Effects of hyperbaric exposure on mechanical and electronic parameters of implantable cardioverter-defibrillators.

AIMS: Hyperbaric oxygen therapy (HBOT) is the standard adjuvant treatment for life-threatening or disabling pathologies. Currently, mechanical and electronic variations of implantable cardioverter-defibrillators (ICD) in hyperbaric conditions have not been evaluated. As a result, many patients eligible for HBOT but ICD recipients cannot undergo this therapy, even in emergency situations. METHODS AND RESULTS: Twenty-two explanted ICD of various brands and models were randomized in two groups: single hyperbaric exposure at an absolute pressure of 4000 hPa and 30 iterative hyperbaric exposures at an absolute pressure of 4000 hPa. Mechanical and electronic parameters of these ICD were blindly assessed before, during, and after hyperbaric exposures. Regardless of the hyperbaric exposure, we could not find any mechanical distortion, inappropriate occurrence of anti-tachycardia therapies, dysfunction of tachyarrhythmia therapeutic programming, or dysfunction of programmed pacing parameters. CONCLUSION: Dry hyperbaric exposure seems harmless on ICD tested ex vivo. This result may lead to a reconsideration of the absolute contraindication of emergency HBOT to ICD recipients. A real-life study in these patients with an indication to HBOT should be performed to assess their tolerance to the treatment.

Risk factors for immersion pulmonary edema in recreational scuba divers: a case-control study.

BACKGROUND: Immersion can cause immersion pulmonary edema (IPE) in previously healthy subjects. We performed a case-control study to better identify IPE risk factors. METHODS: We prospectively included recreational scuba divers who had presented signs of IPE and control divers who were randomly chosen among diving members of the French Underwater Federation. We sent an anonymous questionnaire to each diver, with questions on individual characteristics, as well as the conditions of the most recent dive (controls) or the dive during which IPE occurred. Univariate logistic regressions were performed for each relevant factor. Then, multivariate logistic regression was performed. RESULTS: Of the 882 questionnaires sent, 480 (54%) were returned from 88 cases (90%) and 392 control divers (50%). Multivariate analysis identified the following independent risk factors associated with IPE: being aged over 50 years ((OR) 3.30, (95%CI) 1.76-6.19); female sex (OR 2.20, 95%CI 1.19-4.08); non-steroidal anti-inflammatory drug (NSAID) intake before diving (OR 24.32, 95%CI 2.86-206.91); depth of dive over 20 m (OR 2.00, 95%CI 1.07-3.74); physical exertion prior to or during the dive (OR 5.51, 95%CI 2.69-11.28); training dive type (OR 5.34, 95%CI 2.62-10.86); and daily medication intake (OR 2.79, 95%CI 1.50-5.21); this latter factor appeared to be associated with hypertension in the univariate analysis. CONCLUSION: To reduce the risk of experiencing IPE, divers over 50 years of age or with hypertension, especially women, should avoid extensive physical effort, psychological stress, deep dives and NSAID intake before diving.

Venous gas emboli are involved in post-dive macro, but not microvascular dysfunction.

PURPOSE: Previous studies have shown vascular dysfunction of main conductance arteries and microvessels after diving. We aim to evaluate the impact of bubble formation on vascular function and haemostasis. To achieve this, we used a vibration preconditioning to influence bubble levels without changing any other parameters linked to the dive. METHODS: Twentty-six divers were randomly assigned to one of three groups: (1) the "vibrations-dive" group (VD; n = 9) was exposed to a whole-body vibration session 30 min prior the dive; (2) the "diving" group (D; n = 9) served as a control for the effect of the diving protocol; (3) The "vibration" protocol (V; n = 8) allowed us to assess the effect of vibrations without diving. Macro- and microvascular function was assessed for each subject before and after the dive, subsequently. Bubble grades were monitored with Doppler according to the Spencer grading system. Blood was taken before and after the protocol to assess any change of platelets or endothelial function. RESULTS: Bubble formation was lower in the VD than the diving group. The other measured parameters remained unchanged after the "vibration" protocol alone. Diving alone induced macrovascular dysfunction, and increased PMP and thrombin generation. Those parameters were no longer changed in the VD group. Conversely, a microvascular dysfunction persists despite a significant decrease of circulating bubbles. CONCLUSIONS: Finally, the results of this study suggest that macro- but not microvascular impairment results at least partly from bubbles, possibly related to platelet activation and generation of pro-coagulant microparticles.

Occupational accidents among attendants inside hyperbaric chambers in France.

INTRODUCTION: The purpose of the study was to assess the number of accidents among staff employed in the operation of hyperbaric chambers in France. MATERIALS AND METHODS: A retrospective study using a questionnaire was carried out on occupational accidents in France between 2005 and 2011. RESULTS: 12 (46%) centres participated in the study, representing 73 subjects. The mean age was 43.5 years (SD=9.73). They had worked in hyperbaric chambers for 9.8 years on average (SD=7.7). The average number of hyperbaric sessions was 198.3 per subject (SD=174.25), for a total of 8.072 hyperbaric sessions; 27% of the subjects reported that they had at least one accident during the study period. In all, 30 accidents were reported: 3 blood exposures, 4 accidents related to patient handling, 20 hyperbaric accidents; 3 other accidents. Of the hyperbaric accidents, 2 (10%) involved decompression sicknesses with cutaneous symptoms, 3 (15%) decompression illness (DCI), 14 (70%) ear traumatisms, 1 (5%) dental accident. The incidences were 372 per 100,000 sessions in hyperbaric chambers (SHC) for all accidents, 248 per 100,000 SHC for hyperbaric accidents and 173 per 100,000 SHC for ENT barotraumas. CONCLUSION: The accidents involving staff operating hyperbaric chambers were mainly ear traumatisms..

Intracerebral hemorrhage related to systemic gas embolism during hysteroscopy.

Iatrogenic gas embolism is a rare but serious problem that has been documented in almost all medical specialties including gynecology. We present a 49-year-old woman undergoing operative hysteroscopy and myomectomy, who sustained sudden hypotension and decrease in the end-tidal carbon dioxid levels during the procedure. Systemic gas embolism was confirmed by echocardiographic evidence of bubbles in both right and left cardiac cavities and a rise of troponin. Hyperbaric oxygen was rapidly administered in addition to maintenance of vital functions and anti-thrombotic prevention with calciparin. A right hemiparesis was apparent after recovery from general anesthesia. Brain-computed tomography and magnetic resonnance imaging, performed on Days 3 and 2 respectively, showed a left fronto-parietal hematoma surrounded by edema. Having ruled out risk factors for a primary ischemic or hemorrhagic stroke, we concluded that hemorragic transformation of the ischemic cerebral lesion caused by gas embolism was responsible for the observed intraparenchymal hematoma. As far as we know, this is the first report relating cerebral gas embolism with an intracerebral hemorrhage. It provides an argument against anticoagulant therapy during the early stages of gas embolism care.

Evolution of the respiratory function of professional divers over 15 years.

BACKGROUND: The study was aimed at assessing changes in respiratory function after 15 years of profes- sional diving, among scientific divers. MATERIALS AND METHODS: A retrospective study was performed on divers who underwent an initial visit and a visit 15 years later at the same medical centre, among divers who had a scientific activity (monitoring the coastline, fauna and flora). Pulmonary function tests were performed in the same laboratory with the same operating standards and using a Jaeger MasterBody plethysmograph. Each subject acted as his or her own control. The data were analysed by Student's t-test and Spearman's correlation coefficient. RESULTS: Twenty-six divers were included. Changes over 15 years included: a decrease in the forced expired volume in 1 second/functional vital capacity (FEV1/FVC) ratio (-6 for absolute value, p < 0.01; and -5% for theoretical value, p = 0.02); a decrease in forced expiratory flow (FEF)25% (-1.1 for absolute value, p < 0.01; and -21% for theoretical value, p < 0.01); a decrease in transfer factor for carbon monoxide (TLCO) (-0.7 for absolute value, p = 0.04); and an increase in vital capacity (VC) (+8% for theoretical value, p = 0.03). A significant correlation was found between the consumption of tobacco in packs per year (PY) and the variations in VC (r = 0.89; p < 0.01) and the variations in the theoretical FEV1 (r = 0.76; p = 0.03). There was a significant relationship between the number of dives and the variations in the percentage of the theoretical FEV1/FVC ratio (r = -0.42; p = 0.04). The same relationship was found for the average of dive duration (r = -0.59; p < 0.01) Conclusions: With increasing length of diving activities service, the pulmonary function displays a trend toward both a decrease in TLCO and a decrease in FEF25%.

Health effects of hyperbaric exposure on chamber attendants: a literature review.

BACKGROUND: Inside attendants working in hyperbaric chambers are exposed to risks related to the hyperbaric environment, handling and care. The aim of this study is to review the literature focusing on the impact of this activity on health. MATERIALS AND METHODS: This is a literature review using the Medline database. RESULTS: Eight articles studied decompression illness (DCI). The incidence of DCI ranged from 0 to 37 per 100,000 sessions in hyperbaric chambers (SHC). The incidence of injuries ranged from 0 to 412 per 100,000 SHC. The most prevalent cause of accidental death was fire: 77 deaths (patients and attendants) between 1923 and 1996. Dysbaric osteonecrosis has been reported in one study only. CONCLUSIONS: Inside attendants face risks in the chamber, even if serious health effects seems rare compared to the total number of SHC.

Infectious diseases affecting occupational divers: review of 2017 literature.

BACKGROUND: Occupational divers are prone to many health risks. For instance, they can get infections. We reviewed the infectious diseases in occupational divers. MATERIALS AND METHODS: This is a literature review which went on up to 31.12.2017. The research was carried out on Medline and Scopus databases, in French and English languages. RESULTS: Fifteen papers report cases of infections in occupational divers. They are mainly skin infections, but also ear-nose-throat and ophthalmological infections. DISCUSSION AND CONCLUSIONS: According to data collected, infections among occupational divers are quite scarce. These diseases are not specific to the workplace, and are comparable with data on recreational diving. Prevention is mainly based on hygiene and equipment maintenance.

Can a transgender person be an occupational diver? Demonstration from a case report.

This is the first case report about a transgender professional diver. The purpose of this article is to show the professional adaptations to help him to continue occupational dive and to raise the question of the impact on diving risks of hormonal treatment in this case. He was a 39-year-old man when he began his transition. He had worked as a diver for 9 years before his transition. When he changed to look like a woman, there were a few difficulties in continuing his professional activity. The main difficulty was that he looked like a woman while working with men. Modesty was a crucial issue in the enterprise. There were other problems such as the organisation of premises, the physical workload and the interaction between treatments and diving. There is a lack of a law to guide the employer. French legislation does not address the issue of transsexuals for this profession. The medical recommendations do not specify contraindications or adaptations for diving safely. Because of his transition, he lost muscle mass. The occupational physician helped to adjust his activity: decreasing the weight of his diving suit, creating a female-like locker room etc. Finally, the question of the risk of decompression illness arose. Legal hormonal medication seems not to significantly increase the risk of decompression illness, but this diver was taking illicit treatment to speed up the transition. The occupational physician recommended taking the legal hormonal medication.

Longitudinal change in professional divers' lung function: literature review.

BACKGROUND: The aim of this study was to assess changes in lung function of professional divers. MATERIALS AND METHODS: This is a review of the literature. Only studies about professional divers were included. All published studies between 01.01.1984 and 07.01.2014 were systematically searched. The search was performed in Medline and Embase databases and in the "Medicina Maritima" journal. The results of pulmonary function tests were extracted from each study. RESULTS: Fifteen articles were found. Four studies showed a significant decrease in forced vital capacity (FVC). Five studies demonstrated a significant decrease in forced expiratory flows (FEF) at 75% and 50% of FVC expired (FEF75% and FEF50%) after 3 years of diving. Seven studies demonstrated a significant decrease in forced expiratory volume in 1 second (FEV1) after 3 years of diving. But only 2 studies did an age-standardisation so that only 1 study demonstrated a significant decrease in FEV1 after age-standardisation. Three articles showed a decrease in transfer factor for carbon monoxide (TLCO) after 5 years. Dives parameters (like depth, number by year) were not always related to variations on the different lung variables. CONCLUSIONS: This literature review showed a decrease in TLCO, FEF75% and FEF25-75%. One wonders whether these variations are due to the age or to diving. The results of such a long-term study would be interesting and might help to guide fundamental research.

Reversible myocardial dysfunction and clinical outcome in scuba divers with immersion pulmonary edema.

Immersion pulmonary edema in scuba divers is a rare disorder that tends to recur and can be potentially fatal, even in the absence of underlying cardiac disease. Anecdotal cases of reversible myocardial dysfunction have been described in this setting, but little is known of its pathogenesis. The purpose of the present study was to determine the clinical outcomes and the determinants associated with this condition. The data from 54 consecutive divers admitted for acute immersion pulmonary edema during a 5.5-year period were retrospectively studied. A diagnosis of myocardial dysfunction was established by the presence of elevated cardiac troponin T levels, coupled with electrocardiographic changes and/or wall motion abnormalities on the echocardiogram. The demographic, clinical, biologic, and diving characteristics were tested as potential predictors of this disorder. All the patients had complete resolution of symptoms within 72 hours, but 3 required intensive ventilation or hemodynamic support at admission. Reversible myocardial dysfunction was observed in 28% and was associated more with age >50 years (odds ratio [OR] 5.5, 95% confidence interval [CI] 1.5 to 21, p = 0.013), hypertension (OR 8.2, 95% CI 2.1 to 32, p = 0.002), diabetes (OR 22.1, 95% CI 1.1 to 458; p = 0.002), and release of natriuretic peptides (OR 9.1, 95% CI 2.4 to 35, p = 0.001). Follow-up investigations at 1 month were obtained for 49 patients and revealed a significant number of patients with occult hypertension. In conclusion, reversible myocardial dysfunction is not uncommon in divers with immersion pulmonary edema. The short-term overall prognosis is not adversely altered, but severe heart failure with a fatal outcome is unpredictable. Close monitoring of older divers with latent cardiovascular risk factors is warranted.

Cardiovascular risk factors and cardiovascular risk assessment in professional divers.

BACKGROUND: The professional diver's activity implies body cardiovascular stress. Little data on cardiovascular risk factors is available. Some studies report a high prevalence of tobacco consumption. The purpose of this study is to investigate the cardiovascular risk factors of professional divers and calculate the predicted 5-year risk and the predicted 10-year risk of an acute coronary event. MATERIALS AND METHODS: In one medical centre, data on dives and cardiovascular risk factors were analysed on Epidata(®) software, by Pearson χ(2) test or by Fisher's exact test, by analysis of variance test or by Kruskal-Wallis test, and by Spearman correlation coefficient. Cardiovascular risk scores at 5 and 10 years were calculated using SCORE. RESULTS: A total 200 professional divers were included. Of these, 31% were smokers or had stopped smoking for less than 3 years; 40% had an abnormal body mass index; 50% had raised total cholesterol levels; 11% had an advanced age; 6.5% had high blood pressure; 81% had at least one risk factor; 66% had an alterable risk factor; 25.5% had a 5-year risk greater than that of the general population of the same age; 2.5% had a high cardiovascular risk at 10 years; and 34% were at intermediate risk. CONCLUSIONS: The majority of divers had at least one cardiovascular risk factor. Cardiovascular risk scores were lower than that of the general population. However, some of this population is at high risk. One third of the divers had an intermediate risk, which should lead to the consideration of conducting additional biological examinations to better assess their risk.