Exam 2 Flashcards
________________ is simply the movement of air into and out of the lungs.
Spontaneous ventilation
What is this abbreviation?
Cdyn
Dynamic compliance
What is this abbreviation?
R
Resistance
What is this abbreviation?
PM
Pressure at the mouth
What is this abbreviation?
Pbs
Pressure at the body surface
What is this abbreviation?
Ppl
Intrapleural pressure
What is this abbreviation?
Cst
Static compliance
What is this abbreviation?
Pawo
Pressure at the airway opening; mouth pressure; mask pressure
What is this abbreviation?
Paw
Airway pressure
What is this abbreviation?
Palv
Alveolar pressure
Respiration is typically divided into what two categories?
- External respiration
- Internal respiration
For air to flow through a tube or airway, a _______________ must exist.
Pressure gradient
Air will always flow from the _____________ to the _________________.
Air will always flow from the high-pressure point to the low-pressure point.
A spontaneous breath is accomplished by contraction of the ______________________, which causes the expansion of the thorax.
Muscles of inspiration
Airway opening pressure is most often called __________________.
Mouth pressure or airway pressure
Define transpulmonary pressure.
The pressure difference between the alveolar space and the pleural space.
Define transthoracic pressure.
The pressure difference between the alveolar space or lung and the body’s surface.
What is the normal compliance is spontaneously breathing patients?
0.05 to 0.17 L/cmH2O or 150 to 170 mL/cmH2O
What is the normal compliance is intubated patients?
Males: 40 to 50 mL/cmH2O, up to 100 mL/cmH2O
Females: 35 to 45 mL/cmH2O, up to 100 mL/cmH2O
The compliance of any structure can be described as _____________________.
The relative ease with which the structure distends.
________________ is a measurement of the frictional forces that must be overcome during breathing.
Resistance
Ventilating pressures are commonly measured in what?
Centimeters of water
Define transairway pressure.
The pressure difference between the airway opening and the alveolus.
What is normally the intrapleural pressure at end expiration during spontaneous breathing?
-5 cmH2O
Define transrespiratory pressure.
The pressure difference between the airway opening and the body surface.
What are the two components of transrespiratory pressure?
- Transthoracic pressure
- Transairway pressure
Normally, what two types of forces oppose inflation of the lungs?
Elastic forces and frictional forces
Airway resistance is increased when __________________.
An artificial airway is inserted
The diameter of the airway lumen and flow of gas into the lungs can decrease as a result of:
- Bronchospasm
- Increased secretions
- Mucosal edema
- Kinks in the endotracheal tube
What involves the change of oxygen and carbon dioxide between an organism and its environment?
Respiration
To achieve a maximal inspiration, ____________________ must be used to compress the thorax.
Accessory muscles of inspiration
Explain external respiration.
It involves the diffusion and carbon dioxide between the alveoli and the pulmonary capillaries.
Internal respiration occurs at the _______________________________
Cellular level and involves the exchange of oxygen and carbon dioxide between the systemic capillaries and the cells of the body.
During spontaneous inspiration, contraction of the inspiratory muscles causes enlargement of the thorax resulting in a decrease in _____________________.
Intrapleural pressure and alveolar pressure
Gas flows out of the lungs during expiration because…
The pressure in the alveoli is higher than the pressure at the airway opening.
What is the atmospheric pressure at sea level?
760 mmHg or 1034 cmH2O
Body pressure is equal to zero unless:
The person is placed in a pressurized chamber or negative pressure ventilation
____________________ is the pressure in the potential space between the parietal and visceral pleurae.
Intrapleural pressure
What is the normal intrapleural pressure at the end of expiration?
-10 cmH2O
What is alveolar pressure during spontaneous inspiration?
About -1 centimeters of water
What is alveolar pressure during spontaneous expiration?
About +1 centimeters of water
__________________ represents the pressure that must be generated to overcome resistance to gas flow in the airways.
Transairway pressure
Air can be trapped in the lungs during mechanical ventilation if not enough time is allowed for exhalation. What is the most effective way to prevent this?
Monitor the pressure in the ventilator circuit at the end of exhalation.
What does it mean if no extrinsic PEEP is added and the baseline is greater than zero?
Air trapping or auto-PEEP is present
_______________ reflects the effect of the elastic recoil on the gas volume inside the alveoli and any pressure exerted by the volume in the ventilator circuit that is acted upon by the recoil of the plastic circuit.
Plateau pressure
When is plateau pressure measured?
After a breath has been delivered to the patient and before exhalation begins
To obtain the plateau pressure, the ventilator operator normally selects a control marked ___________________.
“Inflation hold” or “Inspiratory pause”
During positive pressure ventilation, the manometer rises progressively to a _______________________.
Peak pressure
Peak pressure is also called what?
- Peak Inspiratory Pressure
- Peak Airway Pressure
Sometimes the baseline pressure is higher than zero, such as when the ventilator operator selects a higher pressure to be present at the end of exhalation. What is this called?
Positive End-Expiratory Pressure (PEEP)
______________ is the highest pressure recorded at the end of inspiration.
Peak pressure
When does intrinsic peep usually occur?
When a patient does not have enough time to exhale completely before the ventilator delivers another breath
What are the three basic methods that have been developed to mimic or replace the normal mechanisms of breathing?
- Negative pressure ventilation
- Positive pressure ventilation
- High-frequency ventilation
The product of compliance and resistance is called a ________________.
Time constant
Because intrapleural pressures are often hard to obtain in a patient, what is typically used instead?
Esophageal pressure
Alveolar pressure is also called __________________.
Intrapulmonary pressure or lung pressure
Alveolar pressure normally changes as the ____________________ changes.
Intrapleural pressure
During spontaneous inspiration, what is the alveolar pressure?
-1 centimeters of water
During spontaneous expiration, what is the alveolar pressure?
+1 centimeters of water
Which pressure gradient represents the pressure required to expand or contract the lungs and the chest wall at the same time?
Transthoracic pressure
_________________ is the pressure required to maintain alveolar inflation and is therefore sometimes called alveolar distending pressure.
Transpulmonary pressure
___________________ is the pressure gradient required to produce flow in the conductive airways.
Transairway pressure
All modes of ventilation increase _______________________ during inspiration, by either decreasing pleural pressure or increasing alveolar pressure by increasing pressure at the upper airway.
Transpulmonary pressure
Which pressure is used to describe the pressure required to inflate the lungs during positive pressure ventilation?
Transrespiratory pressure
Frictional forces are the result of what two factors?
The resistance of the tissues and organs as they become displaced during breathing and the resistance to gas flow through the airways
Define elastance.
The tendency of a structure to return to its original form after being stretched or acted on by an outside force.
______________ is about the normal amount of pressure lost to airway resistance with a proper-sized endotracheal tube in place.
-5 cmH2O
What is the transairway pressure calculation?
Pta = PIP - P plat
An inspiratory time less than _____ time constants may result in incomplete delivery of the tidal volume.
Three