Witwer Nightingale Lower Resp Tract Flashcards
A person at rest breathes about ____ liters of air per minute – Tidal Volume X Breaths per minute
6+
Systemic Arterial and Pulmonary Venous Blood
•Partial pressure O2 (PaO2) in systemic arterial blood?
•Partial pressure CO2 (PaCO2) in arterial blood?
100mmHg
40mmHg
-Systemic Venous and Pulmonary Arterial Blood
•Partial pressure of O2 (PvO2) in systemic venous blood?
•Partial pressure of CO2 (PvCO2) in systemic venous blood?
40mmHg
46mmg
With altitude, the Barometric Pressure __?
decreases
Partial Pressure of O2 (PiO2) in dry inspired air (760 x .21 =)160 mmHg
Partial Pressure of O2 in alveoli= 100mmHg
why?
Some is converted to water vapor in lungs
Dissolved O2 contributes to the partial pressure of O2 in blood, but O2 bound to hemoglobin does not. O2 bound to hemoglobin contributes to the ____ _____.
O2 saturation
Diffusion is a 1. _______ process.
It requires a 2. ______ gradient and is affected by
3.______ _____ _____.
What diseases will decrease the alveolar surface area??
Diffusion is affected by 4.______ the molecules must diffuse across.
What diseases will thicken the alveolar/pulmonary membranes??
Diffusion depends on the amount of capillary blood flow= 5.______.
- passive
- pressure
- emphysema - membrane surface area
- edema - distance
- perfusion
Partial pressure gradient of O2 & CO2 across the alveolar-capillary membrane?
O2= 60mmHg
CO2=6mmHg
CO2 diffuses ____x and CO diffuses _____x faster than O2
CO2= 20x
CO=200x
Remember the “driving force” for gas exchange is the pressure differential between the partial pressure of the gas in the alveoli and the partial pressure of the _____ gas in the blood (not gas bound within red cells).
soluble
Under normal conditions, Oxygen diffusion from the alveolar air into the pulmonary capillary blood is _______ limited, ie the ability of the gas to diffuse depends on the amount of ______ ______ through the capillary adjacent to the alveolus.
- perfusion
2. blood flow
Under some abnormal conditions, however, this diffusion capacity decreases and Oxygen diffusion becomes _____ limited.
Diffusion
2 conditions that decrease diffusion capacity & examples of each
increase in alveolar capillary membrane thickness (pulm fiborisi & pulm edema)
decrease in effective area for diffusion
(Atelectasis, emphysema, ARDS, pulm emboli)
when is CO2 perfusion limited?
NL and abnormal states
Note ideally the Arterial/Alveolar Gradient for oxygen is: Normally, the Gradient is: what happends w/age?
100-100=0
NL 5-10
increase 1mmHg per decade
Hypoxemia secondary to a _____ or _______cause will _______the A-a gradient by _______ mmHg.
pulmonary or cardiac
increase
30mmHg+
Hypoxemia secondary to an extrapulmonarycause will have a ______ A-a gradient.
normal
Name the defect:
Alveoli perfused, but O2 not delivered to alveoli – ie_____
A-a gradient?
Ventilation defect
atelectasis
increases
Name the defect:
Alveoli ventilated but no perfusion of the alveoli – i.e ______
A-a gradient?
Perfusion defect
pulm embolism
increases
Name the defect:
O2 cannot diffuse through alveolar-capillary interface – 3 examples?
A-a gradient?
Diffusion Defect
Interstitial fibrosis, pulm edema, pneumonia
increases
Name the defect:
Tetralogy of Fallot, Transposition of Great Vessels, Truncus Arteriosus
A-a gradient?
Right to Left Cardiac Shunts
increases
Name the defect:
barbiturates, brain injury
A-a gradient?
Depresion of medullary respiratory center
A-a gradient NL
Name the defect:
Epiglottitis, Croup, Laryngeal edema
A-a gradient?
Upper airway obstruction
A-a gradient NL
Name the defect:
Paralyzed diaphragm, ALS, spinal cord injury
A-a gradient?
Muscular dysfunction
A-a gradient NL
