The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

DIAGNOSTIC RELIABILITY OF "TIME TO RECOVER" FROM EXERCISE IN ASTHMATIC CHILDREN


Jason Allen, RRT, Donald Kennerly, M.D., Mark Millard, M.D., Frank Brancaccio, M.D., Mary Hart, RRT. Baylor Asthma and Pulmonary Rehab Center Dallas, Texas

Background:  Identifying pediatric patients with asthma in the absence of objective data is clinically challenging. Hypothesis: Children with symptoms suggestive of asthma who complain of exercise limitation can be differentiated between exercise triggered asthma and deconditioning based on self-reported "time to recover" (TTR).

Method:
Elementary school children with symptoms suggestive of asthma were identified using a modified ISAAC questionnare. The day of testing, two questions were asked to each child : "Do you ever have to stop exercising because of difficulty breathing?" and, if so, "How long does it take before you are able to resume exercise?". Baseline FEVl, heart rate, O2 saturation, and breath sounds were recorded prior to exercise. The subjects were then asked to perform a 10 minute "free" run to asses for exercise triggering. Subsequent FEVl and vital signs were then checked at 1, 5 and 10 minutes post exercise. Exercise challenge was considered positive if there was a ≥10% drop from baseline FEV1 or ≥ 15% improvement from baseline FEV1 post bronchodilator. (Children with asthma symptoms were given 2 puffs of albuterol).

RESULTS:
Of the 81 subjects tested, 63 reported short TTR (< 10 min, mean = 2.8 min, geometric mean = 2.3 min) and 18 reported long TTR (≥ 10 min, mean = 21.min, geometric mean = 15.min) prior to exercise. Negative exercise challenges were recorded in 56 (89%) of the subjects reporting short TTR. Positive exercise challenges were recorded in 10 (55%) of the subjects reporting long TTR. However, 6 of the 8 false negatives (long TTR with negative exercise challenge) were on daily asthma medication. So, if patients with a previous diagnosis of asthma are excluded, the positive predictive value improves from 56% to 82%. These findings are highly statistically significant (c2p < 0.001) , indicating that short TTR is associated with absence of exercise induced airway obstruction while long TTR is predictive of positive exercise challenge, especially for patients who are not taking regular controller meds.

CONCLUSION:
Self reported short TTR is associated with a negative exercise challenge; long TTR is associated with a positive exercise challenge in subjects not on daily asthma medications. While this study tested a relatively small sample of children, it does suggest that TTR can be helpful in screening children for asthma and may be a useful clinical tool when spirometry and other objective and or costly tools are not available.

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