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Impact of neoprene wetsuits on lung volumes and work of breathing: implications for military diver safety and performance

Antoinette Houtkooper¹, Thijs T Wingelaar^1,2, Pieter-Jan AM van Ooij^1,3, Joost G van den Aardweg³

¹ Royal Netherlands Navy Diving and Submarine Medical Centre, Den Helder, the Netherlands
² Amsterdam UMC, location AMC, Department of Anaesthesiology, Amsterdam, the Netherlands
³ Amsterdam UMC, location AMC, Department of Pulmonology, Amsterdam, the Netherlands

Corresponding author: Antoinette Houtkooper, Royal Netherlands Navy Diving Medical Center, Rijkszee en Marinehaven, PO Box 10.000, 1780 CA Den Helder, the Netherlands
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Keywords
Airway resistance; Chest wall compression; Diving physiology; Forced oscillation technique; Lung volume

Abstract
(Houtkooper A, Wingelaar TT, van Ooij PJAM, van den Aardweg JG. Impact of neoprene wetsuits on lung volumes and work of breathing: implications for military diver safety and performance. Diving and Hyperbaric Medicine. 2026 30 September;56(3):218−225. doi: 10.28920/dhm56.3.218-225. PMID: 42743560.)
Introduction: Neoprene wetsuits may impose mechanical constraints on the chest wall, potentially altering respiratory function. This study investigated the impact of neoprene wetsuits on lung volumes, airway mechanics, and work of breathing (WOB) in healthy male divers.
Methods: A randomised crossover trial was conducted with 31 male divers at the Royal Netherlands Navy Diving Medical Centre. Participants underwent pulmonary function testing, including spirometry, body plethysmography, the forced oscillation technique (FOT), and diffusion capacity measurements, both with and without a hoodless standardised 5 mm neoprene full body wetsuit with a neoprene neck seal. Primary outcomes included changes in forced vital capacity (FVC), functional residual capacity (FRC), airway resistance (Raw), reactance (Xrs), and WOB.
Results: Wearing a neoprene wetsuit led to statistically significant reductions in FVC (2.8%, P < 0.05), forced expiration in one second (2.9%, P < 0.05), FRC (4.0%, P < 0.05), and expiratory reserve volume (10.9%, P < 0.05), alongside increases in inspiratory capacity and tidal volume. Raw increased significantly (P < 0.05), while the FOT revealed altered airway mechanics, evidenced by increased Xrs at multiple frequencies (P < 0.05). Diffusion capacity remained unchanged, suggesting preserved alveolar-capillary function.
Conclusions: Neoprene wetsuits induce mechanically restrictive effects on the chest wall, reducing static and dynamic lung volumes and increasing WOB. While these changes may not be clinically relevant at rest, their impact needs to be determined during strenuous or prolonged dives, particularly when combined with other equipment that limits thorax excursions. Future research should explore the effects of the military 5 mm wetsuit under immersed conditions to better understand their operational impact on diver performance and safety.

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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.

Occupational health challenges in commercial diving: a qualitative study of psychological risk, training gaps, and organisational responsibilities

Holly Blake^1,2, Basharat Hussain³, Lianne Hufton⁴, Elisha Cousins⁴, Graham Johnson^3,4, Andrew Tabner^3,4

¹ School of Health Sciences, University of Nottingham, Nottingham, UK
² NIHR Nottingham Biomedical Research Centre, Nottingham, UK
³ School of Medicine, University of Nottingham, Nottingham, UK
⁴ Emergency Department, University Hospitals of Derby and Burton NHS Foundation Trust, Derby, UK

Corresponding author: Professor Holly Blake, School of Health Sciences, University of Nottingham, Medical School, Queen’s Medical Centre, Nottingham, NG7 2HA, UK
ORCiD: 0000-0003-3080-2306
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Keywords
Occupational stress; Organisational policy; Qualitative research; Training

Abstract
(Blake H, Hussain B, Hufton L, Cousins E, Johnson G, Tabner A. Occupational health challenges in commercial diving: a qualitative study of psychological risk, training gaps, and organisational responsibilities. Diving and Hyperbaric Medicine. 2026 30 September;56(3):226−236. doi: 10.28920/dhm56.3.226-236. PMID: 42743561.)
Introduction: Little is known about the occupational health needs of commercial divers, particularly regarding psychological wellbeing, trauma exposure, organisational support, and the adequacy of training for high‑risk environments. This study qualitatively explored pathways into commercial diving, experiences of psychological strain and trauma, perceptions of support, and the relevance of training from the perspectives of divers, supervisors, and industry representatives.
Methods: This qualitative study used semi‑structured interviews and focus groups with purposively sampled participants (n = 20 men). Data were analysed using reflexive thematic analysis.
Results: Three themes were identified: (1) pathways into a high‑risk occupation shaped by financial incentives, risk acceptance, and informal entry routes; (2) psychological strain characterised by reported exposure to traumatic events, normalisation of distress, stigma surrounding mental health disclosure, and predominantly reactive organisational support; and (3) perceived inadequacies in training, described as generic, low‑fidelity, and insufficiently aligned with the operational realities of offshore and saturation diving, alongside limited opportunities to practise key skills, contributing to feelings of unpreparedness during emergencies.
Conclusions: Participants described commercial diving as associated with substantial and often unaddressed psychological burden, compounded by cultural stigma, structural barriers to help‑seeking, and predominantly reactive support systems. Training provision was perceived as outdated and insufficiently aligned with operational demands, with limited organisational investment in development. Findings suggest that industry‑wide efforts may be needed to implement proactive mental‑health strategies and improve the alignment of training with operational realities.

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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.

A calculation method for inert gas tension based on a multi-tissue model

Shuai Di¹, Chumeng Liu¹, Jinghua Gu¹

¹ Naval Medical Center, Naval Medical University, Shanghai, China

Corresponding author: Professor Jinghua Gu, 880 Xiangyin Road, Yangpu District, Shanghai, China
ORCiD: 0009-0007-9622-7822
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Keywords
Decompression; Decompression sickness; Diving; Diving medicine; Nitrogen; Pressure

Abstract
(Di S, Liu C, Gu J. A calculation method for inert gas tension based on a multi-tissue model. Diving and Hyperbaric Medicine. 2026 30 September;56(3):237−244. doi: 10.28920/dhm56.3.237-244. PMID: 42743562.)
Introduction: This study developed a mathematical model capable of accurately estimating inert gas tension within human tissues under continuously changing ambient pressure.
Methods: Based on Haldane’s decompression theory and a multi-tissue model, and grounded in the principle that the rate of gas diffusion is proportional to the pressure gradient, a differential equation was derived and solved. Analytical solutions were obtained for four prototypical ambient pressure patterns: constant pressure, exponential compression, linear compression, and linear decompression. The model’s validity was confirmed by comparison with the piecewise approximation method using a sufficiently small step interval.
Results: The model allows precise calculation of theoretical tissue inert gas tension at any given time. In air-breathing fast buoyant ascents, for fast tissues with half-times of 30 s and 80 s, the inert gas tensions calculated using the conventional method (374 kPa and 233 kPa) were notably higher than those obtained via the proposed model (331 kPa and 217 kPa), with a maximum difference of 13%. The proposed model closely matched the piecewise method (1 s interval), differing by only 1 kPa. For tissue half-times exceeding 5 min, all three methods produced similar results. In a standard air diving decompression schedule, both the proposed and conventional methods yielded initial decompression stop depths rounded to 18 m, showing no significant difference.
Conclusions: The model demonstrates clear advantages for fast tissues, and under varying ambient pressures, establishes a theoretical foundation for the dynamic prediction of tissue inert gas tension across diverse diving scenarios. It can be utilised in safety assessments of fast buoyant ascent, offering substantial theoretical relevance and practical applicability.

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A feasibility study of combined hyperbaric oxygen treatment and a lifestyle medicine program for multimorbid conditions

Elizabeth Elliott¹, Sam Manger², John Mercer³, John Stevens⁴

¹ Department of Diving and Hyperbaric Medicine, Royal Hobart Hospital, Hobart, Tasmania, Australia
² James Cook University College of Medicine and Dentistry, Douglas, Queensland, Australia
³ Allied Health Metabolic Clinic, Tasmania Health Service, Launceston, Tasmania, Australia
⁴ Mullumbimby, New South Wales, Australia

Corresponding author: Dr Elizabeth Elliott, Department of Diving and Hyperbaric Medicine, Royal Hobart Hospital, Liverpool St, Hobart, Tasmania 7000, Australia
ORCiD: 0009-0005-3679-621X
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Keywords
Education; Health; Hyperbaric research; Medical conditions and problems; Questionnaire

Abstract
(Elliott E, Manger S, Mercer J, Stevens J. A feasibility study of combined hyperbaric oxygen treatment and a lifestyle medicine program for multimorbid conditions. Diving and Hyperbaric Medicine. 2026 30 September;56(3):245−256. doi: 10.28920/dhm56.3.245-256. PMID: 42743563.)
Introduction: Multimorbidity and polypharmacy are highly prevalent among patients receiving hyperbaric oxygen treatment (HBOT). Lifestyle Medicine (LM) interventions improve health outcomes in chronic disease management, but their implementation in tertiary hospital settings remains poorly studied and not at all in hyperbaric therapy. We evaluated the feasibility and acceptability amongst patients and staff of delivering a Lifestyle Medicine Program (LMP) within a small hyperbaric medicine department.
Methods: A six-week, open-label, feasibility study was conducted at the Department of Diving and Hyperbaric Medicine, Royal Hobart Hospital. The LMP comprised weekly group education sessions on the six pillars of LM, underpinned by motivational interviewing, and supported by newsletters. Acceptability (participant satisfaction ratings, recommendation rates, perceived value) and feasibility (enrolment, session attendance, retention, engagement, resource use, cost analysis, program delivery, and safety) were assessed via mixed methods data analysis on participant and staff feedback through questionnaires and focus groups. 
Results: Twelve patients were recruited via rolling recruitment; 11 completed post-program questionnaires. Participants perceived the LMP as acceptable, safe, and valuable, with 11/11 recommending the program and 10 reporting it beneficial.  Qualitative themes from short answers and focus groups indicated that the group-based education fostered social connection and self-agency, though challenges in accessibility, program framing, and therapeutic alliance with HBOT highlighted areas for improvement to enhance feasibility and integration within clinical care. Seventeen staff completed their questionnaire, indicating that the LMP was perceived as beneficial, valuable, and achievable with the hyperbaric setting, provided that minor logistical and structural modifications are made.
Conclusions: Delivering a LMP alongside HBOT is feasible in a tertiary hospital setting, with potential to enhance patient wellbeing and complement clinical care. Larger, multi-site trials are needed to evaluate scalability, inclusivity, and long-term feasibility outcomes.

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No difference in core temperature or thermal sensation in male and female scuba divers using wetsuits or semi-drysuits in 22.6°C sea water

Fabian N Möller^1,2,3, Kavi Dodge¹, Tucker Orman², Igor Glavičić⁴, Željko Dujić⁵, Nikola Foretić⁶, Andrew T Lovering¹

¹ University of Oregon, Department of Human Physiology, Eugene, OR, USA
² Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, Aerospace Physiology Lab, Boston, MA, USA
³ German Sport University, Cologne, Institute of Professional Sport Education and Sport Qualification, Cologne, Germany
⁴ Department of Marine Studies, University of Split, Croatia
⁵ Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
⁶ Faculty of Kinesiology, University of Split, Split, Croatia

Corresponding author: Professor Andrew Lovering, Department of Human Physiology, 1240 University of Oregon, Eugene OR, 97403-1240, USA
ORCiD: 0000-0001-7826-4290
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Keywords
Dive suit; Equipment; Immersion; Safety; Scuba diving; Thermal protection

Abstract
(Möller FN, Dodge K, Orman T, Glavičić I, Dujić Z, Foretić N, Lovering AT. No difference in core temperature or thermal sensation in male and female scuba divers using wetsuits or semi-drysuits in 22.6°C sea water. Diving and Hyperbaric Medicine. 2026 30 September;56(3):257−264. doi: 10.28920/dhm56.3.257-264. PMID: 42743564.)
Introduction: Scuba diving in water below thermoneutral temperature (< 30°C) can reduce core temperature and impair comfort and performance. Semi-drysuits are presumed superior to wetsuits because they presumably limit water entry into the suits, but changes in core temperature and thermal sensation have not been previously published in males and females wearing semi-drysuits. This study assessed the influence of anthropometrics and thermal protection from wetsuits and semi-drysuits on core temperature and thermal sensation in males and females performing recreational scuba dives.
Methods: Core temperature (telemetric pill) and thermal sensation (Young’s scale) were measured in 39 recreational divers (17 females) wearing wetsuits (mean 6 [SD 1] mm thickness, n = 19, 6 females) or semi-drysuits (7 [1] mm, n = 20, 11 females) during a 45-minute dive in mean 22.6 (1.1)°C water.
Results: The wetsuit group had approximately 2 mm thinner suits (P < 0.001) and a 0.2 m² greater body surface area (P = 0.035), while age, body mass index, body fat percentage, and water temperature did not differ between groups. No significant differences were observed between suit types for absolute core temperature change or thermal sensation. In semi-drysuit divers, body fat percentage negatively correlated with the change in temperature per minute of dive time (rate of temperature change, R² = 0.29, P = 0.014). However, when anthropometric values were multiplied by suit thickness, there were no significant correlations with the rate of temperature change in either suit type.
Conclusions: Semi-drysuits did not confer superior thermal protection in 22.6°C water during recreational scuba diving activities.

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Microbiological monitoring of scuba cylinders under routine filling and seasonal diving conditions

Recep Özkan¹, Osman Turkmen², Elif Okumuş³, Sukran Özhan⁴, Hasan Sivrikaya², Ese Başbulut⁵, Kübra Ozgok Kangal⁶

¹ Department of Hyperbaric and Diving Medicine, Ataturk University Erzurum, Türkiye
² Department of Hyperbaric and Diving Medicine, Samsun Training and Research Hospital, Samsun, Türkiye
³ Department of Medical Microbiology, University of Health Sciences, Van Training and Research Hospital, Van, Türkiye
⁴ Department of Medical Microbiology, Erzurum City Hospital, Erzurum, Türkiye
⁵ Department of Medical Microbiology, Samsun Training and Research Hospital, Samsun, Türkiye 
⁶ Department of Hyperbaric and Diving Medicine, University of Health Sciences, Gülhane Training and Research Hospital, Ankara, Türkiye

Corresponding author: Dr Recep Özkan, Department of Hyperbaric and Diving Medicine, Ataturk University, 25240 Erzurum, Türkiye
ORCiD: 0000-0001-7342-6473
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Keywords
Air; Bacteriology; Compressors; Contamination; Gas supply; Infection; Scuba diving

Abstract
(Özkan R, Turkmen O, Okumuş E, Özhan S, Sivrikaya H, Başbulut E, Ozgok Kangal K. Microbiological monitoring of scuba cylinders under routine filling and seasonal diving conditions. Diving and Hyperbaric Medicine. 2026;56(3):265−270. doi: 10.28920/dhm56.3.265-270. PMID: 42743565.)
Introduction: The aim of this study was to monitor the microbiological status of the inner surfaces of scuba cylinders under routine air filling conditions and to assess whether microbiological contamination emerges or persists over time.
Methods: A prospective longitudinal microbiological study was conducted using two complementary sampling models. Serial sampling of a steel scuba cylinder and its associated compressor air filter was performed at three-day intervals over 45 days. To assess reproducibility under operational conditions, additional microbiological sampling was performed from 27 scuba cylinders actively used during the diving season. Samples were analysed using standard culture methods.
Results: No microbial growth was detected in bacterial cultures obtained from any of the cylinder inner surface or compressor air filter samples throughout the 45-day monitoring period. No temporal changes or cumulative contamination trends were observed. Similarly, no microbial growth was detected in cultures obtained from the additional 27 scuba cylinders sampled during the active diving season.
Conclusions: Under routine operating conditions with standard maintenance and air filtration practices, the internal environment of scuba cylinders may remain microbiologically stable over time, suggesting a low risk of microbiological contamination in properly maintained compressed air systems.

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The effect of drysuit diving in warm water on body temperature and post immersion orthostatic hypotension

Joshua T Murphey¹, Hayden W Hess¹, Morgan L Worley¹, Glenda Anderson¹, Jacqueline Schwob¹, Brian A Monaco^1,2, David Hostler^1,2

¹ Center for Research and Education in Special Environments, Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, USA
² Department of Emergency Medicine, University at Buffalo, Buffalo, NY, USA

Corresponding author: Dr David Hostler, University at Buffalo, Exercise and Nutrition Sciences, 116 Sherman Hall, Buffalo NY 14020, USA
ORCiD: 0000-0002-7711-4001
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Keywords
Body temperature regulation; Cardiovascular physiology; Hyperthermia; Immersion; Orthostatic intolerance; Protective clothing

Abstract
(Murphey JT, Hess HW, Worley ML, Anderson G, Schwob J, Monaco BA, Hostler D. The effect of drysuit diving in warm water on body temperature and post immersion orthostatic hypotension. Diving and Hyperbaric Medicine. 2026 30 September;56(3):271−279. doi: 10.28920/dhm56.3.271-279. PMID: 42743566.)
Introduction: Warm-water diving can limit heat dissipation, particularly when performed in fully encapsulating protective gear, leading to substantial thermal and cardiovascular strain that may impair diver safety. Following immersion, removal of hydrostatic support combined with heat-induced vasodilation may reduce central blood volume and increase susceptibility to orthostatic intolerance during egress and recovery. The extent to which this thermal strain impairs post-immersion orthostatic tolerance remains unknown.
Methods: Four randomised, crossover immersion trials were conducted at 28°C, 33°C, 38°C without precooling (38°C), and 38°C with precooling (38°C + Cool), with subjects wearing fully encapsulating dive gear. Subjects walked for up to 60 minutes at approximately 50% of O₂max heart rate (HR) or until core temperature (Tc) reached 38.5°C, or they voluntarily stopped. Tc, HR, and perceptual measures were recorded every 10 minutes. Orthostatic tolerance was assessed after immersion via a 70° head-up tilt test.
Results: Eight healthy adults completed all aspects of the study. Tc and HR were higher during both 38°C conditions compared with 28°C and 33°C (all P < 0.01) with no differences between 38°C and 38°C + Cool. Sweat loss exceeded 1.2 (SD 0.67) L⋅h^-1 in both 38°C conditions compared with ≤ 0.3 (0.32) L⋅h^-1 at 28°C and 33°C (P < 0.01). Survival analysis showed orthostatic tolerance decreased with increasing thermal stress (log-rank P = 0.027; trend P = 0.003). Precooling did not reduce peak Tc or HR, nor did it improve tolerance time in 38°C water.
Conclusions: Encapsulated warm-water diving causes heat stress and cardiovascular strain that persists after immersion, impairing orthostatic tolerance. Precooling does not significantly reduce these outcomes.

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Maintained critical flicker fusion frequency after acute hyperbaric hyperoxia at 140 kPa

Jochen D Schipke¹, Thomas Muth², Anne-Kathrin Brebeck³, Dominik von Hertlein⁴, Fabian N Möller^5,6,7

¹ Research Group Experimental Surgery, University Hospital Düsseldorf, Düsseldorf, Germany
² Institute of Occupational, Social, Environmental Medicine, Faculty of Medicine, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
³ Artemis MVZ Frankfurt, Frankfurt/Main, Germany
⁴ German Sport University Cologne, Department of Psychology, Cologne, Germany
⁵ University of Oregon, Department of Human Physiology, Eugene, OR, USA
⁶ Massachusetts Institute of Technology, Cambridge, MA, USA
⁷ German Sport University Cologne, Department of Exercise Physiology, Cologne, Germany

Corresponding author: Professor Jochen Schipke, Research Group Experimental Surgery, University Hospital, Moorenstrasse 5, D-40545 Düsseldorf, Germany
ORCiD: 0000-0002-1747-5657
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Keywords
Central nervous system; Diving; HRV; Hyperbaric oxygen; Narcosis; Oxygen; Scuba diving

Abstract
(Schipke JD, Muth T, Brebeck A-K, von Hertlein D, Möller FN. Maintained critical flicker fusion frequency after acute hyperbaric hyperoxia at 140 kPa. Diving and Hyperbaric Medicine. 2026 30 September;56(3):280−285. doi: 10.28920/dhm56.3.280-285. PMID: 42743567.)
Introduction: In diving medicine, critical flicker fusion frequency (cFFF) has been employed to assess alertness under varying ambient pressures and gas compositions, yet the effects of elevated oxygen partial pressure on cFFF performance underwater remain inconsistently characterised. This investigation aimed to assess the impact of breathing 140 kPa oxygen on underwater cFFF performance, a pressure level corresponding to established safety limits and common closed-circuit rebreather setpoints during operational diving.
Methods: Nineteen experienced divers (10 females; mean age 23.8 [SD 3.0] years) completed cFFF assessments under three conditions: breathing air at poolside (21 kPa O₂), breathing air at 4 m depth (29 kPa O₂), and breathing 100% oxygen at 4 m depth (140 kPa O₂). Concurrent measurements included heart rate, respiratory rate, and heart rate variability indices representing autonomic function; specifically the LF/HF ratio indicating sympathetic activity and RMSSD reflecting parasympathetic activity.
Results: Mean cFFF breathing air at poolside was 37.9 (SD 2.9) Hz and breathing 100% oxygen at 4 m was 37.2 (SD 2.5) Hz, indicating that mild hyperoxia at 140 kPa does not impair cortical processing speed or visual temporal resolution. However, oxygen breathing produced notable cardiovascular and respiratory effects: heart rate decreased from 70.9 (10) to 67.8 (11.6) beats per minute, respiratory rate declined from 15.2 (2.7) to 13.4  (1.7) breaths per minute, the LF/HF ratio decreased from 5.9 (1.4) to 3.1 (2.0), and RMSSD increased from 73.7 (10.8) to 97.0 (6.6) milliseconds. These physiological changes indicate reduced sympathetic activity and enhanced parasympathetic tone during oxygen breathing.
Conclusions: The findings suggest that breathing 140 kPa oxygen during shallow water immersion maintains neural integrity as measured by cFFF while beneficially modulating autonomic regulation toward parasympathetic dominance. This autonomic shift resembles known effects of both submersion and moderate hyperoxia, supporting the safety profile of current oxygen exposure protocols in recreational and technical diving.

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Early nitrogen wash-out for inside attendants during hyperbaric oxygen therapy: a novel oxygen distribution regimen

Mårten Silvanius^1,2, Oscar Plogmark³, Måns Forsberg^1,2,4, Oskar Frånberg^1,3

¹ Department of Mathematics and Natural Sciences, Blekinge Institute of Technology, Karlskrona Sweden
² Swedish Armed Forces Diving and Naval Medicine Centre, Karlskrona Sweden
³ Department of Respiratory Medicine and Allergology, Institution for Clinical Sciences, Lund University, Lund, Sweden
⁴ Regional Hospital of Helsingborg, Helsingborg, Sweden

Corresponding author: Mårten Silvanius, Swedish Armed Forces, Karlskrona Sweden
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Keywords
Decompression sickness; Decompression tables; Hyperbaric oxygen treatment; Hyperbaric research; Pressure chambers

Abstract
Silvanius M, Plogmark O, Forsberg M, Frånberg O. Early nitrogen wash-out for inside attendants during hyperbaric oxygen therapy: a novel oxygen distribution regimen. Diving and Hyperbaric Medicine. 2026 30 September;56(3):286−293. doi: 10.28920/dhm56.3.286-293. PMID: 42743568.)
Introduction: Hyperbaric oxygen therapy (HBOT) is widely used as treatment of decompression sickness (DCS). The patient breathes oxygen at an elevated oxygen partial pressure of up to 280 kPa, whereas any inside attendant (IA) normally breathes air. This results in nitrogen uptake and tissue loading in the IA, which must be considered during decompression. The US Navy Treatment Table 6, and its equivalent used by the Swedish Armed Forces, prescribe periods of oxygen breathing prior to and during decompression to reduce the risk of DCS for the IA. However, since these oxygen periods are concentrated toward the latter part of the hyperbaric treatment, they do not account for the possibility of rapid decompression in the event of an earlier emergency.
Methods: We suggest rescheduling the distribution of oxygen for the IA to an earlier stage of the HBOT, which would allow early emergency decompression to a greater extent than the traditional IA oxygen regimen. To verify the duration of oxygen periods and their timing, we used the exponential linear Thalmann decompression algorithm with SWEN21B parameters to analyse compartmental gas load and perform a comparison between the original and our newly proposed regimens.
Results: We identified an alternative oxygen regimen for the inside attendant (IA) that remains within the permissible limits of the decompression algorithm yet allows for emergency decompression to be performed over an extended section of the period of compression.
Conclusions: Based on the decompression model used herein, we can conclude that greater flexibility in emergency decompression is possible if the oxygen regimen for the inside attendant (IA) is administered at an earlier stage of the therapy session.

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The effect of hyperoxic environment on lung function and myopisation in an extended closed-circuit rebreather diving expedition

Sofia A Sokolowski-Wojnicki^1,2, Mikolaj J Wojnicki³, Anne K Räisänen-Sokolowski^1,2,4

¹ Department of Pathology, University of Helsinki, Finland
² DAN Europe Research Division (Roseto-Helsinki), Helsinki, Finland
³ Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
⁴ Department of Pathology, Helsinki University Hospital, Helsinki, Finland

Corresponding author: Sofia A Sokolowski-Wojnicki, Department of Pathology, University of Helsinki, Finland
ORCiD: 0000-0002-7936-1436
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Keywords
Myopia; Oxygen toxicity; Scientific diving; Side effects; Spirometry; Technical diving; Vision

Abstract
(Sokolowski-Wojnicki SA, Wojnicki MJ, Räisänen-Sokolowski AK. The effect of hyperoxic environment on lung function and myopisation in an extended closed-circuit rebreather diving expedition. Diving and Hyperbaric Medicine. 2026 30 September;56(3):294−302. doi: 10.28920/dhm56.3.294-302. PMID: 42743569.)
Introduction: Repetitive closed-circuit rebreather (CCR) dives subject the human body to a hyperoxic environment. Prolonged oxygen exposure can lead to lung abnormalities and myopic shift. The aim of this study was to analyse the effects of a 31-day period of repeated CCR dives on divers’ lung function and visual acuity.
Methods: The CCR divers recruited for the study were participating in a research project in Chuuk Lagoon, Micronesia. Weekly measurements included lung function using spirometry and visual acuity with a Snellen chart. Oxygen exposure was calculated using multiple models. The impact on spirometry was tested by comparing the values before and after the expedition and by running regression analysis against accumulated oxygen exposure.
Results: The divers (n = 12) performed a total of 173 CCR dives with mean (SD) maximum depth of 38 (13.9) msw and dive time 101 (38.8) min. The daily oxygen exposure limits for unit pulmonary toxic dose and central nervous system toxicity were respected. One diver had a decrease in multiple lung function parameters. Another developed spirometric evidence of mild obstruction by the end of the expedition. However, there were no statistically significant changes in spirometry results. Visual acuity showed fluctuations throughout the expedition, but no overall trend.
Conclusions: Diving expeditions can be executed safely when respecting the guidelines for oxygen exposure. Reasonable oxygen exposure does not seem to significantly affect lung function or visual acuity.

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Scuba-related injuries presenting to United States emergency departments: paediatric and adult patterns

Andy Tom¹, Sam Lindberg¹, Sergio Navarro², Daniel Stephens²

¹ Mayo Clinic Alix School of Medicine, Mayo Clinic, Rochester, Minnesota, USA
² Division of Trauma, Critical Care, and General Surgery, Department of Surgery, Mayo Clinic, Rochester, Minnesota, USA

Corresponding author: Dr Daniel Stephens, Mayo Clinic Division of Trauma, Critical Care, and General Surgery, Mail Station: RONT02800-TR, 200 First Street SW, Rochester, MN, 55905, USA
ORCiD: 0000-0002-6980-0001
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Keywords
Arterial gas embolism; Barotrauma; Children; Decompression sickness; Drowning; Epidemiology; Pediatric divers

Abstract
(Tom A, Lindberg S, Navarro S, Stephens D. Scuba-related injuries presenting to United States emergency departments: paediatric and adult patterns. Diving and Hyperbaric Medicine. 2026 30 September;56(3):303−308. doi: 10.28920/dhm56.3.303-308. PMID: 42743570.)
Introduction: Scuba diving is a popular sport that carries risks unique to the underwater environment. Paediatric emergency department presentations for scuba diving injuries are incompletely characterised, particularly in comparison with adults.
Methods: We retrospectively analysed scuba-related injuries recorded in the National Electronic Injury Surveillance System (NEISS) from 2005–2024. We estimated national paediatric emergency department presentations using NEISS weights and compared injury categories and hospitalisation rates between paediatric and adult patients.
Results: We identified 68 paediatric cases, corresponding to an estimated 122 paediatric scuba-related emergency department presentations annually. Trauma was the most common injury category (41.2%), followed by otitis (17.6%) and ear, sinus, ocular, or dental barotrauma (16.2%). Hospitalisation was most common among patients with possible decompression sickness or arterial gas embolism (DCS/AGE) (42.9%) and drowning/aspiration (25.0%). Compared with adults, paediatric patients were less often hospitalised (10.3% vs 21.4%, P = 0.038), more likely to present with traumatic injuries (41.2% vs 26.1%, P = 0.010), and less likely to present with possible DCS/AGE (10.3% vs 25.0%, P = 0.006).
Conclusions: Among patients presenting to United States emergency departments with scuba-related injuries, paediatric patients most commonly had trauma, otitis, or ear, sinus, ocular, or dental barotrauma. Paediatric divers were also less likely than adults to experience DCS/AGE injuries and were less likely than adults to require hospitalisation. Our data describes emergency department presentation patterns rather than overall injury risk among paediatric scuba divers.

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Prevalence of laryngopharyngeal reflux symptoms in divers

Bastien A Valencia-Sanchez¹, Natalie Weiss¹, Evelyn Echevarria Cruz², Raana Zakeri^3,4, Frauke Tillmans³, Amy Rutt¹

¹ Department of Otolaryngology – Head and Neck Surgery, Mayo Clinic Florida, Jacksonville, FL, USA.
² Nova Southestern University – Kiran C. Patel College of Osteopathic Medicine, Davie, FL, USA
³ Divers Alert Network, Durham, NC, USA
⁴ Department of Epidemiology, UNC Gillings School of Global Public Health, University of North Carolina at Chapel Hill, NC, USA

Corresponding author: Dr Amy Rutt, Department of Otolaryngology – Head & Neck Surgery, Mayo Clinic in Florida, 4500 San Pablo Rd, Jacksonville, FL 32224, USA
ORCiD: 0000-0002-7704-6328
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Keywords
DAN – Divers Alert Network; Diving medicine; ENT; Epidemiology; Health surveys; Recreational divers; Technical diving

Abstract
(Valencia-Sanchez BA, Weiss N, Echevarria Cruz E, Zakeri R, Tillmans F, Rutt A. Prevalence of laryngopharyngeal reflux symptoms in divers. Diving and Hyperbaric Medicine. 2026 30 September;56(3):309−316. doi: 10.28920/dhm56.3.309-316. PMID: 42743571.)
Introduction: Laryngopharyngeal symptoms (LPS) refer to aerodigestive complaints that may result from the retrograde flow of gastric contents into the upper aerodigestive tract. These symptoms may be under-recognised in populations exposed to mechanical or environmental stressors. Divers may be at increased risk due to factors such as pressure changes and body positioning. This study characterised the prevalence and severity of LPS among divers and identified associated risk factors.
Methods: A cross-sectional, anonymous survey was distributed to members of the Divers Alert Network (DAN). Collected data included demographics, diving-related behaviours, medical history, and LPS burden measured using the Reflux Symptom Index (RSI).
Results: Of the 309 survey responses analysed, 47.2% were male with a median age of 50.0 years (IQR: 40.0−60.0). Among 291 divers with complete RSI data, 26.1% (95% CI, 21.4–31.5%) had abnormal RSI scores, representing a +16.0 percentage-point increase (95% CI, 11.3%−21.4%) over non-diving population estimates (P < 0.001). In multivariable analysis, female sex (adjusted prevalence rate [aPR] 1.59, 95% CI 1.07–2.37) and gastroesophageal reflux disease (GERD) history (aPR 1.75, 95% CI 1.16–2.65) were independent predictors. Recreational divers had a lower risk (aPR 0.59, 95% CI 0.39–0.90). Approximately 5% of respondents described their symptoms as life-threatening.
Conclusions: Divers may represent an under-recognised population at elevated risk for LPS. Female sex and GERD history were associated with greater symptom burden, while recreational diving appeared less provocative compared to technical diving. These findings may have implications for risk stratification and symptom management in the diving community.

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Forensic analysis of an unwitnessed fatal diving accident using in-water investigative reconstruction

Veronika Rybárová¹, František Novomeský¹, Radek Prygl², Jiří Šejba²

¹ Department of Forensic Medicine and Medicolegal Expertise, Jessenius Faculty of Medicine, Comenius University in Bratislava, University Hospital, Martin, Slovak Republic
² Department of Special Diving Operations and Training, Police of the Czech Republic, Czech Republic

Corresponding author: Dr Veronika Rybárová, PhD, Department of Forensic Medicine and Medicolegal Expertise, Jessenius Faculty of Medicine, Comenius University in Bratislava, University Hospital, Kollárova 2, 036 01 Martin, Slovak Republic
ORCiD: 0000-0003-2619-3333
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Keywords
Accidents; Autopsy; Diving deaths; Forensic diving medicine; Re-enactment; Simulation; Underwater accident reconstruction

Abstract

(Rybárová V, Novomeský F, Prygl R, Šejba J. Forensic analysis of an unwitnessed fatal diving accident using in-water investigative reconstruction. Diving and Hyperbaric Medicine. 2026 30 September;56(3):317−322. doi: 10.28920/dhm56.3.317-322. PMID: 42743572.)
Unwitnessed diving fatalities present significant challenges for forensic investigation. We describe a fatal diving accident involving a 32-year-old experienced female diver during a deep night dive in freshwater. The diver became separated from her buddy and was recovered at depth in a head-down position, with evidence of entanglement of the central manifold valve of the twin-tank open-circuit breathing apparatus by a thin guideline. Autopsy findings were consistent with drowning. Technical examination of the diving equipment revealed no mechanical malfunction. Given the absence of eyewitnesses and inconclusive assessment of the accident circumstances, an underwater reconstruction was conducted in collaboration with a police diving unit. Using the original breathing apparatus and controlled underwater conditions, the reconstruction evaluated the technical feasibility of various accident scenarios, including entanglement, buoyancy redistribution, and loss of equipment control. The reconstruction demonstrated that unintentional formation of a simple guideline loop around the central manifold valve could occur during attempts at disentanglement. Partial inflation of the buoyancy control device and drysuit, combined with mechanical constraint of the breathing apparatus due to entanglement, resulted in inversion into a head-down position and displacement of the breathing apparatus following release of the waist strap. These configurations substantially impaired the diver’s self-rescue capability and were consistent with objective findings documented at recovery. This case underscores the forensic value of controlled underwater reconstruction as a complementary investigative tool in unwitnessed technical diving fatalities and highlights its potential contribution to accident analysis and prevention.

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

Evaluation of external ventricular drain performance under hyperbaric conditions: a bench study

Rahulkumar Ramchandani¹, Zhiliang C Lin^1,2, Bridget Devaney^1,2, Rosalind L Jeffree^3,4, Theo Tsouras¹

¹ Department of Intensive Care and Hyperbaric Medicine, The Alfred Care Group, Bayside Health, Melbourne, Australia
² School of Public Health and Preventative Medicine, Monash University, Melbourne, Australia
³ Neurosurgery Department, The Alfred Care Group, Bayside Health, Melbourne, Australia
⁴ Department of Surgery, Monash University, Clayton, Victoria, Australia

Corresponding author: Dr Bridget Devaney, Department of Intensive Care and Hyperbaric Medicine, The Alfred Care Group, Bayside Health, 55 Commercial Road, Melbourne, VIC 3004, Australia
ORCiD: 0000-0001-6521-418X
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Keywords
EVD; Hyperbaric chambers; Intensive care; Intracranial pressure; Neurosurgery

Abstract
(Ramchandani R, Lin ZC, Devaney B, Jeffree RL, Tsouras T. Evaluation of external ventricular drain performance under hyperbaric conditions: a bench study.  Diving and Hyperbaric Medicine. 2026 30 September;56(3):323−328. doi: 10.28920/dhm56.3.323-328. PMID: 42743573.)
Introduction: External ventricular drains (EVDs) are widely used for intracranial pressure (ICP) monitoring and cerebrospinal fluid (CSF) diversion in neurocritical care. Hyperbaric oxygen treatment (HBOT) exposes medical devices to increased ambient pressure; however, limited data exists regarding EVD performance and reliability under hyperbaric conditions.
Methods: A bench study was conducted to evaluate EVD performance under hyperbaric conditions. A rigid, non-compressible saline-filled column was used to assess pressure measurement stability independent of compliance effects. Additional compliance-based syringe models were explored to assess the feasibility of evaluating unclamped drainage behaviour. A commercially available EVD system (CODMAN EDS 3; Codman & Shurtleff, a Johnson & Johnson company, Raynham, MA, USA) was exposed to stepwise ambient pressures from 101 to 283 kPa (1.0–2.8 atmospheres absolute) in a multiplace hyperbaric chamber. Pressure measurements, drainage behaviour, fluid column stability, and system integrity were assessed.
Results: The CODMAN EDS 3 EVD system maintained structural integrity across tested pressure levels. While pressure measurements were stable in the rigid open glass syringe model, the closed compliance-based models demonstrated pressure variability during chamber pressurisation, including when closed to fluid drainage. Unclamped testing using these models demonstrated inconsistent fluid dynamics, precluding reliable assessment of fluid drainage behaviour under hyperbaric conditions.
Conclusions: The CODMAN EDS 3 EVD system remained structurally intact during hyperbaric exposure; however, pressure measurements varied in closed models, including when closed to fluid drainage. ICP measurements obtained during HBOT should be interpreted with caution due to potential pressure-related artefacts. Reliable continuous assessment of fluid pressure drainage behaviour remains limited by current bench model constraints. Further research incorporating advanced brain compliance simulation models and carefully designed in-vivo observational studies is required to better characterise EVD behaviour under hyperbaric conditions and to ensure safe clinical use and accurate interpretation of ICP measurements in the hyperbaric environment.

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Diving-related ear, nose, and throat disorders: a structured review using a phase-of-dive framework

Anna Onderkova¹

¹ Royal Brompton Hospital, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom

Corresponding author: Dr Anna Onderkova, Royal Brompton Hospital, Guy’s and St Thomas’ NHS Foundation Trust, Sydney St, London SW3 6NP, United Kingdom
ORCiD: 0000-0002-4383-3040
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Keywords
Barotrauma; Decompression illness; Inner ear; Operations – diving; Profile; Valsalva manoeuvre; Vertigo

Abstract
(Onderkova A. Diving-related ear, nose, and throat disorders: a structured review using a phase-of-dive framework. Diving and Hyperbaric Medicine. 2026 30 September;56(3):329−341. doi: 10.28920/dhm56.3.329-341. PMID: 42743574.)
Introduction: The aim of this review was to synthesise evidence on ear, nose, and throat (ENT) and related head and neck complications in scuba divers, with emphasis on mechanisms of injury, dive phase-specific risk patterns, and implications for clinical management and fitness-to-dive decision-making.
Methods: A structured literature search of PubMed, Embase (Ovid), and the Cochrane Library identified systematic reviews, clinical trials, cohort studies, and case series reporting clinically relevant ENT outcomes in scuba divers. Animal studies, freediving studies, and papers focused solely on non-ENT complications were excluded. Forty analytic studies met inclusion criteria, including large cross-sectional surveys and multiple case series of inner ear decompression sickness. Study characteristics and levels of evidence were summarised, and findings were integrated into a phase-of-dive framework (descent, bottom time, ascent).
Results: Across included studies, middle-ear barotrauma was the most prevalent diving-related ENT injury, particularly during descent. Inner ear barotrauma and inner ear decompression sickness were less common but carried a substantially higher risk of persistent auditory or vestibular deficit. Additional reported conditions included sinus barotrauma, otitis externa and external auditory canal exostoses, temporomandibular joint symptoms, odontobarotrauma, and marine-exposure injuries. Evidence concerning postoperative states, following operations such as stapedectomy, tympanoplasty, mastoidectomy, and cochlear implantation, was limited, heterogeneous, and often contradictory, with few data to guide return-to-dive clearance.
Conclusion: Scuba diving-related ENT complications appear to be diverse, influenced by dive phase, and shaped by individual anatomical and physiological factors. A phase-aware framework offers clinicians a useful way to contextualise symptom onset and guide prevention and counselling, particularly for divers with prior ear or nasal surgery or implanted devices. Prospective studies are needed to refine screening practices and establish evidence-based return-to-dive recommendations.

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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.

Mental health and neurodevelopmental factors relevant to recreational fitness-to-dive assessment: a structured review and clinical considerations

Calina Ouliaris¹, Bram Querido², Thijs T Wingelaar^3,4, Neil D Banham⁵

¹ Spring Hill, Brisbane, Australia
² Praktijk Querido, Hilversum, the Netherlands
³ Dutch Society of Diving and Hyperbaric Medicine, Bilthoven, the Netherlands
⁴ Royal Netherlands Navy, Diving Medical Center, Den Helder, the Netherlands
⁵ Department of Hyperbaric Medicine, Fiona Stanley Hospital, Murdoch WA, Australia

Corresponding author: Dr Neil Banham Department of Hyperbaric Medicine, Fiona Stanley Hospital, 11 Robin Warren Drive, Murdoch WA 6150, Australia
ORCiD: 0000-0002-1737-5859
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Keywords
Medicals – diving; Panic; Psychiatry; Psychotropic drugs; Risk assessment; Scuba diving; Stress

Abstract
(Ouliaris C, Querido B, Wingelaar TT, Banham ND. Mental health and neurodevelopmental factors relevant to recreational fitness-to-dive assessment: a structured review and clinical considerations. Diving and Hyperbaric Medicine. 2026 30 September;56(3):342−349. doi: 10.28920/dhm56.3.342-349. PMID: 42743575.)
Introduction: Mental health and neurodevelopmental factors, including psychiatric disorders and psychotropic medication use, are commonly identified during recreational diving medical screening. However, guidance for fitness-to-dive assessment in this context remains limited and often relies on diagnostic categories and theoretical risk, contributing to variability in clinical decision-making.
Methods: A structured review of the literature was conducted to identify evidence relevant to fitness-to-dive assessment where mental health and neurodevelopmental factors may be relevant. Searches of PubMed were supplemented by manual review of key references. Studies addressing cognitive function, behaviour, psychiatric stability, medication and substance effects and environmental influences in recreational diving were included and synthesised thematically.
Results: Twenty-nine studies were included. The evidence base was heterogeneous and comprised primarily observational studies, experimental research on cognitive performance under diving conditions and a smaller number of reviews and guidance-oriented publications. Across the literature, functional capacity, behavioural responses under stress and psychiatric stability emerged as central determinants of diving safety. Cognitive performance is reduced under diving conditions, suggesting limited cognitive reserve and increased vulnerability to impairment. Panic and maladaptive behavioural responses represent key pathways to adverse outcomes. Medication use alone is not a consistent predictor of risk, although side effects and periods of clinical instability are relevant. Environmental factors inherent to diving may further amplify underlying vulnerabilities.
Conclusions: Fitness-to-dive assessment in the context of mental health and neurodevelopmental factors cannot be determined by diagnosis alone. The available evidence supports a multidimensional, context-dependent approach incorporating functional capacity, behavioural reliability, psychiatric stability, medication effects and environmental demands. Assessment should be individualised and grounded in clinical judgement, recognising that risk is probabilistic rather than binary. These findings may support more consistent and clinically relevant decision-making in recreational diving.

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Ultrasound protocols used to detect vascular gas emboli in divers: a systematic review

Benjamin L Turner¹, Thijs T Wingelaar^1,2, Feiko JM de Jong^1,3, Pieter Jan AM van Ooij^1,3, Rigo Hoencamp^4,5,6

¹ Royal Netherlands Navy, Diving and Submarine Medical Centre, Den Helder, the Netherlands
² Royal Netherlands Air and Space Force, Center for Man in Aviation, Soesterberg, the Netherlands
³ Amsterdam UMC, Location AMC, Department of Respiratory Medicine, Amsterdam, the Netherlands
⁴ Alrijne Hospital, Department of Surgery, Leiderdorp, the Netherlands
⁵ Erasmus MC, University Medical Center Rotterdam, Trauma Research Unit, Rotterdam, the Netherlands
⁶ Ministry of Defense, Defense Healthcare Organization, Utrecht, the Netherlands

Corresponding author: Benjamin L Turner, Royal Netherlands Navy, Diving and Submarine Medical Centre, Den Helder, the Netherlands
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Keywords 
Air embolism; Doppler; Echocardiography; Radiological imaging; Systematic review; Ultrasound; Venous gas embolism

Abstract
(Turner BL, Wingelaar TT, de Jong FJM, van Ooij PJAM, Hoencamp R. Ultrasound protocols used to detect vascular gas emboli in divers: a systematic review. Diving and Hyperbaric Medicine. 2026 30 September;56(3):350−360. doi: 10.28920/dhm56.3.350-360. PMID: 42743576.)
Introduction: Venous gas emboli (VGE) detected via ultrasound can be used as a surrogate marker for decompression stress. While Doppler ultrasound is the historical gold standard, two-dimensional (2D) ultrasonography offers advantages for on-site monitoring, including a wider field of view and reduced dependence on noise-free environments. This systematic review evaluates 2D ultrasonography protocols used in decompression research since the 2015 International Meeting on Ultrasound for Diving Research, identifying methodological similarities, differences, and adherence to consensus recommendations.
Methods: A search of PubMed and Scopus identified studies using 2D ultrasound to detect VGE in divers. Inclusion criteria were: (1) use of 2D ultrasound, (2) detection of VGE or monitoring of decompression stress, (3) inclusion of a diver cohort, and (4) publication after 2015. Data extraction focused on VGE scoring systems, ultrasound hardware, measurement protocols, and operator experience. Risk of bias was assessed using ROBINS-I-V2, and compliance with the 2015 consensus recommendations was evaluated.
Results: Twenty studies were included. The Eftedal-Brubakk scale was most commonly used (n = 15), with cardiac ultrasound as the primary imaging modality; one study assessed a peripheral vessel. Common shortcomings included post-dive measurements lasting less than two hours, underreporting of operator experience and hardware specifications, limited individual-level data, and inappropriate use of parametric statistics for ordinal bubble grade data. No study fully complied with all consensus recommendations.
Conclusions: This review demonstrates that, although two-dimensional ultrasound is widely used for post-dive VGE assessment, methodological heterogeneity with multiple shortcomings remain. Furthermore, nearly all studies restricted imaging to the heart, thus leaving peripheral vessel assessment largely unexplored.

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Evaluating the FitMáx questionnaire for fitness-to-dive assessments in a military population

Pieter D Dijk¹, Paul Clarijs¹, Thijs T Wingelaar¹

¹ Royal Netherlands Navy Diving and Submarine Medical Center, Rijkszee en Marinehaven, Den Helder, the Netherlands

Corresponding author: Dr Thijs Wingelaar, Royal Netherlands Navy Diving and Submarine Medical Center, Rijkszee en Marinehaven, 1780 CA Den Helder, the Netherlands
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Keywords
Cardiorespiratory fitness; Divers; Self-reported fitness; Recompression personnel; O2max; O2peak

Abstract

(Dijk PD, Clarijs P, Wingelaar TT. Evaluating the FitMáx questionnaire for fitness-to-dive assessments in a military population. Diving and Hyperbaric Medicine. 2026 30 September;56(3):361−364. doi: 10.28920/dhm56.3.361-364. PMID: 42743577.)
This study evaluated the validity of the FitMáx questionnaire for estimating VO₂peak in 157 Dutch Navy divers and recompression personnel, a population characterised by high physical fitness and occupational demands. While self-reported questionnaires offer a logistically feasible alternative to resource-intensive direct testing, their accuracy in fitness-to-dive assessments remains unclear. Participants completed the FitMáx questionnaire prior to cycle ergometry with direct VO₂peak measurement. Results showed a moderate correlation (r = 0.631, P < 0.001) between mean estimated VO₂max (43.7, SD 5.34 mL·kg^-1·min^-1) and mean measured VO2peak (45.4, SD 6.52 mL·kg^-1·min^-1), with the questionnaire systematically underestimating fitness by 1.8 mL·kg^-1·min^-1, with a 95% confidence interval of agreement limit of ± 10.9 mL·kg^-1·min^-1, and a moderate intraclass correlation coefficient of 0.748 (P < 0.001). False-positive and false-negative rates were 8.9% and 10.8%, respectively, raising concerns about reliability for pass/fail decisions. Participants reported difficulties answering questions unrelated to their routine activities, potentially contributing to the observed variability. Given these limitations, including the homogeneous, highly fit sample and the inability to differentiate between subgroups, the Royal Netherlands Navy Diving Medical Center has not adopted the FitMáx for fitness-to-dive evaluations. While questionnaires may streamline large-scale assessments, direct exercise testing remains valuable for precise, individualised risk stratification in occupational diving.

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Adaptations to breath-hold diving: from traditional divers to elite athletes

Jochen D Schipke¹, Ulrich Limper^2,3, Kay Tetzlaff⁴

¹ Research Group Experimental Surgery, University Hospital Düsseldorf, Düsseldorf, Germany
² German Aerospace Center, Institute of Aerospace Medicine, Cologne, Germany
³ Department of Anaesthesiology and Critical Care Medicine, Cologne-Merheim Medical Center, Hospital of Witten/Herdecke University, Cologne, Germany
⁴ Department of Sports Medicine, Medical Clinic, University Hospital Tuebingen, Germany

Corresponding author: Professor Jochen Schipke, Research Group Experimental Surgery, University Hospital Düsseldorf, Moorenstrasse 5, D-40545 Düsseldorf, Germany
ORCiD: 0000-0002-1747-5657
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Keywords
Adaptation; Breath-hold diving; Decompression sickness; History; Hypoxic blackout; Nitrogen; Repetitive diving; Taravana

Abstract

Schipke JD, Limper U, Tetzlaff K. Adaptations to breath-hold diving: from traditional divers to elite athletes. Diving and Hyperbaric Medicine. 2026 30 September;56(3):365−370. doi: 10.28920/dhm56.3.365-370. PMID: 42743578.)
Breath-hold diving exposes humans to repeated episodes of profound hypoxia and hypercapnia, eliciting physiological adaptations that enable prolonged underwater performance. This article summarises current knowledge on chronic adaptations in elite breath-hold athletes and traditional diving populations, including the Bajau sea nomads of Southeast Asia and the Korean Haenyeo divers. Evidence indicates that repeated apnoea induces adaptations across multiple physiological systems. Haematological changes include increased spleen size and enhanced splenic contraction, augmenting circulating haemoglobin and oxygen stores during apnoea. In elite divers, structured training can increase resting spleen volume, whereas the Bajau exhibit genetically associated splenic enlargement linked to variants near the PDE10A gene. Cardiopulmonary adaptations include modified pulmonary vascular responses to hypoxia, improved oxygen conservation, and metabolic shifts favoring efficient mitochondrial energy production. Molecular adaptations involve enhanced antioxidant defenses and activation of hypoxia-responsive pathways that may mitigate oxidative stress associated with repeated hypoxia-reoxygenation cycles. Emerging evidence also suggests neural plasticity and possible structural brain adaptations, although the long-term neurological consequences of chronic intermittent hypoxia exposure remain uncertain. Studies of traditional diving populations indicate that both phenotypic plasticity and genetic selection contribute to diving capacity, highlighting interactions between training and evolution. Despite these benefits, breath-hold diving also carries risks, including hypoxic blackout, decompression sickness, and potential neurological injury. Understanding the mechanisms underlying human tolerance to extreme hypoxia may have implications beyond diving physiology, including applications in cardiovascular medicine, hypoxic diseases, and rehabilitation. Further longitudinal, genomic, and mechanistic studies are needed to clarify the limits, benefits, and clinical relevance of these adaptations.

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Bilateral sudden sensorineural hearing loss following indirect lightning exposure successfully treated with hyperbaric oxygen therapy: a case report

Recep Özkan¹, Osman Türkmen², Kübra Yapici³, Zülküf Kaya³

¹ Department of Hyperbaric and Diving Medicine, Ataturk University Erzurum, Türkiye
² Department of Hyperbaric and Diving Medicine, Samsun Training and Research Hospital, Samsun, Türkiye 
³ Department of Otorhinolaryngology, Atatürk University Faculty of Medicine, Erzurum, Türkiye

Corresponding author: Dr Recep Özkan, Department of Hyperbaric and Diving Medicine, Ataturk University, 25240 Erzurum, Türkiye
ORCiD: 0000-0001-7342-6473
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Keywords
Audiometry; Cochlear injury; Deafness; Lightning injury

Abstract
(Özkan R, Türkmen O, Yapici K, Kaya Z. Bilateral sudden sensorineural hearing loss following indirect lightning exposure successfully treated with hyperbaric oxygen therapy: a case report. Diving and Hyperbaric Medicine. 2026 30 September;56(3):371−375. doi: 10.28920/dhm56.3.371-375. PMID: 42743579.)
Introduction: Lightning injuries may result in a wide spectrum of neurological and otological complications. Sudden sensorineural hearing loss (SSNHL) following indirect lightning exposure is rare, and evidence regarding the role of hyperbaric oxygen therapy (HBOT) remains limited. We report a case of severe bilateral SSNHL following indirect lightning exposure with substantial recovery after HBOT.
Case report: A 26-year-old man developed sudden bilateral hearing loss after a lightning strike hit a lightning rod approximately 20 m from his location. He experienced transient syncope and limb weakness consistent with keraunoparalysis. Audiometry demonstrated severe bilateral sensorineural hearing loss, with pure-tone averages (PTA) of 70 dB HL in the right ear and 75 dB HL in the left ear. Because of persistent hearing loss despite systemic corticosteroid treatment, HBOT was initiated approximately 105 days after injury. A total of 30 HBOT sessions were administered together with intratympanic steroid injections. After 20 sessions, PTAs improved to 39 dB HL and 42 dB HL. Following completion of treatment, PTAs improved to 15 dB HL and 12 dB HL, with speech discrimination scores of 96% bilaterally.
Conclusions: Severe bilateral SSNHL following indirect lightning exposure is rarely reported. Proposed mechanisms include cochlear injury, microvascular compromise, and oxidative damage to inner-ear structures. This case demonstrates that indirect lightning exposure may result in both keraunoparalysis and severe bilateral SSNHL. Substantial hearing recovery was observed despite initiation of HBOT more than three months after injury, suggesting a potential role for HBOT as part of a multidisciplinary treatment approach in selected cases.

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A case of severe multi-system decompression sickness requiring critical care, aggressive fluid resuscitation and hyperbaric oxygen therapy

Alice Palmer^1,2, Craig Holdstock^1,2, Doug Watts³, Rosanna J Stokes³, Jack Whiteley²

¹ Derriford Hospital, Plymouth, United Kingdom
² University Hospitals Plymouth NHS Trust, United Kingdom
³ DDRC Healthcare, Plymouth, United Kingdom

Corresponding author: Dr Alice Palmer, Derriford Hospital, Plymouth, United Kingdom
ORCiD: 0009-0008-1483-3384
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Keywords
Case reports; Diving medicine; Intensive care medicine; Recompression; Treatment; Venous gas embolism

Abstract

(Palmer A, Holdstock C, Watts D, Stokes RJ, Whiteley J. A case of severe multi-system decompression sickness requiring critical care, aggressive fluid resuscitation and hyperbaric oxygen therapy. Diving and Hyperbaric Medicine. 2026 30 September;56(3):376−380. doi: 10.28920/dhm56.3.376-380. PMID: 42743580.)
An experienced recreational diver developed a severe multisystem life-threatening decompression sickness following a series of eight dives over four days, the profiles of which were all within acceptable limits. The diver had marked haemoconcentration and required large volume intravenous fluid replacement during initial treatment. Similar presentations have previously only been described following deep dives, fast ascents or where mandatory decompression had been missed. The management of this case, including the involvement of a hyperbaric unit co-located to an intensive care department, and the underlying pathophysiology are discussed.

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.

Decompression sickness or ciguatera intoxication: a case report

Robert A van Hulst¹

¹ Departments of Hyperbaric Medicine and Anesthesiology, Academic Medical Centre, University of Amsterdam, The Netherlands

Corresponding author: Professor Robert van Hulst, Departments of Hyperbaric Medicine and Anesthesiology, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1100 DD, Amsterdam, the Netherlands
ORCiD: 0009-0002-6945-5508
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Keywords
Decompression sickness; Ecology; Fish; Intoxication; Neurology

Abstract

(van Hulst RA. Decompression sickness or ciguatera intoxication: a case report. Diving and Hyperbaric Medicine. 2026 30 September;56(3):381−383. doi: 10.28920/dhm56.3.381-383. PMID: 42743581.)
This report presents the case of a diver who suffered from ciguatera intoxication (CTX). After three days of consecutive diving, he arrived at hospital with symptoms of chest pain, shortness of breath, nausea, and had sensory abnormalities across his body, arms and legs. Although his clinical signs and symptoms may have suggested cardiac involvement or decompression sickness (DCS), ultimately his condition was caused by CTX after eating fish. This case illustrates the similarities between DCS and food intoxication. The common pathology of CTX is described and its differential diagnosis with DCS is discussed.

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.

In-water recompression for severe decompression illness in competitive freediving: a case report

Jake Johnston¹, Juan Valdivia^2,3, Leigh Baker⁴, Kelly Heape^1,5

¹ Department of Anesthesiology, Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
² Department of Neurosurgery, St. Joseph’s Hospital, Tampa, FL, USA
³ International Association for Development of Apnea (AIDA International), Medical and Science Committee, Zurich, Switzerland
⁴ Virginia Mason Franciscan Health, Seattle, WA, USA
⁵ Department of Anesthesiology and Perioperative Medicine, Royal Columbian Hospital, New Westminster, BC, Canada

Corresponding author: Dr Jake Johnston, Department of Anesthesiology, Pharmacology and Therapeutics, University of British Columbia, Room 11228, 11th Floor, 2775 Laurel Street, Vancouver, BC, Canada V5Z 1M9
ORCiD: 0000-0003-3847-9216
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Arterial gas embolism; Breath-hold diving; Decompression sickness; Diving medicine; Hyperbaric oxygen; Remote locations; Risk assessment

Abstract
(Johnston J, Valdivia J, Baker L, Heape K. In-water recompression for severe decompression illness in competitive freediving: a case report. Diving and Hyperbaric Medicine. 2026 30 September;56(3):384−387. doi: 10.28920/dhm56.3.384-387. PMID: 42743582.)
Introduction: Decompression illness (DCI) is a recognised risk of freediving. When timely hyperbaric oxygen therapy (HBOT) is unavailable, oxygen-based in-water recompression (IWR) may be considered.
Case report: A 49-year-old competitive freediver developed severe neurological DCI within minutes of surfacing from a dive to 117 metres of seawater at a sanctioned competition, with altered mental status, right facial droop, right hemiparesis and aphasia. With an anticipated 24–48 h delay to HBOT, emergency IWR was initiated with a full-face mask and 100% oxygen. Incremental ascent from 18 msw over 14.5 min produced substantial recovery. Residual gait instability and pronator drift prompted a second oxygen-IWR 5.5 h later from 15 msw over 41 min, achieving complete resolution.
Discussion: While this case had an excellent outcome, IWR carries significant risks including oxygen toxicity and drowning, and review identified serious safety and ethical failures. Patient selection is key; perceived benefit must be weighed carefully against risk.
Conclusions: IWR may be considered for DCI when HBOT is not promptly accessible. No IWR guidelines exist specifically for freedivers. The success of this case does not establish that deeper exposures were necessary or superior to shallower protocols. IWR is high-risk, requiring proper selection, trained personnel and favorable conditions.

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.

Measuring whole-body inert gas uptake and washout during submersion

Oscar Plogmark, Kristian Soltesz, Carl Hjelte, Oskar Frånberg

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.

An error was identified in Figure 3 of the published article. The images in the figure were incorrectly placed, resulting in the same image being shown for each part of the figure.

The online version of the article has been corrected, and the corrected figure will also be included in the version deposited in PubMed Central. However, three versions of the article had already been distributed before the error was identified and cannot be corrected retrospectively.

The error is limited to Figure 3 and does not affect the text, data, results or conclusions of the article.

The journal apologises for the error.

doi: 10.28920/dhm56.3.388.
PMID: 42743583.

Nicky Telles 
Editorial Manager