Figure 5.

Using the modified splitter to normalize tidal volume in two patients with mismatched lung compliance. (a) In this experiment, two patients with mismatched respiratory compliances are connected via the modified splitter to the ventilator. The target tidal volume in all cases is that achieved when ventilating normal lungs in the model (490 ml). The following mismatched pairs were studied: Lung Model A + Lung Model B; Lung Model A + Lung Model C; Lung Model A + Lung Model D. (b) Pressure–time, tidal volume–time and flow–time graphs. Ventilation was performed in pressure control mode with, initially, PIP 15 cmH₂O, PEEP 5 cmH₂O, RR 15 breaths/min, I : E ratio 1 : 2 (not shown). Subsequently, PIP was progressively increased, until the target tidal volume was reached in Patient 2 with the lower compliance. At this stage, tidal volume was too large in Patient 1 (not shown) and the variable resistance in the Patient 1 inspiratory limb was therefore increased to normalize tidal volume also for Patient 1.