Pul 2 - Lung vol and Pulm Circ

Question 1

What is the inspiratory reserve volume (IRV)?

Answer 1

The additional air that can be forcibly inhaled after the inspiration of a normal tidal volume.

Question 2

What is the expiratory reserve volume (ERV)?

Answer 2

The additional air that can be forcibly exhaled after the expiration of a normal volume.

Question 3

What is the inspiratory capacity (IC)?

Answer 3

It is tidal volume plus inspiratory reserve volume.

TV + IRV = IC.

Question 4

What is the vital capacity?

Answer 4

It is the inspiratory capacity plus the expiratory capacity.

IC + ERV : VC

Remember that Inspiratory capacity is Tidal volume + inspiratory reserve volume.

Question 5

What is residual volume?

Answer 5

It is the amount of air left in you after you exhale as much as you can.

Question 6

What is functional residual capacity?

Answer 6

It is expiratory reserve volume plus residual volume.

ERV + RV: FRC

Question 7

What is total lung capacity (TLC)?

Answer 7

All the volume that can be taken, exhaled, and left in the system.

IRV + TV + ERV + RV: TLC
or
IC + FRC: TLC
or
VC + RV: TLC

Question 8

What is the air that isn’t participating in gas exchanged called and what are it’s components?

Answer 8

Physiological dead space.

1. Anatomical dead space: Air in the airways.
2. Function dead space: capable of gas exchange, but no gas exchange occurs (apices of the lung during relaxed breathing); cannot be directly measured but can be calculated using dead space equation.

Question 9

What is the equation for dead space?

Answer 9

Vd = Vt x (PaCO2 -PECO2)/ PaCO2.

Vd: Dead space
Vt: Tidal volume
PaCO2: Partial CO2 of arterial blood.
PECO2: PCO2 expired air.

Question 10

What is tidal volume?

Answer 10

The amount of air that is moved in and out of the lungs during normal, relaxed respiration.

Question 11

What happens in the lungs in a decrease in alveolar oxygen?

Answer 11

Local vasoconstriction.

Question 12

What does effect does COPD have on the pulmonary vasculature?

Answer 12

Low alveolar oxygen causes chronic vasoconstriction, which causes pulmonary hypertension. Sustained pulmonary hypertension causes cor pulmonale (lung disease that causes heart failure).

Question 13

What are the 2 factors that can limit gas exchange?

Answer 13

1. Perfusion. (Under normal circumstances, transfer of O2 is limited by perfusion).
2. Diffusion.

Question 14

What causes bronchoconstriction of an airway?

Answer 14

1. Anaphylaxis.
2. Bronchospasm.
3. Asthma.
4. Parasympathetic stimulation.

Question 15

How would sympathetic stimulation of the beta 2 receptors affect the radius of the airway?

Answer 15

It will increase the radius, decreasing resistance.

Question 16

How can we lower the viscosity/density of air going through the airway?

Answer 16

Have the patient breath a specific mixture of helium and oxygen to lower air viscosity.

Question 17

What is the normal pulmonary artery pressure?

Answer 17

It is 10 to 15 mmHg.

Question 18

What is the number that defines pulmonary hypertension?

Answer 18

Pulmonary artery pressure of 25 mmHg or above at rest. Or greater than or equal to 35 during excercise.

Question 19

What is another name for primary pulmonary hypertension and what are the causes?

Answer 19

Also known as idiopathic pulmonary arterial hypertension, caused by:

1. Abnormalities in BMPR2: Bone Morphogenetic Protein Receptor II: normally this gene prevents proliferation of vascular smooth muscle; mutation of this gene leads to reduced vessel radius, increased resistance, and increased pulmonary arterial pressure.
2. Associated with HIV and Kaposi sarcoma (HHV-8).
3. More common in women, average age is 36.

Question 20

What is the cause of secondary pulmonary hypertension?

Answer 20

1. Chronic lung disease: COPD, pulmonary fibrosis.
2. Mitral stenosis.
3. Recurrent thromboemboli.
4. Autoimmune disease.
5. Left-to-Right shutns (VSD).
6. Sleep apnea or high altitude: Hypoxic vasoconstriction.

Question 21

What is the treatment for pulmonary hypertension?

Answer 21

1. Bosentan or Ambrisentan: Both end in -sentan, the competitively antagonize endothelian-1 receptors, decreasing pulmonary resistance.
2. Iloprost or Epoprostenol (Prostaglandin analogue): They relax smooth muscle.
3. Sildenafil (Revatio; not viagra in Pul HTN): fosfodiaesterase inhibitor.
4. Nifedipine: dihydropyridine calcium channel blocker.
   3.

Question 22

If a lung collapses, what happens to the intrathoracic volume?

Answer 22

When this happens, the chest wall is allowed to expand, unnaposed by the lungs, increasing intrathoracic volume.

Question 23

What gene mutation can cause primary pulmonary hypertension?

Answer 23

BMPR 2 mutation.

Question 24

What is the mechanism of action of Bosentan?

Answer 24

Antagonist at the endothelin-1 receptor.