In 1977, the first of a bi-yearly circular was developed and sent to the then known active hyperbaric chambers throughout the country. Over the ensuing 9 years a hyperbaric registry has been developed in which the locations, staffing patterns, diseases treated, affiliations of the chambers and trends of hyperbaric medicine have been followed up since the 1970s. Blue Cross/Blue Shield/Medicare/Medicaid, the major third party insurers, have agreed to payments in 14 conditions labeled the “accepted group” , which include gas embolism, radiation necrosis, decompression sickness, carbon monoxide poisoning, gas gangrene, refractory osteomyelitis, necrotizing fasciitis, soft tissue infections, crush injury, ischemic conditions, compromised skin grafts/skin flaps, wound healing enhancement, burns and anemia.
Negotiations may be undertaken in the treatment of 16 conditions in an investigative category. The accepted conditions are those where the body of literature, animal and clinical research, indicate that the use of hyperbaric oxygen is either the primary treatment （decompression sickness, air embolism, carbon monoxide poisoning） or adjunctive treatment. The Diver's Alert Network is a system whereby injured scuba divers or commercial deep sea divers may find the nearest and most appropriate hyperbaric chamber for recompression therapy on a 24-hour/7-days-per-week basis. There is a central telephone network at Duke University, Durham, NC, （919） 684-8111, and a second system through the Hyperbaric Registry located at the MIEMSS, （301） 328-7814.
The statistics of the registry will be presented. Of the 220 existing hyperbaric facilities, there are 85 multiplace, 118 monoplace, and 17 of both types. Over the 16 years （1971-1985） 44,095 patients have been treated for hyperbaric-related conditions. In this group 71.9% are in the accepted category and 28.1% are in the investigative and other categories.
As a result of the registry, one has been able to determine the trend in hyperbaric medicine and also the steady increase in its usage nationwide. From the original 37 chambers in 1977 to the 220 chambers in 1985, one has seen a dramatic increase in usage of hyperbaric oxygen.

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Human neutrophils phagocytosing or stimulated by soluble stimuli such as a synthetic chemotactic peptide and the calcium ionophore A23187, reduce molecular oxygen to reactive metabolites, such as superoxide anion, hydrogen peroxide and hydroxyl radicals. This respiratory burst, essential to the cell's bactericidal activity and significant in the pathogenesis of some inflammatory diseases, is catalyzed by NADPH Oxidase and results from oxidation of NADPH generated via the hexosemonophosphate shunt. The oxidase is considered to be composed of a flavoprotein and a b -type cytochrome and its activity is defective in chronic granulomatous disease. The biochemical mechanisms underlying the activation of the NADPH oxidane which is dormant in the resting cells are not well understood, but recest evidence has implicated a model as follows: Occupancy of receptors leads to activation of a GTP-binding protein（G protein）and the activated G protein then stimulates phospholipase C to cleave phosphatidylinositol 4, 5 -bisphosphate into two intracellular messengers 1, 2-diacylglycerol and inositol 1, 4, 5-trisphosphate, which activate protein kinase C and release calcium from intracellular storage sites, respectively. Increases in cytosolic calcium levels may activate calcium calmodulindependent protein kinase. The activation of NADPH oxidase could thus result from protein phosphorylation mediated by the protein kinases. The regulatory model proposed herein may be relevant to the stimulus-response coupling of other cells.

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Severe infected granulation wounds （ulcers） of upper and lower extremities result from various kinds of diseases, for example, peripheral arterial occlusive disease, postphlebitic venous insufficiency, arteriovenous malformation, skin cancer, trauma, etc. The wound managements of these ulcers are very difficult and almost all patients have a long period of the suffering, in general.
In order to accelerate the healing process of the ulcer, we have applied hyperbaric oxygen （OHP） together with conventional various therapies, because it is considered that oxygen plays one of important roles on wound healing. The OHP was performed on the condition of 2ATA. for 90 min. once a day, and the therapy was continuously given 25 times or more.
The results were as follows in our series consisted of 95 cases of ischemic ulcer, 10 cases of stasis ulcer, 5 cases of A-V malformation and one case of cancerous ulcer.
1. 62 out of 95 cases （65.3%） of ischemic ulcer, which resulted from unsuccessful vascular reconstruction, reocclusion of reconstructed blood vessels and/or advanced peripheral arterial occlusion, were cured by using the OHP with vasodilator drugs. All of these cases already received lumbal sympathectomy and didn't have any indication of surgical reoperation.
2. 10 cases of stasis ulcer received OHP before and after Linton's surgical procedure, and all cases have been set free from the ulcer in follow up studies for about 10 years.
3. 5 ceses of A-V malformaton received various surgical approaches, however, their ulcers didn't heal completely. OHP before and after skin graft on these ulcers was performed and all cases had successful results.
4. OHP with cancer chemotherapy was given on the cancerous ulcer case after burn, and the ulcer resection and skin graft were performed as cancer cells on the ulcer were not found microscopically in a few times of biopsy examination. The patient's ulcer was cured and no local recurrence was observed until he died by lung metastasis after 3 years and seven months of surgery.

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We studied autonomic nervous function during hypobaric pressure in ten volunteers by using a controlled-climate-room. The pressure was set at 360 mmHg, and the subjects were resided for three hours. The autonomic function was assessed by deep breathing testing （DB-test）. Second degree AV-block was observed in one subject and SVPCs were observed in two subjects only during the DB-test under hypobaric pressure. Mean heart rates increased during hypobaric pressure. The systolic blood pressure decreased significantly. However the heart rate variability as assessed by maximum heart rate minus minimum heart rate during DB-test did not change statistically. These findings suggest that hypobaric pressure of 360 mmHg provokes an increase in mean heart rate not due to withdrawal of parasympathetic tone. And the vagal reflex was suspected to be augmented, under hypobaric pressure.

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128 patients suffering from idiopathic sudden hearing loss were treated. 65 patients （group 1） were treated with stellate ganglion block （SGB） and hyperbaric oxygen therapy （HBO）, and 63 patients （group 2） were treated with SGB and HBO along with prostaglandin E₁（PGE₁）. The patients were given 0.25% bupivacaine for SGB and PGE₁ infusion for 30 min, and then exposed to oxygen at a 2.0 ATA for 60 min. 88% of group 1 and 94% of group 2 patients treated within 2 weeks after onset exhibited over 10 dB pure tone average improvement. 42% of the patients in group 1 and 73% of the patients in group 2 who were treated 2-4 weeks after onset had over 10 dB. All patients under 40 age bracket exhibited over 10 dB improvement except one case. From these data cited here, PGE₁ infusion combined with HBO and SGB would seem appropriate to furtherr expand application for idiopathic sudden hearing loss after 2 weeks onset.

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Authors studied the incidence of central nervous system oxygen toxicity in 218 brain injury patients through clinical convulsion or EEG paroxysm.
In 191 HBO （hyperbaric oxygenation） cases, two cases （1%） developed convulsion under 2 ATA which subsided by ceasing oxygen administration.
In 159 EEG test cases, four cases （3%） revealed EEG paroxysm under hyperoxemia which also subsided by stopping oxygen inhalation.
In 218 cases, six cases （2.7%） presented signs of CNS toxicity evaluated by convulsion or EEG paroxysm. In 218 cases, seven cases had history of convulsion and three of them （43%） developed convulsion or EEG paroxysm under hyperoxemic environment.
Cerebrovascular reactivity to hyperoxemia （“O₂ response”） to maintain homeostasis of brain will be disturbed in some cases with brain injury and these patients are vulnerable to present signs of oxygen toxicity. Attention must be paid when HBO therapy is scheduled for brain injury patients, especially for those having history of convulsion.

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A new methood for study of cardio-respiratory behavior under high pressure environment has been developed.
The measuring system is composed of gas sampiing systems （two types of breathing and atmospheric gas probes applied to pressures below and over 4ATA respectively）, a gas mixer, a pneumotachograph, a, Mass spectrometer and a data processor. The following measurement can be made by employing the system developed.
（1）Respiratory patterns of expired gases（Tv, FO₂, FCO₂, FN₂, FHe, FAr and FH₂O）for each breath cycle and their relevant factors（VE, VO₂, VCO₂, and R）measured by signal processing which improves the noise to signal ratio.
（2）Cardiac output measured by application of C₂H₂ mixture rebreathing method.
（3）Multibreath N₂ washout measured for component analysis of ventilation.
High response respiratory patterns of expired gases were taken across the wall of high pressure chamber used by specially designed gas sampling systems that can be made simultaneous and continuous measurement of respiratory gas concentrations and other ordinary physiological parameters.
Rapid response mesurement of the water vapour requires multidimensional analysis of ventilatory dynamics at high presure environment by programed online data processor.
This measurement provides clearer and wider informations for study of adaptive changes in man under high pressure environment.

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The purpose of this study is to evaluate the characteristics of oxygen toxicity. Rabbits were exposed to 50 or 100% oxygen and blood samples were obtained every twelve hours until 156 hours or death. Examined parameters were; Hydroxyl radical （•OH） production, GSH peroxidase （GPX）, lipoperoxidase （MDA） in plasma and superoxide dismutase （SOD） in RBC. •OH production varied considerably by oxygen exposures which was measured by electron spin resonance method. GPX increased more in the group which was exposed to 100% oxygen than those exposed to 50% oxygen. This result suggested that there could be possible increase of hydrogen peroxide. Plasma MDA increased only in those exposed to 100% oxygen, but SOD in RBC did not change significantly.
The real mechanism of •OH change was not clear, however, •OH could be one of the indexes to predict oxygen toxicity.

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A 55 year-old male was diagnosed as liver cirrhosis with esophageal varices. He developed hyperbilirubinemia after percutaneous transhepatic variceal obliteration（PTO）and splenic artery embolization（SAE）and was successfully treated with hyperbaric oxygenation therapy. As the patient was inoperable, so transcatheter embolization therapy had been prefered. A week after embolization, serum bilirubin level elevated gradually up to 10.7 mg/dl. Hyperbilirubinemia was refractory to predonisolone and other agents. Hyperbaric oxygenation therapy was performed thirty three times during fifty four days, and the level of serum bilirubin could be successfully reduced to 1.2 mg/dl and other clinical findings were also improved. This result suggested hyperbaric oxygenation therapy might be worthy to try for cirrhotic patients accompanied with hyperbilirubinemia and liver failure.

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