Mechanistic Rationale and Clinical Efficacy of Hyperbaric Oxygen Therapy in Chronic Neuropathic Pain: An Evidence-Based Narrative Review

Hyperbaric Oxygen Attenuates Chronic Postsurgical Pain by Regulating the CD73/Adenosine/A1R Axis of the Spinal Cord in Rats

Chronic postsurgical pain (CPSP) affects postoperative rehabilitation and quality of life in patients, but its mechanisms are still poorly understood. Hyperbaric oxygen (HBO) attenuates neuropathic pain in animal and human studies, but its efficacy for CPSP treatment and its underlying mechanism have not been elucidated. This study aimed to investigate the analgesic effect of HBO in a CPSP rat model and the role of spinal cord adenosine circulation in HBO-induced analgesia. A skin/muscle incision and retraction (SMIR) rat model was used to mimic CPSP, and HBO treatment (2.5 atmospheric absolute, 60 minutes) was administered once daily for 5 consecutive days beginning 3 days after surgery. The role of spinal cord adenosine circulation in HBO-induced analgesia was investigated using β-methylene ADP (a CD73 inhibitor), 8-cyclopentyl-1,3-dipropylxanthine (an A1R antagonist), or an intrathecal injection of adenosine. The mechanical paw withdrawal threshold was determined at different timepoints before and after surgery. The spinal cord adenosine and adenosine triphosphate (ATP) contents were analyzed using high-performance liquid chromatography, and the spinal cord expression of adenosine-1 receptor (A1R), extracellular 5'-nucleotidase (CD73), and adenosine kinase (ADK) was examined by Western blotting and immunofluorescence staining. The results showed that the mechanical paw withdrawal threshold of the ipsilateral hind paw and the adenosine content decreased, and the spinal cord expression of A1R, CD73, and ADK and ATP content increased within 14 days after surgery. HBO treatment alleviated mechanical allodynia, reduced ATP content, and increased adenosine content by activating CD73 but downregulated the spinal cord expression of A1R, CD73, and ADK. Intrathecal adenosine alleviated mechanical allodynia after SMIR and downregulated the spinal cord expression of A1R and CD73, and intrathecal β-methylene ADP or 8-cyclopentyl-1,3-dipropylxanthine attenuated the analgesic effect of HBO treatment on SMIR-induced CPSP. PERSPECTIVE: Spinal cord adenosine is involved in the occurrence and development of CPSP, and HBO treatment alleviates CPSP by regulating adenosine production/metabolism in the spinal cord. Thus, HBO may be employed for the treatment of CPSP with favorable efficacy.

The effects of hyperbaric oxygen therapy on snake-bite-associated wounds in dogs

OBJECTIVE

To assess the effect of hyperbaric oxygen therapy (HBOT) on Crotalinae envenomation-induced wound swelling and severity and pain in dogs, and to describe the safety and complications of HBOT.

DESIGN

Prospective, randomized, controlled, blinded study (2017-2021).

SETTING

University teaching hospital, private veterinary practice.

ANIMALS

Thirty-six client-owned dogs presenting within 24 hours of a confirmed or suspected naturally occurring Crotalinae snake bite injury were enrolled between 2017 and 2021.

INTERVENTIONS

In addition to the standard of care treatment, dogs received 2 interventions with either HBOT (n = 19) or control (n = 16) within 24 hours of hospital admission. Dogs receiving HBOT were pressurized over 15 minutes (1 psi/min), maintained at a target pressure of 2 atmosphere absolute (ATA) for 30 minutes, and decompressed over 15 minutes. Control dogs received 1 ATA for 1 hour. Local wound swelling, wound severity score, and pain score were assessed at admission, before and after each intervention, and at hospital discharge.

MEASUREMENTS AND MAIN RESULTS

There was no significant difference in wound swelling (P = 0.414), severity score (P = 1.000), or pain score (P = 0.689) between HBOT and control groups. Pain decreased significantly over time regardless of the study intervention (P < 0.001). There were no major adverse effects associated with either study intervention.

CONCLUSIONS

HBOT did not significantly alter the short-term recovery from Crotalinae envenomation in this study population. However, the study might be underpowered to detect a significant treatment effect.

Effects of an early intervention with Hyperbaric Oxygen Treatment on arm lymphedema and quality of life after breast cancer-an explorative clinical trial

PURPOSE

Lymphedema (LE) is a common complication after breast cancer treatment, which negatively affects the quality of life (QOL). Hyperbaric Oxygen Treatment (HBOT) is an established treatment for radiation-induced tissue injury, but evidence of effect on breast cancer-related LE is inconclusive. We aimed to explore effects of HBOT on early breast cancer-related LE and the implications for QOL.

METHODS

We invited women with breast cancer treated with surgery, axillary dissection and radiotherapy, who had participated in a randomized controlled trial and who presented with LE 1 year after surgery. In a prospective observational study design, change in LE was assessed with perometry, dual-energy X-ray absorptiometry (DXA) and lymphoscintigraphy, and QOL by validated self-report scales. Participants were offered 40 sessions of HBOT on every weekday for 8 weeks and were followed for 6 months.

RESULTS

Out of 50 eligible participants, 20 women accepted participation. Nineteen women initiated and completed treatment and follow-up. None of the objective measures of LE severity showed consistent changes during the study period, but participants reported significant improvements in QOL (physical functioning, fatigue, insomnia and breast and arm symptoms), with improvements peaking at 6-month follow-up.

CONCLUSION

Participants receiving HBOT experienced improved QOL without consistently significant changes in arm mass, volume or lymphatic drainage. These results call for studies into differential effect in patient sub-groups, and a large-scale, randomized placebo-controlled trial with long-term follow-up to assess the effect of HBOT in patients with soft tissue radiation injuries after breast cancer seems warranted.

TRIAL REGISTRATION

Danish Health and Medicines Authority, EUDRACT no. 2015-000,604-25 Ethical committee of the Capitol Region, No. R96-A6604-14-S22.

Clinical Considerations for Implanted Neurological Devices in Patients Undergoing Hyperbaric Oxygen Therapy: A Case Report and Review of Manufacturer Guidelines

Patients with implanted medical devices are increasingly referred for hyperbaric oxygen therapy (HBOT), and the safety of exposing some of these devices to hyperbaric environments has not previously been explored. There is a paucity of evidence surrounding the management of implanted neurological devices such as neurostimulators and intrathecal drug delivery (IDD) pumps in the context of HBOT. However, these devices can be expected to harbor unique risks; for example, vacant space in the reservoir of an implanted IDD pump may change in pressure and volume during the compression and decompression phases of HBOT, resulting in a damaged or dysfunctional device. We present the case of a 27-year-old woman with cerebral palsy referred for HBOT to manage a necrotizing soft tissue infection cultured from a dehiscent abdominal wound at the previous implantation site of an intrathecal baclofen pump. An HBOT protocol was ultimately chosen in partnership with the patient and her family, but treatment was not performed due to a paucity of evidence that the implanted IDD pump could safely withstand hyperbaric exposure. In this review, we have synthesized manufacturer recommendations regarding the management of implanted neurological devices before, during, and after HBOT to inform future decision-making in this setting. Among these recommendations, we highlight that neurostimulators should be switched off for the duration of HBOT and implanted pumps should be refilled prior to each treatment session to minimize empty reservoir space.

Hyperbaric oxygen therapy in low extremity trauma: A case series

Introduction

Trauma to the extremities is a common major health problem that requires special attention because it can have a dangerous impact on both the viability of the limb and the patient's life. Hyperbaric oxygen therapy is an alternative therapy hypothesized to improve the prognosis in lower extremity trauma.

Case presentation

We present a series of 7 cases of lower extremity trauma treated with hyperbaric oxygen therapy: soft tissue loss, neglected chronic burn injury, high-voltage electrical burn, gas gangrene, crush injury, chemical burn, and excoriation with skin loss.

Discussion

Hyperbaric oxygen therapy involves giving 100% oxygen in a chamber at pressures above atmospheric pressure (2–3 atm absolute [ATA]). It can increase oxygen delivery to peripheral tissues with vascular compromise, cytogenic and vasogenic edema, and cellular hypoxia caused by limb trauma.

Conclusion

Hyperbaric oxygen therapy has many benefits in lower extremity trauma for wound recovery, preventing complications, and helping patients return to daily activities.

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Hyperbaric oxygen therapy is an alternative therapy believed to improve the prognosis in cases of lower extremity trauma.

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We present 7 cases: soft tissue loss, chronic burn, high-voltage burn, gangrene, crush, chemical burn, and excoriation.

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Hyperbaric oxygen therapy has benefits for wound recovery, preventing complications, and return to daily activities.