Chapter 4: Respiratory Physio Flashcards
Tidal Volume
Volume of air inspired or expired in a single breath.
Inspiratory Reserve Volume
The max amount of air you can Inspire ABOVE the tidal volume
Expiratory Reserve VOlume
The amount of air that can be expired below Tidal Volume
Residual Volume
Volume left in lung after Expirtory Reserve Volume
NOTE: Cannot be measured by Spirometry
Anatomic Dead Space
Volume of the conducting airways (150 mL)
physiologic dead space
Volume of the Lungs that does not participate in gas exchange
In normal lungs it is equal to the Anatomic Dead Space
physiologic dead space (Equation)
Vd = Vt x ((PAco2 - PEco2)/ (PAco2))
Minute Ventilation
Tidal Volume x (Breaths/Min)
Alveolar Ventilation
(Tidal Volume - Dead Space ) x Breaths/Min
Essentially, the air that actually reaches the alveolus)
Inspiratory Capacity
Tidal Volume + Inspiratory Reserve Volume
Functional Residual Capacity
Expiratory Reserve Volume + Residual Volume
NOTE: Cannot Be Measured by Spirometry (Residual Volume is not measurable unless the patient is dead)
Vital Capacity
Inspiratory Capacity (IRV + TV) + Expiratory Reserve Volume
Volume of air that can be forcible expired after a maximal inspiration.
Total Lung Capacity
The entire volume of the lung
NOTE: Cannot Be measured by Spirometry since it contains the Residual volume
FEV1
Forced Expiratory Velocity
The amount of air that can be expelled form the lungs in the first second of a forced expiration
FEV1/FVC = .8 !
FVC = Forced Vital Capacity (Inspiratory Capacity + ERV)
FEV1 In Obstructive Diseases
Asthma and Emphysema . Can get air in but you cannot get it out, thus FEV1 is diminished
FEV1/FVC = Less than .8
FEV1 in REstrictive Lung Disease
Fibrosis
Cannot get Air In but can get it out
FEV1 is increased
FEV1/FVC = Greater than .8 (usually around .9)
Artificially higher than normal
Inspiration
Contration of the diaphragm, pushes the abdominal contents down and ribs are lifted up and out
Negative pressure is increased, air comes into lungs.
External Intercostal and Accessory Breathing muscles
used during exercise (not during normal relaxed breathing)
Muscles of expiration
Psych… in normal breathing this is a passive process
Only used during times of need : Internal Intercostals and Abdominals
Compliance
C = dV/dP
The ability to distend. In the face of changing volume, highly compliant vessels distend without large increases in pressure. (Pressure is Transmural Pressure)
The more elastic your lung, the more compliant it is
Slope of the Pressure-Volume Curve
Transmural Pressure
Alvolar - Intrapleural Pressure
When pressure outside the lungs (intrapleural) is negative, the lungs expand (we typically have a negative intrapleural pressure so, according to the equation this will lead to an expansion in the lung)
Transmural Should always be positive unless you have a rupture in the pleural space leading to an increased intrapleural pressure which will cause atalectasis.
What occurs to the compliance of the lungs in a patient with Emphysema ?
The compliance is increased (incredibly), thus the tendency to collapse is decreased since the lung can expand farther.
A new, higher FRC will occur (FRC is the state at which the expanding force of the chest wall and the collapsing force of the lung are equal so there is net equilibrium)
A higher FRC shows that a higher airway pressure is needed for the collapsing pressure of the lung to equal the expanding pressure of the Chest wall. (FRC is higher because you can’t get the air you take in out. bigger RV)
As stated in a previous card, The FEV1 is decreased in emphysema and asthma (due to the decreased tendency of the lung to collapse with the higher compliance seen in these diseases)
I know this was a long card, mainly did it for myself to see if i remembered this crap
What occurs to compliance in a patient with Fibrosis ( Restrictive lung disease)
The lungs tendency to collapse is increased due to decreased compliance
With this you will see a new, lower FRC to balance out the forces of expansion from the chest wall and collapse form the lung.
FRC is smaller since you can expel a larger proportion of the air you take in (intake is also restricted in restrictive disease, so it looks like the RV is small)
What is the cause of Surface tension in the alveoli ?
Interactions between liquid molecules lining the alveoli