Question 1

The pressure-time scalar shown in the figure could be caused by which of the following?

Accepted Answer

What is being shown in the figure is a peak pressure of 20 cm H₂O and then a very slow drop in the pressure over the course of approximately 1 second.Normally,as soon as the peak inspiratory pressure is reached,the pressure drops rapidly and remains at baseline until the next breath is given.A clogged expiratory filter will increase the resistance in the filter.This will cause there to be difficulty exhaling through this filter,showing up as a slow drop in pressure during the exhalation period.An inspiratory hold would cause there to be a plateau in the pressure-time scalar.Excessive secretions in the airway would elevate the peak inspiratory pressure to a point where the maximum safety pressure may be reached.The presence of negative end-expiratory pressure (NEEP)would pull the pressure down rapidly from the peak and drop it slightly below the baseline during that time.

Question 2

The ventilator that can provide a negative pressure during the very beginning of the exhalation phase is which of the following?

Accepted Answer

The Cardiopulmonary Venturi applies a negative pressure to the airway only during the very beginning of the exhalation phase.This facilitates removal of air from the patient circuit and is intended to reduce the resistance to exhalation throughout the circuit at the start of exhalation.

Question 3

What is the flow-cycle setting for the following pressure supported breath?

Accepted Answer

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%.

Question 4

The variable that controls exhalation is known as which of the following?

Accepted Answer

The baseline variable is the parameter that generally is controlled during exhalation.Although either volume or flow could serve as a baseline variable,pressure is the most practical choice and is used by all modern ventilators.

Question 5

The respiratory therapist is called to a patient's room because the "alarms are ringing." When the respiratory therapist arrives at the bedside,the high pressure limit,low exhaled tidal volume,and low exhaled minute volume alarms are active.The cause of these alarms is which of the following?

Accepted Answer

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.

Question 6

The most common method of terminating inspiration during pressure support ventilation is which of the following?

Accepted Answer

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 controlled by the ventilator during pressure control ventilation.Pressure cycling is used for intermittent positive pressure breathing (Bird Mark 7).Volume cycling is utilized during ventilator breaths on certain ventilators.

Question 7

When the maximum pressure limit is reached during volume ventilation,which of the following occurs?
1)Inspiratory time is decreased.
2)Volume delivered is decreased.
3)Inspiration continues until volume is delivered.
4)Pressure is held and the breath is volume cycled.

Accepted Answer

The maximum pressure limit is a safety mechanism used during volume ventilation to avoid excessive pressure in the lungs.When the pressure measured by the ventilator reaches the maximum pressure limit inspiration ends.This means that the inspiratory time will be decreased and the volume delivered will be less than the set volume.Therefore,reaching maximum pressure limit causes the delivered breath to be pressure cycled.

Question 8

A ventilator is set to deliver a 600 mL tidal volume.The flow rate is set at 40 L/min and the frequency is set at 10 breaths/min.If the flow rate is doubled and the patient is not assisting,which of the following will occur?

Accepted Answer

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.

Question 9

Which maneuver will maintain air in the lungs at the end of inspiration,before the exhalation valve opens?

Accepted Answer

The inspiratory hold,inspiratory pause,or end-inspiratory pause is the maneuver that will maintain 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.

Question 10

In pressure targeted ventilation the trigger variable for a patient who is sedated is which of the following?

Accepted Answer

When the patient is not triggering a breath,as with sedation,the set mechanical ventilator rate will be time-triggered based on the backup set rate.

Quiz 3: How a Breath Is Delivered