Respiratory Dynamics: Resistance to Airflow (PK3)

Question 1

What is airflow resistance defined as?

Answer 1

Pressure difference required for a given flow

Question 2

Normal airflow resistance

Answer 2

0.2kPa.L.s-1

Question 3

What is the most frequent cause of ventilatory impairment?

Answer 3

Increased resistance to breathing

Question 4

What is the difference between the start and end distending pressure on a static graph representing?

Answer 4

Work required to stretch the lungs (or compliance)

Question 5

What is the difference between the start and end distending pressure on a dynamic graph representing?

Answer 5

Work required to stretch the lungs AND work required to move the air itself (dynamic resistance)

Question 6

What percentage of dynamic resistance is friction in the airways?

Answer 6

80-90%

Question 7

What percentage of dynamic resistance is lung tissue friction?

Answer 7

10-20%

Question 8

Equation linking flow, change in pressure and resistance

Answer 8

Flow = ΔPressure / Resistance

Question 9

Poiseuille’s equation

Answer 9

Flow = ΔPressure x (π x radius4) / (8 x length x viscosity)

Question 10

What is resistance proportional to?

Answer 10

1 / Radius4

Question 11

Where is most airway resistance found?

Answer 11

Upper airways (larynx/pharynx + large airways)