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Introduction: The COVID-19 pandemic raised significant concerns about fitness to dive due to potential damage to the pulmonary and cardiovascular systems. Our group previously published guidelines (original and revised) for assessment of these divers. Here, we report a prospective, observational study to evaluate the utility of these guidelines. Methods: Recreational, commercial, and scientific divers with a history of COVID-19 were consented and enrolled. Subjects were evaluated according to the aforementioned guidelines and followed for any additional complications or diving related injuries. Results: One-hundred and twelve divers (56 male, 56 female, ages 19-68) were enrolled: 59 commercial, 30 scientific, 20 recreational, two unknown (not documented), one military. Cases were categorised according to two previous guidelines ('original' n = 23 and 'revised' n = 89): category 0 (n = 6), category 0.5 (n = 64), category 1 (n = 38), category 2 (n = 2), category 3 (n = 1), uncategorisable due to persistent symptoms (n = 1). One hundred divers (89.3%) were cleared to return to diving, four (3.6%) were unable to return to diving, four (3.6%) were able to return to diving with restrictions, and four (3.6%) did not complete testing. Regarding diving related complications, one diver had an episode of immersion pulmonary oedema one year later and one diver presented with decompression sickness and tested positive for COVID-19. Conclusions: Most divers who presented for evaluation were able to return to diving safely. Abnormalities were detected in a small percentage of divers that precluded them from being cleared to dive. Guidelines were easily implemented by a variety of clinicians.
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COVID-19 , Buceo , Guías de Práctica Clínica como Asunto , Humanos , Buceo/efectos adversos , COVID-19/diagnóstico , COVID-19/epidemiología , Masculino , Estudios Prospectivos , Femenino , Persona de Mediana Edad , Adulto , Anciano , Adulto Joven , Examen Físico , SARS-CoV-2RESUMEN
We report an unusual decompression sickness (DCS) incident in a commercial diving project. Eleven divers completed 91 dives to 23.5-36.2 m with bottom times ranging 23-67 min. The divers were breathing compressed air while immersed. Decompression was planned as surface decompression in a deck decompression chamber breathing oxygen typically for 15-30 min. Due to a technical error the divers breathed air rather than oxygen during the surface decompression procedure. Two divers suffered DCS. Both were recompressed on site with the same error resulting in them breathing compressed air rather than oxygen. One of them experienced a severe relapse with cardiovascular decompensation following recompression treatment. While DCS was expected due to the erroneous decompression procedures, it is noteworthy that only two incidents occurred during 91 dives with surface decompression breathing air instead of oxygen. Accounting for this error, the median omitted decompression time was 17 min (range 0-26 min) according to the Bühlmann ZHL-16C algorithm. These observations suggest that moderate omission of decompression time has a relatively small effect on DCS incidence rate. The other nine divers were interviewed in the weeks following completion of the project. None of them reported symptoms at the time, but five divers reported having experienced minor symptoms compatible with mild DCS during the project which was not reported until later.
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Enfermedad de Descompresión , Buceo , Oxígeno , Enfermedad de Descompresión/terapia , Enfermedad de Descompresión/etiología , Humanos , Buceo/efectos adversos , Masculino , Oxígeno/administración & dosificación , Adulto , Factores de Tiempo , Descompresión/métodos , Aire Comprimido/efectos adversos , Persona de Mediana Edad , FemeninoRESUMEN
Introduction: This is a review of commercial heliox saturation decompression procedures. The scope does not include compression, storage depth or bell excursion dive procedures. The objectives are to: identify the sources of the procedures; trace their evolution; describe the current practice; and detect relevant trends. Methods: Eleven international commercial diving companies provided their diving manuals for review under a confidentiality agreement. Results: Modern commercial diving saturation procedures are derived from a small number of original procedures (United States Navy, Comex, and NORSOK). In the absence of relevant scientific studies since the late 80's, the companies have empirically adapted these procedures according to their needs and experience. Such adaptation has caused differences in decompression rates shallower than 60 msw, decompression rest stops and the decision to decompress linearly or stepwise. Nevertheless, the decompression procedures present a remarkable homogeneity in chamber PO2 and daily decompression rates when deeper than 60 msw. The companies have also developed common rules of good practice; no final decompression should start with an initial ascending excursion; a minimum hold is required before starting a final decompression after an excursion dive. Recommendation is made for the divers to exercise during decompression. Conclusions: We observed a trend towards harmonisation within the companies that enforce international procedures, and, between companies through cooperation inside the committees of the industry associations.
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Enfermedad de Descompresión , Buceo , Humanos , Descompresión/efectos adversos , Oxígeno , Helio , Enfermedad de Descompresión/etiologíaRESUMEN
Background: There is an increasing interest in 'transfer under pressure' (TUP) decompression in commercial diving, bridging traditional surface-oriented diving and saturation diving. In TUP diving the diver is surfaced in a closed bell and transferred isobarically to a pressure chamber for final decompression to surface pressure. Methods: Tables for air diving and air and oxygen decompression have been compared for total decompression time (TDT), oxygen breathing time as well as high and low gradient factors (GF high and low). These have been considered surrogate outcome measures of estimated decompression sickness probability (PDCS). Results: Six decompression tables from DadCoDat (DCD, The Netherlands), Defence and Civil Institute of Environmental Medicine (DCIEM, Canada), Comex MT92 tables (France) and the United States Navy (USN) have been compared. In general, USN and DCD procedures advised longer TDT and oxygen breathing time and had a lower GF high compared to MT92 and DCIEM tables. GF low was significantly higher in USN procedures compared to DCD and one of the MT92 tables due to a shallower first stop in many USN profiles compared to the two others. Allowance and restrictions for repetitive diving varied extensively between the six procedures. While USN procedures have been risk-assessed by probabilistic models, no detailed documentation is available for any of the tables regarding validation in experimental and operational diving. Conclusions: Absence of experimental testing of the candidate tables precludes firm conclusions regarding differences in PDCS. All candidate tables are recognised internationally as well as within their national jurisdictions, and final decisions on procedure preference may depend on factors other than estimated PDCS. USN and DCD procedures would be expected to have lower PDCS than MT92 and DCIEM procedures, but the magnitude of these differences is not known.
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Buceo , Humanos , Canadá , Países Bajos , Oxígeno , DescompresiónRESUMEN
Introduction: Performance of routine Chest X-rays (CXRs) in asymptomatic individuals to assess hyperbaric exposure risk is controversial. The radiation risk may overshadow the low yield in many settings. However, the yield may be higher in certain settings, such as tuberculosis-endemic countries. We evaluated the utility of routine CXR in diving and submarine medical examinations in South Africa. Methods: Records of 2,777 CXRs during 3,568 fitness examinations of 894 divers and submariners spanning 31 years were reviewed to determine the incidence of CXR abnormality. Associated factors were evaluated using odds ratios and a binomial logistic regression model, with a Kaplan-Meier plot to describe the duration of service until first abnormal CXR. Results: An abnormal CXR was reported in 1.1% per person year of service, yielding a cumulative incidence of 6.5% (58/894) of the study participants. Only four individuals had a clinical indication for the CXR in their medical history. A range of potential pathologies were seen, of which 15.5% were declared disqualifying and the rest (84.5%) were treated, or further investigation showed that the person could be declared fit. Conclusions: In South Africa, a routine CXR has a role to play in detecting abnormalities that are incompatible with pressure exposures. The highest number of abnormalities were found during the initial examinations and in individuals with long service records. Only four individuals had a clinical indication for their CXR during the 31-year span of our study. Similar studies should be performed to make recommendations in other countries and settings.
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Buceo , Personal Militar , Humanos , Buceo/efectos adversos , Estudios Retrospectivos , Rayos X , Ejercicio FísicoRESUMEN
A recent review suggested that the measure K = t² x pO2 [4.57] (t is exposure time in h, pO in atm) should replace unit pulmonary toxic dose (UPTD) as an exposure index for pulmonary oxygen toxicity (POT) in surface-oriented diving. K would better predict reduction in vital capacity (VC) during exposure and allow prediction of recovery. Although K is more accurate estimating VC changes than UPTD, the calculation of K is more extensive, particularly when estimating hyperoxic exposure for dives with multiple pO2 segments. Furthermore, and in contrast with UPTD, K is difficult to interpret on its own given its non- linear dimension of time. We suggest that a new metric: ESOT (equivalent surface oxygen time) should be used to replace UPTD. ESOT = t x pO2 [2.285] (t is exposure time in minutes, pO in atm). ESOT=1 is thus the hyperoxic exposure reached after one minute of breathing 100% O2 at surface pressure. Hyperoxic monitoring by ESOT is more practical than K to apply in an operational environment, with no loss of accuracy in POT prediction. In addition, it intuitively allows interpreting hyperoxic exposures on its own, analogous to UPTD. The daily hyperoxic threshold limits suggested by Risberg and van Ooij for two, five and an unlimited number of successive diving days would translate to ESOTs of 650, 500 and 420 respectively.
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The Japan "Ordinance on Safety and Health of Work under High Pressure", which is the law regulating health conditions for workers under high pressure environments, was amended in 2014. The revised regulations have highlighted other difficulties and new problems, but they have not yet written an appropriate amendment based on the aspect of occupational and environmental health. Health management for occupational divers and caisson workers in accordance with the new regulations has not determined the best approach to reducing related disorders and will cause other legal problems. This paper presents some issues in the new regulations for hyperbaric workers, which directly or indirectly involve occupational health physicians. Health checkups and work limitations should be done in consideration of the occupational characteristics of the undersea and hyperbaric environment. Regular examinations using specific studies are useful to diagnose the early stages of chronic conditions for workers, and are also useful for determining the hiring suitability for hyperbaric workers. Work limitations should be decided by the conditions that induce serious accidents or disorders that result from exposure to hyperbaric environments, and depend on the obstacles for work due to sequelae of decompression sickness. The new regulations need to be properly revised, based on scientific evidence, to include health management for workers in undersea and hyperbaric environments.
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Salud Ambiental , Médicos Laborales , Humanos , Japón , Progresión de la Enfermedad , Examen FísicoRESUMEN
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.
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Buceo , Ahogamiento , Adulto , Anciano , Australia/epidemiología , Autopsia , Causas de Muerte , Humanos , MasculinoRESUMEN
BACKGROUND: Diving challenges the respiratory system because of the pressure changes, breathing gases, and cardiovascular effects. We aimed to analyse the long term effect of occupational diving on pulmonary functions in terms of diving experience (year), smoking history, and occupational groups (commercial divers and SCUBA instructors). MATERIALS AND METHODS: We retrospectively analysed respiratory system examination results of the experienced occupational divers who were admitted to the Undersea and Hyperbaric Medicine Department for periodic medical examination between January 1, 2013 and February 28, 2019. RESULTS: Sixty-four divers applied to our department. Candidate divers were not included in our study. The mean diving experience (year) was 13.6 ± 7.3. None of the divers complained of pulmonary symptoms. Pulmonary auscultation and chest radiography were normal in all cases. In divers with 20 years or more experience, the FEV1/FVC ratio and FEF25-75(%) was significantly lower (p < 0.001, p < 0.05, respectively). In addition, there was a statistically significant negative correlation between FEV1/FVC ratio and FEF25-75(%) and diving experience (year) (p < 0.05, r = -0.444, p < 0.05, r = -0.300, respectively). As the diving experience increase per 1 year, the FEF25-75(%) value decreases by 1.04% according to linear regression analyses. However, smoking and occupational groups did not show any significant influence on pulmonary function test parameters. CONCLUSIONS: Occupational diving seems to create clinically asymptomatic pulmonary function test changes related to small airway obstruction after long years of exposure.
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Buceo/efectos adversos , Enfermedades Pulmonares/etiología , Enfermedades Profesionales/etiología , Adulto , Femenino , Humanos , Enfermedades Pulmonares/fisiopatología , Masculino , Enfermedades Profesionales/fisiopatología , Capacidad de Difusión Pulmonar/fisiología , Pruebas de Función Respiratoria , Estudios Retrospectivos , Fumar Tabaco/fisiopatología , Capacidad Vital , Adulto JovenRESUMEN
INTRODUCTION: Adult attention-deficit/hyperactivity disorder (ADHD) is associated with increased chance of workplace accidents, psychiatric comorbidities, other risky behaviours and sophisticated psychopharmacological treatment. These factors all contribute to a potentially complex risk profile within the commercial diving context. In order to make informed decisions regarding ADHD and commercial diving, further description of this condition among commercial divers is required. This paper reports on a study that aimed to determine the prevalence of adult ADHD among commercial divers. METHODS: The study used a self-reporting survey-type questionnaire to determine likely diagnosis, based on Diagnostic and Statistical Manual of Mental Disorders, 5th ed. criteria, in a group of 245 commercial divers in South Africa. RESULTS: Fourteen cases (5.7% of the sample) met criteria for ADHD. The majority of the cases presented with combined type, and reflected mild forms of ADHD. Adult ADHD did not appear to occur in significantly different proportions across the biographical variables of age, education or diving qualification. CONLCUSION: Based on this small survey, adult ADHD may be over-represented in commercial diving in South Africa, compared to general workplace populations. However, ADHD may not necessarily be a contra-indication to commercial diving.
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Trastorno por Déficit de Atención con Hiperactividad , Buceo , Adulto , Trastorno por Déficit de Atención con Hiperactividad/epidemiología , Humanos , Prevalencia , Sudáfrica/epidemiología , Encuestas y CuestionariosRESUMEN
INTRODUCTION: Professional divers, like many other specialised occupational groups, are subject to regulatory constraints that include mandatory initial medical certification and routine recertification. The New Zealand system of diver certification and health surveillance has undergone modifications in recent years, but its acceptance among end-users has never been formally assessed. Because of the wide variety of tasks, circumstances and personalities encountered in the diving industry, unanimous satisfaction is an unrealistic expectation, but establishing the current mood of divers in this regard and canvassing opinions on possible improvements is an important step towards optimising the certification process. METHOD: A multi-choice satisfaction questionnaire was added, as a quality assurance measure, to the on-line health questionnaire completed annually by all New Zealand professional divers. A complete 12-month dataset was analysed to determine levels of satisfaction, areas of dissatisfaction and suggestions for improvement. Comparison of the opinions of various diver groups was achieved by stratification into employment-type sub-groups and those working locally, overseas or both. RESULTS: The responses of 914 divers who completed the survey established an 85% satisfaction rate with the existing diver certification system. Dissatisfaction was independent of diving locality. Compliance cost was the most common area of dissatisfaction, particularly among recreational diving instructors. CONCLUSIONS: Most New Zealand professional divers consider the current certification system satisfactory. Effective communication between the regulating authority and divers was identified as an important area for further development.
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Buceo , Satisfacción Personal , Certificación , Humanos , Internet , Nueva Zelanda , Encuestas y CuestionariosRESUMEN
INTRODUCTION: Approximately 77% of professional divers leave the industry within five years of entry, for reasons that are uncertain. One possibility is that attrition is due to ill-health. The health of New Zealand occupational divers is surveyed by a comprehensive medical examination every five years and by a health questionnaire in the intervening years. Divers are thereby confirmed 'fit' annually. The aim of this study was to determine if divers quit the industry due to a health problem not identified by this health surveillance system. METHOD: 601 divers who had left the industry within five years of entry medical examination ('quitters') were identified from a computerised database. One hundred and thirty-six who could be contacted were questioned about their principal reason for quitting. Comparison was made between the health data of all those defined as 'quitters' and a group of 436 'stayers' who have remained active in the industry for over 10 years. RESULTS: Health was the principal reason for abandoning a diving career for only 2.9% of quitters. The overwhelming majority (97.1%) quit because of dissatisfaction with aspects of the work, such as remuneration and reliability of employment. Besides gender, the only significant difference between the health data of quitters and stayers was that smoking was four times more prevalent among quitters. CONCLUSIONS: The key determinant of early attrition from the New Zealand professional diver workforce is industry-related rather than health-related. The current New Zealand diver health surveillance system detects the medical problems that cause divers to quit the industry.
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Buceo , Fumar/epidemiología , Buceo/psicología , Buceo/estadística & datos numéricos , Empleo , Femenino , Humanos , Masculino , Nueva Zelanda , Reproducibilidad de los Resultados , Fumar/efectos adversos , Encuestas y CuestionariosRESUMEN
INTRODUCTION: Surveillance of professional divers' hearing is routinely undertaken on an annual basis despite lack of evidence of benefit to the diver. The aim of this study was to determine the magnitude and significance of changes in auditory function over a 10-25 year period of occupational diving with the intention of informing future health surveillance policy for professional divers. METHODS: All divers with adequate audiological records spanning at least 10 years were identified from the New Zealand occupational diver database. Changes in auditory function over time were compared with internationally accepted normative values. Any significant changes were tested for correlation with diving exposure, smoking history and body mass index. RESULTS: The audiological records of 227 professional divers were analysed for periods ranging from 10 to 25 years. Initial hearing was poorer than population norms, and deterioration over the observation period was less than that predicted by normative data. Changes in hearing were not related to diving exposure, or smoking history. CONCLUSION: Audiological changes over 10 to 25 years of occupational diving were not found to be significantly different from age-related changes. Routine annual audiological testing of professional divers does not appear to be justifiable.
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Buceo , Pérdida Auditiva/etiología , Audición , Índice de Masa Corporal , Buceo/efectos adversos , Audición/fisiología , Pérdida Auditiva/epidemiología , Humanos , Nueva Zelanda , Fumar/efectos adversosRESUMEN
The Eurasian Tunnel is a 5.64-km crossroad tunnel that connects Europe and Asia. Located under the seabed for the first time, 3.34 km of the tunnel that crosses the Bosphorus was built by advanced tunneling techniques. An exclusively designed tunnel boring machine (TBM), which has an operating pressure of 11 bars and a diameter of 13.7 meters was used for boring the seabed tunnel. The deepest point was 106 meters below sea level. One bounce diving period and seven saturation diving periods were needed for the repair and maintenance of the TBM during the project. Total time spent under pressure was 5,763 hours. A saturation decompression chamber for four divers was used for the saturation interventions, and divers breathed trimix at storage and excursion depths. The longest saturation run was the second, with storage at 10 bars and excursions to 10.4 bars. Twenty-three professional divers who were all experienced in compressed-air work were assigned to work on the project. Four dive physicians provided medical support, which included screening of divers before and during the hyperbaric interventions as well as on-site supervision. There were no diving-related accidents. A minor hand trauma, an external otitis and occasional insomnia were non-diving-related health issues that occurred during saturation and bounce diving. To our knowledge, the Eurasian Tunnel was the first project to perform TBM repair operations at such depths under the seabed and the first saturation diving in Turkey. In this report, we aimed to share our experiences of hyperbaric medical consulting in support of this type of tunneling project.
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Aire Comprimido , Descompresión/métodos , Buceo/fisiología , Arquitectura y Construcción de Instituciones de Salud/instrumentación , Arquitectura y Construcción de Instituciones de Salud/métodos , Estaciones de Transporte , Adulto , Asia , Dióxido de Carbono , Buceo/efectos adversos , Buceo/legislación & jurisprudencia , Europa (Continente) , Helio , Humanos , Humedad , Mantenimiento/métodos , Mantenimiento/organización & administración , Masculino , Persona de Mediana Edad , Nitrógeno , Enfermedades Profesionales/etiología , Exposición Profesional , Oxígeno , Presión Parcial , Admisión y Programación de Personal/organización & administración , Aptitud Física , Presión , Trastornos del Inicio y del Mantenimiento del Sueño/etiología , Factores de Tiempo , TurquíaRESUMEN
AIM: To determine whether long-term engagement in occupational diving causes significant changes in spirometric measurements. METHOD: All divers with adequate spirometric records spanning at least 10 years were identified from the New Zealand occupational diver database. Changes in lung function over time were compared with normative values derived using published prediction equations. Any significant changes were tested for correlation with age, duration of occupational diving, gender, smoking history and body mass index (BMI). RESULTS: Spirometry data spanning periods of 10 to 25 years were analysed for 232 divers. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) declined with increasing duration of diving, but slightly less than predicted with increasing age, while peak expiratory flow (PEF) declined more than expected for age in longer-term divers. The changes in PEF were statistically significant, and correlated with duration of diving exposure, initial age and final BMI. Nevertheless, the changes were small and probably clinically insignificant. CONCLUSION: We compared changes in spirometric parameters over long periods of occupational diving with normative data and found no clinically significant differences that could be attributed to diving. We found no justification for routine spirometry in asymptomatic divers.
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Buceo , Pulmón/fisiología , Enfermedades Profesionales/fisiopatología , Espirometría , Adulto , Anciano , Buceo/efectos adversos , Femenino , Volumen Espiratorio Forzado , Humanos , Masculino , Persona de Mediana Edad , Nueva Zelanda , Pruebas de Función Respiratoria , Capacidad VitalRESUMEN
INTRODUCTION: Tasmania's aquaculture industry produces over 40,000 tonnes of fish annually, valued at over AUD500M. Aquaculture divers perform repetitive, short-duration bounce dives in fish pens to depths up to 21 metres' sea water (msw). Past high levels of decompression illness (DCI) may have resulted from these 'yo-yo' dives. This study aimed to assess working divers, using Doppler ultrasonic bubble detection, to determine if yo-yo diving was a risk factor for DCI, determine dive profiles with acceptable risk and investigate productivity improvement. METHODS: Field data were collected from working divers during bounce diving at marine farms near Hobart, Australia. Ascent rates were less than 18 m·min⻹, with routine safety stops (3 min at 3 msw) during the final ascent. The Kisman-Masurel method was used to grade bubbling post dive as a means of assessing decompression stress. In accordance with Defence Research and Development Canada Toronto practice, dives were rejected as excessive risk if more than 50% of scores were over Grade 2. RESULTS: From 2002 to 2008, Doppler data were collected from 150 bounce-dive series (55 divers, 1,110 bounces). Three series of bounce profiles, characterized by in-water times, were validated: 13-15 msw, 10 bounces inside 75 min; 16-18 msw, six bounces inside 50 min; and 19-21 msw, four bounces inside 35 min. All had median bubble grades of 0. Further evaluation validated two successive series of bounces. Bubble grades were consistent with low-stress dive profiles. Bubble grades did not correlate with the number of bounces, but did correlate with ascent rate and in-water time. CONCLUSIONS: These data suggest bounce diving was not a major factor causing DCI in Tasmanian aquaculture divers. Analysis of field data has improved industry productivity by increasing the permissible number of bounces, compared to earlier empirically-derived tables, without compromising safety. The recommended Tasmanian Bounce Diving Tables provide guidance for bounce diving to a depth of 21 msw, and two successive bounce dive series in a day's diving.
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Acuicultura , Enfermedad de Descompresión/diagnóstico por imagen , Buceo/efectos adversos , Eficiencia , Enfermedades Profesionales/diagnóstico por imagen , Enfermedad de Descompresión/etiología , Buceo/fisiología , Humanos , Enfermedades Profesionales/etiología , Estudios Prospectivos , Agua de Mar , Tasmania , Factores de Tiempo , UltrasonografíaRESUMEN
INTRODUCTION: Dive computers are used in some occupational diving sectors to manage decompression but there is little independent assessment of their performance. A significant proportion of occupational diving operations employ single square-wave pressure exposures in support of their work. METHODS: Single examples of 43 models of dive computer were compressed to five simulated depths between 15 and 50 metres' sea water (msw) and maintained at those depths until they had registered over 30 minutes of decompression. At each depth, and for each model, downloaded data were used to collate the times at which the unit was still registering "no decompression" and the times at which various levels of decompression were indicated or exceeded. Each depth profile was replicated three times for most models. RESULTS: Decompression isopleths for no-stop dives indicated that computers tended to be more conservative than standard decompression tables at depths shallower than 30 msw but less conservative between 30-50 msw. For dives requiring decompression, computers were predominantly more conservative than tables across the whole depth range tested. There was considerable variation between models in the times permitted at all of the depth/decompression combinations. CONCLUSIONS: The present study would support the use of some dive computers for controlling single, square-wave diving by some occupational sectors. The choice of which makes and models to use would have to consider their specific dive management characteristics which may additionally be affected by the intended operational depth and whether staged decompression was permitted.