Full article is available here - this is an immediate release article.

Effect of a prior hypercapnia experience on recognition of hypercapnia in divers: a randomised controlled study

Thalia Babbage¹, Hanna van Waart¹, Charlotte JW Connell², Nicholas Gant², Simon J Mitchell^1,3,4, Xavier CE Vrijdag¹

¹ Department of Anaesthesiology, University of Auckland, Auckland, New Zealand
² Department of Exercise Sciences, University of Auckland, Auckland, New Zealand
³ Department of Anaesthesia, Auckland City Hospital, Auckland, New Zealand
⁴ Slark Hyperbaric Unit, North Shore Hospital, Auckland, New Zealand

Corresponding author: Dr Xavier Vrijdag, Department of Anaesthesiology, School of Medicine, University of Auckland, Private bag 92019, Auckland 1142, New Zealand
ORCiD: 0000-0001-5907-6083
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Diving medicine; Diving research; Carbon dioxide; Rebreathers – closed circuit; Rebreathing; Technical diving

Abstract
(Babbage T, van Waart H, Connell CJW, Gant N, Mitchell SJ, Vrijdag XCE. Effect of a prior hypercapnia experience on recognition of hypercapnia in divers: a randomised controlled study. Diving and Hyperbaric Medicine. 2026 30 June;56(2):115−124. doi: 10.28920/dhm56.2.115-124. PMID: 42290571.)
Introduction: Rebreather diving carries an increased risk of hypercapnia. Hypercapnia can cause impaired cognition, breathlessness, and increase the risk of oxygen toxicity. We investigated whether a prior unblinded hypercapnia experience, compared to reading about hypercapnia symptoms, would improve divers’ ability to recognise hypercapnia and initiate self-rescue.
Methods: Forty divers were recruited and randomised to receive either an unblinded hypercapnia experience (partial pressure of end-tidal carbon dioxide [PETCO2] of 8.5 kPa) or an information leaflet explaining hypercapnia symptoms. At least one month later, participants in each group were further randomised to undergo blinded exposure to hypercapnia or normocapnia, allocated at 3:1. The primary outcome was the proportion of participants who self-initiated bailout prior to reaching PETCO₂ 8.5 kPa. Continuous cardiorespiratory data (PETCO₂ and PETO₂, tidal volume, respiratory rate, minute ventilation, heart rate, and blood pressure) were also recorded. Subjective symptoms associated with hypercapnia were assessed with a visual analogue scale.
Results: Thirteen of 15 participants (87%) who received the unblinded hypercapnia-experience self-initiated bailout compared to 10/15 information leaflet participants (67%) (P = 0.149). There was no difference in cardiorespiratory physiology parameters at bailout between the groups. Shortness of breath, light-headedness, and disorientation were the most intensely reported symptoms. Approximately half (47%) of participants who received a hypercapnia training experience had a correlated symptom response during their subsequent hypercapnia testing session.
Conclusions: Although no significant training benefit was shown, becoming familiar with the sensations associated with hypercapnia under appropriate supervision could be useful to rebreather divers both recreationally and within occupational settings.

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.

Full article is available here - this is an immediate release article.

Technical diving accidents in France: a 15-year retrospective study reporting a high prevalence of musculoskeletal decompression sickness

Emmanuel Gouin1,2,3, Anaïs Caillard2,3, Colin Veses4, Marc Luciani5, Charlotte Lecomte6, Emmanuel Dugrenot1,2,7,8, François Guerrero2, Jean-Éric Blatteau9

¹ Divers Alert Network, Durham, NC, United States
² University Brest, Laboratory ORPHY EA 4324, IBSAM, Brest, France
³ CHRU La Cavale Blanche. Anesthesiology, perioperative and intensive care Units, Brest, France
⁴ Pasteur University Hospital, Hyperbaric Oxygen Therapy Department, Nice, France
⁵ Notre-Dame de la Miséricorde Hospital, Department of Hyperbaric Medicine, Ajaccio, France
⁶ Sainte Marguerite Hospital, APHM, Department of Hyperbaric Medicine, Marseille, France
⁷ Joint Department of Biomedical Engineering, The University of North Carolina and North Carolina State University, Chapel Hill, NC, USA
⁸ Subaquatic Operational Research Team (ERRSO), Military Institute of Biomedical Research (IRBA), Toulon, France
⁹ Military Teaching Hospital Sainte-Anne, Department of Hyperbaric Medicine and Diving Expertise, Toulon, France

Corresponding author: Dr Emmanuel Gouin, Laboratoire ORPHY, EA 4324, Université de Bretagne Occidentale, 6 Av. Le Gorgeu, 29200 BREST, France
ORCiD: 0000-0003-3691-5870
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Diving incidents; Gas-toxicity; Helium; Mixed-gas; Pulmonary oedema; Rebreather; Sport injuries

Abstract
(Gouin E, Caillard A, Veses C, Luciani M, Lecomte C, Dugrenot E, Guerrero F, Blatteau J-É. Technical diving accidents in France: a 15-year retrospective study reporting a high prevalence of musculoskeletal decompression sickness. Diving and Hyperbaric Medicine. 2026 30 June;56(2):125−136. doi: 10.28920/dhm56.2.125-136. PMID: 42290572.)
Introduction: Technical diving, involving rebreathers and/or helium-based gas mixtures for deeper and longer dives, may influence risk and clinical presentation of injuries due to helium’s properties, equipment constraints, or exposure conditions. This study aims to describe the specific characteristics of this accidentology.
Methods: A retrospective study was conducted across five French coastline hyperbaric units. Medical records of technical divers presenting with decompression sickness (DCS), immersion pulmonary oedema (IPO), or gas-toxicity between 2010 and 2024 were reviewed.
Results: 127 technical divers were included, three declined participation, leaving 124 cases for analysis. DCS was the most frequent condition (n = 105) followed by IPO (n = 16) and gas toxicity (n = 3). Median age was 45 [IQR 37–53] years, and 113 (91%) were male. Rebreathers were used in 94 (75.8%) cases and helium-based mixtures in 77 (62%). Previous diving-related accidents were reported in 36 (29%) cases. IPO occurred mainly after shallower dives in wetsuits and was frequently associated with procedural errors. Among DCS cases isolated musculoskeletal DCS predominated (n = 36), whereas spinal involvement was less frequent. When indicated, median recompression delay was 238 [IQR 135–555] minutes. Unfavourable outcomes occurred in 26 (25%) DCS cases, primarily with bone or inner-ear involvement.
Conclusions: Technical diving accidents exhibit distinct patterns from recreational diving, notably greater musculoskeletal involvement and a possible increased risk of dysbaric osteonecrosis (DON). Current evidence does not support different management, but the risk of potential initially silent bone lesions should not be overlooked. Further research on helium-related risks and hyperbaric treatment’s role in DON prevention is needed.

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.

The full article is currently under embargo for 12 months and will be made available on our website and PMC after this period. If you would like to access the article before it becomes publicly available, you can purchase it for personal use directly on our website. Alternatively, you may join SPUMS or EUBS to gain access to the entire issue.

Measuring whole-body inert gas uptake and washout during submersion

Oscar Plogmark^1,2, Kristian Soltesz³, Carl Hjelte^1,2,4, Oskar Frånberg^1,5

¹ Lund University, Faculty of Medicine, Department of Clinical Sciences Lund, Respiratory Medicine and Allergology, Lund, Sweden
² Swedish Armed Forces Diving and Naval Medicine Center, Swedish Armed Forces, Karlskrona, Sweden
³ Lund University, Faculty of Engineering, Department of Automatic Control, Lund, Sweden
⁴ Kungälv Hospital, Department of Anesthesia and Intensive care, Kungälv, Sweden
⁵ Blekinge Institute of Technology, Department of Mathematics and Natural Science, Karlskrona, Sweden

Corresponding author: Dr Oscar Plogmark, Sölvegatan 19, 221 85 Lund, Sweden
ORCiD: 0009-0008-3230-8807
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Decompression sickness; Diving research; Gas kinetics; Nitrogen; Physiology; Pressure

Abstract
(Plogmark O, Soltesz K, Hjelte C, Frånberg O. Measuring whole-body inert gas uptake and washout during submersion. Diving and Hyperbaric Medicine. 2026 30 June;56(2):137−147. doi: 10.28920/dhm56.2.137-147. PMID: 42290573.)
Introduction: Quantifying inert gas uptake and washout is critical for understanding decompression sickness (DCS). However, the limited amount of data has made it difficult to integrate inert gas kinetics into risk models for DCS. Measuring whole-body inert gas kinetics during submersion is technically challenging. This study presents a novel method for quantifying inert gas uptake and washout in human divers using a rebreather-based system.
Methods: During constant-depth diving with a closed-circuit system that maintains a constant oxygen partial pressure, changes in buoyancy will reflect the kinetics of inert gas. Two divers completed four dives each, with a bottom phase at 2.5 bar and a decompression phase at 1.3 bar or 1.4 bar. Load cell data were converted into equivalent changes in volume of nitrogen standardised for temperature and pressure (V_N2, STP). Power analysis was conducted to quantify the resolution by which the method could detect nitrogen uptake and washout volumes.
Results: Distinct uptake and washout curves were obtained, comparable to previous studies using other techniques. Mean V_N2 uptake during the bottom phase was 0.96 L (SD 0.29), while mean washout during decompression was 0.67 L 
(SD 0.26). The minimal mean detectable difference (MDD) with eight dives was 0.28 L for the bottom phase and 0.26 L for the decompression phase, considering standard 80% power and a 0.05 significance level.
Conclusions: This novel method quantifies inert gas kinetics during submersion with acceptable precision and accuracy. It could facilitate the collection of inert gas kinetics data during submersion, potentially yielding valuable correlations with the risk of DCS.

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.

The full article is currently under embargo for 12 months and will be made available on our website and PMC after this period. If you would like to access the article before it becomes publicly available, you can purchase it for personal use directly on our website. Alternatively, you may join SPUMS or EUBS to gain access to the entire issue.

Real-world experience of transoesophageal echocardiography for detection of clinically significant persistent foramen ovale

Peter Wilmshurst¹, Matthew Pearson², Kevin Walsh^3,4, W Lindsay Morrison⁵

¹ United Kingdom Diving Medical Committee (UKDMC), United Kingdom
² Shrewsbury and Telford NHS Hospital Trust, Shrewsbury SY3 8XQ, United Kingdom
³ University College Dublin, Dublin, Ireland
⁴ Our Lady’s Hospital for Sick Children, Dublin 12, Ireland
⁵ Liverpool Heart & Chest Hospital, Liverpool L14 3PE, United Kingdom

Corresponding author: Dr Peter Wilmshurst United Kingdom Diving Medical Committee, United Kingdom
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Bubbles; Decompression sickness; Diving; Echocardiography; Persistent foramen ovale; Stroke; Transcatheter closure

Abstract
(Wilmshurst P, Pearson M, Walsh K, Morrison WL. Real-world experience of transoesophageal echocardiography for detection of clinically significant persistent foramen ovale. Diving and Hyperbaric Medicine. 2026 30 June;56(2):148−153. doi: 10.28920/dhm56.2.148-153. PMID: 42290574.)
Introduction: Transoesophageal echocardiography (TOE) is claimed to be the investigation of choice for detecting a persistent foramen ovale (PFO) with almost 100% diagnostic accuracy. If true, TOE would detect all large/clinically significant PFOs.
Methods: Retrospective analysis to determine the sensitivity of TOE for detection of clinically significant PFOs. Patients were from a consecutive series of 150 patients who had transcatheter closure of a PFO following events attributed to paradoxical embolism (decompression sickness or stroke). In each patient, transthoracic echocardiogram with bubble contrast showed a clinically significant atrial right-to-left shunt. The data reported are from the sub-group of the 150 patients with a clinically significant PFO who also had a TOE performed in other hospitals.
Results: Twenty seven of 150 consecutive patients had a total of 31 TOEs performed at 22 United Kingdom regional cardiac centres. TOE failed to detect a PFO in 17 of the 27 patients. Four patients had a TOE on two separate occasions and in each case both of the TOEs failed to show a PFO. TOE gave a false negative test in 21 of 31 investigations (sensitivity 32%). The mean PFO diameter was 9.4 mm (median 9 mm, range 5−16 mm) in the 21 patients in whom balloon sizing was performed and 9.8 mm (median 10 mm, range 5−16 mm) in the 13 patients in whom balloon sizing was performed and a TOE failed to show a PFO.
Conclusions: These finding demonstrate that the precision of TOE for detecting a PFO in real world clinical practice is considerably lower than generally believed.

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.

Full article is available here - this is an immediate release article.

Quantifying discrepancy between indicated and actual oxygen flow rates delivered by Comweld Ezi-flow low and standard flowmeters under hyperbaric conditions: a technical report

Yoav Aufgang^1,2, Bridget Devaney^1,3,4, Jason Chan^1,2, Ian Millar^1,4, Theo Tsouras¹

¹ Department of Intensive Care and Hyperbaric Medicine, Alfred Health, Melbourne, Australia
² School of Translational Medicine, Faculty of Medicine Nursing and Health Sciences, Monash University, Melbourne, Australia
³ Emergency and Trauma Centre, Alfred Health, Melbourne, Australia
⁴ School of Public Health and Preventive Medicine, Faculty of Medicine Nursing and Health Sciences, Monash University, Melbourne, Australia

Corresponding author: Dr Bridget Devaney, Department of Intensive Care and Hyperbaric Medicine, Alfred Health, 55 Commercial Road, Melbourne, VIC 3004, Australia
ORCiD: 0000-0001-6521-418X
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Flow dynamics; Gas flow; Hyperbaric environment; Hyperbaric oxygen treatment; Medical equipment

Abstract
(Aufgang Y, Devaney B, Chan J. Millar I, Tsouras T. Quantifying discrepancy between indicated and actual oxygen flow rates delivered by Comweld Ezi-flow low and standard flowmeters under hyperbaric conditions: a technical report. Diving and Hyperbaric Medicine. 2026 30 June;56(2):154−160. doi: 10.28920/dhm56.2.154-160. PMID: 42290575.)
Introduction: During clinical use of extracorporeal membrane oxygenation (ECMO) in hyperbaric conditions at our centre, upward titration of indicated sweep gas flow rates is required to maintain adequate CO2 clearance. This project measured the impact of hyperbaric pressure on oxygen flow rates delivered by the Comweld Ezi-Flow flowmeters used in our centre. 
Methods: Oxygen flow rates through Comweld Ezi-flow standard and low oxygen gas flowmeters were set at 101.3 kPa (1 atmosphere absolute [atm abs]) and then measured at intervals up to 284 kPa (2.8 atm abs) using a calibrated gas flow analyser, with cross verification against a small Douglas bag test type apparatus. During testing, the chamber was compressed and decompressed at a rate of 10 kPa·min^-1. Flow rates during chamber compression and decompression were compared.
Results: The indicated rate of oxygen gas flow through the unadjusted flowmeters changed minimally – typically rising by a maximum of half of the diameter of the indicator ball. The actual (volumetric) flow, tested across indicated flow rates from 3 to 12 L·min^-1, was consistently reduced by approximately 50% as the chamber pressure increased from 101.3 to 284 kPa (1 to 2.8 atm abs). A slightly smaller reduction was observed when assessing the low flowmeter across the same pressure range; reductions of 40.0 and 43.3% were demonstrated at 0.3 to 0.6 L·min^-1 respectively. Differences in flow rates between compression and decompression were minor except at the very lowest flows.
Conclusions: At 284 kPa (2.8 atm abs), actual volumetric flow of oxygen through Comweld Ezi-Flow flowmeters is dramatically reduced and this needs appropriate compensation to ensure therapeutic aims are achieved.

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.

The full article is currently under embargo for 12 months and will be made available on our website and PMC after this period. If you would like to access the article before it becomes publicly available, you can purchase it for personal use directly on our website. Alternatively, you may join SPUMS or EUBS to gain access to the entire issue.

Bipolar spectrum disorders in divers: risks, recognition, and recommendations

Abraham L Querido^1,2, Thijs T Wingelaar^2,3

¹ Praktijk Querido, Hilversum, the Netherlands
² Dutch Society of Diving and Hyperbaric Medicine, Bilthoven, the Netherlands
³ Royal Netherlands Navy, Diving Medical Center, Den Helder, the Netherlands

Corresponding author: Dr Abraham L Querido, Praktijk Querido, Veerstraat 25, 1211 HJ Hilversum, the Netherlands
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Bipolar disorder; Diving; Executive function; Psychotropic drugs; Risk assessment

Abstract

(Querido AL, Wingelaar TT. Bipolar spectrum disorders in divers: risks, recognition, and recommendations. Diving and Hyperbaric Medicine. 2026 30 June;56(2):170−176. doi: 10.28920/dhm56.2.170-176. PMID: 42290577.)
Bipolar disorder is a recurrent psychiatric condition characterised by episodic mood disturbances, residual functional impairment, and high rates of psychiatric and medical comorbidity. While many individuals achieve symptomatic remission, persistent deficits in cognition, emotional regulation, and insight may remain, raising concerns for participation in safety-critical activities such as scuba diving. This systematic review synthesised evidence from psychiatric, occupational, aviation, and diving medicine literature to examine the clinical course of bipolar disorder, treatment considerations, functional outcomes, and safety-relevant factors pertinent to fitness-to-dive assessments. Bipolar disorder exhibits marked heterogeneity in syndromal and functional outcomes. Even during euthymia, subtle impairments in attention, executive functioning, and decision-making may persist. Pharmacological stability is essential for diving, but treatment regimens, particularly lithium use, polypharmacy, and antidepressant therapy, introduce additional considerations. Comorbidity, circadian disruption, sleep deprivation, and reduced insight during early relapse further complicate risk assessment. Empirical data on diving outcomes in individuals with bipolar disorder are scarce, necessitating reliance on expert opinion and extrapolation from related safety-critical domains. Fitness-to-dive assessments in bipolar disorder should prioritise sustained functional stability, reliable treatment adherence, and illness insight over symptom absence alone. A cautious, individualised approach is warranted, incorporating medication effects, comorbidity, operational context, and relapse-prevention planning, supported by collaboration between mental health professionals and diving medical examiners.

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.

The full article is currently under embargo for 12 months and will be made available on our website and PMC after this period. If you would like to access the article before it becomes publicly available, you can purchase it for personal use directly on our website. Alternatively, you may join SPUMS or EUBS to gain access to the entire issue.

Evidence‑informed decision aid for fitness‑to‑dive assessment after otologic surgery

Juan Riestra-Ayora^1,2, Carlos Fernández-Navarro², Eduardo Martín-Sanz^1,2, Manuel F Salvador-Marín^3,4

¹ Department of Medicine, Faculty of Biomedical and Health Sciences, Universidad Europea de Madrid, Villaviciosa de Odón, Madrid, Spain
² Department of Otolaryngology-Head and Neck Surgery, Hospital Universitario de Getafe, Getafe, Madrid, Spain
³ Department of Hyperbaric Medicine, Hospital General Universitario de Castellón, Castellón de la Plana, Castellón, Spain
⁴ Department of Medicine, Faculty of Health Sciences, Universitat Jaume I, Castellón de la Plana, Spain

Corresponding author: Dr Juan Riestra-Ayora, Department of Otolaryngology-Head and Neck Surgery, Hospital Universitario de Getafe, Getafe, 28905, Madrid, Spain
ORCiD: 0000-0003-0297-2711
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Diving; Barotrauma; Cochlear implants; Ear diseases; Ear, middle; Otorhinolaryngologic surgical procedures; Stapedectomy

Abstract
(Riestra-Ayora J, Fernández-Navarro C, Martín-Sanz E, Salvador-Marín MF. Evidence‑informed decision aid for fitness‑to‑dive assessment after otologic surgery. Diving and Hyperbaric Medicine. 2026 30 June;56(2):177−184. doi: 10.28920/dhm56.2.177-184. PMID: 42290578.)
Introduction: Fitness-to-dive after otologic surgery is often approached conservatively, with some procedures historically labelled as absolute contraindications despite limited empirical evidence. The available literature is heterogeneous and includes clinical reports, experimental pressure studies, guidance documents, and manufacturer specifications, leading to uncertainty in clinical counseling. We aimed to characterise the available evidence regarding fitness-to-dive after otologic surgery and to develop an evidence-informed clinical decision aid.
Methods: A scoping review was conducted in accordance with PRISMA-ScR guidance. PubMed/MEDLINE, Embase, Scopus, and relevant non-indexed sources were searched. Eligible sources included clinical reports and series, experimental or hyperbaric chamber studies, guidance or consensus documents, and manufacturer statements providing explicit pressure- or depth-related information. Data were charted descriptively by procedure type and evidence stream.
Results: The search identified 324 records; after removal of duplicates and screening, 40 sources were included. The evidence base was predominantly non-comparative. Across procedures, recommendations emphasised postoperative stability and reliable pressure equalisation rather than surgical history alone. Canal wall down mastoidectomy was consistently portrayed as incompatible with diving, whereas selected middle ear reconstructions and stapes surgery were commonly described as potentially compatible in appropriately selected individuals. For cochlear implantation, guidance was mainly conditional and based on hyperbaric testing, limited clinical diving reports, and manufacturer-specified pressure or depth limits. Communication emerged as an additional practical consideration in cases of significant hearing loss.
Conclusions: Relevant evidence is limited and heterogeneous, and does not consistently support blanket prohibitions for all otologic procedures. A function-based, individualised approach is supported, while specific higher-risk scenarios warrant restriction. Prospective registries and standardised outcome reporting are needed to refine procedure-specific recommendations.

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.

Full article is available here - this is an immediate release article.

Recreational and technical rebreather fatalities and diving safety status

Frauke Tillmans^1,2, Camilo Saraiva¹, Sherri Ferguson^1,3, Emmanuel Dugrenot^1,2, S Lesley Blogg^1,4

¹ Divers Alert Network, 6 West Colony Place, Durham, NC, USA
² UNC-NC State Joint Department of Biomedical Engineering, Chapel Hill, NC, USA
³ Shanfe Research and Consulting Ltd, North Vancouver, British Columbia, Canada
⁴ SLB Consulting, Kirkby Stephen, Cumbria, UK

Corresponding author: Dr Frauke Tillmans, Divers Alert Network, 6 West Colony Place, Durham, NC 27705, USA
ORCiD: 0000-0002-2159-0834
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Accidents; Death rate; Demographics; Global use; Rebreather diving; Technical diving

Abstract
(Tillmans F, Saraiva C, Ferguson S, Dugrenot E, Blogg SL. Recreational and technical rebreather fatalities and diving safety status. Diving and Hyperbaric Medicine. 2026 30 June;56(2):185−190. doi: 10.28920/dhm56.2.185-190. PMID: 42290579.)
Introduction: The Divers Alert Network (DAN) aims to provide safety information for all types of diving. Assessing the number of active closed-circuit rebreather (CCR) divers is difficult, as pertinent information is often not available. This review aims to give an overview of global use and safety of CCR diving equipment from 2013–2022.
Methods: Data were combined and assessed from various DAN internal and public sources on CCR diver demographics, fatalities, and CCR sales.
Results: Over the past 10 years, the number of certified CCR divers has increased from an estimated 2,000 in 2013, to 3,000 in 2022. There has been an increase in growth in CCR sales over a five-year period from 2018, with around 25,000 to 35,000 units on the market today; rebreather divers are a growing community. There were 241 confirmed CCR fatalities from 2013–2022, mean 24 (SD 6) per year. Most fatal accidents involved dives made between 40–80 m (130–260 ft) depth. Cause of death is difficult to establish due to lack of detail and dive-specific training for the medical examiner. The estimated death rate is 1.8–3.8 deaths per 100,000 CCR dives although these values are derived from limited data.
Conclusions: Not enough information is made available to address CCR accident analysis effectively, perhaps stemming from family reticence to discuss the incident, fear of litigation, and/or lack of diving knowledge reducing the useful information. DAN continues to collect CCR data, but increased collaboration between training bodies, equipment providers, and comprehensive reporting of incidents is needed to reveal the true picture.

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.

The full article is currently under embargo for 12 months and will be made available on our website and PMC after this period. If you would like to access the article before it becomes publicly available, you can purchase it for personal use directly on our website. Alternatively, you may join SPUMS or EUBS to gain access to the entire issue.

The role of hyperbaric oxygen treatment in a case of pyomyositis

Jobin G Bose¹, Subhranshu Kumar¹, Sunil Anand², Chandrasekhar Mohanty¹

¹ Department of Marine Medicine, Institute of Naval Medicine, INHS Asvini, Mumbai, India
² Department of Plastic and Reconstructive Surgery, Institute of Naval Medicine, INHS Asvini, Mumbai, India

Corresponding author: Dr Jobin Bose, Department of Marine Medicine, Institute of Naval Medicine, INHS Asvini, Mumbai, Pin-400005, India
ORCiD: 0009-0007-5758-5926
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Case reports; Hypoxia; Musculo-skeletal; Wounds

Abstract

(Bose JG, Kumar S, Anand S, Mohanty C. The role of HBOT in a case of pyomyositis. Diving and Hyperbaric Medicine. 2026 30 June;56(2):191−194. doi: 10.28920/dhm56.2.191-194. PMID: 42290580.)
Pyomyositis is a serious bacterial infection of the skeletal muscles, usually treated with antibiotics and surgical drainage. The success of medical or surgical treatment is often delayed or less effective when tissue hypoxia is present. Hyperbaric oxygen therapy (HBOT) is currently being studied as a helpful additional treatment for various conditions, especially those involving complications of tissue hypoxia. In this case report, we describe a 29-year-old male who developed chronic pyomyositis and a right lower leg ulcer after failure of multiple surgeries, including fasciotomy, debridements, skin grafts and antibiotics to treat compartment syndrome and tuberculosis of the right knee. HBOT was administered for 80 sessions at 243 kPa (2.4 atmospheres absolute) for 90 minutes. The patient showed significant clinical improvement, as evidenced by the development of healthy granulation tissue, reduction in swelling and discharge, and better mobility. This case highlights the potential of HBOT as an additional treatment option for complex soft tissue infections such as pyomyositis caused by tuberculosis, especially in cases where traditional treatments have been ineffective.

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.

The full article is currently under embargo for 12 months and will be made available on our website and PMC after this period. If you would like to access the article before it becomes publicly available, you can purchase it for personal use directly on our website. Alternatively, you may join SPUMS or EUBS to gain access to the entire issue.

Spontaneous resolution of choroidal neovascular membrane in the fellow eye during hyperbaric oxygen treatment for retinal artery occlusion: a case report

Umut Dağ¹, Betül Dertsiz Kozan¹, Selim Engin Egeren², Hasan Öncül¹, Mehtap Çağlayan¹, Mehmet Fuat Alakuş¹

¹ Department of Ophthalmology, Gazi Yasargil Training and Research Hospital, Diyarbakır, Türkiye
² Department of  Hyperbaric and Underwater Medicine, Gazi Yasargil Training and Research Hospital, Diyarbakır, Türkiye

Corresponding author: Dr Betül Dertsiz Kozan, Department of Ophthalmology, Gazi Yasargil Training and Research Hospital, Diyarbakır, Türkiye
ORCiD: 0000-0002-0667-2866
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Choroidal neovascularization; Hyperbaric oxygenation; Visual acuity

Abstract

(Dağ U, Dertsiz Kozan B, Engin Egeren S, Öncül H, Çağlayan M, Fuat Alakuş M. Spontaneous resolution of choroidal neovascular membrane in the fellow eye during hyperbaric oxygen treatment for retinal artery occlusion: a case report. Diving and Hyperbaric Medicine. 2026 30 June;56(2):195−197. doi: 10.28920/dhm56.2.195-197. PMID: 42290581.)
Retinal artery occlusion (RAO) is an ophthalmic emergency that causes sudden, painless vision loss due to retinal ischaemia. Hyperbaric oxygen therapy (HBOT), when initiated early, may help preserve photoreceptor function by increasing retinal oxygenation. A 69-year-old woman with a history of hypertension presented with sudden visual loss in the left eye and was diagnosed with RAO. HBOT was initiated within six hours of symptom onset (253 kPa [2.5 atmospheres absolute] for 90 minutes per session), and 20 sessions were planned. During the seventh session, the patient reported a marked improvement in visual acuity in the contralateral (right) eye, previously diagnosed with choroidal neovascular membrane (CNVM) and untreated with anti-vascular endothelial growth factor (VEGF) therapy. Optical coherence tomography demonstrated regression of the CNVM and complete resolution of subretinal fluid. To our knowledge, this is the first report suggesting that HBOT administered for unilateral RAO may also promote structural and functional improvement of CNVM in the contralateral eye.

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.

Full article is available here - this is an immediate release article.

Cerebral arterial oxygen embolism as a complication of hyperbaric oxygen treatment: a case report

Rahulkumar Ramchandani¹, Bridget Devaney^1,2,3, Ashish Jaison^1,2,3, Neil Banham⁴, Stephan Roehr^1,5

¹ Department of Intensive Care and Hyperbaric Medicine, Alfred Health, Melbourne, 3004, Victoria, Australia
² Emergency and Trauma Centre, Alfred Health, Melbourne, Australia
³ Department of Epidemiology and Preventative Medicine, Monash University, Melbourne, Australia
⁴ Department of Hyperbaric Medicine, Fiona Stanley Hospital, Perth, Australia
⁵ Townsville University Hospital Hyperbaric Medicine Unit, Queensland, Australia

Corresponding author: Dr Bridget Devaney, Head of Hyperbaric Medicine, Department of Intensive Care and Hyperbaric Medicine, Alfred Health, 55 Commercial Road, Melbourne, VIC 3004, Melbourne, Australia
ORCiD: 0000-0001-6521-418X
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Adverse event; Birt-Hogg-Dubé syndrome; Cerebral arterial gas embolism; Oxygen bubble embolus; Pulmonary barotrauma; Lung cysts

Abstract

(Ramchandani R, Devaney B, Jaison A, Banham N, Roehr S. Cerebral arterial oxygen embolism as a complication of hyperbaric oxygen treatment: a case report. Diving and Hyperbaric Medicine. 2026 30 June;56(2):198−202. doi: 10.28920/dhm56.2.198-202. PMID: 42290582.)
Cerebral arterial gas embolism (CAGE) is a recognised complication of diving-related barotrauma and of medical procedures whereby gas enters the vascular system. CAGE is a principal indication for hyperbaric oxygen treatment (HBOT). In contrast, CAGE resulting from HBOT itself is exceedingly rare. We describe the case of a 73-year-old man undergoing his first session of HBOT for a chronic lower limb wound, who developed acute focal neurological deficits during decompression. He had no known respiratory disease or smoking history. Immediate assessment demonstrated stable physiology. Initial computed tomography (CT) scan of the brain and neck vessels and perfusion imaging did not show any evidence of thrombus or intravascular gas, and partial neurological recovery occurred over several hours. Subsequent magnetic resonance imaging of the brain demonstrated acute infarction involving the left precentral and postcentral gyri. High-resolution CT chest revealed multiple bilateral thin-walled pulmonary cysts, including a left upper lobe cyst with an air–fluid level consistent with recent barotrauma. A transient broncho-venous fistula allowing arterial oxygen embolisation during decompression was considered the most plausible mechanism. The patient improved with supportive management and was discharged with minimal residuae. This case highlights an exceptionally rare but serious complication of HBOT and underscores the importance of vigilance during decompression and careful consideration of occult pulmonary pathology.

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.

The full article is currently under embargo for 12 months and will be made available on our website and PMC after this period. If you would like to access the article before it becomes publicly available, you can purchase it for personal use directly on our website. Alternatively, you may join SPUMS or EUBS to gain access to the entire issue.

Returning to diving and hyperbaric exposure after pulmonary vein isolation for atrial fibrillation

Silvio Zerbi¹, Luigi Tarsia², Vincenzo Benenati³, Dario Nicosia⁴, Gerardo Bosco⁵, Matteo Paganini²

¹ Department of Anesthesiology and Intensive Care, ASST Sette Laghi, Varese, Italy
² Independent Researcher, Padova, Italy
³ Anesthesiology, Intensive Care and Hyperbaric Medicine, Policlinico Universitario “P. Giaccone”, Palermo, Italy
⁴ UOC Centrale Operativa 118, ARNAS Civico, Palermo, Italy
⁵ Department of Medicine and Aging Sciences, University “G. D’Annunzio” Chieti – Pescara, Italy

Corresponding author: Dr Silvio Zerbi, Department of Anesthesiology and Intensive Care. ASST Sette Laghi, Viale Borri, 57 – 21100 Varese (VA), Italy
ORCiD: 0009-0004-4280-432X
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Catheter ablation; Electrocardiography; Electrophysiology; Diving medicine; Hyperbaric oxygen; Hyperbaric medicine; Implantable loop recorder

Abstract

(Zerbi S, Tarsia L, Benenati V, Nicosia D, Bosco G, Paganini M. Returning to diving and hyperbaric exposure after pulmonary vein isolation for atrial fibrillation. Diving and Hyperbaric Medicine. 2026 30 June;56(2):203−207. doi: 10.28920/dhm56.2.203-207. PMID: 42290583.)
Pulmonary vein isolation (PVI) is an established rhythm-control therapy for atrial fibrillation (AF), yet the electrophysiological response of post-PVI individuals exposed to hyperbaric environments remains undocumented. Similarly, the in-vivo performance of implantable loop recorders (ILRs) and external patch-based electrocardiographic (ECG) devices under increased ambient pressure has never been reported. We describe the first hyperbaric electrophysiology assessment in a post-PVI diver undergoing both underwater immersion and dry hyperbaric exposure with dual-modality cardiac rhythm monitoring. A 46-year-old experienced diver with successful PVI underwent: a scuba dive to 42 m in a warm water pool, monitored with a marinised 12-lead ECG Holter system; and a stepwise hyperbaric chamber compression to 284 kPa 
(2.8 atmospheres absolute) in ambient air, with single-lead surface ECG recordings obtained at static pressure plateaus. In both cases, the subject was monitored as well by his ILR. No AF recurrence or other dysrhythmias were detected during either exposure, with stable heart rate trends. The ILR maintained full functional integrity after both the 42 m dive and the 284 kPa chamber compression. The external ECG patch yielded interpretable tracings during static phases. Telemetry failed due to electromagnetic shielding by the steel chamber walls. This case suggests that carefully selected post-PVI individuals may tolerate controlled underwater and hyperbaric exposure without rhythm destabilisation. Both implantable and external monitoring devices preserved operational integrity under moderate hyperbaric conditions, providing a foundation for the emerging field of hyperbaric electrophysiology monitoring and informing fitness-to-dive assessment in post-ablation patients.

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.