How are tidal volume and inspiratory flow adjusted?
The ventilator uses a fixed inspiratory flow for mandatory breaths. When you change the tidal volume control, you are actually adjusting inspiratory time. The longer the inspiratory time, the more flow is delivered and the higher the tidal volume. The inspiratory flow is set at 36 liters per minute (600 ml per second). A one second breath is thus 600 ml in size. A two second breath is 1,200 ml. The set tidal volume is always delivered regardless of the patient’s lung compliance or resistance, unless the pressure limit is reached.
