Lung transplantation is a therapeutic option for patients with end-stage idiopathic pulmonary fibrosis (IPF). Patients with advanced disease have severe hypoxemia and require increasing oxygen supplementation. IPF patients with advanced disease and severe hypoxemia have high mortality if not transplanted. Some recipients of single lung transplant (SLT) with IPF in the remaining native lung show persistent exertional hypoxemia after transplant despite a viable lung graft. The purpose of this study was to investigate intra-pulmonary right-to-left (R-L) shunting as a cause of hypoxemia among recipients of SLT and among patients with severe IPF evaluated for SLT.
Retrospective review of clinical data from 9 patients with IPF who underwent contrast echocardiogram to investigate persistent hypoxemia post SLT or severe hypoxemia while evaluated for SLT, showing intrapulmonary R-L shunting.
Four SLT recipients and 5 SLT candidates with IPF were found to have echocardiographic finding of intrapulmonary (R-L) shunt evidenced by presence of air contrast visible on left heart 6-8 beats after injection, contributing in minor to major degree to either resting or exercise hypoxemia. When evaluated for transplant their PFT’s averaged FVC=49±21% and DLco=30±8%. Resting PaO2/FiO2 ratio averaged 263±83. Resting PA mean = 28±12 mmHg. When shunting was diagnosed the average was Qs/Qt=22±8%.CONCLUSIONS: Patients with end stage IPF and hypoxemia may have intrapulmonary shunting from vascular dilatations or malformations likely derived from pathological vascular remodeling, contributing to hypoxemia from diffusion impairment and VQ mismatch. This physiologic abnormality will persist in the native lung of SLT recipients and may produce exertional hypoxemia despite normal functioning graft.
If significant intrapulmonary shunting is present in IPF candidates for transplant, a double lung transplant may be preferable.
C.A. Keller, None.