Arterial dissection in scuba divers: a potential adverse manifestation of the physiological effects of immersion.

Introduction: Aortic dissections and dissections of cervical, cerebral, and coronary arteries have been previously reported in scuba divers. These incidents may be the consequence of a variety of physiological effects. We review the reported cases of arterial dissection in scuba divers and discuss potential contributing factors related to immersion and diving. Methods: Medline, CINAHL Plus, and SPORTDiscus were searched for published reports of arterial dissection and the Australasian Diving Safety Foundation fatality database was searched for additional cases from Australia. Identified cases were recorded and scrutinised for possible contributing factors. Results: Nineteen cases of arterial dissection, both fatal and non-fatal, were identified. These included cervical or intracranial artery dissection (n = 14), aortic dissection (n = 4), and coronary artery dissection (n = 1). There were 14 male and five female victims; mean age 44 years (SD 14, range 18-65). Contributing factors may include a combination of vasoconstriction and blood redistribution, untreated hypertension, increased pulse pressure, abnormal neck movement or positioning, constrictive and burdensome equipment, exercise, increased gas density and circuit resistance with concomitant elevated work of breathing, atheroma, and possibly the mammalian dive response. Conclusions: Dissecting aneurysms of the aorta or cervical, cerebral, and coronary arteries should be considered as a potential complication of scuba diving. The development of aneurysms associated with scuba diving is likely multifactorial in pathogenesis. Detailed reporting is important in the evaluation of cases. The potential role of the mammalian dive response as a contributing factor requires further evaluation.

Rebreather Forum Four consensus statements.

Closed circuit rebreathers have been widely adopted by technical divers as tools for reducing gas consumption and extending depth and duration capabilities. Rebreathers are technologically complex with many failure points, and their use appears associated with a higher accident rate than open circuit scuba. Rebreather Forum Four (RF4) was held in Malta in April 2023 attracting approximately 300 attendees and representatives of multiple manufacturers and training agencies. Over two and a half days a series of lectures was given by influential divers, engineers, researchers and educators on topics of contemporary relevance to rebreather diving safety. Each lecture was followed by a discussion session with audience participation. Potential consensus statements were drafted by the authors (SJM and NWP) during the course of the meeting. These were worded to be confluent with some important messages emerging from the presentations and subsequent discussions. The statements were presented one by one in a half-day plenary session of participants, and discussion was invited on each. After discussion and any necessary revision, the participants voted on whether to adopt the statement as a position of the forum. A clear majority was required for acceptance. Twenty-eight statements embracing thematic areas designated 'safety', 'research', 'operational issues', 'education and training', and 'engineering' were adopted. Those statements are presented along with contextualising narrative where necessary. The statements may help shape research and teaching initiatives, and research and development strategies over subsequent years.

Practical Guidance for Crafting Original Research Manuscripts.

Scientific writing relies on an extensive array of written and unwritten rules to balance clarity, relevance, and economy. Careful development can strengthen each element of original research manuscripts. Some strategies are straightforward, including general organization and compliance with submission guidelines. Some aspects are more controversial, such as the subtleties of organizational structure, including claims of novelty, and presentation of limitations in the text. Manuscript crafting is usually improved through mindfulness of economy in presentation and objective restraint in interpretations. Submission to credible peer-reviewed journals can help refine the product. Practical guidelines can help develop reports that are readable, objective, and informative.

Gender Distribution Associated With the Journal Wilderness & Environmental Medicine.

INTRODUCTION: Publication and peer review are fundamental to career advancement in science and academic medicine. Studies demonstrate that women are underrepresented in science publishing. We evaluated the gender distribution of contributors to Wilderness & Environmental Medicine (WEM) from 2010 through 2019. METHODS: We extracted author data from ScienceDirect, reviewer data from the WEM Editorial Manager database, and editorial board data from journal records. Gender (female and male) was classified using automated probability-based assessment with Genderize.io software. RESULTS: A total of 2297 unique authors were published over the 10-y span, generating 3613 authorships, of which gender was classified for 96% (n=3480). Women represented 26% (n=572) of all authors, which breaks down to 22% of all, 19% of first, 28% of second, and 18% of last authorships. Women represented 20% of peer reviewers (508/2517), 20% of reviewers-in-training (19/72), and 16% of editorial board members (7/45). The proportion of female authors, first authors, and reviewers increased over time. Women received fewer invitations per reviewer than men (mean 2.1 [95% CI 2.0-2.3] vs 2.4 [95% CI 2.3-2.5]; P=0.004), accepted reviews at similar rates (mean 73 vs 71%; P=0.214), and returned reviews 1.4 d later (mean 10.4 [CI 9.5-11.3] vs 9.0 d [95% CI 8.5-9.6]; P=0.005). CONCLUSIONS: While female representation increased over the study period, women comprise a minority of WEM authors, peer reviewers, and editorial board members. Gender equity could be improved by identifying and eliminating barriers to participation, addressing any potential bias in review processes, implementing strategies to increase female-authored submissions, and increasing mentorship and training.

Gender Equity in Membership, Leadership, and Award Recognition in the Wilderness Medical Society.

INTRODUCTION: Despite near gender parity for women entering medical careers, women remain underrepresented in medical societies. This study evaluated the gender distribution associated with Wilderness Medical Society (WMS) activities. METHODS: A retrospective review was performed on the gender breakdown of the following WMS members: a single-day 2020 snapshot, conference attendees 2012 through 2020, conference presenters from winter 2017 through winter 2021, and leadership and awards data from 1984 through 2021. Genderize.io was used to generate probability-based gender categorizations (male/female) based on first names or pronoun associations. RESULTS: Gender was assigned in 91% (4043/4461) of 2020 WMS members, 92% (6179/6720) of 2012-2020 conference attendees, and 100% of remaining categories. Women represented 28% (1143/4043) of members, 27% (1679/6179) of conference attendees, 31% (143/465) of all conference presenters, 20% (62/303) of mainstage presenters, 23% (17/75) of all board members, 38% (14/37) of committee chairs, and 10% (2/20) of board presidents. Women received 18% (42/228) of recognition awards and 31% (15/48) of research grants issued. CONCLUSIONS: Although women comprise a minority of WMS participants, gender distribution was similar across categories for membership, conference presenters, total board positions, and research grant awards. Relative underrepresentation was seen in the highest leadership levels, in recognition awards, and in mainstage presenters. Ongoing auditing may help to identify and address sources of bias and/or barriers to participation. Although it is only one of many components of equity, identifying successes and future opportunities for gender balance can strengthen the base of the WMS, promote growth, and ensure a strong leadership pipeline.

Effect of hyperbaric oxygen treatment on patients with reduced left ventricular ejection fraction.

INTRODUCTION: Hyperbaric oxygen treatment (HBOT) is available to a wide spectrum of patients, many with significant co-morbidities. Considering its effects on cardiac physiology and reports of pulmonary oedema following exposure, concerns exist about the safety of patients with compromised cardiac function. Few studies have described adverse events occurring during HBOT and even fewer reports address events arising in the hours following HBOT. A relation between adverse events and cardiac function has not been established. As medical guidance is limited, we aimed to evaluate the risk for patients with reduced left ventricular ejection fraction (LVEF) receiving HBOT. METHODS: This retrospective chart review of patients receiving HBOT from April 2003 through December 2019 at our hospital was designed to describe clinical characteristics of patients and to identify adverse events during HBOT and within 24 hours after HBOT. Patients ≥ 40 years of age with a documented LVEF of ≤ 40% were included. Data are presented as mean (SD) [range] or counts, as appropriate. RESULTS: A total of 23 patients were included in the final analysis, 2 (1) [0-4] patients per year. Patients received 25 (19) [1-60] treatments. Two patients had an episode of acute decompensated heart failure possibly linked to HBOT. CONCLUSIONS: This study described the clinical characteristics of patients with reduced LVEF receiving HBOT and showed reassuring results, with a majority of patients with reduced LVEF tolerating HBOT well. Prospective research is required to more fully assess the risk.

Retrospective review of enquiries to the Québec diving medicine call centre: 2004 through 2018.

INTRODUCTION: The Centre de Médecine de Plongée du Québec (CMPQ) established a bilingual 24-hour dive emergency call line and diving medicine information service in 2004. The toll-free number (888-835-7121) works throughout Canada. Calls and emails (cmpq.cisssca@ssss.gouv.qc.ca) are answered by a CMPQ coordinator or on-call hyperbaric physicians and other consultants as needed. We reviewed 15 years of activity. METHODS: Details of phone calls and email enquiries to the centre were reviewed individually and compiled into a database. Data were analysed to characterise contact volume and issues addressed. Contacts were categorised into five groups: information only (INF); medical opinion required (MOP); medical issue after the critical period of urgency had passed (PUR); current urgent but not immediate life-threatening issue (NLT); and immediate life- or health-threatening issue (ILT). Data presented as mean (standard deviation) or percentage. RESULTS: A total of 3,232 contacts were made from May 2004 through December 2018: 19 (SD 8) per month [215 (70) per year]. Primary issues of concern were: emergency planning (20%); technical (not medical/physiology) questions (16%); otorhinolaryngological (12%); and decompression sickness-related (7%). Categorisation was 52% INF, 28% MOP, 13% PUR, 7% NLT, and 0.1% ILT, with 0.2% lacking sufficient detail to categorise. The nature of the diving activity of interest was determined in 67% of cases: 48% (n = 1,039) professional; 46% (n = 1,008) recreational; and 1% (n = 11) breath-hold. CONCLUSIONS: The call centre serves as a resource to the community, providing information on health and safety for diving in addition to being available to assist with emergent needs.

Recreational diving in persons with type 1 and type 2 diabetes: Advancing capabilities and recommendations.

Diving by persons with diabetes has long been conducted, with formal guidelines published in the early 1990s. Subsequent consensus guidelines produced following a 2005 workshop helped to advance the recognition of relevant issues and promote discussion. The guidelines were intended as an interim step in guidance, with the expectation that revisions should follow the gathering of additional data and experience. Recent and ongoing developments in pharmacology and technology can further aid in reducing the risk of hypoglycemia, a critical acute concern of diving with diabetes. Careful and periodic evaluation remains crucial to ensure that participation in diving activity is appropriate. Close self-monitoring, thoughtful adjustments of medications and meals, and careful review of the individual response to diving can assist in optimising control and ensuring safety. Open communication with diving partners, support personnel, and medical monitors is important to ensure that all are prepared to effectively assist in case of need. Ongoing vigilance, best practice, including graduated clearance for diving exposures and adverse event reporting, are all required to ensure the safety of diving with diabetes and to promote community understanding and acceptance.

Comparison of tissue oxygenation achieved breathing oxygen using different delivery devices and flow rates.

INTRODUCTION: Divers with suspected decompression illness require high concentration oxygen (O2). There are many different O2 delivery devices, with few data comparing their performance. This study evaluated O2 delivery, using tissue O2 partial pressure (PtcO2), in healthy divers breathing O2 via three different delivery devices. METHODS: Twelve divers had PtcO2 measured at six limb sites. Participants breathed O2 from: a demand valve using an intraoral mask with a nose clip (NC); a medical O2 rebreathing system (MORS) with an oronasal mask and with an intraoral mask; and a non-rebreather mask (NRB) at 15 or 10 L·min⁻¹ O2 flow. In-line inspired O2 FIO2) and nasopharyngeal FIO2 were measured. Participants provided subjective ratings of device comfort, ease of breathing, and overall ease of use. RESULTS: PtcO2 values and nasopharyngeal FIO2 were similar with the demand valve with intraoral mask, MORS with both masks and the NRB at 15 L·min⁻¹. PtcO2 and nasopharyngeal FIO2 values were significantly lower with the NRB at 10 L·min⁻¹. The NRB was rated as the most comfortable to wear, easiest to breathe with, and overall the easiest to use. CONCLUSION: Of the commonly available devices promoted for O2 delivery to injured divers, similar PtcO2 and nasopharyngeal FIO2 values were obtained with the three devices tested: MORS with an oronasal or intraoral mask, demand valve with an intraoral mask and NRB at a flow rate of 15 L·min⁻¹. PtcO2 and nasopharyngeal FIO2 values were significantly lower when the flow rate using the NRB was decreased to 10 L·min⁻¹.