Study objective: To evaluate exhaled nitric oxide (eNO)
during exercise in patients with stable COPD.
Outpatient evaluation in a rehabilitation center.
Patients: Eleven consecutive male patients with stable COPD
(age, 65 ± 6 years; FEV1, 56 ± 10% predicted). Eight
healthy (six men; age, 51 ± 16 years) nonsmoking, nonatopic
volunteers served as control subjects.
each subject, a symptom-limited cycle ergometry test was performed by
monitoring eNO with the tidal-breath method to assess eNO concentration
(Feno) and output (V̇no) at rest, peak
exercise, and recovery time.
Feno (9.8 ± 5.1 and 14.1 ± 6.3 parts per billion,
respectively) and V̇no (4.2 ± 2.0 and 5.9 ± 3.4
nmol/min, respectively) were lower, although not significantly, in COPD
patients than in control subjects. In both groups, Feno
significantly decreased whereas V̇no significantly
increased during exercise. Both variables returned to baseline during
the recovery time. Peak exercise V̇no, but not
Feno, was significantly lower in COPD patients than in
control subjects (7.9 ± 5.4 and 12.7 ± 6.0 nmol/min,
respectively, p < 0.05). The rise in V̇no was
weakly correlated to oxygen consumption
(V̇o2) both in control subjects
(r = 0.31, p = 0.002) and in COPD patients (r = 0.22,
p = 0.03). Feno showed an inverse correlation to
V̇o2 in both groups (r = −0.53,
p = 0.000; r = −0.31, p = 0.003 in control subjects and COPD
Conclusions: In patients with
mild and moderate COPD, eNO during exercise parallels that observed in
normal control subjects. V̇no, but not
Feno, is significantly reduced at peak exercise in COPD
patients as compared with control subjects. The long-term effects of
exercise training on eNO has to be evaluated by further