Why Lying Face-Down Helps Relieve Coronavirus Symptoms

How ‘proning’ Covid-19 patients helps them breathe

Image: Wellcome Library, London. Wellcome Images images@wellcome.ac.uk/CC BY 4.0

Thousands of patients suffering from severe cases of Covid-19 are experiencing a simple treatment in hospitals throughout the world: They are being placed face-down on their hospital bed in a practice known as proning. This change in position is often enough to improve lung functionality and reduce the impact of respiratory distress caused by Covid-19.

The Lungs and Gravity

The lungs are remarkably complex in functionality. As the primary interface for gas exchange in the body, the lungs are a dynamic organ that responds to minute changes in the internal and external environments to maximize oxygen transfer and carbon dioxide removal.

When a person breathes in, air is pulled through the airways into a network of microscopic sacs called alveoli. Waiting on the other side of a thin barrier within millions of capillaries are red blood cells lined up ready to receive the incoming oxygen.

Based on the demand, position, and health of the lungs, this network of blood vessels dilate and constrict to maximize gas transfer — all under the orchestration of hormone and nerve signals. In one breath, the lungs saturate the blood in the pulmonary system with oxygen to be transferred throughout the body to meet metabolic demand.

For all their elegance and delicacy, the lungs are also subject to some crude forces.

The lungs are positioned within the thoracic cage, but are not technically attached to anything other than the airways and blood vessels that supply them. When you inspire (breathe in), muscles that expand the thoracic cavity — the diaphragm and accessory muscles surrounding the ribs — pull the chest wall away from the lungs.

Between the lung tissue itself and the inner wall of the chest is an enclosed space called the pleural cavity. When the chest wall draws away from the lungs, the pressure in the pleural cavity (intrapleural pressure) drops to the point where it is less than the pressure inside the alveoli (intra-alveolar pressure), which forces the lung tissue to expand as if being sucked toward the chest…