Lung lecture 3 Flashcards
Because lungs go downhill after age 20, what is considered normal PaO2 for elderly person?
~80 mmHg
Normal pulmonary interstitial pressure (Pis)
-8 mmHg
higher than systemic d/t lymphatics + negative thoracic pressure
Normal interstitial osmotic pressure (πis)
14mmHg (about double systemic)
Normal pulmonary capillary pressure (Pc)
7mmHg
Normal blood oncotic pressure (πpl)
28 mmHg
Increasing ventilation without increasing blood flow will _____ O2 and _____ CO2
increase O2 and decrease CO2
Increasing blood flow while keeping ventilation the same will _____ PAO2 and _____ PACO2
decrease O2, increase CO2
Normal minute ventilation (VT)
6L/min
Equation for minute ventilation
V̇T= VE= VT x BPM
tidal volume x breaths per min
Physiologic deadspace vs. alveolar dead space
P= both normal anatomical plus alveolar dead space
A= deadspace within the lung.
abnormal, airflow and gas to alveoli but no perfusion (ex = PE)
some decrease is expected with age
Overtime, positive pressure ventilation can ______ alveolar dead space
increase
Normal minute deadspace ventilation
1.8L/min
Normal Alveolar minute ventilation
4.2L/min
If alveolar deadspace increases, what is done to compensate
increase ventilation
Net filtration in pulmonary capillaries
1 mmHg
Which factors favor filtration
Pc, Pis, πis
which factors oppose filtration
blood oncotic pressure (πpl)
Pulmonary edema doesn’t become a problem until left atrial pressure reaches
~23 mmHg
What starling factor changes in ARDS, oxygen toxicity, and inhaled toxins that increase pulmonary edema
increased capillary permeability (Kf)
Which starling factor changes from inc. LA pressure from MI or mitral stenosis that increases pulmonary edema
increased capillary hydrostatic pressure (Pc)
Which starling factor changes due to rapid evacuation of pneumothorax or hemothorax that increases pulmonary edema
decreased interstitial hydrostatic pressure (Pis)
Which starling factor changes due to protein starvation, dilution of blood from IV fluids, proteinuria that increase pulmonary edema
decreased colloid osmotic pressure (πpl)
At FRC, pleural pressures are ____ at the base of the lung, and ____ at the apex of the lung
-1.5 cmH2O, -8.5 cmH2O
At FRC, the alveoli at the apex of the lung are ___% full
60%
At FRC, the alveoli at the base of the lung are ___% full
25%
At FRC, the alveoli at the base of the lung are _____ compliant than the alveoli at the apex
more
At RV, the alveoli at the base of the lung are _____ compliant than the alveoli at the apex
less
At RV, the alveoli at the base of the lung are ___% full
20%
At RV, the alveoli at the apex of the lung are ___% full
30%
At RV, pleural pressures are ____ at the base of the lung, and ____ at the apex of the lung
+4.8 cmH2O, -2.2 cmH2O
Lung compliance under GA is similar to when the lung volume is at ____
RV
Transpulmonary pressures at RV
apex: 2.2 cmH2O
base: -4.8 cmH2O
Transpulmonary pressures at FRC
apex: 8.5 cmH2O
base: 1.5 cmH2O
At RV, the lung fills up from ____ to ____ during inspiration
top to bottom
Are lungs more compliant during inspiration or expiration?
Expiration
V/Q matching occurs because of what?
Pleural pressure gradient - more neg at top, more pos at base
Transpulmonary pressure higher at top and lower at base
Alveoli at the top of the lung are ____ than the alveoli at the base of the lung
larger - less compliant
Where are the 2 smooth muscles that change lung ventilation and perfusion?
- pulmonary BV smooth muscle upstream of capillaries
- airway smooth muscle
Lower alveolar PO2 causes upstream
vasoconstriction - hypoxic pulmonary vasoconstriction (HPV)
Increased alveolar PCO2 causes upstream
vasoconstriction
How do volatiles affect HPV? How is this mediated?
Turns off this compensatory mechanism - vasodilation
Supplemental oxygen
Why do airways constrict when PAO2 is high?
To prevent alveolar dead space ventilation
How do lung volumes change when supine?
FRC decreased to 2 L
ERV reduced and IRV expands
Basic spirometry can measure what?
Tidal volume, ERV, IRV, and vital capacity
