0108. Patients' response to changes in ventilator support. A modelling approach

Methods A set of mathematical models including pulmonary gas exchange, acid-base chemistry of blood and cerebrospinal fluid, blood oxygenation, O2 and CO2 transport and storage, ventilation, muscle function and chemoreflex respiratory drive were combined. The set of models was used to simulate changes in support during volume and pressure support ventilation. The model set was evaluated in 12 and 5 patients on volume and pressure support respectively. Ethical approval was obtained from the committee of Mid-Jutland, Denmark. Patient or relatives and general practitioners consent was obtained. For each patient, measurement of pulmonary gas exchange was followed by a series of up to 5 step modifications in the level of ventilator support, with these steps being 50 ml, for volume support, or 2 cm H2O for pressure support. Each level was maintained for 15 minutes, and arterial blood gases measured. Airway pressure, flow,