The hyperbaric oxygenation ( HBO ; also hyperbaric oxygen therapy , HBO therapy ; English hyperbaric oxygen therapy , HBOT , HBO2 ) is a form of therapy in which 100%, medically pure oxygen under an increased ambient pressure (the air pressure is higher than normal atmospheric pressure ) is used for defined periods of time and intervals in patients through inhalation . This conventional medical and scientifically proven treatment method has its origins in diving medicine and is also used for carbon monoxide and smoke gas poisoning .
- Single person pressure chambers: Here the “chamber air” is also the treatment breathing gas (100% oxygen). There are also single-person chambers that work with normal air as chamber air. The oxygen is then supplied as in the multi-person chambers.
- Multi-person pressure chambers: In these, the chamber air does not consist of the breathing gas. This is supplied via separate breathing systems. Breathing 100% pure oxygen can be done in several ways:
The invention and application of hyperbaric oxygen therapy are based on several physical principles. Hyperbaric oxygen therapy is based on the physical laws of gas. Henry's gas law is of particular importance for the use of oxygen in excess pressure:
Solubility of gases in liquids
Henry's law of physics describes the solubility of gases in liquids. The amount of gas dissolved in a liquid increases proportionally with the pressure on the liquid in the system of gas and liquid. In concrete terms, this means that the higher the pressure, the more gas can be dissolved in a liquid.
- One example is the bottling of mineral water with the gas carbon dioxide (CO 2 ). In accordance with Henry's law, CO 2 is added to the water under overpressure and increasingly dissolved in the water. If the pressure above the liquid is reduced when the bottle is opened, the carbon dioxide escapes and the gas dissolved in the water under excess pressure bubbles out in the form of fizz. The solubility of the carbon dioxide in water decreases with the decrease in air pressure above the liquid through opening.
Transmission to living beings
Because blood is undoubtedly a liquid, Henry's law applies unreservedly. As part of hyperbaric oxygen therapy, the patient is treated with 100% pure oxygen, which, according to Henry, is enriched in the body fluids according to the pressure applied. In humans, oxygen is mainly transported by chemical bonding to the hemoglobin contained in red blood cells . The number of red blood cells, or more precisely the amount of hemoglobin, is therefore decisive for the oxygen transport capacity of the blood.
According to Henry, however, oxygen is - to a normally small extent - also in physically dissolved form in the blood and in all body fluids. The amount of the physically dissolved oxygen depends on the oxygen partial pressure in the breathing air . Since the red blood cells and the hemoglobin are already 95 to 100% full or saturated ( oxygen saturation ) with normal breathing air (21% oxygen) , an increase in the blood oxygen content via the oxygen bound to the hemoglobin is practically impossible. The increase in the proportion of oxygen (partial pressure) in the air we breathe from 21 to 100% (about five times) causes a proportional increase in the amount of oxygen dissolved in the blood. The oxygen partial pressure can be increased further by increasing the ambient pressure. If a person breathes pure oxygen in a pressure chamber at a pressure of, for example, 2.5 bar, approximately 20 times the amount of oxygen is dissolved in the blood. In relation to the total oxygen content in the blood, the increase effect is not great, but it is significant: This increases the possible diffusion path for oxygen in the capillary area (i.e. the path between blood vessel and cell) from normally 64 µm to 247 µm, which in the case of circulatory disorders and other conditions of oxygen deficiency Meaning is:
Oxygen partial pressure of the lungs at 21% oxygen (normal air) 150 mmHg Oxygen partial pressure in the lungs at 100% oxygen at 1 bar ambient pressure (normal pressure) 600 mmHg Oxygen partial pressure lungs with 100% oxygen at 2.5 bar ambient pressure (pressure chamber) 1800 mmHg Oxygen content of arterial blood at 100% oxygen and hemoglobin concentration of 15 g / dL 22.4 mL / dL - of which chemically bound to hemoglobin 20.3 mL / dL - of which physically dissolved in the plasma 2.1 mL / dL - Amount of dissolved oxygen at 3 bar overpressure in the pressure chamber 6.4 mL / dL
Pressure – volume relationship
This relationship is based on Boyle-Mariotte's law , which basically states that the volume (volume) of a gas decreases with increasing pressure. Or: with decreasing pressure, the volume (volume) increases. Conversely, it is also true that the pressure decreases with increasing volume or the pressure increases with decreasing volume.
- Under standard conditions, a balloon contains 1 liter of air. If you bring this balloon into a water depth of 10 meters, the same balloon contains only 500 milliliters (0.5 liters) of air without supplying or removing air. At the same time, the ambient pressure rose from 1.0135 bar (sea level) to 2.0 bar (about 10 meters water depth).
Partial pressure principle
This principle is based on the Law on the partial pressures of John Dalton . Dalton found that the total pressure of a gas mixture, such as the normal atmospheric air on earth, is composed of the partial pressures of the individual gases in the mixture.
- At sea level, air consists of around 78% nitrogen , around 21% oxygen and around 1% noble gases , carbon dioxide and other gases and has a pressure of around 1.0 bar . According to Dalton's law, the air pressure at sea level of 1.0 bar is therefore composed of:
- about 78% nitrogen = about 0.78 bar partial pressure of nitrogen
- about 21% oxygen = about 0.21 bar partial pressure of oxygen
- approx. 1% remaining gases = approx. 0.01 bar partial pressure of the remaining gases
Hyperbaric oxygen therapy is used worldwide for diseases in which a lack of oxygen is the cause of insufficient healing and the deficiency can be compensated for by the use of HBO. There are also some emergency illnesses in which oxygen is life-saving. The use of hyperbaric oxygen is based on scientific studies of varying quality. According to the criteria of evidence-based medicine, there are now numerous studies for various clinical pictures of the highest evidence class (1a). For other clinical pictures there are studies in class 1b and, moreover, extensive literature, which, as is common in medicine, reflects the wealth of experience in hyperbaric medicine. As a result, the HBO is recognized and financed by many national health systems around the world for expanding catalogs of indications. Nevertheless, the use of the HBO is controversial in Germany and other countries. This is due to several factors:
- For many indication areas that are still to be regarded as experimental, there are currently no high-quality studies according to the standards of evidence-based medicine (ideally: prospective , randomized, controlled , double-blind ).
- The structures of the HBO in the Federal Republic of Germany with predominantly privately owned institutions require financial necessities that are not helpful for a purely scientifically controlled acquisition of knowledge.
- The availability of facilities for HBO is limited. Consequently, establishing clinical research on patient groups is difficult (transport problems, scientific support from universities, etc.).
- The high costs of such a therapy due to the availability (24 hours) of technology and personnel do not have a beneficial effect on the conduct of studies (high financial investment necessary for uncertain results).
- Different ranges of indications have become established in the individual countries, despite consensus being reached on indication areas at national and supranational level.
- This results in some considerable differences in the reimbursement of the costs of HBO therapy
Patient education for treatment with HBO
With regard to the scope of the duty to inform, there is no difference between hyperbaric oxygen therapy and other medical measures (comprehensive duty to inform). This includes information about the situation regarding reimbursement (or non-reimbursement) by health insurance providers . The duty to inform is to be understood in accordance with the clinical picture to be treated in such a way that treatment alternatives are also listed. The treatment alternatives include the possibility of observation or no intervention (see also the spontaneous healing rate for the diseases tinnitus and sudden hearing loss ).
Applications for hyperbaric oxygen therapy
According to the recommendations of the medical scientific societies for hyperbaric oxygen therapy in Europe and worldwide - European Committee for Hyperbaric Medicine (ECHM), European Underwater and Baromedical Society (EUBS), Society for diving and hyperbaric medicine (GTÜM), Undersea and Hyperbaric Medical Society (UHMS) ) - Based on evidence-based scientific studies, the following indications arise:
Indications with an urgent recommendation for the use of HBO
- Clostridial myonecrosis / gas burn ¹ infection or other anaerobic infection
- Decompression sickness - diving accident¹
- Bone necrosis
- Carbon monoxide / cyanide / smoke gas poisoning ¹
- Air or gas embolism caused by diving accident or iatrogenic air embolism ¹
- necrotizing soft tissue infections
- Neuroblastoma - recurrence , stage IV¹
- Radionecrosis of bones and soft tissue
- Bridging acute blood loss if a blood transfusion is rejected , for example for religious reasons
- Diabetic foot syndrome
Indications with recommendation for the use of HBO
- Acute traumatic ischemia (crush injuries, compartment syndrome)
- Acute sudden hearing loss, pop trauma, acute noise damage, acute tinnitus with proven hair cell damage
- Selected problem wounds (wound healing disorders in diabetes mellitus ¹   ( diabetic foot syndrome ), arterial non-healing ulcers )
- Impaired graft (grafts and advancement flaps)
- Brain abscesses
- Bone marrow edema and aseptic bone necrosis     
- Side effects of radiation therapy with wounds or organ damage to the skin, bladder or rectum
- Osteomyelitis Chronic Refractory
- External otitis maligna
Further indications for the adjuvant use of HBO are currently being tested according to scientific standards. A recommendation for the HBO application is therefore made by the medical scientific societies z. Not yet.
As with all medical services, a “guarantee” of a successful improvement or cure is not possible. As a rule, the HBO is used adjuvant to the otherwise necessary treatment measures if these have not been sufficient for the treatment to be successful. The education in the hyperbaric center also explains the chances of success with HBO, alternative and conventional treatments.
Risks and Side Effects
As with any medical treatment, there are risks and side effects associated with using HBO. They are rare overall.
- Barotrauma of the eardrum : This side effect is common. It is mostly limited to a slight reddening of the eardrums, which heals by itself within 24 hours. In children (see frequency of otitis media ) the frequency of side effects is higher.
- Fire hazard in the pressure chamber: This applies in particular to the atmosphere with 100% oxygen in a single person pressure chamber. In multi-person pressure chambers, the risk is also increased, but in fact insignificant. Breathing takes place in an almost closed system, the chamber air consists of compressed air and in Germany monitoring of the oxygen content of the chamber air is mandatory (must be less than 23%). In the one-person pressure chambers with an atmosphere of 100% oxygen, which are not common in Germany, there is a considerable risk of fire in the presence of an ignition source in the chamber and, above all, a risk of explosion.
- Seizure (as in epilepsy ) of the brain. It is caused by exposure to a high "dose" of oxygen. This side effect is very rare (1 occurrence in 3388 treatments, corresponding to 0.03% based on the number of treatments), but like every seizure of the brain, in principle dangerous ( risk of injury from uncontrolled movements, obstruction of the airways ). As a rule, however, oxygen-toxic seizures have no consequences. The likelihood of seizures occurring under HBO conditions depends on the one hand on the patient's state of health and on the other hand on the oxygen dose or exposure time to high oxygen concentrations. A prediction based on empirical data or calculations is not possible, however, because regardless of the relationships there is a high intra- and inter-individual variability.
- Myopia from exposure to oxygen. It is also caused by exposure to high "doses" of oxygen. The nearsightedness is only slightly pronounced and disappears completely. Using a head tent is more likely to occur, but this side effect affects as many as 50% of patients treated with more than 15 therapy units of HBO (but only noticed by very few).
- Damage to the lungs from oxygen ( ALI and ARDS ) is possible. It arises from exposure to a high " dose " of oxygen. The same clinical picture is also known in patients with long-term mechanical ventilation with 100% oxygen. Permanent lung damage is not to be expected with the appropriate use of the oxygen pressure therapy.
- Nausea , vomiting - rarely, due to volume change due to pressure, but also possible due to oxygen.
Cost and reimbursement
Statutory health insurance
The outpatient treatment by means of hyperbaric oxygen therapy is not a subject of the benefit package of health insurance in ambulatory patient care. As a rule, the costs of the treatment are to be borne by the patient himself (applications for reimbursement of costs are nevertheless made and a positive decision is made on an individual basis). Billing is based on the fee schedule for doctors as for the treatment of private patients . The Federal Social Court in its Decision of 7 May 2013 (Az. B 1 KR 44/12 R) decided that the statutory health insurance , the cost of outpatient HBO therapy for the indication diabetic foot has to take the stage Wagner III. It came into force on January 11, 2018 after the examination was completed.
Hyperbaric oxygen therapies for the indications marked with ¹ in the list of indications listed above are covered by the health insurances within the framework of inpatient treatment as part of the flat rate per case ( G-DRG ) based on a positive decision of the Federal Joint Committee . Hospitals would have to “buy in” hyperbaric oxygen therapy as an external service, unless they have their own pressure chambers.
Private health insurance
Private health insurances take over outpatient and inpatient treatments using hyperbaric oxygen therapy on request. The request should ideally contain a cost estimate for the planned treatment. Almost all German private health insurances, as well as the aid from civil servants, also cover the costs for the indications of acute acute hearing loss and acute tinnitus upon request. A claim to benefits is based on the applicable case law (OLG judgments in Koblenz and Stuttgart).
- Oxygen toxicosis
- Society for diving and hyperbaric medicine
- Association of German Pressure Chamber Centers
Sources and literature
Original papers and studies
- LK Weaver et al .: Hyperbaric oxygen for acute carbon monoxide poisoning. In: N Engl J Med . 347 (14), 3 Oct 2002, pp. 1057-1067. PMID 12362006 .
- NB Hampson et al. Carbon monoxide poisoning: interpretation of randomized clinical trials and unresolved treatment issues. In: Undersea Hyperb Med. 28 (3), 2001, pp. 157-164. PMID 12067152
- DN Juurlink et al: Hyperbaric oxygen for carbon monoxide poisoning. In: Cochrane Database Syst Rev. (1), 2005, p. CD002041. PMID 15674890 digitized version (PDF 2 MB)
- PA Voute et al .: Clinical experience with radiation enhancement by hyperbaric oxygen in children with recurrent neuroblastoma stage IV. In: Eur J Cancer . 31A (4), 1995, pp. 596-600. PMID 7576976
- AJ Van der Kleij, PA Voute: Treatment of recurrent stage IV neuroblastomas with 131I-MIBG and HBO Six years follow-up. In: Strahlenther Onkol . 172 Suppl 2, 1996, pp. 28-29. PMID 8946044
- J. Stankova include: 131I-meta iodobenzylguanidine in combination with hyperbaric oxygen therapy in the treatment of prognostically high-risk forms of neuroblastoma. In: Cas Lek Cesk. 140 (1), 2001, pp. 13-17. PMID 11242978
- MH Bennett et al .: Hyperbaric oxygenation for tumor sensitization to radiotherapy. In: Cochrane Database Syst Rev. (4), 2005, p. CD005007.
- MH Bennett et al .: Hyperbaric oxygen for idiopathic sudden sensorineural hearing loss and tinnitus. In: Cochrane Database Syst Rev. (1), 2005, p. CD004739. PMID 15674964
- M. Pilgramm, H. Lamm, K. Schumann: [Hyperbaric oxygen therapy in sudden deafness]. In: Laryngol Rhinol Otol. (Stuttg) 64 (7), 1985, pp. 351-354. PMID 3875776
- R. Dauman, D. Poisot, AM Cros et al .: [Sudden deafness: a randomized comparative study of 2 administration modalities of hyperbaric oxygenotherapy combined with naftidrofuryl]. In: Rev Laryngol Otol Rhinol. (Bord) 114 (1), 1993, pp. 53-58. PMID 8191053
- O. Zennaro, R. Dauman, A. Poisot et al .: [Value of the association of normovolemic dilution and hyperbaric oxygenation in the treatment of sudden deafness. A retrospective study]. In: Ann Otolaryngol Chir Cervicofac. 110 (3), 1993, pp. 162-169. PMID 8239337
- T. Nakashima, S. Fukuta, N. Yanagita: Hyperbaric oxygen therapy for sudden deafness. In: Adv Otorhinolaryngol. 54, 1998, pp. 100-109. PMID 9547880
- K. Lamm, H. Lamm, W. Arnold: Effect of hyperbaric oxygen therapy in comparison to conventional or placebo therapy or no treatment in idiopathic sudden hearing loss, acoustic trauma, noise-induced hearing loss and tinnitus. A literature survey. In: Adv Otorhinolaryngol. 54, 1998, pp. 86-99. PMID 9547879
- MA Dall'era et al .: Hyperbaric oxygen therapy for radiation induced proctopathy in men treated for prostate cancer. In: J Urol . 176, 2006, pp. 87-90. PMID 16753375
- D. Fink et al .: Hyperbaric oxygen therapy for delayed radiation injuries in gynecological cancers. In: Int J Gynecol Cancer. 16, 2006, pp. 638-642. PMID 16681739 .
- N. Bitterman: CNS oxygen toxicity. In: Undersea Hyperb Med. 31 (1), 2004, pp. 63-72. PMID 15233161 (full text)
- N. Hampson, D. Atik: Central nervous system oxygen toxicity during routine hyperbaric oxygen therapy. In: Undersea Hyperb Med. 30 (2), 2003, pp. 147-153. PMID 12964858 (full text, PDF, 690 kB)
- RM Leach et al: ABC of oxygen: Hyperbaric oxygen therapy. In: BMJ. 317 (7166), 1998, pp. 1140-1143. PMID 9784458 .
- PM Tibbles, JS Edelsberg: Hyperbaric-oxygen therapy. In: N Engl J Med. 334 (25), 1996, pp. 1642-1648. PMID 8628361 .
- S. Wiese et al .: Hyperbaric oxygenation: Characteristics of intensive care and emergency therapy. In: Anaesthesiologist. 2006. PMID 16625359 .
- Johannes von Reumont, Anke Fabian: The treatment of the bone marrow edema syndrome (KMÖS) - osteonecrosis. Indications, treatment strategies and clinical long-term results 1999 to 2011. Update 2011 and first 5-year follow-up in the treatment of BMES on the knee joint. Update of the presentations at the international diving and hyperbaric medicine congress in April 2008 in Heidelberg (PDF; 534 kB) . Pressure Chamber Center Heidelberg, November 15, 2014.
- Final report of the Federal Joint Committee according to Section 91 (7) SGB V on the indication field gas embolism (PDF; 813 kB)
- Final report of the Federal Joint Committee according to Section 91 (7) SGB V on the indication of clostridial myonecrosis (gas fire) (PDF; 448 kB)
- Final report of the Federal Joint Committee according to Section 91 (7) SGB V on the indication field decompression sickness (PDF; 1.0 MB)
- Final report of the Federal Joint Committee according to Section 91 (7) SGB V on the indication field carbon monoxide poisoning (PDF; 1.4 MB)
- Final report of the Federal Joint Committee according to Section 91 (7) SGB V on the indication field Perthes' disease (PDF; 300 kB)
- Final report of the Federal Joint Committee in accordance with Section 91 (7) SGB V on the indication of myocardial infarction (PDF; 508 kB)
- Final report of the Federal Joint Committee according to Section 91 (7) SGB V on the neuroblastoma indication field (PDF; 352 kB)
- Final report of the Federal Joint Committee in accordance with Section 91 (7) SGB V on the indication field head trauma (PDF; 509 kB)
- Final report of the Federal Joint Committee according to Section 91 (7) SGB V on the indication field of wide-angle glaucoma (PDF; 665 kB)
- Final report of the Federal Joint Committee according to Section 91 (7) SGB V on the HBO as a whole (PDF; 4.1 MB)
- g-ba.de (PDF 91 kB)
- Hyperbaric Oxygen Therapy (HBO) . Summary Report of the Working Committee "Medical treatment" of the Federal Committee of Physicians and Health Insurers on the deliberations of the years 1999 and 2000 to evaluate the hyperbaric oxygen therapy according to § 135 para. 1 SGB V . Published by the management of the "Medical Treatment" working committee of the Federal Committee of Doctors and Health Insurance Funds, April 11, 2000 (PDF).
- The Database of Randomized Controlled Trials In Hyperbaric Medicine ( Memento of April 28, 2009 in the Internet Archive )
- According to S3 guideline, AWMF-Register 091-001, developed by the German Society for Wound Healing and Wound Treatment , 2012.
- The Federal Committee of Doctors and Health Insurance Funds is one of the forerunners of the Federal Joint Committee (G-BA).