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
