Can you live without blood? The reason is this - taking you closer to hyperbaric oxygen

Author: Yu Qiuhong, Chief Physician, Hyperbaric Oxygen Department, Beijing Tiantan Hospital, Capital Medical University

Reviewer: Xue Lianbi, Chief Physician of Hyperbaric Oxygen Department, Shenzhen Union Hospital, Huazhong University of Science and Technology

Everyone knows that blood is precious. For animals (including us humans), there is no life without blood. Blood transports nutrients and also transports oxygen needed for life to various important organs. Have you ever heard that animals can live without blood? Let me tell you slowly.

1. Bloodless Life

A Dutch scholar once conducted an experiment. He drew blood from a piglet and replaced it with saline and colloidal solution, which reduced the piglet's hemoglobin (Hb) and left it with almost no blood cells. Under normal circumstances, it would definitely die, but the piglet was placed in an oxygen chamber and pressurized to 3 atmospheres (absolute atmospheric pressure: ATA), equivalent to the pressure at a depth of 20 meters underwater. The piglet breathed pure oxygen in a high-pressure environment and survived without showing any abnormalities. After 45 minutes, the blood was transfused back and the piglet was decompressed and left the chamber. The piglet was still alive and well. This was the "Bloodless Life" that caused a sensation at the time. The method mentioned in it was hyperbaric oxygen (HBO) therapy. Since then, HBO therapy has quickly entered the public eye.

2.What is hyperbaric oxygen therapy?

HBO therapy is a treatment that involves inhaling high partial pressure oxygen in a high pressure environment. According to the Hyperbaric Society, the HBO treatment pressure should be greater than 1.4 ATA. In clinical practice, we use 1.5 to 3.0 ATA for treatment, and 2.0 ATA is commonly used, depending on the treatment population and purpose, which is equivalent to the atmospheric pressure at a depth of 10 meters underwater. Each treatment lasts 60 to 120 minutes, and requires a process of increasing pressure, stabilizing oxygen inhalation, and reducing pressure.

3. Principles of Hyperbaric Oxygen Therapy

Under normal circumstances, different cellular components in the blood have different functions. Hemoglobin (Hb) in red blood cells combines with oxygen and transports it throughout the body, while the amount of oxygen dissolved in the blood (or liquid) is very small. It is like in a "river" composed of blood, most of the oxygen drifts away on the "boat" of Hb, and only a small part swims in the blood.

Figure 1 Copyright image, no permission to reprint

When a person is anemic, he will experience symptoms such as palpitations, shortness of breath, and lack of energy. This is because the "boat" he can take - Hb - is reduced. At this time, even if the blood oxygen saturation is measured to be 100%, although the hemoglobin is fully loaded for transportation, after all, the transportation capacity is insufficient and oxygen is not sufficient. When a cerebral infarction occurs, the patient's blood vessels are blocked or extremely narrow, and there is no blood supply at the distal end of the blocked blood vessels, which cannot allow Hb to pass through, and the oxygen swimming over is minimal. The brain tissue cells supplied by this part of the blood vessels cannot get enough oxygen, resulting in symptoms such as hemiplegia and speech difficulties. At this time, the most urgent emergency measure is to quickly restore blood flow through thrombolysis. We may have heard of thrombolysis, which is to reopen the blocked blood vessels and allow blood to continue to circulate, and the patient's symptoms can be greatly improved. But everyone knows that thrombolysis has a time window, and it cannot be used after a certain time.

Can oxygen be transported without blood? This is almost an impossible task under normal pressure, but it can be done under high pressure, especially during HBO treatment. As the external pressure increases, the amount of oxygen dissolved in the liquid increases, that is, the amount of oxygen for swimming increases greatly. Oxygen is supplied directly to tissue cells through the body fluid circulation in a physiological way. This is the most basic principle of HBO treatment and the basis for the survival of bloodless life. Under high pressure, the amount of oxygen dissolved in the liquid increases. In addition to blood, cerebrospinal fluid, aqueous humor, and even most of the cells are liquid components, so HBO can supply oxygen directly to tissues, especially hypoxic tissues, improve hypoxia, and promote tissue recovery. From the figure below, you can see that the amount of oxygen dissolved increases greatly after inhaling pure oxygen under different pressures.

Figure 2 Copyright image, no permission to reprint

The "pig" experiment mentioned above used 3ATA, and the dissolved oxygen could reach 6.5 ml. Under normal circumstances, based on 15 grams of hemoglobin, 5.2 ml of oxygen is consumed per 100 ml of blood. Therefore, even if there is no blood at 3ATA, the dissolved oxygen is enough to supply life needs, so "bloodless life" can continue.

In addition, during HBO treatment, the oxygen in the blood diffuses quickly and far outside the blood vessels. What is the effect? ​​When many diseases occur, the blood vessels are edematous, just like the wall is thickened, the normal pressure oxygen cannot escape, and there is no oxygen supply outside the wall. However, high pressure oxygen can penetrate the thick blood vessel wall and supply oxygen in time. Together with the dissolved oxygen, it can improve hypoxia. Moreover, it can enhance the deformability of red blood cells. The capillaries are relatively thin, and the red blood cells usually queue up to pass through. When the surrounding is edematous, the capillaries are compressed and deformed, and the lumen becomes thinner. At this time, on the one hand, the deformability of red blood cells is enhanced, and on the other hand, even if the red blood cells cannot pass through, as long as the liquid component of the blood can pass through, the dissolved oxygen can be smoothly supplied to the hypoxic edematous tissue. HBO can help establish collateral circulation. Our blood vessels are like tree branches, and oxygen will diffuse in all directions, so improving hypoxia is three-dimensional and all-round. HBO has many other effects, which will not be repeated here.

3. Indications for hyperbaric oxygen therapy

Although HBO has a wide range of effects, there are also absolute contraindications, namely, untreated tension pneumothorax and pneumocephalus. There are also some relative contraindications, such as uncontrolled epilepsy, high fever, hypertension, colds, etc. Why is it called relative? That is to say, it is not absolutely prohibited. In clinical practice, Chinese medicine practitioners may choose to use it after finding the cause and weighing the pros and cons according to the patient's condition. For example, the patient is in a coma due to carbon monoxide poisoning, but has high blood pressure. If HBO treatment is performed only after the blood pressure drops, the secondary injury may be more serious, and high blood pressure may also be related to poisoning. We will weigh the pros and cons, observe the condition, and use drugs reasonably while performing HBO.

As for the indications of HBO, it can be said that except for contraindications, all diseases based on ischemia and hypoxia can be applied. It can treat emergencies, such as carbon monoxide poisoning, acute brain resuscitation, promotion of critical flap survival, limb swelling caused by post-traumatic compartment syndrome, persistent wounds, gas gangrene and other infectious diseases. Tiantan Hospital features neurology, and we often treat many patients after neurosurgery, including those with trauma, tumors, cerebral aneurysm embolization, and cerebral vascular stenosis stents. Acute application can improve patients' coma, hemiplegia, aphasia, memory loss and other symptoms. Of course, in addition to acute treatment, HBO can also be used for ischemic hypoxic encephalopathy, stroke, orthopedic rehabilitation, and sudden deafness. But we must weigh the pros and cons and do what we can.

Of course, HBO can sometimes treat the cause of the disease, that is, to remove the cause of the disease, such as gas embolism and decompression sickness. As long as the pressure is increased, the volume of gas will decrease, and the gas embolism will become smaller, and the disease can be cured without oxygen. Sometimes it can only improve symptoms. For example, in the case of anemia, although HBO cannot increase the number of red blood cells, it can immediately improve the symptoms caused by hypoxia caused by anemia. On the basis of treating the primary disease and coordinating drug treatment, adding HBO can achieve twice the result with half the effort. Especially for patients with religious beliefs who cannot receive blood transfusions or take medication, it is not an exaggeration to say that it is "immortal".

In short, for various diseases caused by ischemia and hypoxia, there is a good trick - HBO. Leave the specific treatment indications to professionals, which may bring you unexpected surprises.