Introduction

Overview of hyperbaric oxygen therapy

Chronic wounds and medical conditions can both be treated with hyperbaric oxygen therapy (HBO). Normal air comprises of 21% oxygen, but in hyperbaric oxygen therapy, 100% oxygen is delivered. When oxygen is delivered via a pressurised chamber, it is two to three times more concentrated than ambient air, allowing a patient’s lungs to absorb and utilise more of it. Oxygen is necessary for the body's tissues to repair and fight illness. Hyperbaric oxygen therapy (HBOT) is another name for HBO therapy.¹

This therapy has been used as a primary or adjunct treatment for infections, ischemia, chronic wounds, and inflammation.²

Incorporating higher concentrations of oxygen helps fight bacteria. Furthermore, it triggers the production of compounds known as growth factors and stem cells, which stimulate healing.³

The U.S. Food and Drug Administration (FDA) has approved hyperbaric oxygen treatment to help treat the following disorders:¹ gas gangrene, carbon monoxide poisoning, cyanide poisoning, and crush injuries.⁴ Hyperbaric oxygen treatment (HBOT), which promotes cell and tissue repair, appears to speed up the healing process of exercise-related muscle injuries.⁵

Hyperbaric oxygen therapy involves two main kinds of chambers:

• Monoplace chambers - A monoplace chamber is constructed for only one person
• Multi-place chamber - serves two or more patients who require the same treatment session for a particular disease. Compared to a monoplace chamber, the multi-place chamber lowers treatment costs and is preferred in the majority of medical scenarios⁷

Mechanism of action of hyperbaric oxygen therapy

Hyperoxygenation

The "Haldane'' effect, which is the outcome of the oxygen–haemoglobin reaction on CO2 transport, is named after the fact that oxygen and haemoglobin combine to form a stronger acid. 

First, haemoglobin has less of a tendency to react with CO2 to produce carboxyhaemoglobin in an acidic environment. This causes a large portion of the CO2 that is in this form in the blood to be displaced. 

Secondly, because haemoglobin is more acidic, it releases additional H+ ions, which combine with bicarbonate ions to form carbonic acid. This carbonic acid then separates into water and CO2, which are released from the blood into the alveoli.

Vasoconstriction

Increased oxygen levels cause vasoconstriction, which lowers blood flow without significantly affecting tissue oxygenation. HBO is used to treat thermal burns and regulate compartment pressures in crush injuries.⁸

Bubble size reduction

The volume of gas bubbles in the blood is reduced by 2-3 times at high air pressure compared to normal air pressure. The blood plasma is saturated with oxygen at high oxygen intake (100%). It is the main mechanism in the treatment of arterial gas embolism and decompression sickness.⁸

Antimicrobial effects of HBOT

The hyperoxic conditions produced by HBOT can cause a number of physiological and biochemical changes that enhance the antibacterial effects of standard treatment.⁹ HBOT is generally recognised to be effective when used as a primary or supplemental therapy for infections. The bactericidal and bacteriostatic effects of HBOT can affect both aerobic and primarily anaerobic bacteria.¹⁰

Role of HBOT in inflammatory conditions

Effects of HBOT in chronic wounds

Excessive matrix degradation results in tissue loss for chronic wounds. Proteolytic enzymes, mainly matrix metalloproteinases (MMPs), are overexpressed in this process. Numbered 1 through 19, MMPs are a complicated collection of enzymes. They are further separated into categories of collagenases, gelatinases, stromelysins, and membrane-type MMPs based on the substrate. Tissue inhibitors of MMPs (TIMPs) are naturally occurring inhibitors of MMP function.¹² HBOT was demonstrated to decrease MMP1, 2, and 8 expression and activity starting on day 7 of treatment in a rat chronic wound model. MMP9 showed reductions as early as day 3 of HBOT. Moreover, TIMP2 expression improved starting on day three of therapy. Histological examination of the injured tissue revealed MMPs predominantly in fibroblasts and macrophages.¹³ HBOT has been demonstrated to boost fibroblast proliferation in human dermal fibroblast cells; however, this effect is observed starting on day 7 of therapy, not at the start of the treatment. The synthesis of VEGF, the basal growth factor of fibroblasts, and transforming growth factor β1 is further increased by HBOT.¹²

HBOT in inflammatory bowel disease

The medical term for a chronic inflammatory gastrointestinal problem that encompasses Crohn's disease, ulcerative colitis, and other conditions is "inflammatory bowel disease" (IBD). Weight loss, diarrhoea, bloody stools, and inflammation of the intestinal mucosa are all signs of inflammatory bowel disease (IBD). Neutrophils and macrophages intensify this inflammation by producing cytokines, proteolytic enzymes, and free radicals that cause ulceration and inflammation.¹⁴ Because IBD is linked to a weakened immune response, HBOT can fortify immunity by boosting oxygen supply to the tissues and cells. Given this, a thorough evaluation of 19 trials was conducted to examine how HBOT affected IBD; 13 of these studies focused on Crohn's disease, and six on ulcerative colitis. Results indicate that immunomodulators, anti-inflammatory drugs, and corticosteroids were administered to study participants in every study. HBOT was found to have a beneficial and significant influence on both kinds of IBD, as evidenced by the improvement observed in around 78% of patients (31/40) with Crohn's disease and all patients (39/39) with ulcerative colitis in six investigations.¹⁵

Complications of hyperbaric oxygen therapy

For a variety of conditions, hyperbaric oxygen therapy (HBOT) usually serves as a safe treatment. There are a few negative side effects. Data on adverse reactions were gathered between 2009 and 2010 from patients receiving treatment in monoplace chambers, and the side effects rates were estimated to be approximately 0.4%. Roughly half of all adverse reactions can be characterised as ear pain, and 25% as confinement anxiety. The two types of side effects of hyperbaric oxygen therapy are pressure-related side effects and oxygen-related side effects. Barotrauma is a consequence of pressure that can occur in any closed, air-filled cavity such as the teeth, sinuses, ears, lungs and colon. 

Summary

Many conditions, including IBD, chronic wounds and musculoskeletal problems, respond well to HBOT. By delivering 100% oxygen under high pressure, hyperbaric oxygen therapy enhances tissue oxygenation, speeds up the wound healing process and possesses antimicrobial qualities.

The use of HBOT for treating various inflammatory disorders has been licensed by the FDA. In various clinical trials, it has shown effectiveness in the treatment of inflammatory disorders. Mainly for those having trauma, chronic wounds or IBD. 

HBOT offers the potential to reduce inflammation, speed up the healing process and increase the results for treatment. All things considered, HBOT is a useful therapeutic approach with several uses in the treatment of inflammatory diseases, providing patients with a secure and efficient course of care. To fully investigate its potential and maximise its application in clinical practice, more investigation and clinical trials are necessary.