Modelling the risk factors for accidents in recreational divers: results from a cross-sectional evaluation in Belgium.

Introduction: Characterisation of the recreational diving community could help to identify scuba divers at risk for accidents.

Methods: We performed a cross-sectional evaluation in a federation for recreational scuba divers in Belgium (Duiken.Vlaanderen).

Physiology of deep closed circuit rebreather mixed gas diving: vascular gas emboli and biological changes during a week-long liveaboard safari.

Diving decompression theory hypothesizes inflammatory processes as a source of micronuclei which could increase related risks. Therefore, we tested 10 healthy, male divers. They performed 6-8 dives with a maximum of two dives per day at depths ranging from 21 to 122 msw with CCR mixed gas diving.

Selecting optimal air diving gradient factors for Belgian military divers: more conservative settings are not necessarily safer.

Introduction: In 2018, the Belgian Defence introduced a commercial off-the-shelf dive computer (Shearwater Perdix™) for use by its military divers. There were operational constraints when using its default gradient factors (GF). We aimed to provide guidelines for optimal GF selection.

Mini Trampoline, a New and Promising Way of SCUBA Diving Preconditioning to Reduce Vascular Gas Emboli?

Despite evolution in decompression algorithms, decompression illness is still an issue nowadays. Reducing vascular gas emboli (VGE) production or preserving endothelial function by other means such as diving preconditioning is of great interest. Several methods have been tried, either mechanical, cardiovascular, desaturation aimed or biochemical, with encouraging results.

Physiology of repeated mixed gas 100-m wreck dives using a closed-circuit rebreather: a field bubble study.

Purpose: Data regarding decompression stress after deep closed-circuit rebreather (CCR) dives are scarce. This study aimed to monitor technical divers during a wreck diving expedition and provide an insight in venous gas emboli (VGE) dynamics.

Methods: Diving practices of ten technical divers were observed.

Increased Risk of Decompression Sickness When Diving With a Right-to-Left Shunt: Results of a Prospective Single-Blinded Observational Study (The "Carotid Doppler" Study).

Divers with a patent Foramen Ovale (PFO) have an increased risk for decompression sickness (DCS) when diving with compressed breathing gas. The relative risk increase, however, is difficult to establish as the PFO status of divers is usually only determined after a DCS occurrence. This prospective, single-blinded, observational study was designed to collect DCS data from volunteer divers after screening for right-to-left shunt (RLS) using a Carotid Doppler test.

Comparison of insulation provided by dry or wetsuits among recreational divers during cold water immersion (< 5°C).

Background: Divers thermal status influences susceptibility to decompression sickness hence the need for proper insulation during immersion in cold water. However, there is a lack of data on thermal protection provided by diving suits, hence this study.

Materials And Methods: Two different groups of divers wearing either a wetsuit (n = 15) or a dry suit (n = 15) volunteered for this study.

Hypoxic and Hyperoxic Breathing as a Complement to Low-Intensity Physical Exercise Programs: A Proof-of-Principle Study.

Inflammation is an adaptive response to both external and internal stimuli including infection, trauma, surgery, ischemia-reperfusion, or malignancy. A number of studies indicate that physical activity is an effective means of reducing acute systemic and low-level inflammation occurring in different pathological conditions and in the recovery phase after disease. As a proof-of-principle, we hypothesized that low-intensity workout performed under modified oxygen supply would elicit a "metabolic exercise" inducing a hormetic response, increasing the metabolic load and oxidative stress with the same overall effect expected after a higher intensity or charge exercise.

Heart Rate Variability During a Standard Dive: A Role for Inspired Oxygen Pressure?

Heart rate variability (HRV) during underwater diving has been infrequently investigated because of environment limitations and technical challenges. This study aims to analyze HRV changes while diving at variable hyperoxia when using open circuit (OC) air diving apparatus or at constant hyperoxia using a closed-circuit rebreather (CCR). We used HRV analysis in time and frequency domain adding nonlinear analysis which is more adapted to short-time analysis and less dependent on respiratory rate (Sinus respiratory arrhythmia).

First impressions: Use of the Azoth Systems O'Dive subclavian bubble monitor on a liveaboard dive vessel.

Introduction: The Azoth Systems O'Dive bubble monitor is marketed at recreational and professional divers as a tool to improve personal diving decompression safety. We report the use of this tool during a 12-day dive trip aboard a liveaboard vessel.

Methods: Six divers were consistently monitored according to the user manual of the O'Dive system.

Recurrence of spontaneous pneumothorax six years after VATS pleurectomy: evidence for formation of neopleura.

Background: Primary Spontaneous Pneumothorax (PSP) is considered an absolute and definitive contraindication for scuba diving and professional flying, unless bilateral surgical pleurectomy is performed. Only then is there a sufficiently low risk of recurrence to allow a waiver for flying and/or diving.

Case Presentation: A young fit male patient who suffered a PSP 6 years ago, and underwent an uncomplicated videoscopic surgical pleurectomy, presented with a complete collapse of the lung on the initial PSP side.

Evaluation of Protection Level, Respiratory Safety, and Practical Aspects of Commercially Available Snorkel Masks as Personal Protection Devices Against Aerosolized Contaminants and SARS-CoV2.

: The "Severe Acute Respiratory Syndrome Coronavirus 2″ (SARS-CoV2) pandemic has led to a worldwide shortage of personal protection devices (PPD) for medical and paramedical personnel. Adaptation of commercially available snorkel masks to serve as full face masks has been proposed. Even not formally approved as PPD, they are publicized on social media as suitable for this use.

Percutaneous closure of patent foramen ovale for the secondary prevention of decompression illness in sports divers: mind the gap.

Objective: To evaluate the efficiency of percutaneous patent foramen ovale (PFO) closure on the recurrence of decompression illness (DCI).

Design: Retrospective, observational study with interview and questionnaire.

Setting: Tertiary referral center.

Static Metabolic Bubbles as Precursors of Vascular Gas Emboli During Divers' Decompression: A Hypothesis Explaining Bubbling Variability.

Introduction: The risk for decompression sickness (DCS) after hyperbaric exposures (such as SCUBA diving) has been linked to the presence and quantity of vascular gas emboli (VGE) after surfacing from the dive. These VGE can be semi-quantified by ultrasound Doppler and quantified via precordial echocardiography. However, for an identical dive, VGE monitoring of divers shows variations related to individual susceptibility, and, for a same diver, dive-to-dive variations which may be influenced by pre-dive pre-conditioning.

Early detection of diving-related cognitive impairment of different nitrogen-oxygen gas mixtures using critical flicker fusion frequency.

Introduction: Cognitive impairment related to inert gas narcosis (IGN) is a threat to diving safety and operations at depth that might be reduced by using enriched air nitrox (EANx) mixtures. Using critical flicker fusion frequency (CFFF), a possible early detection of cognitive abilities/cerebral arousal impairment when breathing different oxygen (O2) fractions was investigated.

Methods: Eight male volunteers performed, in random order, two dry chamber dives breathing either air or EANx40 (40% O₂-60% nitrogen) for 20 minutes (min) at 0.

Critical Flicker Fusion Frequency: A Marker of Cerebral Arousal During Modified Gravitational Conditions Related to Parabolic Flights.

evaluation of human brain performance and arousal remains challenging during operational circumstances, hence the need for a rapid, reliable and reproducible tool. Here we hypothesized that the Critical flicker fusion frequency (CFFF) reflecting/requiring visual integration, visuo-motor skills and decision-taking process might be a powerful, fast and simple tool in modified gravity environments. Therefore 11 male healthy volunteers were assessed for higher cognitive functions with CFFF during parabolic flights.

Variability in circulating gas emboli after a same scuba diving exposure.

Purpose: A reduction in ambient pressure or decompression from scuba diving can result in ultrasound-detectable venous gas emboli (VGE). These environmental exposures carry a risk of decompression sickness (DCS) which is mitigated by adherence to decompression schedules; however, bubbles are routinely observed for dives well within these limits and significant inter-personal variability in DCS risk exists. Here, we assess the variability and evolution of VGE for 2 h post-dive using echocardiography, following a standardized pool dive in calm warm conditions.

Patent Foramen Ovale (PFO), Personality Traits, and Iterative Decompression Sickness. Retrospective Analysis of 209 Cases.

There is a need to evaluate the influence of risk factors such as patency of foramen ovale (PFO) or "daredevil" psychological profile on contra-indication policy after a decompression sickness (DCS). By crossing information obtained from Belgian Hyperbaric Centers, DAN Emergency Hotline, the press, and Internet diving forums, it was possible to be accountable for the majority if not all DCS, which have occurred in Belgium from January 1993 to June 2013. From the available 594 records we excluded all cases with tentative diagnosis, medullary DCS or unreliability of reported dive profile, leaving 209 divers records with cerebral DCS for analysis.

Do Environmental Conditions Contribute to Narcosis Onset and Symptom Severity?

Although many factors contributing to inert gas narcosis onset and severity have been put forward, the available evidence is not particularly strong. Using objective criteria, we have assessed brain impairment associated with narcosis under various environmental diving conditions. 40 volunteers performed a no-decompression dive (33 m for 20 min) either in a dry chamber, a pool or open sea.

Poorly designed research does not help clarify the role of hyperbaric oxygen in the treatment of chronic diabetic foot ulcers.

Diabetic foot ulcers (DFUs) are one of the most common indications for hyperbaric oxygen treatment (HBOT). The role of HBOT in DFUs is often debated. Recent evidence based guidelines, while recommending its use, urge further studies to identify the patient subgroups most likely to benefit from HBOT.

Cutis Marmorata skin decompression sickness is a manifestation of brainstem bubble embolization, not of local skin bubbles.

"Cutis Marmorata" skin symptoms after diving, most frequently in the form of an itching or painful cutaneous red-bluish discoloration are commonly regarded as a mild form of decompression sickness (DCS), and treated with oxygen inhalation without reverting to hyperbaric recompression treatment. It has been observed that the occurrence of Cutis Marmorata is frequently associated with the presence of a Patent Foramen Ovale (PFO) of the heart, and indeed, with a properly executed contrast echocardiographic technique, these patients have an almost 100% prevalence of PFO. Only occasionally, Cutis Marmorata is accompanied by other symptoms of DCS.

Persistent (patent) foramen ovale (PFO): implications for safe diving.

Diving medicine is a peculiar specialty. There are physicians and scientists from a wide variety of disciplines with an interest in diving and who all practice 'diving medicine': the study of the complex whole-body physiological changes and interactions upon immersion and emersion. To understand these, the science of physics and molecular gas and fluid movements comes into play.

Association of microparticles and neutrophil activation with decompression sickness.

Decompression sickness (DCS) is a systemic disorder, assumed due to gas bubbles, but additional factors are likely to play a role. Circulating microparticles (MPs)--vesicular structures with diameters of 0.1-1.

The use of portable 2D echocardiography and 'frame-based' bubble counting as a tool to evaluate diving decompression stress.

Introduction: 'Decompression stress' is commonly evaluated by scoring circulating bubble numbers post dive using Doppler or cardiac echography. This information may be used to develop safer decompression algorithms, assuming that the lower the numbers of venous gas emboli (VGE) observed post dive, the lower the statistical risk of decompression sickness (DCS). Current echocardiographic evaluation of VGE, using the Eftedal and Brubakk method, has some disadvantages as it is less well suited for large-scale evaluation of recreational diving profiles.

Bubble stream reveals functionality of the right-to-left shunt: detection of a potential source for air embolism.

The existence of a right-to-left shunt may increase the likelihood of micro-embolism by allowing a flux of bubbles under hyperbaric conditions. The aim of the study was to measure the relationship between these shunts and bubbles in 10 consecutive subjects using trans-thoracic and trans-esophageal echocardiography. In video frames, all cardiac chambers were segmented and bubbles were analyzed by our proposed method and two other methods.