Pulmonary circulation and hypoxic pulmonary vasoconstriction
Pressures, resistance and flow in the low-pressure pulmonary circulation, how hypoxic pulmonary vasoconstriction matches perfusion to ventilation, and why losing it (vasodilators, sepsis, cirrhosis) or triggering it globally (altitude, COPD, sleep-disordered breathing) explains common exam findings.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The pulmonary circulation takes the whole cardiac output at about one-sixth of systemic pressure: mPAP about 14 mmHg, PVR about 1 Wood unit.
- Resistance falls as flow rises because vessels are recruited and distended. PVR is lowest near functional residual capacity.
- Hypoxic pulmonary vasoconstriction (HPV) is unique to the lung. Systemic arterioles dilate in hypoxia; pulmonary arterioles constrict.
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Sources
- West's Respiratory Physiology: The Essentials (11th ed.)Wolters Kluwer (West and Luks, 2020), 2020
- 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertensionEuropean Society of Cardiology / European Respiratory Society (Eur Heart J 2022;43:3618-3731), 2022
- Definition, classification and diagnosis of pulmonary hypertension (7th World Symposium on Pulmonary Hypertension)European Respiratory Journal 2024;64:2401324, 2024
- Guyton and Hall Textbook of Medical Physiology (14th ed.)Elsevier (Hall and Hall, 2021), 2021
- Last updated
- 14 November 2026
What changed
- 14 November 2026 Personal emails, About story and Australian-style copy