Breath hold diving

Pulmonary gas exchange in breath-hold diving (BHD) consists of a progressive increase in arterial partial pressures of oxygen ([Formula: see text]) and carbon dioxide ([Formula: see text]) during descent. However, recent findings have demonstrated that [Formula: see text] does not consistently rise in all subjects. This study aimed at verifying and explaining [Formula: see text] derangements during BHD analyzing arterial blood gases and searching for pulmonary alterations with lung ultrasound. After ethical approval, 14 fit breath-hold divers were included...

Freediving is a type of diving in which divers rely solely on how long they can hold their breath underwater during their dive, which is why it can also be referred to as 'breath-hold diving'. Unlike scuba (self-contained underwater breathing apparatus) diving, individuals do not require training or licencing to perform freediving and may not be aware of the risks of this activity. This paper presents a case in which coastguards retrieved a free diver's lifeless body from the seafloor. In most cases such as this, the deceased individual's cause of death would be ruled as drowning...

Tissue and blood gas embolism (GE) associated with fisheries bycatch are likely a widespread, yet underestimated, cause of sea turtle mortality. Here, we evaluated risk factors associated with tissue and blood GE in loggerhead turtles caught incidentally by trawl and gillnet fisheries on the Valencian coastline of Spain. Of 413 turtles (303 caught by trawl, 110 by gillnet fisheries), 54% ( n  = 222) exhibited GE. For sea turtles caught in trawls, the probability and severity of GE increased with trawl depth and turtle body mass...

Diving is central to the foraging strategies of many marine mammals and seabirds. Still, the effect of dive depth on foraging cost remains elusive because energy expenditure is difficult to measure at fine temporal scales in wild animals. We used depth and acceleration data from 8 lactating California sea lions (Zalophus californianus) to model body density and investigate the effect of dive depth and tissue density on rates of energy expenditure. We calculated body density in 5 s intervals from the rate of gliding descent...

PURPOSE: To examine the effect of freediving depth on risk for hypoxic blackout by recording arterial oxygen saturation (SpO2 ) and heart rate (HR) during deep and shallow dives in the sea. METHODS: Fourteen competitive freedivers conducted open-water training dives wearing a water-/pressure proof pulse oximeter continuously recording HR and SpO2 . Dives were divided into deep (> 35 m) and shallow (10-25 m) post-hoc and data from one deep and one shallow dive from 10 divers were compared...

Fish moving between different thermal environments experience heat exchange via conduction through the body wall and convection from blood flow across the gills. We report a strategy of preventing convective heat loss at the gills during excursions into deep, cold water by the tropical scalloped hammerhead shark ( Sphryna lewini ). Adult scalloped hammerhead sharks dive rapidly and repeatedly from warm (~26°C) surface waters to depths exceeding 800 meters with temperatures as low as 5°C. Biologgers attached to adult sharks show that warm muscle temperatures were maintained throughout the deepest portion of each dive...

Hammerhead sharks hold their breath when diving to regulate body temperature.

Cetaceans exhibit physiological adaptations that allowed the transition to aquatic life, including a robust antioxidant defense system that prevents injury from repeated exposure to ischemia/reperfusion events associated with breath-hold diving. The signaling cascades that characterize ischemic inflammation in humans are well characterized. In contrast, cetaceans' molecular and biochemical mechanisms that confer tolerance to inflammatory events are poorly understood. Heme oxygenase (HO) is a cytoprotective protein with anti-inflammatory properties...

PURPOSE: Hyperventilation is considered a major risk factor for hypoxic blackout during breath-hold diving, as it delays the apnea breaking point. However, little is known about how it affects oxygenation, the diving response, and spleen contraction during serial breath-holding. METHODS: 18 volunteers with little or no experience in freediving performed two series of 5 apneas with cold facial immersion to maximal duration at 2-min intervals. In one series, apnea was preceded by normal breathing and in the other by 15 s of hyperventilation...

For the purposes of this guideline, a diving accident is defined as an event that is either potentially life-threatening or hazardous to health as a result of a reduction in ambient pressure while diving or in other hyperbaric atmospheres with and without diving equipment. This national consensus-based guideline (development grade S2k) presents the current state of knowledge and recommendations on the diagnosis and treatment of diving accident victims. The treatment of a breath-hold diver as well as children and adolescents does not differ in principle...

INTRODUCTION: Breath-hold (BH) diving has known risks, for example drowning, pulmonary oedema of immersion and barotrauma. There is also the risk of decompression illness (DCI) from decompression sickness (DCS) and/or arterial gas embolism (AGE). The first report on DCS in repetitive freediving was published in 1958 and from then there have been multiple case reports and a few studies but no prior systematic review or meta-analysis. METHODS: We undertook a systematic literature review to identify articles available from PubMed and Google Scholar concerning breath-hold diving and DCI up to August 2021...

INTRODUCTION: Recreational freedivers typically perform repeated dives to moderate depths with short recovery intervals. According to freediving standards, these recovery intervals should be twice the dive duration; however, this has yet to be supported by scientific evidence. METHODS: Six recreational freedivers performed three freedives to 11 metres of freshwater (mfw), separated by 2 min 30 s recovery intervals, while an underwater pulse oximeter measured peripheral oxygen saturation (SpO2 ) and heart rate (HR)...

The dive response allows marine mammals to perform prolonged breath-hold dives to access rich marine prey resources. Via dynamic adjustments of peripheral vasoconstriction and bradycardia, oxygen consumption can be tailored to breath-hold duration, depth, exercise, and even expectations during dives. By investigating the heart rate of a trained harbor porpoise during a two-alternative forced choice task, where the animal is either acoustically masked or blindfolded, we test the hypothesis that sensory deprivation will lead to a stronger dive response to conserve oxygen when facing a more uncertain and smaller sensory umwelt...

Syncope or "blackout" (BO) in breath-hold diving (freediving) is generally considered to be caused by hypoxia. However, it has been suggested that cardiac arrhythmias affecting the pumping effectivity could contribute to BO. BO is fairly common in competitive freediving, where athletes aim for maximal performance. We recorded heart rate (HR) during a static apnea (STA) competition, to reveal if arrhythmias occur. Four male freedivers with STA personal best (PB) of 349±43s, volunteered during national championships, where they performed STA floating face down in a shallow indoor pool...

Marine mammals are divided into three groups, with similar adaptations resulting from their aquatic lifestyle: sirenians, pinnipeds, and cetaceans. The present work focused on the South American fur seal, or Arctocephalus australis , a carnivore included in the pinnipeds group. We assessed whether the anatomical features of the Arctocephalus australis' respiratory system are comparable to those of other land-carnivores or whether these individuals show anatomical adaptations related to their ability to dive or their breath-holding capacities...

The extraordinary breath-hold diving capacity of crocodilians has been ascribed to a unique mode of allosterically regulating hemoglobin (Hb)-oxygenation in circulating red blood cells. We investigated the origin and mechanistic basis of this novel biochemical phenomenon by performing directed mutagenesis experiments on resurrected ancestral Hbs. Comparisons of Hb function between the common ancestor of archosaurs (the group that includes crocodilians and birds) and the last common ancestor of modern crocodilians revealed that regulation of Hb-O2 affinity via allosteric binding of bicarbonate ions represents a croc-specific innovation that evolved in combination with the loss of allosteric regulation by ATP binding...

PURPOSE: To showcase results of arterial blood gases' analysis in elite breath-hold divers sampled at depths where their total lung capacities are below their residual lung volume on surface. METHODS: Three male elite breath-hold divers performed body plethysmographies to determine their lung volumes. Two dives were performed, one on normal inhalation to 60 m of depth and the second on complete exhalation to 10 m of depth. Blood samples were taken on five occasions; before the first dive, at 60 and 10 m of depth and immediately after resurfacing after both dives...

Odontocetes are breath-hold divers with a suite of physiological, anatomical, and behavioral adaptations that are highly derived and vastly different from those of their terrestrial counterparts. Because of these adaptations for diving, odontocetes were originally thought to be exempt from the harms of nitrogen gas embolism while diving. However, recent studies have shown that these mammals may alter their dive behavior in response to anthropogenic sound, leading to the potential for nitrogen supersaturation and bubble formation which may cause decompression sickness in the central nervous system (CNS)...

This case report and literature review aim to explore the range of injuries sustained in the sport of freediving. The case report involves a 37-year-old patient who sustained a pneumothorax secondary to freediving. We conducted the literature review to analyse the injuries associated with freediving. We used the combination of search terms 'freediving", "injuries", and "breath-hold diving" on the database PubMed®. A total of 40 studies were eligible for inclusion in this review. The search revealed a wide range of ophthalmological, pulmonary, neurological, ear, nose, and throat injuries, along with several fatalities...

RATIONALE: Static apnoeas performed after an overnight fast as opposed to postprandially have been evinced to improve apnoeic performance. However, no study has explored the effect of dietary intake on apnoeic performance, cardiovascular nor splenic responses over a series of repeated apnoeas. METHOD: Ten healthy adults attended the laboratory on three separate occasions (≥48-h apart) after: a 14-h fast (F14), 1-h post consumption of a high-calory-high-carbohydrate (HCHC) or a low-calory-low-carbohydrate (LCLC) based-meal...