We also found that dyspnea increased with eating and was greater during AE than PE. The finding of similar changes in dyspnea with eating in our subjects when grouped according to severity is not surprising because perceived breathlessness varies considerably in these patients and correlation between dyspnea and FEV 1 has been shown to be weak in COPD.
The observed increased dyspnea even with PE may reflect the work performed during mastication and swallowing or the effect of abdominal distention after eating. It has been shown that during eating there is an irregular pattern of breathing and an increase in the volume of ribcage and abdomen, both of which have been postulated to contribute to dyspnea . The greater effect of AE may once again be explained by considering eating to be a low level exercise involving the upper extremities. Several studies have shown the importance of arm position on ventilation under different conditions . Even in normal subjects arm elevation results in increased ventilatory and metabolic demands similar to those of mild exercise and a disproportionate increase in the diaphragmatic contribution to the generation of ventilatory pressures . This is of particular importance in patients with COPD whose diaphragms are less effective. In such individuals, Celli et al have reported that upper extremity exertion may lead to dyssynchronous thoracoabdominal breathing and dyspnea, possibly due to the extra burden on the diaphragm as accessory muscles are recruited to support the arms and torso.