Ventilation–perfusion effects of negative-pressure ventilation: insights from an experimental rat model

Authors: Gergely H. Fodor, Ferenc Peták, Petra Somogyi, Bence Ballók, Fruzsina Kun-Szabó & József Tolnai

This experimental study compares the physiological effects of negative-pressure ventilation (NPV) and positive-pressure ventilation (PPV) on ventilation–perfusion matching in a rat model. Using controlled conditions with varying end-expiratory pressure (EEP), the study assessed gas exchange and capnographic parameters, demonstrating that NPV resulted in higher PaO₂ and lower PaCO₂ compared with PPV. These improvements were associated with reduced dead space ventilation and more favourable capnographic indices, suggesting more efficient ventilation–perfusion distribution under NPV.

The findings further show that increasing EEP during PPV worsened ventilation heterogeneity and dead space, whereas equivalent lung expansion achieved with NPV had a smaller detrimental effect. However, NPV was associated with increased intrapulmonary shunting at higher negative EEP levels. Overall, the study supports the physiological advantages of NPV in enhancing gas exchange and ventilation–perfusion matching, while highlighting potential limitations related to excessive negative pressures, with implications for the development of lung-protective and noninvasive ventilation strategies.