A case-control questionnaire survey of decompression sickness risk in Okinawa divers.

BACKGROUND: Decompression sickness (DCS) is a rare condition that is often difficult to diagnose in deep-sea divers. Because of this, prevention and early diagnosis are important. In this case-control study, we examined the risk and preventive factors associated with DCS. METHODS: Our original questionnaire survey was conducted among 269 recreational divers in Okinawa. Divers who were diagnosed with DCS by a physician (n = 94) were compared with healthy recreational divers (n = 175). The questionnaire consisted of 30 items and included a dive profile. Odds ratios and multiple logistic regression analysis were used to estimate the relative risk of DCS. RESULTS: Logistic regression analysis revealed the following risk factors for DCS: a past history of DCS, drinking alcohol the evening before diving, indicating decompression stops, cold exposure after the dive, and maximum depth. Preventive factors included hydration before the dive, deep stops, safety stops and using nitrox gas. The results were reliable according to the Hosmer-Lemeshow and omnibus tests. CONCLUSION: We identified certain risk factors, together with their relative risks, for DCS. These risk factors may facilitate prevention of DCS among Okinawa divers.

A case-control study evaluating relative risk factors for decompression sickness: a research report.

BACKGROUND: Factors contributing to the pathogenesis of decompression sickness (DCS) in divers have been described in many studies. However, relative importance of these factors has not been reported. METHODS: In this case-control study, we compared the diving profiles of divers experiencing DCS with those of a control group. The DCS group comprised 35 recreational scuba divers who were diagnosed by physicians as having DCS. The control group consisted of 324 apparently healthy recreational divers. All divers conducted their dives from 2009 to 2011. The questionnaire consisted of 33 items about an individual's diving profile, physical condition and activities before, during and just after the dive. To simplify dive parameters, the dive site was limited to Izu Osezaki. Odds ratios and multiple logistic regression were used for the analysis. RESULTS: Odds ratios revealed several items as dive and health factors associated with DCS. The major items were as follows: shortness of breath after heavy exercise during the dive (OR = 12.12), dehydration (OR = 10.63), and maximum dive depth > 30 msw (OR = 7.18). Results of logistic regression were similar to those by odds ratio analysis. CONCLUSION: We assessed the relative weights of the surveyed dive and health factors associated with DCS. Because results of several factors conflict with previous studies, future studies are needed.

The effects of hyperbaric oxygen on tooth movement into the regenerated area after distraction osteogenesis.

OBJECTIVE: To analyze the effect of hyperbaric oxygen on newly formed bone in distracted areas surrounding the root of a moving tooth by histological and radiological analysis. It was hypothesized that the application of hyperbaric oxygen to a tooth moving into the distracted area would accelerate ossification and vascularization of newly formed bone in the distracted space. DESIGN: Ten dogs were used. After creating a 10-mm-long bone defect, a bony segment was prepared and translocated into the defect area at a rate of 1 mm/d for 10 days. Following the distraction period, tooth movement was started and the dogs were divided into two groups. The HBO group received hyperbaric oxygen; whereas, the control group did not. At 150 days after tooth movement, the distracted area around the moving tooth was evaluated radiologically and histologically. Differences between groups were confirmed by a Mann-Whitney U test. RESULTS: Trabecular bone density and cortical and subcortical bone areas measured by peripheral quantitative computed tomography in the HBO group were significantly higher than those in the control group. Histological observations revealed regenerated bone and blood vessels formation in the tension site of the moving tooth in the HBO group. The regenerated bone structure measured by bone histomorphometry was larger and more active in bone formation in the HBO group than in the control group. CONCLUSIONS: Applying hyperbaric oxygen to tooth movement into a distracted area appears to accelerate ossification and vascularization of regenerated bone in the that area.

Hyperbaric oxygen induces basic fibroblast growth factor and hepatocyte growth factor expression, and enhances blood perfusion and muscle regeneration in mouse ischemic hind limbs.

BACKGROUND: It is not clear how hyperbaric oxygen therapy (HBO) affects ischemia-induced pathophysiological responses such as angiogenesis and skeletal muscle regeneration. In the present study the effects of HBO on the functional and morphological recovery of ischemic hind limbs, blood perfusion and the local production of angiogenic growth factors were studied in a mouse model. METHODS AND RESULTS: Mice were placed in pure oxygen under 3 atm for 1 h/day for 14 days after the removal of a segment of the left femoral artery. HBO-treated mice showed better functional recovery and greater blood flow in the ischemic hind limb than untreated mice. Histological examination revealed unatrophied muscle fibers with islands of small regenerating muscle cells only in HBO-treated mice. Regeneration of muscle was confirmed by the increase in myf5 mRNA. The amount of mRNA for vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF) and basic fibroblast growth factor (bFGF) was slightly increased in the ischemic hind limbs. HBO eliminated the increase in VEGF mRNA. In contrast, the amount of mRNA for bFGF and HGF was further increased by HBO treatment. HBO transiently increased early growth response protein 1 (Egr-1) in the ischemic hind limbs. CONCLUSIONS: HBO accelerates the recovery of ischemic hind limbs by increasing the production of bFGF and HGF and by promoting muscle regeneration in mice.