Lecture 23: Review and Clinical Cases

Question 1

Unit for pressure of gases?

Answer 1

cm of H2O

Question 2

Unit for pressure of fluids?

Answer 2

mmHg

Question 3

What would happen if one’s vitality exceed one’s vital capacity?

Answer 3

Death

Question 4

Does the inspiratory capacity have a clinical significance?

Answer 4

NOPE

Question 5

Most important lung capacity?

Answer 5

Functional residual capacity: where we end and start our breathing when we are breathing normally

Question 6

Notation of partial pressures in the pulmonary arteries?

Answer 6

Pv

Question 7

Notation of partial pressures in the pulmonary veins?

Answer 7

Pa

Question 8

What does anatomic dead space mean with regards to the alveolar membrane?

Answer 8

It does not exist

Question 9

What is the PiO2 of moist inspired gas of a climber on the summit of Mt. Everest assuming barometric pressure is 247 mmHg? What will be his PAO2 assuming his PaCO2 is 32 mmHg? What will be his PAO2 if he hyperventilates to a PaCO2 of 24?

Answer 9

PiO2 = (247 - 47) x 0.21 = 42 mmHg

PAO2 = 42 - 32/0.8 = 2 mmHg (not compatible with life)

PAO2 = 42 - 24/0.8 = 12 mmHg (not great either)

Question 10

A patient is breathing room air in the ER with a respiratory rate of 10 and a TV of 500 mL

PAO2 = 100 mmHg
PACO2 = 40 mmHg 

He then increases his respiratory rate to 20 but keeps his VT = 500 mL

What is his new PACO2? PAO2?

Answer 10

RR doubled, so PACO2 is halved to 20 mmHg

PAO2 = 150 - 20/0.8 = 125 mmHg

Question 11

Equation for VD/VT ratio?

Answer 11

= PACO2-PECO2/PACO2

PACO2 = alveolar CO2
PECO2 = expired CO2