The effectiveness of hyperbaric oxygen treatment in tracheal reconstruction with auricular cartilage grafts (experimental study)

Hyperbaric oxygen therapy in the prevention and management of tracheal and oesophageal anastomotic complications

OBJECTIVES

Failure of anastomotic healing is a morbid complication after airway or oesophageal surgery. Hyperbaric oxygen therapy (HBOT) has been used extensively in the management of complex wound-healing problems. We demonstrate the use of HBOT to rescue at-risk anastomoses or manage anastomotic failures in thoracic surgery.

METHODS

Retrospective review of 25 patients who received HBOT as part of the management of tracheal or oesophageal anastomotic problems during 2007-2018. HBOT was delivered at 2 atm with 100% oxygen in 90-min sessions.

RESULTS

Twenty-three patients underwent airway resection and reconstruction while 2 patients underwent oesophagectomy. There were 16 (70%) laryngotracheal and 7 (30%) tracheal resections. Necrosis at the airway anastomosis was found in 13 (57%) patients, partial dehiscence in 2 (9%) patients and both in 6 (26%) patients. HBOT was prophylactic in 2 (9%) patients. Patients received a median of 9.5 HBOT sessions (interquartile range 5-19 sessions) over a median course of 8 days. The airway anastomosis healed in 20 of 23 (87%) patients. Overall, a satisfactory long-term airway outcome was achieved in 19 (83%) patients; 4 patients failed and required reoperation (2 tracheostomies and 1 T-tube). HBOT was used in 2 patients after oesophagectomy to manage focal necrosis or ischaemia at the anastomosis, with success in 1 patient. Complications from HBOT were infrequent and mild (e.g. ear discomfort).

CONCLUSIONS

HBOT should be considered as an adjunct in the management of anastomotic problems after airway surgery. It may also play a role after oesophagectomy. Possible mechanisms of action are rapid granulation, early re-epithelialization and angiogenesis.

Therapeutic Effects of Hyperbaric Oxygen in the Process of Wound Healing

Chronic and non-healing wounds, especially diabetic foot ulcers and radiation injuries, imply remarkable morbidity with a significant effect on the quality of life and a high sanitary cost. The management of these wounds requires complex actions such as surgical debris, antibiotic treatment, dressings and even revascularization. These wounds are characterized by poor oxygen supply resulting in inadequate oxygenation of the affected tissue. The adjuvant treatment with hyperbaric oxygen therapy (HBOT) may increase tissue oxygenation favoring the healing of wounds which do not respond to the usual clinical care. The increase in the partial pressure of oxygen contributes to cover the energy demands necessary for the healing process and reduces the incidence of infections. Moreover, the increase in oxygen leads to the production of reactive species with hormetic activity, acting on signaling pathways that modulate the synthesis of inflammation mediators, antioxidants and growth factors which can contribute to the healing process. Studies performed with cell cultures and in animal models seem to demonstrate the beneficial effects of HBOT. However, clinical trials do not show such conclusive results; thus, additional randomized placebo-controlled studies are necessary to determine the real efficacy of HBOT and the mechanism of action for various types of wounds.

The protection effect and mechanism of hyperbaric oxygen therapy in rat brain with traumatic injury

PURPOSE

To investigate the effect of hyperbaric oxygen therapy (HBOT) on traumatic brain injury (TBI) outcome.

METHODS

The modified Marmarou's weight drop device was used to generate non-lethal moderate TBI rat model, and further developed in vitro astrocytes culturing system. Then, we analyzed the expression changes of interested genes and protein by quantitative PCR and western blot.

RESULTS

Multiple HBO treatments significantly reduced the expression of apoptosis promoting genes, such as c-fos, c-jun, Bax and weakened the activation of Caspase-3 in model rats. On the contrary, HBOT alleviated the decrease of anti-apoptosis gene Bcl-2 and promoted the expression of neurotrophic factors (NTFs), such as NGF, BDNF, GDNF and NT-3 in vivo. As a consequent, the neuropathogenesis was remarkably relied with HBOT. Astrocytes from TBI brain or those cultured with 21% O2 density expressed higher NTFs than that of corresponding controls, from sham brain and cultured with 7% O2, respectively. The NTFs expression was the highest in astrocytes form TBI brain and cultured with 21% O2, suggesting a synergistic effect existed between TBI and the following HBO treatment in astrocytes.

CONCLUSION

Our findings provided evidence for the clinical usage of HBO treating brain damages.

Safety of hyperbaric oxygen therapy for management of central airway stenosis after lung transplant

BACKGROUND

Central airway stenosis (CAS) is common after lung transplantation and causes significant post-transplant morbidity. It is often preceded by extensive airway necrosis, related to airway ischemia. Hyperbaric oxygen therapy (HBOT) is useful for ischemic grafts and may reduce the development of CAS.

METHODS

The purpose of this study was to determine whether HBOT could be safely administered to lung transplant patients with extensive necrotic airway plaques. Secondarily, we assessed any effects of HBOT on the incidence and severity of CAS. Patients with extensive necrotic airway plaques within 1-2 months after lung transplantation were treated with HBOT along with standard care. These patients were compared with a contemporaneous reference group with similar plaques who did not receive HBOT.

RESULTS

Ten patients received HBOT for 18.5 (interquartile range, IQR 11-20) sessions, starting at 40.5 (IQR 34-54) days after transplantation. HBOT was well tolerated. Incidence of CAS was similar between HBOT-treated patients and reference patients (70% vs 87%, respectively; P=.34), but fewer stents were required in HBOT patients (10% vs 56%, respectively; P=.03).

CONCLUSIONS

This pilot study is the first to demonstrate HBOT safety in patients who develop necrotic airway plaques after lung transplantation. HBOT may reduce the need for airway stent placement in patients with CAS.

Is Tracheal Transplantation Possible With Cryopreserved Tracheal Allograft and Hyperbaric Oxygen Therapy? An Experimental Study

BACKGROUND

Allografts have achieved prominence for tracheal reconstruction because of their natural physiologic and anatomic structure, which preserves respiratory tract flexibility and lumen patency. The immunomodulatory effects of cryopreservation prevent tracheal allograft rejection. In addition, hyperbaric oxygen therapy (HBOT) accelerates wound healing by promoting epithelization and neovascularization. This experimental study investigated the early and late effects of HBOT on cryopreserved tracheal allografts (CTAs).

METHODS

The study used 33 outbred Wistar rats weighing 300 to 350 g as allograft transplantation donors and recipients. Among these, 22 recipient rats were randomly assigned to the HBOT (n = 11) and control (n = 11) groups. Rats in the HBOT group were treated with 100% oxygen for 60 minutes at 2.5 atmospheres of absolute pressure for 7 days. Recipient rats in both groups were euthanized at 1 week (n = 5) and 4 weeks (n = 6) after transplantation, defined as the early and late periods, respectively.

RESULTS

In the early period, no significant histopathologic differences were observed between groups (p > 0.05). However, microscopic evaluation of the control group during the late period showed low epithelization of the CTA. In contrast, microscopic evaluation of the HBOT group during this same period revealed epithelium covering the transplanted CTA lumen. Significant epithelization and vascularization and significantly reduced inflammation and fibrosis were found in the HBOT group compared with the control group (p < 0.05).

CONCLUSIONS

HBOT may be effective in tracheal reconstruction by increasing epithelization and neovascularization after extended tracheal resection. HBOT, therefore, should be considered in CTA transplantation.

The effect of surgical denervation on prevention of excessive dermal scarring: a study on rabbit ear hypertrophic scar model

BACKGROUND

Previous reports have suggested that the extent of wound contraction, epithelisation and total healing time were influenced by denervation of tissues. In this article, we studied for the first time the effect of sensory denervation on prevention of excessive dermal scarring.

MATERIALS AND METHODS

Sixteen New Zealand white rabbits were used. Denervation of the right ears was performed by surgical excision of two main sensory nerves. Dissections were also performed on left ears without any nerve excision for the control group. After 14 days of follow-up and confirmation of tissue denervation, an excessive dermal scarring model as defined by Morris et al. was made by surgery on both ears. Twenty-eight days after making the wounds, the tissues were extirpated for analyses. The scars were evaluated by the scar elevation index (SEI), epithelisation time and inflammatory cell count.

RESULTS

The SEI of the denervated side scars was significantly lower than that of the non-denervated side. The rate and timing of total epithelisation and inflammatory cell count between groups yielded no difference.

CONCLUSIONS

In this study, the surgical denervation skin reduced scarring. It was suggested that understanding the exact role of sensory nerves and neural mediators in excessive dermal scarring is necessary for the prevention and treatment of scarring.

Esterified hyaluronic acid improves cartilage viability in experimental tracheal reconstruction with an auricular graft

OBJECTIVE: The aim of this study was to determine the efficacy of esterified hyaluronic acid (HYAFF) on the vitality of auricular cartilage grafts used for tracheoplasty, with respect to macroscopic and microscopic parameters.

STUDY DESIGN: Prospective, controlled.

SETTING: Academic research laboratory.

SUBJECTS AND METHODS: The study included 14 New Zealand rabbits acquired specifically for the study. The rabbits were divided into two groups: the control group, in which free cartilage grafts were not exposed to any materials or additional procedures (n = 7), and the hyaluronic acid (HA) treatment group, in which auricular grafts and anastomosis lines were covered with HYAFF (n = 7). Free auricular cartilage grafts used for the reconstruction of experimentally created tracheal defects were anastomosed extraluminally. All the rabbits were sacrificed two months post surgery. Samples were collected and examined histopathologically. The sections were stained with hematoxylineosin, Masson's trichrome, and inducible nitric oxide synthase (iNOS) and examined under a light microscope.

RESULTS: Fibrosis and cartilage mass significantly differed between the control and HYAFF group ( P < 0.05). Immunohistochemical examination showed that more chondrocytes stained with iNOS in the control group than in the HYAFF group, according to histologists' observations.

CONCLUSION: HYAFF catalyzed wound healing with less fibrous tissue formation, had chondroprotective and stimulatory effects on chondrocyte metabolism, and decreased nitric oxide production and apoptosis via improving the nourishment of free auricular cartilage grafts, subsequently preventing hypoxia and oxidative stress, particularly in the early postimplantation period.

Effect of hyperbaric oxygen on survival of composite grafts in rats

Most treatment with hyperbaric oxygen (HBO) in plastic surgery is for wounds, burns, crush injuries, and infections. We aimed to find out if HBO increases the survival of composite grafts in rats. Twenty Sprague-Dawley rats were randomly assigned to two equal groups (treatment and control). A template 30 x 30 mm was placed on the skin and a composite graft taken from the upper back was harvested and then resutured to the fascia in situ. The treated group was placed in a hyperbaric chamber set at 202 kPa and 100% oxygen for 90 minutes daily for two weeks. Control animals were given no treatment. After death the mean surviving internal surface area of the graft was 372.5 (117.9) mm2 in the control group and 561.3 (85.7) mm2 in the experimental group (p=0.001). Treatment with HBO improved the surviving area of composite grafts in rats, and the beneficial effect was prominent only on the inner surface of the graft.

Effectiveness of topically applied halofuginone in management of subglottic stenosis in rats

OBJECTIVE

The aim of the study is to ascertain the antifibrotic effect of topically applied halofuginone after acute subglottic injury.

MATERIALS AND METHODS

After standardized trauma to subglottic area, rats were divided into two groups: the study group that received treatment and the control group that did not. The subjects were treated with topical application of cottonoid soaked in 30 mg/dL halofuginone solution for 5 minutes after subglottic trauma. The larynx specimens were examined histopathologically by light microscopy to assess fibrosis, epithelialization, inflammation, and necrosis.

RESULTS

The fibrosis indexes of the treated group were significantly less than those of the control group (P < 0.05).

CONCLUSIONS

Topically applied halofuginone hydrobromide decreases fibrosis/scar tissue formation secondary to experimentally induced acute subglottic trauma.

Effects of halofuginone on fibrosis formation secondary to experimentally induced subglottic trauma

OBJECTIVE

The aim of the study was to assess the antifibrotic effect of systemically applied halofuginone after subglottic injury.

MATERIALS AND METHODS

After standardized trauma to subglottic area, rats were divided into two groups: a study group that received treatment and a control group that did not. The rats were treated with 0.1 mg/kg/day intraperitoneal halofuginone injection for 30 days. The larynx specimens were examined histopathologically under light microscope for epithelization, inflammation, necrosis, and fibrosis.

RESULTS

The fibrosis indexes of the treated group were significantly less than those of the control group (P < .01).

CONCLUSIONS

Systemically applied halofuginone hydrobromide decreases fibrosis/scar tissue formation secondary to experimentally induced acute subglottic trauma.