Pediatrics |

A Novel Protocol to Detect Impaired Ventilatory Response to Brief Exercise in Cystic Fibrosis FREE TO VIEW

Jen Jen Chen, MD; Shlomit Radom-Aizik, PhD; Szu-Yun Leu, PhD; John Moua, MD; Inderpal Randhawa, MD; Eliezer Nussbaum, MD; Dan Cooper, MD
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Miller Children's Hospital - Long Beach Memorial Cystic Fibrosis Center, Long Beach, CA

Chest. 2013;144(4_MeetingAbstracts):758A. doi:10.1378/chest.1705190
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SESSION TITLE: Hot Topics in Pediatic Pulmonology

SESSION TYPE: Original Investigation Slide

PRESENTED ON: Monday, October 28, 2013 at 01:45 PM - 03:15 PM

PURPOSE: Higher levels of aerobic fitness in patients with cystic fibrosis (CF) are associated with lower morbidity and mortality. Exercise training for CF is strongly recommended, but only sporadically implemented in the US. The poor correlation between peak or maximal VO2 and FEV1 in CF highlights a major gap in our understanding the relationship between fitness and lung mechanics. Using a novel exercise testing protocol designed to specifically stress ventilation during exercise, we hypothesized that exercise limitations due to impaired ventilatory function could be easily identified in CF.

METHODS: 9 CF patients (3 males and 6 females) and 7 controls (3 males and 4 females) participated in the study and performed 2 exercise studies on separate days: 1) a ramp progressive-exercise test to determine fitness, and 2) 10, 2-min bouts, of cycle ergometer exercise at a constant work rate (~70% of VO2max), interspersed with 1-min rest intervals. Gas exchange was measured breath-by-breath.

RESULTS: Only 2 of the CF patients versus all 7 controls were able to complete all ten 2-min exercise bouts. Compared to controls, CF patients had higher mean VE (51.7±11.7 vs. 37.6±7.9 L/min, p=0.013) during exercise and higher mean VE and HR during the recovery periods (VE 41.9±12.6 vs. 27.0±8.0 L/min, p=0.013; HR 160.3±12.6 vs. 136.7±17.2bpm, p=0.012).

CONCLUSIONS: Repeated exercise stressed ventilatory responses more dramatically in CF than controls. The inability of CF subjects to complete the exercise protocols and to rapidly recover from short bouts of exercise suggest an impaired ventilatory response which might be due to the increased ventilatory and physiologic dead space that accompanies CF.

CLINICAL IMPLICATIONS: These new data can be used to construct exercise training protocols for CF patients that match their physiological capabilities and, therefore, may be more effective. Finally, the interval exercise test protocol more closely matches naturally occurring patterns of physical activity in humans than do traditional tests and could be useful to determine quantifiable biomarkers of fitness in CF.

DISCLOSURE: The following authors have nothing to disclose: Jen Jen Chen, Shlomit Radom-Aizik, Szu-Yun Leu, John Moua, Inderpal Randhawa, Eliezer Nussbaum, Dan Cooper

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