A ventilator is set to deliver a 600 mL tidal volume. The flow rate is set at 40 L/min and the ...

(Answer to Q. 1)  ANS: C
If you manipulate the formula: Flow = Volume change/Time to Volume/Flow = Time, and use the numbers from this example, it can be shown that by increasing the flow rate the inspiratory time will decrease. Since the frequency remains constant, then the inspiratory time will decrease, thereby increasing expiratory time.

(Answer to Q. 2)  ANS: B
The inspiratory hold, inspiratory pause, or end-inspiratory pause is the maneuver that will main-tain air in the lungs and extend inspiration. Pressure limit allows pressure to rise but not exceed a pressure limit setting. Expiratory hold is the maneuver that will obtain the unintended positive end expiratory pressure (auto-PEEP) measurement. The ventilator pauses before delivering the next machine breath. Expiratory resistance is a resistance added to exhalation to mimic pursed-lip breathing.

(Answer to Q. 3)  ANS: D
The low exhaled tidal volume and minute volume alarms are active when the high pressure limit alarm is active. This occurs because reaching the set high pressure limit setting will end inspiration immediately by pressure cycling and thereby will decrease the volume delivered to the patient. When the high pressure limit alarm is active for several breaths, the low exhaled tidal volume and then the minute ventilation alarms will become active. The high pressure alarm will sound when airway resistance is elevated (e.g., asthma). A disconnect from the ventilator or a critical leak would cause the low peak inspiratory pressure alarms to ring. Improved lung compliance will lower the peak inspiratory pressure and may trigger a low pressure alarm.

(Answer to Q. 4)  ANS: D
The peak flow for this pressure supported breath is 40 L/min. The breath flow cycled at 20 L/min, which is 50 of the peak flow. Therefore, the flow-cycle setting is 50.

(Answer to Q. 5)  ANS: A
During pressure support ventilation, when a breath is delivered, the flow will begin to taper down after a very short period of time. When flow drops to a certain percentage of the initial peak flow the ventilator flow cycles out of inspiration. A time cycled breath is usually a breath that is con-trolled by the ventilator during pressure control ventilation. Pressure cycling is used for intermit-tent positive pressure breathing (Bird Mark 7). Volume cycling is utilized during ventilator breaths on certain ventilators.

All of these are right, thanks!