Short term effect of a single dose of formoterol or tiotropium on the isolated nocturnal hypoxemia in stable COPD patients: a double blind randomized study.

Patients with stable chronic obstructive pulmonary disease (COPD) and diurnal PaO2 > 60 mmHg may have transient oxygen desaturation during sleep. The effect of bronchodilators on nocturnal hypoxemia is not known. The aim of this study was to evaluate if a single dose of Formoterol or Tiotropium, administered in the evening, could improve nocturnal hypoxemia in patients with stable middle/severe COPD. Thirty-seven patients (25 M/12 F; mean age 68.97 +/- 8.57, range 50-78; mean FEV1% of predicted 46.29 +/- 9.2) with PaO2 > 60 mmHg, but with significant oxygen desaturation during sleep and apnea/hypopnea index < or = 10 were selected. They randomly underwent three consecutive nocturnal pulsoxymetry: baseline and after taking placebo and 12 microg of Formoterol (20 pts) or 18 microg of Tiotropium (17 pts) in the evening. FEV1 and IC, measured after 1 h of taking bronchodilators, were significantly higher than placebo. The variation, with regards to baseline values, in mean heart rate and Lowest SpO2% measured after Tiotropium (-1.68 +/- 4.01 and 3.23 +/- 8.58 respectively) was higher (p < 0.05) than placebo (-0.108 +/- 2.85 and 0.29 +/- 7.05 respectively). Moreover, the trend time of SpO2% (measured by pulse-oximeter at each hour of total time registration) after Tiotropium was significantly higher than baseline or placebo (p < 0.01). Instead, the trend time of SpO2% after Formoterol, except for an initial transient hypoxemia fall, was similar to baseline condition and after placebo. Also the trend time of heart rate resulted significantly lower in the Tiotropium group, but higher in the Formoterol group. In conclusion, Formoterol does not seem to influence the nocturnal hypoxemia in stable COPD patients probably for the worsening V/Q ratio. On the contrary, a single dose of tiotropium seems to decrease the severity in the nocturnal desaturations in stable COPD patients probably due to the reduction in the nocturnal bronchial colinergic tone.