RESUMEN
To study the effect of inspiratory flow, we gave 30 postoperative ventilated patients (ASA 1-2) aged 20-60 years old three kinds of inspiratory wave forms as I (square), II (decelerated) and III (sine) were. Each patient received all 3 kinds of wave in on particular order by random. We found these effects on the cardiovascular system. Sine wave: decreased blood pressure more than the others but not significantly (p > 0.01). The best oxygenation was from sine waves than decelerated and finally square (not significant). Ventilation: PaCP2 decreased least with decelerated wave and most with square wave a significantly change comparing the two (p < 0.01). There was no significant change in pH. Airway pressure; PIP, increased significantly in I more than III and II, P plateau was highest in III then I and II and P maw the difference was not significant in I, II and III nut highest in III.