Respiratory Physiology I Flashcards
What is the Difference in PO2 and PCO2 in the mixed venous blood going into the lung? Saturation?
PO2 - 40 mmHg
PCO2 46 mmHg
75 %
What is the Difference in PO2 and PCO2 in the arterialized blood going away from the lung? Saturation?
PO2 - 100 mmHg
PCO2 - 46 mmHg
97.4%
What are the major controls for ventilation?
- Central Chemoreceptors for pH and CO2
- Peripheral O2, CO2, and pH
- Higher brain centers
Where are peripheral chemoreceptors located?
- Carotid body off of arterial carotid
- Aortic bodies
- Subclavian artery
What is normal Total Ventilation? Alveolar Ventilation?
Qt: 6 L/min
QA: 4.2 L/min
How physiological dead space calculated?
VDCO2 = TV(PACO2 - PECO2) / PACP2
TV - Tidal Volume
PACO2 - Alveolar Partial pressure CO2
PECO2 - Expired Partial pressure CO2
How is the effective driving force between the alveolus, capillary, and interstitium calculated?
What is the effective driving force from the pulmonary capillary to the intrapleural space?
dPeff = TMP - σ Δπ
σ - Reflection Coefficient
π - Oncotic Pressure
8 mmHg
Describe the balance of fluid needed in the intrapleural space. What are the results of imbalance?
Too little fluid —> Rubbing and pain
Too much fluid —> layers come apart (Pleural effusion) —> Intersitial edema —> Alveolar flooding
What is normal Tidal volume? Normal anatomic dead space? How does anatomical dead space relate to weight?
TV = 500 ml
ADS = 150 ml
Or
1 ml / Lb
What is FRC?
Functional reverse capacity
FRC = ERV (Expiratory reserve volume) + RV (Residual Volume)
What is vital capacity?
VC = IC (Inspiratory capacitance0 + ERV (Expiratory Reserve Volume)
“Everything - RV”
“Everything that you can breath in or out”
How is helium dilution used to measure FRC and RV? How is FRC calculated? RV?
- Helium spirometer used and valve is closed.
- At end of tidal expiration/ beginning of FRC equilibrium, valves is removed.
Initial He = Final He
He lungs + He Spiro = He in combined
0 + 0.10*3000ml = 0.5(FRC + 3000)
FRC = 3000
RV = FRC - ERV (ERV calculated by standard spirometry)
How is FRC measured by Plethysmography?
- Person put into airtight box
- Measure airway Pressure and Box pressure
- At end of inspiration , Person breathes in and volume of lung and pressure changes
- Use Boyles law to calculate FRC or initial volume
PV = P’ (V + dV)
dV calculated by Change in pressure Where dP (Measured) = k*dV
Differentiate Use for He dilution vs Body Plethysmography.
He dilution —> Communicating Gas Volume; Lung gas that can mix with the breathing mixture
Plethysmography —> Total Gas Volume; Gas that is or is not in communication with alveoli
How is alveolar pressure calculated?
Palm = Prec + Pe
Or
Alveolar = Recoil + External (Intrapleural or intrathroacic)
What is Body Surface pressure?
Pressure acting on the body outside of atmospheric.
Ex. Swimming in water, car on chest
How is trans-lung Pressure calculated?
Ptl = Palv - Ppl = Prec
Or
= Palv - Pth
What is transwall pressure?
Ppl - Pbs
How is compliance calculated?
- dV/dP (transmural pressure)
What happens tp 2/3 of the work used in inspiration?
Elastic - Recovered by the lungs via expiration
How is 1/3 of work in inspiration lost?
4/5 —> Resistance
1/5 —> Overcoming tissue viscosity
What does the chest wall elastic force do? When is Chest force = 0?
Tends to expand lung for most lung volumes
Approximately 70% TLC
What are the primary characteristics of RDS?
- Low surfactant
- increased surface tension
- Muscular fatigue to reopen Alveoli
Differentiate Valsalva and muller maneuvers. Associated dangers?
Valvalva —> Forced Expration against closed glottis
- Lg (-) Pressure causes large transmural pressure —> Hemorrhage
Muller- Forced Inspiration against closed glottis
Large (+) pressure
- > Lung rupture
- > Aortic +BP, - HR
- > Vena Cava -VR
