Optimizing Lung Collapse During One-Lung Ventilation: Physiological Mechanisms and Clinical Strategies: A Narrative Review.

Effective thoracic surgery requires timely, predictable operative lung collapse. During one-lung ventilation (OLV), lung collapse is not merely a mechanical consequence of nonventilated lumen opening but a phase-dependent physiological process. Rapid phase I collapse is driven by elastic recoil and passive gas venting, whereas slower phase II collapse depends on residual alveolar gas absorption. Communication between the operative-side airway and the atmosphere before pleural opening may permit tidal gas movement, ambient air entrainment, and nitrogen re-entry during the closed-chest period, delaying subsequent absorption collapse. This narrative review reorganizes lung collapse strategies, including denitrogenation, operative-side airway occlusion, preemptive OLV, disconnection, bronchial suction, and the open-clamp airway technique, according to timing and physiological target. Before pleural opening, alveolar nitrogen should be reduced and ambient air entrainment prevented. Around the pleural opening, airway patency and brief suspension of positive-pressure ventilation may preserve elastic recoil venting. During OLV maintenance, re-clamping or limiting atmospheric communication may support residual gas absorption. This phase-based framework interprets recent clinical findings as interventions acting before, during, and after pleural opening. This may help clinicians select strategies according to the lung isolation device, oxygenation reserve, and surgical environment, although standardized endpoints and component-level validation remain necessary.