The effect of lung transplantation on the neural drive to the diaphragm in patients with severe COPD.

Little is known about the effects of lung transplantation (LT) on the neural drive to the diaphragm and on the endurance of respiratory muscles in patients with severe chronic obstructive pulmonary disease (COPD). The aim of this study was to evaluate these effects of single-lung (SLT) and double-lung transplantation (DLT). The neural drive to the diaphragm was assessed during fatiguing inspiratory threshold loading manoeuvres in six SLT recipients, six DLT recipients and seven patients with severe COPD, by using diaphragmatic surface electromyograms. During threshold loading, the patients had to generate 80% of their maximal transdiaphragmatic pressure with each breath. The endurance of inspiratory muscles was defined as the time from the beginning of a resistive breathing trial until exhaustion (t lim). In DLT recipients and even in SLT recipients (on both sides), neural activation of the diaphragm was significantly lower than in COPD patients (p < 0.05). However, no statistically significant difference in t lim was seen between LT recipients and COPD patients. The data suggest that single-lung and double-lung transplantations cause a significant decrease of the neural drive to the diaphragm, while the endurance of inspiratory muscles is well-preserved in patients with advanced chronic obstructive pulmonary disease. This may contribute to reduced sensation of inspiratory effort during ventilatory stress, thus improving the quality of life.