[Evaluation of correlation between pulmonary function testing and high resolution computed tomography in pulmonary alveolar proteinosis].

OBJECTIVE: Pulmonary alveolar proteinosis (PAP) is a rare respiratory disorder featured by lipoproteinaceous material accumulation within alveoli. Pulmonary function testing (PFT) and quantitative high resolution computed tomography (HRCT) are used in evaluation of the severity, development and treatment effects of PAP. METHODS: Seventeen patients (10 males, 7 females), aged from 15 to 51 years old, with PAP histopathologically proven by positive periodic acid Schiff reaction were studied in our institute from 2004 to 2007. PFTs and HRCT were performed in all patients. The quantitative parameters of HRCT included total lung volume (TLV), total lung mass (TLM), air-filling lung volume (AFLV), averaged lung density (ALD) and the ratio of air-filling lung volume to total lung volume (AFLV/TLV). The parameters of PFT included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC, diffusion capacity of carbon monoxide (D(L)CO), the ratio of D(L)CO to alveolar volume (D(L)CO/V(A)), total lung capacity (TLC), residual volume (RV), RV/TLC. A total of 24 dataset of the PFT and HRCT were collected. The correlation and regression between PFTs and HRCT were analyzed. PFT and HRCT parameters were compared before and after treatment with whole lung lavage in 6 of these patients. The data were expressed with mean +/- standard deviation and analyzed with SPSS 13.0 software. RESULTS: Restrictive ventilation function disorder and diffusion function disorder were found in patients with PAP, with more significant decline in D(L)CO (46.1% of predicted and abnormal rate 94.1%). Correlation between PFTs and HRCT parameters were found, with significance in ALD and FVC (r = -0.469, P = 0.021), TLM and FEV1 (r= -0.482, P = 0.017), AFLV/TLV and PEF (r = 0.511, P = 0.011), D(L)CO and D(L)CO/V(A) (r = 0.659, 0.692, P = 0.000, respectively). The highest correlation was found between D(L)CO/V(A) and AFLV (r = 0.525; P < 0.05). D(L)CO was markedly improved after the treatment of whole lung lavage, simultaneously found with varied improvement of quantitative parameters of HRCT measurements. CONCLUSIONS: Pulmonary function was impaired and correlated with abnormal appearance in HRCT in patients with PAP. Quantitative HRCT may be helpful in prediction of pulmonary function changes. Both techniques are important for the prognosis, outcome and follow-up studies of the disease.