Hyperbaric oxygen treatment: a brief overview of a controversial topic

Hyperbaric Oxygen Therapy for the Management of Mild and Moderate Traumatic Brain Injury: A Single-Center Experience

BACKGROUND

Hyperbaric oxygen therapy (HBOT) has been shown to be an effective modality in the management of a variety of conditions. However, its role in the treatment of traumatic brain injury (TBI) remains an area of controversy. This study aims to evaluate the safety and outcomes of HBOT in managing the long-term sequelae of TBI.

METHODS

The records of TBI patients who underwent increments of 40 sessions of HBOT at 1.5 atmosphere absolute at a single medical center were reviewed. The outcome measures included physical, cognitive (i.e., Trail Making Test, parts A and B; U.S. Department of Veterans Affairs' Evaluation of Cognitive Impairment and Subjective Symptoms tool), and single-photon emission computed tomography findings. The complications and withdrawals were recorded.

RESULTS

During the study period, 17 patients underwent HBOT to manage the long-term sequelae of their TBI. Of the 17 patients, 12 (70.6%) completed 120 HBOT sessions and were evaluated 3 months after treatment. All 12 patients had statistically significant improvements in their Trail Making Test, parts A and B, and U.S. Department of Veterans Affairs' Evaluation of Cognitive Impairment and Subjective Symptoms scores (P < 0.05). Additionally, single-photon emission computed tomography depicted increased cerebral blood flow and oxygen metabolism among studied subjects compared with the baseline values. A total of 5 patients withdrew from the study, which was related to new-onset headaches associated with HBOT for 1 patient.

CONCLUSIONS

HBOT using 1.5 atmosphere absolute in increments of 40 sessions was found to be a safe and effective modality in the management of the long-term sequelae of TBI. HBOT should be considered in the management of this patient population.

An overview of hyperbaric oxygen preconditioning against ischemic stroke

Ischemic stroke (IS) has become the second leading cause of morbidity and mortality worldwide, and the prevention of IS should be given high priority. Recent studies have indicated that hyperbaric oxygen preconditioning (HBO-PC) may be a protective nonpharmacological method, but its underlying mechanisms remain poorly defined. This study comprehensively reviewed the pathophysiology of IS and revealed the underlying mechanism of HBO-PC in protection against IS. The preventive effects of HBO-PC against IS may include inducing antioxidant, anti-inflammation, and anti-apoptosis capacity; activating autophagy and immune responses; upregulating heat shock proteins, hypoxia-inducible factor-1, and erythropoietin; and exerting protective effects upon the blood-brain barrier. In addition, HBO-PC may be considered a safe and effective method to prevent IS in combination with stem cell therapy. Although the benefits of HBO-PC on IS have been widely observed in recent research, the implementation of this technique is still controversial due to regimen differences. Transferring the results to clinical application needs to be taken carefully, and screening for the optimal regimen would be a daunting task. In addition, whether we should prescribe an individualized preconditioning regimen to each stroke patient needs further exploration.

An update on the current status and future prospects of erectile dysfunction following radical prostatectomy

BACKGROUND

Radical prostatectomy (RP) and radiation treatment are standard options for localized prostate cancer. Even though nerve-sparing techniques have been increasingly utilized in RP, erectile dysfunction (ED) due to neuropraxia remains a frequent complication. Erectile function recovery rates after RP remain unsatisfactory, and many men still suffer despite the availability of various therapies.

OBJECTIVE

This systematic review aims to summarize the current treatments for post-RP-ED, assess the underlying pathological mechanisms, and emphasize promising therapeutic strategies based on the evidence from basic research.

METHOD

Evaluation and review of articles on the relevant topic published between 2010 and 2021, which are indexed and listed in the PubMed database.

RESULTS

Phosphodiesterase type 5 inhibitors, intracavernosal and intraurethral injections, vacuum erection devices, pelvic muscle training, and surgical procedures are utilized for penile rehabilitation. Clinical trials evaluating the efficacy of erectogenic drugs in this setting are conflicting and far from being conclusive. The use of androgen deprivation therapy in certain scenarios after RP further exacerbates the already problematic situation and emphasizes the need for effective treatment strategies.

CONCLUSION

This article is a detailed overview focusing on the pathophysiology and mechanism of the nerve injury developed during RP and a compilation of various strategies to induce cavernous nerve regeneration to improve erectile function (EF). These strategies include stem cell therapy, gene therapy, growth factors, low-intensity extracorporeal shockwave therapy, immunophilins, and various pharmacological approaches that have induced improvements in EF in experimental models of cavernous nerve injury. Many of the mentioned strategies can improve EF following RP if transformed into clinically applicable safe, and effective techniques with reproducible outcomes.

Photoplethysmographic Waveform and Pulse Rate Variability Analysis in Hyperbaric Environments

The main aim of this work is to identify alterations in the morphology of the pulse photoplethysmogram (PPG) signal, due to the exposure of the subjects to a hyperbaric environment. Additionally, their Pulse Rate Variability (PRV) is analysed to characterise the response of their Autonomic Nervous System (ANS). To do that, 28 volunteers are introduced into a hyperbaric chamber and five sequential stages with different atmospheric pressures from 1 atm to 5 atm are performed. In this work, nineteen morphological parameters of the PPG signal are analysed: the pulse amplitude; eight parameters related to pulse width; eight parameters related to pulse area; and the two two pulse slopes. Also, classical time and frequency parameters of PRV are computed. Notable widening of the pulses width is observed in the stages analysed. The PPG area increases with pressure, with no significant changes when the initial pressure is recovered. These changes in PPG waveform may be caused by an increase in the systemic vascular resistance as a consequence of of vasoconstriction in the extremities, suggesting a sympathetic activation. However, the PRV results show an augmented parasympathetic activity and a reduction in the parameters that characterise the sympathetic response. So, only a sympathetic activation is detected in the peripheral region, as reflected by PPG morphology. The information regarding the ANS and the cardiovascular response that can be extracted from the PPG signal, as well as its compatibility with wet conditions make this signal the most suitable for studying the physiological response in hyperbaric environments.

Effect of HBO therapy on adipose-derived stem cells, fibroblasts and co-cultures: In vitro study of oxidative stress, angiogenic potential and production of pro-inflammatory growth factors in co-cultures1

BACKGROUND: A key moderator of wound healing is oxygen. Wound healing is a dynamic and carefully orchestrated process involving blood cells, cytokines, parenchymal cells (i.e. fibroblasts and mesenchymal stem cells) and extracellular matrix reorganization. Human adipose derived stem cells as well as human fibroblasts produce soluble factors, exhibit diverse effects on inflammation and anti inflammation response and are involved in wound healing processes. Hyperbaric oxygen therapy is an effective adjunct treatment for ischemic disorders such as chronic infection or chronic wounds. In vitro effects of hyperbaric oxygen therapy on human cells were presented in many studies except for those on mono- and co-cultures of human adipose derived stem cells and fibroblasts. OBJECTIVE: The aim of this study was to investigate the effects of hyperbaric oxygen therapy on mono- and co-cultures of human adipose derived stem cells and fibroblasts. METHODS: Mono- and co-cultures from human adipose derived stem cells and fibroblasts were established. These cultures were exposed to hyperbaric oxygen therapy every 24 h for five consecutive days. Measuring experiments were performed on the first, third and fifth day. Therapy effects on the expression of VEGF, IL 6 and reactive oxygen species were investigated. RESULTS: After exposure to hyperbaric oxygen, cell culturess showed a significant increase in the expression of VEGF after 3 and 5 days. All cultures showed significantly reduced formation of reactive oxygen species throughout the experiments. The expression of IL-6 decreased during the experiment in mono-cultures of human adipose derived stem cells and co-cultures. In contrast, mono-cultures of human skin fibroblasts showed an overall significantly increased expression of IL-6. CONCLUSIONS: Hyperbaric oxygen therapy leads to immunmodulatory and proangiogenetic effects in a wound-like enviroment of adipose derived stem cells and fibroblasts.

Hyperbaric Oxygen Therapy in Sports Musculoskeletal Injuries

Hyperbaric oxygen therapy (HBOT) is a well-established treatment for a variety of conditions. Hyperbaric oxygen therapy is the administration of 100% oxygen breathing in a pressure vessel at higher than atmospheric pressure (1 atmosphere absolute = 101 kPa). Typically, treatment is given daily for between 1 and 2 h at pressures of 2.0 to 2.8 ATA, depending on the indication. Sporting injuries are often treated over 3 to 10 sessions. Hyperbaric oxygen therapy has been documented to be effective and is approved in 14 medical indications by the Undersea and Hyperbaric Medical Society, including, but not limited to, carbon monoxide poisoning, compromised skin grafts and flaps, crush injuries, necrotizing soft tissue infections, and nonhealing ulcers with arterial insufficiencies. Recently, HBOT for sports musculoskeletal injuries is receiving increased attention. Hyperbaric oxygen therapy may allow injured athletes to recover faster than normal rehabilitation methods. Any reduction in collegiate and professional athletes' rehabilitation period can be financially significant for top-level sports teams; however, further research is required to confirm HBOT's benefits on sports musculoskeletal injuries. The purpose of this review to discuss the current understanding of HBOT as a treatment modality for common musculoskeletal injuries in sport medicine. Moreover, we will highlight the advantages and disadvantages of this modality, as well as relevant clinical and research applications.

Relationship of transcutaneous oxygen tension with age and skin elasticity in Korean women

BACKGROUND

Oxygen has several positive effects on the skin, including improving collagen synthesis and accelerating wound healing. However, only a few studies have investigated the relationship between skin oxygenation and skin aging parameters. Therefore, this study aimed to assess the correlation between skin oxygenation and skin aging parameters-elasticity, hydration, sebum, color (lightness, redness), and blood perfusion-in Korean women.

MATERIALS AND METHODS

We evaluated the transcutaneous partial pressure of oxygen, also known as transcutaneous oxygen tension (TcPO₂ ), and skin aging parameters, including elasticity, hydration, sebum, color (lightness or redness), and blood perfusion, in the cheek of 34 healthy women (aged 20-69 years) and assessed the correlation between TcPO₂ and other skin aging parameters using IBM SPSS Statistics 25 software (SPSS Inc).

RESULTS

Facial TcPO₂ was negatively correlated with age (P < .05). There were positive correlations between facial TcPO₂ and elasticity parameters (P < .01). We noted no correlation between facial TcPO₂ and skin lightness; however, skin lightness tended to slightly improve with increasing TcPO₂ . Skin aging parameters, including hydration, sebum, skin redness, and blood perfusion, showed no correlations with TcPO₂ .

CONCLUSION

In Korean women, facial TcPO₂ tends to decrease with increasing age and is positively correlated with gross, net, and biological skin elasticity. Therefore, this study demonstrated that oxygen tension of facial skin can be a major causative factor of skin aging.

Potential applications of topical oxygen therapy in dermatology

Background

Topical oxygen therapy is a cosmetic procedure that is becoming more and more popular in dermatology; however, only a few articles on this topic are present in the literature. In this work we report our group experience with oxygen therapy as an adjuvant treatment in various dermatological conditions.

Methods

Four studies were conducted. In the first study we used vehiculated oxygen therapy for diseases that cause hair loss. In the second study oxygen was used in the treatment of mild acne. In the third study moderate acne was treated with topical oxygen. In the fourth study chronic dermatological conditions such as psoriasis and atopic dermatitis were treated with this procedure.

Results

In studies 1 and 2 the outcomes in groups who used topical oxygen therapy as an adjuvant treatment were better than in the groups that did not use it. Studies 3 and 4 also showed very good results, but no control groups were present in the study.

Conclusion

Topical oxygen therapy was useful in the treatment of hair loss conditions, mild and moderate acne, and in chronic cutaneous diseases, showing effectiveness as a support therapy in all of these conditions. Further and larger studies should be conducted to better evaluate its effectiveness in dermatological conditions.

The Effects of Hyperbaric Oxygen Therapy on Post-Training Recovery in Jiu-Jitsu Athletes

Objectives

The present study aimed to evaluate the effects of using hyperbaric oxygen therapy during post-training recovery in jiu-jitsu athletes.

Methods

Eleven experienced Brazilian jiu-jitsu athletes were investigated during and following two training sessions of 1h30min. Using a cross-over design, the athletes were randomly assigned to passive recovery for 2 hours or to hyperbaric oxygen therapy (OHB) for the same duration. After a 7-day period, the interventions were reversed. Before, immediately after, post 2 hours and post 24 hours, blood samples were collected to examine hormone concentrations (cortisol and total testosterone) and cellular damage markers [creatine kinase (CK), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH)]. Moreover, the rating of perceived exertion (RPE) and recovery (RPR) scales were applied.

Results

Final lactate [La] values (control: 11.9 ± 1.4 mmol/L, OHB: 10.2 ± 1.4 mmol/L) and RPE [control: 14 (13–17 a.u.), OHB: 18 (17–20 a.u.)] were not significantly different following the training sessions. Furthermore, there was no difference between any time points for blood lactate and RPE in the two experimental conditions (P>0.05). There was no effect of experimental conditions on cortisol (F_1,20 = 0.1, P = 0.793, η² = 0.00, small), total testosterone (F_1,20 = 0.03, P = 0.877, η² = 0.00, small), CK (F_1,20 = 0.1, P = 0.759, η² = 0.01, small), AST (F_1,20 = 0.1, P = 0.761, η² = 0.01, small), ALT (F_1,20 = 0.0, P = 0.845, η² = 0.00, small) or LDH (F_1,20 = 0.7, P = 0.413, η² = 0.03, small). However, there was a difference between the two experimental conditions in RPR with higher values at post 2 h and 24 h in OHB when compared to the control condition (P<0.05).

Conclusions

Thus, it can be concluded that OHB exerts no influence on the recovery of hormonal status or cellular damage markers. Nonetheless, greater perceived recovery, potentially due to the placebo effect, was evident following the OHB condition.

The development of hyperbaric oxygen therapy for skin rejuvenation and treatment of photoaging

Hyperbaric oxygen therapy (HBOT), a therapy that have patients breath in pure oxygen in a pressurized chamber, has been long used as a treatment for conditions such as decompression sickness and carbon monoxide poisoning. Oxygen recently has been found to be an important component in skin rejuvenation, treatment of photoaging skin, and improvement in skin complexions. The interest in the use of HBOT for this purpose is continually growing and becoming more widespread. In addition to aging and genetic makeup, chronic UV radiation due to everyday exposure, especially UV-B, can greatly increase the rate of wrinkle formation through increasing skin angiogenesis and degradation of extracellular matrix molecules. The use of HBOT and hyperoxia conditions has been found to attenuate the formation of wrinkles from UV irradiation. It accomplishes the task by possibly inhibiting various processes and pathways involved such as the HIF1-α, VEGF, neutrophil infiltrations, and MMP-2 & MMP-9, which are directly involved with promoting skin angiogenesis in its active state. There are currently medical aesthetic clinics that are using oxygen therapy under high pressure applied directly to skin to reduce visible wrinkles but this procedure is not widespread yet due to more research that needs to be done on this topic. However, this treatment for wrinkles is definitely growing due to recent studies done showing the effectiveness of oxygen therapy on wrinkles. This review article will explore and summarize researches done on possible mechanisms dealing with the use of oxygen therapy for reduction of UVB-caused wrinkles, its side effects, and its possible future improvement and use in medicine.

Hyperbaric oxygen effects on sports injuries

In the last decade, competitive sports have taken on a whole new meaning, where intensity has increased together with the incidence of injuries to the athletes. Therefore, there is a strong need to develop better and faster treatments that allow the injured athlete to return to competition faster than with the normal course of rehabilitation, with a low risk of re-injury. Hyperbaric therapies are methods used to treat diseases or injuries using pressures higher than local atmospheric pressure inside a hyperbaric chamber. Within hyperbaric therapies, hyperbaric oxygen therapy (HBO) is the administration of pure oxygen (100%) at pressures greater than atmospheric pressure, i.e. more than 1 atmosphere absolute (ATA), for therapeutic reasons. The application of HBO for the treatment of sports injuries has recently been suggested in the scientific literature as a modality of therapy either as a primary or an adjunct treatment. Although results have proven to be promising in terms of using HBO as a treatment modality in sports-related injuries, these studies have been limited due to the small sample size, lack of blinding and randomization problems. HBO seems to be promising in the recovery of injuries for high-performance athletes; however, there is a need for larger samples, randomized, controlled, double-blinded clinical trials combined with studies using animal models so that its effects and mechanisms can be identified to confirm that it is a safe and effective therapy for the treatment of sports injuries.

Hyperbaric oxygen preconditioning promotes survival of retinal ganglion cells in a rat model of optic nerve crush

In this study we tested the hypothesis that hyperbaric oxygen preconditioning (HBO-PC) reduces retinal neuronal death due to optic nerve crush (ONC). Adult male Sprague-Dawley rats were subjected to ONC accompanied by a contralateral sham operation. HBO-PC was conducted four times by giving 100% oxygen at 2.5 atmospheres absolute (ATA) for 1 h every 12 h for 2 days prior to ONC. The rats were euthanized at 1 or 2 weeks after ONC. Retinal ganglion cell (RGC) density was counted by hematoxylin and eosin (H&E) staining of the retina and retrograde labeling with FluoroGold application to the superior colliculus. Visual function was assessed by flash visual evoked potentials (FVEP). TUNEL straining and caspase-3 and caspase-9 activity in the retinas were assessed. The RGC density in the retinas of ONC HBO-PC-treated rats was significantly higher than that of the corresponding ONC-only rats (the survival rate was 67.2% versus 49.7% by H&E staining, and 60.3% versus 28.9% by retrograde labeling with FluoroGold, respectively; p < 0.01) at 2 weeks after ONC. FVEP measurements indicated a significantly better preserved latency and amplitude of the P1 wave in the ONC HBO-PC-treated rats than the ONC-only rats (92 +/- 7 msec, 21 +/- 3 microv in the sham-operated group, 117 +/- 12 msec, 14 +/- 2 microv in the HBO-PC-treated group, and 169 +/- 15 msec, 7 +/- 1 microv in the corresponding ONC group; p < 0.01). TUNEL assays showed fewer apoptotic cells in the HBO-PC-treated group, accompanied by the suppression of caspase-3 and caspase-9 activity. These results demonstrate that HBO-PC appears to be neuroprotective against ONC insult via inhibition of neuronal apoptosis pathways.

The role of hyperbaric oxygen therapy (hot) as an otoprotection agent against cisplatin ototoxicity

PURPOSE

Hyperbaric oxygen therapy (HOT) consists of intermittent inhalations of 100% oxygen at a pressure higher than 1 atm. It is an important adjuvant therapy in pathological processes like soft tissue infections, radiation injury, gas gangrene, osteomyelitis and decompressive diseases. Cisplatin, a potent antineoplastic drug, widely used in cancer therapy is highly ototoxic causing bilateral, irreversible damage to the hearing of high frequency sounds (4-8 KHz).

OBJECTIVE

This experimental study conducted at the Faculty of Medicine of Ribeirao Preto, University of Sao Paulo aims to evaluate Hyperbaric Oxygen Therapy as an otoprotection agent against drug toxicity.

METHODS

Albino guinea pigs were divided into two groups: in Group A, 5 animals (10 cochlea) received cisplatin, i. p., 8.0 mg/kg/day during three days and afterwards were submitted to HOT; in Group B, 3 animals (6 cochlea) received cisplatin, i. p. 8.0 mg/kg/day during three days. Guinea pigs were evaluated by acoustic otoemissions (AOE) and scanning electron microscopy (SEM).

RESULTS

Group B animals showed loss of auditory functions as measured by AOE and distorted outer hair cells by SEM. In Group A, outer hair cells shown by SEM images were mostly preserved.

CONCLUSION

It is presumed that Hyperbaric Oxygen Therapy has a protector effect against cisplatin ototoxicity.

Mechanism of ischemic tolerance induced by hyperbaric oxygen preconditioning involves upregulation of hypoxia-inducible factor-1α and erythropoietin in rats

We studied the effect of hyperbaric oxygen (HBO) preconditioning on the molecular mechanisms of neuroprotection in a rat focal cerebral ischemic model. Seventy-two male Sprague-Dawley rats were pretreated with HBO (100% O2, 2 atmospheres absolute, 1 h once every other day for 5 sessions) or with room air. In experiment 1, HBO-preconditioned rats and matched room air controls were subjected to focal cerebral ischemia or sham surgery. Postinjury motor parameters and infarction volumes of HBO-preconditioned rats were compared with those of controls. In experiment 2, HBO-preconditioned rats and matched room air controls were killed at different time points. Brain levels of hypoxia-inducible factor-1α (HIF-1α) and its downstream target gene erythropoietin (EPO) analyzed by Western blotting and RT-PCR as well as HIF-1α DNA-binding and transcriptional activities were determined in the ipsilateral hemisphere. HBO induced a marked increase in the protein expressions of HIF-1α and EPO and the activity of HIF-1α, as well as the expression of EPO mRNA. HBO preconditioning dramatically improved the neurobehavioral outcome at all time points (3.0 ± 2.1 vs. 5.6 ± 1.5 at 4 h, 5.0 ± 1.8 vs. 8.8 ± 1.4 at 8 h, 6.4 ± 1.8 vs. 9.7 ± 1.3 at 24 h; P < 0.01, respectively) and reduced infarction volumes (20.7 ± 4.5 vs. 12.5 ± 3.6%, 2,3,5-Triphenyltetrazolium chloride staining) after cerebral ischemia. This observation indicates that the neuroprotection induced by HBO preconditioning may be mediated by an upregulation of HIF-1α and its target gene EPO.

Microbiology and management of joint and bone infections due to anaerobic bacteria

PURPOSE

To describes the microbiology, diagnosis, and management of septic arthritis and osteomyelitis due to anaerobic bacteria.

RESULTS

The predominant anaerobes in arthritis are anaerobic Gram-negative bacilli (AGNB) including the Bacteroides fragilis group, Fusobacterium spp., Peptostreptococcus spp., and Propionibacterium acnes. Infection with P. acnes is associated with a prosthetic joint, previous surgery, and trauma. B. fragilis group is associated with distant infection, Clostridium spp. with trauma, and Fusobacterium spp. with oropharyngeal infection. Most cases of anaerobic arthritis, in contrast to anaerobic osteomyelitis, involved a single isolate, and most cases are secondary to hematogenous spread. The predominant anaerobes in osteomyelitis are Bacteroides, Peptostreptococcus, Fusobacterium, and Clostridium spp. as well as P. acnes. Conditions predisposing to bone infections are vascular disease, bites, contiguous infection, peripheral neuropathy, hematogenous spread, and trauma. Pigmented Prevotella and Porphyromonas spp. are mostly isolated in skull and bite infections, members of the B. fragilis group in hand and feet infections, and Fusobacterium spp. in skull, bite, and hematogenous long bone infections. Many patients with osteomyelitis due to anaerobic bacteria have evidence of an anaerobic infection elsewhere in the body that is the source of the organisms involved in the osteomyelitis. Treatment of arthritis and osteomyelitis involving anaerobic bacteria includes symptomatic therapy, immobilization in some cases, adequate drainage of purulent material, and antibiotic therapy effective against these organisms.

CONCLUSIONS

Anaerobic bacteria can cause septic arthritis and osteomyelitis. Correct diagnosis and appropriate therapy are important contributor to successful outcome.

Potential effects of hyperbaric oxygen therapy in acute pancreatitis

BACKGROUND

To extract from the biomedical published reports, the effects of hyperbaric oxygen (HBO) on inflammatory disease, in particular acute pancreatitis.

METHODS

This review will explain these effects and evaluate potential mechanisms of action of HBO in acute pancreatitis. A Medline/PubMed search (January 1966 to July 2004) with manual cross-referencing was conducted, including all relevant articles investigating the molecular and systemic effects of HBO on inflammatory diseases, particularly focusing on the studies of acute pancreatitis. All publication types, languages and subsets were searched.

RESULTS

Original and review articles and short communications were extracted. The selected original articles covered the molecular and systemic effects of HBO and the effects in inflammatory disease states. The major findings are that HBO can act as an anti-inflammatory agent and as an antimicrobial agent. Many of the effects of HBO would be beneficial in the treatment of acute severe pancreatitis. Work carried out to date in animal models of acute pancreatitis shows promising improvements in severity but studies are limited to date.

CONCLUSION

Acute pancreatitis impairs the pancreatic and systemic microcirculation and causes acute inflammation. These processes are potentially improved by HBO therapy.

Effect of hyperbaric oxygen on cardiac neural regulation in diabetic individuals with foot complications

AIMS

There are relatively few effective methods to treat autonomic neuropathy in patients with diabetes mellitus. Our aim was to test the hypothesis that hyperbaric oxygen therapy may restore cardiac neural regulation dysfunction in diabetic individuals with foot complications.

METHODS

We conducted a prospective randomized controlled study in patients with diabetic foot problems. Daily heart-rate variability analysis from 5-min electrocardiography was used to evaluate the temporal change of cardiac neural regulation. The experimental group consisted of 23 subjects exposed to hyperbaric oxygen therapy of 202.65 kPa for 90 min every Monday to Friday for 4 weeks (20 treatments). The control group consisted of 15 age-, sex- and disease-matched subjects who were not exposed to hyperbaric therapy. Patients with medical complications and failure of wound healing were excluded to eliminate possible confounding effects.

RESULTS

There was no significant difference in baseline R-R interval (RR), variance, high-frequency power (HF), low-frequency power (LF), and LF/HF ratio between the two groups. In the hyperbaric oxygen group there were significant increases in changes of RR (82.7 +/- 16.02 ms); variance 0.88 +/- 0.12 ln(ms2); HF 1.06 +/- 0.18 ln(ms2); and LF 0.87 +/- 0.15 ln(ms2) after the treatment. Measurements of tissue oxygen demonstrated significant increases in local tissue oxygenation in the hyperbaric oxygen group (53.0 +/- 2.6 mmHg) compared with the control group (27.5 +/- 3.1 mmHg), P < 0.05.

CONCLUSION

Hyperbaric oxygen therapy has a significant vagotonic effect, which is beneficial in improving cardiac neural regulation in patients with diabetic autonomic dysfunction.

Adjuvant Hyperbaric Oxygen Therapy in the Management of Crush Injury and Traumatic Ischemia: An Evidence-Based Approach

Hyperbaric oxygen therapy (HBO) has been recommended as an adjunct treatment in acute traumatic ischemia and crush injury. Several animal models have shown better outcomes when HBO is used in crush injury and compartment syndrome. Animal and in vitro models have suggested that these beneficial effects may be mediated by attenuation of ischemia-reperfusion injury. We did a systematic review of the literature using the Eastern Association for the Surgery of Trauma (EAST) recommendations for evidence-based reviews. An electronic search using Medline, OVID technologies, and the Cochrane database was performed. Only clinical papers published between 1966 and December 2003 with at least five patients that included enough information to evaluate were selected. A group of trauma experts reviewed the selected articles and scored them applying the instrument developed by the EAST practice management guidelines committee. Nine documents fulfilled the inclusion criteria for a total of approximately 150 patients. Most documents were retrospective, uncontrolled, and case series lacking a standardized methodology (class III). There was one prospective controlled randomized trial with some limitations on its design. We determined that eight of nine studies showed a beneficial effect from HBO with only one major complication. We concluded that adjunctive HBO is not likely to be harmful and could be beneficial if administered early. Well designed clinical studies are warranted.

Effect of hyperbaric oxygen on the growth factor profile of fibroblasts

OBJECTIVES

Hyperbaric oxygen (HBO) has been used in the clinical setting to heal problem wounds, yet its direct effects on fibroblasts are not clear. The present study evaluates the effects of HBO on the growth and autocrine production of growth factors by fibroblasts grown in an in vitro, serum-free environment.

METHODS

Human dermal fibroblasts were propagated in serum-free media and subjected to daily 90-minute HBO treatments at 1.0, 1.5, 2.0, 2.5, and 3.0 atm of pressure for 7 consecutive days. Cell proliferation and growth-factor assays for basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and transforming growth factor beta1 (TGF-beta1) were performed on days 1, 3, 5, and 7.

RESULTS

On day 1, HBO inhibited growth of fibroblasts at all atmospheric pressures compared with control. By day 7, cell proliferation was significantly enhanced only in cells treated with 2.0-atm HBO compared with controls. Secretion of bFGF was significantly increased by HBO-treated fibroblasts on day 1; VEGF levels slightly increased with HBO treatment on day 1, but this effect was not statistically significant; TGF-beta1 levels were detectable on day 1 only for control and HBO-treated cells at 1.0 atm, and not detectable for any cell groups after day 1.

CONCLUSIONS

These results suggest that daily HBO treatment enhances the growth of fibroblasts when administered to a critical degree. Also, HBO appears to directly effect fibroblast production of autocrine growth factors on initial exposure. We postulate that fibroblasts possess the ability to respond to hyperoxia directly, which causes changes in cell signaling pathways involved in cellular proliferation and growth factor production.

Investigation of pulmonary epithelial permeability in patients after hyperbaric oxygen therapy by 99mTc diethylenetriaminepentaacetic acid aerosol inhalation lung scintigraphy

The aim of this study was to evaluate the possibility of pulmonary epithelial permeability damage in patients after hyperbaric oxygen therapy (HBOT) by 99mTc diethylenetriaminepentaacetic acid (99mTc-DTPA) aerosol inhalation lung scintigraphy. Twenty-five controls and 21 patients with normal chest X-rays and no cigarette smoking for at least 1 year were recruited for the study. 99mTc-DTPA aerosol inhalation lung scans were performed after 20 HBOT sessions in 21 patients with refractory osteomyelitis or diabetic foot. The HBOT with 100% oxygen at 2.5 atm absolute for 100 min was performed five times a week. Clearance rates (%/min) of 99mTc-DTPA aerosol in each lung field were calculated from the dynamic images for 30 min. Clearance rates of 99mTc-DTPA aerosol were compared between patients and controls by the unpaired t test. Thirteen patients who had 99mTc-DTPA aerosol lung scans before and after HBOT therapy studies were tested for statistical significance by using the paired t test. There was no statistically significant difference (P>0.05, unpaired t test) between patients and controls in every lung field. For the 13 patients who had 99mTc-DTPA aerosol studies both before and after 20 HBOT sessions, the results also showed no statistically significant difference (P>0.05, paired t test). It is concluded that there was no demonstrable pulmonary epithelial permeability change under current clinical HBOT protocol.

Hyperbaric medicine in soft tissue trauma

Severe crush injuries of the soft tissues can result in tears of the large vessels and destruction of the microcirculation. This produces ischaemia and tissue necrosis and contributes to the development of oedema and compartment syndromes. All these factors compromise tissue survival. Immediately following a crush injury some areas of tissue are obviously irreversibly damaged, and others undamaged. It is common to have a ‘grey area’ between these, where there is uncertainty as to what will survive. Management of crush injury must involve surgical repair of vessels and soft tissues, debridement of obviously dead tissue, and bone stabilization. At the same time tissue perfusion must be maintained by manoeuvres such as fluid replacement and diminution of oedema, and when necessary fasciotomy. It has been proposed that hyperbaric oxygen therapy has a role, as an adjunct, in the maintenance of tissue oxygenation under these conditions, and will improve survival of tissues in the grey area, and thus minimize tissue loss. Hyperbaric oxygen therapy involves breathing 100% oxygen at pressures greater than one atmosphere. Presently, the pressures most often used are in the range 2-3 atmospheres absolute.