Lung mechanics and dyspnea after lung transplantation for chronic airflow obstruction

Single lung transplantation (SLT) is widely used to treat advanced chronic airflow obstruction (CAO). During exercise the native lung should increase end-expiratory lung volume (EELV) and result in a different respiratory sensation compared with double lung transplantation (DLT). Eight SLT recipients and 12 DLT recipients demonstrated a similar maximal work load and achieved V̇O₂. V̇Emax/MVV was 67.2 ± 4.0% in SLT recipients and 48.5 ± 3.6% in DLT recipients (p = 0.003). All SLT recipients demonstrated an increase in EELV during exercise, which was seen in only three of 12 DLT recipients. The change in absolute EELV from rest to peak exercise was different between SLT recipients (+0.37 ± 0.10 L) and DLT recipients (-0.10 ± 0.06, p = 0.0002). Tidal flow volume loop analysis demonstrated encroachment of the expiratory limb in four of seven SLT recipients but in only one of 12 DLT recipients. A lesser peak breathlessness in DLT recipients approached statistical significance (p = 0.051), although the relation of respiratory sensation versus V̇E or V̇O₂% predicted did not differ between the two groups. EELV increases in SLT recipients at peak exercise, although overall aerobic response is preserved and respiratory sensation is similar.