Surveillance fiberoptic bronchoscopy is performed to detect rejection in lung transplant recipients (LTX). Surveillance bronchoscopy has many drawbacks including invasiveness, cost, and complications. The analysis of exhaled breath constituents such as exhaled nitric oxide (NO) and carbon monoxide (CO), are known to be elevated in airway inflammation, but may serve as a noninvasive marker of graft infection or rejection. Previous reports of NO levels in LTX have shown mixed results. We hypothesized that the levels of NO are altered in the exhaled breath of LTX with allograft rejection when compared to healthy LTX controls.
We measured exhaled NO, CO, CO2, and O2 in the exhaled breath of 43 LTX [age (yrs±SD): 50±13, 19 males] presenting for routine surveillance bronchoscopy. LTX with graft rejection (n=7) were identified based on pathology samples. Measured exhaled NO, CO, CO2, and O2 in LTX with rejection [age (yrs±SD):48.1±10.36 3 males, 3 females] were compared to measured exhaled gases in healthy LTX (n=37) [age (yrs±SD):51.0±13, 16 males].
All patients had negative BAL and cultures for infection. Six patients (*n=7 events) had evidence of acute rejection by bronchoscopy. LTX were all on corticosteroids (average dose of 18 mg/day). The rejecting LTX had higher mean NO levels compared to the healthy non-rejecting LTX [NO (ppb±SE): rejecting LTX 11.2± 1.5, non-rejecting LTXR 8.3± .44, p=0.04]. The CO levels were not significantly different between the 2 groups [CO (ppm±SE): rejecting LTXR 1.6± 0.27, non-rejecting LTXR 1.3±0.07, p=NS]. The mean O2 levels were not significantly different between the 2 groups [O2 (%±SE): rejecting LTXR 17± 0.43, non-rejecting LTXR 17±0.12, p=NS]. After treatment for rejection, all repeated NO levels were noted to decrease compared to pretreatment measurements [NO(ppb±SE):6.8±1.28].CONCLUSIONS: During acute graft rejection, NO levels are elevated compared to non-rejecting grafts. After treatment for acute rejection, NO levels decrease to similar levels found in non-rejecting individuals.
Serial measurements of exhaled gases may be a useful, non-invasive method for monitoring graft function.
M.M. Budev, None.