Question 1

What is the transairway pressure from the information found in the figure?

Accepted Answer

Transairway pressure = Peak inspiratory pressure - Plateau pressure = 35 cm H₂O - 20 cm H₂O = 15 cm H₂O.

Question 2

What is the static lung compliance when the returned tidal volume is 460 mL,the positive end-expiratory pressure is 8 cm H₂O,the peak inspiratory pressure is 27 cm H₂O,and the plateau pressure is 18 cm H₂O?

Accepted Answer

Static lung compliance = Volume ÷ (Plateau pressure - Positive end-expiratory pressure)= 460 mL ÷ (18 cm H₂O - 8 cm H₂O)= 460 mL ÷ 10 cm H₂O = 46 mL/cm H₂O.

Question 3

What is the compressibility factor for the patient circuit when the ventilator volume is set at 100 mL,the recorded peak inspiratory pressure is 41 cm H₂O,and the measured volume is 68 mL?

Accepted Answer

The compressibility factor of a patient circuit is the circuit's tubing compliance.Tubing compliance equals the measured volume divided by the measured peak inspiratory pressure (Tubing compliance = Volume/Peak inspiratory pressure).Tubing compliance = 68 mL ÷ 41 cm H₂O = 1.66 mL/cm H₂O.

Question 4

What is the static lung compliance when the returned tidal volume is 700 mL,the positive end-expiratory pressure is 10 cm H₂O,the peak inspiratory pressure is 45 cm H₂O,and the plateau pressure is 35 cm H₂O?

Accepted Answer

Static lung compliance = Volume ÷ (Plateau pressure - Positive end-expiratory pressure)= 0.7 L ÷ (45 cm H₂O - 10 cm H₂O)= 0.7 L ÷ 35 cm H₂O = 0.02 L/cm H₂O.

Question 5

Worsening lung compliance during volume-controlled ventilation would cause which of the following?

Accepted Answer

During volume-controlled ventilation,the peak inspiratory pressure generated by the delivery of the volume varies according to the characteristics of the lungs.Worsening lung compliance is indicative of stiffening lungs.This would cause more pressure to be generated during the delivery of a set volume.

Question 6

What is the compressibility factor for the patient circuit when the ventilator volume is set at 200 mL,the recorded peak inspiratory pressure is 72 cm H₂O,and the measured volume is 148 mL?

Accepted Answer

The compressibility factor of a patient circuit is the circuit's tubing compliance.Tubing compliance equals the measured volume divided by the measured peak inspiratory pressure (Tubing compliance = Volume/Peak inspiratory pressure).Tubing compliance = 148 mL ÷ 72 cm H₂O = 2.06 mL/cm H₂O.

Question 7

Pressure-support ventilation is classified as:
1)Flow cycled
2)Time triggered
3)Volume targeted
4)Pressure targeted
5)Patient triggered

Accepted Answer

In pressure-support ventilation,when the patient begins inspiration,inspiration is limited by pressure and ends when the patient's peak inspiratory flow decreases by a certain percentage (flow cycled).

Question 8

Worsening lung compliance during pressure-controlled ventilation would cause which of the following?

Accepted Answer

During pressure-controlled ventilation,the delivery of the volume varies according to the characteristics of the lungs.Worsening lung compliance is indicative of stiffening lungs.This would cause less volume to be delivered with the same set pressure.

Question 9

What is the volume that will reach the patient when the volume setting is 700 mL,the tubing compliance is 2 mL/cm H₂O,and the measured peak inspiratory pressure is 35 cm H₂O?

Accepted Answer

Volume lost because of tubing compliance is equal to the set volume minus the tubing compliance multiplied by the measured peak inspiratory pressure.Volume lost = 700 mL ?2- (2 mL/cm H₂O * 35 cm H₂O)= 700 mL ?2- 70 mL = 630 mL.

Question 10

During volume ventilation,peak inspiratory pressure is the pressure needed to overcome which two of the following factors?
1)Muscle pressure
2)Airflow resistance
3)Elastic recoil pressure
4)Transthoracic pressure

Accepted Answer

During volume ventilation,pressure increases as the volume is being delivered.The pressure at the end of inspiration,or peak inspiratory pressure,represents the pressure needed to overcome both airflow resistance and the elastic recoil pressure of the lungs and thorax.This concept is demonstrated in the equation of motion: Muscle pressure + Ventilator pressure = Elastic recoil pressure + Flow resistance pressure.Muscle pressure is the pressure generated by a person's muscles of ventilation to overcome elastic recoil pressure and airflow resistance.Transthoracic pressure is a pressure gradient between the pleural space and the body surface.During spontaneous breathing,it is the total pressure needed to expand or contract the lungs and chest wall together.

Question 11

Increasing the functional residual capacity of a spontaneously breathing patient to improve oxygenation can be accomplished by which of the following?

Accepted Answer

Continuous positive airway pressure is a technique in which a patient breathes spontaneously at an elevated baseline pressure.This increases the functional residual capacity and mean airway pressure and improves lung recruitment and oxygenation.

Question 12

Plateau pressure may be obtained during volume ventilation by using which of the following?

Accepted Answer

During volume ventilation,plateau pressure is obtained by using the maneuver that extends or delays exhalation by keeping the expiratory valve momentarily closed.This prevents the gas from leaving the circuit.The maneuver is known as an inspiratory pause,inspiratory hold,or inspiratory plateau.

Question 13

During pressure-targeted ventilation with a set pressure of 24 cm H₂O,the patient coughs.The ventilator responds by in which of the following ways?

Accepted Answer

It is a common misconception that the pressure-target setting cannot be exceeded during pressure-targeted ventilation.A cough by the patient can cause the pressure to rise above the set value.This is why it is vital that a safe upper pressure limit,or maximum safety pressure,be set at approximately 10 cm H₂O above the pressure-target setting during pressure ventilation.

Question 14

What is the static lung compliance when the returned tidal volume is 500 mL,the baseline pressure is zero,and the plateau pressure reading is 25 cm H₂O?

Accepted Answer

Static lung compliance = Volume ÷ (Plateau pressure - Positive end-expiratory pressure)= 0.5 L ÷ (25 cm H₂O - 0 cm H₂O)= 0.02 L/cm H₂O.

Question 15

Increased transairway pressure is associated with which two of the following changes?
1)Increased airway resistance
2)Decreased airway resistance
3)Increased static compliance
4)Decreased static compliance

Accepted Answer

Transairway pressure is the pressure required to overcome airflow resistance and is calculated by subtracting the plateau pressure from the peak inspiratory pressure.An increase in the peak inspiratory pressure with a constant plateau pressure increases the transairway pressure.Another way to increase transairway pressure would be to decrease the plateau pressure (i.e.,improved static compliance)and keep a constant peak inspiratory pressure.

Question 16

Which of the following is the formula for transairway pressure?

Accepted Answer

The transairway pressure is the pressure required to overcome airflow resistance and is calculated by subtracting the plateau pressure from the peak inspiratory pressure.

Question 17

Which of the following flow-termination settings for a pressure-supported breath that has a peak inspiratory flow of 30 L/min would allow enough time for a visible plateau on the pressure-time curve?

Accepted Answer

The longest inspiratory time provides a visible plateau on the pressure-time scalar.This is caused by a flow termination that takes the longest time to reach.The flow termination that is lowest provides the most visible plateau on a pressure-time scalar.Because 20% of the peak flow of 30 L/min is 6 L/min and 30% of 30 L/min is 9 L/min,the lowest flow in this case is 5 L/min.

Question 18

Improving lung compliance during pressure-controlled ventilation would cause which of the following?

Accepted Answer

During pressure-controlled ventilation,the delivery of the volume varies according to the characteristics of the lungs.Improving compliance makes it easier to deliver a volume with the same set pressure.

Question 19

The transairway pressure represents the pressure associated with which of the following?

Accepted Answer