Decompression Sickness

This cross-sectional online survey study assesses health status, physical fitness, and safety knowledge as potential determinants of diving-related adverse events among recreational divers in Poland. Recreational diving exposes participants to specific hazards, including decompression sickness (DCS) and barotrauma of the middle ear, sinuses, and lungs. To date, no Polish study has simultaneously evaluated health, physical fitness, theoretical safety knowledge, and the occurrence of adverse events in this population. Adult divers (18 years or older) who completed at least one dive in the past 24 months and reside in Poland complete an anonymous online questionnaire (about 12 to 18 minutes). Physical fitness is estimated as VO2max using the University of Houston Non-Exercise Test (physical activity rating, age, BMI, and sex). Knowledge of DCS, barotrauma, and safe-diving rules is tested at three difficulty levels. The questionnaire also captures diving exposure, certification level, chronic health conditions, and risky behaviours (smoking, alcohol use, and diving beyond certification). The primary endpoint is the proportion of divers reporting at least one diving-related adverse event. Associations with certification level, estimated VO2max, BMI, and other factors are analysed using multivariable logistic regression. The study is non-interventional, anonymous, and carries minimal risk; no clinical procedures or biological sampling are involved.

This study evaluates oxygen prebreathe protocols and exercise conditions to reduce risk of decompression sickness during simulated extravehicular activity. Healthy adult volunteers will undergo oxygen prebreathe followed by hypobaric chamber exposure with monitoring for symptoms and ultrasound detection of bubbles.

This retrospective study aims at an epidemiological description of the clinical presentation of medical problems in technical diving. It assess anthropometric data, diving experience and dive planification, clinical presentation, treatment received and pronostic to understand specificity of this community.

Inner Ear Decompression sickness (IEDS) accounts for 20% of all types of decompression sickness (the bends) in divers. The condition commonly affects the peripheral vestibular system (inner ear). IEDS results in acute symptoms of dizzyness (vertigo) and imbalance. Even with the recommended treatment of hyperbaric oxygen therapy some people do not recovery fully. However, even in the presence of a permanent vestibular deficit many people can show a behavioural recovery where symptoms improve over time. Recovery can be aided by vestibular rehabilitation (VR) which is now routine for acute IEDS but was not provided before 2021, and is not widespread across the UK (United Kingdom) or world, meaning people may have a suboptimal recovery. This project will investigate if and how people recover after an acute episode of IEDS and whether people who had IEDS in the past show changes in the central (brain) processing of vestibular function and in symptoms of dizziness, balance and posture. This project has two main parts. Part one is a prospective observational study where people with an acute onset of IEDS are serially monitored while they are receiving hyperbaric treatment and VR over 10-14 days. Part two is a retrospective observational study where who have had IEDS in the past 15 years are re-assessed in a one-off session. The tests in both parts involve clinical tests and specialist eye movement recordings that assess vestibular function. We will also determine the site of any vestibular pathology by using selective stimulation of the vestibular end organ or nerve and assess whether there are any changes in how the structure and function of central vestibular pathways in the brain. In people with chronic IEDS with vestibular symptoms we will offer participants a course of VR over 12 weeks and assess whether this is associated with any improvement in symptoms.

The impact of oxygen therapy in many pathologies has been subject of recent work, arguing both favourable and harmful effects. Consequently, one can wonder about the influence of hyperoxic gas mixture during diving on the genesis of decompression sickness, but also about the systematic application of normobaric and hyperbaric oxygen in case of proven decompression sickness. In mammals, normoxic concentrations have been redefined at 20-100 mbars at the extracellular level and below 10 mbars in the mitochondria. Under hyperbaric conditions, most of the oxygen being dissolved in blood plasma, a state of hyperoxia is established which escapes the usual delivery and regulation system represented by red blood cells. The results of our team's previous work suggest a specific effect of diving on the levels of circulating mitochondrial DNA (mtDNA), suggesting cellular destruction linked to hyperoxia/hyperbaria. In fact, our studies, carried out on both animals and human divers, have shown that diving accident leads to an increase in mtDNA levels and an immune reaction through the mobilisation of leukocytes. The main objective of this study is to compare the influence of oxygen partial pressure levels on the evolution of clinical and biological variables during hyperbaric oxygen therapy sessions in healthy versus injured divers.