What occurs with the dependent lung when a patient is placed in the lateral decubitus position?

When a patient is placed in a lateral decubitus position, the dependent lung, which is the lung that is lower in relation to gravity, typically receives increased perfusion due to the effects of gravity on blood flow. Blood naturally flows preferentially to the lung that is dependent because gravity causes more blood to pool in that region, which enhances perfusion. However, the ventilation of the dependent lung may be compromised due to the position of the thorax and potential alterations in lung mechanics, leading to poor ventilation. This scenario is commonly observed in patients, especially those with conditions affecting lung function or those who are sedated.

Therefore, the statement identifying that the dependent lung receives increased perfusion but is poorly ventilated accurately reflects the physiological changes occurring in this position. The increased perfusion can enhance gas exchange under certain conditions but may not be efficient if the ventilation does not match the increase in blood flow.