Comparison of two methods to assess transdiaphragmatic pressure at different levels of work of breathing

A standard way to assess patient's work of breathing is the calculation of the inspiratory pressure-time-product (PTPinsp) which requires knowledge of the transdiaphragmatic pressure (Pdi). We designed the Occlusion+Delta (O+D) method to assess Pdi non-invasively. For its validation we compared PTPinsp from the proposed assessment (rPdi) and from Pdi measured with an invasively introduced gastro-oesophageal balloon catheter, giving especial attention to differences related to the defined levels of effort.