The effects of pressure- versus volume-controlled ventilation on ventilator work of breathing

Table 1 MW of ventilation (cmH2O.L) with different flow waveforms (decelerating, square, and sinusoidal) with three types of lung mechanics

Pressure setting	Inspiratory flow waveform	Normal lung R 10 cmH2O/L/s, C 0.1 L/cmH2O	Restrictive lung diseases R 10 cmH2O/L/s, C 0.05 L/cmH2O	Obstructive lung diseases R 20 cmH2O/L/s, C 0.1 L/cmH2O
t_r 0.01 s, PS 10 cmH2O	Decelerating Square Sinusoidal	6.17 5.81 6.71	4.18 3.57 3.99	3.86 3.77 4.48
t_r 0.1 s, PS 10 cmH2O	Decelerating Square Sinusoidal	4.98 4.40 5.08	3.11 2.44 2.72	3.23 2.99 3.55
t_r 0.01 s, PS 20 cmH2O	Decelerating Square Sinusoidal	24.69 23.23 26.85	16.71 14.28 15.95	15.44 15.09 17.91
t_r 0.1 s, PS 20 cmH2O	Decelerating Square Sinusoidal	19.92 17.57 20.31	12.44 9.74 10.88	12.90 11.96 14.20

Also illustrated 2 levels of pressure support and 2 rise times. The square flow waveform has the smallest MW for all lung conditions. In normal and restrictive lungs the largest MW results from decelerating flow, while in obstructive lung condition the sinusoidal flow has the largest MW

ISSN: 1475-925X