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Describe with diagrams the flow–volume loops in: Healthy adult Restrictive lung disease Obstructive lung disease — 2020 June Draw a diagram to show the various lung volumes and capacities. Describe the spirometry features of obstructive and restrictive pulmonary disorders. — 2021 May Describe the pulmonary function test. What are the findings in obstructive and restrictive lung disease? — 2022 May, Diploma Write a short note on flow–volume loops in airway obstruction. — 2023 June 2. Ventilation–perfusion relationship Describe ventilation/perfusion ratio briefly with a diagram and the factors affecting the ventilation–perfusion ratio.

Reading File
This set of questions covers two major respiratory physiology topics:
  1. Spirometry, lung volumes, capacities, and flow-volume loops
    • Normal flow-volume loop
    • Obstructive lung disease, including asthma/COPD and upper-airway obstruction patterns
    • Restrictive lung disease
    • Lung-volume spirogram: TV, IRV, ERV, RV, VC, FRC, TLC
    • Pulmonary-function-test interpretation: FEV₁, FVC, FEV₁/FVC, TLC, RV, DLCO
  2. Ventilation-perfusion (V/Q) relationship
    • Definition and normal regional V/Q variation
    • V/Q diagram from apex to base of the lung
    • Physiological dead space, shunt, low V/Q and high V/Q states
    • Factors affecting V/Q ratio and consequences for oxygenation and carbon dioxide
High-yield overview:
  • Obstructive disease: expiratory airflow is limited. FEV₁ falls disproportionately more than FVC, so FEV₁/FVC decreases. The expiratory limb of the flow-volume loop is concave or “scooped out.” TLC and RV are commonly increased because of air trapping/hyperinflation.
  • Restrictive disease: lung expansion and total lung size are reduced. FEV₁ and FVC both fall proportionally, so FEV₁/FVC is normal or increased. The loop has a near-normal shape but is smaller and narrower. TLC is reduced, which confirms restriction.
  • Normal V/Q: whole-lung V/Q is about 0.8. Both ventilation and perfusion increase from apex to base, but perfusion increases more, so V/Q is high at the apex and low at the base.
Which should I develop first in full exam-note format with labelled diagrams: (1) flow-volume loops and PFTs or (2) V/Q relationship?
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