Pressure therapy is a medical intervention that uses physical force to apply controlled external or atmospheric pressure to the body for therapeutic purposes. This approach is a category of distinct therapies unified by manipulating pressure to elicit a physiological response. The goal is to influence biological processes at the cellular and fluid level, ranging from managing chronic swelling to promoting tissue healing. This concept has evolved from simple bandaging techniques to sophisticated computerized systems that deliver precise forces.
The Foundational Mechanism of External Pressure
External pressure applied to a limb or area alters the local balance of fluid exchange within the tissues. This intervention works by changing the hydrostatic pressure gradient, which drives fluid out of the capillaries and into the surrounding interstitial space. Applying compression increases the pressure outside the blood vessels, counteracting the internal hydrostatic pressure that causes fluid to leak into the tissue.
By raising the external tissue pressure, the overall pressure difference across the capillary wall is reduced, limiting the formation of new tissue fluid, or edema. This action also creates a pressure differential that pushes accumulated interstitial fluid back into the venous capillaries and, significantly, into the lymphatic vessels. The lymphatic system is stimulated to accelerate drainage from the compressed area toward the body’s core.
External pressure also manages scar tissue, such as hypertrophic scars that form after burns. Continuous, firm pressure reduces blood flow, leading to localized tissue hypoxia, or low oxygen levels. This hypoxic environment modulates the activity of fibroblasts, the cells responsible for producing collagen. By limiting excessive collagen production, pressure helps the scar mature, becoming flatter, softer, and less red over time.
Common Applications and Delivery Methods
The most frequent applications of external pressure therapy focus on managing conditions involving impaired fluid circulation. Lymphedema, chronic swelling caused by a damaged lymphatic system, is a primary target. Compression reduces the volume of the affected limb by preventing the accumulation of protein-rich fluid and encouraging its return to the central circulation.
Pressure is also widely used in the management of Chronic Venous Insufficiency (CVI). In CVI, damaged vein valves lead to blood pooling in the lower extremities. The external force compresses the veins, narrowing their diameter and improving the efficiency of the muscle pump to push blood back toward the heart. This action helps alleviate symptoms like leg pain, heaviness, and the development of varicose veins or venous ulcers.
For scar management, sustained pressure is applied to prevent or treat raised, dense hypertrophic scars following burn injuries. Specialized garments are custom-fitted to deliver a consistent force, typically 15 to 25 millimeters of mercury (mmHg). This regimen encourages the remodeling of collagen fibers into a more organized and pliable structure.
Pressure is delivered through two main methods: static and dynamic compression.
Static Compression
Static compression involves non-moving devices like elastic bandages, compression stockings, or custom-made pressure garments that maintain a constant level of force on the limb.
Dynamic Compression
Dynamic compression, often called Intermittent Pneumatic Compression (IPC), uses a pump to inflate and deflate air chambers within a sleeve that wraps around the limb. This sequential inflation creates a “milking” action, which systematically pushes fluid from the extremity toward the torso and is effective for augmenting lymphatic drainage.
Pressure Therapy through Systemic Hyperbaric Oxygen
A completely different form of pressure therapy is Hyperbaric Oxygen Therapy (HBOT). This involves the systemic application of high atmospheric pressure in a controlled setting. The patient breathes 100% oxygen inside a sealed chamber pressurized to a level greater than one atmosphere absolute (ATA), often between 2.0 and 3.0 ATA. The mechanism of action is based on physical gas laws, primarily Henry’s Law.
The increase in ambient pressure causes greater amounts of oxygen to physically dissolve into the blood plasma, independent of the oxygen carried by hemoglobin. Under normal conditions, plasma carries minimal oxygen, but in a hyperbaric environment, this dissolved oxygen level can increase significantly. This supersaturated plasma delivers oxygen to tissues with compromised blood flow, where red blood cells may be unable to penetrate.
HBOT treats specific conditions where oxygen deprivation contributes to tissue damage or delayed healing. FDA-approved uses include treating decompression sickness and carbon monoxide poisoning, where high pressure helps flush the toxic gas from the body. It is also used for specific types of non-healing wounds, severe infections, and radiation injury, where the increased oxygen supports natural healing and infection-fighting processes.