Syllabus · Current · V5 (2025) · Respiratory System

C6 · Ventilation-Perfusion (V/Q) Relationships

C6.i · V/Q Relationships & West Zones

Official V5 objective
Describe the concepts of global and regional ventilation and perfusion and: a. describe the factors that affect these concepts, b. describe the West's zones of the lung and explain the mechanisms responsible for them, c. explain V/Q matching and mismatching, d. explain the effect of V/Q mismatch on oxygen transfer and carbon dioxide elimination.
2 SAQ topics 4 SAQ appearances 7 VIVA stations

Written examination

SAQ history

4 appearances
V/Q Mismatch
3 exam appearances
Describe the effects of Ventilation/Perfusion (V/Q) inequality on the partial pressure of oxygen (PaO2) in arterial blood
48%
Describe the effects of V/Q inequality on the partial pressure of oxygen (PaO2) and carbon dioxide (PaCO2) in arterial blood.
8%
Compare the effect on arterial blood carbon dioxide and oxygen levels of ventilation / perfusion inequalities.
West Zones
1 exam appearance
Describe the ventilation / perfusion (V/Q) relationships in the upright lung according to West’s zones (40%). Explain the physiological mechanisms responsible for these relationships (60%).
47%

Oral examination

VIVA history

7 stations

Sources: objective text from the relevant CICM syllabus; historical SAQ and VIVA wording from CICM examiner reports.