Figure 5.

Inspiratory effort breathing medical air or helium/oxygen 78/22 versus the breathing chamber compliance, with the resistive loss coefficient held constant at k = 6.6 (corresponding to two Rp5 resistors in series), a respiratory rate of 20 breaths/ min, and a tidal volume of 600 mL. Positive pressure support of 10 or 15 cm H₂O was supplied with a positive end-expiratory pressure of 5 cm H₂O. Error bars represent standard deviations around mean values.