Hyperbaric oxygen therapy mitigates left ventricular remodeling, upregulates MMP-2 and VEGF, and inhibits the induction of MMP-9, TGF-β1, and TNF-α in streptozotocin-induced diabetic rat heart

AIMS

Hyperbaric oxygen (HBO) therapy has been widely used for the adjunctive treatment of diabetic wounds, and is currently known to influence left ventricular (LV) function. However, morphological and molecular repercussions of the HBO in the diabetic myocardium remain to be described. We aimed to investigate whether HBO therapy would mitigate adverse LV remodeling caused by streptozotocin (STZ)-induced diabetes.

MAIN METHODS

Sixty-day-old Male Wistar rats were divided into four groups: Control (n = 8), HBO (n = 7), STZ (n = 10), and STZ + HBO (n = 8). Diabetes was induced by a single STZ injection (60 mg/kg, i.p.). HBO treatment (100% oxygen at 2.5 atmospheres absolute, 60 min/day, 5 days/week) lasted for 5 weeks. LV morphology was evaluated using histomorphometry. Gene expression analyzes were performed for LV collagens I (Col1a1) and III (Col3a1), matrix metalloproteinases 2 (Mmp2) and 9 (Mmp9), and transforming growth factor-β1 (Tgfb1). The Immunoexpression of cardiac tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) were also quantified.

KEY FINDINGS

HBO therapy prevented LV concentric remodeling, heterogeneous myocyte hypertrophy, and fibrosis in diabetic rats associated with attenuation of leukocyte infiltration. HBO therapy also increased Mmp2 gene expression, and inhibited the induction of Tgfb1 and Mmp9 mRNAs caused by diabetes, and normalized TNF-α and VEGF protein expression.

SIGNIFICANCE

HBO therapy had protective effects for the LV structure in STZ-diabetic rats and ameliorated expression levels of genes involved in cardiac collagen turnover, as well as pro-inflammatory and pro-angiogenic signaling.

Evaluation of the Occlusive Arterial Disease and Diabetic Angiopathy Treatment Effects by Hyperbaric Oxygenation

Introduction:

One of the most severe complications of atherosclerosis is arterial occlusive disease (AOD) and with diabetic angiopathy (DA), is a common chronic problem in clinical practice worldwide. Hyperbaric oxygen (HBO) therapy is a therapeutic modality for solving all forms of hypoxia.

Aim:

To compare the treatment with HBO therapy in patients with AOD and DA ischemic symptomatology with standard treatment i.e. vasodilators, antibiotics, antiplatelets and statins, and to demonstrate the benefit of the therapeutic modality itself.

Methods:

We conducted a clinical prospective study and included a total of 80 patients, divided into two groups: 40 patients with the arterial occlusive disease and lower-extremity wounds, with sub-group (n=20) treated with HBO therapy on the top of the standard therapy and 40 patients with diabetic angiopathy and diabetic lower-extremity wounds, with sub-group (n=20) treated with HBO therapy on top of the standard therapy.

Results:

The efficacy of therapy in patients treated with HBO therapy on the top of standard therapy was significantly higher than in the group of HBO non-treated patients. There was a significant improvement in 9 patients treated with HBO therapy, while in HBO non-treated patients the significant improvement effect was observed only in one patient.

Conclusion:

HBO therapy is an effective therapeutic component in the healing of diabetic lower-extremity wounds in the patients with AOD and DA. In our patients HBO therapy on the top of standard therapeutic protocol has an effect of reducing the number of lower-limb amputations in patients with AOD and DA. These results support clinical use of HBO therapy for diabetic lower-extremity wound healing.

Hyperbaric oxygen therapy reduces the risk of QTc interval prolongation in patients with diabetes and hard-to-heal foot ulcers

AIMS

Heart rate corrected QT (QTc) interval prolongation is a risk factor associated with increased mortality. Hyperbaric oxygen therapy (HBO) has previously been shown to have acute beneficial effects on QTc dispersion. The aim of this study was to evaluate long-term effects of HBO on QTc time in diabetic patients with hard-to-heal foot ulcers.

METHODS

In a prospective, double-blinded placebo-controlled study, patients were randomized to 40 treatment sessions with either HBO or air (placebo), at 2.5 ATA. Patients fulfilling >35 completed treatment sessions were included in the evaluation.

RESULTS

Of the initial 75 patients (38 HBO/37 placebo), two were excluded due to pacemaker use. Baseline characteristics were similar between groups. At the 2-year follow-up, QTc time was significantly shorter in the HBO compared to the placebo group (438 vs. 453ms, p<0.05). Further, fewer HBO treated patients had a QTc time >450ms (22 vs. 53 %, p<0.02). This difference seemed to be caused by a significant prolongation of the QTc interval in the placebo group (427 (419-459) at baseline vs. 456ms (424-469) after 2years), whereas no significant change was seen in HBO treated patients.

CONCLUSIONS

HBO treatment might protect against QTc prolongation in this high-risk diabetic population.

Hyperbaric oxygen therapy as adjunctive treatment of diabetic foot ulcers

The widespread use of HBO as an adjunctive treatment of diabetic foot ulcers has been founded on weak scientific evidence, but the consistency in positive outcomes in trials evaluating HBO on ulcer healing is noteworthy, not least as these results are in concert with data from in vitro and physiologic studies supporting the theoretical framework of HBO reversing hypoxia-induced abnormality. The long-term ulcer-healing rates of the nonrandomized controlled studies before the recent study by Margolis and colleagues, 77% with HBO versus 25% with standard treatment, are in concert with 1-year follow-up data from the 2 double-blind RCTs, 54% versus 25%. These 2 trials have put the use of HBO on firmer ground, but several issues, including health economics, developing robust selection criteria for treatment, optimizing treatment protocols, and identifying standards for when to start and stop treatment, remain to be elucidated. Not least, outcomes from further high-quality studies are needed. At present, HBO may be used as an adjunctive therapy in a select group of patients with diabetic foot ulcers that are difficult to heal.

The role of hyperbaric oxygen in the treatment of diabetic foot ulcers

Diabetic foot ulcers are still extremely difficult to heal. Therefore, therapeutic options to improve healing rates are continuously being explored. Hyperbaric oxygen (HBO) has been used in addition to standard treatment of the diabetic foot for more than 20 years. Evidence suggests that HBO reduces amputation rates and increases the likelihood of healing in infected diabetic foot ulcers, in association with improved tissue oxygenation, resulting in better quality of life. Nonetheless, HBO represents an expensive modality, which is only available in few centers. Moreover, adverse events necessitate a closer investigation of its safety. Finally, it is not entirely clear which patients stand to benefit from HBO and how these should be selected. In conclusion, HBO appears promising, but more experience is needed before its broad implementation in the routine care of the diabetic foot.