In this study, we found a small but statistically significant decrease in oxygen saturation during both AE and PE in patients with COPD. Meal-induced desaturation was statistically greater during AE than PE, but the difference was small in absolute terms. Episodic desaturation may be more significant during eating as evidenced by a lower mean lowest SpO2 during both AE and PE compared with corresponding baseline values. All patients also spent more time at saturations below 90% during eating. We also noted that patients with more severe COPD tend to have more unfavourable oxygen parameters during eating, but this is because they start off at a lower baseline oxygen saturation.
Our findings support and extend those of other investigators who have evaluated meal-related desaturation in patients with COPD . Flick and Block found significant declines in SpO2 with various activities during continuous daytime monitoring in 10 patients with COPD. In two patients changes in saturation as great as 15% were found while eating. Brown et al studied SpO2 more systematically during meals in 33 patients with COPD. The patients in that study had more severe COPD than the patients in the present study, and therefore had lower mean values for FEV1 and baseline oxygen saturation compared with those in this study. Similar to our results mean SpO2 decreased significantly, but by only 1.8% during eating. However, despite this modest decline, there was a subgroup of patients (seven of 33) whose change in SpO2 was 4% or greater, suggesting clinically significant desaturation.