Respiratory4

Question 1

Normally, pulmonary circulation is a ___-resistance, ____-compliance system.

Answer 1

Low-Resistance

High-Compliance

Question 2

A decrease in PaCO2 causes a vasoconstriction that shifts blood away from _______ ventilated regions of the lung to _______ ventilated regions.

Answer 2

Poorly ventilated to Well-ventilated

Question 3

What is a serious complication of pulmonary hypertension?

Answer 3

Cor Pulmonale and subsequent Right Ventricular Heart failure

*Jugular venous distension, Edema, Hepatomegaly

Question 4

What is the equation for lung diffusion?

How does Emphysema & Pulmonary fibrosis affect it?

Answer 4

Vgas = A/T x Dk(P1-P2)

A = Area (DEcreased in Emphysema)
T = Thickness (INcreased in pulmonary fibrosis)
Dk(P1-P2) = differences in partial pressures

Question 5

What is normal pulmonary artery pressure?

Answer 5

10-14 mmHg

Question 6

What does pulmonary hypertension result in? (3)

*> 25mmHg or > 35 mmHg during exercise

Answer 6

Arteriosclerosis
Medial hypertrophy
Intimal fibrosis

Question 7

What is Primary Pulmonary Hypertension caused by?

Answer 7

Inactivating Mutation in the BMPR2 gene

*poor prognosis

Question 8

What is the normal function of BMPR2gene?

Answer 8

Inhibits vascular smooth muscle proliferation

Question 9

What are the causes of Secondary Pulmonary Hypertension? (6)

Answer 9

• COPD
• Destruction of lung parenchyma
• MItral Stenosis
• INcreased Resistance –> Increased P
• Recurrent Thromboemboli
• Decreased Cross-sect area of vasc bed
• Autoimmue disease (ie systemic sclerosis)
• Inflamm -> Intimal fibrosis -> Medial hypertrophy
• Left-to-Right shunt
• INcreased shear stress -> Endothelial injury
• Sleep Apnea or Living at High altitudes
• Hypoxic vasoconstriction

Question 10

What is the clinical course of Severe Respiratory Distress?

Answer 10

Cyanosis & RVH

Death from decompensated cor pulmonale

Question 11

What is the equation for pulmonary vascular resistance (PVR)?

Answer 11

PVR = (P pulm artery - P L atrium)/CO

P pulm artery = pressure in pulmonary artery
P L atrium = pulmonary Wedge pressure

Question 12

O2 content =

Answer 12

(O2 binding capacity x % saturation) + dissolved O2

Question 13

Normally 1 g Hb can bind ____ mL O2

Answer 13

1.34

Question 14

Normal Hb amount in blood is ___ g/dL

Answer 14

15 g/dL

Question 15

Cyanosis results when deoxygenated Hb > ___ g/dL

Answer 15

5 g/dL

Question 16

O2 binding capacity =

Answer 16

20.1 mL O2/dL

Question 17

O2 content of arterial blood DEcreases as Hb falls, but what happens to O2 saturation and arterial PO2?

Answer 17

They don’t change

Question 18

Oxygen delivery to tissues =

Answer 18

Cardiac Output x Oxygen content of blood

Question 19

What is the Alveolar Gas Equation?

Answer 19

PAO2 = PIO2 - (PaCO2/R)

PAO2 = alveolar PO2 (mmHg)
PIO2 = PO2 in inspired air (mmHg)
PaCO2 = arterial PCO2 (mmHg)
R = respiratory quotient = CO2 produced/O2 consumed

Question 20

Alveolar gas can normally be approximated by what equation?

Answer 20

PAO2 = 150 - PaCO2 / 0.8

Question 21

A-a gradient = PAO2 - PaO2 =

Answer 21

10-15 mmHg

Question 22

What causes an INcrease in the A-a gradient?

Answer 22

Hypoxemia d/t:

• Shunting
• V/Q mismatch
• Fibrosis (impairs diffusion)

Question 23

What causes Hypoxemia (DEcreased PaO2) w/ a Normal A-a gradient?

Answer 23

High altitude

Hypoventilation

Question 24

What are causes of Hypoxia (DEcreased O2 delivery to tissue)?

Answer 24

DEcreased Cardiac Output
Hypoxemia
Anemia
CO poisoning

Question 25

Ischemia (loss of blood flow) leads to what?

Answer 25

Impeded arterial flow

Reduced venous drainage