Hyperbaric Oxygen Therapy (HBO) is based On pure oxygen (O2) breathing inside a hyperbaric chamber pressurized above the atmospheric level. HBO has been known for more than 300 years despite the fact that only in the last 30 has it been used properly. HBO has wide diffusion in the USA, the Russia and certain European countries.
Breathing 100% oxygen in the hyperbaric environment causes an increase in O2 arterial blood pressure over 2000 mmhg. Free O2 dissolved in plasma, not haemoglobin linked, is then increased more than 22 times, and thus can have a therapeutic effect on all diseases causing general or tissular hypoxia.
HBO produces generalized not hypoxaemic peripheral vasoconstriction; it stimulates microneovascularization, neocollagenation, and oxygen-dependent polymorpho-nuclear (PMN) bacterial phagocytic-killing; it has a bactericidal effect on sporulate anaerobic germs and a bacteriostatic effect on both non-sporulate anaerobic germs and some strains of aerobic ones; it blocks clostridium-perfringens toxin production; it decreases the volume of extravascular and intravascular dysbaric embolizing bubbles; it quickly eliminates Carboxyhaemoglobin (HbCO) in cases of carbon monoxide poisoning. The pressure increase can produce barotraumatic injuries in the ENT system, empty organic air caves and in lungs, ant can also cause reversible acute toxic effects in the CNS, and some chronic respiratory effects. Among current therapeutic procedures these side effects are actually exceptional.
Decompression Illnesses (DI) can produce severe neurological and haemodynamic disorders. HBO achieved a favourable results in 88.1% of the 222 cases treated. DI constitute a PREFERENT indication for HBO.
Carboxyhaemoglobin (HbCO) is produced in cases of Carbon Monoxide Poisoning (CMP). It displaces the haemoglobin saturation curve to the left, compromises blood oxygen transport, causes direct cellular damage, CNS demyelinization, and late neurological syndrome. HBO accelerates HbCO elimination from 530 to 23 minutes, ameliorates tissue hypoxia, and prevents neurological sequelae, for which it is the PREFERENT treatment OF CMP. Full recoveries were obtained in 65 of the 69 treated cases (98.5%).
Gas Gangrene (GG) is a necrotizing soft tissue infection produced by clostridium perfringenswhich causes wide tissue necrosis, gas tissue infiltration, putrid smell, haemolysis, and frequently, death. HBO enhances reduction-oxidation tissue potentials and blocks toxin production; it has a bactericidal effect on clostridium, increases the haemolytical reduced blood oxygen transport, enhances tissue oxygenation, makes evident the actual extension of the infection, and clearly indicates the tissues which are still valid. HBO is the PREFERENTtreatment for GG, and is simultaneously used with antibiotic therapy and surgical debridement. Favourable results were obtained in 70% of the 24 cases treated. Two patients (4.2%) died due to a GG related cause.
In other Soft Tissue Necrotizing Infections HBO has a COMPLEMENTARY effect increasing tissue O2 pressure, stimulating PMN phagocytic bacterial killing, and exerting a bacteriostatic effect on both non-sporulate anaerobic germs and some strains of aerobic ones. Favourable results were obtained in 70% of cases of Fournier's Gangrene, and Necrotizing Fascitis. Related mortality occurred in 2 cases (12,5%).
Some Chronical Refractory Osteomyelitis and Osteoradionecroses often have a very long term evolution. HBO produces a bacteriostatic action on the responsible germs, modifies osteoclastic activity, optimizes antibiotic bioavailability, and enhances local defence mechanisms; it constitute a good COMPLEMENTARY treatment. Favourable results were obtained in 8 of the 12 treated patients.
Wound Healing Disorders caused by hypoxic mechanisms are common in vasculopathies. OHB exerts a COMPLEMENTARY effect by increasing O2 tissue tension which stimulates neovascularization, neocollagenation and granulation. Good results were obtained in 33 of the 48 treated cases (64.6%).
Acute Arterial Retinal Occlusion produces sudden blindness due to the extreme sensitivity of the retina to hypoxia. The choroidal circulation can, in these cases, adopt a supporting function when optimized by HBO which constitutes the basis of its EXPERIMENTAL application. Twenty patients were treated, and half showed remarkable objective improvement in both visual function and visual fields post treatment.
In Postanoxic Brain Syndromes, HBO may be EXPERIMENTALLY used to accelerate neurological sequelae improvement and recovery of damaged functions. Four patients who were in neurovegetative state for some weeks, showed some functional increase and a marked improvement in quality of life following the HBO treatment.
Seven hundred and sixty two references are reviewed and listed in the same order as are mentioned in the text.
Barcelona, June 1987
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