Question 1

Calculate the static compliance using the information from the scalar below.

A) 10 mL/cm H₂O
B) 16 mL/cm H₂O
C) 20 mL/cm H₂O
D) 80 mL/cm H₂O

Accepted Answer

The volume is 400 mL,the plateau pressure (Pₚₗₐₜₑₐᵤ)is 25 cm H₂O,and the positive end-expiratory pressure (PEEP)is set at 5 cm H₂O.Static compliance = volume returned/Pₚₗₐₜₑₐᵤ.

Question 2

The volume curve on a volume-time scalar is consistently dropping below the baseline during exhalation.The first action to take is which of the following?
A) Measure the plateau pressure.
B) Measure the endotracheal (ET) tube cuff pressure.
C) Check the ventilator circuit for a leak.
D) Assess the patient for active exhalation.

Accepted Answer

When the volume drops below the baseline during exhalation,the cause could be active exhalation or an inspiratory time that is too long.Assessing the patient for active exhalation is the only viable answer given the choices.By doing the assessment the respiratory therapist can determine whether active exhalation is the cause.

Question 3

During pressure-controlled continuous mandatory ventilation (PC-CMV)the respiratory therapist observes the pressure-time scalar shown below.The most appropriate action to take is which of the following?

A) Adjust the inspiratory time.
B) Increase the flow rate setting.
C) Adjust the inspiratory rise time control.
D) Increase the peak inspiratory pressure setting.

Accepted Answer

The pressure-time scalar shows a pressure spike at the beginning of the pressure curve before the pressure adjusts to the set value.Adjusting the inspiratory rise time control will slow the rate at which pressure and flow exit the ventilator.This will reduce or eliminate the pressure spike.

Question 4

The respiratory therapist sees the following scalars on the screen of a ventilator providing support to a patient in the ICU.What action should the respiratory therapist take?

A) Switch to the volume-controlled intermittent mandatory ventilation (VC-IMV) mode.
B) Increase the flow rate to 60 L/min.
C) Decrease the sensitivity to 2 cm H₂O.
D) Increase the tidal volume to 550 mL.

Accepted Answer

The breaths shown are both patient-triggered.Negative deflections on the pressure-time scalar are present for both complete breaths shown.There is also a negative deflection between the two that did not result in a ventilator breath.A closer look at the amount of pressure required to trigger a ventilator breath shows that it is set at 10 cm H₂O.The negative deflection in the center of the pressure-time scalar demonstrates that the patient could not generate enough negative pressure to trigger a breath.Therefore,the sensitivity needs to be reduced to 2 cm H₂O.

Question 5

What is the inspiratory time for the ventilator breath shown in section B of the figure below?

A) 0.5 second
B) 1.0 second
C) 1.5 second
D) 2.0 seconds

Accepted Answer

Inspiration in section B of the figure is approximately 0.5 second.This can be found by dRₐᴡing a straight line through the beginning of the breath on all three of the scalars and a second line at the end of inspiration on each of the scalars as shown below:
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Question 6

What is the trigger variable for the "A" breath shown in the figure below?

A) Flow
B) Time
C) Pressure
D) Volume

Accepted Answer

There is no patient trigger noted; therefore,the trigger in this case is time.

Question 7

A patient is receiving full ventilatory support with volume ventilation.At 0700 the respiratory therapist observes the pressure-,volume-,and flow-time scalars shown in "A" below.Six hours later the respiratory therapist observes the scalars shown in "B." The most appropriate action to take is which of the following?

A) Increase the positive end-expiratory pressure (PEEP) level.
B) Check the circuit for a leak.
C) Administer a bronchodilator.
D) Switch to pressure ventilation.

Accepted Answer

All three scalars show signs of increased airway resistance.The pressure-time scalar shows an increase in peak inspiratory pressure (PIP).The volume-time scalar shows that it is taking longer for the patient to exhale all the volume.The flow-time scalar shows that the expiratory flow is very slow and takes a long time to rise to the zero baseline.

Question 8

Identify the sinusoidal (or sine)waveform in the figure below.

A) Figure A
B) Figure B
C) Figure C
D) Figure D

Accepted Answer

The sinusoidal waveform looks very much like the first half of a mathematical sine wave.

Question 9

The type of flow curve produced by volume ventilation with constant flow is which of the following?
A) Sinusoidal
B) Rectangular
C) Descending ramp
D) Exponential decay

Accepted Answer

Volume ventilation with a constant flow will produce a rectangular flow curve unless a different flow pattern is chosen.Pressure ventilation creates a descending curve that varies with both lung characteristics and patient flow demand.

Question 10

An inadequate flow setting during volume ventilation will cause which of the following to occur?
A) The volume curve will drop below the zero baseline.
B) The volume curve will not drop to the zero baseline.
C) The exhaled flow will take longer to rise to the zero baseline.
D) The pressure-time curve will appear concave during inspiration.

Accepted Answer

When the flow rate setting is inadequate,the pressure-time scalar takes a concave shape during inspiration.A volume curve dropping below baseline is indicative of active exhalation.A volume curve that ends above baseline indicates a leak.An exhaled flow curve that takes the entire expiratory time to rise back to zero baseline is indicative of increased airway resistance.

Question 11

The ventilator graphics generated by mechanical ventilation with pressure-controlled continuous mandatory ventilation (PC-CMV),rate 18,peak inspiratory pressure (PIP)25 cm H₂O,positive end-expiratory pressure (PEEP)5 cm H₂O,are shown in the scalars below.Interpretation of these scalars reveals which of the following?

A) The flow rate is set too high and should be reduced.
B) There is air trapping that could be due to a high respiratory rate.
C) The ventilator settings are appropriate and there are no problems.
D) There is a leak in the system that needs to be identified and corrected.

Accepted Answer

Breaths are beginning prior to the patient completely exhaling.This is shown on the flow-time scalar by the expiratory flow not having enough time to return to zero before the next breath is delivered.It is possible that this is caused by the set rate of 18 breaths/min and/or by an increased airway resistance.One can also conclude that there is unintended positive end-expiratory pressure (auto-PEEP)preset in this situation.

Question 12

What is the inspiratory time shown in the flow-time scalar below?

A) 0.5 second
B) 1 second
C) 1.5 second
D) 2 seconds

Accepted Answer

Inspiratory flow delivery stops at 1 second on this flow-time scalar.

Question 13

The peak inspiratory flow rate on the flow-time scalar below is which of the following?

A) 25 L/min
B) 40 L/min
C) 46 L/min
D) 55 L/min

Accepted Answer

If you draᴡ a line across the top of the square wave of the inspiratory flow scalar,the flow rate equals 46 L/min.

Question 14

The most important factor to affect the degree of resistance in the airways is which of the following?
A) Flow rate of the gas
B) Viscosity of the gas
C) Length of the airways
D) Diameter of the airways

Accepted Answer

The most important factor affecting the degree of airway resistance is the diameter of the airways.The mathematical law that determines this fact is Poiseuille's law.A large diameter airway will have low airway resistance and there will be a greater flow of gas.A small diameter airway will have high resistance and there will be a lower flow.

Question 15

Identify the improperly set ventilator parameter using the scalars shown below.

A) Mode
B) Flow rate
C) Sensitivity
D) Tidal volume

Accepted Answer

The breaths shown are both patient triggered.Negative deflections on the pressure-time scalar are present for both complete breaths shown.There is also a negative deflection between the two that did not result in a ventilator breath.A closer look at the amount of pressure required to trigger a ventilator breath shows that it is set too insensitive.In this situation the patient needs to generate a pressure of 10 cm H₂O below the baseline to trigger a breath.The negative deflection in the center of the pressure-time scalar demonstrates that the patient could not generate enough negative pressure to trigger a breath.Therefore,the sensitivity is not set properly.

Question 16

The two waveforms that are common for pressure scalars are which of the following?
A) Sinusoidal and ascending ramp
B) Rectangular and exponential rise
C) Descending ramp and ascending ramp
D) Exponential decay and descending ramp

Accepted Answer

Pressure waveforms are usually the rectangular or rising exponential type.

Question 17

The respiratory therapist observes the following pressure-time and flow-time scalars following a patient being intubated and placed on a mechanical ventilator using volume ventilation.The most appropriate action is which of the following?

A) Increase the set flow rate.
B) Switch to pressure control.
C) Increase the set tidal volume.
D) Change to a decelerating flow pattern.

Accepted Answer

When the flow rate setting is inadequate,the pressure-time scalar takes on a concave shape during inspiration when the patient is actively inhaling.In this case the demand exceeds the ventilator setting and capability.The inspiratory demand of the patient will be provided for by increasing the set flow.

Question 18

What is the expiratory time shown in the flow-time scalar below?

A) 1 second
B) 1.5 second
C) 2 seconds
D) 2.5 seconds

Accepted Answer

The first breath ends at 1 second and the second breath begins at 2.5 seconds.Therefore,the expiratory time is 2.5 seconds minus 1 or 1.5 second.

Question 19

The respiratory therapist observes the pressure-time scalar seen below.Wave A was generated at 1300 hour and wave B at 1600 hour.The action that is most appropriate for this situation is which of the following?

A) Add positive end-expiratory pressure (PEEP).
B) Change the endotracheal tube (ET).
C) Change to pressure-controlled continuous mandatory ventilation (PC-CMV).
D) Administer a bronchodilator.

Accepted Answer

When comparing the two waveforms it should be noted that the plateau pressures (P_plateau)are the same for both,15 cm H₂O.However,the peak inspiratory pressure (PIP)is higher in waveform B,35 cm H₂O,as opposed to waveform A,27 mm H₂O.This indicates an increase in transairway pressure (Pᴛᴀ)and therefore,airway resistance.The most appropriate answer is to administer a bronchodilator.If the ET tube was too small the Pᴛᴀ would have been consistently high from the start of mechanical ventilation.Adding PEEP or switching to pressure-controlled continuous mandatory ventilation (PC-CMV)would be appropriate if the P_plateau was increasing.

Question 20

Calculate the airway resistance (Rₐᴡ)using the information from the scalar below.

A) 0.9 cm H₂O/L/sec
B) 1.1 cm H₂O/L/sec
C) 22.4 cm H₂O/L/sec
D) 60 cm H₂O/L/sec

Accepted Answer

Airway resistance (Rₐᴡ)= Peak inspiratory pressure (PIP)- Plateau pressure (Pₚₗₐₜₑₐᵤ)/flow (L/sec).PIP = 40 cm H₂O; Pₚₗₐₜₑₐᵤ = 25 cm H₂O; flow = 40 L/min or 0.67 L/sec; Rₐᴡ = 15/0.67 = 22.4 cm H₂O/L/sec.

Quiz 9: Ventilator Graphics

Calculate the static compliance using the information from the scalar below.

The volume curve on a volume-time scalar is consistently dropping below the baseline during exhalation.The first action to take is which of the following?

During pressure-controlled continuous mandatory ventilation (PC-CMV) the respiratory therapist observes the pressure-time scalar shown below.The most appropriate action to take is which of the following?

The respiratory therapist sees the following scalars on the screen of a ventilator providing support to a patient in the ICU.What action should the respiratory therapist take?

What is the inspiratory time for the ventilator breath shown in section B of the figure below?

What is the trigger variable for the "A" breath shown in the figure below?

Identify the sinusoidal (or sine) waveform in the figure below.

The type of flow curve produced by volume ventilation with constant flow is which of the following?

An inadequate flow setting during volume ventilation will cause which of the following to occur?

What is the inspiratory time shown in the flow-time scalar below?

The peak inspiratory flow rate on the flow-time scalar below is which of the following?

The most important factor to affect the degree of resistance in the airways is which of the following?

Identify the improperly set ventilator parameter using the scalars shown below.

The two waveforms that are common for pressure scalars are which of the following?

The respiratory therapist observes the following pressure-time and flow-time scalars following a patient being intubated and placed on a mechanical ventilator using volume ventilation.The most appropriate action is which of the following?

What is the expiratory time shown in the flow-time scalar below?

The respiratory therapist observes the pressure-time scalar seen below.Wave A was generated at 1300 hour and wave B at 1600 hour.The action that is most appropriate for this situation is which of the following?

Calculate the airway resistance (Rₐᴡ) using the information from the scalar below.