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THE ROLE OF HYPERBARIC OXYGEN THERAPY IN THE TREATMENT OF DIABETIC FOOT ULCERS ■ 123closed-space contained gas, as a gas-bubblein our body, will reduce to half its originaldiameter in submitted to the double or theambient pressure.3. Angiogenic effects - High levels of circulatingoxygen have been demonstrated to increasethe production of growth factorsres ponsible for promoting neovascularization(7, 8). This effect is responsible for theretinopathy of prematurity that occurs inpremature neonates’ retina, in which theexcessive vascular proliferation is proportionalto the FiO 2used.4. Neocolagenization Potentiation-Fibro blasticactivation only occurs when a PaO 2diffe -rential above 30-40mmHg 9 is found. Pathologicprocesses that produce gradual andchronic tissue hypoxia respond to HBOTwith incremental tecidual regenerationwhen oxygen is administered in an intermi -ttent dose.5. Hypoxic tissue preservation-HBOT providesenough oxygen for tissues with an acutecompromise of blood flow (10). Theincrease of plasma-dissolved oxygen by 15-fold directly accounts for a 4-fold increasedoxygen diffusion distance, from the peripheralcapillaries (6). This additional tecidualoxygenation is only maintained during deHBOT session but may allow a sufficientperfusion time to solve definitively theproblem and thus tissue preservation.6. Phagocytic capacity activation of polymorphonuclearleucocytes (PMNL) – PMNLdependent phagocytosis and bacteriallysis rely upon oxygen availability. In vitroand in vivo studies have demonstratedincreased neutrophilic and macrophagicactivity under high pressure and/or oxygenconditions (11, 12).7. Bacteriostatic and bactericidal effect - Somesporulated anaerobic bacteria do notresist in hyperoxic environments. Also, asynergic action takes place between certainantibiotics and oxygen, such asaminoglycosides or tobramycin, expandingtheir effective life-half (13).8. Toxin inactivation - Alfa-toxin of Clostridiumperfringens, responsible for the developmentof septic shock and a rapid evolutionof clostridial myonecrosis (gaseousgangrene) is inactivated by HBOT (14).9. Vasoconstriction-HBOT induces a selectivevasoconstriction in hyperoxic vascularterritories as vasodilatation takes place inhypoxic areas. This is known as Robin-Hood effect. This beneficial phenomenonmay be applied in compartimental syndrometreatment, acute ischaemic limbpathologies or in skin grafts to reduceinterstitial oedema15. Published studieshave demonstrated a reduction of fluidneeds in patients with severe burns, ifsubmitted to a HBOT protocol15.10. Carboxihaemoglobin elimination-Haemoglobin(Hb) has a 240-fold greater affinity forcarbon monoxide (CO) than oxygen. MeanCO-Hb ligation time breathing non-enrichedair at sea level is 520 minutes. However,a single HBOT session under 3 ATAreduces this time to 23 minutes (10, 16).INDICATIONSUndersea and Hyperbaric Medical Society(UHMS) leads a criterious approval processon all HBOT indications. The list of indicationsfor HBOT published by the UHMS (17) isused by insurance companies in the UnitedStates for comparticipation and refundablepurposes. It is important to state that insur-Figure 3. A patient currently on HBOT in ourInstitution-initial presentation.