Acclimatization to diving: a systematic review.

Multiday hyperbaric exposure has been shown to reduce the incidence of decompression sickness (DCS) of compressed-air workers. This effect, termed acclimatization, has been addressed in a number of studies, but no comprehensive review has been published. This systematic review reports the findings of a literature search. PubMed, Ovid Embase, The Cochrane Library and Rubicon Research Repository were searched for studies reporting DCS incidence, venous gas embolism (VGE) or subjective health reports after multiday hyperbaric exposure in man and experimental animals. Twenty-nine studies fulfilled inclusion criteria. Three epidemiological studies reported statistically significant acclimatization to DCS in compressed-air workers after multiday hyperbaric exposure. One experimental study observed less itching after standardized simulated dives. Two human experimental studies reported lower DCS incidence after multiday immersed diving. Acclimatization to DCS has been observed in six animal species. Multiday diving had less consistent effect on VGE after hyperbaric exposure in man. Four studies observed acclimatization while no statistically significant acclimatization was reported in the remaining eight studies. A questionnaire study did not report any change in self-perceived health after multiday diving. This systematic review has not identified any study suggesting a sensitizing effect of multiday diving, and there is a lack of data supporting benefit of a day off diving after a certain number of consecutive diving days. The results suggest that multiday hyperbaric exposure probably will have an acclimatizing effect and protects from DCS. The mechanisms causing acclimatization, extent of protection and optimal procedure for acclimatization has been insufficiently investigated.

Decompression illness and other injuries in a recreational dive charter operation.

INTRODUCTION: Health and safety within the recreational diving industry are poorly described. We aimed to obtain the true prevalence of decompression illness (DCI) and other diving and non-diving injuries, including occupational injuries, in a large recreational diving charter operation. METHODS: A New Zealand recreational diving operator keeps detailed records of diving activity and event/incident reports. We extracted passenger and crew numbers, dive numbers and incident statistics from all boat trips and associated work-related injuries between 01 January 2008 and 31 December 2014. The records of divers referred to the regional hyperbaric unit for suspected DCI were reviewed retrospectively. Using these data the prevalence of DCI and non-diving injuries were calculated. RESULTS: There were 65,536 person-trips to sea and 57,072 divers undertook 97,144 dives. Fifty-five injury events were documented over seven years, 31 in customers and 24 in staff. Four divers (including one staff member) diagnosed with DCI underwent recompression therapy, giving a prevalence of 0.41 cases requiring recompression per 10,000 dives, or one case per 24,386 dives, whilst five other divers were assessed as not having DCI. There was one cardiac-related fatality. Thirty-five non-diving injuries (mainly lacerations and minor musculoskeletal injuries) were documented in 30 people resulting in 10 consulting a general practitioner and seven presenting to the local regional hospital emergency department. CONCLUSIONS: DCI requiring recompression was relatively rare in this supervised recreational diving operation. Minor non-diving injuries were the most common adverse event. Compared to other adventure sports, the prevalence of injury in recreational scuba diving is low.

Risk perception in small-scale fishers and hyperbaric personnel: A risk assessment of hookah diving.

Hookah diving is a fishing method used in many small-scale fisheries in the Gulf of Mexico and the Caribbean Sea, as well as in many coastal fisheries around the world. Many high-value species like sea cucumber and spiny lobster, among others, are harvested via hookah diving. However, the fishing method presents a risk for both decompression illness and carbon monoxide poisoning, both causes of disabilities and death among small-scale fishers, and with significant negative impacts on the social and economic status of households and coastal communities. Currently, there is a misunderstanding among fishers concerning diving risks. Using a mixed-method analysis, this study reports the risk perceptions of small-scale fishers and hyperbaric personnel about hookah diving, and the actual diving accidents which occur in the spiny lobster and sea cucumber fisheries in the Yucatán northeastern ports. The study highlights the need for appropriate fishing technologies and increased awareness among fishers about the consequences of hookah diving. Fishery managers and health services can make priority decisions based on the information generated.

A historical review of the U.S. Navy's busiest recompression chamber in the Pacific theater with a current perspective on caring for civilian divers within its area of responsibility: short communication.

On the island Nation of Guam, the United States Department of Defense has stationed military personnel from every service branch. Guam is utilized as a strategic waypoint for the U.S. military in the Pacific theater. As the largest service branch in the region, the Navy has placed a few Diving Medical Officers in Guam to collectively manage and treat patients with recompression therapy. Guam is also a popular tourist destination, with multiple recreational diving companies certifying individuals who are looking to take advantage of the beautiful warm water and exotic marine life. Unfortunately, with an increase in training and certifying inexperienced divers, came an increase in the operational tempo of the U.S. Navy's recompression chamber on Guam. The recompression chamber on Naval Base Guam (NBG) has been treating patients since 1971. With the only multiplace chamber in the Mariana Islands, Diving Medical Officers, with the accompanying chamber staff, treat military personnel, active-duty sponsored patients and civilian patients. Treating civilian patients by military providers through military treatment facilities presents multiple issues that must be addressed in an effort to provide efficient quality medical care. This article reviews the records, documents, and activity of the NBG chamber over the last four decades. Through the obtained data the information provides projected financial reimbursement from civilian patients. The article also sheds light on areas of needed improvement with regard to data collection, third-party financial collection efforts and the necessity of an inclusive electronic health record (EHR) for military and civilian patients.

Decompressing rescue personnel during Australian submarine rescue operations.

INTRODUCTION: Personnel rescuing survivors from a pressurized, distressed Royal Australian Navy (RAN) submarine may themselves accumulate a decompression obligation, which may exceed the bottom time limits of the Defense and Civil Institute of Environmental Medicine (DCIEM) Air and In-Water Oxygen Decompression tables (DCIEM Table 1 and 2) presently used by the RAN. This study compared DCIEM Table 2 with alternative decompression tables with longer bottom times: United States Navy XVALSS_DISSUB 7, VVAL-18M and Royal Navy 14 Modified tables. METHODS: Estimated probability of decompression sickness (PDCS), the units pulmonary oxygen toxicity dose (UPTD), the volume of oxygen required and the total decompression time were calculated for hypothetical single and repetitive exposures to 253 kPa air pressure for various bottom times and prescribed decompression schedules. RESULTS: Compared to DCIEM Table 2, XVALSS_DISSUB 7 single and repetitive schedules had lower estimated PDCS, which came at the cost of longer oxygen decompressions. For single exposures, DCIEM schedules had PDCS estimates ranging from 1.8% to 6.4% with 0 to 101 UPTD and XVALSS_DISSUB 7 schedules had PDCS of less than 3.1%, with 36 to 350 UPTD. CONCLUSIONS: The XVALSS_DISSUB 7 table was specifically designed for submarine rescue and, unlike DCIEM Table 2, has schedules for the estimated maximum required bottom times at 253 kPa. Adopting these tables may negate the requirement for saturation decompression of rescue personnel exceeding DCIEM limits.

Observed decompression sickness and venous bubbles following 18-msw dive profiles using RN Table 11.

The venous bubble load in the body after diving may be used to infer risk of decompression sickness (DCS). Retrospective analysis of post-dive bubbling and DCS was made on seven studies. Each of these investigated interventions, using an 18 meters of sea water (msw) air dive profile from Royal Navy Table 11 (Mod Air Table), equivalent to the Norwegian Air tables. A recent neurological DCS case suggested this table was not safe as thought. Two-hundred and twenty (220) man-dives were completed on this profile. Bubble measurements were made following 219 man-dives, using Doppler or 2D ultrasound measurements made on the Kisman-Masurel and Eftedal-Brubakk scales, respectively. The overall median grade was KM/EB 0.5 and the overall median maximum grade was KM/EB 2. Two cases of transient shoulder discomfort ("niggles") were observed (0.9% (95% CL 0.1% - 3.3%)) and were treated with surface oxygen. One dive, for which no bubble measurements were made, resulted in a neurological DCS treated with hyperbaric oxygen. The DCS risk of this profile is below that predicted by models, and comparison of the cumulative incidence of DCS of these data to the large dataset compiled by DCIEM [1, 2] show that the incidence is lower than might be expected.

Decompression sickness among diving fishermen in Mexico: observational retrospective analysis of DCS in three sea cucumber fishing seasons.

The probabilities of decompression sickness (DCS) among diving fishermen are higher than in any other group of divers. Diving behavior of artisanal fishermen has been directed mainly to target high-value species. The aim of this study was to learn about the occurrence of DCS derived from sea cucumber harvesting in the Yucatán Peninsula, Mexico. We conducted a retrospective chart review of diving fishermen treated at a multiplace hyperbaric chamber in Tizimín, Mexico. In total, 233 recompression therapies were rendered to 166 diving fishermen from 2014 to 2016. The average age was 36.7 ± 9.2 years (range: 20-59 years); 84.3% had experienced at least one DCS event previously. There was a correlation between age and DCS incidents (F: 8.3; R2: 0.07) and differences in the fishing depth between seasons (H: 9.99; p⟨0.05). Musculoskeletal pain was the most frequently reported symptom. Three divers, respectively, suffered permanent hearing loss, spinal cord injury and fatal outcome. Diving fishermen experience DCS at an alarmingly high rate, probably due to the type of species targeted, given the requirements in each case. Understanding divers' behaviors and their incentives while in pursuit of high-value species such as sea cucumber could help to find ways to mitigate health risks and help enforce regulation.

Decompression illness treated in Denmark 1999-2013.

INTRODUCTION: The incidence, diver characteristics and symptomatology of decompression illness (DCI) in Denmark has not been assessed since 1982, and the presence of long-term residual symptoms among divers receiving hyperbaric oxygen therapy in Denmark has never been estimated to our knowledge. METHODS: We undertook a retrospective study of the incidence and characteristics of DCI cases in Denmark for the period of 1999 to 2013. Medical records and voluntary questionnaires were reviewed, extracting data on age, gender, weight, height, diver certification level, diving experience, number of previous dives, type of diving, initial type of hyperbaric treatment and DCI symptoms. Trend in annual case numbers was evaluated using run chart analysis and Spearman's correlation. Age, height, weight, and BMI were evaluated using linear regression. The presence of long-term residual symptoms was investigated by phone interviewing the subgroup of divers treated in 2009 and 2010. RESULTS: Two-hundred-and-five DCI cases were identified. The average annual case load was 14 with no significant trend during the study period (P = 0.081). Nor did we find any trend in age, weight, height or BMI. The most frequent symptoms were paraesthesia (50%), pain (42%) and vertigo (40%). Thirteen out of the subgroup of 30 divers had residual symptoms at discharge from hospital, and six out of 24 of these divers had residual symptoms at the time of follow-up. CONCLUSIONS: We observed a more than ten-fold increase in DCI-cases since the period 1966-1980. In the subgroup of divers treated in 2009/2010, a quarter had long-term residual symptoms as assessed by telephone interview, which is in keeping with the international literature, but still a reminder that DCI can have life-long consequences.

[Hyperbaric therapy and diving medicine - hyperbaric therapy part 1: evidence-based emergency care]. / Hyperbare Therapie und Tauchmedizin - Hyperbare Therapie Teil 1: evidenzbasierte Akutversorgung.

Hyperbaric oxygen therapy (HBOT), i. e. breathing pure oxygen at elevated ambient pressure, remains the gold standard of care in treating air or gas embolism and decompression illness. Guidelines are less clear on the value of HBOT in acute management of carbon monoxide (CO) poisoning or clostridial necrosis. To evaluate the evidence of clinical efficacy of HBOT we performed a systematic literature review. Part 1 assesses acute indications such as air or gas embolism, decompression sickness, CO-poisoning, clostridialmyonecrosis, necrotizing problem wounds, acute traumatic wounds and arterial retinal occlusion. Part 2 discusses further uses of HBOT as adjuvant treatment and highlights problems in assessing the value of HBOT using evidence-based medicine criteria.

[Hyperbaric therapy and diving medicine - hyperbaric therapy part 2: adjuvant therapy]. / Hyperbare Therapie und Tauchmedizin - Hyperbare Therapie Teil 2: adjuvante Therapieoptionen.

Hyperbaric oxygen therapy (HBOT), i. e. breathing pure oxygen at elevated ambient pressure, remains the gold standard of care in treating air or gas embolism and decompression illness. Guidelines are less clear on the value of HBOT in acute management of carbon monoxide (CO) poisoning or clostridial necrosis. To evaluate the evidence of clinical efficacy of HBOT we performed a systematic literature review. Part 1 assesses acute indications such as air or gas embolism, decompression sickness, CO-poisoning, clostridialmyonecrosis, necrotizing problem wounds, acute traumatic wounds and arterial retinal occlusion. Part 2 discusses further uses of HBOT as adjuvant treatment and highlights problems in assessing the value of HBOT using evidence-based medicine criteria.

A 10-year estimate of the incidence of decompression illness in a discrete group of recreational cave divers in Australia.

INTRODUCTION: The vast majority of freshwater cave diving in Australia occurs within the limestone caves of the Gambier karst in the south-east of South Australia. The incidence of decompression illness (DCI) in cave divers is presumed to be higher than open-water recreational divers because of the greater depths involved, but has not previously been reported. Our aim was to determine the incidence of DCI in cave divers, the patterns of diving and the outcome of hyperbaric treatment. METHODS: This was a retrospective cohort study of cave divers with DCI presenting to the Royal Adelaide Hospital or The Alfred Hospital over a 10-year period between 2002 and 2012. We reviewed case notes of cave divers who were treated for DCI after diving in the Mt Gambier karst. As there are no records of the number of dives performed during the study period we generated a denominator for the incidence of DCI by extrapolating available data and making a number of assumptions about the number of dives per dive permit issued. RESULTS: Sixteen patients were treated for DCI during the study period. The precipitating dive was a single deep decompression dive in seven cases, multiday repetitive dive sequences in eight and a non-decompression dive in one. Three of the 16 cases of DCI involved dives in excess of 90 metres' fresh water (mfw) using trimix. As the total estimated number of dives in the study period was approximately 57,000 the incidence of DCI in Australian cave divers was estimated to be 2.8:10,000 (0.028%). It is possible that the overall incidence of DCI is as high as 0.05%, and even higher when dives to depths greater than 90 mfw are involved. CONCLUSIONS: The estimated incidence of DCS in this series is lower than expected but consistent with other series describing DCI in cold-water recreational diving.

Factors associated with residual symptoms after recompression in type I decompression sickness.

PURPOSE: The aim of this study is to investigate factors associated with residual symptoms after hyperbaric oxygen therapy (HBOT) in type I decompression sickness (DCS). BASIC PROCEDURES: An HBOT registry, which includes patients with type I DCS, was analyzed retrospectively. We divided enrolled patients into two groups; complete resolution group and residual symptom (RS) group after a single HBOT session. We investigated factors associated with residual symptoms at discharge with univariable and multivariable analyses. Restrictive cubic spline curve and a test for trend analysis were used to show the trend of therapeutic response after HBOT based on time from symptom onset to HBOT. MAIN FINDINGS: In a total of 195 patients, 131 (67.2%) patients were included in the RS group after single HBOT. Prolonged time from symptom onset to recompression was independently associated with residual symptoms (P = .004). When patients who underwent recompression within 24 hours from symptom were included in the reference group, the adjusted odds ratios (AOR) (95% confidence interval) of residual symptoms after HBOT were the following: 24 to 96 hours, 2.24 (0.75-6.65); 96 to 240 hours, 3.31 (1.08-10.13); more than 240 hours, 22.83 (2.45-231.43). In terms of sort of diving, commercial and recreational divers had higher probability of residual symptoms than military divers (AOR, 4.78 and 33.36, respectively). PRINCIPAL CONCLUSIONS: Early HBOT is associated with rapid symptom elimination after treatment in type I DCS. Military divers showed a more immediate response after recompression in comparison with commercial and recreational divers.

Fate of abstracts presented at the annual scientific meeting of the Undersea and Hyperbaric Medical Society.

INTRODUCTION: The full-text publication of abstracts presented at any given scientific meeting in peer-reviewed journals is accepted as a measure of scientific quality of that particular meeting. The aim of this study is to determine the full-text publication rate of abstracts presented at the 2005 Scientific Meeting of the Undersea and Hyperbaric Medical Society (UHMS). METHODS: We identified the scientific abstracts presented at the 2005 UHMS meeting and searched the PubMed database (June 2005 to July 2010) for their corresponding full-text publication. We recorded the following parameters for each of the abstracts: number of authors, number of centers involved in the study, statistical methods used, country of origin of the study, study type, and subject of the abstract. We recorded the time to publication and the title of the journal if the abstract had been published in a peer-reviewed journal. RESULTS: Overall, we identified 187 abstracts presented at the 2005 UHMS meeting. Two of the abstracts were excluded from the study because they had been retracted from the meeting and six more because they had been already published as full-text articles at the time the meeting was held. Of the 179 abstracts, 62 (34.6%) were published as full-text articles within the succeeding five years. The mean (+/- SD) time to publication was 18.5 (+/- 13.6) months. Multivariate analysis with logistic regression identified "country of origin" and "the subject of the abstract" as independent predictors of full-text publication. CONCLUSION: We found that only one-third of the abstracts presented at the 2005 UHMS meeting were published as full-text articles within the succeeding five years. Although this rate is consistent with similar studies from various disciplines, further research is needed to identify the specific barriers to full-text publication of abstracts in the field of underwater and hyperbaric medicine.

Arterial gas embolism: a review of cases at Prince of Wales Hospital, Sydney, 1996 to 2006.

Arterial gas embolism may occur as a complication of diving or certain medical procedures. Although relatively rare, the consequences may be disastrous. Recent articles in the critical care literature suggest the non-hyperbaric medical community may not be aware of the role for hyperbaric oxygen therapy in non-diving related gas embolism. This review is part of an Australian appraisal of experience in the management of arterial gas embolism over the last 10 years. We identified all patients referred to Prince of Wales Hospital Department of Diving and Hyperbaric Medicine with a diagnosis of arterial gas embolism from 1996 to 2006. Twenty-six patient records met our selection criteria, eight iatrogenic and 18 diving related. All patients were treated initially with a 280 kPa compression schedule. At discharge six patients were left with residual symptoms. Four were left with minor symptoms that did not significantly impact quality of life. Two remained severely affected with major neurological injury. Both had non-diving-related arterial gas embolism. There was a good outcome in the majority of patients who presented with arterial gas embolism and were treated with compression.

Dysbaric osteonecrosis screening in submarine escape instructors.

INTRODUCTION: Dysbaric osteonecrosis (DON) is an avascular bone necrosis that can be seen in divers and compressed air workers. Submarine escape instructors constitute a specific group who are exposed to hyperbaric conditions with a constant profile. METHODS: We screened 21 Turkish Navy submarine escape instructors and evaluated 147 skeletal radiographs for dysbaric osteonecrosis. Two instructors who had suspicious DON lesions on the X-rays underwent examination by MRI of the suspected sites. RESULTS: We found no evidence of DON in the radiographs and MRIs of the submarine escape instructors. DISCUSSION: We concluded that the risk of DON is very low for submarine escape instructors who work at the Submarine Escape Training Tower (SETT) at a depth of 60 ft and who strictly obey the decompression rules.

Anxiety and panic in recreational scuba divers.

Scuba diving is a high-risk sport; it is estimated that 3 to 9 deaths per 100,000 divers occur annually in the US alone, in addition to increasing numbers of cases of decompression illness each year. However, there has been a tendency within the diving community to de-emphasise the risks associated with scuba diving. While there are numerous factors responsible for the injuries and fatalities occurring in this sport, there is general consensus that many of these cases are caused by panic. There is also evidence that individuals who are characterised by elevated levels of trait anxiety are more likely to have greater state anxiety responses when exposed to a stressor, and hence, this sub-group of the diving population is at an increased level of risk. Efforts to demonstrate that selected interventions such as hypnosis, imagery, mediation and relaxation can reduce stress responses in anxious divers has not yielded consistent findings, and there is a need for systematic research dealing with the efficacy of selected intervention strategies.