Changes in pulmonary gas exchange in histiocytosis X patients depending on the type of ventilation disorders

Objective: To determine the mechanisms of pulmonary gas exchange in Histiocytosis X (HX) patients with different types of ventilation disorders. Material and methods: 84 HX patients have been examined: 64 men (mean age 31.7±1.41 yr) and 20 women (mean age 27.5±2.54 yr). The diagnosis was put on basis of morphological research of biopsy materials for 35 patients (12 video-assisted thoracoscopy and 23 open biopsy). Spirometry, bodyplethysmography, compliance and diffusion capacity measurement, scintigraphy and CT were carried out for all patients. Results: Under the results of spirometry, bodyplethysmography and compliance measurement the restrictive, obstructive and mixed ventilator patterns were determinate. In restriction both the DLCO (53.4±8.87% Pred) and the AV (69.6±6.71% Pred) significantly decreased, so their relationship changed slightly. In obstructive and mixed types the ratio DLCO and AV was normal, but the decrease in each of these components was more pronounced in mixed disorders group. For each patient the non-ventilated lung volume was calculated: TLCpleth-TLC HE. The maximum increase in a non-ventilated lung volume was observed in patients with obstructive type of ventilation disorders (1±0.48 l). In patients with restriction pattern non-ventilated lung volume was minimal (0.2±0.2 l). Conclusions: The functional picture of HX, in contrast to X-ray evidence of disease, is very diverse. Each type of ventilation disorders was characterized its own mechanism of changes in pulmonary gas exchange. In case of restriction it is reducing the gas exchange surface and in case of obstruction it is local and regional heterogeneity of ventilation-perfusion ratio changes.