there was a significant improvement in median FEV(1) from 43% to 57% of predicted values (P < 0.0001), and median FVC from 66% to 73% of predicted values (P < 0.0001), while median SaO(2) significantly increased from 95% to 96.5% (P < 0.05). This was accompanied by a reduction in resting heart rate (median 118 bpm to 109 bpm, P < 0.005) and subjective breathlessness at rest (median visual analogue score 2.2 to 0.8, P < 0.005). All outcomes of exercise tolerance were improved after IVABs. There was a reduction in maximum heart rate (median 156 bpm to 150 bpm, P < 0.05) and an increase in minimum SaO(2) (median 93.5% to 94.5%, P = 0.08) measured during the step test. There was also a reduction in subjective breathlessness (median visual analogue score of 5.5 to 4.2, P < 0.005) and objective breathlessness (median 15-count score of 3 to 2, P < 0.0001) measured immediately after the step test. Exercise testing was a useful outcome measure for monitoring effectiveness of inpatient therapy, and complemented spirometry and SaO(2) monitoring. The simple ward-based 3-min step test was found to be a particularly suitable method for measuring changes in exercise tolerance in children with CF.

Publication types

  • Clinical Trial

MeSH terms

  • Adolescent
  • Anti-Bacterial Agents*
  • Child
  • Cystic Fibrosis / drug therapy*
  • Cystic Fibrosis / physiopathology
  • Drug Therapy, Combination / administration & dosage
  • Drug Therapy, Combination / therapeutic use*
  • Exercise Test
  • Exercise Tolerance / drug effects*
  • Female
  • Forced Expiratory Volume / drug effects
  • Heart Rate / drug effects
  • Humans
  • Injections, Intravenous
  • Male
  • Oxygen / blood
  • Prospective Studies
  • Respiratory Function Tests
  • Treatment Outcome


  • Anti-Bacterial Agents
  • Oxygen