The physiology of one lung ventilation
Jul 30, 2026
One-lung ventilation (OLV) is one of the most fascinating examples of physiology in action. While it allows surgeons access to the thoracic cavity, it also creates a unique challenge for the anaesthesia team. Understanding what happens inside the lungs during OLV helps perianaesthesia nurses anticipate changes in oxygenation and appreciate why close monitoring is so important throughout the patient's perioperative journey.
During OLV, one lung is intentionally collapsed while the other continues to receive ventilation. Although blood flow continues to both lungs, ventilation is limited to only one, creating ventilation-perfusion (V/Q) mismatch. The body responds through hypoxic pulmonary vasoconstriction, redirecting blood away from the non-ventilated lung towards the ventilated lung. This protective mechanism reduces shunting and helps maintain oxygenation, although it cannot eliminate V/Q mismatch completely.
💙 One-lung ventilation increases physiological shunt because blood continues to flow through the non-ventilated lung.
💙 Hypoxic pulmonary vasoconstriction is the body's natural response to improve oxygenation by diverting blood towards ventilated alveoli.
💙 Oxygenation is influenced by patient positioning, lung pathology, ventilator settings and surgical factors.
💙 Both total intravenous anaesthesia and volatile anaesthesia may affect pulmonary physiology, but current evidence suggests neither demonstrates a clear overall advantage in preserving ventilation-perfusion matching.
For perianaesthesia nurses, understanding these physiological changes supports timely recognition of deteriorating oxygenation, informed communication with the anaesthetic team and confident postoperative assessment. Patients may remain vulnerable to impaired gas exchange following thoracic procedures, making ongoing respiratory observation essential.
A sound understanding of one-lung ventilation physiology allows perianaesthesia nurses to connect changes in monitoring with the underlying physiology, supporting safe, informed and patient-centred care.
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References
Campos, J.H. & Feider, A. (2021). Hypoxia During One-Lung Ventilation—A Review and Update. Journal of Cardiothoracic and Vascular Anesthesia.
Peyton, P.J., Marsh, H. & Thompson, B.R. (2019). Intravenous versus inhalational anaesthesia and lung ventilation-perfusion matching. Anaesthesia and Intensive Care.
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