Respiratory Cycle plus DSA by Rogers

Question 1

What is intrapleural pressure?

Answer 1

Ppl The pressure everywhere in the thorax besides the lumens of blood vessels, lymph or airways.
-5 cm H2O at rest & -8 cm H2O during inspiration.

Question 2

What is alveolar pressure?

Answer 2

The pressure inside the alveoli. At rest, pressure is equal to the atmospheric pressure outside the chest cavity (0 cm H2O). At the end of inspiration, Pa is -1 cm H2O due to the increase in alveolar size

Question 3

What is tidal volume?

Answer 3

Amount of air inspired or expired in a single breath. At rest normal is Vt = 500 ml. Exercise can increase this volume

Question 4

What is alveolar ventilation?

Answer 4

Valv = Vt -Vds. Tidal volume minus dead space volume. (350 ml)
V(dot)alv = Valv x frequency. Alveolar ventilation is now alveolar ventilation multiplied by frequency.

Question 5

What is transpulmonary pressure?

Answer 5

Ptp = Palv - Ppl

5 cm H2O at rest. The pressure difference between alveolar pressure and intrapleural pressure.

Question 6

Boyle’s Law

Answer 6

P1V1 = P2V2
Increase in lung volume, pressure decreases - air enters
decrease in lung volume, pressure increases - air exits

Question 7

Anatomic dead space

Answer 7

Person’s weight = ml of Vds

Space in respiratory system other than alveoli where there is is air but no blood for gas exchange.

Question 8

Alveolar dead space

Answer 8

Alveoli receive air but no blood. Normal is ~0

Question 9

Physiological dead space

Answer 9

Basically alveolar dead space.

Phys. DS = Vt x (PaCO2 - PeCO2)/PaCO2

Question 10

Calculating compliance

Answer 10

(change in volume)/(change in pressure). It is highest during normal breathing range, Vt.

Question 11

Calculating compliance

Answer 11

(change in volume)/(change in pressure). It is highest during normal breathing range, Vt. Opposite of elasticity.

Question 12

Impacts in compliance

Answer 12

Fibrosis and obesity lowers compliance - Shallower Vt and higher frequency.
Age increases compliance as elasticity decreases from loss of elastin and increased collagen.
Emphysema increases compliance as it destroys alveolar septal tissues that opposed lung expansion.

Question 13

Residual volume

Answer 13

Volume of air that is left after exhalation. Cannot be forced out during exhalation. (1200ml)

Question 14

Inspiratory Reserve volume (IRV)

Answer 14

Additional volume that can be inhaled greater than tidal volume (3000 mL)

Question 15

Expiratory Reserve volume (ERV)

Answer 15

Additional volume that can be exhaled greater than tidal volume. DOES NOT INCLUDE RESIDUAL VOL (1100-1200mL)

Question 16

Total lung capacity (TLC)

Answer 16

Maximal volume to which lungs can be expanded with greatest effort. (5800-6000ml)
TLC = IC + FRC =VC +RV = ERV +RV + IRV +Vt

Question 17

Functional residual capacity (FRC)

Answer 17

Helps to prevent lung collapse following normal expiration. Reduces workload and dilutes toxic inhaled gases (2300-2400)

Question 18

Vital Capacity

Answer 18

VC = IRV + Vt + ERV. Air that can be maximally inspired following a maximal expiration (4600-4700 ml)

Question 19

Inspiratory capacity

Answer 19

IC = Vt + IRV Capacity of air that can be maximally inspired following a normal exhale (3500 ml)

Question 20

Lung vol influencers

Answer 20

Body size, age, posture, sex, ethnicity, obesity, pulmonary diseases

Question 21

Helium dilution

Answer 21

Inhalation of known [He], which is insoluble in blood, from a known volume. The change in concentration

Question 22

Body Plethysmography

Answer 22

Change in pressure in closed box as one breathes against shutter. Proportionally box changes in opposite direction of change in lung pressure. Determines FRC

Question 23

Nitrogen washout tech.

Answer 23

Determines FRC. Evaluates respiration of 100% O2 through one-way valve and collection of all expired gas. Tot vol of all gas expire determined and multiplied by % of N2 in mixed expired air (80%)