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06 December 2022

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Category: Information

06 December 2022

9801

2023 December;53(4) 

Diving Hyperb Med. 2023 December 20;53(4):299−305. doi: 10.28920/dhm53.4.299-305. PMID: 38091588. PMCID: PMC10944666.

Risk assessment of SWEN21 a suggested new dive table for the Swedish armed forces: bubble grades by ultrasonography

Carl Hjelte^1,2,3, Oskar Plogmark^1,2, Mårten Silvanius^2,4, Magnus Ekström¹, Oskar Frånberg^1,4

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 Sahlgrenska University Hospital, Anesthesia and Intensive Care, Gothenburg, Sweden
⁴ Blekinge Institute of Technology, Department of Mathematics and Natural Science, Karlskrona, Sweden

Corresponding author: Dr Carl Hjelte, Kungsladugårdsgatan 113B. 414 76, Gothenburg, Sweden
ORCiD: 0009-0009-5522-8735
carl_hjelte@hotmail

Keywords
Decompression; Decompression illness; Decompression tables; Diving; Echocardiography; Risk; Venous gas emboli

Abstract
(Hjelte C, Plogmark O, Silvanius M, Ekström M, Frånberg O. Risk assessment of SWEN21 a suggested new dive table for the Swedish armed forces: bubble grades by ultrasonography. Diving and Hyperbaric Medicine. 2023 December 20;53(4):299−305. doi: 10.28920/dhm53.4.299-305. PMID: 38091588. PMCID: PMC10944666.)
Introduction: To develop the diving capacity in the Swedish armed forces the current air decompression tables are under revision. A new decompression table named SWEN21 has been created to have a projected risk level of 1% for decompression sickness (DCS) at the no stop limits. The aim of this study was to evaluate the safety of SWEN21 through the measurement of venous gas emboli (VGE) in a dive series.
Methods: A total 154 dives were conducted by 47 divers in a hyperbaric wet chamber. As a proxy for DCS risk serial VGE measurements by echocardiography were conducted and graded according to the Eftedal-Brubakk scale. Measurements were done every 15 minutes for approximately 2 hours after each dive. Peak VGE grades for the different dive profiles were used in a Bayesian approach correlating VGE grade and risk of DCS. Symptoms of DCS were continually monitored.
Results: The median (interquartile range) peak VGE grade after limb flexion for a majority of the time-depth combinations, and of SWEN21 as a whole, was 3 (3–4) with the exception of two decompression profiles which resulted in a grade of 3.5 (3–4) and 4 (4–4) respectively. The estimated risk of DCS in the Bayesian model varied between 4.7–11.1%. Three dives (2%) resulted in DCS. All symptoms resolved with hyperbaric oxygen treatment.
Conclusions: This evaluation of the SWEN21 decompression table, using bubble formation measured with echocardiography, suggests that the risk of DCS may be higher than the projected 1%.

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.

Publication Type: Original article

Diving Hyperb Med. 2023 December 20;53(4):306−312. doi: 10.28920/dhm53.4.306-312. PMID: 38091589. PMCID: PMC10944662.

Rapture of the deep: gas narcosis may impair decision-making in scuba divers

Pauliina A Ahti¹, Jan Wikgren¹

¹ Centre for Interdisciplinary Brain Research, Department of Psychology, University of Jyväskylä, Finland

Corresponding author: Dr Pauliina A Ahti, Centre for Interdisciplinary Brain Research, Department of Psychology,
University of Jyväskylä, Finland
ORCiD: 000-002-6216-9616
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Cold; Deep diving; Gases; Nitrogen narcosis; Personality; Psychology; Scientific diving

Abstract
(Ahti PA, Wikgren J. Rapture of the deep: gas narcosis may impair decision-making in scuba divers. Diving and Hyperbaric Medicine. 2023 December 20;53(4):306−312. doi: 10.28920/dhm53.4.306-312. PMID: 38091589. PMCID: PMC10944662.)
Introduction: While gas narcosis is familiar to most divers conducting deep (> 30 metres) dives, its effects are often considered minuscule or subtle at 30 metres. However, previous studies have shown that narcosis may affect divers at depths usually considered safe from its influence, but little knowledge exists on the effects of gas narcosis on higher cognitive functions such as decision-making in relatively shallow water at 30 metres. Impaired decision-making could be a significant safety issue for a multitasking diver.
Methods: We conducted a study exploring the effects of gas narcosis on decision-making in divers breathing compressed air underwater. The divers (n = 22) were evenly divided into 5-metre and 30-metre groups. In the water, we used underwater tablets equipped with the Iowa Gambling Task (IGT), a well-known psychological task used to evaluate impairment in decision-making.
Results: The divers at 30 metres achieved a lower score (mean 1,584.5, standard deviation 436.7) in the IGT than the divers at 5 metres (mean 2,062.5, standard deviation 584.1). Age, body mass index, gender, or the number of previous dives did not affect performance in the IGT.
Conclusions: Our results suggest that gas narcosis may affect decision-making in scuba divers at 30 metres depth. This supports previous studies showing that gas narcosis is present at relatively shallow depths and shows that it may affect higher cognitive functions.

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.

Publication Type: Original article

Diving Hyperb Med. 2023 December 20;53(4):313−320. doi: 10.28920/dhm53.4.313-320. PMID: 38091590. PMCID: PMC10735670.

Full-face snorkel masks increase the incidence of hypoxaemia and hypercapnia during simulated snorkelling compared to conventional snorkels

Janneke Grundemann¹, Xavier CE Vrijdag¹, Nicole YE Wong², Nicholas Gant³, Simon J Mitchell^1,2,4, Hanna van Waart¹

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

Corresponding author: Dr Hanna van Waart, Department of Anaesthesiology, School of Medicine, University of Auckland,
Private Bag 92019, Auckland 1142, New Zealand
ORCiD: 0000-0002-6931-0168
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Diving research; Equipment; Hypercapnia; Hypoxia; Safety

Abstract
(Grundemann J, Vrijdag XCE, Wong NYE, Gant N, Mitchell SJ, van Waart H. Full-face snorkel masks increase the incidence of hypoxaemia and hypercapnia during simulated snorkelling compared to conventional snorkels. Diving and Hyperbaric Medicine. 2023 December 20;53(4):313−320. doi: 10.28920/dhm53.4.313-320. PMID: 38091590. PMCID: PMC10735670.)
Introduction: Air flow in full-face snorkel masks (FFSMs) should be unidirectional to prevent rebreathing of exhaled air. This study evaluated rebreathing and its consequences when using full-face snorkel masks compared to a conventional snorkel.
Methods: In a dry environment 20 participants wore three types of snorkel equipment in random order: Subea Easybreath FFSM; QingSong 180-degree panoramic FFSM; and a Beuchat Spy conventional snorkel (with nose clip), in three conditions: rest in a chair; light; and moderate intensity exercise on a cycle ergometer. Peripheral oxygen saturation, partial pressure of carbon dioxide (PCO₂) and oxygen (PO₂) in the end tidal gas and FFSM eye-pockets, respiratory rate, minute ventilation, were measured continuously. Experiments were discontinued if oxygen saturation dropped below 85%, or if end-tidal CO₂ exceeded 7.0 kPa.
Results: Experimental runs with the FFSMs had to be discontinued more often after exceeding 7.0 kPa end-tidal CO₂ compared to a conventional snorkel e.g., 18/40 (45%) versus 4/20 (20%) during light intensity exercise, and 9/22 (41%) versus 3/16 (19%) during moderate intensity exercise. Thirteen participants exhibited peripheral oxygen saturations below 95% (nine using FFSMs and four using the conventional snorkel) and five fell below 90% (four using FFSMs and one using the conventional snorkel). The PCO₂ and PO₂ in the eye-pockets of the FFSMs fluctuated and were significantly higher and
lower respectively than in inspired gas, which indicated rebreathing in all FFSM wearers.
Conclusions: Use of FFSMs may result in rebreathing due to non-unidirectional flow, leading to hypercapnia and hypoxaemia.

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.

Publication Type: Original article

Full article available here.

Diving Hyperb Med. 2023 December 20;53(4):321−326. doi: 10.28920/dhm53.4.321-326. PMID: 38091591. PMCID: PMC10944667.

Measuring whole body inert gas wash-out

Oscar Plogmark^1,2, Mårten Silvanius³, Max Olsson¹, Carl Hjelte^1,2, Magnus Ekström¹, Oskar Frånberg^1,3

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 Blekinge Institute of Technology, Department of Mathematics and Natural Science, Karlskrona, Sweden

Corresponding author: 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, Silvanius M, Olsson M, Hjelte C, Ekström M, Frånberg O. Measuring whole body inert gas wash-out. Diving and Hyperbaric Medicine. 2023 December 20;53(4):321−326. doi: 10.28920/dhm53.4.321-326. PMID: 38091591. PMCID: PMC10944667.)
Introduction: Quantifying inert gas wash-out is crucial to understanding the pathophysiology of decompression sickness. In this study, we developed a portable closed-circuit device for measuring inert gas wash-out and validated its precision and accuracy both with and without human subjects.
Methods: We developed an exhalate monitor with sensors for volume, temperature, water vapor and oxygen. Inert gas volume was extrapolated from these inputs using the ideal gas law. The device’s ability to detect volume differences while connected to a breathing machine was analysed by injecting a given gas volume eight times. One hundred and seventy-two coupled before-and-after measurements were then compared with a paired t-test. Drift in measured inert gas volume during unlabored breathing was evaluated in three subjects at rest using multilevel linear regression. A quasi-experimental crossover study with the same subjects was conducted to evaluate the device’s ability to detect inert gas changes in relation to diving interventions and simulate power.
Results: The difference between the injected volume (1,996 ml) and the device’s measured volume (1,986 ml) was -10 ml. The 95% confidence interval (CI) for the measured volume was 1,969 to 2,003 ml. Mean drift during a 43 min period of unlaboured breathing was -19 ml, (95% CI, -37 to -1). Our power simulation, based on a cross-over study design, determined a sample size of two subjects to detect a true mean difference of total inert gas wash-out volume of 100 ml.
Conclusions: We present a portable device with acceptable precision and accuracy to measure inert gas wash-out differences that may be physiologically relevant in the pathophysiology of decompression sickness.

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.

Publication Type: Original article

Diving Hyperb Med. 2023 December 20;53(4):327−332. doi: 10.28920/dhm53.4.327-332. PMID: 38091592. PMCID: PMC10735710.

Comparing the EMMA capnograph with sidestream capnography and arterial carbon dioxide pressure at 284 kPa

Xavier CE Vrijdag¹, Hanna van Waart¹, Chris Sames², Jamie W Sleigh^1,3, Simon J Mitchell^1,2,4

¹ Department of Anaesthesiology, University of Auckland, Auckland, New Zealand
² Slark Hyperbaric Unit, Waitemata District Health Board, Auckland, New Zealand
³ Department of Anaesthesia, Waikato Hospital, Hamilton, New Zealand
⁴ Department of Anaesthesia, Auckland City Hospital, Auckland, New Zealand

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

Keywords
Capnography; Hyperbaric chamber; Intensive care; Patient monitoring

Abstract
(Vrijdag XCE, van Waart H, Sames C, Sleigh JW, Mitchell SJ. Comparing the EMMA capnograph with sidestream capnography and arterial carbon dioxide pressure at 284 kPa. Diving and Hyperbaric Medicine. 2023 December 20;53(4):327−332. doi: 10.28920/dhm53.4.327-332. PMID: 38091592. PMCID: PMC10735710.)
Introduction: Capnography aids assessment of the adequacy of mechanical patient ventilation. Physical and physiological changes in hyperbaric environments create ventilation challenges which make end-tidal carbon dioxide (ETCO₂) measurement particularly important. However, obtaining accurate capnography in hyperbaric environments is widely considered difficult. This study investigated the EMMA capnograph for hyperbaric use.
Methods: We compared the EMMA capnograph to sidestream capnography and the gold standard arterial carbon dioxide blood gas analysis in a hyperbaric chamber. In 12 resting subjects breathing air at 284 kPa, we recorded ETCO₂ readings simultaneously derived from the EMMA and sidestream capnographs during two series of five breaths (total 24 measurements). An arterial blood gas sample was also taken simultaneously in five participants.
Results: Across all measurements there was a difference of about 0.1 kPa between the EMMA and sidestream capnographs indicating a very slight over-estimation of ETCO₂ by the EMMA capnograph, but fundamentally good agreement between the two end-tidal measurement methods. Compared to arterial blood gas pressure the non-significant difference was about 0.3 and 0.4 kPa for the EMMA and sidestream capnographs respectively.
Conclusions: In this study, the EMMA capnograph performed equally to the sidestream capnograph when compared directly, and both capnography measures gave clinically acceptable estimates of arterial PCO₂.

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.

Publication Type: Original article

Full article available here.

Diving Hyperb Med. 2023 December 20;53(4):333−339. doi: 10.28920/dhm53.4.333-339. PMID: 38091593. PMCID: PMC10944664. 

Within-diver variability in venous gas emboli (VGE) following repeated dives

David J Doolette^1,2, F Gregory Murphy¹

¹ Navy Experimental Diving Unit, Panama City, Florida, USA
² Department of Anaesthesiology, University of Auckland, New Zealand

Corresponding author: Associate Professor David J Doolette, Navy Experimental Diving Unit, Panama City, Florida, USA
ORCiD: 0000-0001-9027-3536
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Bubbles; Decompression sickness; Diving; Echocardiography; Risk

Abstract
(Doolette DJ, Murphy FG. Within-diver variability in venous gas emboli (VGE) following repeated dives. Diving and Hyperbaric Medicine. 2023 December 20;53(4):333−339. doi: 10.28920/dhm53.4.333-339. PMID: 38091593. PMCID: PMC10944664.)
Introduction: Venous gas emboli (VGE) are widely used as a surrogate endpoint instead of decompression sickness (DCS) in studies of decompression procedures. Peak post-dive VGE grades vary widely following repeated identical dives but little is known about how much of the variability in VGE grades is proportioned between-diver and within-diver.
Methods: A retrospective analysis of 834 man-dives on six dive profiles with post-dive VGE measurements were conducted under controlled laboratory conditions. Among these data, 151 divers did repeated dives on the same profile on two to nine occasions separated by at least one week (total of 693 man-dives). Data were analysed for between- and within-diver variability in peak post-dive VGE grades using mixed-effect models with diver as the random variable and associated intraclass correlation coefficients.
Results: Most divers produced a wide range of VGE grades after repeated dives on the same profile. The intraclass correlation coefficient (repeatability) was 0.33 indicating that 33% of the variability in VGE grades is between-diver variability; correspondingly, 67% of variability in VGE grades is within-diver variability. DCS cases were associated with an individual diver’s highest VGE grades and not with their lower VGE grades.
Conclusions: These data demonstrate large within-diver variability in VGE grades following repeated dives on the same dive profile and suggest there is substantial within-diver variability in susceptibility to DCS. Post-dive VGE grades are not useful for evaluating decompression practice for individual divers.

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.

Publication Type: Original article

Diving Hyperb Med. 2023 December 20;53(4):340−344. doi: 10.28920/dhm53.4.340-344. PMID: 38091594. PMCID: PMC10944665.

Pulmonary oxygen toxicity breath markers after heliox diving to 81 metres

Feiko JM de Jong^1,2, Paul Brinkman³, Thijs T Wingelaar^1,2, Pieter-Jan AM van Ooij^1,3, Robert A van Hulst²

¹ Royal Netherlands Navy Diving and Submarine Medical Centre, 1780 CA, Den Helder, The Netherlands
² Department of Anesthesiology, Amsterdam University Medical Center, location AMC, 1100 DD, Amsterdam, The Netherlands
³ Department of Pulmonology, Amsterdam University Medical Center, location AMC, 1100 DD, Amsterdam, The Netherlands

Corresponding author: Feiko JM de Jong, Royal Netherlands Navy Diving and Submarine Medical Centre, Rijkszee-en, Marinehaven, Postbus 10.000, 1780 CA, Den Helder, The Netherlands
ORCiD: 0009-0008-9804-8307
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Diving research; Helium; Military diving; Unit pulmonary toxic dose; Volatile organic compounds

Abstract

(de Jong FJM, Brinkman P, Wingelaar TT, van Ooij PJAM, van Hulst RA. Pulmonary oxygen toxicity breath markers after heliox diving to 81 metres. Diving and Hyperbaric Medicine. 2023 December 20;53(4):340−344. doi: 10.28920/dhm53.4.340-344. PMID: 38091594. PMCID: PMC10944665.)
Pulmonary oxygen toxicity (POT), an adverse reaction to an elevated partial pressure of oxygen in the lungs, can develop as a result of prolonged hyperbaric hyperoxic conditions. Initially starting with tracheal discomfort, it results in pulmonary symptoms and ultimately lung fibrosis. Previous studies identified several volatile organic compounds (VOCs) in exhaled breath indicative of POT after various wet and dry hyperbaric hypoxic exposures, predominantly in laboratory settings. This study examined VOCs after exposures to 81 metres of seawater by three navy divers during operational heliox diving. Univariate testing did not yield significant results. However, targeted multivariate analysis of POT-associated VOCs identified significant (P = 0.004) changes of dodecane, tetradecane, octane, methylcyclohexane, and butyl acetate during the 4 h post-dive sampling period. No airway symptoms or discomfort were reported. This study demonstrates that breath sampling can be performed in the field, and VOCs indicative of oxygen toxicity are exhaled without clinical symptoms of POT, strengthening the belief that POT develops on a subclinical-to-symptomatic spectrum. However, this study was performed during an actual diving operation and therefore various confounders were introduced, which were excluded in previous laboratory studies. Future studies could focus on optimising sampling protocols for field use to ensure uniformity and reproducibility, and on establishing dose-response relationships.

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

Publication Type: Short communication

Diving Hyperb Med. 2023 December 20;53(4):345−350. doi: 10.28920/dhm53.4.345-350. PMID: 38091595. PMCID: PMC10944668. 

Cerebral arterial gas embolism (CAGE) during open water scuba certification training whilst practising a controlled emergency swimming ascent

Neil Banham¹, Elisabete da Silva¹, John Lippmann²

¹ Department of Hyperbaric Medicine, Fiona Stanley Hospital, Murdoch, Australia
² Australasian Diving Safety Foundation, Melbourne, Australia

Corresponding author: Dr Neil Banham, Department of Hyperbaric Medicine, Fiona Stanley Hospital, 11 Warren Drive,
Murdoch WA 6150, Australia
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Case reports; CESA; Diving accidents; Emergency ascent; Pneumomediastinum; Pneumothorax; Pulmonary barotrauma

Abstract

(Banham N, da Silva E, Lippmann J. Cerebral arterial gas embolism (CAGE) during open water scuba certification training whilst practising a controlled emergency swimming ascent. Diving and Hyperbaric Medicine. 2023 December 20;53(4):345−350. doi: 10.28920/dhm53.4.345-350. PMID: 38091595. PMCID: PMC10944668.)
We report the case of a 23-year-old male novice diver who sustained cerebral arterial gas embolism (CAGE) during his open water certification training whilst practising a free ascent as part of the course. He developed immediate but transient neurological symptoms that had resolved on arrival to hospital. Radiological imaging of his chest showed small bilateral pneumothoraces, pneumopericardium and pneumomediastinum. In view of this he was treated with high flow normobaric oxygen rather than recompression, because of the risk of development of tension pneumothorax upon chamber decompression. There was no relapse of his neurological symptoms with this regimen. The utility and safety of free ascent training for recreational divers is discussed, as is whether a pneumothorax should be vented prior to recompression, as well as return to diving following pulmonary barotrauma.

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.

Publication Type: Case report

Diving Hyperb Med. 2023 December 20;53(4):351−355. doi: 10.28920/dhm53.4.351-355. PMID: 38091596. PMCID: PMC10944663.

Hyperbaric oxygen treatment in delayed post-hypoxic encephalopathy following inhalation of liquefied petroleum gas: a case report

Kubra Canarslan Demir¹, Burak Turgut¹, Kubra Ozgok Kangal¹, Taylan Zaman¹, Kemal Şimşek¹

¹ Underwater and Hyperbaric Medicine, University of Health Sciences, Gulhane Training and Research Hospital, Ankara, Turkey

Corresponding author: Dr Kübra Canarslan Demir, SBÜ-Gülhane Eğitim ve Araştırma Hastanesi, Sualtı Hekimliği ve Hiperbarik Tıp Kliniği, Etlik/Ankara, Turkey
ORCiD: 0000-0001-6911-2375
This email address is being protected from spambots. You need JavaScript enabled to view it.

Keywords
Brain; Dementia; Hyperbaric medicine; Neurology; Toxicity

Abstract

(Canarslan Demir K, Turgut B, Ozgok Kangal K, Zaman T, Şimşek K. Hyperbaric oxygen treatment in delayed posthypoxic encephalopathy following inhalation of liquefied petroleum gas: a case report. Diving and Hyperbaric Medicine. 2023 December 20;53(4):351−355. doi: 10.28920/dhm53.4.351-355. PMID: 38091596. PMCID: PMC10944663.)
Delayed post-hypoxic encephalopathy can occur after an episode of anoxia or hypoxia. Symptoms include apathy, confusion, and neurological deficits. We describe a 47-year-old male patient who inhaled gas from a kitchen stove liquid petroleum gas cylinder. He was diagnosed with hypoxic ischaemic encephalopathy 12 hours after his emergency department admission. He received six sessions of hyperbaric oxygen treatment (HBOT) and was discharged in a healthy state after six days. Fifteen days later, he experienced weakness, loss of appetite, forgetfulness, depression, balance problems, and inability to perform self-care. One week later, he developed urinary and fecal incontinence and was diagnosed with post-hypoxic encephalopathy. After 45 days from the onset of symptoms, he was referred to the Underwater and Hyperbaric Medicine Department for HBOT. The patient exhibited poor self-care and slow speech rate, as well as ataxic gait and dysdiadochokinesia. Hyperbaric oxygen was administered for twenty-four sessions, which significantly improved the patient’s neurological status with only hypoesthesia in the left hand remaining at the end of treatment. Hyperbaric oxygen has been reported as successful in treating some cases of delayed neurological sequelae following CO intoxication. It is possible that HBO therapy may also
be effective in delayed post-hypoxic encephalopathy from other causes. This may be achieved through mechanisms such as transfer of functional mitochondria to the injury site, remyelination of damaged neurons, angiogenesis and neurogenesis, production of anti-inflammatory cytokines, and balancing of inflammatory and anti-inflammatory cytokines.

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.

Publication Type: Case report

Diving Hyperb Med. 2023 December 20;53(4):356−359. doi: 10.28920/dhm53.4.356-359. PMID: 38091597. PMCID: PMC10944661.

Hypoxic loss of consciousness in air diving: two cases of mixtures made hypoxic by oxidation of the scuba diving cylinder

Arnaud Druelle¹, Lucille Daubresse¹, Jean U Mullot², Hélène Streit³, Pierre Louge⁴

¹ Department of Hyperbaric Medicine, Military Teaching Hospital, Sainte-Anne, Toulon, France
² Navy Laboratory for Analysis Surveillance and Expertise, 83000 Toulon, France
³ Medical Center of ATRIA, 90 000 BELFORT, France
⁴ Acute Medicine Department, Hyperbaric Medicine Unit, Geneva University Hospitals, rue Gabrielle-Perret-Gentil 4, 1205 Geneva, Switzerland

Corresponding author: Dr Arnaud Druelle, Department of Hyperbaric Medicine, Military Teaching Hospital, HIA Ste Anne, 2 boulevard Ste Anne, BP 600, 83800 Toulon CEDEX, France
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Keywords
Case reports; Corrosion; Diving tank; Hypoxia; Oxygen consumption; Rust; Unconsciousness

Abstract

(Druelle A, Daubresse L, Mullot JU, Streit H, Louge P. Hypoxic loss of consciousness in air diving: two cases of mixtures made hypoxic by oxidation of the scuba diving cylinder. Diving and Hyperbaric Medicine. 2023 December 20;53(4):356−359. doi: 10.28920/dhm53.4.356-359. PMID: 38091597. PMCID: PMC10944661.)
Without an adequate supply of oxygen from the scuba apparatus, humans would not be able to dive. The air normally contained in a scuba tank is dry and free of toxic gases. The presence of liquid in the tank can cause corrosion and change the composition of the gas mixture. Various chemical reactions consume oxygen, making the mixture hypoxic. We report two cases of internal corrosion of a scuba cylinder rendering the respired gas profoundly hypoxic and causing immediate hypoxic loss of consciousness in divers.

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.

Publication Type: Case report

Diving Hyperb Med. 2023 December 20;53(4):360. doi: 10.2980/dhm53.4.360. PMID: 38091598. PMCID: PMC10944660.

University of Auckland Postgraduate Diploma in Diving and Hyperbaric Medicine

Michael Davis

Corresponding address: PO Box 35, Tai Tapu 7645, New Zealand
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Keywords
Diving medicine; Hyperbaric medicine; Education; Qualifications

Copyright: This article is the copyright of the author who grants Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.

Publication Type: Letter to the Editor

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Category: Information

06 December 2022

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Click to download each article. This will download a PDF that is password protected from any changes, these individual article PDFs are not for public distribution and for society members personal use. 

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06 December 2022

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2024 March;54(1) 

Diving Hyperb Med. 2024 31 March;54(1):2−8. doi: 10.28920/dhm54.1.2-8. PMID: 38507904. PMCID: PMC11227965.

Efficacy of searching in biomedical databases beyond MEDLINE in identifying randomised controlled trials on hyperbaric oxygen treatment

Hira Khan¹, Mohammad Sindeed Islam², Manvinder Kaur³, Joseph K Burns^1,3, Cole Etherington^1,3, Pierre-Marc Dion², Sarah Alsayadi⁴, Sylvain Boet^1,3,5,6

¹ Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, ON, Canada
² Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
³ Department of Anesthesiology and Pain Medicine, The Ottawa Hospital, Ottawa, ON, Canada
⁴ Faculty of Science, University of Ottawa, Ottawa, ON, Canada
⁵ Department of Innovation in Medical Education, University of Ottawa, Ottawa, ON, Canada
⁶ Institut du Savoir Montfort, Ottawa, ON, Canada

Corresponding author: Dr Sylvain Boet, 1053 Carling Avenue, Ottawa, ON K1Y 4E9, ON, Canada
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Keywords
Biomedical databases; Research methods; Systematic review

Abstract
(Khan K, Islam MS, Kaur M, Burns JK, Etherington C, Dion P-M, Alsayadi S, Boet S. Efficacy of searching in biomedical databases beyond MEDLINE in identifying randomised controlled trials on hyperbaric oxygen treatment. Diving and Hyperbaric Medicine. 2024 31 March;54(1):2−8. doi: 10.28920/dhm54.1.2-8. PMID: 38507904. PMCID: PMC11227965.)
Introduction: Literature searches are routinely used by researchers for conducting systematic reviews as well as by healthcare providers, and sometimes patients, to quickly guide their clinical decisions. Using more than one database is generally recommended but may not always be necessary for some fields. This study aimed to determine the added value of searching additional databases beyond MEDLINE when conducting a literature search of hyperbaric oxygen treatment (HBOT) randomised controlled trials (RCTs).
Methods: This study consisted of two phases: a scoping review of all RCTs in the field of HBOT, followed by a  a statistical analysis of sensitivity, precision, ‘number needed to read’ (NNR) and ‘number unique’ included by individual biomedical databases. MEDLINE, Embase, Cochrane Central Register of Control Trials (CENTRAL), and Cumulated Index to Nursing and Allied Health Literature (CINAHL) were searched without date or language restrictions up to December 31, 2022. Screening and data extraction were conducted in duplicate by pairs of independent reviewers. RCTs were included if they involved human subjects and HBOT was offered either on its own or in combination with other treatments.
Results: Out of 5,840 different citations identified, 367 were included for analysis. CENTRAL was the most sensitive (87.2%) and had the most unique references (7.1%). MEDLINE had the highest precision (23.8%) and optimal NNR (four). Among included references, 14.2% were unique to a single database.
Conclusions: Systematic reviews of RCTs in HBOT should always utilise multiple databases, which at minimum include MEDLINE, Embase, CENTRAL and CINAHL.

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.

Publication Type: Original article

Diving Hyperb Med. 2024 31 March;54(1):9−15. doi: 10.28920/dhm54.1.9-15. PMID:38507905. PMCID: PMC11227964.

Hyperbaric oxygen treatment for infants: retrospective analysis of 54 patients treated in two tertiary care centres

Kubra Ozgok Kangal¹, Bengusu Mirasoglu²

¹ Department of Underwater and Hyperbaric Medicine, University of Health Sciences, Gulhane Faculty of Medicine, Gulhane Research and Training Hospital, Ankara, Turkey
² Department of Underwater and Hyperbaric Medicine, Istanbul University, Istanbul Faculty of Medicine, Istanbul, Turkey

Corresponding author: Associate Professor Kubra Ozgok Kangal, Gen. Dr. Tevfik Saglam Cad. SBÜ-Gülhane Eğitim ve Araştırma Hastanesi, Sualtı Hekimliği ve Hiperbarik Tıp Kliniği, Etlik/Ankara, Turkey
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Keywords
Hyperbaric medicine; Neonate; Newborn; Premature

Abstract
(Ozgok Kangal K, Mirasoglu B. Hyperbaric oxygen treatment for infants: retrospective analysis of 54 patients treated in two tertiary care centres. Diving and Hyperbaric Medicine. 2024 31 March;54(1):9−15. doi: 10.28920/dhm54.1.9-15. PMID:38507905. PMCID: PMC11227964.)
Introduction: We aimed to analyse the outcomes of hyperbaric oxygen treatment (HBOT) and describe difficulties encountered in infants, a rare patient population in this therapeutic intervention, with limited scientific reports.
Methods: This was a retrospective analysis of patients 12 months old or younger who underwent HBOT in two different institutions. Demographic data, clinical presentation, HBOT indication, chamber type, oxygen delivery method, total number of treatments, outcome and complications were extracted from clinical records.
Results: There were 54 infants in our study. The patients’ median age was 3.5 (range 0–12) months. The major HBOT indication was acute carbon monoxide intoxication (n = 32). A total of 275 HBOT treatments were administered, mostly performed in multiplace chambers (n = 196, 71%). Only one patient (2%) required mechanical ventilation. Acute signs were fully resolved in the most patients (n = 40, 74%). No complications related to HBOT were reported.
Conclusions: This study suggests that HBOT may be a safe and effective treatment for infants. Paediatricians should consider HBOT when indicated in infants even for the preterm age group.

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.

Publication Type: Original article

Diving Hyperb Med. 2024 31 March;54(1):16−22. doi: 10.28920/dhm54.1.16-22. PMID: 38507906. PMCID: PMC11227960.

Effect of hyperbaric oxygen treatment on ischaemia-reperfusion injury in rats detorsioned after experimental ovarian torsion

Eralp Bulutlar¹, Ali Yilmaz², Gizem Berfin Uluutku Bulutlar³, Yavuz Aslan⁴, Hale Nur Bozdağ⁵, Zafer Küçükodaci⁶

¹ Zeynep Kamil Gynecology and Obstetrics Training and Research Hospital, İstanbul, Turkey
² Kartal Lütfü Kırdar Training and Research Hospital İstanbul, Turkey
³ Haydarpaşa Numune Training and Research Hospital, İstanbul, Turkey
⁴ Sultan Abdulhamid Han Research and Training Hospital
⁵ VM Medical Park Maltepe Hastanesi, İstanbul , Turkey
⁶ Anadolu Sağlık Merkezi, Gebze, Kocaeli, Turkey

Corresponding author: Dr Eralp Bulutlar, Başakşehir Çam and Sakura City Hospital, Başakşehir Olimpiyat Bulvarı Yolu, 34480 Başakşehir, İstanbul, Turkey
ORCiD: 0000-0002-2246-4899
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Keywords
Animal model; Antioxidants; Experimental; Hyperbaric research; Inflammation

Abstract
(Bulutlar E, Yilmaz A, Uluutku Bulutlar GB, Aslan Y, Bozdağ HN, Küçükodaci Z. Effect of hyperbaric oxygen treatment on ischaemia-reperfusion injury in rats detorsioned after experimental ovarian torsion. Diving and Hyperbaric Medicine. 2024 31 March;54(1):16−22. doi: 10.28920/dhm54.1.16-22. PMID: 38507906. PMCID: PMC11227960.)
Introduction: This study aimed to investigate whether hyperbaric oxygen treatment (HBOT) could ameliorate ischaemia-reperfusion injury in a rat model of ovarian torsion-detorsion.
Methods: Twenty-seven rats were divided among four groups: surgical sham rats (S) (n = 6) underwent identical anaesthesia and surgical incisions to other groups (n = 7 per group) but with no ovary intervention; torsion rats (T) underwent laparotomy, ovarian torsion, relaparotomy and sacrifice after three hours; torsion and detorsion rats (T/DT) underwent laparotomy, ovarian torsion (three hours), relaparotomy and detorsion, and sacrifice after one week; torsion, detorsion, hyperbaric oxygen rats (T/DT/HBOT) underwent laparotomy, ovarian torsion, relaparotomy and detorsion, and sacrifice after one week during which HBOT was provided 21 times (100% oxygen at 600 kPa for 50 min). In all groups blood collection for markers of oxidative stress or related responses, and ovary collection for histology were performed after sacrifice.
Results: When the T/DT, and T/DT/HBOT groups were compared, 8-hydroxy-2′-deoxyguanosine (a marker of oxidative damage to DNA) and malondialdehyde (a product of lipid peroxidation) levels were lower in the T/DT/HBOT group.  Anti-Mullerian hormone levels were higher in the T/DT/HBOT group compared to the T/DT group. In addition, oedema, vascular occlusion, neutrophilic infiltration and follicular cell damage were less in the T/DT/HBOT group 
than in the T/DT group.
Conclusions: When biochemical and histopathological findings were evaluated together, HBOT appeared reduce ovarian ischaemia / reperfusion injury in this rat model of ovarian torsion-detorsion.

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.

Publication Type: Original article

Diving Hyperb Med. 2024 31 March;54(1):23−38. doi: 10.28920/dhm54.1.23-38. PMID: 38507907. PMCID: PMC11065503.

Review of saturation decompression procedures used in commercial diving

Jean-Pierre Imbert¹, Lyubisa Matity², Jean-Yves Massimelli³, Philip Bryson⁴

¹ Divetech, 1543 chemin des vignasses, 06410 Biot, France
² Hyperbaric and Tissue Viability Unit, Gozo General Hospital, Malta
³ CHU de Nice, Hôpital Pasteur, 30 avenue de la voie romaine, 06001 Nice, France
⁴ International SOS, Forest Grove House, Foresterhill Road, Aberdeen, AB25 2ZP, UK

Corresponding author: Jean Pierre Imbert, Divetech, 1543 ch des vignasses 0641Biot, France
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Keywords
Decompression tables; Occupational diving; Saturation diving

Abstract
(Imbert J-P, Matity L, Massimelli J-Y, Bryson P. Review of saturation decompression procedures used in commercial diving. Diving and Hyperbaric Medicine. 2024 31 March;54(1):23−38. doi: 10.28920/dhm54.1.23-38. PMID: 38507907. PMCID: PMC11065503.)
Introduction: This is a review of commercial heliox saturation decompression procedures. The scope does not include compression, storage depth or bell excursion dive procedures. The objectives are to: identify the sources of the procedures; trace their evolution; describe the current practice; and detect relevant trends.
Methods: Eleven international commercial diving companies provided their diving manuals for review under a confidentiality agreement.
Results: Modern commercial diving saturation procedures are derived from a small number of original procedures (United States Navy, Comex, and NORSOK). In the absence of relevant scientific studies since the late 80’s, the companies have empirically adapted these procedures according to their needs and experience. Such adaptation has caused differences in decompression rates shallower than 60 msw, decompression rest stops and the decision to decompress linearly or stepwise. Nevertheless, the decompression procedures present a remarkable homogeneity in chamber PO₂ and daily decompression rates when deeper than 60 msw. The companies have also developed common rules of good practice; no final decompression should start with an initial ascending excursion; a minimum hold is required before starting a final decompression after an excursion dive. Recommendation is made for the divers to exercise during decompression.
Conclusions: We observed a trend towards harmonisation within the companies that enforce international procedures, and, between companies through cooperation inside the committees of the industry associations.

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.

Publication Type: Original article

Full article available here.

Diving Hyperb Med. 2024 31 March;54(1):39−46. doi: 10.28920/dhm54.1.39-46. PMID: 38507908. PMCID: PMC11227959.

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

Benjamin L Turner¹, Pieter-Jan AM van Ooij^1,2, Thijs T Wingelaar^1,3, Rob A van Hulst³, Edwin L Endert1, Paul Clarijs¹, Rigo Hoencamp^4,5,6

¹ Royal Netherlands Navy Diving and Submarine Medical Centre, Den Helder, The Netherlands
² Department of Respiratory Medicine, Amsterdam UMC, Location AMC, University of Amsterdam, Amsterdam, The Netherlands
³ Department of Anesthesiology, Amsterdam UMC, Location AMC, University of Amsterdam, Amsterdam, The Netherlands
⁴ Department of Surgery, Alrijne Hospital, Leiderdorp, the Netherlands
⁵ Trauma Research Unit, Department of Trauma Surgery, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
⁶ Defence Healthcare Organization, Ministry of Defence, Utrecht, the Netherlands

Corresponding author: Mr Benjamin L Turner, Royal Netherlands Navy Diving and Submarine Medical Centre, Den Helder, The Netherlands
ORCiD: 0009-0004-6606-9788
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Keywords
Arterial gas embolism; Decompression sickness; Incidents; Risk factors; Safety; Underwater hazards 

Abstract
(Turner BL, van Ooij P-JAM, Wingelaar TT, van Hulst RA, Endert EL, Clarijs P, Hoencamp R. Chain of events analysis in diving accidents treated by the Royal Netherlands Navy 1966-2023. Diving and Hyperbaric Medicine. 2024 31 March;54(1):39−46. doi: 10.28920/dhm54.1.39-46. PMID: 38507908. PMCID: PMC11227959.)
Introduction: Diving injuries are influenced by a multitude of factors. Literature analysing the full chain of events in diving accidents influencing the occurrence of diving injuries is limited. A previously published ‘chain of events analysis’ (CEA) framework consists of five steps that may sequentially lead to a diving fatality. This study applied four of these steps to predominately non-lethal diving injuries and aims to determine the causes of diving injuries sustained by divers treated by the Diving Medical Centre of the Royal Netherlands Navy.
Methods: This retrospective cohort study was performed on diving injuries treated by the Diving Medical Centre between 1966 and 2023. Baseline characteristics and information pertinent to all four steps of the reduced CEA model were extracted and recorded in a database.
Results: A total of 288 cases met the inclusion criteria. In 111 cases, all four steps of the CEA model could be applied. Predisposing factors were identified in 261 (90%) cases, triggers in 142 (49%), disabling agents in 195 (68%), and 228 (79%) contained a (possible-) disabling condition. The sustained diving injury led to a fatality in seven cases (2%). The most frequent predisposing factor was health conditions (58%). Exertion (19%), primary diver errors (18%), and faulty equipment (17%) were the most frequently identified triggers. The ascent was the most frequent disabling agent (52%).
Conclusions: The CEA framework was found to be a valuable tool in this analysis. Health factors present before diving were identified as the most frequent predisposing factors. Arterial gas emboli were the most lethal injury mechanism.

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

Publication Type: Original article

Diving Hyperb Med. 2024 31 March;54(1):47−56. doi: 10.28920/dhm54.1.47-56. PMID: 38507909.

Reported outcome measures in necrotising soft tissue infections: a systematic review

Jonathan Wackett¹, Bridget Devaney^2,3,4, Raymond Chau⁵, Joshua Ho⁵, Nicholas King⁵, Jasleen Grewal¹, Joshua Armstrong⁶, Biswadev Mitra^2,4

¹ Department of Medicine, Alfred Health, Melbourne, Australia
² Emergency and Trauma Centre, Alfred Health, Melbourne, Australia
³ Department of Intensive Care and Hyperbaric Medicine, Alfred Health, Melbourne, Australia
⁴ Department of Epidemiology and Preventative Medicine, Monash University, Melbourne, Australia
⁵ Monash Health, Melbourne, Australia
⁶ Barwon Health, Geelong, Australia

Corresponding author: Dr Bridget Devaney, Head of Hyperbaric Medicine, Alfred Health, 55 Commercial Road, Melbourne, VIC 3004, Australia
ORCiD: 0000-0001-6521-418X
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Keywords
Fournier’s gangrene; Gas gangrene; Hyperbaric oxygen treatment; Intensive care medicine; Systematic review 

Abstract
(Wackett J, Devaney B, Chau R, Ho J, King N, Grewal J, Armstrong J, Mitra B. Reported outcome measures in necrotising soft tissue infections: a systematic review. Diving and Hyperbaric Medicine. 2024 31 March;54(1):47−56. doi: 10.28920/dhm54.1.47-56. PMID: 38507909. PMCID: PMC11371474.)
Introduction: There are inconsistencies in outcome reporting for patients with necrotising soft tissue infections (NSTI). The aim of this study was to evaluate reported outcome measures in NSTI literature that could inform a core outcome set (COS) such as could be used in a study of hyperbaric oxygen in this indication.
Methods: A systematic review of all NSTI literature identified from Cochrane, Ovid MEDLINE and Scopus databases as well as grey literature sources OpenGrey and the New York Academy of Medicine databases which met inclusion criteria and were published between 2010 and 2020 was performed. Studies were included if they reported on > 5 cases and presented clinical endpoints, patient related outcomes, or resource utilisation in NSTI patients. Studies did not have to include intervention. Two independent researchers then extracted reported outcome measures. Similar outcomes were grouped and classified into domains to produce a structured inventory. An attempt was made to identify trends in outcome measures over time and by study design.
Results: Three hundred and seventy-five studies were identified and included a total of 311 outcome measures. Forty eight percent (150/311) of outcome measures were reported by two or more studies. The four most frequently reported outcome measures were mortality without time specified, length of hospital stay, amputation performed, and number of debridements, reported in 298 (79.5%), 260 (69.3%), 156 (41.6%) and 151 (40.3%) studies respectively. Mortality outcomes were reported in 23 different ways. Randomised controlled trials (RCTs) were more likely to report 28-day mortality or 90-day mortality. The second most frequent amputation related outcome was level of amputation, reported in 7.5% (28/375) of studies. The most commonly reported patient-centred outcome was the SF-36 which was reported in 1.6% (6/375) of all studies and in 2/10 RCTs.
Conclusions: There was wide variance in outcome measures in NSTI studies, further highlighting the need for a COS.

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.

Publication Type: Review article

Diving Hyperb Med. 2024 31 March;54(1):57−60. doi: 10.28920/dhm54.1.57-60. PMID: 38507910. PMCID: PMC11227961. 

Equipoise: an important ethical consideration when contemplating participation in a randomised controlled trial of hyperbaric oxygen treatment in necrotising soft tissue infections

Bridget Devaney^1,2,3

¹ Emergency and Trauma Centre, Alfred Health, Melbourne, Australia
² Department of Intensive Care and Hyperbaric Medicine, Alfred Health, Melbourne, Australia 
³ Department of Epidemiology and Preventative Medicine, Monash University, Melbourne, Australia 

Corresponding author: Dr Bridget Devaney, Head of Hyperbaric Medicine, Alfred Health, 55 Commercial Road, Melbourne, VIC 3004, Australia
ORCiD: 0000-0001-6521-418X
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Keywords
Clinical trials; Ethics; Hyperbaric research

Abstract

(Devaney B. Equipoise: an important ethical consideration when contemplating participation in a randomised controlled trial of hyperbaric oxygen treatment in necrotising soft tissue infections. Diving and Hyperbaric Medicine. 2024 31 March;54(1):57−60. doi: 10.28920/dhm54.1.57-60. PMID: 38507910. PMCID: PMC11227961.)
A proposal for a large, multi-centre, randomised controlled trial investigating the role of hyperbaric oxygen treatment (HBOT) in necrotising soft tissue infections (NSTI) has led to much discussion locally and internationally about whether participation is ethical for a centre where stakeholders already consider HBOT standard practice. This article systematically addresses the concept of clinical equipoise specific to the role of HBOT in NSTI, and presents a series of considerations to be taken into account by key stakeholders at potential participating sites.

Copyright: This article is the copyright of the author who grants Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.

Publication Type: World as it is

Diving Hyperb Med. 2024 31 March;54(1):61−64. doi: 10.28920/dhm54.1.61-64. PMID: 38507911. PMCID: PMC11227966.

Secondary deterioration in a patient with cerebral and coronary arterial gas embolism after brief symptom resolution: a case report

Ryota Tsushima¹, Kosuke Mori², Shohei Imaki¹

¹ Yokohama Municipal Citizen’s Hospital 1-1, Mitsuzawanishi-chou, Kanagawa-ku, Yokohama-city, Kanagawa-ken 221-0855, Japan
² Yokohama Minami Kyosai Hospital 1-21-1, Mutsurahigashi, Kanazawa-ku, Yokohama- city, Kanagawa-ken 236-0037, Japan

Corresponding author: Dr Ryota Tsushima, Yokohama Municipal Citizen’s Hospital 1-1, Mitsuzawanishi-chou, Kanagawa-ku, Yokohama-city, Kanagawa-ken 221-0855, Japan
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Keywords
Air embolism; Case reports; Hyperbaric oxygen treatment

Abstract
(Tsushima R, Mori K, Imaki S. Secondary deterioration in a patient with cerebral and coronary arterial gas embolism after brief symptom resolution: a case report. Diving and Hyperbaric Medicine. 2024 31 March;54(1):61−64. doi: 10.28920/dhm54.1.61-64. PMID: 38507911. PMCID: PMC11227966.)
Introduction: Hyperbaric oxygen treatment (HBOT) is recommended for arterial gas embolism (AGE) with severe symptoms. However, once symptoms subside, there may be a dilemma to treat or not.
Case presentation: A 71-year-old man was noted to have a mass shadow in his left lung, and a transbronchial biopsy was performed with sedation. Flumazenil was intravenously administered at the end of the procedure. However, the patient remained comatose and developed bradycardia, hypotension, and ST-segment elevation in lead II. Although the ST changes spontaneously resolved, the patient had prolonged disorientation. Whole- body computed tomography revealed several black rounded lucencies in the left ventricle and brain, confirming AGE. The patient received oxygen and remained supine. His neurological symptoms gradually improved but worsened again, necessitating HBOT. HBOT was performed seven times, after which neurological symptoms resolved almost completely.
Conclusions: AGE can secondarily deteriorate after symptoms have subsided. We recommend that HBOT be performed promptly once severe symptoms appear, even if they resolve spontaneously.

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.

Publication Type: Case report

Diving Hyperb Med. 2024 31 March;54(1):65−68. doi: 10.28920/dhm54.1.65-68. PMID: 38507912. PMCID: PMC11227963.

Hyperbaric oxygen for the treatment of carbon monoxide-induced delayed neurological sequelae: a case report and review of the literature

Zebedee KR Wong¹, Colin KA Teo¹, James WM Kwek¹, Soo Joang Kim², Hooi Geok See³

¹ Navy Medical Service, Republic of Singapore Navy, Singapore
² Hyperbaric and Diving Medicine Centre, Singapore General Hospital, Singapore
³ Division of Anaesthesiology and Perioperative Medicine, Singapore General Hospital, Singapore

Corresponding author: Dr Zebedee KR Wong, Navy Medical Service, Republic of Singapore Navy, Singapore
ORCiD: 0009-0000-0081-3915
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Keywords
Hyperbaric medicine; Morbidity; Pain; Neurology; Psychology; Radiological imaging; Toxicity

Abstract
(Wong ZKR, Teo CKA, Kwek JWM, Kim SJ, See HG. Hyperbaric oxygen for the treatment of carbon monoxide-induced delayed neurological sequelae: a case report and review of the literature. Diving and Hyperbaric Medicine. 2024 31 March;54(1):65−68. doi: 10.28920/dhm54.1.65-68. PMID: 38507912. PMCID: PMC11227963.)
Introduction: Hyperbaric oxygen treatment (HBOT) remains a recognised treatment for acute carbon monoxide (CO) poisoning, but the utility of HBOT in treating CO-induced delayed neurological sequelae (DNS) is not yet established.
Case description: A 26-year old woman presented with reduced consciousness secondary to CO exposure from burning charcoal. She underwent a single session of HBOT with US Navy Treatment Table 5 within six hours of presentation, with full neurological recovery. Eight weeks later, she represented with progressive, debilitating neurological symptoms mimicking Parkinsonism. Magnetic resonance imaging of her brain demonstrated changes consistent with hypoxic ischaemic encephalopathy. The patient underwent 20 sessions of HBOT at 203 kPa (2 atmospheres absolute) for 115 minutes, and received intravenous methylprednisolone 1 g per day for three days. The patient’s neurological symptoms completely resolved, and she returned to full-time professional work with no further recurrence.
Discussion: Delayed neurological sequelae is a well-described complication of CO poisoning. In this case, the patient’s debilitating neurocognitive symptoms resolved following HBOT. Existing literature on treatment of CO-induced DNS with HBOT consists mainly of small-scale studies and case reports, many of which similarly suggest that HBOT is effective in treating this complication. However, a large, randomised trial is required to adequately determine the effectiveness of HBOT in the treatment of CO-induced DNS, and an optimal treatment protocol.

Copyright: This article is the copyright of Case report

Diving Hyperb Med. 2024 31 March;54(1):69−72. doi: 10.28920/dhm54.1.69-72. PMID: 38507913. PMCID: PMC11065502.

The first deep rebreather dive using hydrogen: case report

Richard J Harris¹, Craig J Challen¹, Simon J Mitchell^1,2,3,4

¹ Technical diver, Wetmules Dive Team
² Department of Anaesthesiology, School of Medicine, 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: Professor Simon Mitchell, Department of Anaesthesiology, School of Medicine, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
ORCiD: 0000-0002-5149-6371
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Keywords
Helihydrox; High pressure neurological syndrome; HPNS; Hydreliox; Hydrox; Technical diving; Trimix

Abstract

(Harris RJ, Challen CJ, Mitchell SJ. The first deep rebreather dive using hydrogen: case report. Diving and Hyperbaric Medicine. 2024 31 March;54(1):69−72. doi: 10.28920/dhm54.1.69-72. PMID: 38507913. PMCID: PMC11065502.)
Bounce diving with rapid descents to very deep depths may provoke the high-pressure neurological syndrome (HPNS). The strategy of including small fractions of nitrogen in the respired gas to produce an anti-HPNS narcotic effect increases the gas density which may exceed recommended guidelines. In 2020 the ‘Wetmules’ dive team explored the Pearse Resurgence cave (New Zealand) to 245 m breathing trimix (approximately 4% oxygen, 91% helium and 5% nitrogen). Despite the presence of nitrogen, one diver experienced HPNS tremors beyond 200 m. The use of hydrogen (a light yet slightly narcotic gas) has been suggested as a solution to this problem but there are concerns, including the potential for ignition and explosion of hydrogen-containing gases, and accelerated heat loss. In February 2023 a single dive to 230 m was conducted in the Pearse Resurgence to experience hydrogen as a breathing gas in a deep bounce dive. Using an electronic closed-circuit rebreather, helihydrox (approximately 3% oxygen, 59% helium and 38% hydrogen) was breathed between 200 and 230 m. This was associated with amelioration of HPNS symptoms in the vulnerable diver and no obvious adverse effects. The use of hydrogen is a potential means of progressing deeper with effective HPNS amelioration while maintaining respired gas density within advised guidelines.

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.

Publication Type: Case report

Full article available here.

Diving Hyperb Med. 2024 March 31;54(1):73−74. doi: 10.28920/dhm54.1.73-74. PMID: 38507914.

Time to shock people

Gerard Laden¹, Bruce Mathew¹, Ananthakrishnan Ananthasayanam^1,2

¹ Clinical Hyperbaric Facility, Hull and East Riding Hospital, Anlaby, UK
² Department of Surgery, Hull University Teaching Hospitals, NHS Trust, Hull, UK

Corresponding author: Mr Gerard Laden, Clinical Hyperbaric Facility, Hull and East Riding Hospital, Anlaby, UK 
ORCiD: 0009-0008-0820-8291
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Keywords
Cardiac; CPR, Defibrillation; First aid; Resuscitation

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.

Publication Type: Letter to the Editor

Diving Hyperb Med. 2024 March 31;54(1):74−75. doi: 10.28920/dhm54.1.74-75. PMID: 38507915. PMCID: PMC11227962.

Response to Laden et al.

Andrew Tabner^1,2, Graham Johnson^1,2, Philip Bryson³ on behalf of the authorship team

¹ Emergency Department, Royal Derby Hospital, Uttoxeter Road, Derby, UK, DE22 3NE
² University of Nottingham Medical School, Queen’s Medical Centre, Nottingham, UK, NG7 2UH
³ TAC Healthcare, Wellheads Crescent, Aberdeen, Scotland AB21 7GA

Corresponding author: Dr Andrew Tabner, Emergency Department, Royal Derby Hospital, Uttoxeter Road, Derby, UK, DE22 3NE
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Keywords
Resuscitation; Defibrillation; Mechanical CPR; Cardiovascular; Letters (to the Editor)

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.

Publication Type: Letter to the Editor

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