Evaluation of hyperbaric oxygen therapy for free flaps using planar optical oxygen sensors. Preliminary results

Progress in the study of mechanisms and pathways related to the survival of random skin flaps

The clinical application of random flaps in wound repair has been a topic of discussion. Random flaps are prone to necrosis due to the lack of well-defined vascular blood supply during transfer surgery. Their clinical utility is restricted, financial and psychological burdens is imposed on patients due to this limitation. The survival of random skin flaps depends on factors such as ischemia-reperfusion injury, oxidative stress, local inflammatory response, and neovascularization. This review aims to provide an overview of the evidence supporting the use of random flaps in clinical practice. In addition, this review explores the impact of different medications on signaling pathways within the flap's local microcirculation and investigates the interconnections between these pathways.

Hyperbaric Oxygen Therapy in Plastic, Aesthetic, and Reconstructive Surgery: Systematic Review

Introduction: Hyperbaric oxygen therapy (HBOT) has been used over the past six decades to treat multiple conditions. This systematic review aims to identify and evaluate the clinical outcomes of hyperbaric oxygen therapy in the field of plastic, reconstructive, and aesthetic surgery, found in the literature from the year 2000 to the present. Methods: A systematic review of the literature focused on the conceptual and methodological aspects of the PRISMA Declaration. The search for clinical trials focused on the results of hyperbaric therapy in plastic, reconstructive, and cosmetic surgery. The Newcastle–Ottawa scale suggested by the Cochrane manual was applied to each study. The study was carried out with a defined protocol and was registered in PROSPERO, with code CRD42022301261. Results: From the 170 articles identified, 6 were selected. Five of them showed that hyperbaric oxygen therapy favored the reduction of the size of skin ulcers and increased the formation of granulation tissue (two trials; p < 0.05), increased the partial pressure of transcutaneous oxygen in patients with free flaps (one trial; p < 0.001), reduced perfusion in keloid scarring disorder (one trial; p < 0.01), and accelerated both the fading of melanin pigmentation and the decrease in age spot size (one trial; p < 0.05). The methodological quality was moderate in all cases because there was no blinding method reported. One study failed to find differences in flap survival, time to resolution of venous congestion, resolution of edema, and postoperative recovery period (p > 0.05). Conclusions: Hyperbaric oxygen therapy has been increasingly used in the field of plastic and reconstructive surgery, and has shown potential benefits in promoting wound healing, reducing the risk of infection, and improving the survival of tissues used in reconstructive procedures. Further research with more rigorous clinical trials is needed to fully understand the efficacy and optimal use of this therapy in the field of plastic and reconstructive surgery.

Serum levels of nitric oxide and endothelin-1 in vasculopathy managed with hyperbaric oxygen therapy

Roles of nitric oxide (NO) and endothelin-1 (ET-1) in the local regulation of blood flow under physiological conditions are important and well known, while data on their effects and interactions in conditions of hyperbaric hyperoxia is still insufficient. This was a prospective observational study which included patients who underwent hyperbaric oxygen therapy (HBOT) in accordance with existing therapeutic protocol for peripherial arterial disease (PAD) during time period of six months, between january and july of 2016. Clinical stage of PAD according to Fontain was taken into account, as well as risk factors, demographic, anthropometric and clinical characteristics of studied patients. The study included 64 patients with a mean age (±Sd) 60.2±12.7 years, of whom 28 were female. Patients' NO serum levels in all observed categories before and after HBOT were not signifficantly different, except for stage II PAD (NObefore HBOT 21.9±9.6 vs. NOafter HBOT 26.2±12.1 (p = 0.04)). On the contrary, in all studied patients ET-1 level increased signifficantly after HBOT (ET-1before HBOT 4.2±11.6 vs. ET-1after 18.3±21.0 (p < 0.001)). Treatment of PAD using HBOT leads to the predominance of vasoconstrictor effects probably caused by elevation of serum ET-1 concentrations, while other factors such as exposure time to hyperbaric conditions, activation of antioxidant molecules, and the influx of other interfering substances must be considered in interpreting the effects of NO molecules.

Transcutaneous oxygen measurement using ratiometric fluorescence imaging as a valid method for monitoring free flap transplants

BACKGROUND

Reconstruction of soft tissue defects with free flaps is a common procedure in plastic and reconstructive surgery. Most postoperative complications occur within the first 48-72 hours after surgery. After postoperative complications, short perfusion restoration times may improve flap survival rates by up to 30-50%. Ratiometric fluorescence imaging is an additional or alternative method of postoperative flap monitoring.

OBJECTIVE

To test the efficacy and utility of transepidermal oxygen flux imaging to evaluate postoperative skin oxygenation of free and local flaps in the first 48 hours after surgery.

METHODS

The study included 32 patients (aged between 18 and 80 years; mean age 52.9) with a tissue defect covered with a free flap transplant at the Department of Plastic and Reconstructive Surgery of the University Medical Center Regensburg. Postoperative oxygen flux was measured with the 'VisiSens system' placed on the vascular pedicle as well as on the peripheral and central part of the flap.

RESULTS

Values of oxygen flux were higher in case of flap congestion (0.069±0.012) or flap necrosis (0.155±0.083) than in cases without any complications (0.061±0.006). Flux values of different areas of the same flap showed only minimal differences (central part: 0.065±0.008, peripheral part: 0.070±0.009, vascular pedicle: 0.056±0.004); the level of significance was p = 0.904.

CONCLUSION

Imaging transepidermal oxygen flux by ratiometric luminescence seems to be a reliable alternative, indirect method of postoperative flap monitoring with regard to microcirculatory function and flap viability.

Soft-tissue defects of the Achilles tendon region: Management and reconstructive ladder. Review of the literature

INTRODUCTION

Defects of the Achilles tendon region represent a challenge for reconstructive surgeons. Several options are available but there is still no reconstructive ladder for this specific and tricky area. An up-to-date reconstructive ladder according to local and general conditions is proposed based on our multicentre experience and an extensive review of the English literature on PubMed.

MATERIALS AND METHODS

An extensive review of the English literature was performed on PubMed using the following key-words: "Achilles region", "heel", "soft-tissue reconstruction", "flaps", "grafts" and "dermal substitutes".

RESULTS

A total of 69 complete papers were selected, covering the last thirty years' literature. Although most of the studies were based on limited case-series, local and general conditions were always reported. A comprehensive reconstructive ladder of all the available reconstructive techniques for the Achilles region has been created based on our personal multicentre experience and the results of the literature review.

CONCLUSIONS

The reconstructive ladder is a concept that is still a mainstay in plastic surgery and guides decisions in the repair strategy for soft tissue defects. The optimal solution, according to the experience of the surgeon and the wishes of the patient, is the one that implies less sacrifice of the donor site. Perforator flaps should be the first-line option for small-to-moderate defects; the distally-based sural flap is the most reported for moderate-to-large defects of the Achilles region, and free flaps should be reserved mainly for complex and wide reconstructions.

Real-Time Monitoring of Singlet Oxygen and Oxygen Partial Pressure During the Deep Photodynamic Therapy In Vitro

Photodynamic therapy (PDT) is an effective noninvasive method for the tumor treatment. The major challenge in current PDT research is how to quantitatively evaluate therapy effects. To our best knowledge, this is the first time to combine multi-parameter detection methods in PDT. More specifically, we have developed a set of system, including the high-sensitivity measurement of singlet oxygen, oxygen partial pressure and fluorescence image. In this paper, the detection ability of the system was validated by the different concentrations of carbon quantum dots. Moreover, the correlation between singlet oxygen and oxygen partial pressure with laser irradiation was observed. Then, the system could detect the signal up to 0.5 cm tissue depth with 660 nm irradiation and 1 cm tissue depth with 980 nm irradiation by using up-conversion nanoparticles during PDT in vitro. Furthermore, we obtained the relationship among concentration of singlet oxygen, oxygen partial pressure and tumor cell viability under certain conditions. The results indicate that the multi-parameter detection system is a promising asset to evaluate the deep tumor therapy during PDT. Moreover, the system might be potentially used for the further study in biology and molecular imaging.

Tissue oxygen tension monitoring of organ perfusion: rationale, methodologies, and literature review

Tissue oxygen tension is the partial pressure of oxygen within the interstitial space of an organ bed. As it represents the balance between local oxygen delivery and consumption at any given time, it offers a ready monitoring capability to assess the adequacy of tissue perfusion relative to local demands. This review covers the various methodologies used to measure tissue oxygen tension, describes the underlying physiological and pathophysiological principles, and summarizes human and laboratory data published to date.

Skin microcirculation in healthy term newborn infants--assessment of morphology, perfusion and oxygenation

Despite microcirculation's fundamental role, assessments of its function are limited. We explored the applicability of Computer Assisted Video Microscope (CAVM), Laser Doppler Perfusion Measurements (LDPM) and Diffuse Reflectance Spectroscopy (DRS) to study skin microvascular morphology, perfusion and oxygen saturation in twenty-five healthy newborns day 1-3 of life.

RESULTS

Day 1-3 (mean (SD)): Microvascular density (CAVM; number of microvessels crossing a grid of lines/mm line, c/mm): Chest: 11.3 (1.5), 11.0 (1.7), 10.7 (1.6). Hand: 13.2 (2.0), 13.2 (1.9), 12.4 (1.6). Capillary density was significantly higher in the hand than in the chest each day (p <  0.001). Perfusion (LDPM; arbitrary units): Chest: 109.1 (26.0), 101.4 (24.6), 100.8 (25.3). Hand: 58.9 (17.5), 54.3 (15.8), 46.9 (14.8). Perfusion was significantly higher in the chest than in the hand each day (p <  0.01). Microvascular oxygen saturation (DRS; %): Chest: 88.1 (5.2), 87.8 (10.0), 86.7 (9.0). Hand: 79.9 (15.2), 82.7 (11.8), 82.2 (12.1) (p <  0.05). Capillary flow velocities (CAVM) were similar in the chest and hand: 60-70% capillaries had "continuous high flow" and 30-40% "continuous low flow".Multimodal skin microvascular assessments with CAVM, LDPM and DRS are feasible with reproducible data in newborns. The hand has lower perfusion, higher capillary density and higher oxygen extraction than the chest.

Clinical and anatomical study of the distally based lesser saphenous veno-lateral sural neurocutaneous flap for lower extremity coverage

BACKGROUND

The distally based sural flap has been widely and successfully used to reconstruct soft tissue defects of the distal third of the lower leg and foot. Sensory loss and venous congestion are possible complications of this treatment, but there has been limited research focused on improving the sensory loss and veneous congestion. This study aimed to determine the spatial relationship between the lesser saphenous vein and the cutaneous nerves, the venous anatomy in the lower leg, and the nerve distribution in the lateral dorsum of the foot, and we presented our clinical experience.

MATERIALS AND METHODS

Twenty freshly amputated lower limbs were dissected in the 2 h following amputation. The lesser saphenous vein, medial/lateral sural nerve, and sural nerve were identified. Based on the anatomical studies, an island flap supplied by the vascular axis of the lesser saphenous vein and the lateral sural nerve was designed for clinical reparative applications in 24 cases.

RESULTS

We indicated the spatial relationship between the lesser saphenous vein and the cutaneous nerves and the venous anatomy in the lower leg. Among 24 flaps, 21 showed complete survival (87.5%), while marginal flap necrosis occurred in two patients (8.33%) and distal wound dehiscence in another (4.17%). No symptomatic neuromas were observed. Their appearance and functioning were satisfactory, with filling maintained in the heel and lateral side of the foot.

CONCLUSION

The distally based lesser saphenous veno-lateral sural neurocutaneous flap provides effective coverage of variable-sized soft tissue defects on the lower third of the lower leg and foot, without sensory loss and venous congestion.