BACKGROUND: Staging of bronchiolitis obliterans syndrome is based on the decline of forced expiratory volume in 1 second, a measure of overall ventilatory capacity. A single staging system is applied to all lung recipients, regardless of the bias which can be caused by the native lung after single lung transplantation. METHODS: We determined the decline of graft function in single lung recipients by a combination of two methods: 133-Xe radiospirometry and dynamic spirometry. The forced expiratory volume in 1 second fraction of the transplant (FEV1tx) was calculated from the proportion of ventilation of the transplant (Vtx) and forced expiratory volume in 1 second. Eight single lung recipients were followed up for a median observation period of 17 months; bronchiolitis obliterans syndrome developed in four of them. RESULTS: The fractional decline of forced expiratory volume in 1 second of the transplant was significantly greater than the decline of forced expiratory volume in 1 second (p = 0.016) in all patients during the follow-up. In the patients with bronchiolitis obliterans syndrome, the mean decline in forced expiratory volume in 1 second was 1.1 L (39.5%), and in forced expiratory volume in 1 second of the transplant it was 0.9 L (55.8%). The measurement of forced expiratory volume in 1 second of the transplant suggested stage 2a and 3a dysfunction in two grafts in which the assessment of forced expiratory volume in 1 second indicated stage 1a bronchiolitis obliterans syndrome. In one patient, decrease of forced expiratory volume in 1 second of the transplant was suggestive of chronic dysfunction 4 months before it was diagnosed by biopsy and declined lung function. CONCLUSIONS: The assessment of forced expiratory volume in 1 second seems to underestimate the severity of chronic dysfunction in single lung grafts. Instead, the determination of forced expiratory volume in 1 second of the transplant with radioactive tracers provides selective information of the graft function, which could be used for clinical evaluation of bronchiolitis obliterans syndrome in single lung recipients.
BACKGROUND: Staging of bronchiolitis obliterans syndrome is based on the decline of forced expiratory volume in 1 second, a measure of overall ventilatory capacity. A single staging system is applied to all lung recipients, regardless of the bias which can be caused by the native lung after single lung transplantation. METHODS: We determined the decline of graft function in single lung recipients by a combination of two methods: 133-Xe radiospirometry and dynamic spirometry. The forced expiratory volume in 1 second fraction of the transplant (FEV1tx) was calculated from the proportion of ventilation of the transplant (Vtx) and forced expiratory volume in 1 second. Eight single lung recipients were followed up for a median observation period of 17 months; bronchiolitis obliterans syndrome developed in four of them. RESULTS: The fractional decline of forced expiratory volume in 1 second of the transplant was significantly greater than the decline of forced expiratory volume in 1 second (p = 0.016) in all patients during the follow-up. In the patients with bronchiolitis obliterans syndrome, the mean decline in forced expiratory volume in 1 second was 1.1 L (39.5%), and in forced expiratory volume in 1 second of the transplant it was 0.9 L (55.8%). The measurement of forced expiratory volume in 1 second of the transplant suggested stage 2a and 3a dysfunction in two grafts in which the assessment of forced expiratory volume in 1 second indicated stage 1a bronchiolitis obliterans syndrome. In one patient, decrease of forced expiratory volume in 1 second of the transplant was suggestive of chronic dysfunction 4 months before it was diagnosed by biopsy and declined lung function. CONCLUSIONS: The assessment of forced expiratory volume in 1 second seems to underestimate the severity of chronic dysfunction in single lung grafts. Instead, the determination of forced expiratory volume in 1 second of the transplant with radioactive tracers provides selective information of the graft function, which could be used for clinical evaluation of bronchiolitis obliterans syndrome in single lung recipients.