Background: Non-invasive positive pressure ventilation (NPPV) is an accepted treatment option for chronic ventilatory failure due to restrictive thoracic disorders.
Objective: The impact of ventilation setting and the duration of ventilator use on changes in physiological and functional parameters has not yet been evaluated.
Methods: Effects of NPPV on body plethysmographic parameters, blood gas tension and inspiratory muscle function up to 12 months were analyzed in 44 patients with thoracic cage abnormalities in a clinical stable condition. Furthermore, the influence of ventilator parameters and the duration of ventilator use on these changes was determined.
Results: A significant improvement in blood gas parameters (PaCO(2), PaO(2) and base excess; p < 0.001), lung volumes (VC, TLC and FEV(1); p < 0.001) and inspiratory muscle function (PI(max), P(0.1); p < 0.01 and p < 0.05) was found after 3.8 +/- 0.8 months of treatment. As shown by a subgroup analysis, changes were already achieved within the first 3 months of NPPV and then remained stable over time. Improvements in VC were positively correlated with IPAP (r = 0.55; p < 0.001). Reduction in PaCO(2) was positively correlated with the quotient (IPAP - EPAP)/weight (r = 0.55; p < 0.001). No correlation could be detected between changes in functional parameters and the duration of ventilator use.
Conclusions: NPPV can improve blood gas parameters, lung volume and inspiratory muscle function in thoracic restrictive disorders. To best utilize the potential of NPPV treatment, it seems to be more effective to optimize pressure levels than to extend the duration of ventilation.