Question 1

Air accidentally trapped in the lungs due to mechanical ventilation is known as which of the following?

Accepted Answer

The definition of intrinsic PEEP is air that is accidentally trapped in the lung.Another name for this is auto-PEEP.Extrinsic PEEP is the positive baseline pressure that is set by the operator.Functional residual capacity (FRC)is the sum of a patient's residual volume and expiratory reserve volume and is the amount of gas that normally remains in the lung after a quiet exhalation.The plateau pressure is the pressure measured in the lungs at no flow during an inspiratory hold maneuver.

Question 2

Calculate the static compliance (Cs),in mL/cm H₂O,when PIP is 26 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ)is 19 cm H₂O,baseline pressure is 5 cm H₂O,and exhaled tidal volume (Vᴛ)is 425 mL.

Accepted Answer

CS = Vᴛ/(Pₚₗₐₜₑₐᵤ - EEP)

Question 3

Calculate the inspiratory time necessary to ensure 98% of the volume is delivered to a patient with a Cs = 40 mL/cm H₂O and the Rₐᴡ = 1 cm H₂O/(L/sec).

Accepted Answer

Time constant = C (L/cm H₂O)× R (cm H₂O/(L/sec)).98% of the volume will be delivered in 4 time constants.Therefore,multiply 4 times the time constant.

Question 4

Which of the following statements best defines elastance?

Accepted Answer

The opposite of compliance,elastance is the tendency of a structure to return to its original form after being stretched or acted on by an outside force.

Question 5

The statement that describes the alveolus shown in Figure 1-1 is which of the following?

1)Requires more time to fill than a normal alveolus.
2)Fills more quickly than a normal alveolus.
3)Requires more volume to fill than a normal alveolus.
4)More pressure is needed to achieve a normal volume.

Accepted Answer

The figure shows a low-compliant unit,which has a short time constant.This means it takes less time to fill and empty and will require more pressure to achieve a normal volume.Lung units that require more time to fill are high-resistance units.Lung units that require more volume to fill than normal are high-compliance units.

Question 6

Use this figure to compute the static compliance for an intubated patient with an inspiratory flow rate set at 70 L/min.

Accepted Answer

Use the graph to determine the PIP (34 cm H₂O)and the Pₚₗₐₜₑₐᵤ (20 cm H₂O).Convert the flow into L/sec (70 L/min/60 = 1.2 L/sec).Then,Rₐᴡ = (PIP - Pₚₗₐₜₑₐᵤ)/flow.

Question 7

Compute the inspiratory time necessary to ensure 100% of the volume is delivered to an intubated patient with a Cs = 60 mL/cm H₂O and the R_aw = 6 cm H₂O/(L/sec).

Accepted Answer

Time constant (TC)= C (L/cm H₂O)× R (cm H₂O/(L/sec)).100% of the volume will be delivered in 5 time constants.Therefore,multiply 5 times the time constant.

Question 8

What type of ventilator increases transpulmonary pressure (Pʟ)by mimicking the normal mechanism for inspiration?

Accepted Answer

Negative-pressure ventilation (NPV)attempts to mimic the function of the respiratory muscles to allow breathing through normal physiological mechanisms.Positive-pressure ventilation (PPV)pushes air into the lungs by increasing the alveolar pressure.High frequency oscillatory ventilation (HFOV)delivers very small volumes at very high rates in a "to-and-fro" motion by pushing the gas in and pulling it out during exhalation.High frequency positive-pressure ventilation (HFPPV)pushes in small volumes at high respiratory rates.

Question 9

The transairway pressure (Pᴛᴀ)shown in this figure is which of the following?

Accepted Answer

Pᴛᴀ= PIP - Pₚₗₐₜₑₐᵤ,where the PIP is 30 cm H₂O and the Pₚₗₐₜₑₐᵤ is 20 cm H₂O.The PEEP is 5 cm H₂O.

Question 10

Evaluate the combinations of compliance and resistance and select the combination that will cause the lungs to empty slowest.

Accepted Answer

Use the time constant formula,TC = C × R,to determine the time constant for each choice.The combination with the longest time constant will empty the slowest.The time constant for A is 0.1 second,B is 0.3 second,C is 0.15 second,and D is 0.24 second.To find out how many seconds for emptying,multiply the time constant by 5.

Question 11

The ventilator that functions most physiologically uses which of the following?

Accepted Answer

Air is caused to flow into the lungs with a negative pressure ventilator because the ventilator generates a negative pressure at the body surface that is transmitted to the pleural space and then to the alveoli. The transpulmonary pressure becomes greater because the pleural pressure drops. This closely resembles how a normal spontaneous breath occurs.

Question 12

Use this figure to compute the static compliance (Cs)for an intubated patient with an exhaled tidal volume (Vᴛ)of 500 mL.

Accepted Answer

Cs = Pₚₗₐₜₑₐᵤ - EEP; the Pₚₗₐₜₑₐᵤ in the figure is 20 cm H₂O and the PEEP is 10 cm H₂O.

Question 13

Calculate the static compliance (Cs),in mL/cm H₂O,when PIP is 47 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ)is 27 cm H₂O,baseline pressure is 10 cm H₂O,and exhaled tidal volume (Vᴛ)is 725 mL.

Accepted Answer

CS = Vᴛ/(Pₚₗₐₜₑₐᵤ - EEP)

Question 14

How many time constants are necessary for 95% of the tidal volume (Vᴛ)to be delivered from a mechanical ventilator?

Accepted Answer

One time constant allows 63% of the volume to be inhaled; 2 time constants allow about 86% of the volume to be inhaled; 3 time constants allow about 95% to be inhaled; 4 time constants allow about 98% to be inhaled; and 5 time constants allow 100% to be inhaled.

Question 15

Calculate airway resistance (Rₐᴡ)for a ventilator patient,in cm H₂O/L/sec,with the following information: Peak inspiratory pressure (PIP)is 20 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ)is 15 cm H₂O,PEEP is 5 cm H₂O,and set flow rate is 50 L/min.

Accepted Answer

Rₐᴡ = (PIP - Pₚₗₐₜₑₐᵤ)/flow and flow is in L/sec.

Question 16

Evaluate the combinations of compliance and resistance and select the combination that will cause the lungs to fill fastest.

Accepted Answer

Use the time constant formula,TC = C × R,to determine the time constant for each choice.The time constant for answer A is 0.1 sec.The time constant for answer B is 1 sec.The time constant for answer C is 0.03 sec,and the time constant for answer D is 0.3 sec.The product of multiplying the time constant by 5 is the inspiratory time needed to deliver 100% of the volume.

Quiz 1: Basic Terms and Concepts of Mechanical Ventilation

Air accidentally trapped in the lungs due to mechanical ventilation is known as which of the following?

Calculate the static compliance (Cs) ,in mL/cm H₂O,when PIP is 26 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ) is 19 cm H₂O,baseline pressure is 5 cm H₂O,and exhaled tidal volume (Vᴛ) is 425 mL.

Calculate the inspiratory time necessary to ensure 98% of the volume is delivered to a patient with a Cs = 40 mL/cm H₂O and the Rₐᴡ = 1 cm H₂O/(L/sec) .

Which of the following statements best defines elastance?

The statement that describes the alveolus shown in Figure 1-1 is which of the following? 1) Requires more time to fill than a normal alveolus. 2) Fills more quickly than a normal alveolus. 3) Requires more volume to fill than a normal alveolus. 4) More pressure is needed to achieve a normal volume.

Use this figure to compute the static compliance for an intubated patient with an inspiratory flow rate set at 70 L/min.

Compute the inspiratory time necessary to ensure 100% of the volume is delivered to an intubated patient with a Cs = 60 mL/cm H₂O and the R_aw = 6 cm H₂O/(L/sec) .

What type of ventilator increases transpulmonary pressure (Pʟ) by mimicking the normal mechanism for inspiration?

The transairway pressure (Pᴛᴀ) shown in this figure is which of the following?

Evaluate the combinations of compliance and resistance and select the combination that will cause the lungs to empty slowest.

The ventilator that functions most physiologically uses which of the following?

Use this figure to compute the static compliance (Cs) for an intubated patient with an exhaled tidal volume (Vᴛ) of 500 mL.

Calculate the static compliance (Cs) ,in mL/cm H₂O,when PIP is 47 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ) is 27 cm H₂O,baseline pressure is 10 cm H₂O,and exhaled tidal volume (Vᴛ) is 725 mL.

How many time constants are necessary for 95% of the tidal volume (Vᴛ) to be delivered from a mechanical ventilator?

Calculate airway resistance (Rₐᴡ) for a ventilator patient,in cm H₂O/L/sec,with the following information: Peak inspiratory pressure (PIP) is 20 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ) is 15 cm H₂O,PEEP is 5 cm H₂O,and set flow rate is 50 L/min.

Evaluate the combinations of compliance and resistance and select the combination that will cause the lungs to fill fastest.

Quiz 1: Basic Terms and Concepts of Mechanical Ventilation

Air accidentally trapped in the lungs due to mechanical ventilation is known as which of the following?

Calculate the static compliance (Cs) ,in mL/cm H₂O,when PIP is 26 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ) is 19 cm H₂O,baseline pressure is 5 cm H₂O,and exhaled tidal volume (Vᴛ) is 425 mL.

Calculate the inspiratory time necessary to ensure 98% of the volume is delivered to a patient with a Cs = 40 mL/cm H₂O and the Rₐᴡ = 1 cm H₂O/(L/sec) .

Which of the following statements best defines elastance?

The statement that describes the alveolus shown in Figure 1-1 is which of the following? 1) Requires more time to fill than a normal alveolus. 2) Fills more quickly than a normal alveolus. 3) Requires more volume to fill than a normal alveolus. 4) More pressure is needed to achieve a normal volume.

Use this figure to compute the static compliance for an intubated patient with an inspiratory flow rate set at 70 L/min.

Compute the inspiratory time necessary to ensure 100% of the volume is delivered to an intubated patient with a Cs = 60 mL/cm H₂O and the Raw = 6 cm H₂O/(L/sec) .

What type of ventilator increases transpulmonary pressure (Pʟ) by mimicking the normal mechanism for inspiration?

The transairway pressure (Pᴛᴀ) shown in this figure is which of the following?

Evaluate the combinations of compliance and resistance and select the combination that will cause the lungs to empty slowest.

The ventilator that functions most physiologically uses which of the following?

Use this figure to compute the static compliance (Cs) for an intubated patient with an exhaled tidal volume (Vᴛ) of 500 mL.

Calculate the static compliance (Cs) ,in mL/cm H₂O,when PIP is 47 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ) is 27 cm H₂O,baseline pressure is 10 cm H₂O,and exhaled tidal volume (Vᴛ) is 725 mL.

How many time constants are necessary for 95% of the tidal volume (Vᴛ) to be delivered from a mechanical ventilator?

Calculate airway resistance (Rₐᴡ) for a ventilator patient,in cm H₂O/L/sec,with the following information: Peak inspiratory pressure (PIP) is 20 cm H₂O,plateau pressure (Pₚₗₐₜₑₐᵤ) is 15 cm H₂O,PEEP is 5 cm H₂O,and set flow rate is 50 L/min.

Evaluate the combinations of compliance and resistance and select the combination that will cause the lungs to fill fastest.

Compute the inspiratory time necessary to ensure 100% of the volume is delivered to an intubated patient with a Cs = 60 mL/cm H₂O and the R_aw = 6 cm H₂O/(L/sec) .