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DMED 514 PULMO > 4 V/Q matching cont'd > Flashcards

Flashcards in 4 V/Q matching cont'd Deck (14)
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1
Q

A-aDO2 means? equal to?

A

A-a gradient, difference between alveolar and arteriolar oxygen –> PAO2 - PaO2 (alveoli minus arteriolar)

2
Q

A-aDO2 predicts? aka it tells us what?

A

degree of shunt by comparing the partial pressure of O2 in the (A) alveoli to that in the (a) artery –> how well the oxygen is moving from the alveoli to the arterial blood.

3
Q

physiologic shunt?

A

bronchial circulation comes off of aorta then drains into pulmonary veins –> mixing of deoxygenated blood from bronchial circulation and oxy blood from returning pulmonary circulation = shunt

4
Q

efficiency of oxygenation at top vs. bottom?

A

more efficient at top of lung, less at bottom –> but note that you are oxygenating a lot more blood at the bottom

5
Q

an anatomic shunt occurs when?

A

venous blood flows back to the circulation downstream from the lung - ie the bronchial circulation

6
Q

intrapulmonary shunt occurs when?

A

venous blood flows through an unventilated, lung, heart defects (like VSDs) or shunt channels in the lung (the ones that open at very high outputs)

7
Q

dead space is when V/Q = ? what does it mean? what air is this?

A

when V/Q - infinity so you have ventilation, no perfusion) –> air which is inhaled, but doesn’t take part in gas exchange either because it either remains in conducting airways, or reaches poorly perfused/not perfused alveoli

8
Q

benefits of dead space (4)

A

retain CO2 = bicarb buffer. inspired air brought to body temp (increases Hb affinity of O2). humidify air = improved mucus quality. particulate matter trapped in that mucus.

9
Q

pulmonary circulation is __flow, ___ pressure –> what is pulm vascular resistance? what happens if pressure very high?

A

high flow, low pressure so pulm. vascular resistance is very low. pulm vasculature relatively fragile, will leak water/blood into lung parenchyma if pulm. cap. pressure gets too high

10
Q

heavy exercise: what happens to pulm. venous oxygen? what happens to pulm artery pressure? result?

A

PvO2 lower b/c more peripheral extracting of O2. higher cardiac output = more blood flow through lungs, so higher pulm artery pressure. would get leakage into interstitium and cause pulm edema but we have shunt channels from arteries to veins

11
Q

effect of lung volume on PVR

A

low volumes, at RV: total PVR determined mostly by arterial R. going up to FRC, then TLC: capillary resistance account for most of total PVR

12
Q

relative contributions to PVR

A

small arterioles make the most contribution to resistance

13
Q

hypoxic vasoconstriction is what?

A

during hypoxia and hypercapnia, pulmonary circulation increases resistance to blood flow: helps shift blood flow away from areas which aren’t ventilated

14
Q

explanation behind high altitude pulmonary edema

A

less atm. pressure so partial pressure O2 decreases –> hypoxic vasoconstriction, but not uniform so the parts that don’t vasoconstrict get a lot more blood flow = edema