Diving and hyperbaric medicine最新文献

Introduction: Hyperbaric oxygen (HBO) is a potential adjunct treatment to improve hearing following acute acoustic trauma. However, the optimal time frame for HBO initiation has not been elucidated.

Methods: Patients exposed to intense noise as part of active military service that met our audiometric criteria were referred for combined HBO (253 kPa for 80 min, treatment numbers titrated to response) and corticosteroid treatment. The primary outcome was defined as an improvement of at least 10 dB in any of the measured high pure tone frequencies (3, 4, 6 or 8 kHz). Additional outcomes included the absolute change in high pure tone (3, 4, 6 and 8 kHz) summation (HPTS), relative change in HPTS compared to baseline (rHPTS) and the proportion of patients returned to auditory combat readiness.

Results: Of 129 ears (103 patients) included in the final analysis, 59/67 (88%) of the patients treated within seven days but only 14/25 (56%) of patients treated 21 days or more from exposure met the primary outcome (Bonferroni adjusted P = 0.002). Similarly, HPTS improvement (55 dB vs -5dB), rHPTS improvement (55% vs 3%) and return to combat readiness (32/56 (57%) vs 3/20 (15%)) were significantly (P < 0.001, P < 0.001 and P = 0.017, respectively) more pronounced in patients treated earlier. These results were unchanged despite adjusting to age, degree of initial hearing loss and the mechanism of injury.

Conclusions: Early initiation of HBO following acute acoustic trauma is associated with improved response to therapy. The optimal treatment latency appears to be within seven days from injury, with response rates dropping when treatment is delayed beyond three weeks.

Introduction: Hyperbaric oxygen therapy (HBOT) is used in critical care for managing certain severe conditions. However, the reliability of infusion pumps under hyperbaric conditions remains a critical concern. This study evaluated the performance of three infusion pump models - the Mindray BeneFusion VP5, Baxter Flo-Gard 6201, and Braun Infusomat Space - under hyperbaric conditions.

Methods: Infusion pumps were modified to deliver flow into an environment pressurised up to 284 kPa. Accuracy of flow delivered into a pressurised monoplace chamber were tested across a range of infusion rates (1-100 mL·h⁻¹), with different absolute chamber pressures during the iso-pressure phase (243-284 kPa) and a range of different pressurisation/decompression rates (6.9-34.5 kPa·min⁻¹).

Results: More than 3.6 million measurements were obtained. At iso-pressure the Mindray BeneFusion VP5 and the Baxter Flo-Gard 6201 under-performed at low infusion rates (< 20 mL·h⁻¹) and over-performed at high infusion rates (> 20 mL·h⁻¹). Both models exhibited significant under-delivery during pressurisation and over-delivery during decompression. For all conditions the Mindray BeneFusion VP5 demonstrated superior performance. The Braun Infusomat Space was unsuitable for hyperbaric use, failing to maintain performance at pressures above 90 kPa.

Conclusions: The Mindray BeneFusion VP5 outperformed the Baxter Flo-Gard 6201 and Braun Infusomat Space under hyperbaric conditions, offering enhanced reliability for critical care HBOT using monoplace chambers. Clinical protocols should prioritise pumps capable of maintaining flow accuracy during pressure fluctuations. These findings inform best practices for infusion pump use in hyperbaric intensive care, addressing a critical gap in HBOT safety and efficacy.

Introduction: Malfunctions and human errors in diving rebreathers can cause hypoxia, hyperoxia, and/or hypercapnia. We evaluated whether a prior unblinded hypoxia experience enhances a diver's ability to recognise hypoxia and initiate self-rescue.

Methods: Forty participants were randomised to receive either an information leaflet describing hypoxia symptoms or an unblinded hypoxia experience, prior to a blinded hypoxia testing exposure during a virtual reality dive over one month later. The primary outcome was the comparison of the proportion of participants in these two groups who initiated self-rescue before reaching a peripheral oxygen saturation of 70% in the blinded exposure. An individual's 'symptom profile' was assessed by comparing symptoms during the unblinded hypoxia experience and blinded testing exposures.

Results: During the blinded hypoxia testing exposure, 18/20 (90%) participants in the hypoxia experience group performed a self-initiated rescue compared to 6/18 (33%) in the information leaflet group (P < 0.001). Participants in the information leaflet group had lower mean SpO₂ (73.4% vs 81.4%, mean difference 8% [95% CI = 2.5-13.5%, P = 0.005]) and lower inhaled oxygen fraction (7.6% vs 9.4%, mean difference 1.8% [95% CI = 0.6-3.1%, P = 0.005]) at self-rescue. The most frequent and severe symptoms were light-headedness and shortness of breath. Of the 20 participants completing both hypoxia exposures, 14 (70%) had a consistent hypoxia symptom profile, which was not related to the ability to recognise hypoxia.

Conclusions: Self-rescue was approximately three times more likely for participants who had previously experienced hypoxia compared to simply receiving information on relevant symptoms. Most participants exhibited a consistent pattern of individual symptoms, which did not result in earlier or improved detection of hypoxia.

Introduction: Necrotising soft tissue infections (NSTI) are serious infections associated with considerable morbidity and mortality. Heterogeneity of outcome reporting in the NSTI literature precludes the synthesis of high-quality evidence. There is substantial interest in studying the efficacy of hyperbaric oxygen treatment as an adjunctive treatment in NSTI. The aim of this study was to develop a set of core outcome measures for future trials evaluating interventions for NSTI.

Methods: A modified Delphi consensus method was used to conduct a three-round survey of a diverse panel of clinicians and researchers with expertise in NSTI, and patients with lived experience of NSTI. Participants rated the preliminary list of outcomes using a 9-point scale from 1 (least important) to 9 (most critical). The a priori definition of consensus required outcomes to be rated critical (score ≥ 7) by ≥ 70% of participants, and not important (score ≤ 3) by ≤ 15% of participants. After meeting consensus, outcomes were removed from subsequent rounds. Outcomes that did not meet consensus were included in subsequent rounds.

Results: Ninety-eight participants from 14 countries registered and 86%, 69% and 57% responded for each round, respectively. Outcome measures quantifying five core areas achieved consensus: Death, surgical procedures of debridements and amputations, functional outcome among survivors, measures of sepsis, including septic shock and organ dysfunction and resource use measured through length of hospital and intensive care unit stay.

Conclusions: This initial core set of outcome measures will be evaluated and optimised and can harmonise outcome measurements for investigations among patients with NSTI.

Introduction: Extreme deep technical diving presents significant physiological challenges. While procedures often blend elements from both recreational and commercial diving, many remain empirical and unvalidated for this purpose. The rise of closed-circuit rebreathers has reduced gas cost and logistical barriers, enabling more divers to reach unprecedented depths. This study, based on the experience of deep divers, explores the limits of extreme-depth diving and the strategies developed to overcome them.

Methods: Eight rebreather divers (one female, seven males) with experience beyond 200 metres depth were interviewed regarding their preparation, planning, and execution of such dives. The dive profiles of their deepest dives were analysed.

Results: All were highly experienced technical divers. The median maximal depth was 227 [209-302] metres, with a median total dive time of 290 [271-395] minutes. The gas density of the trimix mixture, oxygen exposure, and ascent rate consistently exceeded current recommendations. High pressure nervous syndrome did not appear to be a major limiting factor, whereas decompression posed greater challenges. Three divers experienced decompression sickness following their deepest dives, highlighting the uncertainty around decompression procedures.

Conclusions: These dives require rigorous preparation, robust support systems, equipment modifications, and perfect skills to reduce risks, which remain excessively high. Data are lacking to validate current practices. Decompression procedures must be adapted for these demanding mixed-gas dives, which are inevitably prolonged. A dry underwater habitat could improve decompression tolerance. The role of hydrogen as a breathing gas remains uncertain and still needs to be clarified, but some consider it a promising avenue for further exploration.

Pycnodysostosis is a rare lysosomal storage disorder characterised by short stature, craniofacial dysmorphisms, dental anomalies, and increased bone fragility due to osteoclast dysfunction caused by cathepsin K gene mutations. This case report describes a 43-year-old female pycnodysostosis patient with recurrent subtrochanteric fractures and delayed bone healing following multiple surgical interventions, including femoral osteotomy and bone grafting. Despite these efforts, bony union was not achieved. The patient underwent 39 sessions of hyperbaric oxygen therapy (HBOT), administered at 243.2 kPa for 120 minutes daily, five days per week. Post-treatment radiographs revealed significant fracture healing, with improvements continuing one month after therapy. Visual analogue pain scores decreased from 4 to 1, and quality of life (SF-36) improved. HBOT enhances tissue oxygenation, stimulating osteogenesis, neovascularization, and immune responses, while optimising osteoclast function, making it a promising treatment for pycnodysostosis-related fracture complications. Although ideal, a controlled trial of HBOT in this rare disorder is probably unachievable. Nevertheless, this report highlights HBOT as a potentially useful adjunctive treatment for enhancing healing of refractory fractures in pycnodysostosis patients.

This commentary discusses the provision of cardiopulmonary resuscitation to casualties in a diving bell. This single resource consolidates recent advances in the field, published in different medical journals, to support dissemination across the wider diving industry. It summarises the evaluation of techniques for the provision of manual cardiopulmonary resuscitation (CPR) to a seated casualty, including head-to-chest, knee-to-chest, and prone knee-to-chest compression delivery, and concludes that the only safe and potentially effective approach in a diving bell setting without room for a supine casualty is knee-to-chest CPR. The evaluation of a mechanical CPR device is discussed; it is found to be as effective as existing devices and manual CPR in terms of compression efficacy and is well-suited to the setting. The development of a bespoke resuscitation algorithm, together with deviations from accepted advanced life support algorithm principles, is presented. A novel 'upright CPR' technique for the provision of CPR to a seated casualty, developed during the algorithm evaluation process, is described. Finally, areas where evidence is still lacking, and research priorities for the future, are discussed; a key area for future work is the development and testing of a defibrillator suited to a diving bell setting, where space constraints, a heliox atmosphere, and the risk of both fire and rescuer injury are ever-present.

In December, we published an article titled "Dive Medicine Capability at Rothera Research Station (British Antarctic Survey), Adelaide Island, Antarctica" by Wood FNR, Bowen K, Hartley R, et al. The corresponding author would like to include an additional author, as their contribution was significant but was inadvertently omitted in the initial online publication. While this correction has been made in several versions circulated by the journal, not all have been updated. As a result, we are issuing an errata. The title and abstract are as follows: (Wood FNR, Bowen K, Hartley R, Stevenson J, Warner M, Watts D. Dive medicine capability at Rothera Research Station (British Antarctic Survey), Adelaide Island, Antarctica. Diving and Hyperbaric Medicine. 2024 20 December;54(4):320-327. doi: 10.28920/dhm54.4.320-327. PMID: 39675740.) Rothera is a British Antarctic Survey research station located on Adelaide Island adjacent to the Antarctic Peninsula. Diving is vital to support a long-standing marine science programme but poses challenges due to the extreme and remote environment in which it is undertaken. We summarise the diving undertaken and describe the medical measures in place to mitigate the risk to divers. These include pre-deployment training in the management of emergency presentations and assessing fitness to dive, an on-site hyperbaric chamber and communication links to contact experts in the United Kingdom for remote advice. The organisation also has experience of evacuating patients, should this be required. These measures, as well as the significant infrastructure and logistical efforts to support them, enable high standards of medical care to be maintained to divers undertaking research on this most remote continent.

Introduction: Hyperbaric oxygen therapy (HBOT) administers 100% oxygen in a pressurised chamber at pressures above 1 atmosphere absolute. Inside hyperbaric personnel accompany patients during sessions and breathe compressed air, exposing them to risks like decompression illness and respiratory changes. This study investigated whether hyperbaric exposure affects the long-term lung function of inside hyperbaric personnel.

Methods: An analysis was conducted on spirometry data from 14 personnel working between 2012 and 2023. Lung function tests measured forced vital capacity (FVC), forced expiratory volume in one second (FEV1), mid breath forced expiratory flow (FEF25-75), and peak expiratory flow (PEF) before and after hyperbaric exposure. Participants were categorised based on age, body mass index, number of HBOT sessions, and duration of employment.

Results: No clinically or statistically significant differences were found in FVC, FEV1, or PEF measurements before and after hyperbaric exposures (P > 0.05). However, FEF25-75, an indicator of small airway function, showed a (mean) 16% reduction in personnel with more than 150 HBOT sessions (P = 0.038). A post-hoc analysis confirmed a significant difference in FEF25-75 between personnel with fewer than 74 sessions and those with 150 or more sessions (P = 0.015). No clinically significant symptoms such as dyspnoea were reported during the study period.

Conclusions: The FEF25-75 reduction, without changes in FEV1, FVC, or PEF, could be due to improper performance of the FVC manoeuvre. Maintaining pulmonary health in inside hyperbaric personnel is essential, emphasising the importance of accurate FVC execution in assessments. Further studies are recommended to explore the long-term implications of these findings and the effects of repeated hyperbaric exposure on respiratory health.