Page | 1
EGAN'S FUNDAMENTALS OF
RESPIRATORY CARE CHAPTER 11
QUESTIONS WITH DETAILED VERIFIED
ANSWERS
When is the Transpulmonary Pressure P(TP) difference the same as the
Transaveoloar pressure P(TA) difference? Ans: When the movement of
air into and out of the lungs is static the Transpulmonary Pressure
difference is the same as the Transaveolar Pressure difference.
If a person is on a mechanical ventilator, how can you obtain the
Transpulmonary Pressure difference. Ans: By performing an inspiratory
or expiratory hold maneuver.
What is Elastance Ans: A measure of the distensibility of the lungs and
the thorax
How do we calculate the Elastance? Ans: Elastance = change in
Pressure/change in Volume
How do we measure compliance? Ans: Compliance = change in Volume/
change in Pressure
What is Resistance? Ans: A measure of airflow and tissue resistance
How do we calculate Resistance? Ans: Resistance = change in Pressure /
change in flow
How do we measure flow? Ans: Flow = change in volume / unit of time
What does the equation delta pressure = (Elastance x delta volume) +
(Resistance x delta flow) Ans: both values on the right side of the
equation reduce to changes in pressure. When these changes in pressure
are added, they represent the loads against which the respiratory
muscles and/or ventilator must work to achieve gas movement.
, Page | 2
What is the consequence of a patient that has a high elastance or a high
resistance? Ans: The pressure needed to move gas will need to be high.
Using your own words describe the equation of motion for the respiratory
system. Ans: It is a measure of the pressure difference required to
move air into or out of the lungs in a single breath.
Provide the formula for the simplified equation of motion Ans: delta
Pressure = (Elastance delta Volume) + (Resistance delta Flow)
Describe the model of the respiratory system used to create the
simplified equation of motion. Ans: a single airway connected to a single
alveoli surrounded by the pleural space
1) The Pressure measured at the opening of the airway is the Pressure at
airway opening (abbreviation: AO).
2) The Pressure measured in the alveoli is the Pressure Alveolar
(abbreviation: A).
3) The Pressure measured at the body surface is the Pressure Body
Surface (abbreviation: BS)
4) The Pressure measured in the pleural space (abbreviated: pl)
Define the Transrespiratory Pressure Ans: The pressure difference
between the pressure measured at the airway opening and the pressure
measured at the body surface (abbreviation: TR)
In the Transrespiratory Pressure equation why does P(AO) come before
P(BS) Ans: In order to dictate the direction of flow at the end of
inspiration
What is the equation for Transrespiratory Pressure Ans: P(TR) = P(AO) -
P(BS)
What is the term that defines the pressure difference between the Airway
Opening and the Alveoli in Fg11.1. Ans: The Transairway pressure
P(TAW)
EGAN'S FUNDAMENTALS OF
RESPIRATORY CARE CHAPTER 11
QUESTIONS WITH DETAILED VERIFIED
ANSWERS
When is the Transpulmonary Pressure P(TP) difference the same as the
Transaveoloar pressure P(TA) difference? Ans: When the movement of
air into and out of the lungs is static the Transpulmonary Pressure
difference is the same as the Transaveolar Pressure difference.
If a person is on a mechanical ventilator, how can you obtain the
Transpulmonary Pressure difference. Ans: By performing an inspiratory
or expiratory hold maneuver.
What is Elastance Ans: A measure of the distensibility of the lungs and
the thorax
How do we calculate the Elastance? Ans: Elastance = change in
Pressure/change in Volume
How do we measure compliance? Ans: Compliance = change in Volume/
change in Pressure
What is Resistance? Ans: A measure of airflow and tissue resistance
How do we calculate Resistance? Ans: Resistance = change in Pressure /
change in flow
How do we measure flow? Ans: Flow = change in volume / unit of time
What does the equation delta pressure = (Elastance x delta volume) +
(Resistance x delta flow) Ans: both values on the right side of the
equation reduce to changes in pressure. When these changes in pressure
are added, they represent the loads against which the respiratory
muscles and/or ventilator must work to achieve gas movement.
, Page | 2
What is the consequence of a patient that has a high elastance or a high
resistance? Ans: The pressure needed to move gas will need to be high.
Using your own words describe the equation of motion for the respiratory
system. Ans: It is a measure of the pressure difference required to
move air into or out of the lungs in a single breath.
Provide the formula for the simplified equation of motion Ans: delta
Pressure = (Elastance delta Volume) + (Resistance delta Flow)
Describe the model of the respiratory system used to create the
simplified equation of motion. Ans: a single airway connected to a single
alveoli surrounded by the pleural space
1) The Pressure measured at the opening of the airway is the Pressure at
airway opening (abbreviation: AO).
2) The Pressure measured in the alveoli is the Pressure Alveolar
(abbreviation: A).
3) The Pressure measured at the body surface is the Pressure Body
Surface (abbreviation: BS)
4) The Pressure measured in the pleural space (abbreviated: pl)
Define the Transrespiratory Pressure Ans: The pressure difference
between the pressure measured at the airway opening and the pressure
measured at the body surface (abbreviation: TR)
In the Transrespiratory Pressure equation why does P(AO) come before
P(BS) Ans: In order to dictate the direction of flow at the end of
inspiration
What is the equation for Transrespiratory Pressure Ans: P(TR) = P(AO) -
P(BS)
What is the term that defines the pressure difference between the Airway
Opening and the Alveoli in Fg11.1. Ans: The Transairway pressure
P(TAW)
