A review of 149 Divers Alert Network emergency call records involving diving minors.

INTRODUCTION: Minors have been scuba diving for decades, and while the initial concerns about potential long-term complications related to bone development appear to be unfounded, the incidence of scuba diving injuries among them has been poorly studied. METHODS: We reviewed 10,159 cases recorded in the DAN Medical Services call centre database from 2014 through 2016 and identified 149 cases of injured divers younger than 18 years. Records were analysed for case categorisation on the most common dive injuries. Information about demographics, level of training, risk factors, and relevant behavioural aspects were collected when available. RESULTS: While the most common reason for the call was to rule out decompression sickness, the majority of cases pertained to ear and sinus issues. However, 15% of the dive-related injuries involving minors had a final diagnosis of pulmonary barotrauma (PBt). While no reliable data is available on the incidence of PBt in adult divers, the authors' impression based on personal experience suggests that the number of cases of PBt in minors trends higher than in the general diving population. The narratives on some relevant records describe unmanageable levels of anxiety leading to panic. CONCLUSIONS: Based on the results and narratives on these cases, it is reasonable to infer that psychological immaturity, suboptimal management of adverse situations, and inadequate supervision might have led to severe injuries among these minor divers.

Intra-Individual Test-Retest Variation Regarding Venous Gas Bubble Formation During High Altitude Exposures.

INTRODUCTION: Hypobaric decompression sickness remains a problem during high-altitude aviation. The prevalence of venous gas emboli (VGE) serves as a marker of decompression stress and has been used as a method in evaluating the safety/risk associated with aviation profiles and/or gas mixtures. However, information is lacking concerning the variability of VGE formation when exposed to the same hypobaric profile on different occasions. In this paper, intra-individual test-retest variation regarding bubble formation during repeated hypobaric exposures is presented. The data can be used to determine the sample size needed for statistical power.METHOD: A total of 19 male, nonsmoking subjects volunteered for altitude exposures to 24,000 ft (7315 m). VGE was measured using ultrasound scanning and scored according to the Eftedal-Brubakk (EB) scale. Intraindividual test-retest variation in bubble formation (maximum VGE) was evaluated in subjects exposed more than once to hypobaric pressure. The statistical reliability was examined between paired exposures using the Intraclass Correlation test. G*Power version 3.1.9.6 was used for power calculations.RESULTS: During repeated 20-30 and 70-min exposures to 24,000 ft, 42% (N = 19, CI 23-67%) and 29% (N = 7, CI 5-70%) of the subjects varied between maximum EB scores < 3 and ≥ 3. The sample size needed to properly reject statistical significance of 1 EB step nominal difference between two paired exposures varied between 29-51 subjects.CONCLUSION: The large intraindividual test-retest variations in bubble grades during repeated hypobaric exposures highlight the need for relatively large numbers of subjects to reach statistical power when there are no or small differences in decompression stress between the exposures.Ånell R, Grönkvist M, Eiken O, Elia A, Gennser M. Intra-individual test-retest variation regarding venous gas bubble formation during high altitude exposures. Aerosp Med Hum Perform. 2022; 93(1):46-49.

Ten-year Spanish cohort of diving-related injuries in a non-hyperbaric tertiary hospital on the Spanish Mediterranean coast.

INTRODUCTION: Global evidence on the epidemiology of prevalent diving-related injuries (DRI) different from decompression sickness (DCS) and other fatalities is lacking. This study aimed to perform a comprehensive review of DRIs in the year-period between 2010-2020 in a non-hyperbaric tertiary hospital in the Spanish Mediterranean coast, in addition to identifying patient risk factors for severe middle ear barotrauma. METHODS: The study was conducted via a retrospective review of medical records during a 10-year period (2010-2020) at the University and Polytechnic Hospital La Fe (UPHLF) of Valencia. We performed a case-control study recruiting controls through an online survey to identify independent predictors for severe middle ear barotrauma. RESULTS: A total of 68 patients with DRI attended the emergency department of our tertiary referral hospital. Barotrauma accounted for more than 80% of DRI, followed by unrecognized DCS and animal-related injuries. Most patients required neither hospital admission nor surgery; appropriate treatment could be carried out largely on an outpatient basis. The presence of subsequent sequelae was minimal. Previous presence of significant ear, nose and throat (ENT) comorbidities (OR 3.05 - CI 95% 1.11 - 8.35), and older age (OR of younger age 0.94 - CI 95% 0.91 - 0.98) were identified as independent risk factors for severe middle ear barotrauma, with an acceptable discrimination capacity (AUC 0.793, 95% CI 0.71 - 0.87). CONCLUSION: The incidence of DRI may be higher than previously thought, and the need to know their epidemiology, their associated morbidity, and the deficiencies of the diving management system is becoming steadily important in order to develop prevention, diagnostic and therapeutic protocols in non-hyperbaric hospitals of these regions.

Whole-body vibration preconditioning reduces the formation and delays the manifestation of high-altitude-induced venous gas emboli.

NEW FINDINGS: What is the central question of this study? Is performing a 30-min whole-body vibration (WBV) prior to a continuous 90-min exposure at 24,000 ft sufficient to prevent venous gas emboli (VGE) formation? What is the main finding and its importance? WBV preconditioning significantly reduces the formation and delays the manifestation of high-altitude-induced VGE. This study suggests that WBV is an effective strategy in lowering decompression stress. ABSTRACT: Rapid decompression may give rise to formation of venous gas emboli (VGE) and resultantly, increase the risk of sustaining decompression sickness. Preconditioning aims at lowering the prevalence of VGE during decompression. The purpose of this study was to investigate the efficacy of whole-body vibration (WBV) preconditioning on high-altitude-induced VGE. Eight male subjects performed, on separate days in a randomised order, three preconditioning strategies: 40-min seated-rest (control), 30-min seated-rest followed by 150 knee-squats performed over a 10-min period (exercise) and 30-min WBV proceeded by a 10-min seated-rest. Thereafter, subjects were exposed to an altitude of 24,000 ft (7315 m) for 90 min whilst laying in a supine position and breathing 100% oxygen. VGE were assessed ultrasonically both during supine rest (5-min intervals) and after three fast, unloaded knee-bends (15-min intervals) and were scored using a 5-grade scale and evaluated using the Kisman Integrated Severity Score (KISS). There was a significant difference in VGE grade (P < 0.001), time to VGE manifestation (P = 0.014) and KISS score following knee-bends (P = 0.002) across protocols, with a trend in KISS score during supine rest (P = 0.070). WBV resulted in lower VGE grades (median (range), 1 (0-3)) and KISS score (2.69 ± 4.56 a.u.) compared with control (2 (1-3), P = 0.002; 12.86 ± 8.40 a.u., P = 0.011) and exercise (3 (2-4) , P < 0.001; 22.04 ± 13.45 a.u., P = 0.002). VGE were detected earlier during control (15 ± 14 min, P = 0.024) and exercise (17 ± 24 min, P = 0.032) than WBV (54 ± 38 min). Performing a 30-min WBV prior to a 90-min continuous exposure at 24,000 ft both delays the manifestation and reduces the formation of VGE compared with control and exercise preconditioning.

Effect of Long-Term Diving Exposure on Sleep of Male Occupational Divers in Southern Taiwan: A Cross-Sectional Study.

OBJECTIVE: Divers with a history of decompression sickness may be at high risk for sleep problems. However, limited studies have investigated the relationship between diving exposure and sleep problems of occupational divers. This study investigated the association between diving exposure and sleep quality and quantity among male occupational divers in southern Taiwan. METHODS: This descriptive, cross-sectional study included 52 occupational divers and 121 non-divers recruited from southern Taiwan in 2018. Survey data were collected using the Taiwanese version of the Hospital Anxiety and Depression Scale, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, and a self-report questionnaire that included demographic variables, diving exposure/protocols, and factors associated with sleep quality. RESULTS: Among all participants examined, occupational divers were significantly more likely to have both poor sleep quality (adjusted odds ratio [OR] = 3.00; 95% confidence interval [CI] = 1.48-6.06; P = 0.002) and excessive daytime sleepiness (adjusted OR = 4.49; 95% CI = 2.12-9.52; P < 0.001). The diving exposure time, depth, ascent rate, and decompression table use showed no significant associations between poor and good sleepers in the divers group. However, a history of decompression sickness was associated with poor sleep quality among divers (adjusted OR = 2.20; 95% CI = 1.07-4.54; P = 0.032). CONCLUSIONS: Our results showed that occupational divers had poor sleep quality and more excessive sleepiness than non-divers. Decompression sickness likely contributes to poor sleep quality. Prevention and early detection of decompression sickness-related sleep problems should be an occupational health priority.

Temporary and permanent unfitness of occupational divers. Brest Cohort 2002-2019 from the French National Network for Occupational Disease Vigilance and Prevention (RNV3P).

BACKGROUND: In France, the monitoring of professional divers is regulated. Several learned societies (French Occupational Medicine Society, French Hyperbaric Medicine Society and French Maritime Medicine Society) have issued follow-up recommendations for professional divers, including medical follow-up. Medical decisions could be temporary unfitness for diving, temporary fitness with monitoring, a restriction of fitness, or permanent unfitness. The aim of study was to point out the causes of unfitness in our centre. MATERIALS AND METHODS: The divers' files were selected from the French National Network for Occupational Disease Vigilance and Prevention (RNV3P). Only files with a special medical decision were selected, between 2002 and 2019. RESULTS: Three hundred and ninety-six professional divers are followed-up in our centre and 1371 medical decisions were delivered. There were 29 (7.3%) divers with a special medical decision, during 42 (3.1%) medical visit. Twelve (3.0%) had a permanent unfitness. The leading cause of unfitness was pulmonary diseases: emphysema (3), chronic obstructive pulmonary disorder (2), asthma (2). Sixteen (4.0%) divers had temporary unfitness. The leading causes were cardiovascular (4 times) and neurological (6 times). Twelve (3.0%) divers had had at least one decompression sickness. CONCLUSIONS: Judgments of permanent unfitness for diving were rare (3.0% of divers), but were because of life-threatening disease. Medical follow-up of occupational divers was justified to decrease the risk of fatal event during occupational dives.

Nitrogen Washout and Venous Gas Emboli During Sustained vs. Discontinuous High-Altitude Exposures.

INTRODUCTION: The frequency of long-duration, high-altitude missions with fighter aircraft is increasing, which may increase the incidence of decompression sickness (DCS). The aim of the present study was to compare decompression stress during simulated sustained high-altitude flying vs. high-altitude flying interrupted by periods of moderate or marked cabin pressure increase.METHODS: The level of venous gas emboli (VGE) was assessed from cardiac ultrasound images using the 5-degree Eftedal-Brubakk scale. Nitrogen washout/uptake was measured using a closed-circuit rebreather. Eight men were investigated in three conditions: one 80-min continuous exposure to a simulated cabin altitude of A) 24,000 ft, or four 20-min exposures to 24,000 ft interspersed by three 20-min intervals at B) 20,000 ft or C) 900 ft.RESULTS: A and B induced marked and persistent VGE, with peak bubble scores of [median (range)]: A: 2.5 (1-3); B: 3.5 (2-4). Peak VGE score was less in C [1.0 (1-2), P < 0.01]. Condition A exhibited an initially high and exponentially decaying rate of nitrogen washout. In C the washout rate was similar in each period at 24,000 ft, and the nitrogen uptake rate was similar during each 900-ft exposure. B exhibited nitrogen washout during each period at 24,000 ft and the initial period at 20,000 ft, but on average no washout or uptake during the last period at 20,000 ft.DISCUSSION: Intermittent reductions of cabin altitude from 24,000 to 20,000 ft do not appear to alleviate the DCS risk, presumably because the pressure increase is not sufficient to eliminate VGE. The nitrogen washout/uptake rate did not reflect DCS risk in the present exposures.Ånell R, Grönkvist M, Eiken O, Gennser M. Nitrogen washout and venous gas emboli during sustained vs. discontinuous high-altitude exposures. Aerosp Med Hum Perform. 2019; 90(6):524-530.

Health care worker decompression sickness: incidence, risk and mitigation.

Inadvertent exposure to radiation, chemical agents and biological factors are well recognized hazards associated with the health care delivery system. Less well appreciated yet no less harmful is risk of decompression sickness in those who accompany patients as inside attendants (IAs) during provision of hyperbaric oxygen therapy. Unlike the above hazards where avoidance is practiced, IA exposure to decompression sickness risk is unavoidable. While overall incidence is low, when calculated as number of cases over number of exposures or potential for a case during any given exposure, employee cumulative risk, defined here as number of cases over number of IAs, or risk that an IA may suffer a case, is not. Commonly, this unique occupational environmental injury responds favorably to therapeutic recompression and a period of recuperation. There are, however, permanent and career-ending consequences, and at least two nurses have succumbed to their decompression insults. The intent of this paper is to heighten awareness of hyperbaric attendant decompression sickness. It will serve as a review of reported cases and reconcile incidence against largely ignored individual worker risk. Mitigation strategies are summarized and an approach to more precisely identify risk factors that might prompt development of consensus screening standards is proposed.

Venous Gas Emboli and Ambulation at 4.3 psia.

INTRODUCTION: Ambulation during extravehicular activity on Mars may increase the risk of decompression sickness through enhanced bubble formation in the lower body. HYPOTHESES: walking effort (ambulation) before an exercise-enhanced denitrogenation (prebreathe) protocol at 14.7 psia does not increase the incidence of venous gas emboli (VGE) at 4.3 psia, but does increase incidence if performed after tissues become supersaturated with nitrogen at 4.3 psia. METHODS: VGE results from 45 control subjects who performed exercise prebreathe without ambulation before or during a 4-h exposure to 4.3 psia were compared to 21 subjects who performed the same prebreathe but ambulated before and during the hypobaric exposure (Group I) and to 41 subjects who only ambulated before the hypobaric exposure (Group II). Monitoring for VGE in the pulmonary artery was for 4 min at about 12-min intervals using precordial Doppler ultrasound (2.5 mHz). Detected VGE were assigned a categorical grade from I to IV. The detection of Grade III or IV was classified as "high VGE grade." RESULTS: The incidence of high VGE grade for Group I (57%) was greater than the control (17%) and Group II (15%). The incidence of pain-only decompression sickness was greater for Group I (20%) than the control (0%) and Group II (5%). CONCLUSIONS: High-grade VGE are increased by mild ambulation conducted under a supersaturated state (Group I vs. II); however, no increase was observed with mild ambulation during the saturated state alone (control vs. Group II).Conkin J, Pollock NW, Natoli MJ, Martina SD, Wessell JH III, Gernhardt ML. Venous gas emboli and ambulation at 4.3 psia. Aerosp Med Hum Perform. 2017; 88(4):370-376.

The demographics and diving behaviour of DAN Asia-Pacific members with and without pre-existing medical conditions.

INTRODUCTION: This report examines Diver Alert Network Asia-Pacific (DAN AP) members with and without cardiac or respiratory conditions, diabetes or hypertension and compares their demographics, health and diving activities. METHODOLOGY: Two online cross-sectional surveys of DAN AP members were conducted. The first sought information from 833 divers who applied for membership between July 2009 and August 2013 and who had declared the targeted medical conditions. The second, conducted between December 2014 and April 2015, was sent to 9,927 current members with known email addresses. The groups were compared for age, gender, body mass index, fitness, smoking and diving qualifications, history, currency and practices. RESULTS: Of 343 (41%) respondents to the first survey, 267 (32%) provided sufficient information for inclusion. Of 1,786 (18%) respondents to the second survey, 1,437 (15%) had no targeted medical condition and were included in the analysis. Those with medical conditions were on average 4.7 years older (P 〈 0.001); more overweight or obese (68% versus 57%, P = 0.001); took more medications (57% vs. 29%, P 〈 0.001), smoked less (4% vs. 7%, P = 0.02) and did less repetitive diving (median 75 vs 90, P 〈 0.001). Other diving demographics were similar. CONCLUSIONS: A substantial number of people are diving with medical conditions and there is a need to better understand the associated risks. Divers need to be well-educated about the potential impact such conditions may have on diving safety and should monitor their health status, especially as they age.

Can asthmatic subjects dive?

Recreational diving with self-contained underwater breathing apparatus (scuba) has grown in popularity. Asthma is a common disease with a similar prevalence in divers as in the general population. Due to theoretical concern about an increased risk for pulmonary barotrauma and decompression sickness in asthmatic divers, in the past the approach to asthmatic diver candidates was very conservative, with scuba disallowed. However, experience in the field and data in the current literature do not support this dogmatic approach. In this review the theoretical risk factors of diving with asthma, the epidemiological data and the recommended approach to the asthmatic diver candidate will be described.

Does self-certification reflect the cardiac health of UK sport divers?

BACKGROUND: Since 2009, the United Kingdom diving incident data show an increasing number of fatalities in the over-50s age group. Previous studies also suggest some divers take cardiac medications. Since 2001, diving medicals have not been mandatory for UK sport divers. Instead, an annual medical self-certification form, submitted to their club/school or training establishment, is required. We documented in a survey of UK sport divers the prevalence of cardiac events and medications and the frequency of medical certifications. METHODS: An anonymous on-line questionnaire was publicised. Measures included diver and diving demographics, prescribed medications, diagnosed hypertension, cardiac issues, events and procedures, other health issues, year of last diving medical, diagnosed persistent foramen ovale (PFO), smoking and alcohol habits, exercise and body mass index. RESULTS: Of 672 completed surveys, hypertension was reported by 119 (18%) with 25 of these (21%) having not had a diving medical. Myocardial infarction 6 (1%), coronary artery bypass grafting 3 (< 1%), atrial fibrillation 19 (3%) and angina 12 (2%) were also reported. PFOs were reported by 28 (4%), with 20 of these opting for a closure procedure. From 83 treated incidences of decompression illness (DCI), 19 divers reported that a PFO was diagnosed. CONCLUSIONS: Divers inevitably develop health problems. Some continue to dive with cardiac issues, failing to seek specialised diving advice or fully understand the role of the diving medical. Physicians without appropriate training in diving medicine may inform a diver they are safe to continue diving with their condition without appreciating the potential risks. The current procedure for medical screening for fitness to dive may not be adequate for all divers.

Simvastatin decreases incidence of decompression sickness in rats.

Decompression sickness (DCS) is a specific diving injury which sometimes may be life-threatening. Previous studies suggested that simvastatin (SIM) can protect against pathological inflammation and tissue damage. This study aimed to investigate whether SIM pretreatment could exert its beneficial effects on DCS. SIM was administered orally to adult male Sprague-Dawley rats for two weeks (2 mg/kg/day), then rats were subjected to a simulated dive at 700 kPa air pressure for 100 minutes before rapid decompression. After 30 minutes of symptom observation, lung tissue and blood samples were collected for further analysis. Compared to the vehicle-control, SIM pretreatment significantly decreased the incidence of DCS and ameliorated all parameters of pulmonary injuries, including lung dry/wet weight ratio, bronchoalveolar lavage fluid protein concentration, lung tissue malondialdehyde level and morphology. Moreover, SIM pretreatment abolished increases in systemic and pulmonary inflammation by reducing tumor necrosis factor-α levels in blood plasma and lung tissue. The results indicate that SIM may offer a novel pharmacological protection against injuries in DCS rats by inhibiting inflammatory responses. Further study is needed to understand the exact mechanisms.

A study on dysbaric osteonecrosis in caisson workers.

PURPOSE: To study the effects of exposure to compressed air on tunnel workers' health and to investigate the prevalence of dysbaric osteonecrosis (DON) in caisson workers. METHODS: 128 tunnel workers were divided into the exposed group (n = 58) and the control group (n = 70), and their shoulders, hips and knees were examined with X-ray, computed tomography (CT) and magnetic resonance imaging (MRI). RESULTS: 1) 34.5% of the exposed group were diagnosed with DON based on the national diagnostic criteria of decompression sickness. 2) The incidental difference of skeletal cystic changes between the exposed group and the control group was highly statistically significant (p < 0.01). 3) CT and MRI examination could detect early onset of DON lesions, and the cystic changes shown in CT and abnormal signals in MRI were diagnostic indicators in cases. CONCLUSION: Cystic changes in CT and abnormal signals in MRI are key imaging findings of early DON.

Time-dependent ROC analysis under diverse censoring patterns.

In biomedical studies, statistical approaches based on the Receiver Operating Characteristic (ROC) analysis have been extensively used in the evaluation of classification performance of markers and construction of classifiers. In this article, we investigate time-dependent ROC approaches for censored survival data. While most existing studies have been focused on uncensored and right-censored data, insufficient attention has been paid to other censoring schemes. This study advances from existing studies by investigating more diverse censoring schemes and developing ROC measurements under such censoring. Both estimation and inference are investigated. We conduct simulation and find satisfactory performance of the proposed approaches. We apply the proposed approaches to two real data sets, compare the prognostic power of markers, and investigate whether their linear combinations have better prognostic performance. We also explore graphical tools that can assist diagnostics and efficiently monitor the classification performance.

Decompression sickness risk at 6553 m breathing two gas mixtures.

INTRODUCTION: The risk of severe decompression sickness (DCS) increases rapidly above 6248 m (20,500 ft) and is greater when breathing higher proportions of inert gas. Contemporary aircrew may be exposed to higher cabin altitudes while breathing molecular sieve oxygen concentrator (MSOC) product gas containing variable concentrations of oxygen, nitrogen, and argon. This study assessed the risk of DCS at 6553 m (21,500 ft) breathing two simulated MSOC product gas mixtures. METHODS: In a hypobaric chamber, 10 subjects each undertook 2 4-h exposures at 6553 m breathing either 75% O2:21% N2:4% Ar or 56% 02:42% N2:2% Ar. Subjects undertook regular activities simulating in-flight movements of fast jet aircrew. Venous gas emboli (VGE) "bubble" load was graded every 15 min using 2D and Doppler echocardiography by experienced operators blinded to breathing gas composition. RESULTS: DCS occurred in five exposures (25%), the earliest after less than 90 min at altitude. All were minor, single-site, uncomplicated limb bends that resolved with recompression. VGE occurred in 85% of exposures with some early-onset, heavy loads. Survival (Probit) analysis indicated that breathing 56% oxygen significantly decreased VGE latency relative to breathing 75% oxygen (relative potency 3.05). CONCLUSIONS: From 20 experimental exposures, the risk of DCS at 6553 m is estimated at 5% by 90 min and 20% at 3 h. Exploiting the negative predictive value of VGE latency as a surrogate measure of protection from DCS, at high cabin altitudes better MSOC performance (higher product gas oxygen concentrations) will protect more aircrew for longer.

Acute and chronic gas bubble lesions in cetaceans stranded in the United Kingdom.

The first evidence suggestive of in vivo gas bubble formation in cetacea, including eight animals stranded in the UK, has recently been reported. This article presents the pathologic findings from these eight UK-stranded cetaceans and two additional UK-stranded cetacean cases in detail. Hepatic gas-filled cavitary lesions (0.2-6.0 cm diameter) involving approximately 5-90% of the liver volume were found in four (two juvenile, two adult) Risso's dolphins (Grampus griseus), three (two adult, one juvenile) common dolphins (Delphinus delphis), an adult Blainville's beaked whale (Mesoplodon densirostris), and an adult harbour porpoise (Phocoena phocoena). Histopathologic examination of the seven dolphin cases with gross liver cavities revealed variable degrees of pericavitary fibrosis, microscopic, intrahepatic, spherical, nonstaining cavities (typically 50-750 microm in diameter) consistent with gas emboli within distended portal vessels and sinusoids and associated with hepatic tissue compression, hemorrhages, fibrin/organizing thrombi, and foci of acute hepato-cellular necrosis. Two common dolphins also had multiple and bilateral gross renal cavities (2.0-9.0 mm diameter) that, microscopically, were consistent with acute (n = 2) and chronic (n = 1) arterial gas emboli-induced renal infarcts. Microscopic, bubblelike cavities were also found in mesenteric lymph node (n = 4), adrenal (n = 2), spleen (n = 2), pulmonary associated lymph node (n = 1), posterior cervical lymph node (n = 1), and thyroid (n = 1). No bacterial organisms were isolated from five of six cavitated livers and one of one cavitated kidneys. The etiology and pathogenesis of these lesions are not known, although a decompression-related mechanism involving embolism of intestinal gas or de novo gas bubble (emboli) development derived from tissues supersaturated with nitrogen is suspected.

Comparative data from 2250 male and female sports divers: diving patterns and decompression sickness.

BACKGROUND: The aim of the study was to compare the diving habits and histories of men and women in recreational scuba diving. METHODS: More than 10,000 questionnaires were circulated to recreational divers in the United Kingdom. Retrospective, broad-based information was requested concerning general health, smoking, alcohol, recreational drug use, diving habits and histories, and physician-confirmed and self-diagnosed episodes of decompression sickness (DCS). Data relating only to women were also gathered. Questionnaires were anonymous. RESULTS: Over four years, 2250 divers responded, 47% of whom were women. Of the 458,827 dives reported, 310% were by women. Differences in diving habits were observed between men and women, which included number of dives per annum, maximum depths dived, and dives with extra stops. When the level of experience was taken into account in this study group, the estimated rate of DCS in men was 2.60 times greater than for women. CONCLUSIONS: In this study, comparison between men and women in recreational diving differed from the initial evaluation when underlying factors were taken into account. Future studies should attempt to control for underlying factors in the data gathering and data analysis.

The incidence of venous gas emboli in recreational diving.

From 1989-91, the Divers Alert Network monitored recreational divers for Doppler-detected venous gas emboli (VGE) and depth-time profiles following multi-day, repetitive, multi-level exposures. A Spencer score >0 occurred in 61 of 67 subjects (91%) and 205 of 281 dives (73%). No subject developed decompression sickness (DCS) on monitored days although 102 dives (36.3%) scored at Spencer Grades 2 or 3 (High Bubble Grade, HBG). We recorded the depth-time profiles with Suunto dive computers and estimated exposure severity with a probabilistic decompression algorithm. The HBG incidence increased 53% over the range of exposure severity (p < 0.001) in the divers, was approximately 20% higher for repetitive dives than for first dives, and decreased approximately 25% over the 6-8 days of multi-day diving (p < 0.001) suggesting a phenomenon similar to DCS adaptation. The observed HBG incidence was approximately 20% higher for males than females. Older male divers had a 25% increase in observed incidence of HBG while older female divers showed a 55% increase when compared to their younger counterparts.

Diving methods and decompression sickness incidence of Miskito Indian underwater harvesters.

Diving conditions, dive profiles, and symptoms of decompression sickness (DCS) in a group of Miskito Indian underwater seafood harvesters are described. Dive profiles for 5 divers were recorded with dive computers, and DCS symptoms were assessed by neurological examination and interview. Divers averaged 10 dives a day over a 7-day period with a mean depth of 67 +/- 7 FSW (306 +/- 123 kPa) and average in-water time of 20.6 +/- 6.3 minutes. Limb pain was reported on 10 occasions during 35 man-days of diving. Symptoms were typically managed with analgesic medication rather than recompression. Indices of the decompression stress were estimated from the recorded profiles using a probabilistic model. We conclude that the dives were outside the limits of standard air decompression tables and that DCS symptoms were common. The high frequency of limb pain suggests the potential for dysbaric bone necrosis for these divers.