Physiology of the lateral position and one-lung ventilation

The first part of this article reviews the distribution of ventilation (V) and perfusion (Q) during the supine and the lateral decubitus position. The changes in the V/Q during the lateral position with and without paralysis are discussed. The second part evaluates the degree of transpulmonary shunt during one lung ventilation (OLV) and the role of hypoxic pulmonary vasoconstriction in maintaining arterial oxygenation. Finally, the influence and the use of nitric oxide during OLV is reviewed.