Volatile Organic Compounds in Cellular Headspace after Hyperbaric Oxygen Exposure: An In Vitro Pilot Study.

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.

Chain of events analysis in diving accidents treated by the Royal Netherlands Navy 1966-2023.

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.

An observational study ascertaining the prevalence of bullae and blebs in young, healthy adults and its possible implications for scuba diving.

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.

[Cerebral arterial air embolism: the effect of hyperbaric oxygen therapy]. / Cerebrale arteriële luchtembolie.

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.

DIONYSIUS trial: "Does increasing oxygen nurture your symptomatic ischaemic ulcer sufficiently?" Study protocol for an international multicentre randomised trial.

INTRODUCTION: Diabetic foot ulcers (DFUs) are a major complication of diabetes and often associated with peripheral arterial occlusive disease. Current available evidence shows hyperbaric oxygen therapy (HBOT) can reduce the risk of major amputation, but clinicians remain sceptical about the (cost-)effectiveness and feasibility of HBOT for ischaemic DFUs in clinical practice. Therefore, vascular surgeons and HBOT physicians worldwide feel a strong need for a sufficiently powered clinical trial to determine whether and how many HBOT sessions may be a (cost-)effective adjunctive treatment to ischaemic DFUs. METHODS: An international, multicentre, multi-arm multi-stage design is chosen to conduct an efficient randomised clinical trial. Patients will be randomised to receive standard care (wound treatment and surgical interventions following international guidelines) with either 0, 20, 30 or at least 40 sessions of HBOT. These sessions will comprise 90-120 min of HBOT at a pressure of 2.2-2.5 atmospheres absolute according to international standards. Based on a planned interim analysis, the best performing study arm(s) will continue. Primary end point is major amputation (ie, above ankle) rate after 12 months. Secondary end points are amputation-free survival, wound healing, health-related quality of life and cost-effectiveness. ETHICS AND DISSEMINATION: All patients enrolled in this trial will receive maximum vascular, endovascular or conservative treatment and local wound care according to best practice and (inter)national guidelines. HBOT therapy is added to the standard treatment and is regarded as a low-risk to moderate-risk therapy. The study is approved by the medical ethics committee of the Amsterdam University Medical Centers, location University of Amsterdam. TRIAL REGISTRATION NUMBER: 2020-000449-15, NL9152, NCT05804097.

Hyperbaric Oxygen Therapy for Nonhealing Wounds-A Long-term Retrospective Cohort Study.

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.

Analysis of Volatile Organic Compounds in Exhaled Breath Following a COMEX-30 Treatment Table.

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.

Hyperbaric oxygen treatment for late radiation-induced tissue toxicity in treated gynaecological cancer patients: a systematic review.

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.

Cardiovascular risk assessment in divers: Toward safer diving.

Similar to aviation, diving is performed in an environment in which acute incapacitation may lead to a fatal outcome. In aeromedicine, a pilot is considered "unfit to fly" when the cardiovascular event risk exceeds one percent per annum, the so-called 1% rule. In diving no formal limits to cardiovascular risk have been established. Cardiovascular risk of divers can be calculated using the modified Canadian Cardiovascular Society (CCS) Risk of Harm formula: risk of harm (RH: cardiovascular fatality rate per year during diving: number × 10-5/divers/year) = time diving (TD: number of dives × 10-4) × sudden cardiac incapacitation (SCI: cardiovascular diver event rate per year (number × 10-5/year). The SCI and thus the RH are strongly dependent on age. Using the CCS criterion for RH, 5 × 10-5 divers/year, and considering an average of 25 dives per year per diver, the calculated maximum acceptable SCI is 2%/year, consistent with current practice for dive medical examinations. If the SCI were to exceed 2%/year, a diver could be considered "unfit to dive," which could particularly benefit older (≥ 50 years) divers, in whom cardiovascular risk factors are often not properly treated. For the prevention of fatal diving accidents due to atherosclerotic cardiovascular disease, a dive medical examination is of limited value for young (≺ 50 years) divers who have no cardiovascular risk factors. Introducing a cardiovascular risk management system for divers may achieve a reduction in fatal diving accidents that result from cardiovascular disease in older divers engaged in both recreational and professional diving.

Volatile Organic Compounds Frequently Identified after Hyperbaric Hyperoxic Exposure: The VAPOR Library.

Diving or hyperbaric oxygen therapy with increased partial pressures of oxygen (pO2) 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.

Pulmonary Oxygen Toxicity Through Exhaled Breath Markers After Hyperbaric Oxygen Treatment Table 6.

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.

Hyperbaric oxygen therapy: when pressure is good for diabetic foot ulcers.

The diabetic foot ulcer (DFU) as a common complication of diabetes. Even with adequate treatment, up to 35% of these ulcers do not heal. This is due to the effect of aging, repeated ischemia-reperfusion (IR) injury, bacterial colonisation of the wound and chronic hypoxia. All wound-healing processes are highly dependent on oxygen, so hyperbaric oxygen therapy (HBOT) can be employed to improve wound healing and correct the four pathophysiological factors for chronic wounds. It is, in fact, internationally recognised as a treatment option for non-healing DFUs. Several trials and systematic reviews have been performed on its efficacy, which show a positive trend towards increased wound healing and reduced amputation risk. Some controversy exists due to contradictory results in these studies, which may be due to grouping patients with and without peripheral arterial occlusive disease (PAOD) together. Side effects are usually mild and transient, and the treatment is considered safe.

Hyperbaric oxygen therapy for the treatment of perianal fistulas in 20 patients with Crohn's disease: Results of the HOT-TOPIC trial after 1-year follow-up.

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.

Nutritional status of patients referred for hyperbaric oxygen treatment; a retrospective and descriptive cross-sectional study.

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.

Hyperbaric oxygen treatment for University of Texas grade 3 diabetic foot ulcers: a retrospective cohort study.

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 for Venous Leg Ulcers: A 6 Year Retrospective Study of Results of a Single Center.

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 cm2 [interquartile range (IQR) 32 cm2] to 0.5 cm2 (IQR 5.3 cm2), a median decrease of 7.5 (IQR 16.2 cm2) in cm2 (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.

A survey on the health status of Dutch scuba diving instructors.

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.

Hyperbaric oxygen therapy for the treatment of perianal fistulas in 20 patients with Crohn's disease.

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.