Influence of hyperbaric oxygen therapy on thrombus formation ability in humans.

Background: Hyperbaric oxygen (HBO2) therapy was introduced nearly 300 years ago. However, its effect on thrombus formation is unclear. This may be because platelet and coagulation functions are unstable, yielding variable results; hence, accurate measurement is difficult. Our study aimed to analyze changes in thrombus formation before and after HBO2 therapy by using a total thrombus formation analysis system (TTAS). Methods: Six patients were prescribed HBO2 therapy for skin and soft tissue ulcers, and necrotic fasciitis. Blood samples were collected immediately before and after treatment. Then samples were put into a reservoir that connected to AR-chip to assess changes in the thrombus formation ability of both platelets and coagulation factors. We examined the differences in the thrombus formation ability using T-TAS. Time until the onset of white thrombus formation (T10) and complete occlusion of the capillary (T80) were analyzed by a two-way repeated measure analysis of variance (ANOVA). Results: The duration to pressure increase of samples after HBO2 therapy was longer than the duration before HBO2 therapy (p<0.05). This suggests decreased clot adhesiveness to the inner surface of the simulated blood vessel and reduced clot formation ability. Conclusions: The results for T10 and T80 suggest that HBO2 therapy reduced thrombus formation ability in the enrolled patients. We believe that T-TAS is a promising method to predict the efficacy of HBO2 therapy.

Effects of hyperbaric exposure on thrombus formation.

BACKGROUND: Hyperbaric oxygen (HBO2) therapy has a long history of use. However, its effect on thrombus formation is unclear. Many reports have indicated that it accelerates platelet aggregation, which suggests that it may increase thrombotic events. However, clinical trial results are inconsistent, and no previous reports have demonstrated that HBO2therapy does in fact increase thrombotic events. Here, we used a total thrombus formation analysis system (T-TAS) to analyze changes in thrombus formation in a specimen group exposed to constant hyperbaric pressure in vitro, and a control group. METHODS: Blood samples were collected from two sets of 10 healthy volunteers (mean age, 28.8 years) with no underlying disease. In the pressurized group, a constant pressure was applied to specimens in temperature-controlled test tubes; the non-pressurized group served as the control. Thrombus formation in samples from both the pressurized and control groups were measured using the T-TAS immediately, 20 minutes, and 40 minutes after pressurization. RESULTS: In the pressurized group, the onset of thrombus formation was significantly delayed, confirming a reduction in thrombus formation ability. However, the reduced ability for thrombus formation in the pressurized group recovered to the level of the control group. That is, the change in thrombus formation ability caused by pressure was proven to be reversible. CONCLUSIONS: We are the first to ascertain a decrease in the thrombus formation ability in specimens exposed to hyperbaric pressure using a T-TAS, which is capable of measuring thrombus formation in an environment similar to that in vivo.