The Science Journal of the American Association for Respiratory Care

2009 OPEN FORUM Abstracts

INCREASED DEADSPACE DURING PEAK EXERCISE IN THE PRESENCE OF DYNAMIC HYPERINFLATION IN PATIENTS WITH EXPIRATORY FLOW LIMITATIONS

Noel I. Moreno1, Paul F. Nuccio1, Atul Malhotra2, Po-Shun Lee2; 1Pulmonary & Respiratory Care, Brigham and Women’s Hospital, Boston, MA; 2Pulmonary & Critical Care Division, Brigham and Women’s Hospital, Boston, MA

Background: Exercise-induced dynamic hyperinflation (DH) may be an under-recognized limitation to exercise in cardiopulmonary exercise test (CPET) by multiple physiologic mechanisms. While ventilatory and cardiac limitations have been previously reported, DH-induced deadspace increase has not been explored. Therefore, we hypothesize that DH increases pulmonary deadspace. Method: We conducted a chart review of CPET conducted in our center with inspiratory capacity (IC) measured at rest (ICrest) and at peak exercise (ICpeak). We arbitrarily define DH as ICpeak/ICrest <95%. Examined variables include O2pulse, peak VE, estimated deadspace fraction (Vd/Vt) at rest (Vd/Vtrest) and at peak exercise (Vd/Vtpeak). Intergroup comparisons are performed by Student’s t test. Results: We identified eleven consecutive CPETs performed since March 2009. Three of the cases met our criteria as having DH. Comparing the two groups, (DH vs. non-DH), Vd/Vt worsens at peak exercise compared to at rest (Vd/Vtpeak/ Vd/Vtrest ratios were 0.67 vs. 0.52, p=0.07). Other parameters, such as O2pulse % predicted (95% vs. 101%, p=0.29), VEpeak/MVV (0.64 vs. 0.81, p=0.10), were also found to be different but to a lesser degree. Conclusion: Exercise-induced DH is associated with increased deadspace at peak exercise. Such increases in deadspace may be an under-recognized limitation to exercise and inappropriately interpreted as pulmonary vascular abnormality in flow-limited patients with diseases such as COPD. Sponsored Research - None

You are here: RCJournal.com » Past OPEN FORUM Abstracts » 2009 Abstracts » INCREASED DEADSPACE DURING PEAK EXERCISE IN THE PRESENCE OF DYNAMIC HYPERINFLATION IN PATIENTS WITH EXPIRATORY FLOW LIMITATIONS