Figure 3
From: Effects of the components of positive airway pressure on work of breathing during bronchospasm
On the left is a tracing of the summed signal from respiratory inductive plethysmography used for calculating changes in end-expiratory lung volume (EELV). The arrow labeled 'ON' depicts the switch from spontaneous breathing to the initiation of 10 cmH2O of inspiratory positive airway pressure (IPAP), expiratory positive airway pressure (EPAP), or continuous positive airway pressure (CPAP). The arrow labeled 'OFF' depicts the removal of positive airway pressure and return to spontaneous breathing. Changes in EELV were quantified by measuring changes in the baseline portion of the tracing. The changes in EELV induced by the addition (ON) and removal (OFF) of positive airway pressure were averaged, and the values are reported in Fig. 7. The increase in height of the summed signal represents changes in tidal volume (Vt), as measured using plethysmography, but these values were not measured for these experiments. On the right is a graph comparing plethysmographically derived summed signal measurements of changes in EELV with spirometer-derived values in three pharmacologically paralyzed animals during both inflation and deflation of the lungs.