One‐lung anaesthesia-Pathophysiology, Conduct and Techniques

One lung ventilation (OLV) or one lung anaesthesia means separation of the two lungs and each lung functioning independently by preparation of the airway. It continues to remain as one of the challenging and skilled techniques of anesthesia practice. The need for isolating one lung from the other for different surgical procedures on the lungs, mediastinum or great vessels is well established. A variety of techniques have been developed to isolate one lung and considerable clinical experience has been gained over last two decades. Knowledge about the physiology of ventilation and perfusion at different positions and during one lung ventilation has made one lung anaesthesia a safe technique in the majority of patients. However in some, severe hypoxemia may occur. This review focuses on the different physiological and anatomical variables causing hypoxia and measures to counteract it.