Snorkelling and breath-hold diving fatalities in Australia, 2001 to 2013. Demographics, characteristics and chain of events

Formulating policies and procedures for managing diving related deaths: a whole of state engagement from frontline and hospital services in Tasmania

Introduction

Tasmania is a small island state off the southern edge of Australia where a comparatively high proportion of the 558,000 population partake in recreational or occupational diving. While diving is a relatively safe sport and occupation, Tasmania has a significantly higher diving death rate per head of population than other States in Australia (four times the national diving mortality rate).

Methods

Three compressed gas diving deaths occurred in seven months between 2021-2022 prompting a review of the statewide approach for the immediate response of personnel to diving-related deaths. The review engaged first responders including the Police Marine and Rescue Service, hospital-based departments including the Department of Hyperbaric and Diving Medicine, and the mortuary and coroner's office.

Results

An aide-mémoire for all craft groups, digitalised checklists for first responders (irrespective of diving knowledge), and a single-paged algorithm to highlight inter-agency communication pathways in the event of a diving death were designed to enhance current practices and collaboration.

Conclusions

If used, these aids for managing diving related deaths should ensure that time-critical information is appropriately captured and stored to optimise information provided for the coronial investigation.

Epidemiology of adverse events related to sports among community people: a scoping review

OBJECTIVES

Numerous reports have described injuries and illnesses in competitive athletes, but studies on leisure-time physical activity and associated adverse events in the general population have not been adequately reviewed. This study aimed to summarise the previous findings on this topic.

DESIGN

Scoping review.

DATA SOURCES

PubMed and Ichushi-Web for articles in English and Japanese, respectively (13 April 2023).

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Articles on adverse events related to sports performed by 'individuals and groups active in the community' were included, whereas those on elite athletes, exercise therapy and rehabilitation, and school sports were excluded. Terms related to physical activity, exercise, sports and adverse events were used for the search strategies.

RESULTS

The literature search yielded 67 eligible articles. Most articles were from the USA, Japan and Australia. Running, scuba diving, rugby and soccer were the most commonly reported sports. Adults were the most common age category in the samples. The most commonly reported adverse events were injuries; only 10 articles reported diseases. 13 longitudinal studies reported the frequency of adverse events based on the number of events/participants×exposure.

CONCLUSION

Adverse events such as sports trauma, disability and certain diseases occur sometimes during sporting activities by residents; however, the articles identified in this review showed biases related to the countries and regions where they were published and the sports disciplines and types of adverse events reported, and articles reporting the frequency of adverse events were also limited. This highlights the need for more high-quality observational studies on diverse populations in the future.

Beyond drowning: Characteristics, trends, the impact of exposure on unintentional non-drowning coastal fatalities between 2012 and 22

OBJECTIVES

Drowning has been the focus of coastal safety, but a notable proportion of coastal mortality is due to other causes of death. This study describes that burden and quantifies the impact of exposure on Australian unintentional coastal fatalities not due to drowning.

METHODS

Analyses of Australian non-drowning coastal fatalities (NDCF) between July 2012 and June 2022 were conducted. Population and exposure-based rates were calculated for Australians 16+ years and compared to all-cause mortality rates. Time series analysis was performed using Joinpoint regression.

RESULTS

616 NDCFs were recorded (0.27/100,000 pop.), with a decreasing average annual percent change of -5.1% (95% CI:-9.5 to -0.4). Cardiac conditions were the primary causal factor, involved in 52% of deaths. Higher fatality rates were seen among men and for incidents occurring in rural and remote areas. Fatality rates were disproportionately high among young adults when compared to all-cause mortality.

CONCLUSIONS

Men, young adults, and those living in/visiting regional and remote areas represent high-risk populations. Proximity to emergency services and extended response times represent major determinants of NDCF.

IMPLICATIONS FOR PUBLIC HEALTH

Due to the high prevalence of NDCF, coastal safety practitioners should expand their attention beyond drowning to consider the broader range of coastal hazards and fatality types.

Effects of hyperventilation on repeated breath-holding while in a fasting state: do risks outweigh the benefits?

Breath-holding preceded by either an overnight fast or hyperventilation has been shown to potentiate the risk of a hypoxic blackout. However, no study has explored the combined effects of fasting and hyperventilation on apneic performance and associated physiological responses. Nine nondivers (8 males) attended the laboratory on two separate occasions (≥48 h apart), both after a 12-h overnight fast. During each visit, a hyperoxic rebreathing trial was performed followed by three repeated maximal static apneas preceded by either normal breathing (NORM) or a 30-s hyperventilation (HYPER). Splenic volume, hematology, cardiovascular, and respiratory variables were monitored. There were no interprotocol differences at rest or during hyperoxic rebreathing for any variable (P ≥ 0.09). On nine occasions (8 in HYPER), the subjects reached our safety threshold (oxygen saturation 65%) and were asked to abort their apneas, with the preponderance of these incidents (6 of 9) occurring during the third repetition. Across the sequential attempts, longer apneas were recorded in HYPER [median(range), 220(123-324) s vs. 185(78-296) s, P ≤ 0.001], with involuntary breathing movements occurring later [134(65-234) s vs. 97(42-200) s, P ≤ 0.001] and end-apneic partial end-tidal pressures of oxygen (P ET O 2 ) being lower (P ≤ 0.02). During the final repetition, partial end-tidal pressure of carbon dioxide [(P ET CO 2 ), 6.53 ± 0.46 kPa vs. 6.01 ± 0.45 kPa, P = 0.005] was lower in HYPER. Over the serial attempts, preapneic tidal volume was gradually elevated [from apnea 1 to 3, by 0.26 ± 0.24 L (HYPER) and 0.28 ± 0.30 L (NORM), P ≤ 0.025], with a correlation noted with preapneic P ET CO 2 (r = -0.57, P < 0.001) and P ET O 2 (r = 0.76, P < 0.001), respectively. In a fasted state, preapnea hyperventilation compared with normal breathing leads to longer apneas but may increase the susceptibility to a hypoxic blackout.NEW & NOTEWORTHY This study shows that breath-holds (apneas) preceded by a 12-h overnight fast coupled with a 30-s hyperventilation as opposed to normal breathing may increase the likelihood of a hypoxic blackout through delaying the excitation of hypercapnic ventilatory sensory chemoreflexes. Evidently, this risk is exacerbated over a series of repeated maximal attempts, possibly due to a shift in preapneic gas tensions facilitated by an unintentional increase in tidal volume breathing.

Fatal diving accidents in Genoa (North-West Italy) from 1968 to 2021: Forensic approach and literature review

Scuba diving is one of the most common and practised water sport activities in Genoa, especially in the more recent years. Although scuba diving is generally considered a safe activity, this does not exclude the possibility of serious or fatal accidents from happening. This retrospective study investigates the case history of deaths resulting from diving accidents recorded by the Municipal Morgue of Genoa over a period of 53 years, specifically from 1968 to 2021. Of the total 52 deaths covered by the study, 48 were male with an age range of 16-71 years. In 25 of these subjects, pre-existing pathological conditions of a cardiovascular nature, not recognised at the time of death, were reported. Out of the total deaths studied, 9 subjects died following a diving accident related to free diving, while 43 subjects died from scuba or rebreather diving. Among the latter subjects, the cause of death was attributed to drowning in 17 cases, arterial gas embolism (AGE) from pulmonary over-distension in 11 cases, cardio-circulatory arrest (CA) favoured by pre-existing and non-existing heart disease known prior to the death in 10 cases, decompression sickness (DCS) in 2 cases, a combination of DCS and AGE in 2 cases and oxygen intoxication in 1 case. Twelve of the fatal accidents occurred in the marine area near the village of Arenzano, where the shipwreck of the oil tanker, the "Haven", sank in 1991 and is today the largest shipwreck explored by divers in the Mediterranean Sea. In all cases of diving deaths, a multi-disciplinary approach is important: in particular, the role of the forensic pathologist is essential in order to accurately reconstruct the dynamics of the accident, thus identifying the predisposing or triggering factors that led to death, and defining the cause of it.

Snorkelling and breath-hold diving fatalities in Australian waters, 2014 to 2018

Introduction

This study investigated snorkelling and breath-hold diving deaths in Australia from 2014-2018 and compared these to those from 2001-2013 to identify ongoing problems and assess the effectiveness of countermeasures.

Methods

Media reports and the National Coronial Information System were searched to identify snorkelling/breath-hold diving deaths for 2014-2018, inclusive. Data were extracted from witness and police reports, medical histories, and autopsies. An Excel® database was created and a chain of events analysis conducted. Comparisons were made with the earlier report.

Results

Ninety-one fatalities (78 males, 13 females, median age 48 years [range 16-80]) were identified with one third likely doing some breath-hold diving. Fifty-two of 77 with known body mass index were overweight or obese. Approximately two thirds were inexperienced snorkellers and 64 were alone. Fifty-one were tourists. Planning shortcomings, such as solo diving and diving in adverse conditions, as well as pre-existing health conditions and inexperience predisposed to many incidents. Primary drowning was the likely disabling condition in 39% of cases with drowning recorded as the cause of death (COD) in two thirds. Cardiac events were the likely disabling conditions in 31% although recorded as the COD in 21% of cases.

Conclusions

Increasing age, obesity and associated cardiac disease have become increasingly prevalent in snorkelling deaths and there is a need for improved health surveillance and risk management. Closer supervision of inexperienced snorkellers is indicated. Apnoeic hypoxia from extended breath-holding and poor supervision remain a problem. The increased risk of harvesting seafood in areas frequented by large marine predators needs to be appreciated and managed appropriately.

Effects of hyperventilation on oxygenation, apnea breaking points, diving response, and spleen contraction during serial static apneas

PURPOSE

Hyperventilation is considered a major risk factor for hypoxic blackout during breath-hold diving, as it delays the apnea breaking point. However, little is known about how it affects oxygenation, the diving response, and spleen contraction during serial breath-holding.

METHODS

18 volunteers with little or no experience in freediving performed two series of 5 apneas with cold facial immersion to maximal duration at 2-min intervals. In one series, apnea was preceded by normal breathing and in the other by 15 s of hyperventilation. End-tidal oxygen and end-tidal carbon dioxide were measured before and after every apnea, and peripheral oxygen saturation, heart rate, breathing movements, and skin blood flow were measured continuously. Spleen dimensions were measured every 15 s.

RESULTS

Apnea duration was longer after hyperventilation (133 vs 111 s). Hyperventilation reduced pre-apnea end-tidal CO2 (17.4 vs 29.0 mmHg) and post-apnea end-tidal CO2 (38.5 vs 40.3 mmHg), and delayed onset of involuntary breathing movements (112 vs 89 s). End-tidal O2 after apnea was lower in the hyperventilation trial (83.4 vs 89.4 mmHg) and so was the peripheral oxygen saturation nadir after apnea (90.6 vs 93.6%). During hyperventilation, the nadir peripheral oxygen saturation was lower in the last apnea than in the first (94.0% vs 86.7%). There were no differences in diving response or spleen volume reduction between conditions or across series.

CONCLUSIONS

Serial apneas  revealed a previously undescribed aspect of hyperventilation; a progressively increased desaturation across the series, not observed after normal breathing and could heighten the risk of a blackout.

Measured Submersion Times in Underwater Hockey Are Inconsistent With Its Classification as an Extreme Apneic Sport

Underwater hockey (UWH) is a sport played at the bottom of a pool without the use of breathing devices such as scuba equipment. It has been classified as an extreme apneic sport based on perceptions of prolonged underwater submersion times during play. This study measured 2000 submersion times during UWH games and compared the average measured submersion times to estimates by UWH players and aquatics directors. The average measured submersion time was 11.0 seconds (SD:3.7) with a range of 4 to 27 seconds, but aquatics directors' estimates were over 100 percent longer (22.7 seconds). While observed active drop times typically lasted for 12.1 seconds (SD: 3.7), observed drop times with no puck lasted on average 9.3 seconds (SD:3.0). When compared to director and player estimates, actual/observed drop times were significantly (p<0.05) lower for overall drop times, active drop times, and drop times without a puck. The average submersion times measured in this study more closely resembled competitive swimming, a breathing-controlled sport, and contradicted lay press reports of routine submersion for one to three minutes, which implies a risk for a hypoxic blackout. The results of this study may mitigate safety concerns about UWH as a high-risk sport for a hypoxic blackout.

An underappreciated cause of ocean-related fatalities: A systematic review on the epidemiology, risk factors, and treatment of snorkelling-related drowning

AIM

Snorkelling is a popular aquatic activity which may result in fatal and non-fatal drowning. However, little is known about the scale of injury, factors impacting risk and strategies for prevention. This review assesses the current literature on snorkelling-related drowning with the aim of assessing available data, improving safety recommendations and reducing the global mortality burden.

METHODS

A systematic review of peer-reviewed literature in English, Spanish and Portuguese language published between 1 January 1980 and 31 October 2020 was conducted using the PRISMA guidelines. CINAHL Complete, Embase, Medline (Ovid), PubMed, SafetyLit, SportDiscus and grey literature were searched to identify studies reporting the incidence of fatal and non-fatal snorkelling-related drowning, or associated risk factors, prevention strategies, treatments or casualty characteristics. Quality was assessed using the NIH Quality Assessment Tool.

RESULTS

Forty-three studies were included (26 reporting population data, 17 case series), of which 27 (62.8%) studies reported data from Australia. Incidence was reported as about 8% of total ocean-related drownings. Case series documented 144 fatalities over 17 years. Frequent casualty characteristics include male (82.6%), pre-existing heart disease (59.4%), tourists (73%) who were inexperienced (71.0%), and lack of a buddy system (89.6%). Two at-risk profiles identified were older adult tourists with pre-existing medical conditions and local, experienced spearfishers. Twenty-two expert recommendations were developed to improve the safety of snorkellers related to individuals, tourism companies, government agencies and diving organisations.

CONCLUSION

Snorkelling-related drownings are not infrequent, and there are many opportunities to improve the safety of this activity based on available data.

Arterial blood gas measurements during deep open-water breath-hold dives

Arterial blood gas (ABG) measurements at both maximum depth and at resurfacing prior to breathing have not previously been measured during free dives conducted to extreme depth in cold open-water conditions. An elite free diver was instrumented with a left radial arterial cannula connected to two sampling syringes through a low-volume splitting device. He performed two open-water dives to a depth of 60 m (197', 7 atmospheres absolute pressure) in the constant weight with fins competition format. ABG samples were drawn at 60 m (by a mixed-gas scuba diver) and again on resurfacing before breathing. An immersed surface static apnea, of identical length to the dives and with ABG sampling at identical times, was also performed. Both dives lasted approximately 2 min. Arterial partial pressure of oxygen ([Formula: see text]) increased during descent from an indicative baseline of 15.8 kPa (after hyperventilation and glossopharyngeal insufflation) to 42.8 and 33.3 kPa (dives 1 and 2) and decreased precipitously (to 8.2 and 8.6 kPa) during ascent. Arterial partial pressure of carbon dioxide ([Formula: see text]) also increased from a low indicative baseline of 2.8 kPa to 6.3 and 5.1 kPa on dives 1 and 2; an increase not explained by metabolic production of CO₂ alone since [Formula: see text] actually decreased during ascent (to 5.2 and 4.5 kPa). Surface static apnea caused a steady decrease in [Formula: see text] and increase in [Formula: see text] without the inflections provoked by depth changes. Lung compression and expansion provoke significant changes in both [Formula: see text] and [Formula: see text] during rapid descent and ascent on a deep free dive. These changes generally support predictive hypotheses and previous findings in less extreme settings.NEW & NOTEWORTHY Arterial blood gas measurements at both maximum depth and the surface before breathing on the same dive have not previously been obtained during deep breath-hold dives in cold open-water conditions and competition dive format. Such measurements were obtained in two dives to 60 m (197') of 2 min duration. Changes in arterial oxygen and carbon dioxide (an increase during descent, and a decrease during ascent) support previous observations in less extreme dives and environments.

Snorkelling and breath-hold diving fatalities in New Zealand, 2007 to 2016

INTRODUCTION

New Zealand's (NZ) long coastline offers a diverse underwater environment with abundant opportunities for harvesting seafood and for recreation. Fatalities from snorkelling/breath-hold diving have been reported from the 1960s through to 2006. Those from 2007 to 2016 are reported here.

METHODS

The National Coronial Information System, the Australasian Diving Safety Foundation diving fatality database, and the Water Safety NZ "Drownbase" were searched and additional coronial data provided by the NZ Ministry of Justice. An anonymised database was created and analysed for multiple factors. A chain of events analysis was performed for each case.

RESULTS

There were 38 snorkelling or breath-hold-related deaths in NZ, 33 men and five women. Twenty-nine were breath-hold divers involved in gathering seafood, and six 'surface snorkellers', predominantly sightseeing. Two-thirds were diving alone and/or were not being observed by anyone out of the water. Twenty-eight victims were classified as overweight or obese and 19/38 were Maori. Pre-existing health factors that may have or definitely contributed to the fatality were present in 30 cases. The most common of these were cardiac (18/38). Two divers had insulin-dependent diabetes mellitus, one each epilepsy and asthma whilst cannabis and/or alcohol were possible factors in seven deaths. Five (possibly six) deaths resulted from apnoeic hypoxia.

CONCLUSIONS

Overall, death from snorkelling/breath-hold diving was an uncommon event (38 in 10 years). Poor judgement was a common feature. Middle-aged Maori men with pre-existing disease feature strongly. This suggests an on-going need for appropriate water safety education within and beyond the Maori community.

Fatalities involving divers using surface-supplied breathing apparatus in Australia, 1965 to 2019

INTRODUCTION

This study identified characteristics and diving practices of victims of fatal surface supplied breathing apparatus (SSBA) incidents in Australia from 1965-2019 to determine underlying factors and risks associated with these activities, better educate the diving community and prevent such deaths.

METHODS

A hand search was made of 'Project Stickybeak' reports from 1965-2000 and SSBA fatality data were compared to the Australasian Diving Safety Foundation fatality database. The National Coronial Information System was searched to identify SSBA diving deaths for 2001-2019. Extracted data were collated and analysed using descriptive statistics and Poisson Regression. A chain of events analysis was used to determine the likely sequence of events.

RESULTS

There were 84 identified SSBA-related deaths during the study period. Most victims were relatively young, healthy males (median age 33 years). At least 50% of victims were undertaking work-related diving, and 37% were recreational diving. Equipment issues, mainly compressor-related, were the main contributor, identified as a predisposing factor in 48% of incidents and as triggers in 24%.

CONCLUSIONS

Preventable surface-supplied diving deaths still occur in both occupational and recreational diving, often from poor equipment maintenance and oversight. Incorrect configuration of the SSBA and lack of training remain on-going problems in recreational users. These could be addressed by improved education, and, failing this, regulatory oversight. The increase in health-related incidents in older participants may be controlled to some extent by greater medical oversight, especially in recreational and non-certified occupational divers who should be encouraged to undergo regular diving medical assessments.