In the previous phase, the media articles such as “FDA reminds hyperbaric oxygen therapy is not a cure for all diseases” and “Hyperbaric oxygen therapy for cancer and diabetes is nonsense” were controversial and biased. In fact, this is a scientific and objective understanding of the problem of hyperbaric oxygen therapy, here it is necessary to elaborate, in order to correct the origin.
I. Hyperbaric medicine: an ancient and emerging discipline
The body inhales pure oxygen or high concentration of oxygen in an environment higher than one atmosphere (1.0 ATA) is called hyperbaric oxygen, and the method of using hyperbaric oxygen to treat diseases is hyperbaric oxygen therapy. Hyperbaric medicine is the study and solution of various physiological, pathological, biochemical and other medical problems related to hyperbaric oxygen or high air pressure. Hyperbaric medicine is an ancient and emerging discipline. The first application of hyperbaric oxygen to treat disease was a pioneering step by Valenzuela in 1887. However, the flourishing of hyperbaric medicine around the world actually began in the 1950s and 1960s, when Professor Boerema in the Netherlands carried out several breakthroughs: (1) direct cardiac surgery in a hyperbaric chamber, which prolonged the safe time of cardiac arrest and allowed complex surgery to be performed with ease; (2) the use of hyperbaric oxygen to treat diseases caused by anaerobic bacterial infections; (3) the conduct of “Life without blood” animal experiment: the experimental pigs were bled from the artery, while saline and colloid solution were injected from the vein, at which time there were almost no red blood cells in the blood, and the experimental pigs were placed in the 3.0 ATA hyperbaric chamber, and the pigs were still alive and the electrocardiogram was normal; after 15 minutes After 15 minutes, the blood was returned to the chamber and the pig was miraculously alive after decompression.
In 1963, the first International Conference on Hyperbaric Medicine (ICHM) was held in the Netherlands, organized and hosted by Prof. Boerema, marking the beginning of modern hyperbaric medicine. Professor Boerema is regarded as the founder of modern hyperbaric medicine.
In 1964, Professor Li Wenren built the first medical hyperbaric chamber in Fuzhou City, China, and successfully performed direct heart surgery in the chamber. Since then, Shanghai, Qingdao, Hangzhou, Nanjing, Beijing, Guangzhou and other places have built the medical hyperbaric oxygen chamber one after another. The 11th International Conference on Hyperbaric Medicine in 1993 and the 16th International Conference on Hyperbaric Medicine in 2008 were successfully held in China, which fully demonstrated the world-renowned achievements of hyperbaric medicine in China in the past decades. More than 600 units, more than 30,000 practitioners, are in the first place in the world, can be said to be a veritable great country of hyperbaric medicine.
Second, the basic mechanism of hyperbaric oxygen treatment disease
Clinical practice at home and abroad has confirmed that hyperbaric oxygen therapy has significant curative effect on certain diseases such as carbon monoxide poisoning, decompression sickness, anaerobic bacterial infection, ischemic-hypoxic encephalopathy, sudden deafness and so on. The basic mechanism is as follows.
1. Hyperbaric oxygen can raise the partial pressure of blood oxygen and increase the diffusion distance of oxygen
Compared with breathing air at atmospheric pressure (1.0 ATA), under 2.0 ATA hyperbaric environment, the partial pressure of blood oxygen of the body can be increased to about 14 times, and the blood oxygen content, tissue oxygen partial pressure and oxygen content can be increased accordingly. The diffusion distance of oxygen in the gray matter capillaries of the brain is 30 μm under normobaric pressure, which can be increased to 100 μm under 3.0 ATA hyperbaric oxygen. these effects are beneficial to improve or correct tissue hypoxia.
2. Mechanical effect of hyperbaric oxygen C shrinks the air bubbles in the body
In the hyperbaric environment, when the air pressure gradually increases, the bubble diameter will gradually decrease and the volume will also decrease accordingly. The partial pressure of oxygen outside the bubble is higher than the partial pressure of oxygen inside the bubble, and oxygen can displace the nitrogen inside the bubble, which accelerates the disappearance of the bubble. Therefore, hyperbaric oxygen has unique therapeutic effect on gas embolism and decompression disease.
3. Hyperbaric oxygen reduces tissue edema
Hyperbaric oxygen has a vasoconstrictive effect on the blood vessels of most vital organs. Hyperbaric oxygen can cause constriction of carotid artery, reduction of cerebral blood flow and decrease of vascular permeability. One study found that under 2.0 ATA of hyperbaric oxygen, cerebral blood flow is reduced by 21% and intracranial pressure is reduced by 36%, which can make cerebral edema be effectively controlled. Hyperbaric oxygen is also effective in reducing local tissue edema in conditions such as burns, crush injuries, and fascial intercompartmental syndrome. Although local tissue perfusion is reduced, the significant increase in partial pressure of blood oxygen is sufficient to improve tissue hypoxia, thus breaking the vicious cycle between tissue hypoxia and tissue edema.
4. Antibacterial effect of hyperbaric oxygen
Hyperbaric oxygen has an inhibitory effect on the growth and reproduction of anaerobic bacteria or some aerobic bacteria, and has a synergistic effect with some antibiotics such as aminoglycosides, increasing the antibacterial and bactericidal ability of antibiotics. The phagocytes’ ability of phagocytosis and bactericidal ability decreases in hypoxia. Hyperbaric oxygen therapy can improve the phagocytes’ ability of phagocytosis and bactericidal ability as well as the ability of phagocytosis of necrotic cells, and increase their anti-infection and foci elimination effects.
Changes of indications and contraindications of hyperbaric oxygen therapy at home and abroad
The comprehensive application of hyperbaric oxygen in clinical treatment began in the mid-1960s, and it has only been more than 40 years since then. With the development of the basic theory of hyperbaric medicine, oxygen chamber manufacturing technology and the accumulation of clinical experience, the indications and contraindications for hyperbaric oxygen therapy have been constantly revised and updated.
In the United States, for example, the indications for hyperbaric oxygen therapy first proposed by the United States Undersea Medical Society (UMS) in 1977 were 67 diseases, which were divided into 4 categories. In 1984, the indications were revised and divided into 2 categories: absolute indications and indications to be studied, with a total of 28 diseases. However, when it was revised again in 1986, it was changed to 3 categories of recognized indications, controversial indications and indications to be studied, totaling 34 diseases. Currently, the UHMS recommends the following 14 indications for hyperbaric oxygen therapy: gas embolism; carbon monoxide poisoning or combined cyanide poisoning; gas gangrene; crush injuries, fascial compartment syndrome and other acute traumatic ischemia; decompression sickness; central retinal artery obstruction, problematic wounds with difficult healing; severe anemia; intracranial abscess; soft tissue infection and necrosis; refractory osteomyelitis; radiological soft tissue injury, radiological osteonecrosis; skin and flap grafting; acute burns; sudden deafness (new UHMS recommendation, October 2011). The U.S. Food and Drug Administration (FDA) also recognizes these 14 diseases.
In China, the indications were formulated by the Chinese Specialty Committee of Hyperbaric Medicine in 1982, with 44 diseases. 2001, the indications proposed by the Sub-Committee of Hyperbaric Medicine of Chinese Medical Association were divided into 3 categories, with 74 diseases. 2004, the Sub-Committee of Hyperbaric Medicine of Chinese Medical Association revised the indications again, divided into 2 categories, acute indications and non-acute indications, with 61 diseases. Acute indications include the following 12 diseases: carbon monoxide poisoning and other harmful gas poisoning; gas gangrene, tetanus and other anaerobic bacterial infections; decompression sickness; gas embolism; acute cerebral dysfunction after cardiopulmonary resuscitation from various causes; adjuvant treatment of shock; cerebral edema; pulmonary edema (except cardiogenic pulmonary edema); extrusion syndrome; blood transport disorders after amputation (finger, toe) and skin transplantation; drugs and chemical poisoning; acute ischemic-hypoxic encephalopathy. There are 49 non-emergency indications, such as carbon monoxide poisoning and other toxic encephalopathies; sudden deafness; ischemic cerebrovascular disease; craniocerebral injury; diabetes mellitus and diabetic foot; malignant tumor (with radiotherapy or chemotherapy); spinal cord injury, etc.
From the point of view of the change of disease spectrum of indications for hyperbaric oxygen therapy, the change of disease spectrum in China and the United States are basically from complicated to simple. However, at present, there are far more types of diseases for which hyperbaric oxygen therapy is indicated in China than in the United States, which is related to the different social and economic factors (medical insurance, fees, etc.) in both countries. For example, in China hyperbaric oxygen is an inexpensive therapy, charging only a few tens of dollars for a treatment; while in Europe and the United States hyperbaric oxygen is a more expensive therapy, often charging hundreds of dollars for a treatment. In fact, in clinical work in the United States, the application of hyperbaric oxygen therapy is not limited to the 14 diseases recommended by the UHMS.
Contraindications to hyperbaric oxygen therapy are certain conditions that are not suitable for hyperbaric oxygen therapy, and their formulation has evolved with the times. 2004, the Chinese Medical Association’s Hyperbaric Medicine Branch proposed four absolute contraindications, namely, untreated pneumothorax, mediastinal emphysema; pulmonary maculopathy; active internal bleeding and hemorrhagic disease; tuberculous cavity formation and hemoptysis; 10 relative contraindications, namely, severe upper respiratory tract infection; severe Pulmonary emphysema; bronchiectasis; untreated malignant tumors, etc. These contraindications are more or less the same compared with those abroad. In our clinical work, we should pay attention to the dialectical view of the contraindications of hyperbaric oxygen therapy, to weigh the advantages and disadvantages, decisive decision.
Fourth, hyperbaric oxygen therapy: a special adjuvant treatment means
It is worth mentioning that when some people see the phrase “hyperbaric oxygen therapy for a certain disease”, they always think that they are discontinuing other therapies and using hyperbaric oxygen alone to treat the disease, but this is not true. It is rare that hyperbaric oxygen is used to treat a disease alone or as a primary treatment, but it is limited to acute carbon monoxide poisoning, gas embolism, decompression sickness and other diseases. In clinical practice, it is more common to use hyperbaric oxygen combination therapy, i.e., hyperbaric oxygen as an adjunctive therapy, combined with other therapies such as drugs or surgery to treat the disease. The advantage of hyperbaric oxygen therapy is that as a physical therapy, it can be used with other drugs or therapies without conflict and can have a synergistic effect.
For example, the hypoglycemic effect of hyperbaric oxygen in the treatment of diabetes was first reported by Kakhnovskii et al. in 1980 and has since been confirmed by a number of clinical studies in China and abroad. However, hyperbaric oxygen has been used as an adjunctive treatment in diabetes treatment protocols and has not replaced the use of dietary control and glucose-lowering drugs. The efficacy of applying hyperbaric oxygen to assist in the treatment of diabetic complications C diabetic foot is even more recognized worldwide.
Regarding malignant tumors (cancer), no clinician has ever used hyperbaric oxygen alone to treat them or said that hyperbaric oxygen can cure them. The appearance of malignant tumors in our indications for hyperbaric oxygen therapy is conditional, emphasizing the need to use it with therapies such as radiotherapy or chemotherapy. For example, the photochemical reaction of photodynamic therapy (PDT) depends on the presence of molecular oxygen, and the efficacy of PDT is limited by the lack of oxygen due to local vascular obstruction in tumor tissues; however, hyperbaric oxygen can increase the oxygen content in tumor tissues, which helps to enhance the efficacy of PDT. Some clinical and basic studies at home and abroad also show that radiotherapy and chemotherapy supplemented with hyperbaric oxygen therapy have better effects. Radioactive soft tissue injury and osteonecrosis after radiotherapy are also recognized by UHMS and FDA as indications for hyperbaric oxygen therapy.
Therefore, I wonder what is the basis of the statement “hyperbaric oxygen therapy for cancer and diabetes is nonsense”? If there is no sufficient basis, is this statement not “nonsense”?
As for autism in children, there is no special treatment and no indication for hyperbaric oxygen therapy. Some experts and scholars, represented by Professor Rossignol from the United States, have found that hyperbaric oxygen therapy has some effect on autism in children and explored a new way of treatment. Although the efficacy is still controversial, isn’t it worth encouraging such exploration and experimentation?
V. Safe hyperbaric oxygen therapy
When it comes to hyperbaric oxygen, some people tend to worry too much about its safety. The safety of hyperbaric oxygen therapy mainly lies in the elimination of fire hazards in the oxygen chamber and the control of possible side effects of hyperbaric oxygen.
According to the “Medical Oxygen Chamber Safety Management Regulations” issued by the State Bureau of Quality and Technical Supervision and the Ministry of Health in 1999, medical oxygen chambers include air pressurized chambers and oxygen pressurized chambers, and the design, manufacture, installation, use, management, periodic inspection and maintenance of oxygen chambers must comply with national regulations. 2007 “Letter from the Medical Secretary of the Ministry of Health on Stopping the Centralized Training of Medical Hyperbaric Chamber Practitioners” requires that the hyperbaric chamber In 2004, the “Medical Hyperbaric Oxygen Chamber Management and Application Standards” formulated by the Chinese Medical Association’s Hyperbaric Medicine Branch must be in line with the national regulations. Management and Application of Hyperbaric Oxygen Chamber” formulated by the Chinese Medical Association of Hyperbaric Medicine in 2004 has clear provisions on the operation procedures, treatment plans, management system and personnel responsibilities of hyperbaric oxygen chamber. Therefore, it can be said that the safety of hyperbaric oxygen therapy is guaranteed.
The side effects of hyperbaric oxygen therapy include air pressure injury, oxygen toxicity and decompression sickness, but the incidence is very low. The incidence of oxygen toxicity and decompression sickness is particularly rare. Barotrauma is commonly a middle ear barotrauma, and its prognosis is better. The article “FDA warns that hyperbaric oxygen therapy is not a cure-all” states that “hyperbaric oxygen therapy may cause minor injuries such as sinus pain, ear pressure, joint pain, and in severe cases, even paralysis and air embolism”, which is somewhat alarming. The cases of “paralysis and air embolism” caused by hyperbaric oxygen therapy are very rare and a very low probability event. The hyperbaric oxygen department of Beijing Chaoyang Hospital has applied hyperbaric oxygen therapy for more than one million times in the past 40 years, and there has not been a single case of “paralysis or air embolism”. If we do not talk about the probability of side effects, but talk about their seriousness, it is undoubtedly misleading and makes people choke on their food.
The development of hyperbaric medicine in China has taken the efforts and hardships of several generations and is not easy to come by. The task of hyperbaric medicine is to apply basic medicine, clinical medicine and related medical theories, continuously explore and master the mechanism of hyperbaric oxygen therapy, gradually improve the indications for hyperbaric oxygen therapy, and carefully master the contraindications. Every practitioner of hyperbaric medicine should be guided by the principles of evidence-based medicine, be prudent in their words and actions, which is the greatest care for the cause of hyperbaric medicine. Those claims that exaggerate or belittle hyperbaric oxygen therapy are unscientific and will not stand up to the test of practice.