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Background: Military practice or deployment in extreme conditions includes risks, dangers and rare disorders. One of the challenges is frostbite; however, current literature does not provide an overview of this condition in a military context. This review aims to map the incidence, risk factors and outcome of frostbite in military casualties in the armed forces., Methods: A systematic literature search on frostbite (freezing cold injuries) in military settings from 1995 to the present was performed. A critical appraisal of the included articles was conducted. Data on incidence, risk factors, treatment and outcome were extracted., Results: Fourteen studies were included in our systematic review. Most studies of frostbite in a military setting were published nearly half a century ago. Frostbite incidence has declined from 7% to around 1% in armed forces in arctic regions but could be as high as 20% in small-scale arctic manoeuvres. Overall and military-specific risk factors for contracting frostbite were identified., Conclusion: During inevitable arctic manoeuvres, frostbite is a frequently diagnosed injury in service members. Postfreezing symptoms often persist after severe frostbite injury, which decreases employability within the service. Over time, military practice has changed considerably, and modern protective materials have been introduced; therefore, re-evaluation and future study in the military field are appropriate, preferably with other North Atlantic Treaty Organization partners., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2025. No commercial re-use. See rights and permissions. Published by BMJ Group.)

Introduction: The aim was to determine the cost-effectiveness and cost-utility of additional hyperbaric oxygen therapy (HBOT) compared to standard care (SC) for ischaemic diabetic foot ulcers (DFUs) regarding limb salvage and health status., Methods: An economic analysis was conducted, comprising cost-effectiveness and cost-utility analyses, with a 12-month time horizon, using data from the DAMO₂CLES multicentre randomised clinical trial. Cost-effectiveness was defined as cost per limb saved and cost-utility as cost per quality-adjusted life year (QALY). The difference in cost effectiveness between HBOT+SC and SC alone was determined via an incremental cost-effectiveness ratio (ICER)., Results: One-hundred and twenty patients were included, with 60 allocated to HBOT+SC and 60 to SC. No significant cost difference was found in the intention-to-treat analysis: €3,791 (bias corrected and accelerated [BCA] 95% CI, €3,556 - €-11,138). Cost per limb saved showed an ICER of €37,912 (BCA 95% CI €-112,188 - €1,063,561) for HBOT+SC vs. SC. There was no significant difference in mean QALYs: 0.54 for HBOT+SC vs. 0.56 for SC alone (-0.02; BCA 95% CI -0.11-0.08). This resulted in a cost-utility of minus €227,035 (BCA 95% CI €-361,569,550 - €-52,588) per QALY. Subgroup analysis for Wagner stages III/IV showed an ICER of €19,005 (BCA 95%CI, -€18,487 - €264,334) while HBOT did not show any benefit for Wagner stage II., Conclusions: HBOT as an adjunct to SC showed no significant differences in costs and effectiveness for patients with DFUs regarding limb salvage and health status. However, for patients with Wagner stage III/IV ischaemic DFUs there was a trend towards better effectiveness and cost-effectiveness., Competing Interests: No conflicts of interest were declared., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

We present a methodological approach for preclinical research of cerebral arterial gas embolism (CAGE), a condition characterized by gas bubbles within the cerebral circulation causing multifocal ischemia. The current work describes two surgical methods to induce CAGE in the rat: one with injection of air via the external carotid artery (ECA), thereby sacrificing the vessel, and one via direct injection into the common carotid artery (CCA). Male Wistar rats were used and divided into groups (n=5) to undergo either the ECA- or CCA-entry method with injection of different air emboli volumes (6000, 7000 and 8000 nL) or sham surgery. A custom-made bubble generator was used to produce gas emboli with consistent size, and open-source software was developed for real-time bubble analysis. The comparison between the two methods revealed the CCA approach to be superior in terms of consistent bubble production within the bubble generator, reduced embolization time and fewer complications.

This retrospective study analysed a series of investigations on lung function in military divers and the importance of computed tomography (CT) scans concerning fitness to dive. We examined the incidence of blebs and bullae in a population of military divers with large lungs prompted by six cases of pulmonary barotrauma. All of these divers' medicals were normal apart from having large lungs (FVC > 120% predicted). A subsequent survey of the database of all divers and submariners of the Royal Netherlands Navy (RNLN) found another 72 divers/submariners with large lungs who were then evaluated by a CT scan. This resulted in the identification of three further individuals with blebs and/or bullae, who were then declared unfit to dive. In total, the incidence of these lung abnormalities in this cohort was 11.5%. We discuss the possible consequences for fitness to dive with regard to the current literature on the subject, and also consider the most recent standards of reference values for pulmonary function indices. Based on our results and additional insights from other studies, we advise using the Global Lung Initiative reference values for pulmonary function, while performing high resolution CT scans only in divers with clinical indications., Competing Interests: The authors report no conflicts of interest in this work., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Volatile organic compounds (VOCs) might be associated with pulmonary oxygen toxicity (POT). This pilot study aims to identify VOCs linked to oxidative stress employing an in vitro model of alveolar basal epithelial cells exposed to hyperbaric and hyperoxic conditions. In addition, the feasibility of this in vitro model for POT biomarker research was evaluated. The hyperbaric exposure protocol, similar to the U.S. Navy Treatment Table 6, was conducted on human alveolar basal epithelial cells, and the headspace VOCs were analyzed using gas chromatography-mass spectrometry. Three compounds (nonane [ p = 0.005], octanal [ p = 0.009], and decane [ p = 0.018]), of which nonane and decane were also identified in a previous in vivo study with similar hyperbaric exposure, varied significantly between the intervention group which was exposed to 100% oxygen and the control group which was exposed to compressed air. VOC signal intensities were lower in the intervention group, but cellular stress markers (IL8 and LDH) confirmed increased stress and injury in the intervention group. Despite the observed reductions in compound expression, the model holds promise for POT biomarker exploration, emphasizing the need for further investigation into the complex relationship between VOCs and oxidative stress., Competing Interests: The authors declare no conflicts of interest.

Introduction: Diving injuries are influenced by a multitude of factors. Literature analysing the full chain of events in diving accidents influencing the occurrence of diving injuries is limited. A previously published 'chain of events analysis' (CEA) framework consists of five steps that may sequentially lead to a diving fatality. This study applied four of these steps to predominately non-lethal diving injuries and aims to determine the causes of diving injuries sustained by divers treated by the Diving Medical Centre of the Royal Netherlands Navy., Methods: This retrospective cohort study was performed on diving injuries treated by the Diving Medical Centre between 1966 and 2023. Baseline characteristics and information pertinent to all four steps of the reduced CEA model were extracted and recorded in a database., Results: A total of 288 cases met the inclusion criteria. In 111 cases, all four steps of the CEA model could be applied. Predisposing factors were identified in 261 (90%) cases, triggers in 142 (49%), disabling agents in 195 (68%), and 228 (79%) contained a (possible-) disabling condition. The sustained diving injury led to a fatality in seven cases (2%). The most frequent predisposing factor was health conditions (58%). Exertion (19%), primary diver errors (18%), and faulty equipment (17%) were the most frequently identified triggers. The ascent was the most frequent disabling agent (52%)., Conclusions: The CEA framework was found to be a valuable tool in this analysis. Health factors present before diving were identified as the most frequent predisposing factors. Arterial gas emboli were the most lethal injury mechanism., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Introduction: Intrapulmonary air-filled cavities, e.g., bullae, blebs, and cysts, are believed to contribute topulmonary barotrauma (PBT) and arterial gas embolism (AGE) in divers. However, literature is unclear about the prevalence of bullae in healthy adults, ranging from 2.3-33.8%. While this could in part be explained due to increasing quality of radiologic imaging, such as computed tomography (CT) scans, other methodological factors may also affect these findings. This study aims to ascertain the prevalence of bullae in young and healthy adults. Methods: This single-center cross-sectional observational study re-assessed the CT scans of adults (aged 18-40) performed for a clinical suspicion for pulmonary embolism, from 1 January 2016 to 1 March 2020. Presence of bullae was recorded in an electronic database. Chi-square and Fisher exact tests were used for statistical analyses. Additionally, a multivariate logistic regression analysis was performed to study the independent predictive value of identified risk factors. Results: A total of 1,014 cases were identified, of which 836 could be included. Distribution amongst age groups (18-25, 26-30, 31-35, and 36-40) was almost equally, however, 75% of the population was female. Of the male proportion, 41% smoked, compared to 27% in females. In 7.2% (95% CI 5.6-9.1) bullae were identified. The prevalence increased with increasing age ( p < 0.001), with odd ratios up to 5.347 (95% CI 2.164-13.213, p < 0.001) in the oldest age group. Males and smokers had higher odds ratios for bullae of 2.460 (95% CI 1.144-4.208; p = 0.001) and 3.406 (95% CI 1.878-6.157, p < 0.001), respectively. Similar results were seen in the multivariate logistic regression analysis, where age, male sex and smoking were all statistically significant independent risk factors for bullae. Discussion: Bullae were seen in 7.2% of a healthy population up to 40 years old. Increasing age, smoking, and being male were identified as statistically significant risk factors, both in independent and in multivariate logistic regression analyses. Our observations may warrant a re-evaluation of the contribution of bullae to PBT and AGE, as the latter two occur very rarely and bullae appear to be more frequently present than earlier assumed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Bresser, Wingelaar, Van Weering, Bresser and Van Hulst.)

Purpose: Cerebral arterial gas embolism (CAGE) occurs when air or medical gas enters the systemic circulation during invasive procedures and lodges in the cerebral vasculature. Non-contrast computer tomography (CT) may not always show intracerebral gas. CT perfusion (CTP) might be a useful adjunct for diagnosing CAGE in these patients., Methods: This is a retrospective single-center cohort study. We included patients who were diagnosed with iatrogenic CAGE and underwent CTP within 24 h after onset of symptoms between January 2016 and October 2022. All imaging studies were evaluated by two independent radiologists. CTP studies were scored semi-quantitatively for perfusion abnormalities (normal, minimal, moderate, severe) in the following parameters: cerebral blood flow, cerebral blood volume, time-to-drain and time-to-maximum., Results: Among 27 patient admitted with iatrogenic CAGE, 15 patients underwent CTP within the designated timeframe and were included for imaging analysis. CTP showed perfusion deficits in all patients except one. The affected areas on CTP scans were in general located bilaterally and frontoparietally. The typical pattern of CTP abnormalities in these areas was hypoperfusion with an increased time-to-drain and time-to-maximum, and a corresponding minimal decrease in cerebral blood flow. Cerebral blood volume was mostly unaffected., Conclusion: CTP may show specific perfusion defects in patients with a clinical diagnosis of CAGE. This suggests that CTP may be supportive in diagnosing CAGE in cases where no intracerebral gas is seen on non-contrast CT., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Author(s). Published by Elsevier B.V. All rights reserved.)

Pulmonary oxygen toxicity (POT), an adverse reaction to an elevated partial pressure of oxygen in the lungs, can develop as a result of prolonged hyperbaric hyperoxic conditions. Initially starting with tracheal discomfort, it results in pulmonary symptoms and ultimately lung fibrosis. Previous studies identified several volatile organic compounds (VOCs) in exhaled breath indicative of POT after various wet and dry hyperbaric hypoxic exposures, predominantly in laboratory settings. This study examined VOCs after exposures to 81 metres of seawater by three navy divers during operational heliox diving. Univariate testing did not yield significant results. However, targeted multivariate analysis of POT-associated VOCs identified significant (P = 0.004) changes of dodecane, tetradecane, octane, methylcyclohexane, and butyl acetate during the 4 h post-dive sampling period. No airway symptoms or discomfort were reported. This study demonstrates that breath sampling can be performed in the field, and VOCs indicative of oxygen toxicity are exhaled without clinical symptoms of POT, strengthening the belief that POT develops on a subclinical-to-symptomatic spectrum. However, this study was performed during an actual diving operation and therefore various confounders were introduced, which were excluded in previous laboratory studies. Future studies could focus on optimising sampling protocols for field use to ensure uniformity and reproducibility, and on establishing dose-response relationships., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Background: Iatrogenic gas embolism is the presence of gas in vascular structures. Feared are those in coronary or cerebral arteries. These can result in cerebral or myocardial infarction., Case Description: A 79-year-old female underwent CT-guided biopsy of the lung. Minutes later she developed neurological symptoms. After administration of oxygen her symptoms initially improved, but later worsened. Based on her symptoms air embolism was suspected. She recovered fully after treatment with hyperbaric oxygen., Conclusion: Air embolism is a potentially life-threatening complication of surgical, radiological or vascular interventions. Early recognition can lead to prompt treatment and better prognosis. If air embolism is suspected the patient should be treated according to ABCDE principles and oxygen should be administered. In case of neurological or circulatory symptoms a hospital that could provide hyperbaric oxygen therapy should be contacted as soon as possible.

Background: Iatrogenic cerebral arterial gas embolism (CAGE) caused by invasive medical procedures may be treated with hyperbaric oxygen therapy (HBOT). Previous studies suggested that initiation of HBOT within 6-8 h is associated with higher probability of favorable outcome, when compared to time-to-HBOT beyond 8 h. We performed a group level and individual patient level meta-analysis of observational studies, to evaluate the relationship between time-to-HBOT and outcome after iatrogenic CAGE., Methods: We systematically searched for studies reporting on time-to-HBOT and outcome in patients with iatrogenic CAGE. On group level, we meta-analyzed the differences between median time-to-HBOT in patients with favorable versus unfavorable outcome. On individual patient level, we analyzed the relationship between time-to-HBOT and probability of favorable outcome in a generalized linear mixed effects model., Results: Group level meta-analysis (ten studies, 263 patients) shows that patients with favorable outcome were treated with HBOT 2.4 h (95% CI 0.6-9.7) earlier than patients with unfavorable outcome. The generalized linear mixed effects model (eight studies, 126 patients) shows a significant relationship between time-to-HBOT and probability of favorable outcome (p = 0.013) that remains significant after correcting for severity of manifestations (p = 0.041). Probability of favorable outcome decreases from approximately 65% when HBOT is started immediately, to 30% when HBOT is delayed for 15 h., Conclusions: Increased time-to-HBOT is associated with decreased probability of favorable outcome in iatrogenic CAGE. This suggests that early initiation of HBOT in iatrogenic CAGE is of vital importance., (© 2023. The Author(s).)

Objective: To analyze wound healing results of hyperbaric oxygen therapy (HBOT) for a variety of different wound types., Methods: This retrospective cohort study included all patients treated with HBOT and wound care at a single hyperbaric center between January 2017 and December 2020. The primary outcome was wound healing. Secondary outcome measures were quality of life (QoL), number of sessions, adverse effects, and treatment cost. Investigators also examined possible influencing factors, including age, sex, type and duration of wound, socioeconomic status, smoking status, and presence of peripheral vascular disease., Results: A total of 774 treatment series were recorded, with a median of 39 sessions per patient (interquartile range, 23-51 sessions). In total, 472 wounds (61.0%) healed, 177 (22.9%) partially healed, 41 (5.3%) deteriorated, and 39 (5.0%) minor and 45 (5.8%) major amputations were performed. Following HBOT, median wound surface area decreased from 4.4 cm 2 to 0.2 cm 2 ( P < .01), and patient QoL improved from 60 to 75 on a 100-point scale ( P < .01). The median cost of therapy was €9,188 (interquartile range, €5,947-€12,557). Frequently recorded adverse effects were fatigue, hyperoxic myopia, and middle ear barotrauma. Attending fewer than 30 sessions and having severe arterial disease were both associated with a negative outcome., Conclusions: Adding HBOT to standard wound care increases wound healing and QoL in selected wounds. Patients with severe arterial disease should be screened for potential benefits. Most reported adverse effects are mild and transient., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

The COMEX-30 hyperbaric treatment table is used to manage decompression sickness in divers but may result in pulmonary oxygen toxicity (POT). Volatile organic compounds (VOCs) in exhaled breath are early markers of hyperoxic stress that may be linked to POT. The present study assessed whether VOCs following COMEX-30 treatment are early markers of hyperoxic stress and/or POT in ten healthy, nonsmoking volunteers. Because more oxygen is inhaled during COMEX-30 treatment than with other treatment tables, this study hypothesized that VOCs exhaled following COMEX-30 treatment are indicators of POT. Breath samples were collected before and 0.5, 2, and 4 h after COMEX-30 treatment. All subjects were followed-up for signs of POT or other symptoms. Nine compounds were identified, with four (nonanal, decanal, ethyl acetate, and tridecane) increasing 33-500% in intensity from before to after COMEX-30 treatment. Seven subjects reported pulmonary symptoms, five reported out-of-proportion tiredness and transient ear fullness, and four had signs of mild dehydration. All VOCs identified following COMEX-30 treatment have been associated with inflammatory responses or pulmonary diseases, such as asthma or lung cancer. Because most subjects reported transient pulmonary symptoms reflecting early-stage POT, the identified VOCs are likely markers of POT, not just hyperbaric hyperoxic exposure.

Purpose: The aim of this study was to investigate the result of hyperbaric oxygen therapy (HBOT) in women with treated gynaecological malignancies who suffer from late radiation-induced tissue toxicity (LRITT). Moreover, which symptoms of LRITT benefit most from HBOT was evaluated as well., Material and Methods: An online literature search was conducted using PubMed; Embase and the Cochrane Library. Studies were included if the study examined gynaecological cancer patients who had been treated with radiotherapy, who suffered from LRITT and who subsequently received HBOT. In addition, the outcome measures were based on examining the effects of HBOT., Results: Twenty-one articles were included. The study investigating proctitis reported an improvement and three out of four studies investigating cystitis reported decreased complaints in women treated for gynaecological malignancies. In addition, all studies reported improvement in patients with wound complications and fifty percent of the studies reported better Patient Reported Outcome Measurements (PROMS) in women with gynaecological malignancies. Finally, all studies, except one related to pelvic malignancies reported reduced prevalence of symptoms for cystitis and proctitis and all studies reported better PROMS. However, only eleven studies reported p-values, nine of which were significant., Conclusion: This study demonstrated that HBOT has a positive effect in women with gynaecological LRITT. Within the included patient group, gynaecological cancer patients with wound complications seem to benefit most from this treatment compared to other late side effects of LRITT., (© 2022. The Author(s).)

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., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Background: Late side effects of radiotherapy in patients with head and neck cancer (HNCPs) result in decreased tissue vascularity, a compromised healing capacity and spontaneous breakdown of tissue. The aim of this study was to examine the in vivo effect of hyperbaric oxygen therapy (HBOT) on the microcirculation in irradiated oral tissue., Methods: Using a handheld microscope, the effect of HBOT on oral mucosal microcirculation parameters was measured in 34 previously irradiated HNCPs prior to HBOT and at 4 weeks and 6 months posttreatment., Results: A significant increase in mean buccal vessel density and decrease in buccal vessel diameter was found 6 months after HBOT compared to baseline, 22 ± 11 versus 25 ± 7 cpll/mm 2 (p < 0.05) and 20 ± 4 versus 16 ± 5 μm (p < 0.05), respectively., Conclusion: Our results indicate that oral microcirculation histopathology associated with irradiation is able to respond to HBOT by redirecting oral microcirculation parameters towards values consistent with healthy tissue., (© 2022 The Authors. Head & Neck published by Wiley Periodicals LLC.)

Diving or hyperbaric oxygen therapy with increased partial pressures of oxygen (pO 2 ) can have adverse effects such as central nervous system oxygen toxicity or pulmonary oxygen toxicity (POT). Prevention of POT has been a topic of interest for several decades. One of the most promising techniques to determine early signs of POT is the analysis of volatile organic compounds (VOCs) in exhaled breath. We reanalyzed the data of five studies to compose a library of potential exhaled markers for the early detection of POT. GC-MS data from five hyperbaric hyperoxic studies were collected. Wilcoxon signed-rank tests were used to compare baseline- and postexposure measurements; all ion fragments that significantly varied were compared by similarity using the National Institute of Standards and Technology (NIST) library. All identified molecules were cross-referenced with open-source databases and other scientific publications on VOCs to exclude compounds that occurred as a result of contamination, and to identify the compounds most likely to occur due to hyperbaric hyperoxic exposure. After identification and removal of contaminants, 29 compounds were included in the library. This library of hyperbaric hyperoxic-related VOCs can help to advance the development of an early noninvasive marker of POT. It enables validation by others who use more targeted MS-related techniques, instead of full-scale GC-MS, for their exhaled VOC research.

Introduction: The hyperbaric oxygen treatment table 6 (TT6) is widely used to manage dysbaric illnesses in divers and iatrogenic gas emboli in patients after surgery and other interventional procedures. These treatment tables can have adverse effects, such as pulmonary oxygen toxicity (POT). It is caused by reactive oxygen species' damaging effect in lung tissue and is often experienced after multiple days of therapy. The subclinical pulmonary effects have not been determined. The primary aim of this study was to measure volatile organic compounds (VOCs) in breath, indicative of subclinical POT after a TT6. Since the exposure would be limited, the secondary aim of this study was to determine whether these VOCs decreased to baseline levels within a few hours. Methods: Fourteen healthy, non-smoking volunteers from the Royal Netherlands Navy underwent a TT6 at the Amsterdam University Medical Center-location AMC. Breath samples for GC-MS analysis were collected before the TT6 and 30 min, 2 and 4 h after finishing. The concentrations of ions before and after exposure were compared by Wilcoxon signed-rank tests. The VOCs were identified by comparing the chromatograms with the NIST library. Compound intensities over time were tested using Friedman tests, with Wilcoxon signed-rank tests and Bonferroni corrections used for post hoc analyses. Results: Univariate analyses identified 11 compounds. Five compounds, isoprene, decane, nonane, nonanal and dodecane, showed significant changes after the Friedman test. Isoprene demonstrated a significant increase at 30 min after exposure and a subsequent decrease at 2 h. Other compounds remained constant, but declined significantly 4 h after exposure. Discussion and Conclusion: The identified VOCs consisted mainly of (methyl) alkanes, which may be generated by peroxidation of cell membranes. Other compounds may be linked to inflammatory processes, oxidative stress responses or cellular metabolism. The hypothesis, that exhaled VOCs would increase after hyperbaric exposure as an indicator of subclinical POT, was not fulfilled, except for isoprene. Hence, no evident signs of POT or subclinical pulmonary damage were detected after a TT6. Further studies on individuals recently exposed to pulmonary irritants, such as divers and individuals exposed to other hyperbaric treatment regimens, are needed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 de Jong, Wingelaar, Brinkman, van Ooij, Maitland-van der Zee, Hollmann and van Hulst.)

Background: Previously published short-term results (week 16) of this trial showed a significant improvement in clinical, radiologic and biochemical outcomes in Crohn's disease patients with therapy-refractory perianal fistulas after treatment with hyperbaric oxygen therapy., Objective: To assess the long-term (week 60) efficacy, safety and feasibility of hyperbaric oxygen therapy in perianal fistula in Crohn's disease., Methods: Crohn's disease patients with high perianal fistula(s) failing conventional treatment >6 months were included. Exclusion criteria were presence of a stoma, rectovaginal fistula(s) and recent changes in treatment regimens. Patients received 40 hyperbaric oxygen sessions and outcomes were assessed at week 16 and week 60., Results: Twenty patients were included (median age 34 years). At week 16, median scores of the perianal disease activity index and modified Van Assche index (co-primary outcomes) decreased from 7.5 (95% CI 6-9) to 4 (95% CI 3-6, p < 0.001) and 9.2 (95% CI 7.3-11.2) to 7.3 (95% CI 6.9-9.7, p = 0.004), respectively. At week 60, the respective scores remained significantly lower than baseline: 4 (95% CI 3-7, p < 0.001) and 7.7 (95% CI 5.2-10.2, p = 0.003). Perianal disease activity index score of 4 or less (representing inactive perianal disease) was observed in 13 patients at week 16 and 12 patients at week 60. Using fistula drainage assessment, 12 and 13 patients showed a clinical response at week 16 and 60, respectively, and clinical remission was achieved in four patients for both time points. At week 16, a statistically significant biochemical improvement (C-reactive protein and faecal calprotectin levels) was found, but this effect was no longer significant at week 60., Conclusions: The clinical and radiologic improvement of perianal fistula in Crohn's disease, that was found at week 16 after treatment with hyperbaric oxygen therapy, is maintained at 1-year follow-up., (© 2021 The Authors. United European Gastroenterology Journal published by Wiley Periodicals LLC on behalf of United European Gastroenterology.)

Hyperbaric oxygen therapy (HBOT) consists of breathing 100% oxygen under increased ambient pressure. There are indications that HBOT induces oxidative stress and activates immune pathways. However, previous research on immunological effects of HBOT has mainly been established in in vitro experiments and selected patient populations, limiting generalizability and increasing the chances of confounding by comorbidities and specific patient-related factors. More insight into the immunological effects of HBOT would aid investigation and comprehension of potentially novel treatment applications. Therefore, in this study, we investigated the effects of three 110-min HBOT-sessions with 24-h intervals on immunological parameters in healthy, young, male volunteers. Blood samples were obtained before and after the first and third HBOT sessions. We assessed neutrophilic reactive oxygen species (ROS) production, systemic oxidative stress [plasma malondialdehyde (MDA) concentrations] as well as neutrophil phagocytic activity, plasma concentrations of tumor necrosis factor (TNF), interleukin (IL)-6, IL-8, and IL-10, and production of TNF, IL-6, and IL-10 by leukocytes ex vivo stimulated with the Toll-like receptor (TLR) ligands lipopolysaccharide (TLR4) and Pam3Cys (TLR2). We observed decreased neutrophilic ROS production and phagocytosis following the second HBOT session, which persisted after the third session, but no alterations in MDA concentrations. Furthermore, plasma concentrations of the investigated cytokines were unaltered at all-time points, and ex vivo cytokine production was largely unaltered over time as well. These results indicate no induction of systemic oxidative stress or a systemic inflammatory response after repeated HBOT in healthy volunteers but may suggest exhaustion of ROS generation capacity and phagocytosis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 de Wolde, Hulskes, de Jonge, Hollmann, van Hulst, Weenink and Kox.)

Introduction: Due to the global rise of obesity, the role of nutrition has gathered more attention. Paradoxically, even overweight persons may be malnourished. This may delay wound healing or recovery of late radiation tissue injury (LRTI). Hyperbaric oxygen treatment (HBOT) is used to improve wound healing or LRTI complaints. The aim of this study was to assess the dietary intake levels of nutrients important for recovery in patients referred for HBOT., Methods: This was a retrospective, cross-sectional study of patients referred for HBOT to a single centre between 2014 and 2019. Patients were offered a consultation with a dietitian as standard care. Information on nutrients was calculated from questionnaires, and compared to recommended daily allowances., Results: One hundred and forty-six patients were included (80 female). Eighteen patients were treated for diabetic ulcers, 25 for non-diabetic ulcers and 103 for LRTI. Most were overweight or obese (64.4%), but did not consume the recommended quantities of calories, protein, or micronutrients. Vitamin C consumption was higher than recommended. Male patients had a higher intake of calories and protein than female patients but not other nutrients. No differences in intake existed between age or body mass index categories., Conclusions: The nutritional status of patients referred for HBOT may be inadequate for healing wounds or LRTI, despite anthropomorphic data indicating a positive energy balance. Daily attendance for HBOT provides a unique opportunity to monitor and correct these deficiencies. Routine screening for malnutrition and supplement deficiencies is recommended for patients referred for HBOT., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Background: Acute acoustic trauma (AAT) is an acute hearing impairment caused by intense noise-impact. The current management strategy for AAT with substantial hearing loss in the Dutch military is the combination therapy with corticosteroids and hyperbaric oxygen therapy (HBOT). In a previous study, early initiation of the combination therapy was associated with better outcomes. Therefore, we performed a new analysis to assess the difference in hearing outcome between patients in whom combination therapy was started within two days, versus after more than two days., Methods: A retrospective analysis was performed on military patients diagnosed with AAT with substantial hearing loss who presented between February 2018 and March 2020. Absolute and relative hearing improvement between first and last audiograms were calculated for all affected frequencies (defined as loss of ≥20 dB on initial audiogram). We also determined the amount of patients who recovered to the level of Dutch military requirement, and performed speech discrimination tests., Results: In this analysis, 30 male patients (49 ears) with AAT were included. The median age was 24.5 years (IQR 23-29). The median time to initiation of therapy with corticosteroids and HBOT were one and two days, respectively. HBOT was started within two days in 31 ears, and after more than two days in 18 ears. The mean absolute and relative hearing gains were 18.8 dB (SD 14.6) and 46.8% (SD 31.3) on all affected frequencies. The 100% discrimination/speech perception level improved from 64.0 dB to 51.7 dB (gain 12.3 dB ± 14.1). There was significantly more improvement in absolute and relative hearing improvement when HBOT was started in ≤2 days, compared to >2 days., Conclusion: Our analysis shows results in favor of early initiation (≤2 days) of the combination treatment of HBOT and corticosteroids in patients with AAT., (© 2021 PLA General Hospital Department of Otolaryngology Head and Neck Surgery. Production and hosting by Elsevier (Singapore) Pte Ltd.)

Aim: Hard-to-heal diabetic foot ulcers (DFUs) may increase the risk of amputation. This study reports the positive influence of hyperbaric oxygen therapy (HBOT) on hard-to-heal DFUs involving underlying bone., Method: A single-centre, retrospective cohort study reporting the results of HBOT and wound care on hard-to-heal University of Texas grade 3 DFUs (i.e., involving underlying bone) between 2013 and 2019. Outcome measures were primarily (near-) complete wound healing (i.e., ≥80% ulcer surface area reduction) and amputation rate (minor or major), and secondarily the number of hyperbaric sessions and improvement in quality of life (QoL) and pain score., Results: The study included 206 patients, of whom 74 (36%) achieved complete wound healing, and 75 (36%) near-complete healing. Amputations were performed in 27 patients (13%): 12 (6%) minor and 15 (7%) major. The median number of HBOT sessions was 42. Participants who achieved complete healing received a median of 43 sessions, compared with 10 for those who required major amputation. Patients with at least 30 sessions were less likely to undergo amputation (odds ratio: 0.08; 95% confidence interval (CI): 0.03-0.21). Mean QoL increased by 7.6 points (95%CI: 3.9-11.3; p<0.01) and median pain score fell from 3 to 1 (0-3) (p<0.01)., Conclusions: The addition of HBOT to standard wound care may lead to a decreased amputation risk, improved wound healing and increased QoL for people with a University of Texas grade 3 DFU. An adequate number of HBOT sessions is required to achieve optimal clinical results. Objective selection criteria and shared decision-making are suggested to improve dropout rates.

Hyperbaric oxygen therapy (HBOT) is commonly used as treatment in several diseases, such as non-healing chronic wounds, late radiation injuries and carbon monoxide poisoning. Ongoing research into HBOT has shown that preconditioning for surgery is a potential new treatment application, which may reduce complication rates and hospital stay. In this review, the effect of HBOT on oxidative stress, inflammation and angiogenesis is investigated to better understand the potential mechanisms underlying preconditioning for surgery using HBOT. A systematic search was conducted to retrieve studies measuring markers of oxidative stress, inflammation, or angiogenesis in humans. Analysis of the included studies showed that HBOT-induced oxidative stress reduces the concentrations of pro-inflammatory acute phase proteins, interleukins and cytokines and increases growth factors and other pro-angiogenesis cytokines. Several articles only noted this surge after the first HBOT session or for a short duration after each session. The anti-inflammatory status following HBOT may be mediated by hyperoxia interfering with NF-κB and IκBα. Further research into the effect of HBOT on inflammation and angiogenesis is needed to determine the implications of these findings for clinical practice.

Objectives: Iatrogenic cerebral arterial gas embolism occurs when gas enters the cerebral arterial circulation during a medical procedure and is considered a severe complication. Seizures have been described in these patients, but information on clinical characteristics, treatment, and outcome is lacking in current literature. The aim of the study was to explore seizures in patients with iatrogenic cerebral arterial gas embolism and to evaluate management strategies., Design: Retrospective single-center observational study., Setting: The only university hospital in the Netherlands with a hyperbaric oxygen therapy facility., Patients: All patients presenting at or referred to our center with iatrogenic cerebral arterial gas embolism between May 2016 and December 2020., Interventions: Not applicable., Measurements and Main Results: Fifteen patients with iatrogenic cerebral arterial gas embolism were identified, of whom 11 (73%) developed seizures. Five patients developed their first seizure prior to hyperbaric oxygen therapy, three during hyperbaric oxygen therapy, and three after hyperbaric oxygen therapy. Of the 11 patients with seizures, all but one were treated with anti-epileptic drugs. With a median follow-up time of 5 months (range, 1-54 mo), five patients showed complete neurologic recovery, five had minor neurologic deficit, two had moderate to severe neurologic deficit, and three had died. Four patients still used anti-epileptic drugs at follow-up. No patients had recurrent seizures after hospital discharge., Conclusions: `Seizures are a common symptom in iatrogenic cerebral arterial gas embolism. They are often treated with anti-epileptic drugs and do not seem to lead to chronic epilepsy., Competing Interests: The authors have disclosed that they do not have any potential conflicts of interest., (Copyright © 2021 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.)

Background: Venous leg ulcers (VLUs) are common and have a large impact on healthcare budgets worldwide. Hyperbaric oxygen therapy (HBOT) may improve healing of these ulcers. Methods: Retrospective, single-center cohort study between 2013 and 2019. All patients with a VLU from an outpatient clinic providing HBOT and wound care were included. The primary outcome measure was wound healing, determined at discharge from the center. Other outcome measures were improvement in patient related outcome measures (PROMs), as assessed by the EQ-5D-3L questionnaire and including quality of life (QoL) and pain score. Results: Fifty patients were included, 53% female, with a mean age of 73.4 (±12.2). Most wounds (83%) had existed longer than 3 months before starting treatment. Patients received an average of 43 (±20) sessions of HBOT. After treatment, 37 patients (63%) achieved complete or near-complete wound healing. Wound size decreased from a median of 14 cm 2 [interquartile range (IQR) 32 cm 2 ] to 0.5 cm 2 (IQR 5.3 cm 2 ), a median decrease of 7.5 (IQR 16.2 cm 2 ) in cm 2 (94%). Patients mostly reported improvement for all health aspects on the questionnaire. Pain score decreased from 5.7 (±2.5) to 2.1 (±2.2) ( p < 0.0001) and health score increased from 57.2 (±15.6) to 69.9 (±18.9) ( p = 0.02). Conclusions: Patients with non-healing VLUs may benefit from HBOT to achieve complete or substantial wound healing. We recommend a well-designed randomized clinical trial with a number of patients allowing enough statistical power, and of a reasonable duration, to establish the potential of additional HBOT on hard-to-heal venous ulcers., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Lalieu, Akkerman and van Hulst.)

Background: Positive effects of hyperbaric oxygen (HBO) on perianal fistulas in Crohn's disease (CD) have been described, but the effect on rectovaginal fistulas (RVFs) has not yet been studied. The aim was to investigate the efficacy, safety and feasibility of HBO in patients with RVF in CD., Methods: In this prospective study, consecutive CD patients between November 2018 and February 2020 presenting with RVF at the outpatient fistula clinic of the Amsterdam University Medical Centre were included and selected to receive treatment with 30 daily HBO sessions, if fistulas were actively draining and any concomitant treatment regimen was stable at least 6 weeks prior to start of HBO. Patients with a stoma were excluded. The primary endpoint was clinical closure at 3-month follow-up, defined as cessation of complaints and/or closure of the external orifice if visible at baseline. Secondary outcomes were improvement of concomitant perianal fistulas as measured by the perianal disease activity index (PDAI) and fistula drainage assessment (FDA), as well as improvement in patient-reported outcomes (visual analogue scale (VAS), inflammatory bowel disease questionnaire (IBDQ), faecal incontinence quality of life scale (FIQL) and female sexual functioning index (FSFI)) at 3-month follow-up., Results: Out of 14 eligible patients, nine patients (median age 50 years) were treated, all of whom had previously had one or more unsuccessful medical and/or surgical treatments for their RVF. Clinical closure occurred in none of the patients at 3-month follow-up. There was no improvement in PDAI and patient-reported outcomes (VAS, IBDQ, FIQL and FSFI). Two patients had concomitant perianal fistulas; using FDA, one patient had a clinical response and one patient was in clinical remission 3 months after HBO. There were two treatment-related adverse events during HBO concerning claustrophobia and fatigue. Furthermore, two patients had a surgical intervention due to RVF and two patients were treated with antibiotics for a urinary tract infection during follow-up. One patient had a dose reduction of ustekinumab because of decreased luminal complaints., Conclusion: Treatment with HBO was feasible, but in this therapy-refractory cohort without deviating ostomy no clinical closure of RVF or improvement in quality of life was seen 3 months after HBO. Treatment with HBO alone in this specific group of patients therefore appears to be ineffective., (© The Author(s) 2021. Published by Oxford University Press on behalf of BJS Society Ltd.)

Introduction: As the diving population is ageing, so are the diving instructors. Health issues and the use of prescribed medications are more common when ageing. The death of two diving instructors during one weekend in 2017 in the Netherlands, most likely due to cardiovascular disease, motivated investigation of the prevalence of relevant comorbidities in Dutch diving instructors., Methods: All Dutch Underwater Federation diving instructors were invited to complete an online questionnaire. Questions addressed diving experience and current and past medical history including the use of medications., Results: A response rate of 27% yielded 497 questionnaires (87% male, average age 57.3 years [SD 8.5]). Older instructors were over-represented among responders (82% of males and 75% of females > 50 years versus 66% of males and 51% of females among the invited cohort). Forty-six percent of respondents reported no current medical condition. Hypertension was the most commonly reported condition followed by hay fever and problems equalising ears and sinuses. Thirty-two percent reported no past medical condition. Problems of equalising ears and sinuses was the most common past medical condition, followed by hypertension, joint problems or surgery, and hay fever. Fifty-nine percent used non-prescription medication; predominantly analgesics and nose or ear drops. Forty-nine percent used prescription medicine, mostly cardiovascular and respiratory drugs. Body mass index (BMI) was > 25 kg·m -2 in 66% of males and 38% of females. All instructors with any type of cardiovascular disease were overweight., Conclusions: Nineteen percent of responding diving instructors suffered from cardiovascular disease with above-normal BMI and almost 60% used prescribed or non-prescribed medication. Some dived while suffering from medical issues or taking medications, which could lead to medical problems during emergency situations with their students., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Background: Positive effects of hyperbaric oxygen on perianal fistulas in Crohn's disease have been reported., Aim: To assess efficacy, safety and feasibility of hyperbaric oxygen in Crohn's disease patients with therapy-refractory perianal fistulas., Methods: Twenty consecutive patients were recruited at the out-patient fistula clinic of the Amsterdam UMC. Crohn's disease patients with high perianal fistula(s) failing conventional treatment for over 6 months were included. Exclusion criteria were presence of a stoma, rectovaginal fistula(s) and recent changes in treatment regimens. Patients received treatment with 40 hyperbaric oxygen sessions and outcome parameters were assessed at Week 16., Results: Seven women and 13 men were included (median age 34 years). At Week 16, median scores of perianal disease activity index and modified van Assche index (co-primary outcome parameters) decreased from 7.5 (95% CI 6-9) to 4 (95% CI 3-6, P < 0.001), and from 9.2 (95% CI 7.3-11.2) to 7.3 (95% CI 6.9-9.7, P = 0.004) respectively. Perianal disease activity index scores ≤4 (representing inactive perianal disease) were observed in 13/20 patients (65%). Twelve patients showed a clinical response (60%) and four (20%) clinical remission, assessed with fistula drainage assessment. Median C-reactive protein and faecal calprotectin levels decreased from 4.2 mg/mL (95% CI 1.6-8) to 2.2 (95% CI 0.9-4.3, P = 0.003) and from 399 µg/g (95% CI 52-922) to 31 (95% CI 16-245, P = 0.001), respectively., Conclusions: We found significant clinical, radiological and biochemical improvement in Crohn's disease patients with therapy-refractory perianal fistulas after treatment with hyperbaric oxygen., Clinical Trial Registration: www.trialregister.nl/trial/6489., (© 2020 The Authors. Alimentary Pharmacology & Therapeutics published by John Wiley & Sons Ltd.)

The present article evaluates the results of the treatment with adjuvant hyperbaric oxygen therapy (HBOT) of patients with nonhealing, chronic wounds. In the period 2013 to 2016, 248 patients were referred from various hospitals because of chronic wounds that were recalcitrant in healing despite standard wound care as described in national and international guidelines. After inclusion, all patients were treated with HBOT and subjected to a weekly standard wound care treatment. During each HBOT session, 100% O 2 was administered for 75 minutes under increased pressure of 2.4 ATA. Wounds and quality of life were assessed before and after the total treatment period. A total of 248 patients have been evaluated. Diabetic foot ulcers were present in 134 patients, the remainder (114 patients) showed a variety of wound locations and etiologies. The number of HBOT treatments amounted to an average of 48 (range 20-68) sessions. Before referral to our clinic, 31% of all wounds had existed for at least 18 months (72 patients). After HBOT, 81% of all wounds were near complete healing or completely healed, in 13% of the cases the wound was stable, and in 2% minor or major amputation had to be carried out. The mean treatment time for wounds pre-existing fewer than 6 weeks ("early referrals") was 67 days, and 119 days for wounds pre-existing more than 18 months ("late referrals"). A majority of the patients in our study referred with nonhealing wounds clinically improved when adjuvant HBOT was added to standard wound care protocols. No differences in success rate were seen between diabetic and nondiabetic wounds. It showed that HBOT is a well-tolerated treatment., (© 2020 The Authors. Wound Repair and Regeneration published by Wiley Periodicals LLC on behalf of The Wound Healing Society.)

Introduction: Intrapulmonary pathology, such as bullae or blebs, can cause pulmonary barotrauma when diving. Many diving courses require chest X-rays (CXR) or high-resolution computed tomography (HRCT) to exclude asymptomatic healthy individuals with these lesions. The ability of routine CXRs and HRCT to assess fitness to dive has never been evaluated. Methods: Military divers who underwent yearly medical assessments at the Royal Netherlands Navy Diving Medical Center, including CXR at initial assessment, and who received a HRCT between January and June 2018, were included. The correlations of CXR and HRCT results with fitness to dive assessments were analyzed using Fisher's exact tests. Results: This study included 101 military divers. CXR identified bullae or blebs in seven divers, but HRCT found that these anomalies were not present in three subjects and were something else in four. CXR showed no anomalies in 94 subjects, but HRCT identified coincidental findings in 23 and bullae or blebs in seven. The differences between CXR and HRCT results were statistically significant ( p = 0.023). Of the 34 subjects with anomalies on HRCT, 18 (53%) were disqualified for diving. Discussion: Routine CXR in asymptomatic military divers does not contribute to the identification of relevant pathology in fitness to dive assessments and has a high false negative rate (32%). HRCT is more diagnostic than CXR but yields unclear results, leading to disqualification for diving. Fitness to dive tests should exclude routine CXR; rather, HRCT should be performed only in subjects with clinical indications., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Wingelaar, Bakker, Nap, van Ooij, Endert and van Hulst.)

Scuba diving is an increasingly popular recreational activity in children and adolescents. During the dive medical examination aspects of human physiology, anatomy, and psychology, that differ between adults and children, deserve our special attention. For example, lack of mental maturity, diminished Eustachian tube function and heat loss can pose problems during diving. It is important that children who wish to take up scuba diving are seen by a dive physician, with extra attention to Eustachian tube function. In children, asthma, bronchial hyperreactivity, pulmonary hypertension, and right-to-left shunts are contra-indications for scuba diving. Attention deficit hyperactivity disorder is a relative contra-indication. This article provides a review of the current literature and presents recommendations for recreational diving in children and adolescents. These recommendations are based solely on 'expert' opinion and were accepted by the Dutch Society of Diving and Hyperbaric Medicine in 2020., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)

Background: Surgical procedures that use insufflation carry a risk of gas embolism, which is considered relatively harmless because of the high solubility of carbon dioxide. However, an in vitro study suggested that valveless insufflation devices may entrain non-medical room air into the surgical cavity. Our aim was to verify if this occurs in actual surgical procedures., Methods: The oxygen percentage in the pneumoperitoneum or pneumorectum/pneumopelvis of eight patients operated with use of the AirSeal® was continuously measured, to determine the percentage of air in the total volume of the surgical cavity., Results: Basal air percentage in the surgical cavity was 0-5%. During suctioning from the operative field air percentage increased to 45-65%., Conclusions: The AirSeal® valveless insufflation device maintains optimal distension of the surgical cavity not only by insufflating carbon dioxide, but also by entraining room air, especially during suctioning from the operative field. This may theoretically lead to air embolism in patients operated on with this device.

Massive vascular gas embolism is a feared and often lethal symptom of decompression illness, resulting from diving accidents. The aim of this case report was to correlate post-mortem computed tomography scan (PMCT) findings with autopsy in cases of massive vascular gas embolism. Two cases of fatal diving accidents were retrospectively selected from a forensic radiological pathological database. The PMCT results were initially shared with the forensic pathologist prior to autopsy, enabling a more accurate overall assessment. Both cases were in retrospect thoroughly studied to compare the PMCT findings with the autopsy results. In general, intra- and extra-vascular gas collections are easily detected on PMCT in all body regions. We focused on abundant intravascular gas collections, mainly in the large brain vessels. General autopsy findings are described in both cases, and in one case we elaborate on specific intracerebral changes found at autopsy. Both cases were diagnosed as pulmonary barotrauma with subsequent vascular gas embolisms. We conclude that PMCT excels in the detection of macroscopic gas collections in the body, whereas microscopic gas collections identified at autopsy aid in the differentiation between decompression sickness and pulmonary barotrauma followed by vascular gas embolism. The presented cases highlight the advantages of using both PMCT and autopsy in the post-mortem evaluation of fatal diving accidents.

Background: Metastatic Crohn's disease (CD) is a rare manifestation of CD. It involves inflammatory skin lesions with histopathological findings (granulomas) similar to CD, without connection to the gastrointestinal tract. Hyperbaric oxygen therapy (HBO) has been suggested as a possible treatment option., Objective: This study aimed to identify and treat a consecutive series of patients with biopsy-proven metastatic CD and monitor wound healing using prospectively acquired outcomes., Methods: Pathology results of all patients with ongoing perineal wound-healing problems after proctectomy between 2005 and 2018 at the Amsterdam University Medical Centre were assessed for metastatic CD. Patients with a biopsy-proven diagnosis of perineal metastatic CD were offered HBO (40 daily sessions of 100% oxygen at 2.4 atmosphere absolute). Wound healing was monitored using photographs and standardised questionnaires (the Inflammatory Bowel Disease Questionnaire, EuroQol Visual Analogue Scale and the Female Sexual Function Index) at baseline and 1 and 3 months after HBO., Results: Out of 13 patients in the cohort with persisting perineal wounds after proctectomy, six (46%) had biopsy results consistent with metastatic CD. Of these, three accepted treatment with HBO. All three patients were female. One patient had complete healing of her perineal wound; another patient showed initial improvement but had a flare of luminal and perineal disease at the 3-month follow-up. The third patient showed improvement solely in the questionnaires, with higher scores on all three questionnaires., Conclusion: A high rate of metastatic CD was found in patients with ongoing wound-healing problems after proctectomy, implying that the disease might not be as rare in these selected patients as previously thought. HBO might be beneficial in the treatment of metastatic CD.

Acute cerebral oxygen toxicity (ACOT) is a known side effect of hyperbaric oxygen treatment (HBOT), which can cause generalised seizures. Fortunately, it has a low incidence and is rarely harmful. Nevertheless, we present a case of a 37 year-old patient with morbid obesity who died unexpectedly after an oxygen toxicity seizure in the hyperbaric chamber. Considering possible causes, physiologic changes in obesity and obesity hypoventilation syndrome may increase the risk of ACOT. Obesity, especially in extreme cases, may hinder emergency procedures, both in- and outside of a hyperbaric chamber. Physicians in the hyperbaric field should be aware of the possibility of a fatal outcome after ACOT through the described mechanisms and take appropriate preventative measures. Basic airway management skills are strongly advised for involved physicians, especially when specialised personnel and equipment are not immediately available., (Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.)