Increase blood oxygen content, increase blood oxygen partial pressure
Blood oxygen transport pathways: 1. Directly combine with hemoglobin to form oxyhemoglobin. for chemical dissolution. Every 100mL of blood contains about 14g of hemoglobin, which can bind about 19mL of oxygen under normal pressure (the oxygen saturation of hemoglobin binding is 97%), which is the main way of oxygen transport under normal pressure. 2. Dissolution in physical state: Under normal pressure, only 0.3mL of oxygen is dissolved in every 100mL of blood. Although the amount of oxygen transported in this way is small, it is first used by the tissue, and then the oxygen in the oxyhemoglobin is separated from the hemoglobin, dissolved in the blood, diffused into the blood of the tissue, and used by the tissue cells.

Under high pressure, the oxygen saturation of hemoglobin reaches 100% rapidly and can no longer bind oxygen. The oxygen dissolved in the physical state in the plasma increases continuously with the rise of the oxygen partial pressure. At 3 standard atmospheric pressure (ATA), the amount of dissolved oxygen in a physical state can reach 6.6mL, which is 22 times that of breathing air at normal pressure. That is to say, under 3ATA, only physically dissolved oxygen can fully provide oxygen supply to tissue cells.

Therefore, hyperbaric oxygen is used to treat hemoglobin loss or inactivation diseases, such as carbon monoxide poisoning, blood loss and other degenerative hemoglobinopathy, and can be used as an emergency measure to compensate for the decrease in blood flow.


Increase blood oxygen diffusion and improve tissue oxygen reserve
According to the laws of gas physics, the speed of gas diffusion is proportional to the pressure difference of the gas. The greater the pressure difference, the faster the mass, the larger the diffusion volume and the longer the diffusion distance. During hyperbaric oxygen therapy, the partial pressure of alveolar oxygen increases significantly, the amount of oxygen diffused into the arterial blood in the alveoli increases compared with normal pressure, and the oxygen content in arterial blood also increases significantly. The amount of diffusion from arterial capillaries to tissue cells also increases, the diffusion distance increases, and the oxygen reserves of various tissues also increase greatly. Under normal pressure, when breathing air, the diffusion radius of oxygen in the capillaries in the body is 30um; under 3ATA oxygen, the effective diffusion radius can be increased to 100um, which is more than three times the effective radius of inhaling air under normal pressure. The oxygen content and partial pressure of oxygen in tissue cells and body fluids also increase.

Therefore, hyperbaric oxygen is used to treat diseases that increase the diffusion distance caused by tissue edema: such as cerebral edema and pulmonary edema, and it can also be used to treat diseases that cause oxygen supply disorders due to capillary damage or vascular obstruction: cerebral thrombosis, burns, and extruded limbs Injury, post-traumatic blood circulation disorder, etc.

Constrict blood vessels throughout the body
Under hyperbaric oxygen, blood oxygen tension increases, blood vessels automatically adjust, resulting in vascular smooth muscle contraction. In brain tissue, when cerebral blood vessels constrict, cerebral blood flow decreases; but due to the increase of combined oxygen and physical dissolved oxygen in the blood, the partial pressure of oxygen in brain tissue and cerebrospinal fluid actually increases compared with normal pressure. Therefore, hyperbaric oxygen is very effective in the rescue treatment of cerebral hypoxia and cerebral edema. It improves the hypoxic state of the brain tissue by increasing the blood oxygen content and blood oxygen partial pressure. At the same time, due to cerebral vasoconstriction, cerebral blood flow decreases, cerebral edema and intracranial pressure are reduced, thereby breaking the vicious cycle of cerebral hypoxia-cerebral edema-increased intracranial pressure.

In particular, under hyperbaric oxygen, the blood flow of the carotid artery system decreased, while the blood flow of the vertebral artery increased instead. Therefore, the partial pressure of oxygen in the brainstem of the reticular activating system is relatively increased, which is beneficial to the awakening of comatose patients and the maintenance of vital function activities.

Promotes fibroblast proliferation and collagen production
When the local tissue oxygen partial pressure is 5-10mmHg, the proliferation of fibroblasts and the formation of collagen fibers are inhibited. Under hyperbaric oxygen, blood oxygen partial pressure and extracellular fluid oxygen partial pressure increase, stimulate vascular fibroblast division activity and collagen fiber formation, promote the formation of new blood vessels, accelerate the establishment of collateral circulation, effectively correct and improve hypoxic state of the tissue. The aerobic metabolism is strong, and enough adenosine triphosphate is produced, which is beneficial to the synthesis of protein and promotes the growth of fresh granulation and epithelium.

Therefore, hyperbaric oxygen is used to treat various diseases such as skin grafting, replantation of severed fingers (toes), cerebral thrombosis, intractable ulcers, aseptic osteonecrosis, chronic osteomyelitis, and poor fracture healing.

Inhibit the growth of anaerobic bacteria
Anaerobic bacteria can only grow in an oxygen-free or low oxygen partial pressure environment. When the oxygen partial pressure is 250mmHg, the exotoxin production of Clostridium aerogenes is also inhibited. Therefore, under 2.5-3.0 ATA oxygen, all anaerobic bacteria cannot grow and reproduce in the body.
Therefore, hyperbaric oxygen has special effects in the treatment of gas gangrene and tetanus.

Eliminate air bubbles in the body
The pressure of a gas is inversely proportional to its volume. Under hyperbaric oxygen, the gas bubbles are compressed. At 2ATA, the bubble shrinks by 1/2; under 3ATA oxygen, the bubble shrinks to 1/3. Blood supply to blood vessels blocked by air bubbles is restored. At the same time, the oxygen in the blood replaces the nitrogen in the air bubbles and utilizes them, and the air bubbles disappear quickly. Therefore, hyperbaric oxygen has a special effect in the treatment of embolism and decompression sickness.