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Breath hold diving

A Fahlman, M Brodsky, S Miedler, S Dennison, M Ivančić, G Levine, J Rocho-Levine, M Manley, J Rocabert, A Borque Espinosa
We measured respiratory flow ( V̇ ), breathing frequency ( f R ), tidal volume ( V T ), breath durations, and end-expired O2 content in bottlenose dolphins ( Tursiops truncatus ) before and after static surface breath-holds ranging from 34 to 292 s. There was considerable variation in the end-expired O2 , tidal volume V T , and f R following a breath-hold. The analysis suggests that the dolphins attempt to minimize recovery following a dive by altering V T , and f R to rapidly restore the O2 stores. For the first breath following a surface breath-hold, the end-expired O2 decreased with dive duration, while V T , and f R increased...
February 13, 2019: Journal of Experimental Biology
Marco Bonato, Paola Bagnoli, Cinzia Centelleghe, Mike Maric, Ginevra Brocca, Sandro Mazzariol, Bruno Cozzi
The retia mirabilia are vascular nets composed by small vessels dispersed among numerous veins, allowing blood storage, regulation of flow, and pressure damping effects. Here we investigated their potential role during the diving phase of the bottlenose dolphin ( Tursiops truncatus ). To this effect, the whole vertebral retia mirabilia of a series of dolphins were removed during post-mortem analysis and examined to assess vessel diameters, estimate vascular volume, and flow rate. Here we formulate a new hemodynamic model to help clarify vascular dynamics throughout the diving phase, based on the total blood volume of a bottlenose dolphin, and using data available about the perfusion of the main organs and body systems...
February 13, 2019: Journal of Experimental Biology
Alice Bliznyuk, Hava Golan, Yoram Grossman
Divers that are exposed to high pressure (HP) above 1.1 MPa suffer from High Pressure Neurological Syndrome (HPNS), which is implicated with central nervous system (CNS) malfunction. Marine mammals performing extended and deep breath-hold dives are exposed to almost 20 MPa without apparent HPNS symptoms. N -methyl-D-aspartate receptor (NMDAR) has repeatedly been implicated as one of the major factors in CNS hyperexcitability as part of HPNS. Electrophysiological studies in rat brain slices at He HP showed a significant increase in the synaptic NMDAR response, followed by postsynaptic excitability changes...
2018: Frontiers in Physiology
Youichi Yanagawa, Kazuhiko Omori, Ikuto Takeuchi, Kei Jitsuiki, Hiromichi Ohsaka, Kouhei Ishikawa
Commercial or occupational breath-hold (BH) harvest divers along the coast and islands of Japan are collectively called Ama divers. Repetitive BH diving by Ama divers may place them at risk of developing neurological decompression sickness (DCS). We report a 74-year-old Ama diver who demonstrated right hemiparesis during an ascent after free diving at a depth of 5 metres' sea water. This report suggests the usefulness of on-site ultrasound for making a differential diagnosis of DCS from endogenous cerebral ischaemia...
December 24, 2018: Diving and Hyperbaric Medicine: the Journal of the South Pacific Underwater Medicine Society
Gerardo Bosco, Alex Rizzato, Luca Martani, Simone Schiavo, Ennio Talamonti, Giacomo Garetto, Matteo Paganini, Enrico M Camporesi, Richard E Moon
The present study aimed to evaluate the partial pressure of arterial blood gases in breath-hold divers performing a submersion at 40 m. Eight breath-hold divers were enrolled for the trials held at "Y-40 THE DEEP JOY" pool (Montegrotto Terme, Padova, Italy). Prior to submersion, an arterial cannula in the radial artery of the non-dominant limb was positioned. All divers performed a sled-assisted breath-hold dive to 40 m. Three blood samplings occurred: at 10 min prior to submersion, at 40 m depth, and within 2 min after diver's surfacing and after resuming normal ventilation...
2018: Frontiers in Physiology
Tanja Mijacika, Otto Barak, Per Lav Madsen, Zeljko Dujic
The underwater environment challenges human physiology in a unique way. Prolonged exposure to extreme conditions of immersion and increased ambient pressure can lead to injury and even death. Breath-hold and diving with self-contained underwater breathing apparatus (SCUBA diving) pose acute stress predominantly on the cardiovascular and pulmonary system. Currently there is no evidence of long-term consequences of subclinical cardiovascular, neurological or pulmonary adverse effects, but diving has acute stresses on the human physiology...
November 12, 2018: Ugeskrift for Laeger
Jochen D Schipke, Lars Eichhorn, Patrick Behm, Sinclair Cleveland, Malte Kelm, Florian Boenner
BACKGROUND: Breath-hold diving has increasingly established itself within the leisure sector as near-natural sport. In parallel, a number of competitive disciplines have developed. To reach greater depths various breathing maneuvers are employed one of them being glossopharyngeal insufflation (GI), for which air is repetitively "pumped" into the lungs in order to increase the intrathoracic air volume. As intrapulmonary pressure is considerable increased in parallel, venous return is impeded, leading to incomplete filling of the cardiac chambers...
October 30, 2018: Scandinavian Journal of Medicine & Science in Sports
Carla Guerreiro, Andreia Teixeira, Tiago Marques, Sofia Reimão
No abstract text is available yet for this article.
October 30, 2018: Neurology
Thomas Kjeld, Nis Stride, Anders Gudiksen, Egon Godthaab Hansen, Henrik Christian Arendrup, Peter Frederik Horstmann, Bo Zerahn, Lars Thorbjørn Jensen, Nikolai Nordsborg, Jacob Bejder, Jens Frey Halling
BACKGROUND: The performance of elite breath hold divers (BHD) includes static breath hold for more than 11 minutes, swimming as far as 300 m, or going below 250 m in depth, all on a single breath of air. Diving mammals are adapted to sustain oxidative metabolism in hypoxic conditions through several metabolic adaptations, including improved capacity for oxygen transport and mitochondrial oxidative phosphorylation in skeletal muscle. It was hypothesized that similar adaptations characterized human BHD...
2018: PloS One
John Lippmann, Chris Lawrence, Andrew Fock, Scott Jamieson
INTRODUCTION: An individual case review of known diving-related deaths that occurred in Australia in 2012 was conducted. METHOD: The case studies were compiled using statements from witnesses and reports of the police and coroners. In each case, the particular circumstances of the accident and details from the post-mortem examination, where available, are provided. RESULTS: There were 26 reported fatalities (four less than the previous year)...
September 30, 2018: Diving and Hyperbaric Medicine: the Journal of the South Pacific Underwater Medicine Society
B Jones, C E Cooper
The development of underwater Near-Infrared Spectroscopy (uNIRS) has enabled the measurement of tissue oxygenation within the swim environment. Unique physiological responses, such as the diving reflex, have been shown to occur during synchronized swimming and demonstrate an innate oxygen-conserving reflex. However, the prevalence of a sudden loss of consciousness ('hypoxic blackout') is an ongoing concern in this swim population. The purpose of this study was to investigate the reported low tissue oxygen conditions experienced in elite level synchronized swimmers (SyncS) during swim routines...
2018: Advances in Experimental Medicine and Biology
Ran Arieli
Decompression bubbles can develop only from pre-existing gas micronuclei. These are the nanobubbles which appear on active hydrophobic spots (AHS) found on the luminal aspect of all blood vessels. Following decompression, with the propagation of blood along the arterial tree, diffusion parameters cause increased transfer of nitrogen from the tissue into the artery, and more so if perfusion is low. Taravana is a neurological form of decompression illness (DCI) prevalent in repeated breath-hold diving. A nanobubble on an AHS in a distal artery of the brain may receive an influx of nitrogen after each dive until it occludes the arterial blood flow...
August 30, 2018: Respiratory Physiology & Neurobiology
F A Fernandez, R Martin-Martin, I García-Camacha, D Juarez, P Fidel, J M González-Ravé
The current study aimed to analyze the effects of physical conditioning inclusion on apnea performance after a 22-week structured apnea training program. Twenty-nine male breath-hold divers participated and were allocated into: (1) cross-training in apnea and physical activity (CT; n = 10); (2) apnea training only (AT; n = 10); and control group (CG; n = 9). Measures were static apnea (STA), dynamic with fins (DYN) and dynamic no fins (DNF) performance, body composition, hemoglobin, vital capacity (VC), maximal aerobic capacity (VO2max), resting metabolic rate, oxygen saturation, and pulse during a static apnea in dry conditions at baseline and after the intervention...
January 2019: Respiratory Physiology & Neurobiology
Melissa Ilardo, Rasmus Nielsen
Modern humans inhabit most of earth's harshest environments and display a wide array of lifestyles. Biological adaptations, in addition to technological innovations, have enabled these geographical and cultural explorations. The study of these adaptations helps not only to fundamentally understand our evolution as a species, but also may have increasing relevance as genomics transforms fields such as personalized medicine. Here we review three cultural and environmental shifts that have brought about adaptations in modern humans; the arctic, high altitudes, and a subsistence dependent on breath-hold diving...
August 1, 2018: Current Opinion in Genetics & Development
Andreas Fahlman, Frants H Jensen, Peter L Tyack, Randall S Wells
Bottlenose dolphins ( Tursiops truncatus ) are highly versatile breath-holding predators that have adapted to a wide range of foraging niches from rivers and coastal ecosystems to deep-water oceanic habitats. Considerable research has been done to understand how bottlenose dolphins manage O2 during diving, but little information exists on other gases or how pressure affects gas exchange. Here we used a dynamic multi-compartment gas exchange model to estimate blood and tissue O2 , CO2 , and N2 from high-resolution dive records of two different common bottlenose dolphin ecotypes inhabiting shallow (Sarasota Bay) and deep (Bermuda) habitats...
2018: Frontiers in Physiology
Andreas Fahlman, Katherine McHugh, Jason Allen, Aaron Barleycorn, Austin Allen, Jay Sweeney, Rae Stone, Robyn Faulkner Trainor, Guy Bedford, Michael J Moore, Frants H Jensen, Randall Wells
Diving mammals have evolved a suite of physiological adaptations to manage respiratory gases during extended breath-hold dives. To test the hypothesis that offshore bottlenose dolphins have evolved physiological adaptations to improve their ability for extended deep dives and as protection for lung barotrauma, we investigated the lung function and respiratory physiology of four wild common bottlenose dolphins ( Tursiops truncatus ) near the island of Bermuda. We measured blood hematocrit (Hct, %), resting metabolic rate (RMR, l O2 ⋅ min-1 ), tidal volume ( V T , l), respiratory frequency ( f R , breaths ⋅ min-1 ), respiratory flow (l ⋅ min-1 ), and dynamic lung compliance ( C L , l ⋅ cmH2 O-1 ) in air and in water, and compared measurements with published results from coastal, shallow-diving dolphins...
2018: Frontiers in Physiology
Lientra Q Lu, Michael B Strauss, Stuart S Miller
Introduction: Decompression sickness (DCS) has been associated with unusual circumstances such as breath-hold diving, shallow depths, and short bottom times. We report a case of DCS with an extraordinary cause and course. Materials and Methods: A 72-year-old healthy Hispanic female was referred to our 24/7 Hyperbaric Medicine Unit for emergency hyperbaric oxygen recompression treatment (HBO2 RCT) after developing lower-extremity paralysis following a hyperbaric air exposure in a homemade hyperbaric chamber...
May 2018: Undersea & Hyperbaric Medicine: Journal of the Undersea and Hyperbaric Medical Society, Inc
L Eichhorn, J Doerner, J A Luetkens, J M Lunkenheimer, R C Dolscheid-Pommerich, F Erdfelder, R Fimmers, J Nadal, B Stoffel-Wagner, H H Schild, A Hoeft, B Zur, C P Naehle
BACKGROUND: Prolonged breath holding results in hypoxemia and hypercapnia. Compensatory mechanisms help maintain adequate oxygen supply to hypoxia sensitive organs, but burden the cardiovascular system. The aim was to investigate human compensatory mechanisms and their effects on the cardiovascular system with regard to cardiac function and morphology, blood flow redistribution, serum biomarkers of the adrenergic system and myocardial injury markers following prolonged apnoea. METHODS: Seventeen elite apnoea divers performed maximal breath-hold during cardiovascular magnetic resonance imaging (CMR)...
June 18, 2018: Journal of Cardiovascular Magnetic Resonance
Jeppe Kaczmarek, Colleen Reichmuth, Birgitte I McDonald, Jakob H Kristensen, Josefin Larson, Fredrik Johansson, Jenna L Sullivan, Peter T Madsen
Long and deep dives in marine mammals are enabled by high mass-specific oxygen stores and the dive response, which reduces oxygen consumption in concert with increased peripheral vasoconstriction and a lowered heart rate during dives. Diving heart rates of pinnipeds are highly variable and modulated by many factors, such as breath holding (apnea), pressure, swimming activity, temperature and even cognitive control. However, the individual effects of these factors on diving heart rate are poorly understood because of the difficulty of parsing their relative contributions in diving pinnipeds...
July 9, 2018: Journal of Experimental Biology
Daniel Garcia Párraga, Michael Moore, Andreas Fahlman
Hydrostatic lung compression in diving marine mammals, with collapsing alveoli blocking gas exchange at depth, has been the main theoretical basis for limiting N2 uptake and avoiding gas emboli (GE) as they ascend. However, studies of beached and bycaught cetaceans and sea turtles imply that air-breathing marine vertebrates may, under unusual circumstances, develop GE that result in decompression sickness (DCS) symptoms. Theoretical modelling of tissue and blood gas dynamics of breath-hold divers suggests that changes in perfusion and blood flow distribution may also play a significant role...
April 25, 2018: Proceedings. Biological Sciences
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