Self-contained Underwater Breathing Apparatus Research Articles

Exploring the Locker

This article is an effort to foster grace and to create genuine, humble community. A new sense of community, that is not conditional on our abilities to censor ourselves to be more palatable to those around us. Instead, the birth of a new way of relating that considers our deep inner selves that feel shame, remember traumas, and cower in fear of these experiences. Perhaps most of all, this article is an invitation to explore our deepest inner selves, and the cost of censoring this self. This exploration is not a leisurely dive into the corners of ourselves that lie in the shallows. It is an adventure that will require a full set of SCUBA gear, and a courageous spirit. A courageous spirit that is not only willing to dig through the shame, fear, and anger that covers our raw selves, but a spirit that will then sit with these wounded and forgotten parts, and begin to build a new sense of balance.

Effects of SCUBA bubbles on counts of roving piscivores in a large remote marine protected area.

This study examined the effects of SCUBA bubbles on fish counts in underwater visual surveys conducted in the Papahānaumokuākea Marine National Monument (PMNM). Specifically, paired fish surveys were conducted at each survey site, utilizing two different gear types: open-circuit SCUBA (OC) and closed-circuit rebreather (CCR). Bubble exhaust released from the OC equipment is a potential source of bias for in-situ fish observations, as the associated audio and visual disturbances could either attract or repel fishes depending on whether their behavior is more driven by curiosity or caution. The study area, is a large (~1.5 million km2) and extremely remote marine protected area in which the response of coral reef fishes to divers represent natural behavior of naive fishes with little or no previous contact with humans. Historically, surveys conducted on OC in this area have shown an abundance of large roving piscivores and this study set out to determine the extant, if any, the audible and visual disturbances of OC bubbles have. The species typically seen in these prior surveys were Caranx ignobilis, Caranx melampygus, Aprion virescens, and a couple of species of sharks. We found differences in counts for some roving piscivores, including significantly more jacks observed on OC than CCR (Caranx ignobilis 57% more, and Caranx melampygus 113% more). Instance of first encounter, i.e. the time when a fish was first observed during a survey, also varied for some species. Higher numbers of Aprion virescens (p = 0.04), and C. melampygus (p = <0.001) were observed in the first 5-minutes of counts by divers on OC (i.e. when they were using breathing apparatus that produced noises that could be heard over long distances). Although not the focus of the study, we also assessed differences between OC and CCR counts for other groups of fishes. Estimated abundance of benthic damselfish was higher on OC than CCR, and counts of butterflyfish were lower on OC; but there were no significant differences for the other groups considered. This is an important control study that documents the natural responses of coral reef fishes to SCUBA bubbles generated by in-situ surveys.

НАУЧНАЯ ЖИЗНЬ СРЕДИ ЛЬДОВ АРКТИКИ И АНТАРКТИКИ: К 80-ЛЕТИЮ И.А. МЕЛЬНИКОВА

The article is dedicated to the anniversary of Igor Alekseevich Melnikov, chief researcher at the Institute of Oceanology, Doctor of Biological Sciences. Out of 50 years of work at the Institute of IO RAS, four decades of his scientific activity are devoted to research in the Arctic and Antarctic. Starting from the International Polar Year in 2007 to the present, I.A. Melnikov conducts bipolar monitoring of marine water-ice ecosystems that are affected by climate change. His scientific views were widely reflected in both the specialized and periodicals, as well as in radio and television appearances. I.A. Melnikov was awarded the title “Honorable Polar Explorer”, awarded the Order of the “Trudovogo Krasnogo Znameny”, and for scientific research using scuba gear under the ice of the Arctic and Antarctic, he was awarded the UNESCO International Grand Prix.

ASOSIASI ANTARA TUTUPAN KOMUNITAS KARANG DENGAN KOMUNITAS IKAN TERUMBU KARANG DI PESISIR TIMUR PULAU BIAK, KABUPATEN BIAK NUMFOR

Ekosistem terumbu karang memiliki banyak manfaat termasuk melindungi pantai dari gelombang dan arus yang kuat serta penting dalam menjaga sistem ekologi di perairan yaitu sebagai habitat, tempat pemijahan, tempat berteduh dan sumber makanan untuk biota laut seperti ascidian, spons, echinodermata, moluska, dan ikan. Keanekaragaman ikan karang di pesisir timur Pulau Biak adalah salah satu sumberdaya penting yang dimanfaatkan sebagai sumber pendapatan atau sumber makanan oleh penduduk yang mencari nafkah sebagai nelayan. Penelitian ini bertujuan untuk menganalisis hubungan antara komunitas karang dan komunitas ikan karang di pesisir timur Pulau Biak, Kabupaten Biak Numfor. Pengamatan dilakukan dengan menyelam menggunakan peralatan SCUBA. Pengamatan kondisi terumbu karang menggunakan metode PIT (Point Intercept Transect) dan ikan terumbu karang dengan metode UVC (Underwater Visual Census). Analisis data dilakukan dengan analisis uji Spearman. Hasil penelitian menunjukkan bahwa perubahan tutupan komunitas karang mempengaruhi komunitas ikan karang. Kesimpulan dari penelitian ini adalah terdapat asosiasi antara komunitas karang dan komunitas ikan karang yang memiliki hubungan linier positif.

An attempt at hydroacoustic localization of an open-circuit scuba diver.

Passive acoustic monitoring of scuba divers is a promising way to ensure the safety of recreational divers and prevent waterside intrusion by terrorists. It is shown experimentally that the low-frequency underwater respiratory-associated noise of an open-circuit scuba diver can be used successfully to monitor the respiratory rate at distances of up to 100 m. Respiratory-associated noise in the frequency band of 30-1200 Hz provides the possibility of localizing an open-circuit scuba diver in a noisy shallow-water area by using two pairs of hydrophones at distances of up to 220 m and with a predominant discrepancy of no more than 10 m in comparison with Global Positioning System data.

Muertes en el buceo: un modelo de investigación multidisciplinar

Diving is one of the most practiced underwater activities on the Spanish coast. The most common methods used in diving activities are SCUBA (self-contained underwater breathing apparatus), CCR (closed circuit rebreather) and SCR (semi-closed circuit rebreather). Although recreational diving is safe overall, diving accidents are potentially serious and even fatal. Despite all the precautions taken by divers, fatalities related to this activity are reported every year. Drowning is the main cause of death, but others have been described, such as arterial gas embolism, decompression sickness, natural pathology, and trauma. Autopsies of SCUBA diving-related deaths are a big challenge for any forensic pathologist. It is advisable to have some knowledge about diving physiopathology and experience in the practice of special autopsy techniques. Collaboration with a multidisciplinary team provides enough information, evidence and pathological findings for highly-qualified investigation of the incidents to be able to prevent similar incidents in the future.

Physical Exercise Intensity During Submersion Selectively Affects Executive Functions.

The intact cognitive processing capacity in highly demanding and dynamically changing situations (e.g., in extreme environmental conditions) is of central relevance for personal safety. This study therefore investigated whether underwater physical exercise (PE) affected cognitive performance by comparing these effects during underwater fin-swimming as opposed to inactivity under normal environmental conditions. Although acute bouts of PE can modulate cognitive performance under highly controlled and standardized laboratory conditions, no previous study has determined whether PE acutely modulates cognitive performance in non-laboratory testing conditions involving extreme environments (e.g., underwater). A total of 27 healthy volunteers (16 males and 11 females; 28.9 ± 7.4 years of age) participated in two experiments involving either moderate or high PE intensity. A PRE/POST crossover design was employed among participants while performing cognitive tests in a counterbalanced order (i.e., before and after 20 min of PE in submersion [WET] and once before and after inactivity [DRY] while in the laboratory). Cognitive performance was measured as a combination of executive functions through the Eriksen Flanker (inhibition) and Two-Back (working memory) Tasks using an underwater tablet computer. ANOVAs revealed enhanced reaction times only in the Flanker test after moderate PE for the WET condition. No other effects were detected. These findings indicate that cognitive performance is exercise-intensity-dependent with enhanced effects during moderate PE, even in extreme environments (i.e., underwater). These results should be relevant in recreational and occupational contexts involving underwater activity and may also apply to microgravity (e.g., during extra-vehicular activities). This study compared the acute effects of physical exercise (PE) on cognitive performance in an underwater environment while participants fin-swam with SCUBA (self-contained underwater breathing apparatus) gear. Findings revealed that 20 min of moderate PE positively affected cognitive performance (i.e., inhibitory control ability). However, no changes were observed after high-intensity exercise.

Gas micronuclei underlying decompression bubbles may explain the influence of oxygen enriched gases during decompression on bubble formation and endothelial function in self-contained underwater breathing apparatus diving

Gas micronuclei underlying decompression bubbles may explain the influence of oxygen enriched gases during decompression on bubble formation and endothelial function in self-contained underwater breathing apparatus diving

Influence of oxygen enriched gases during decompression on bubble formation and endothelial function in self-contained underwater breathing apparatus diving: a randomized controlled study

AimTo assess the effect of air, gas mixture composed of 50% nitrogen and 50% oxygen (nitrox 50), or gas mixture composed of 1% nitrogen and 99% oxygen (nitrox 99) on bubble formation and vascular/endothelial function during decompression after self-contained underwater breathing apparatus diving.MethodsThis randomized controlled study, conducted in 2014, involved ten divers. Each diver performed three dives in a randomized protocol using three gases: air, nitrox 50, or nitrox 99 during ascent. The dives were performed on three different days limited to 45 m sea water (msw) depth with 20 min bottom time. Nitrogen bubbles formation was assessed by ultrasound detection after dive. Arterial/endothelial function was evaluated by brachial artery flow mediated dilatation (FMD) before and after dive.ResultsNitrox 99 significantly reduced bubble formation after cough compared with air and nitrox 50 (grade 1 vs 3 and vs 3, respectively, P = 0.026). Nitrox 50 significantly decreased post-dive FMD compared with pre-dive FMD (3.62 ± 5.57% vs 12.11 ± 6.82% P = 0.010), while nitrox 99 did not cause any significant change.ConclusionNitrox 99 reduced bubble formation, did not change post-dive FMD, and decreased total dive duration, indicating that it might better preserve endothelial function compared with air and nitrox 50 dive protocols.

Diving-related fatalities: multidisciplinary, experience-based investigation.

To describe the technical characteristics of fatal diving mishaps and to elucidate the causes of death using a sequence analysis and a multidisciplinary investigation of diving-related fatalities. All cases of diving deaths recorded on the coast of Girona (Spain) between January 2009 and May 2018 were analyzed. Most data were obtained from the police technical reports and the forensic pathology service. Each accident was analyzed in order to identify the trigger, disabling agent, disabling injury, and cause of death. During the study period 25 diving-related fatalities were recorded. Most of the victims were males aged 50-69years, and 11 were experienced divers. Almost all victims were using open-circuit SCUBA to breathe with compressed air as their sole gas supply. None of the victims were diving alone. The most common identified triggers included exertion, panic, buoyancy problems, disorientation and confusion. The main factors identified as disabling agents were rapid ascent, a cardiac incident, panic and entrapment. Asphyxia, lung over expansion, and myocardial ischemia were the most frequent disabling injuries. Finally, drowning represented the main cause of death, followed by arterial gas embolism and natural causes or internal diseases. A differential diagnosis, performed in the setting of a multidisciplinary investigation, is essential for elucidating the cause of death in diving-related fatalities. The proposed sequence analysis allows to clarify underlying problems in these cases and to identify risk factors and unsafe behaviors in diving.

Diversity and structure of epibenthic communities of the red algae zone in the White Sea

At high latitudes, the marine transitional zone between the highly productive kelp communities and the devoid of vegetation deep-waters is occupied mainly by number of red algae species, both encrusting and cespitose, which associate with rich and diverse fauna. However, zoologists and botanists never scrutinized these communities in equal manner up to present. We investigated the transition red algae zone in the White Sea in summer 2016 and 2017 using scuba equipment. The photic depth is limited to 18–23 m at different locations. Sessile species prevail among 315 epibenthic organisms in species number ( ~ 80%) and biomass ( ~ 90%). Communities of the red algae zone are rich in species (from 54 to 177). The most distinct differences were observed between the communities of Kandalaksha and Onega Bays. Vertical heterogeneity of the red algae zone was revealed; at most locations, Rhodophyta predominate in the upper subzone and Cirripedia predominate in the lower parts of the red algae zone. At the investigated depths, shallow-water and deep-water sets of species were defined. Interspecific spatial interactions between sessile organisms are revealed: 72.2 ± 3.5% of them were recorded as epibionts, and 29.1 ± 2.5% were registered as basibionts. These interactions provide evidence of the increase of species diversity: 32.7 ± 6.8% of sessile taxa were recorded exclusively as epibionts. Algae Phycodrys rubens, Odonthalia dentata, and Coccotylus truncatus, ascidian Styela rustica, barnacles Balanus crenatus, Verruca stroemia, and polychaete Pista maculata are foundation species, each supporting multi-level suites (up to four levels) of dependent species.

Benthic habitats in the Tikhaya Bight (the Hooker Island, Franz Josef Land)

Benthic habitats of Tikhaya Bight (Hooker Island, Franz Josef Land, High Arctic) were studied by using SCUBA equipment (diving quantitative method) and Van Veen grabs. Three main communities have been described. A Gammarus setosus-macroalgae community, probably seasonal, developed above 5 meters depth, had a relatively low diversity with biomass 7.6±0.9 g/m2 and abundance 135±40 ind/m2; a mixed bivalves-amphipods-bryozoan community (Serripes groenlandicus, Mya truncata, Haploops laevis, Alcyonidium disciforme) occured in muddy bottoms with some interspersed boulders between 7 and 30 m depth; it included 101 taxons, had a relatively high biomass 152.3±114.2 g/m2 and abundance 1600±940 ind/m2. A bivalve-dominated community with Musculus niger and Yoldia hyperborean inhabited depth of 67–72 m, included 38 taxons and was characterized by high density of abundance and biomass – 670±295 ind/m2 and 356.1±57.1 g/m2, respectively. Comparison with the previous data obtained 20 years ago at the depth 7–30 m, showed that, possibly, the retreat of the glacier under the influence of increasing temperature in the environment and increased runoff of melt water, washes away clay deposits which led to siltation of the bottom in the bay and caused degradation of kelp, which was partially replaced by invertebrate communities inherent in silted soils.

SCUBA Medicine for otolaryngologists: Part I. Diving into SCUBA physiology and injury prevention.

Introduce pertinent self-contained underwater breathing apparatus (SCUBA) physiology and corresponding terminology. Appreciate the scope of diving and related otolaryngological injury. Illustrate pathophysiologic mechanisms for diving injuries. Summarize strategies for ear, paranasal sinus, and lung barotrauma prevention, including medical optimization and autoinsufflation techniques. We conducted a review of the available medical and diving literature in English, German, Spanish, Italian Turkish, and French to determine the degree of evidence or lack thereof behind recommendations for treating SCUBA divers. The databases of PubMed, Ovid Medline, and the Cochrane library, as well available textbooks, were queried for relevant data. Divers are subjected to large pressure gradients within the first few meters of descent. This can lead to gas embolism formation as well as barotrauma secondary to gas expansion/compression in potential closed spaces such as the middle ear, paranasal sinuses, and lungs. Physicians can minimize the risk of injury by counseling patients regarding proper equalization and descent/ascent techniques, and optimizing sinonasal and eustachian tube function. The use of decongestants is controversial. Diving is an increasingly popular sport with predominantly otolaryngologic manifestations of injury and disease. Treating SCUBA divers requires a firm understanding of how physiology is altered underwater. This review presents the relevant background information using illustrations to understand the environmental forces acting on divers and how to prevent injury. Laryngoscope, 130:52-58, 2020.

SCUBA Medicine for Otolaryngologists: Part II. Diagnostic, Treatment, and Dive Fitness Recommendations.

Challenge current practices and misconceptions in treating recreational SCUBA (Self-contained underwater breathing apparatus) divers. Differentiate patients who are fit to dive and those with relative and absolute contraindications. Redefine the standard of care for fitness to dive parameters based on the most up-to-date evidence. We conducted a review of the available medical and diving literature in English, German, Spanish, Italian, Turkish, and French to determine the degree of evidence or lack thereof behind recommendations for treating SCUBA divers. The databases of PubMed, Ovid Medline, and Cochrane library, as well as available textbooks, were queried for relevant data. Current recommendations regarding fitness to dive are overly prohibitive given the available evidence. Insufficient evidence currently exists to justify the level of certainty with which some recommendations have been made previously. This is particularly true with regard to postsurgical patients, including those who have undergone stapedectomy or skull base repairs. Updated treatment guidelines, particularly those regarding the timely differentiation of barotrauma and decompression sickness, as well as clearance for return to diving following surgery or trauma, are presented herein. Current guidelines for otorhinolaryngologists governing the diagnosis and treatment of SCUBA divers are lacking and in some instances founded on insufficient evidence. We present an up-to-date, comprehensive guide for otorhinolaryngologists to utilize going forward. Laryngoscope, 130:59-64, 2020.

The Creation and Perception of Underwater Built Environment or Architecture

It is obvious that the underwater architectural space is formed as the result of the contemporary human construction activity. Underwater exist built environment available to the modern man. Below the surface of the water is a space that is shaped in a way that makes an architecture. The creation of underwater space has lot of ways and methods. There are a significant desperation between the imagination of designers and the real construction made underwater. Also the problem of different perception of underwater spaces are significant problem. Human body is used to live in the air at the normal pressure of 1at, and in the environment of air. The water is not the natural environment for people so there are important differences of perception of architectural space existing below the surface. Physical conditions of underwater facilities are very different from the ground conditions and it must be considered by visionaries and concept makers to have a chance to implement them. The space of water below the surface is full of stuff which is placed or constructed by the people. Most of them are very simple construction, placed for the recreation purpose. There are dozens of futuristic visions of underwater habitats, but at present times, it is not possible to notice that designers find the way of development, which follow their imaginations. There are not exist the futuristic structures or glass domes. Most of the constructed underwater architecture is available only with the SCUBA equipment. The author as the licenced architect (since 1994) and the designer of several objects connected with water, and the instructor of the Underwater Activity Committee trying to find the purpose and the reason why the human being must (or try) to live at the enemy environment of underwater.

Theoretical model and experimental validation for underwater oxygen extraction for realizing artificial gills

Many recent studies have employed biomimicry to develop practical systems inspired by natural mechanisms. For instance, several attempts have been made to develop an artificial gill system by mimicking plastron mechanisms, which demonstrates the potential for terrestrial animals to breathe under water by extracting dissolved oxygen and discharging carbon dioxide. In this study, we propose a theoretical model for such artificial gill system comprising essential engineering parameters such as the partial pressure of oxygen inside the system, gas permeability, surface area, and the thickness of membranes. We experimentally investigated the effect of each engineering parameter on the oxygen extraction/supply rate and then validated the theoretical model with experimental results. We also applied the same model and engineering guidelines to develop a scaled-up artificial gill system for a stag beetle. The artificial gill system extracts sufficient dissolved oxygen from water, thus demonstrating that stag beetle can survive for more than 60 h in water; however, carbon dioxide accumulates over time. We believe that the established model and supporting experimental results can further advance artificial gill technology, thereby making it possible for humans to breathe under water without using a conventional scuba gear.

Artistic endeavors strive to save coral reefs

The gallery of artist Colleen Flanigan is harder to visit than most. On one clear day in January, Flanigan suited up in scuba gear at the Sand Dollar Sports Dive Shop in Cozumel, Mexico, swam 60 meters out to sea, and dove 4 meters down to her latest installation. Zoe–A Living Sea Sculpture is a loosely helical structure, formed by welded rebar and steel mesh that arch 6 feet upward and root firmly in the ocean floor. Years in the making, the work is “living” because Flanigan hopes it will continue to make itself. Artist Colleen Flanigan’s Zoe–A Living Sea Sculpture in Cozumel, Mexico, is both underwater art and coral restoration experiment. Here, master scuba trainer Ernesto Martinez helps attach found coral fragments. Image courtesy of Colleen Flanigan. By running low-voltage electricity through the metalwork, using a technology called Biorock (1), Flanigan creates a zone of higher pH that attracts minerals to accrete on the structure. Next, she attaches coral fragments that can then cement themselves. Coral larvae and other organisms could also colonize Zoe , taking it in unpredictable directions of texture and color. The idea, although still controversial, is that the Biorock structure both provides a mineral substrate for corals to grow on and generates an electrical field that enhances the ability of coral and other marine organisms to grow faster. Around the world, coral reefs are threatened by local stressors, such as overfishing and pollution, and global ones, such as warming waters and ocean acidification (2). Last year marked the end of a 3-year bleaching event during which high ocean temperatures in many reefs across the globe caused corals to expel their symbiotic algae, draining the corals of color and depriving them of their primary energy source (3). Looking to draw attention to these bleak trends, …

Medical Management and Risk Reduction of the Cardiovascular Effects of Underwater Diving.

Undersea diving is a sport and commercial industry. Knowledge of potential problems began with Caisson disease or "the bends", first identified with compressed air in the construction of tunnels under rivers in the 19th century. Subsequently, there was the commercially used old-fashioned diving helmet attached to a suit, with compressed air pumped down from the surface. Breathhold diving, with no supplementary source of air or other breathing mixture, is also a sport as well as a commercial fishing tool in some parts of the world. There has been an evolution to self-contained underwater breathing apparatus (SCUBA) diving with major involvement as a recreational sport but also of major commercial importance. Knowledge of the physiology and cardiovascular plus other medical problems associated with the various forms of diving have evolved extensively. The major medical catastrophes of SCUBA diving are air embolism and decompression sickness (DCS). Understanding of the essential referral to a hyperbaric recompression chamber for these problems is critical, as well as immediate measures until that recompression is achieved. These include the administration of 100% oxygen and rehydration with intravenous normal saline. Undersea diving continues to expand, especially as a sport, and a basic understanding of the associated preventive and emergency medicine will decrease complications and save lives.

Cellular Glucose Uptake During Breath-Hold Diving in Experienced Male Breath-Hold Divers

BackgroundThe physiological and pathophysiological mechanisms that govern diving, both self-contained underwater breathing apparatus (SCUBA) and breath-hold diving (BH-diving), are in large part well known, even if there are still many unknown aspects, in particular about cell metabolism during BH-diving.The scope of this study was to investigate changes in glycemia, insulinemia, and the catecholamine response to BH-diving, to better understand if the insulin-stimulated glucose uptake mechanism is involved in cellular metabolism in this sport.MethodsTwenty male experienced healthy breath-hold divers were studied. Anthropometric information was obtained. Glycemia, insulinemia, and catecholamine response were investigated before and after the series of BH-diving.ResultsWe found a statistically significant decrease in the blood glucose levels between before and after dives (mean 94.3 ± 11.6 vs. 83.5 ± 12.5 mg/dl) P = 0.001 and a statistically significant increase in blood insulin value (median 4.5 range 3.4/6.4 vs. 7.0 range 4.2/10.2 mcgU/ml) P < 0.0001. Also, we found a statistically significant increase of catecholamine production (median 14.0 range 8/18 vs. 15.5 range 10.0/21.0 μg) P < 0.0001.ConclusionsThe increase in blood insulin during BH-diving associated with the decrease of blood glucose levels could indicate that the upregulating cellular uptake is not caused by activation of the specific glucose transporters.Particular diving-related conditions such as the diving reflex, the intermittent hypoxia/hyperoxia, and the particular environmental condition could play an important role in the mechanism involved in glycemia decrease in BH-diving.Our data confirm that the adaptations to BH-diving are caused by complex mechanisms and involve many peculiar responses still in large part unknown.

SCUBA Diving in Pregnancy.

Obstetrical care providers may occasionally encounter women with questions about the safety of Self-Contained Underwater Breathing Apparatus (SCUBA) diving in pregnancy. This article provides an overview of safety issues associated with basic SCUBA diving and offers guidance to practitioners about how to evaluate and counsel pregnant women about the associated maternal and fetal risks. Basic diving physiology is reviewed and the implications of SCUBA diving during pregnancy are discussed. A literature review examined available animal and human data about the potential adverse effects of the physiological changes of pregnancy on divers, the impact of pressure changes during diving, and possible consequences of hyperbaric gas exposure and rapid decompression on mother and fetus. Studies were found by searching the terms "scuba diving," "pregnancy," "fetus," "decompression illness," "hyperbaric medicine," and "animal studies" in the databases Medline, Pubmed, and Embase. Reference lists from existing articles and reports from identified diving magazines were also reviewed. Studies were limited to the English language and included publications until 2016. All relevant human studies were selected. Five retrospective studies and one prospective study assessing the antenatal and postnatal outcomes of women who participated in SCUBA diving while pregnant were reviewed. Published data was limited in both quantity and quality. The authors' experience with SCUBA diving together with a background in obstetrics allowed themes to be explored and recommendations developed. In addition to established risks of SCUBA diving, pregnant women are at increased risk due to changes in body habitus (affecting equipment fitting and balance). Animal data suggest possible adverse fetal effects due to fetal decompression illness (DCI) and hyperbaric oxygen exposure. Human data, though generally reassuring, are of poor quality and thus do not completely exclude adverse outcomes. In general, women should be cautioned to avoid diving during pregnancy, but inadvertent exposure to recreational diving in early pregnancy is not a reason for pregnancy termination.