Proning: Its anatomical basis and effect on oxygen saturation in COVID patients

Proning is the process of turning the patient from their supine (lying on their back) position to lying on their abdomen. It is a medically accepted position for improving oxygenation while breathing. Respiration in supine position, compresses the posterior surface of the lung preventing normal distension of the alveoli. This results in suboptimal oxygenation of the blood circulating in the lobes of the lung, particularly lower lobes. Lowered V/Q ratio from these regions of the lung contributes to the venous admixture. In the prone position, the heart with its pericardial chamber, occupies anterior dependent portion of the mediastinum, resulting in better expansion of the alveoli. This leads to improved V/Q ratio from these regions and lowers the physiological shunt effect on the oxygen saturation.