Transcutaneous oximetry values in chronic ulcer patients during Hyperbaric treatment at 1.4 ATA compared to 2 ATA

Chronic wounds have a significant impact on a patient's quality of life. Different pathologies, such as poor blood supply and tissue breakdown, may lead to inadequate oxygenation of the wound. Hyperbaric oxygen (HBO2) is a widely used treatment for an increasing number of medical practices. A new so-called "hyperbaric treatment" trend has emerged. The use of low-pressure, soft-sided, or inflatable chambers represents a growing trend in hyperbaric medicine. Used in professional settings as well as directly marketed to individuals for home use, they are promoted as equivalent to clinical hyperbaric treatments provided in medical centers. However, these chambers are pressurized to 1.3 atmospheres absolute (ATA) on either air or with an oxygen concentrator, both generate oxygen partial pressures well below those used in approved hyperbaric centers for UHMS-approved indications. A total of 130 consecutive patients with chronic ulcers where tested. TcPO2 was measured near the ulcer area while the patient was breathing 100% O2 at 1.4 ATA for five and 10 minutes. The average TcPO2 at 1.4 ATA after 10 minutes of O2 breathing was 161 mmHg (1-601 mmHg, standard deviation 137.91), compared to 333 mmHg in 2 ATA (1-914±232.56), p < 0.001. Each electrode tested was also statistically significant, both after five minutes of O2 breathing and after 10 minutes. We have not found evidence supporting the claim that 1.4 ATA treatment can benefit a chronic ulcer patient. The field of HBO2 is constantly evolving. We have discovered new ways to treat previously incurable ailments. Nevertheless, it is important to note that new horizons must be examined scientifically, supported by evidence-based data. The actual effect of 1.4 ATA on many ailments is yet to be determined.

Long-term effects of hyperbaric oxygen therapy on visual acuity and retinopathy

Hyperbaric oxygen (HBO2) therapy is an adjunct treatment for diabetic foot ulcers. Since plausible mechanisms of action for this treatment include increased angiogenesis and high tissue oxygen concentrations, concerns about deterioration of retinopathy have been raised. The aim of this study was to evaluate the effects of HBO2 on visual acuity (VA) and retinopathy in patients with chronic diabetic foot ulcers during a two-year follow-up period. This is a randomized, single-center, double-blinded and placebo-controlled clinical trial evaluating the effects of HBO2 in patients with diabetes mellitus and chronic foot ulcers. All study participants underwent an ophthalmological examination before the first study treatment and then at three, six, 12 and 24 months. Fifty patients with a median age of 67 years were included. Visual acuity was similar between groups and did not change during the two-year observation period. No differences in retinopathy were seen between groups; neither were any differences found in numbers or areas of bleedings, hard exudates, microaneurysms or edemas, nor between groups or visits. New clinically significant macular edema was identified in four eyes in the HBO2 group and in three eyes in the placebo group. In this population of diabetic foot ulcer patients HBO2 seems to be neutral in an ophthalmological perspective. From a retinal point of view, we could not identify any indication of harmful effects of HBO2 on the microvascular bed in the placebo group.

Optimal switching time control of the hyperbaric oxygen therapy for a chronic wound

Chronic wounds, defined as those wounds which fail to heal through the normally orderly process of stages and remain in a chronic inflammatory state, are a significant socioeconomic problem. This paper considers an optimal switching time control problem of the hyperbaric oxygen therapy for a chronic wound. First, we model the spatiotemporal evolution of a chronic wound by introducing oxygen, neutrophils, invasive bacteria, and chemoattractant. Then, we apply the method of lines to reduce the partial differential equations (PDEs) into ordinary differential equations (ODEs), which lead to an ODE optimization problem with the changed time switching points. The time-scaling transformation approach is applied to further transform the control problem with changed switching time into another new problem with fixed switching time. The gradient formulas of the cost functional corresponding to the time intervals are derived based on the sensitivity analysis. Finally, computational numerical analysis demonstrates the effectiveness of the proposed control strategy to inhibit the growth of bacterial concentration.

Visualization of angiogenesis and vasculogenesis in a late tissue radiation injury of the chest wall treated with adjuvant hyperbaric oxygen therapy using fluorescence angiography

Adjuvant radiation therapy for breast cancer treatment often involves high doses of radiation, making patients more susceptible to late radiation tissue injury (LRTI), severe complications of which involve necrosis and ulceration. Treatment of such wounds is challenging. One modality that can be utilized is hyperbaric oxygen (HBO2) therapy. However, an optimal dose and the objective evidence of its benefit in use as an adjunctive treatment modality is limited. Presented here is a case of a non-surgical candidate in which serial indocyanine green fluorescence angiography (ICGFA) was utilized to determine if it could detect changes in tissue perfusion over the course of treatment. Serial ICGFA allowed for visualization of the current phase of wound healing, angiogenesis and vasculogenesis. Future large studies should be employed to better determine the utility of serial ICGFA to improve HBO2 utilization in patients who are undergoing HBO2 as part of their course of treatment for LRTI.

The use of indocyanine green fluorescence angiography to assess perfusion of chronic wounds undergoing hyperbaric oxygen therapy

OBJECTIVE

The purpose of this study is to determine the utility of using indocyanine green fluorescence angiography (IGFA) in assessing perfusion of chronic wounds after hyperbaric oxygen (HBO2) therapy.

METHODS

From May 2016 to January 2018, 26 patients underwent both HBO2 and IGFA. A near-infrared charge-coupled camera measured the flow of intravenous indocyanine green into the wound. IGFA was done pre-HBO2, after approximately 10 HBO2 sessions, and upon completion of HBO2. The ingress rate at baseline, mid-therapy and post-HBO2 values were compared using descriptive statistics.

RESULTS

A total of 26 chronic wounds were identified. Baseline median ingress rate was 0.90 units/second (IQR: 0.28 to 6.10). Median ingress rate after approximately of 10 HBO2 sessions was 2.45 units/sec (IQR: 0.48 to 6.35). Six of 11 patients, however, exhibited a decrease in ingress rate from baseline to mid-therapy. Finally, median ingress rate post-HBO2 was 3.70 units/second (IQR: 0.30 to 9.90). Median increase in ingress and rate from baseline to mid-HBO2 treatment 0.30 units/second (IQR: -0.25 to 3.10) and from mid- to post-HBO2 was -0.40 units/second (IQR: -1.50 to 2.60).

CONCLUSIONS

This preliminary study shows capability of IGFA to detect changes in blood flow to wounds following HBO2 therapy. Results support the use of IGFA to evaluate the changes in perfusion of patients undergoing HBO2 for chronic wounds. A larger sample size may help clarify the benefit of IGFA to predict potential for wound healing.