Resp 3 - Ventilation Flashcards
(30 cards)
What is TLC?
Total Lung Capacity (TLC) = EVERYTHING combined
When you inspire all the way in and fill your lungs up as much as possible, the volume of air in the lungs is the TLC
What is VC?
Vital Capacity (VC) = how much air is within the confines of what we are able to inspire and expire i.e. TLC - RV
What is FRC?
Functional Residual Capacity (FRC) = the volume of air in the lungs when the outwards recoil of the rib cage and the inward recoil of the lungs are in equilibrium
i.e. ERV + RV
It is the volume of air remaining in the lungs at the end of a tidal breath.
What is IC?
Inspiratory Capacity = how much extra air you can take in on top of the FRC
i.e. TV + IRV
What are the 4 main volumes?
TV
ERV
IRV
RV
What are the 4 main capacities?
FRC
IC
VC
TLC
What is IRV?
Inspiratory Reserve Volume
= amount of volume in reserve if you want to breathe more
Measure when taking big breath in - from the top of TV to the max.
What is ERV?
Expiratory Reserve Volume
When taking a max expiration from minimum TV to the peak of expiration
What is RV?
Residual Volume
Default amount of air that is in the lungs - cannot get rid of it
Not routinely measured/clinically important
What is TV?
Tidal Volume
Usually nasal
oscillates between 300-500 mL of air
= air going in and out to meet metabolic need of the body.
usually measured at rest. Exercise increases TV.
What are the two components of the chest-wall?
Independent Lung
Independent rib cage and muscles
Describe how the pleural cavity allows the chest wall and the lungs to move in unison.
The pleural cavity has a fixed volume and is at negative pressure. This means that when the chest wall expands, the lung gets pulled with it. (they are not physically attached)
What factors affect lung volumes and capacities?
Body size, sex, fitness (innate), disease, age
What unit is commonly used when describing lung pressures?
Unin: cm H20
What are the three main lung pressures involved in respiratory mechanics? Define them.
Transmural Pressure = pressure across a tissue or several tissues
Transpulmonary Pressure = difference between alveolar and intrapleural pressure
Transrespiratory Pressure = tells us the direction of airflow in the airways - most important. If positive –> expiration
Give two examples of positive pressure breathing.
CPR and Ventilators
Normal breathing = negative pressure breathing
What sign is the pressure during expiration? Inspiration?
Expiration –> Positive
Inspiration negative as chest wall expands. When air comes in, pressure comes back to 0 - start of expiration
This leads to a graph
What is the difference in alveolar pressure between the end of a tidal expiration and the end of tidal inspiration? Explain your answer.
NO DIFFERENCE - during inspiration, the thoracic cavity expands and so the alveoli expand and the pressure decreases. Air is drawn in to the alveoli and the pressure becomes the same as it was at the end of expiration.
Define Dead Space.
Parts of the airways and lungs that do not participate in gas exchange.
What are the two different types of dead space?
Anatomical Dead Space and Alveolar Dead Space
What is the normal physiological dead space of a healthy individual?
150 mL - physiological dead space is usually equivalent to anatomical dead space because normal healthy people don’t have alveolar dead space
State two reversible procedures that can change dead space.
Tracheostomy
Ventilators
Explain the chest wall relationship diagram (volume against pressure).
Expanding the chest wall to 6 L takes relatively little pressure because its natural tendency is to expand. Expanding the lungs to 6 L takes a lot more effort and pressure because its natural tendency is to recoil inwards. So the curves are different.
Curve of lung + curve of chest wall has sigmoid shape.
This indicates that around FRC (at the middle, when curve crosse y axis = FRC) it is easy to ventilate whereas emptying totally is hard.
What assessments are used to measure lung capacity?
Volume-time curve
Peak expiratory flow
Flow-volume loop
