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Bispectral index with density spectral array (BIS-DSA) monitoring during hyperbaric oxygen therapy of a case with inner ear and cerebral decompression sickness is described. During the initial treatment, a particular DSA pattern was found, which resolved after four treatments. Clinical resolution of the symptoms accompanied this improvement. The particular BIS-DSA pattern described in this case is concordant with a potential hypo-perfusion of the cortex related to decompression stress. This case suggests that BIS-DSA monitoring may be an easy, cost-effective, and viable form of neuro-monitoring during hyperbaric oxygen treatment for decompression sickness. [ABSTRACT FROM AUTHOR]

Introduction: The stability of a new hyperbaric ventilator (Shangrila590, Beijing Aeonmed Company, Beijing, China) at different clinically relevant pressures in a hyperbaric chamber during pressure-controlled ventilation (PCV) was investigated. Methods: The ventilator was connected to a test lung in the multiplace hyperbaric chamber. The inspiratory pressure (PI) of the ventilator was set to 1.0, 1.5, 2.0, 2.5 and 3.0 kPa (approximately 10, 15, 20, 25 and 30 cmH2O). The compliance and resistance of the test lung were set to 200 mL·kPa-1 and 2 kPa·L-1·s-1, respectively. Experiments were conducted at 101, 203 and 284 kPa ambient pressure (1.0, 2.0 and 2.8 atmospheres absolute respectively). At each of the 5 PI values, the tidal volume (VT), peak inspiratory pressure (Ppeak) and peak inspiratory flow (Fpeak) displayed by the ventilator and the test lung were recorded for 20 cycles. Test lung data were considered the actual ventilation values. The ventilation data were compared among the three groups to evaluate the stability of the ventilator. Results: At every PI, the Ppeak detected by the ventilator decreased slightly with increasing ambient pressure. The Fpeak values measured by the test lung decreased substantially as the ambient pressure increased. Nevertheless, the reduction in VT at 284 kPa and PI 30 cmH2O (compared to performance at 101 kPa) was comparatively small (approximately 60 ml). Conclusions: In PCV mode this ventilator provided relatively stable VT across clinically relevant PI values to ambient pressures as high as 284 kPa. However, because Fpeak decreases at higher ambient pressure, some user adjustment might be necessary for precise VT maintenance during clinical use at higher PIs and ambient pressures. [ABSTRACT FROM AUTHOR]

Introduction: This study analysed treatment outcomes in a patient cohort diagnosed with spondylodiscitis, who received adjunct hyperbaric oxygen treatment (HBOT) in addition to antibiotic therapy at our clinic. Important considerations included the timing of HBOT initiation on treatment success, and recurrence rates. Methods: We retrospectively reviewed the records of all patients diagnosed with spondylodiscitis who received HBOT at the Underwater and Hyperbaric Medicine Clinic in Gulhane Training and Research Hospital, between 1 November 2016 and 25 October 2022. The patients received HBOT at 243.2 kPa for a total of 120 minutes per session, once daily for five days a week for a total of 30 sessions. Results: Twenty-five patients with spondylodiscitis were evaluated before and after combination HBOT and targeted antibiotic treatment. After treatment, patients had lower median (range) visual analogue pain scores (8 [4-10] vs 3 [0-7], P < 0.001) and C-reactive protein (22.3 [4.3-79.9] mg·L-1 vs 6.8 [0.1-96.0] mg·L-1, P = 0.002) and lower mean (standard deviation) white blood cell counts (8.8 [3.5] x 109·L-1 vs 6.1 [1.6] x 109·L-1, P = 0.002). When patients were examined (median) 48 months (2-156 months) after the completion of treatment, there were no persistent cases of spondylodiscitis. Conclusions: Combination HBOT with targeted antibiotic therapy effectively managed our cohort of patients diagnosed with spondylodiscitis. Hyperbaric oxygen treatment was safe, with no complications experienced. Moreover, HBOT may have helped to eliminate persistence and recurrence of symptoms with long term follow-up. A randomised controlled study with a larger number of patients is needed for more definitive conclusions. [ABSTRACT FROM AUTHOR]

Hyperbaric oxygen treatment (HBOT) can be utilised for necrotising soft tissue infections, clostridial myonecrosis (gas gangrene), crush injuries, acute traumatic ischaemia, delayed wound healing, and compromised skin grafts. Our case was a 17-month-old male patient with Noonan syndrome, idiopathic thrombocytopenic purpura, and bilateral undescended testicles. Haematoma and oedema developed in the scrotum and penis the day after bilateral orchiopexy and circumcision. Ischaemic appearances were observed on the penile and scrotal skin on the second postoperative day. Enoxaparin sodium and fresh frozen plasma were started on the recommendation of haematology. Hyperbaric oxygen treatment was initiated considering the possibility of tissue necrosis. We observed rapid healing within five days. We present this case to emphasise that HBOT may be considered as an additional treatment option in patients with similar conditions. To our knowledge, no similar cases have been reported in the literature. [ABSTRACT FROM AUTHOR]

Cardiac complications are a rare but potentially serious consequence of hyperbaric oxygen treatment (HBOT), resulting from increased blood pressure and decreased heart rate and cardiac output associated with treatment. These physiologic changes are generally well-tolerated by patients without preexisting cardiac conditions, although those with known or undetected cardiac disease may be more vulnerable to treatment complications. Currently, there are no universally accepted guidelines for pre-HBOT cardiac screening to identify these patients at heightened risk, leading to variability in practice patterns. In the absence of HBOT-specific evidence, screening protocols might be adapted from the diving medicine community; however, given the important differences in physiological stressors, these may not be entirely applicable to patients undergoing HBOT. Traditional cardiac investigations such as electro- and echo-cardiograms are limited in their ability to detect relevant risk modifying states in the pre-HBOT patient, stymieing their cost-effectiveness as routine tests. In the absence of strong evidence to support routine cardiac investigation, we argue that a comprehensive history and physical exam - tailored to identify high-risk patients based on clinical parameters - may serve as a more practical screening tool. While certain unique patient groups such as those undergoing dialysis or with implanted cardiac devices may warrant specialised assessment, thorough evaluation may be sufficient to identify many patients unlikely to benefit from cardiac investigation in the pre- HBOT setting. A clinical decision-making tool based on suggested low-risk and high-risk features is offered to guide the use of targeted cardiac investigation prior to HBOT. [ABSTRACT FROM AUTHOR]

Introduction: Avascular necrosis (AVN) is a rare progressive degenerative disease leading to bone and joint destruction. Patients often require surgical intervention. Femoral AVN is the most common anatomical location. Hyperbaric oxygen treatment (HBOT) has been shown to be effective in AVN. We present data collected from one centre over a 30-year period and compare the results with other published data. Methods: A retrospective chart review of all patients receiving HBOT for AVN at Fremantle and Fiona Stanley Hospitals since 1989 was performed. The primary outcome was radiological appearance using the Steinberg score, with secondary outcomes being subjective improvement, the need for joint replacement surgery and rates of complications. Results: Twenty-one joints in 14 patients (14 femoral heads and seven femoral condyles) were treated with HBOT since 1989. Two patients were excluded. Within the femoral head group, nine of the 14 joints (64%) had stable or improved magnetic resonance imaging (MRI) scans post treatment and at six months (minimum); 10 joints (71%) had good outcomes subjectively, three joints required surgical intervention, and three patients developed mild aural barotrauma. Within the femoral condyle group, all five joints had stable or improved post-treatment MRI scans (four had visible improvement in oedema and/or chondral stability), four joints reported good outcomes subjectively, none of the patients required surgical intervention (follow-up > six months). Conclusions: This single centre retrospective study observed prevention of disease progression in femoral AVN with the use of HBOT, comparable to other published studies. This adds to the body of evidence that HBOT may have a significant role in the treatment of femoral AVN. [ABSTRACT FROM AUTHOR]

Introduction: Central retinal artery occlusion (CRAO) presents suddenly causing painless loss of vision that is often significant. Meaningful improvement in vision occurs in only 8% of patients with spontaneous reperfusion. Hyperbaric oxygen treatment (HBOT) is considered to be of benefit if commenced before retinal infarction occurs. The Undersea and Hyperbaric Medical Society (UHMS) guidelines on the management of CRAO were last amended in 2019. This survey questioned Australian and New Zealand (ANZ) hyperbaric medicine units (HMUs) about the incidence of CRAO cases referred and compared their subsequent management against the UHMS guidelines. Methods: An anonymous survey via SurveyMonkey® was sent to all 12 ANZ HMUs that treat emergency indications, allowing for multiple choice and free text answers regarding their management of CRAO. Results: One-hundred and forty-six cases of CRAO were treated in ANZ HMUs over the last five years. Most (101/146) cases (69%) were initially treated at a pressure of 284 kPa. This was the area of greatest difference noted in CRAO management between the UHMS guidelines and ANZ practice. Conclusions: Few ANZ HMUs strictly followed the UHMS guidelines. We suggest a more simplified management protocol as used by the majority of ANZ HMUs. [ABSTRACT FROM AUTHOR]

Cricoid chondronecrosis is a rare entity and is scarcely reported in the literature. Its prevalence is increasing in the form of chondroradionecrosis among the survivorship of head and neck carcinoma patients treated with radiotherapy. We have reported a case of cricoid chondronecroisis caused by trauma from repeated tracheostomy. The patient presented with hoarseness and dyspnoea. Radiological findings in multidetector computed tomography showed disintegration of the cricoid and confirmed the diagnosis. Conservative treatment was given in the form of antibiotics, steroids and nebulised anticholinergics and bronchodilators. However, the patient did not improve and his condition worsened throughout two months of hospitalisation. He was referred for hyperbaric oxygen treatment, which was given over 30 sessions. This was associated with improvement in his condition and he was able to be decannulated from tracheostomy. Six monthly follow up of the patient showed a well-healed tracheostomy scar. [ABSTRACT FROM AUTHOR]

Introduction: Hyperbaric oxygen treatment (HBOT) remains a recognised treatment for acute carbon monoxide (CO) poisoning, but the utility of HBOT in treating CO-induced delayed neurological sequelae (DNS) is not yet established. Case description: A 26-year old woman presented with reduced consciousness secondary to CO exposure from burning charcoal. She underwent a single session of HBOT with US Navy Treatment Table 5 within six hours of presentation, with full neurological recovery. Eight weeks later, she represented with progressive, debilitating neurological symptoms mimicking Parkinsonism. Magnetic resonance imaging of her brain demonstrated changes consistent with hypoxic ischaemic encephalopathy. The patient underwent 20 sessions of HBOT at 203 kPa (2 atmospheres absolute) for 115 minutes, and received intravenous methylprednisolone 1 g per day for three days. The patient's neurological symptoms completely resolved, and she returned to full-time professional work with no further recurrence. Discussion: Delayed neurological sequelae is a well-described complication of CO poisoning. In this case, the patient's debilitating neurocognitive symptoms resolved following HBOT. Existing literature on treatment of CO-induced DNS with HBOT consists mainly of small-scale studies and case reports, many of which similarly suggest that HBOT is effective in treating this complication. However, a large, randomised trial is required to adequately determine the effectiveness of HBOT in the treatment of CO-induced DNS, and an optimal treatment protocol. [ABSTRACT FROM AUTHOR]

Introduction: Hyperbaric oxygen treatment (HBOT) is recommended for arterial gas embolism (AGE) with severe symptoms. However, once symptoms subside, there may be a dilemma to treat or not. Case presentation: A 71-year-old man was noted to have a mass shadow in his left lung, and a transbronchial biopsy was performed with sedation. Flumazenil was intravenously administered at the end of the procedure. However, the patient remained comatose and developed bradycardia, hypotension, and ST-segment elevation in lead II. Although the ST changes spontaneously resolved, the patient had prolonged disorientation. Whole-body computed tomography revealed several black rounded lucencies in the left ventricle and brain, confirming AGE. The patient received oxygen and remained supine. His neurological symptoms gradually improved but worsened again, necessitating HBOT. HBOT was performed seven times, after which neurological symptoms resolved almost completely. Conclusions: AGE can secondarily deteriorate after symptoms have subsided. We recommend that HBOT be performed promptly once severe symptoms appear, even if they resolve spontaneously. [ABSTRACT FROM AUTHOR]

A proposal for a large, multi-centre, randomised controlled trial investigating the role of hyperbaric oxygen treatment (HBOT) in necrotising soft tissue infections (NSTI) has led to much discussion locally and internationally about whether participation is ethical for a centre where stakeholders already consider HBOT standard practice. This article systematically addresses the concept of clinical equipoise specific to the role of HBOT in NSTI, and presents a series of considerations to be taken into account by key stakeholders at potential participating sites. [ABSTRACT FROM AUTHOR]

Introduction: There are inconsistencies in outcome reporting for patients with necrotising soft tissue infections (NSTI). The aim of this study was to evaluate reported outcome measures in NSTI literature that could inform a core outcome set (COS) such as could be used in a study of hyperbaric oxygen in this indication. Methods: A systematic review of all NSTI literature identified from Cochrane, Ovid MEDLINE and Scopus databases as well as grey literature sources OpenGrey and the New York Academy of Medicine databases which met inclusion criteria and were published between 2010 and 2020 was performed. Studies were included if they reported on > 5 cases and presented clinical endpoints, patient related outcomes, or resource utilisation in NSTI patients. Studies did not have to include intervention. Two independent researchers then extracted reported outcome measures. Similar outcomes were grouped and classified into domains to produce a structured inventory. An attempt was made to identify trends in outcome measures over time and by study design. Results: Three hundred and seventy-five studies were identified and included a total of 311 outcome measures. Forty eight percent (150/311) of outcome measures were reported by two or more studies. The four most frequently reported outcome measures were mortality without time specified, length of hospital stay, amputation performed, and number of debridements, reported in 298 (79.5%), 260 (69.3%), 156 (41.6%) and 151 (40.3%) studies respectively. Mortality outcomes were reported in 23 different ways. Randomised controlled trials (RCTs) were more likely to report 28-day mortality or 90-day mortality. The second most frequent amputation related outcome was level of amputation, reported in 7.5% (28/375) of studies. The most commonly reported patient-centred outcome was the SF-36 which was reported in 1.6% (6/375) of all studies and in 2/10 RCTs. Conclusions: There was wide variance in outcome measures in NSTI studies, further highlighting the need for a COS. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to investigate whether hyperbaric oxygen treatment (HBOT) could ameliorate ischaemiareperfusion injury in a rat model of ovarian torsion-detorsion. Methods: Twenty-seven rats were divided among four groups: surgical sham rats (S) (n = 6) underwent identical anaesthesia and surgical incisions to other groups (n = 7 per group) but with no ovary intervention; torsion rats (T) underwent laparotomy, ovarian torsion, relaparotomy and sacrifice after three hours; torsion and detorsion rats (T/DT) underwent laparotomy, ovarian torsion (three hours), relaparotomy and detorsion, and sacrifice after one week; torsion, detorsion, hyperbaric oxygen rats (T/DT/HBOT) underwent laparotomy, ovarian torsion, relaparotomy and detorsion, and sacrifice after one week during which HBOT was provided 21 times (100% oxygen at 600 kPa for 50 min). In all groups blood collection for markers of oxidative stress or related responses, and ovary collection for histology were performed after sacrifice. Results: When the T/DT, and T/DT/HBOT groups were compared, 8-hydroxy-2'-deoxyguanosine (a marker of oxidative damage to DNA) and malondialdehyde (a product of lipid peroxidation) levels were lower in the T/DT/HBOT group. Anti-Mullerian hormone levels were higher in the T/DT/HBOT group compared to the T/DT group. In addition, oedema, vascular occlusion, neutrophilic infiltration and follicular cell damage were less in the T/DT/HBOT group than in the T/DT group. Conclusions: When biochemical and histopathological findings were evaluated together, HBOT appeared reduce ovarian ischaemia / reperfusion injury in this rat model of ovarian torsion-detorsion. [ABSTRACT FROM AUTHOR]

Introduction: Literature searches are routinely used by researchers for conducting systematic reviews as well as by healthcare providers, and sometimes patients, to quickly guide their clinical decisions. Using more than one database is generally recommended but may not always be necessary for some fields. This study aimed to determine the added value of searching additional databases beyond MEDLINE when conducting a literature search of hyperbaric oxygen treatment (HBOT) randomised controlled trials (RCTs). Methods: This study consisted of two phases: a scoping review of all RCTs in the field of HBOT, followed by a a statistical analysis of sensitivity, precision, 'number needed to read' (NNR) and 'number unique' included by individual biomedical databases. MEDLINE, Embase, Cochrane Central Register of Control Trials (CENTRAL), and Cumulated Index to Nursing and Allied Health Literature (CINAHL) were searched without date or language restrictions up to December 31, 2022. Screening and data extraction were conducted in duplicate by pairs of independent reviewers. RCTs were included if they involved human subjects and HBOT was offered either on its own or in combination with other treatments. Results: Out of 5,840 different citations identified, 367 were included for analysis. CENTRAL was the most sensitive (87.2%) and had the most unique references (7.1%). MEDLINE had the highest precision (23.8%) and optimal NNR (four). Among included references, 14.2% were unique to a single database. Conclusions: Systematic reviews of RCTs in HBOT should always utilise multiple databases, which at minimum include MEDLINE, Embase, CENTRAL and CINAHL. [ABSTRACT FROM AUTHOR]

Introduction: We aimed to analyse the outcomes of hyperbaric oxygen treatment (HBOT) and describe difficulties encountered in infants, a rare patient population in this therapeutic intervention, with limited scientific reports. Methods: This was a retrospective analysis of patients 12 months old or younger who underwent HBOT in two different institutions. Demographic data, clinical presentation, HBOT indication, chamber type, oxygen delivery method, total number of treatments, outcome and complications were extracted from clinical records. Results: There were 54 infants in our study. The patients' median age was 3.5 (range 0-12) months. The major HBOT indication was acute carbon monoxide intoxication (n = 32). A total of 275 HBOT treatments were administered, mostly performed in multiplace chambers (n = 196, 71%). Only one patient (2%) required mechanical ventilation. Acute signs were fully resolved in the most patients (n = 40, 74%). No complications related to HBOT were reported. Conclusions: This study suggests that HBOT may be a safe and effective treatment for infants. Paediatricians should consider HBOT when indicated in infants even for the preterm age group. [ABSTRACT FROM AUTHOR]

Delayed post-hypoxic encephalopathy can occur after an episode of anoxia or hypoxia. Symptoms include apathy, confusion, and neurological deficits. We describe a 47-year-old male patient who inhaled gas from a kitchen stove liquid petroleum gas cylinder. He was diagnosed with hypoxic ischaemic encephalopathy 12 hours after his emergency department admission. He received six sessions of hyperbaric oxygen treatment (HBOT) and was discharged in a healthy state after six days. Fifteen days later, he experienced weakness, loss of appetite, forgetfulness, depression, balance problems, and inability to perform self-care. One week later, he developed urinary and fecal incontinence and was diagnosed with post-hypoxic encephalopathy. After 45 days from the onset of symptoms, he was referred to the Underwater and Hyperbaric Medicine Department for HBOT. The patient exhibited poor self-care and slow speech rate, as well as ataxic gait and dysdiadochokinesia. Hyperbaric oxygen was administered for twenty-four sessions, which significantly improved the patient's neurological status with only hypoesthesia in the left hand remaining at the end of treatment. Hyperbaric oxygen has been reported as successful in treating some cases of delayed neurological sequelae following CO intoxication. It is possible that HBO therapy may also be effective in delayed post-hypoxic encephalopathy from other causes. This may be achieved through mechanisms such as transfer of functional mitochondria to the injury site, remyelination of damaged neurons, angiogenesis and neurogenesis, production of anti-inflammatory cytokines, and balancing of inflammatory and anti-inflammatory cytokines. [ABSTRACT FROM AUTHOR]

Introduction: While gas narcosis is familiar to most divers conducting deep (> 30 metres) dives, its effects are often considered minuscule or subtle at 30 metres. However, previous studies have shown that narcosis may affect divers at depths usually considered safe from its influence, but little knowledge exists on the effects of gas narcosis on higher cognitive functions such as decision-making in relatively shallow water at 30 metres. Impaired decision-making could be a significant safety issue for a multitasking diver. Methods: We conducted a study exploring the effects of gas narcosis on decision-making in divers breathing compressed air underwater. The divers (n = 22) were evenly divided into 5-metre and 30-metre groups. In the water, we used underwater tablets equipped with the Iowa Gambling Task (IGT), a well-known psychological task used to evaluate impairment in decision-making. Results: The divers at 30 metres achieved a lower score (mean 1,584.5, standard deviation 436.7) in the IGT than the divers at 5 metres (mean 2,062.5, standard deviation 584.1). Age, body mass index, gender, or the number of previous dives did not affect performance in the IGT. Conclusions: Our results suggest that gas narcosis may affect decision-making in scuba divers at 30 metres depth. This supports previous studies showing that gas narcosis is present at relatively shallow depths and shows that it may affect higher cognitive functions. [ABSTRACT FROM AUTHOR]

Introduction: To develop the diving capacity in the Swedish armed forces the current air decompression tables are under revision. A new decompression table named SWEN21 has been created to have a projected risk level of 1% for decompression sickness (DCS) at the no stop limits. The aim of this study was to evaluate the safety of SWEN21 through the measurement of venous gas emboli (VGE) in a dive series. Methods: A total 154 dives were conducted by 47 divers in a hyperbaric wet chamber. As a proxy for DCS risk, serial VGE measurements by echocardiography were conducted and graded according to the Eftedal-Brubakk scale. Measurements were made every 15 minutes for approximately 2 hours after each dive. Peak VGE grades for the different dive profiles were used in a Bayesian approach correlating VGE grade and risk of DCS. Symptoms of DCS were continually monitored. Results: The median (interquartile range) peak VGE grade after limb flexion for a majority of the time-depth combinations, and of SWEN21 as a whole, was 3 (3-4) with the exception of two decompression profiles which resulted in a grade of 3.5 (3-4) and 4 (4-4) respectively. The estimated risk of DCS in the Bayesian model varied between 4.7-11.1%. Three dives (2%) resulted in DCS. All symptoms resolved with hyperbaric oxygen treatment. Conclusions: This evaluation of the SWEN21 decompression table, using bubble formation measured with echocardiography, suggests that the risk of DCS may be higher than the projected 1%. [ABSTRACT FROM AUTHOR]

Introduction: There is clinical equipoise as to whether hyperoxia is injurious to the myocardium, both in the setting of acute ischaemic insults and on the stable myocardium. This study examined the effect of extreme hyperoxia - in the form of hyperbaric oxygen treatment - on the myocardium through measurement of high-sensitivity cardiac troponin. Methods: Forty-eight individuals were enrolled to undergo a series of 30 exposures to hyperbaric oxygen for treatment of non-cardiac pathologies. High-sensitivity troponin T was measured before and after each session. Results: There was no clinically significant difference in troponin measurements following acute or recurrent sequential exposures to extreme hyperoxia, despite the studied patient population having a high rate of previous ischaemic heart disease or cardiovascular risk factors. Conclusions: This study demonstrates that profound hyperoxaemia does not induce any measurable cardiac injury at a biochemical level. Neither is there a reduction in cardiac troponin to suggest a cardioprotective effect of hyperbaric hyperoxia. This provides some reassurance as to the cardiac safety of the routine use of hyperbaric oxygen treatment in management of non-cardiac pathology. [ABSTRACT FROM AUTHOR]

Introduction: Inner ear decompression sickness (IEDCS) is increasingly recognised in recreational diving, with the inner ear particularly vulnerable to decompression sickness in divers with a right-to-left shunt, such as is possible through a persistent (patent) foramen ovale (PFO). A review of patients treated for IEDCS at Fiona Stanley Hospital Hyperbaric Medicine Unit (FSH HMU) in Western Australia was performed to examine the epidemiology, risk factors for developing this condition, the treatment administered and the outcomes of this patient population. Methods: A retrospective review of all divers treated for IEDCS from the opening of the FSH HMU on 17 November 2014 to 31 December 2020 was performed. Patients were included if presenting with vestibular or cochlear dysfunction within 24 hours of surfacing from a dive, and excluded if demonstrating features of inner ear barotrauma. Results: There were a total of 23 IEDCS patients and 24 cases of IEDCS included for analysis, with 88% experiencing vestibular manifestations and 38% cochlear. Median dive time was 40 minutes and median maximum depth was 24.5 metres. The median time from surfacing to hyperbaric oxygen treatment (HBOT) was 22 hours. Vestibulocochlear symptoms fully resolved in 67% and complete symptom recovery was achieved in 58%. A PFO was found in 6 of 10 patients who subsequently underwent investigation with bubble contrast echocardiography upon follow-up. Conclusions: IEDCS occurred predominantly after non-technical repetitive air dives and ongoing symptoms and signs were often observed after HBOT. Appropriate follow-up is required given the high prevalence of PFO in these patients. [ABSTRACT FROM AUTHOR]

Introduction: Blood glucose levels may be influenced by hyperbaric oxygen treatment (HBOT). Patients with diabetes mellitus commonly receive HBOT but there is a lack of standardised blood glucose management guidelines. We documented relevant contemporary practices applied for patients with diabetes treated in hyperbaric medicine units. Methods: A survey was administered in 2022 to the directors of all 13 accredited hyperbaric units in Australia and New Zealand to identify policies and practices related to management of patients with diabetes receiving HBOT. Results: Twelve of the 13 units routinely managed patients with diabetes. Three-quarters (9/12) used < 4 mmol·l-1 as their definition of hypoglycaemia, whereas the other three used < 5, < 3.6, and < 3 mmol·l-1. Units reported 26% (range 13-66%) of their patients have a diagnosis of diabetes of which 93% are type 2. Ten (83%) units reported specific written protocols for managing blood glucose. Protocols were more likely to be followed by nursing (73%) than medical staff (45%). Ten (83%) units routinely tested blood glucose levels on all patients with diabetes. Preferred pre-treatment values for treatments in both multiplace and monoplace chambers ranged from = 4 to = 8 mmol·l-1. Seven (58%) units reported continuation of routine testing throughout a treatment course with five (42%) units having criteria-based rules for discontinuing testing for stable patients over multiple treatments. Two-thirds of units were satisfied with their current policy. Conclusions: This survey highlights the burden of diabetes on patients treated with HBOT and identifies considerable variability in practices which may benefit from further study to optimise management of these patients. [ABSTRACT FROM AUTHOR]

Introduction: This study analysed the treatment outcomes of patients that received hyperbaric oxygen treatment (HBOT) for retinal artery occlusion (RAO) at the Royal Brisbane and Women's Hospital in Brisbane, Australia between 2015 and 2021. Methods: Retrospective study from patient records including 22 eyes from 22 patients that received HBOT for either central RAO (17 patients) or branch RAO (five patients). Patients received the Royal Brisbane and Women's Hospital RAO protocol for their HBOT. Analysis included best corrected visual acuity pre- and post-treatment, subjective improvements, side effects and patient risk factors were also recorded. Results: Improvement in best corrected visual acuity was LogMAR -0.2 for central RAO on average with 8/17 (47%) experiencing objective improvement, 5/17 (29%) experienced no change and 4/22 (24%) experienced a reduction in best corrected visual acuity. Subjective improvement (colour perception or visual fields) was reported in an additional 4/17 patients, resulting in 12/17 (71%) reporting improvement either in visual acuity or subjectively. There was no improvement in the best corrected visual acuity of any of the five patients suffering from branch RAO. Cardiovascular risk factors present in the cohort included hypertension, hypercholesterolaemia, previous cardiovascular events, cardiac disease and smoking. Limited side effects were experienced by this patient cohort with no recorded irreversible side effects. Conclusions: Hyperbaric oxygen treatment appears a safe, beneficial treatment for central RAO. No benefit was demonstrated in branch RAO although numbers were small. Increased awareness of HBOT for RAO resulting in streamlined referrals and transfers and greater uptake of this intervention may further improve patient outcomes. [ABSTRACT FROM AUTHOR]

Penile glans ischaemia post-circumcision is very rare. A 20-year-old male presented with glans ischaemia following an elective circumcision and was successfully treated with a combination of subcutaneous injection of low molecular weight heparin 0.5 mg·kg-1 twice-daily, oral Tadalafil 5 mg once-daily for three days and 12 hyperbaric oxygen treatments at 243 kPa (2.4 atmospheres absolute) beginning 48 hours after the onset of ischaemia. [ABSTRACT FROM AUTHOR]

A 53-year-old woman with a HeartMate III left ventricular assist device (LVAD) was successfully treated under hyperbaric conditions for haemorrhagic cystitis. The HeartMate III LVAD inserted in this patient had not previously been tested or certified for use under hyperbaric conditions. To our knowledge this is the first report of the HeartMate III LVAD being used to support a patient undergoing hyperbaric treatment. The overview detailed here of the safety and technical aspects of managing this patient for hyperbaric treatment was possible due to the collaboration of a multi-disciplinary team. We believe that our experience has demonstrated a pathway to safe hyperbaric treatment of patients dependent upon a HeartMate III LVAD. [ABSTRACT FROM AUTHOR]

Introduction: Hyperbaric oxygen treatment (HBOT) has fourteen approved indications in the management of acute and chronic diseases in various medical specialties. However, lack of physician knowledge and exposure to hyperbaric medicine may hinder the ability of patients to access this treatment option for approved indications. We aimed to determine the prevalence and nature of HBOT-related learning objectives in Canadian undergraduate medical education programs. Methods: Pre-clerkship and clerkship learning objectives from responding Canadian medical schools’ curricula were reviewed. These were acquired through the school websites or by emailing the faculties. Descriptive statistics were used to summarise the number of hyperbaric medicine objectives taught in Canadian medical schools, and within each institution. Results: Learning objectives from seven of the 17 Canadian medical schools were received and reviewed. From the curriculum of the responding schools, only one objective was found to be related to hyperbaric medicine. Hyperbaric medicine was absent from the other six schools’ objectives. Conclusions: Based on the responding Canadian medical schools, hyperbaric medicine objectives were mostly absent from undergraduate medical curricula. These findings illustrate a possible gap in HBOT education and the need for discussion regarding the design and implementation of HBOT educational initiatives in medical training. [ABSTRACT FROM AUTHOR]

Introduction: The performance of the Shangrila590 hyperbaric ventilator (Beijing Aeonmed Company, Beijing, China) was evaluated during volume-controlled ventilation. Methods: Experiments were conducted in a multiplace hyperbaric chamber at 101, 152, 203, and 284 kPa (1.0, 1.5, 2.0 and 2.8 atmospheres absolute [atm abs]). With the ventilator in volume control ventilation (VCV) mode and connected to a test lung, comparison was made of the set tidal volume (VTset) versus delivered tidal volume (VT) and minute volume (MV) at VTset between 400 and 1,000 mL. Peak inspiratory pressure was also recorded. All measurements were made across 20 respiratory cycles. Results: Across all ambient pressures and ventilator settings the difference between VTset and actual VT and between predicted MV and actual MV were small and clinically insignificant despite reaching statistical significance. Predictably, Ppeak increased at higher ambient pressures. With VTset 1,000 mL at 2.8 atm abs the ventilator produced significantly greater VT, MV and Ppeak. Conclusions: This new ventilator designed for use in hyperbaric environments performs well. It provides relatively stable VT and MV during VCV with VTset from 400 mL to 800 mL at ambient pressures from 1.0 to 2.8 atm abs, as well as VTset 1,000 mL at ambient pressures from 1.0 to 2.0 atm abs. [ABSTRACT FROM AUTHOR]

Introduction: Previous studies have demonstrated the beneficial effects of treadmill exercise (EX) on osteoporosis, and of hyperbaric oxygen (HBO) on osteoblast and osteoclast formation in vitro. We investigated the effects of HBO and the combination of HBO and EX on osteoporosis in ovariectomized rats. Methods: Forty 3-month-old female Sprague-Dawley rats were randomly divided into 5 groups (n = 8): a sham control group (Control); an ovariectomy group; an ovariectomy with treadmill exercise treatment group; an ovariectomy with HBO treatment group; and an ovariectomy with HBO treatment combined with treadmill exercise group. The HBO exposures were 203 kPa, 85–90% O2, 90 min and the exercise regimen was 20 m·min-1, 40 min·day¹, 5o slope. Both treatments were administered once daily, five days a week for 12 weeks until the rats were sacrificed. Results: All three treatments (HBO, exercise, and both combined) significantly promoted the expression of the osteoblast‐ related gene and oxidative metabolism-related gene (PGC-1α). They also exerted significant inhibitory effects on the osteoclast‐related mRNA expression (RANKL) and bone resorption marker CTX‐I. Additionally, exercise and the combination exercise-HBO treatment increased serum superoxide dysmutase (SOD) and sclerostin expression. No significant betweengroup difference was observed. Conclusions: Hyperbaric oxygen, exercise, and the combination ameliorated bone microarchitecture deterioration and ovariectomy-induced bone loss in rats, and these inhibitory effects may be associated with the increased SOD and upregulated PGC-1α. [ABSTRACT FROM AUTHOR]

Introduction: End-tidal carbon dioxide (ETCO2) monitoring is essential for monitoring intubated critical care patients, yet its use in hyperbaric environments can be problematic. We postulated that the EMMA mainstream capnometer may function accurately under hyperbaric conditions. Methods: Stage 1. The EMMA mainstream capnometer was tested at 101 kPa against a reference side-stream capnometer, Philips IntelliVue M3015B microstream, using 10 customised reference gases of various carbon dioxide (CO2) concentrations (2.47%−8.09%, or 18.5−60.7 mmHg at 101 kPa) in either air or oxygen. Stage 2. The functionality and accuracy of the EMMA capnometer was tested under hyperbaric conditions, 121–281 kPa, using the same test gases. Results: At 101 kPa, the EMMA capnometer measured CO2 at levels lower than expected (mean of differences = -2.5 mmHg (95% CI -2.1 to -2.9, P<0.001)). The Philips capnometer measured CO2 more closely to expected CO2 (mean of differences = -1.1 mmHg (95% CI -0.69 to -1.4, P<0.001). Both devices demonstrated a significant linear relationship with expected CO2. The EMMA capnometer functioned up to the maximum test pressure (281 kPa). The device over-read CO2 measurements at pressures > 141 kPa. Although variance increased at pressures in the therapeutic range for hyperbaric treatments, a significant linear relationship between expected and EMMA measured CO2 was demonstrated. The EMMA capnometer tolerated pressures to 281 kPa, but its display was limited to CO2 < 99 mmHg. Conclusions: This study validated EMMA capnometer function to 281 kPa in the hyperbaric environment. The device overread CO2 measurements at pressures >141 kPa, however there was a linear relationship between expected and measured CO2. The EMMA capnometer may be clinically useful for monitoring expired CO2 in patients undergoing hyperbaric oxygen treatment. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to determine the lowest possible atmospheric pressure in the 111−152 kPa (1.1−1.5 atmospheres absolute [atm abs]) range that would require the patients to equalise their ears, allowing an effective sham for a 203 kPa (2.0 atm abs) hyperbaric exposure. Methods: We performed a randomised controlled study on 60 volunteers divided into 3 groups (compression to 111, 132 and 152 kPa (1.1, 1.3, 1.5 atm abs) to determine the minimum pressure to obtain blinding. Secondly, we applied additional blinding strategies (faster compression with ventilation during the fictitious compression time, heating at compression, cooling at decompression) on 25 new volunteers in order to enhance blinding. Results: The number of participants who did not believe they had been compressed to 203 kPa was significantly higher in the 111 kPa compressed arm than in the other two arms (11/18 vs 5/19 and 4/18 respectively; P = 0.049 and P = 0.041, Fisher’s exact test). There was no difference between compressions to 132 and 152 kPa. By applying additional blinding strategies, the number of participants who believed they had been compressed to 203 kPa increased to 86.5 %. Conclusions: A compression to 132 kPa, (1.3 atm abs, 3 metres of seawater equivalent) combined with the additional blinding strategies of forced ventilation, enclosure heating and compression in five minutes, simulates a therapeutic compression table and can be used as a hyperbaric placebo. [ABSTRACT FROM AUTHOR]

Introduction: The Eustachian tube (ET) is essential for fast and direct pressure equalisation between middle ear and ambient pressure. It is not yet known to what extent Eustachian tube function in healthy adults changes in a weekly periodicity due to internal and external factors. This question is particularly interesting with regard to scuba divers among whom there is a need to evaluate intraindividual ET function variability. Methods: Continuous impedance measurement in a pressure chamber was performed three times at one-week intervals between measurements. Twenty healthy participants (40 ears) were enrolled. Using a monoplace hyperbaric chamber, individual subjects were exposed to a standardised pressure profile consisting of a 20 kPa decompression over 1 min, a 40 kPa compression over 2 min, and a 20 kPa decompression over 1 min. Measurements of Eustachian tube opening pressure (ETOP), opening duration (ETOD), and opening frequency (ETOF) were made. Intraindividual variability was assessed. Results: Mean ETOD during compression (actively induced pressure equalisation) on the right side was 273.8 (SD 158.8) ms, 259.4 (157.7) ms, and 249.2 (154.1) ms (Chi-square 7.30, P = 0.026) across weeks 1−3. Mean ETOD for both sides was 265.6 (153.3) ms, 256.1 (154.6) ms, and 245.7 (147.8) ms (Chi-square 10.00, P = 0.007) across weeks 1−3. There were no other significant differences in ETOD, ETOP and ETOF across the three weekly measurements. Conclusions: This longitudinal study suggests low week-to-week intraindividual variability of Eustachian tube function. [ABSTRACT FROM AUTHOR]

Introduction: Critically ill patients require continuation of their care when receiving hyperbaric oxygen treatment. This care may be facilitated via portable electrically powered devices such as intravenous (IV) infusion pumps and syringe drivers, which may create risks in the absence of a comprehensive safety evaluation. We reviewed published safety data for IV infusion pumps and powered syringe drivers in hyperbaric environments and compared the evaluation processes to key requirements documented in safety standards and guidelines. Methods: A systematic literature review was undertaken to identify English language papers published in the last 15 years, describing the safety evaluations of IV pumps and/or syringe drivers for use in hyperbaric environments. Papers were critically assessed in relation to the requirements of international standards and safety recommendations. Results: Eight studies of IV infusion devices were identified. There were deficiencies in the published safety evaluations of IV pumps for hyperbaric use. Despite a simple, published process for evaluating new devices, and available guidelines for fire safety, only two devices had comprehensive safety assessments. Most studies focused only on whether the device functioned normally under pressure and did not consider implosion/explosion risk, fire safety, toxicity, oxygen compatibility or risk of pressure damage. Conclusions: Intravenous infusion (and other electrically powered) devices require comprehensive assessment before use under hyperbaric conditions. This would be enhanced by a publicly accessible database hosting the risk assessments. Facilities should conduct their own assessments specific to their environment and practices. [ABSTRACT FROM AUTHOR]

Introduction: Tamai zone 1 replantation poses a challenge due to the very small size of the vascular structures; often there is no vein for anastomosis. Replantation may have to be done with only an arterial anastomosis. In our study, we aimed to evaluate the success of replantation by combining external bleeding and hyperbaric oxygen treatment (HBOT) in Tamai zone 1 replantation. Methods: Between January 2017 and October 2021, 17 finger replantation patients who underwent artery-only anastomosis due to Tamai zone 1 amputation received 20 sessions of HBOT with external bleeding after the 24th postoperative hour. Finger viability was assessed at the end of treatment. A retrospective review of outcomes was performed. Results: Seventeen clean-cut finger amputation patients were operated on under digital block anaesthesia with a finger tourniquet. No blood transfusion was required. In one patient, complete necrosis developed and stump closure was performed. Partial necrosis was observed in three patients and healed secondarily. Replantation in the remaining patients was successful. Conclusions: Vein anastomosis is not always possible in fingertip replantation. In Tamai zone 1 replantation with artery-only anastomosis, post-operative HBOT with induced external bleeding appeared to shorten the hospital stay and was associated with a high proportion of successful outcomes. [ABSTRACT FROM AUTHOR]

Introduction: Effectiveness of delayed hyperbaric oxygen treatment (HBOT) for decompression illness (DCI) and factors affecting treatment delays have not been studied in large groups of patients. Methods: This retrospective study included 546 DCI patients treated in Finland in the years 1999-2018 and investigated factors associated with recompression delay and outcome. Treatment outcome was defined as fully recovered or presence of residual symptoms on completion of HBOT. The symptoms, use of first aid oxygen, number of recompression treatments needed and characteristics of the study cohort were also addressed. Results: Delayed HBOT (> 48 h) remained effective with final outcomes similar to those treated within 48 h. Cardiopulmonary symptoms were associated with a shorter treatment delay (median 15 h vs 28 h without cardiopulmonary symptoms, P < 0.001), whereas mild sensory symptoms were associated with a longer delay (48 vs 24 h, P < 0.001). A shorter delay was also associated with only one required HBOT treatment (median 24 h vs 34 h for those requiring multiple recompressions) (P = 0.002). Tinnitus and hearing impairment were associated with a higher proportion of incomplete recoveries (78 and 73% respectively, P < 0.001), whereas a smaller proportion of cases with tingling/itching (15%, P = 0.03), nausea (27%, P = 0.03), motor weakness (33%, P = 0.05) and visual disturbances (36%, P = 0.04) exhibited residual symptoms. Patients with severe symptoms had a significantly shorter delay than those with mild symptoms (median 24 h vs 36 h respectively, P < 0.001), and a lower incidence of complete recovery. Conclusions: Delayed HBOT remains an effective and useful intervention. A shorter delay to recompression is associated with fewer recompressions required to achieve recovery or recovery plateau. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to determine the characteristics of decompression illness patients and their treatment outcomes, at the Center of Hyperbaric Medicine, Somdech Phra Pinklao Hospital, one of the largest centres in Thailand. Methods: Past medical records of patients with decompression illness from 2015 to 2021 were retrieved and analysed. Results: Ninety-eight records of diving-related illness from 97 divers were reviewed. Most of the divers were male (n = 50), Thai (n = 86), and were certified at least open water or equivalent (n = 88). On-site first aid oxygen inhalation was provided to 17 divers. Decompression sickness (DCS) cases were characterised according to organ systems involved. The most prominent organ system involved was neurological (57%), followed by mixed organs (28%), musculoskeletal (13%), and pulmonary (2%). There were three cases of arterial gas embolism (AGE). Median presentation delay was three days. Ninety patients were treated with US Navy Treatment Table 6. At the end of their hyperbaric oxygen treatment, most divers (65%) recovered completely. Conclusions: Despite oxygen first aid being given infrequently and long delays before definitive treatment, treatment outcome was satisfactory. Basic knowledge and awareness of diving-related illnesses should be promoted among divers and related personnel in Thailand along with further studies. [ABSTRACT FROM AUTHOR]

Introduction: Previous studies have highlighted hyperoxia-induced microcirculation modifications, but few have focused on hyperbaric oxygen (HBO) effects. Our primary objective was to explore hyperbaric hyperoxia effects on the microcirculation of healthy volunteers and investigate whether these modifications are adaptative or not. Methods: This single centre, open-label study included 15 healthy volunteers. Measurements were performed under five conditions: T0) baseline value (normobaric normoxia); T1) hyperbaric normoxia; T2) hyperbaric hyperoxia; T3) normobaric hyperoxia; T4) return to normobaric normoxia. Microcirculatory data were gathered via laser Doppler, near-infrared spectroscopy and transcutaneous oximetry (PtcO2). Vascular-occlusion tests were performed at each step. We used transthoracic echocardiography and standard monitoring for haemodynamic investigation. Results: Maximal alterations were observed under hyperbaric hyperoxia which led, in comparison with baseline, to arterial hypertension (mean arterial pressure 105 (SD 12) mmHg vs 95 (11), P < 0.001) and bradycardia (55 (7) beats·min-1 vs 66 (8), P < 0.001) while cardiac output remained unchanged. Hyperbaric hyperoxia also led to microcirculatory vasoconstriction (rest flow 63 (74) vs 143 (73) perfusion units, P < 0.05) in response to increased PtcO2 (104.0 (45.9) kPa vs 6.3 (2.4), P < 0.0001); and a decrease in laser Doppler parameters indicating vascular reserve (peak flow 125 (89) vs 233 (79) perfusion units, P < 0.05). Microvascular reactivity was preserved in every condition. Conclusions: Hyperoxia significantly modifies healthy volunteer microcirculation especially during HBO exposure. The rise in PtcO2 promotes an adaptative vasoconstrictive response to protect cellular integrity. Microvascular reactivity remains unaltered and vascular reserve is mobilised in proportion to the extent of the ischaemic stimulus. [ABSTRACT FROM AUTHOR]

Dysbarism is a medical condition arising from change in ambient pressure which outpace the rate at which the body adapts to it. We report a case of recurrent dysbarism consistent with possible decompression illness presenting with amnesia, hypoaesthesia and other neurological manifestations in a professional breath-hold diver treated successfully with hyperbaric oxygen and fluid resuscitation. [ABSTRACT FROM AUTHOR]

Background: Hyperbaric oxygen treatment (HBOT) is often used in an attempt to reverse/treat late radiation-induced tissue fibrosis (LRITF). This study aimed to quantify the effects on skin elasticity. Methods: Skin retraction time was used as a marker of skin elasticity in 13 irradiated breast cancer patients. The measurements were carried out on the affected side as well as the unaffected/healthy side at a mirrored location. Readings were taken at the start and end of HBOT (mean 43 sessions, 80 min at 243 kPa). Results: Patient age ranged from 39–70 years. All patients underwent surgical lumpectomy and radiotherapy prior to undergoing HBOT. The mean time between radiotherapy and HBOT was 70 months. Seven of the 13 patients underwent chemotherapy. Mean irradiated skin retraction time improved from 417 (SD 158) pre-HBOT to 171 (24) msec post-HBOT (P < 0.001). Mean pre-HBOT retraction time in the non-irradiated skin was 143 (20) msec and did not change. Conclusions: This promising pilot study that suggests that HBOT may improve skin elasticity in patients with LRITF. [ABSTRACT FROM AUTHOR]

Respiratory injury during or following hyperbaric oxygen treatment (HBOT) is rare, but associated pressure changes can cause iatrogenic pulmonary barotrauma with potentially severe sequelae such as pneumothoraces. Pulmonary blebs, bullae, and other emphysematous airspace abnormalities increase the risk of respiratory complications and are prevalent in otherwise healthy adults. HBOT providers may elect to use chest X-ray routinely as a pre-treatment screening tool to identify these anomalies, particularly if a history of preceding pulmonary disease is identified, but this approach has a low sensitivity and frequently provides false negative results. Computed tomography scans offer greater sensitivity for airspace lesions, but given the high prevalence of incidental and insignificant pulmonary findings among healthy individuals, would lead to a high false positive rate because most lesions are unlikely to pose a hazard during HBOT. Post-mortem and imaging studies of airspace lesion prevalence show that a significant proportion of patients who undergo HBOT likely have pulmonary abnormalities such as blebs and bullae. Nevertheless, pulmonary barotrauma is rare, and occurs mainly in those with known underlying lung pathology. Consequently, routinely using chest X-ray or computed tomography scans as screening tools prior to HBOT for low-risk patients without a pertinent medical history or lack of clinical symptoms of cardiorespiratory disease is of low value. This review outlines published cases of patients experiencing pulmonary barotrauma while undergoing pressurised treatment/testing in a hyperbaric chamber and analyses the relationship between barotrauma and pulmonary findings on imaging prior to or following exposure. A checklist and clinical decision-making tool based on suggested low-risk and high-risk features are offered to guide the use of targeted baseline thoracic imaging prior to HBOT. [ABSTRACT FROM AUTHOR]

Introduction: Previous studies suggest the effectiveness of hyperbaric oxygen treatment (HBOT) in idiopathic sudden sensorineural hearing loss (ISSNHL) but it is mostly used as an adjuvant and salvage treatment. This study evaluated the effect of primary HBOT according to pretreatment hearing grades and hearing recovery outcomes using modified Siegel’s criteria in patients with ISSNHL. Methods: Fifty-nine ISSNHL patients treated with only HBOT were included. A pure-tone audiogram was recorded before and after a course of HBOT (90 min at 203 kPa daily for 20 days). Using the modified Siegel’s criteria, patients were divided into groups according to hearing threshold before and after treatment. Results: Hearing thresholds were significantly lower after HBOT compared to pre-treatment values across all patients (P < 0.001) with a median value of recovery of 22.5 dB (interquartile range 12.5−33.7 dB). Significantly lower hearing threshold values were recorded at 500, 1,000, 2,000, and 4,000 Hz after treatment (P < 0.001). The greatest recovery was at 1,000 Hz, (change in median threshold = 32 dB) but without a significant difference compared to other frequencies (P = 0.10). Conclusions: HBOT is a legitimate choice as the primary treatment for ISSNHL, especially if it is readily accessible, and if there are contraindications for corticosteroid therapy. [ABSTRACT FROM AUTHOR]