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Buzzacott P, editor. DAN Annual Diving Report 2016 Edition: A report on 2014 data on diving fatalities, injuries, and incidents [Internet]. Durham (NC): Divers Alert Network; 2016.

Cover of DAN Annual Diving Report 2016 Edition

DAN Annual Diving Report 2016 Edition: A report on 2014 data on diving fatalities, injuries, and incidents [Internet].

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Section 1Dive Fatalities

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1.1. Introduction

The Sports and Fitness Industry Association 2015 report on participation in scuba estimated there were more than 3,000,000 scuba diving participants in the US during the previous year.1 Without knowing how many of those died while scuba diving overseas, or how many of the divers that died in the US were visitors, based on this number alone we cannot state with certainty what the death rate is with precision. However, to put the risk of dying underwater into context, this year’s number of recreational diving fatalities suggests that around 2 out of every 100,000 recreational divers in the US die while scuba diving each year. This number appears relatively stable over time, despite improvements in equipment utility and reliability.

In 2014 there were an estimated 13,860,956 Emergency Room (ER) admissions in the US and US territories, 1,220 of those (0.009%) were for scuba injuries.2 In the scuba injury pyramid, for each recreational diving fatality we might expect around 20 ER admissions, and many more primary care visits. Therefore, preventive efforts to reduce the raw number of fatalities in recreational diving probably have a cascade effect that reduces ER admissions, then primary care visits, time off work, and eventually even mild discomfort associated with minor injuries. To this aim, DAN prepares this Annual Diving Report to raise awareness of the factors that come into play in recreational diving fatalities in the hope it may better inform the diving community.

The Data Collection Process

The data collection process at DAN starts by first identifying a scuba diving death through internet alerts, news, forums or reports from affiliated organizations such as County Coroners, Public Safety Divers, offices of Medical Examiners or members of the public. News reports, mostly online, are monitored constantly for keywords involving diving deaths and scuba. Families of DAN members, friends, and acquaintances of the deceased who are aware of DAN’s data collection efforts are also valuable sources in the data collection process. The DAN Medical Services Call Center (MSCC) is also an important resource as the DAN Medical Services Department assists with the management of any scuba diving event that is called in, whether the patient is a DAN member or not.

Once identified, each death is classified whether it should be followed up or not. There are three criteria to the dive fatalities data set for whether a case should be followed up on: 1) the dive must be recreational 2) use of scuba or rebreather 3) dive is located in US or Canada. For instance, fatalities that occur in non-recreational dives such as in military, scientific or commercial pursuits would be classified as no-follow. The use of scuba or rebreather equipment is a criteria for dive fatalities research; breath-hold dives or snorkeling fatalities are followed up separately. All fatalities in the US and Canada that are of recreational in nature and use either scuba or rebreather equipment are tagged as follow up cases. Fatalities that occur in foreign countries or involving foreign nationals are tagged as no-follow up unless it appears likely that additional details can be obtained beyond media reports, such as when the body of an American citizen is returned to the US for autopsy.

Investigator and Medical Examiner Reports

Once cases are classified as ‘follow up’, research staff will pursue official investigation and coroner’s reports from the appropriate agencies. Most scuba-related deaths in the US are investigated by local law enforcement agencies or the US Coast Guard (USCG) and are subjected to autopsies. The investigation reports and autopsies are integral in DAN’s research into the cause of scuba-related fatalities. Without access to these reports, it would be virtually impossible to compile enough data for analysis.

Each state in the US has its own set of regulations regarding the release of information in addition to compliance to the federally mandated HIPAA (Health Insurance Portability and Accountability Act of 1996) Privacy Rule. Some states consider law enforcement investigation and medical examiner’s reports to be public information and are released easily while others are governed by more stringent privacy laws. Within each state, sometimes the regulations (and, hence, ease in procuring reports) can also vary from county to county. As presented in Table 1.2-2, the majority of diving deaths in the US occur in Florida and California. Fortunately, these two states have straightforward protocols for requesting and obtaining copies of reports.

Table 1.2-2. Number of fatalities in US and Canada by state or province (n=54).

Table 1.2-2

Number of fatalities in US and Canada by state or province (n=54).

Local investigating agencies (sheriff and police departments) follow similar privacy laws of their respective states as medical examiners. However, since not all the information contained in their reports contain private medical information, they are often able to release reports under the Freedom of Information Act (FOIA).

The US Coast Guard is called after most boating and water related incidents in the coastal regions of the US, and are accustomed at investigating such incidents, making their reports invaluable. Reports for cases that are investigated by the US Coast Guard are posted on their website once completed. However, it may take up to two years after an incident before any case is closed and copies released. The USCG follows FOIA protocols and will not release personal information contained in their reports. A redacted copy, removing all personal and identifying information, is usually provided upon each request. When available, downloaded dive computer profiles are included in each case file.

Reports from Witnesses and Next-of-Kin

DAN uses the Fatality Reporting Form to collect data from witnesses and family. The form may be downloaded from the DAN website (http://www.diversalertnetwork.org/files/FATform.pdf) or may be requested from the research and medical services department. When necessary, the family of the decedent or next-of-kin may be contacted to assist in data collection. They may complete the Fatality Reporting Form and/or provide authorization for the release of their family members’ autopsy reports.

The online incident reporting form on the DAN website (https://www.diversalertnetwork.org/research/incidentReport/) can also be used by family and witnesses to report a fatality and provide additional details regarding any scuba diving fatality.

Data Entry and Analysis

DAN research maintains the scuba diving fatality data in a secure server. Once all pertinent information have been gathered and entered into the database, results are analyzed and published in the DAN Annual Diving Report. The autopsy reports, in particular, are reviewed by pathologists who are experienced in investigating diving related fatalities. The official cause of death may or may not be revised for the purpose of research based on their conclusions.

1.2. Geographic and Seasonal Distribution of Fatalities

DAN identified 188 fatalities worldwide in 2014. Of the 188 fatalities, 146 cases were determined to meet the parameters of the study as seven deaths involved divers that were not recreational diving and 35 breath-hold were excluded. (Breath-hold fatalities are covered separately in Section 4 of this report) The geographic distribution of these fatalities (n=146) is shown in Table 1.2-1. Of the 146 cases, only the 68 American or Canadian deaths were actively investigated by DAN. Reports of dive-related deaths from other regions were recorded but, due to geographical limitations, were not investigated. Table 1.2-2 shows the geographic distribution of 2014 Canadian or US fatalities by state or province. Florida again leads in the number of US diving fatalities reported to DAN, followed by California and then Washington. These three states accounted for 26 (48%) of the 54 diving fatalities within the US or Canada reported to DAN in 2014.

Table 1.2-1. DAN-received notifications about fatalities by country and region (n=146).

Table 1.2-1

DAN-received notifications about fatalities by country and region (n=146).

Figure 1.2-1 shows the occurrence of fatalities in 2014 by month. The number of fatalities reported to DAN typically increases as summer approaches, peaks around July and then diminishes as winter approaches. Individual years differ slightly to the longer term average, due to the smaller number involved in a single year.

Figure 1.2-1. Monthly distribution of diver deaths (n=68).

Figure 1.2-1

Monthly distribution of diver deaths (n=68).

1.3. Source of Information

Autopsies were available for 33 out of 68 (49%) US and Canadian cases, as shown in Table 1.3.1 below. The body of the decedent was not recovered in six cases (9%).

Table 1.3.1. Medical examination data (n=68).

Table 1.3.1

Medical examination data (n=68).

1.4. Age and Health of Decedents

Figure 1.4-1 shows the age distribution for dive fatalities. In 81% of cases, the victims were males (n=55), and in 19%, females (n=13). Eighty-four percent of males and 69% of females were 40 years or older. Fifty-three percent of male and 54% of female victims were 50 years old or more.

Figure 1.4-1. Overall distribution of fatalities by age and sex (n=68).

Figure 1.4-1

Overall distribution of fatalities by age and sex (n=68).

Case 1-01: Sudden cardiac death in an elderly male with known heart disease

A 69-year-old male, with unknown certification level or experience was diving at 55 fsw (17 msw). After only three to four minutes, he indicated that he needed to surface. He ascended with a dive guide and immediately began to vomit froth. He was pulled onto the boat, was non-responsive and no pulse was found so CPR commenced. This continued until the dive boat reached the shore where there was an AED available. No shock was advised by the AED. When asked, his travel companion said that the patient had a medical history that included cardiac problems and there was a scar on his chest indicating surgery. The autopsy concluded the cause of death was sudden cardiac death in an elderly male with known heart disease and previous heart-valve surgery.

Medical history was incomplete or unknown in most cases. It was explicitly reported that there were no known medical conditions in 3 cases (4%). The most frequently reported medical conditions in decedents were high blood pressure (n=4; 6%) and heart disease (n=3; 4%).

The true prevalence of high blood pressure and cardiovascular diseases among victims is not known. The numbers presented in Table 1.4-1 represent only the number of cases with known medical histories. The medical history was not known for many cases and some of those who were reportedly healthy may have had undiagnosed hypertension, heart disease or diabetes, as is often the case in the general population.

Table 1.4-1. Known medical history of decedents (n=16).

Table 1.4-1

Known medical history of decedents (n=16).

Body mass index (BMI) was indicated in the autopsy reports of 35 victims (51%) as shown in Figure 1.4-2. According to the Center for Disease Control (CDC) classifications, 20% of victims with known BMI classified as normal weight (18.5-24.9 kg·m-2), 29% as overweight (25.0-29.9 kg·m-2) and 51% as obese (30.0-39.9 kg·m-2). This prevalence of obesity among scuba fatalities is greater than that found in the wider US population, at 35%.3 Data for the wider scuba diving population is not available however; therefore, we cannot know if obesity is more common in divers than in the wider population, and/or if obesity is linked with an increased risk of dying while scuba diving.

Figure 1.4-2. Classification of fatalities by BMI (CDC classifications).

Figure 1.4-2

Classification of fatalities by BMI (CDC classifications).

1.5. Diving Certification and Experience

Information about certification was available in 23 cases (34%) as shown in Figure 1.5-1. Most victims had basic open water diving certification (n=7) but there were also six with professional dive leadership certifications and four divers with technical certifications.

Figure 1.5-1. Diving certifications of fatality cases (n=68).

Figure 1.5-1

Diving certifications of fatality cases (n=68).

The experience of divers as indicated by the number of years since certification was known in only 14 cases as shown in Figure 1.5-2.

Figure 1.5-2. Number of years since initial certification (n=14).

Figure 1.5-2

Number of years since initial certification (n=14).

Case 1-02: An inexperienced diver in a new BCD sank out of sight

This 30-year-old female, inexperienced diver, was wearing a new BCD for the first time with integrated weights and a 7 mm wetsuit. She and her dive buddy were diving with a group but they lost sight of the group upon entry. They both went down to about 60 ffw (18 mfw). The buddy let go of the victim’s hand prior to ascending so that he could inflate his BCD. He started ascending and assumed the victim was following as he could still see her bubbles. When he reached the surface and the victim did not surface soon after, he called for help. The victim’s body was found two days later by two technical divers in 165 feet of water (50 meters), half buried in mud, the tank empty and the BCD inflated but not lifting. The recovery divers believed the diver was wearing too much weight, (~20 pounds, 9 kg), to establish neutral buoyancy at depth even in a 7mm wetsuit and with an empty aluminum tank. An autopsy was not performed and the cause of death was attributed to drowning.

1.6. Characteristics of Dives

Figure 1.6-1 shows the type of diving activity during the fatal dive. Information for the type of activity was available for 66 cases (97%). Two cases did not have activity listed. Forty-five (66% of cases) of the fatal dives involved pleasure or sightseeing, 14 cases (21%) involved spear fishing, hunting or collecting game, and 8 cases (12%) involved training.

Figure 1.6-1. Diving activity (n=66).

Figure 1.6-1

Diving activity (n=66).

Figure 1.6-2 shows the platform from which the fatal dives began. In most cases, the dive began from a charter boat or private vessel (n=48; 71% of known cases). Dives began from beach or pier in 18 cases (26% of known cases).

Figure 1.6-2. Dive platform (n=68).

Figure 1.6-2

Dive platform (n=68).

Case 1-03: Heavily over weighted diver unable to surface and drowned

The diver was a 41-year-old male, certified advanced open water diver. He was experienced in various dive environments and conditions and had made over 100 lifetime dives, three of them to depths greater than the fatal dive of 105 fsw (32 msw). After reaching depth, the diver spent 10 minutes exploring the reef and also looking for an anchor line. Unable to locate the anchor line, the diver made an ascent in open water. Twenty-three minutes into the dive and fairly close to the surface, the dive buddy ran out of air and was forced to ascend rapidly to the surface, becoming separated from the victim. At about that same time, the victim also ran out of air, but was negatively buoyant and did not surface. The victim removed his 17 lb (8 kg) weight belt, but still sank to the bottom at 112 fsw (34 msw). In addition to wearing a steel tank that was negatively buoyant even when empty, the victim was wearing 50 lbs (23 kg) of lead weight distributed between a weight belt, trim pockets at the rear of the BCD, removable integrated weight pouches and soft weights inside the BCD pockets not designed for carrying weights. When the body was recovered an hour later, the dive tank was empty.

Case 1-04: Divers surfaced to find worsening seas and a drifting boat

The diver was a 32-year-old male with unknown certification or experience. Diving with a buddy, they rented a boat and planned several dives for the day. The weather was turning rough and the pair entered the water, descended the anchor line and secured the anchor under a rock. At the conclusion of the dive, the pair could not find the anchor line. They surfaced and found the wind was now blowing from the opposite direction and they saw their boat drifting away from them. They swam after the boat but could not catch it. During the chase, they became separated in worsening seas. After swimming for at least one hour, they still had not reached the boat and lost contact with each other. The buddy reached a mooring buoy at a wreck and clung to it until the US Coast Guard rescued him ten hours later. The missing diver was not recovered.

Most dives occurred in ocean/sea environment (n=42, 62%) with a significant number occurring in stationary fresh water (n=14, 21%) and rivers (n=4, 6%). Eight descriptions (12%) of the environment were missing.

Visibility was reported in 21 cases (31%). It was excellent (>50 ft [15 m]) in 10 cases (48% of the 21 cases where it was known), moderate (10-50 ft [3-15 m]) in 8 (38%) and poor (<10 ft [<3 m]) in 3 cases (14%).

Sea conditions (sea state) was reported in 25 cases (37%). Calm seas were noted in 13 (19%), moderate seas in 10 (15%) and rough seas were reported in 2 cases (3%).

Currents were described in 23 cases (34% of total). Currents were strong in 8 cases (12%), slight in 7 cases (10%) or none in 8 cases (12%).

Information about protective suits worn by divers was available in 28 cases (41% of total). Fifteen of the victims (22%) wore wetsuits, two (3%) wore swimsuits or dive skins and 11 (16%) wore drysuits.

Case 1-05: A diver called for help during a drysuit try-dive

This 38-year-old male was a certified diver but not certified for drysuit diving. He was participating in drysuit try-dive. The victim came to the surface in 8-10 feet water calling for help while taking his regulator out of his mouth. He was instructed to inflate his BCD and remove his weight belt, but it appeared to witnesses that the victim was unable to drop his weights. Other divers swam toward him to assist, but the victim sank and did not resurface. Once the victim was brought to the surface, CPR was administered and he was transported to the hospital where he was pronounced dead.

Figure 1.6-3 shows the maximum dive depth reported for known cases (n=45; 66% of total). Fifteen fatal dives (22%) occurred in water up to 30 feet deep, 11 (16%) in the depth range 31-60 feet, 8 (12%) in the depth range 61-90 feet, 5 (7%) in the depth range 91-120 feet, and 1 (1%) occurred in water deeper than 120 feet. Data were not available for 23 cases (34%).

Figure 1.6-3. Maximum depth of the fatal dive (n=45).

Figure 1.6-3

Maximum depth of the fatal dive (n=45).

While at least 19% of the fatal dives were intended as solo dives, most dives started with a dive buddy. Adherence to buddy system diving is difficult to establish retrospectively. When survivors notice that their buddy is missing, it does not necessarily mean that the buddy intentionally separated; it may rather mean that nobody noticed the diver having problems that eventually led to them dying.

Case 1-06: An entangled diver without a buddy to assist

A 58-year-old male was scallop diving off a moored boat with two other people when he failed to resurface. The boat driver radioed in a ‘diver down’ and emergency crews responded, searching the area for several hours. The victim’s body was recovered about four hours after the incident in approximately 60 fsw (18 msw) of water. According to investigators, it seems that the diver was attempting to surface his catch (2 bags weighing approximately 40 lbs) using an air bag. He became entangled in the dive flag line in the process. It appears he attempted to release his weight belt, but it was clipped to his BCD behind his back. He was found with the regulator out of his mouth and his tanks were empty.

Figure 1.6-4. Buddy status during the fatal dive (n=68).

Figure 1.6-4

Buddy status during the fatal dive (n=68).

Open-circuit scuba was used in 62 cases (91%), rebreathers in four (6%) and surface-supply in two cases (3%). Breathing gas was compressed air in 28 cases (41%) and enriched air nitrox was used with scuba in four cases (6%). In one case (1%) oxygen was used and in two cases (3%), a combination of gas mixes were used. Information was not available in 30 cases (44%).

1.7. Analysis of Situations and Hazards

We classified each case according to the phase of the dive in which the incident occurred, and the chronological chain of events ending in death.

1.7.1. Fatalities by dive phase

Dive phases included: a) on the surface before diving, b) descent/early dive, c) on the bottom, d) ascent, e) on the surface after diving and f) upon exiting the water. This information was available in 41 cases (60% of total). Figure 1.7.1-1 shows the phase of the dive when the deceased lost consciousness. As can be seen, in the majority of fatalities the diver lost consciousness underwater.

Figure 1.7.1-1. Distribution of fatalities by the phase of the dive when the deceased lost consciousness (n=68).

Figure 1.7.1-1

Distribution of fatalities by the phase of the dive when the deceased lost consciousness (n=68).

Case 1-07: A diver experienced difficulty underwater

This 61-year-old male dived to a maximum depth of 90 fsw (27 msw). At 75 fsw (23 msw), the diver signaled the dive leader that he was having trouble with his air. The dive leader gave him his octopus and guided him to the anchor line to complete a safety stop. At the boat, the decedent had difficulty breathing and was put on oxygen. After approximately 20 minutes on oxygen, he fainted. He was administered nitrox as the dive boat had by then run out of oxygen. After another 20 minutes, the decedent stopped breathing. CPR was started but the victim did not regain consciousness.

1.7.2. Causes of deaths

Determination of the causes of death was based on: a) autopsy findings and the underlying cause of death reported by the medical examiner, b) dive profile, c) reported sequence of events, d) equipment and gas analysis findings and e) expert opinion of DAN reviewers. The process is described in further detail in a published paper.4

Root causes, mechanisms of injuries and causes of death were not established in a large number of cases mostly because of missing information and inconclusive investigation. Based on available data, the most common known triggers were natural disease (18%) and running low on, or out of, air (9%) (Table 1.7.2-1).

Table 1.7.2-1. Common triggers by year and overall (n=68).

Table 1.7.2-1

Common triggers by year and overall (n=68).

The most common known harmful events were cardiac events (7%) and insufficient breathing gas (7%) (Table 1.7.2-2).

Table 1.7.2-2. Harmful events (n=68).

Table 1.7.2-2

Harmful events (n=68).

The cause of death as established by medical examiners, in most cases, was drowning. However, according to expert reviewers, once again the data indicated that a leading cause of disabling injuries was an acute cardiac event. Table 1.7.2-3 and Table 1.7.2-4 list the disabling injuries and causes of death and Figure 1.7.2-1 compares disabling injuries and causes of death side by side. It can be seen that in 2014 the leading cause of death and leading disabling injury that led to the death was drowning. However, cardiac events and heart problems continue to be a concern.

Table 1.7.2-3. Disabling injuries (n=68).

Table 1.7.2-3

Disabling injuries (n=68).

Table 1.7.2-4. Causes of death (n=68).

Table 1.7.2-4

Causes of death (n=68).

Figure 1.7.2-1. Distribution of three leading disabling injuries and causes of death (n=68).

Figure 1.7.2-1

Distribution of three leading disabling injuries and causes of death (n=68).

Case 1-08: A returning diver suffered a heart attack

A 66-year-old male with unknown certification level and experience was one of five scuba divers planing to visit a shipwreck. He had recently completed a refresher course, but the duration of his prior absence from diving is unknown. He reportedly entered the water showing no signs of trouble, but shortly afterwards was found on the surface unresponsive and without vital signs. Other divers towed him back to the boat where CPR commenced. Despite resuscitation efforts, the victim was pronounced dead at the scene. There was reportedly a strong surface current and the coroner ruled the cause of death as a heart attack.

Case 1-09: A diver suffered chest pain, surfaced and stopped breathing

A 45-year-old male with unknown experience and certification level was on a diving trip with his children. The decedent dived to 100 fsw (30 msw) for 10 minutes then began having trouble as he surfaced from the dive. He complained of chest pain and was assisted onto the boat, where he became unconscious and stopped breathing. CPR was administered and the victim was taken to the marina where paramedics were waiting. He was taken to a local hospital where he was pronounced dead. The autopsy noted mild-to-moderate chronic hypertensive cardiovascular disease.

Discussion

The majority of fatalities occurred in relatively shallow water <60 fsw (18 msw), diving with open circuit, most often with a buddy. It is likely these circumstances are by far the most common among recreational divers in the US and Canada. The three leading modifiable causes of death and disabling injuries were again cardiac events, insufficient gas and arterial gas embolism. That more than half of all recreational diving fatalities were aged 50 or over highlights the importance of maintaining fitness to dive as divers age. High blood pressure and heart disease were the most common pre-existing health conditions known among 2014 diving fatalities, and obesity was more common at 51% than found in the general living population at 35%. It may not be unreasonable to speculate that older, heavier divers with pre-existing heart or blood-pressure conditions are at elevated risk of dying while scuba diving, compared with younger, healthier divers.

1.8. Lobster Diving Fatalities

This year the report lists ten lobster hunting fatalities, 15% of the 68 that occurred during 2014, to highlight the significance of this group among annual recreational diving fatalities. Divers distracted by the hunt are at elevated risk of running out of breathing gas. The underwater hunt itself may contribute to the workload a diver experiences while diving. Carrying a scoop-net, catch-bag, tickle-stick and/or loop all add to the work of moving around and hunters may even cover more ground during a typical dive, compared with underwater photographers, for example. Some lobster divers rarely dive outside of lobster season and returning to diving after an absence also likely adds to a diver’s workload, while the skills needed for efficient buoyancy control and fluid propulsion are being refreshed.

Case 1-10: Low on air diver re-descended for one last lobster

This 22-year-old male died while diving for lobsters with a large group in 40 fsw(12 msw) deep water. The victim and his buddy surfaced as the buddy was low on air. The victim indicated he still had sufficient air and wanted to go down one more time as he had tied his dive flag near a lobster he wanted to catch. After a few minutes, he was observed to be ‘floating’ 15 fsw (5 msw) from the surface. The boat’s dive guide went in to rescue the victim but found him entangled in the dive line and unresponsive. The victim was surfaced and CPR was initiated but he did not regain consciousness and was pronounced dead at the hospital.

Case 1-11: Entangled hose prevented ascent

This 26-year-old female with unknown certification and experience, died while diving for lobster. The victim and buddy were in about 12 fsw (4 msw) of water using a “hookah” surface-supplied breathing apparatus. The victim’s hose got wrapped around a piling. When the buddy tried to free it, his air got cut off so he had to surface. The victim surfaced a few minutes later, but she was face down and not breathing. She was pulled from the water and CPR was performed. The victim was then taken to the hospital where she was pronounced dead.

Case 1-12: Diver separated from the group during a night dive

This 36-year-old male diver died on a night dive after he became separated from friends while hunting for lobsters. His buddies saw the victim’s light heading for shore and so they followed but when they reached the shore, the victim was not there. They started searching and called for help. The victim’s dive light was found several hours later in shallow water and shortly afterward, the decedent was located about a mile offshore.

Case 1-13: Solo diver suffered a cardiovascular death

This 59-year-old male with unknown certification and experience was diving for lobster but did not return to the boat and was reported missing by his diving companions. The victim had entered the water with two buddies but each went a separate way to hunt for lobster. The two buddies returned to the boat and realized that the victim had not returned for a new tank or left lobster aboard. The victim’s body was found more than an hour later, still clad in dive gear, in the shallows about a half mile from his boat. The autopsy found the cause of death was due to atherosclerotic cardiovascular disease.

Case 1-14: Diver lost consciousness soon after entering the water

This 68-year-old female, with unknown certification level but an experienced diver, was diving from a boat with friends. The victim was briefly underwater to hunt for lobsters in about 10 fsw (3 msw) of water before she lost consciousness. Friends say they saw her struggling on the surface after being underwater for only a few minutes. They pulled her into the boat, began CPR, and called the Coast Guard for help. The Coast Guard brought the victim to shore and paramedics took the victim to the hospital where she was pronounced dead.

Case 1-15: Equipment problems led to death before the dive even began

This 38-year-old male was diving at night for lobster with two friends from aboard a privately owned boat. The victim was using borrowed equipment that he was unfamiliar with. He had problems with the equipment at the surface pre-dive and started drifting away from the boat. His BCD inflator hose was out of reach behind his left shoulder and he did not release his weight belt. The buddy tried to assist the diver, and attempted to share air and inflate the victim’s BCD but this was unsuccessful. By that time, the buddy was now gasping for breath himself. The buddy could not hold on to the negatively buoyant victim as he sank below the surface. Lifeguards found the victim below the surface, removed his weight belt, inflated the BCD, surfaced and pulled him into the lifeguard boat. The victim was unresponsive and did not have a pulse. CPR was performed but the diver was later pronounced dead at the hospital.

Case 1-16: A solo diver found unconscious near his boat

This 53-year-old male was an experienced master diver who was diving alone while hunting for lobster. His unconscious body was found by fishermen floating face down near his boat. Later, it was learned that the decedent was taking prescription medications for both high blood pressure and high cholesterol. The medical examiner ruled that death was due to drowning after an acute myocardial infarct.

Case 1-17: A new drysuit too difficult to master by reading the instructions alone

This 40-year-old male was an advanced open water diver, experienced and had been on several dive trips with colleagues in previous years. This trip was planned to coincide with the start of the lobster season. This was the first time the diver was wearing a new drysuit and he was likely over-weighted. He was seen reading the instructions for his new drysuit the night before the fateful dive. The following day, he was seen struggling to descend head-first, as one would while wearing a wetsuit. Drysuit divers, however, more commonly initially descend feet first to allow trapped air to escape through the shoulder valve. That evening, the victim initially entered the water without the drysuit zip closed. After exiting the water for the deckhand to close the zip, the victim then re-entered the water while wearing wet undergarments. He was diving with a steel tank, a borrowed weight belt with 10-12 lbs (4-5 kg) of lead attached, two weight-integrated removable BCD pouches each containing six lbs and there were another two five lbs weights in pockets at the rear of the BCD, all newly purchased the day before. The victim was also wearing ankle weights making a total of about 35 lbs (16 kg) of ballast in addition to the steel tank. The victim was on his third dive of the day and was diving alone (solo) in 110 fsw (34 msw) when the incident occurred. Approximately 25 minutes after entering the water, the diver surfaced, yelled for help, re-sank underwater and remained missing until the body was recovered three days later with his weight belt ditched, but with weights still in the BCD and on his ankles. His dive tank was empty.

Case 1-18: The exertion of hunting may have been the final straw

This approximately 40-year-old male diver with unknown experience or certification level experienced chest pain on a night dive. Other divers at the site pulled him out of the water and commenced CPR before a rescue boat arrived. The victim was transferred to a hospital where he was pronounced dead.

Case 1-19: Heart failure while separated from group

This 49-year-old male, went on a three day dive trip with two buddies. During the fourth dive of the day, the decedent surfaced early for an unknown reason. The victim complained of nausea during the trip but was unsure if this was a result of sea sickness. The divers were not diving as a group and the decedent was last seen approximately 20 minutes into the dive, at about 20 fsw (6 msw) depth, with no problems. Shortly after the others surfaced, the decedent was found floating face down on the surface of the water and was pulled into the boat and life saving measures were attempted. The diver did not regain consciousness and death was pronounced. The decedent did not have a primary care physician and had not been diagnosed with medical ailments. An autopsy was conducted and the cause of death was determined to be a result of drowning due to congestive heart failure.

Hunting for lobster is an underwater pursuit enjoyed by tens of thousands of Americans and yet each year a very small minority die or are seriously injured. In 2014 there were are least ten lobster hunting fatalities that occurred while breathing compressed gas and the above case vignettes reinforce the importance of diving with a buddy, being familiar with your equipment and keeping an eye on the remaining gas to ensure a safe ascent to the surface. Problems with overweighting are another target for improvement and DAN have a number of tools in development towards this aim.

1.9. Rebreather Fatalities

DAN is aware of 28 rebreather cases in 2014 that occurred worldwide. Four of those (14%) were in the US, where follow-up inquiries usually led to further detailed information. The distribution of rebreather fatalities by country is shown in Table 1.9-1. Vignettes from 11 of the 28 cases follow.

Table 1.9-1. Number of rebreather fatalities by country.

Table 1.9-1

Number of rebreather fatalities by country.

Case 1-20: A 63 year old obese diver could not arrest his descent

This 63-year-old male was an experienced diver but his certification level was unknown. The diver’s medical history included an incomplete bundle branch block, sleep apnea, heart arrhythmia, and he was taking thyroid medication. He was diving wearing a drysuit in a group of three divers to a planned maximum depth of 141 fsw (43 msw). He was last seen by the dive group manipulating something on his equipment after a rapid descent deeper than the maximum planned depth, before again rapidly descending to depths below 170 fsw (52 msw). His dive buddies searched for him for a while (the duration of time is unknown) before surfacing and alerting authorities. The victim’s body was located at 248 fsw (76 msw) several days later using remotely operated underwater vehicles (ROV). The body was not entangled when found.

The equipment investigation identified a leak in the plastic housing of the victim’s BCD inflator valve. When a diluent bottle was attached to the inflator valve and the BCD was filled, bubbles were seen escaping through the plastic although none had been seen by the dive buddies during the fatal dive. It is uncertain if this mechanical issue had any bearing on the outcome. All other equipment was found to be functioning as designed. Cause of death was determined to be sudden death during scuba diving in association with hypertensive and arteriosclerotic cardiovascular disease. The victim had a Body Mass Index of 34.

Case 1-21: Seizures at depth were followed by anoxic brain injury

This was 56-year-old male, experienced diver, dive professional, and technical diver. According to his dive buddy’s dive computer, the pair were at 130 fsw (40 msw) for 20 minutes, and the computer reported five minutes of decompression obligation. They ascended to 85 fsw (26 msw) for a deep stop. At the deep stop, the victim signaled distress to his buddy and reached for his bail out regulator. The victim spat his regulator out and appeared to be having a seizure. The buddy made an emergency ascent with the victim from 85 fsw (26 msw), (during which the victim potentially suffering an arterial gas embolism cannot be ruled out). The victim was taken to the hospital where he was diagnosed with an anoxic brain injury from the delay between spitting out the regulator and commencement of CPR. A series of epileptic seizures were confirmed by electroencephalogram (EEG) twice daily, possibly after experiencing an oxygen toxicity seizure. He died in the hospital six days later when life support was discontinued.

Case 1-22: Diver made a controlled ascent before drowning

This was a 54-year-old male, experienced diver, with certification level unknown. The victim was diving with a group but without an assigned buddy. A member of the group saw the victim signal ‘OK’ before he was found unresponsive in the water a few minutes later. His dive computer showed the diver had ascended in a controlled manner but had omitted required decompression stops. The crew and passengers on the boat attempted CPR until emergency teams arrived. The victim was transported back to shore and pronounced dead. His Body Mass Index was 35 and the post mortem noted left ventricular hypertrophy. The medical examiner concluded, “…that while the decedent appears to have made a controlled ascent to the surface, he was found unresponsive at the surface and made no known cries for help upon reaching it. It therefore appears that he became unresponsive shortly before or after reaching the surface. While his heart disease is a risk for sudden death, a cardiac arrest is expected to be sudden unresponsiveness without [sic] very little warning, and would not be expected to be preceded by a controlled ascent omitting decompression, which indicates awareness of a problem.”

It is, therefore, unclear as to how the decedent became unconscious, but once he became unconscious in the water, he would have drowned. Findings supportive of drowning are pulmonary edema and frothy fluid in the airway. Therefore, based on the autopsy findings and circumstances surrounding the death, as currently understood, the cause of death is listed as drowning while rebreather diving. Listed as contributing factor is hypertensive and atherosclerotic cardiovascular disease. The manner of death is classified as accident.

Case 1-23: Lost diver found the next day in the engine room

This was a 56-year-old male with unknown experience and certification level. On the second dive of the day, the victim and his dive buddies went diving on a shipwreck to 112 fsw (34 msw). The victim became lost in the passageways of the shipwreck and was separated from his dive group. A dive search and rescue team located the victim’s body in the ship’s engine room the following day.

Case 1-24: Skipping the pre-dive check on a misassembled unit proved fatal

This was a 41-year-old female, experienced diver and certified dive instructor. The victim was diving with a group and was brought to the surface by one of her dive buddies. According to the investigative report, poor rebreather design and mistakes during pre-dive equipment assembly were found to have triggered the event. It is not known if the diver assembled the rebreather herself. The oxygen cells had expired in 2013 and were overdue for replacement. An inquest determined that carbon dioxide would not have been removed from the counter lungs due to incorrect equipment assembly, which led to unconsciousness about three minutes into the dive. Specifically, the inhale and exhale counter lungs had been attached on the wrong sides, ensuring the one-way inhale valve was butted up against the one-way exhale valve. This meant the diver was in essence breathing in and out of one counter lung and her exhalations were not passing through the scrubber. Recommended pre-dive checks would have identified the incorrect assembly.

Case 1-25: Diver lost consciousness while diving a shipwreck

This was 57-year-old male, experience and certification unknown. The victim was diving a ship wreck with a group who later surfaced with the unconscious diver. The victim was taken to a local hospital where he was pronounced deceased.

Case 1-26: A 68 year old diver ran out of oxygen before exiting a strong siphon

This was a 68 year-old male who was an experienced professional diver and a certified cave diver. The victim failed to exit the strongly siphoning cave and ran out of oxygen. The victim’s body was recovered at about 131 fsw (40 msw) after about eight hours of searching.

Case 1-27: A problem occurred before entering a cave

This was a 46-year-old male who was an experienced cave and technical diver. Two divers planned to dive to a cave located at 78 fsw (24 msw). According to news reports, one of the victim’s dive computers indicated that at 65 fsw (20 msw) a problem started. This means the incident most likely did not occur in the cave. The dive computer indicated the victim stayed at 65 fsw (20 msw) for approximately two minutes, possibly addressing the problem. Then, he made a rapid ascent to the surface.

Case 1-28: A cave diver suffered a pulmonary embolism

This diver was a male of unknown age who was an experienced cave and technical diver. The victim was cave diving with a group of four, in buddy pairs. The victim was found unconscious at the surface by others in the dive group with his rebreather mouthpiece out of his mouth. The victim was recovered by members of the dive group and taken to local hospital, where he later died. According to news reports, the victim died from a pulmonary embolism.

Case 1-29: Diver stuck in a restriction in a deep, cold cave

A party of five cave divers intended to complete a scooter-assisted traverse through a cave flooded with cold snowmelt, reaching greater than 130 mfw (425 ffw) maximum depth. This was the victim’s first attempt at this traverse. After an hour of diving, and having passed the deepest section, the victim became stuck in a restriction at 110 mfw (360 ffw) depth and signaled distress to his dive buddy. The buddy attempted to lend assistance but the victim became more agitated and died, wedged in the restriction. By now substantially delayed, the buddy exited after making many hours of decompression and was hospitalized for decompression sickness. Official attempts to recover the victim’s body were unsuccessful. Members of the original team returned to extricate the victim, plus a second diver who died during the same dive.

Case 1-30: A second death followed aborting the traverse

The second fatality during this dive involved one of the party of three divers following the first pair. When they reached the first victim stuck in the restriction the first diver of these three negotiated his way around the first victim while the second victim and his buddy turned back towards the entry lake. The second victim died returning through the deepest part of the traverse.

Conclusion

Rebreather diving and rebreather fatalities are growing in frequency. Reading through the 2014 cases should give pause to older rebreather divers with high body mass index and/or existing health conditions. There comes a point in every diver’s life when it is prudent to simply accept that his or her most challenging dives have already been made, and it is time to reduce the physiological stress associated with diving. Avoid strong currents, make dives that require carrying less bailout gas, etc, and actively reduce the workload associated with diving.

While rebreathers are continually evolving and their usability has improved greatly over the last decade, they remain an apparatus that deserves current familiarity and not something one should dive with once or twice per year. Divers who do not have the time or ready access to a dive site to maintain their currency with rebreathers are advised to return to open circuit diving.

1.10. References

1.
Sports and Fitness Industry Association. Participation in recreational diving report. Silver Spring, MD: Sports and Fitness Industry Association; 2015.
2.
Consumer Product Safety Commission. National Electronic Injury Surveillance System. 2015. [Accessed 08/29/2016]; Available from: http://www​.cpsc.gov/en​/Research--Statistics​/NEISS-Injury-Data/
3.
Centers for Disease Control and Prevention. Defining Adult Overweight and Obesity. 2016. Accessed 08/28/2016]; Available from: https://www​.cdc.gov/obesity​/adult/defining.html.
4.
Denoble P.J., Caruso J.L., Dear G. de L., Pieper C.F., Vann R.D. Common causes of open-circuit recreational diving fatalities. Undersea Hyperb Med. 2008;35(6):393–406. [PubMed: 19175195]
© 2016 Divers Alert Network.

This work is available under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Bookshelf ID: NBK424397

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