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Sherif HM, Albalooshi YM, Al Hashemi A, Feteaha I, Ismail FH, Zaki MK. The use of dive computers in forensic investigations of fatal breath-hold diving accidents: a case study. Forensic Sci Med Pathol 2024; 20:636-643. [PMID: 37648957 DOI: 10.1007/s12024-023-00700-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/16/2023] [Indexed: 09/01/2023]
Abstract
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. With the deceased diver's dive computer, we concluded that a shallow water blackout caused him to drown. Data from the dive computer were extracted, graphed, and analysed to explain how a skilled swimmer and diver drowned on one of his seemingly ordinary diving trips. The dive computer can be the sole witness to a fatal dive event and provide invaluable information to forensic scientists since the diver is almost always alone. To our knowledge of the available literature, dive computers have been used in scuba diving fatality investigations; however, we believe that they have not been used in death investigations of breath-hold divers. Deficient or hasty conclusions are often based solely on autopsy findings without data collected by diving technicians and investigators. It is crucial to wait to draw conclusions until all possible dive information has been gathered and studied. This study discusses the deficiency in presenting a reasonable idea to the grieving family and friends of how their beloved relative could have drowned even though he was known to be a fit and skilled diver and avid swimmer.
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Affiliation(s)
- Hazem M Sherif
- Forensic Medicine Department, General Department of Forensic Science and Criminology, Dubai Police, GHQ, Dubai, United Arab Emirates
| | - Younis M Albalooshi
- Forensic Medicine Department, General Department of Forensic Science and Criminology, Dubai Police, GHQ, Dubai, United Arab Emirates
| | - Ahmad Al Hashemi
- Forensic Medicine Department, General Department of Forensic Science and Criminology, Dubai Police, GHQ, Dubai, United Arab Emirates
| | - Islam Feteaha
- Forensic Medicine Department, General Department of Forensic Science and Criminology, Dubai Police, GHQ, Dubai, United Arab Emirates
| | - Farha H Ismail
- Medical Laboratory Sciences, University of Minnesota, Minneapolis, USA
| | - Mamdouh Kamal Zaki
- Forensic Medicine Administration, Forensic Medicine Services Center, Taif, Makkah Region, Saudi Arabia.
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Mulder E, Staunton C, Sieber A, Schagatay E. Unlocking the depths: multiple factors contribute to risk for hypoxic blackout during deep freediving. Eur J Appl Physiol 2023; 123:2483-2493. [PMID: 37300699 PMCID: PMC10615935 DOI: 10.1007/s00421-023-05250-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 06/01/2023] [Indexed: 06/12/2023]
Abstract
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. RESULTS Mean ± SD depth was 53 ± 14 m for deep and 17 ± 4 m for shallow dives. Respective dive durations (120 ± 18 s and 116 ± 43 s) did not differ. Deep dives resulted in lower minimum SpO2 (58 ± 17%) compared with shallow dives (74 ± 17%; P = 0.029). Overall diving HR was 7 bpm higher in deep dives (P = 0.002) although minimum HR was similar in both types of dives (39 bpm). Three divers desaturated early at depth, of which two exhibited severe hypoxia (SpO2 ≤ 65%) upon resurfacing. Additionally, four divers developed severe hypoxia after dives. CONCLUSIONS Despite similar dive durations, oxygen desaturation was greater during deep dives, confirming increased risk of hypoxic blackout with increased depth. In addition to the rapid drop in alveolar pressure and oxygen uptake during ascent, several other risk factors associated with deep freediving were identified, including higher swimming effort and oxygen consumption, a compromised diving response, an autonomic conflict possibly causing arrhythmias, and compromised oxygen uptake at depth by lung compression possibly leading to atelectasis or pulmonary edema in some individuals. Individuals with elevated risk could likely be identified using wearable technology.
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Affiliation(s)
- Eric Mulder
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Kunskapens Väg 8, 831 25, Östersund, Sweden.
| | - Craig Staunton
- Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
| | - Arne Sieber
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Kunskapens Väg 8, 831 25, Östersund, Sweden
- Oxygen Scientific GmbH, Graz, Austria
| | - Erika Schagatay
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Kunskapens Väg 8, 831 25, Östersund, Sweden
- Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
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Mulder E, Sieber A, McKnight C, Schagatay E. Underwater pulse oximetry reveals increased rate of arterial oxygen desaturation across repeated freedives to 11 metres of freshwater. Diving Hyperb Med 2023; 53:16-23. [PMID: 36966518 PMCID: PMC10318178 DOI: 10.28920/dhm53.1.16-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 11/26/2022] [Indexed: 03/29/2023]
Abstract
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). RESULTS Median dive durations were 54.0 s, 103.0 s and 75.5 s (all dives median 81.5 s). Median baseline HR was 76.0 beats per minute (bpm), which decreased during dives to 48.0 bpm in dive one, 40.5 bpm in dive two and 48.5 bpm in dive three (all P < 0.05 from baseline). Median pre-dive baseline SpO2 was 99.5%. SpO2 remained similar to baseline for the first half of the dives, after which the rate of desaturation increased during the second half of the dives with each subsequent dive. Lowest median SpO2 after dive one was 97.0%, after dive two 83.5% (P < 0.05 from baseline) and after dive three 82.5% (P < 0.01 from baseline). SpO2 had returned to baseline within 20 s after all dives. CONCLUSIONS We speculate that the enhanced rate of arterial oxygen desaturation across the serial dives may be attributed to a remaining 'oxygen debt', leading to progressively increased oxygen extraction by desaturated muscles. Despite being twice the dive duration, the recovery period may be too short to allow full recovery and to sustain prolonged serial diving, thus does not guarantee safe diving.
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Affiliation(s)
- Eric Mulder
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
- Corresponding author: Eric Mulder, Mid Sweden University, Kunskapens väg 8, 83125 Östersund, Sweden
| | - Arne Sieber
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
- OXYGEN Scientific GmbH, Feldkirchen, Austria
| | - Chris McKnight
- Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Scotland
| | - Erika Schagatay
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
- Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
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Dolscheid-Pommerich RC, Stoffel-Wagner B, Fimmers R, Eichhorn L. Changes in hormones after apneic hypoxia/hypercapnia - an investigation in voluntary apnea divers. Respir Physiol Neurobiol 2022; 298:103845. [PMID: 35041989 DOI: 10.1016/j.resp.2022.103845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/11/2022] [Accepted: 01/13/2022] [Indexed: 10/19/2022]
Abstract
BACKGROUND Prolonged apnea is characterized by hypoxia/hypercapnia. Hypoxia can be associated with hormonal dysfunction. We raised the question as to whether steroid hormonal and gonadotropin levels could be influenced by short-term hypoxia/hypercapnia in a model of dry apnea in trained apnea divers. METHODS Adrenal, sex steroid and pituitary hormones were measured in ten trained voluntary apnea divers before, immediately after, 0.5 h and 4 h after a maximal breath-hold. Apnea was carried out under dry conditions. RESULTS Corticosterone, progesterone, cortisol, 17-OH-progesterone, dehydroepiandrosterone and androstenedione showed a significant continuous increase with a maximum at 0.5 h after apnea, followed by a decrease back to or below baseline at 4 h after apnea. Testosterone, estradiol, cortisone and dihydrotestosterone showed a decrease 4 h after apnea. Dehydroepiandrosteronesulfate, luteinizing hormone (LH) and follicle stimulating hormone (FSH) showed no significant changes. CONCLUSION Even a single apnea resulted in two different patterns of hormone response to apnea, with increased adrenal and reduced sex steroid levels, while LH/FSH showed no clear kinetic reaction. Apnea divers might be a suitable clinical model for hypoxic disease.
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Affiliation(s)
- R C Dolscheid-Pommerich
- Department of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany.
| | - B Stoffel-Wagner
- Department of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany
| | - R Fimmers
- Institute for Medical Biometry, Informatics and Epidemiology, University Hospital Bonn, Bonn, Germany
| | - L Eichhorn
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany
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Patrician A, Dujić Ž, Spajić B, Drviš I, Ainslie PN. Breath-Hold Diving - The Physiology of Diving Deep and Returning. Front Physiol 2021; 12:639377. [PMID: 34093221 PMCID: PMC8176094 DOI: 10.3389/fphys.2021.639377] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/07/2021] [Indexed: 11/13/2022] Open
Abstract
Breath-hold diving involves highly integrative physiology and extreme responses to both exercise and asphyxia during progressive elevations in hydrostatic pressure. With astonishing depth records exceeding 100 m, and up to 214 m on a single breath, the human capacity for deep breath-hold diving continues to refute expectations. The physiological challenges and responses occurring during a deep dive highlight the coordinated interplay of oxygen conservation, exercise economy, and hyperbaric management. In this review, the physiology of deep diving is portrayed as it occurs across the phases of a dive: the first 20 m; passive descent; maximal depth; ascent; last 10 m, and surfacing. The acute risks of diving (i.e., pulmonary barotrauma, nitrogen narcosis, and decompression sickness) and the potential long-term medical consequences to breath-hold diving are summarized, and an emphasis on future areas of research of this unique field of physiological adaptation are provided.
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Affiliation(s)
- Alexander Patrician
- Center for Heart, Lung & Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Željko Dujić
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Boris Spajić
- Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia
| | - Ivan Drviš
- Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia
| | - Philip N Ainslie
- Center for Heart, Lung & Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
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Mulder E, Schagatay E, Sieber A. First Evaluation of a Newly Constructed Underwater Pulse Oximeter for Use in Breath-Holding Activities. Front Physiol 2021; 12:649674. [PMID: 33981249 PMCID: PMC8107719 DOI: 10.3389/fphys.2021.649674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 03/30/2021] [Indexed: 11/17/2022] Open
Abstract
Studying risk factors in freediving, such as hypoxic blackout, requires development of new methods to enable remote underwater monitoring of physiological variables. We aimed to construct and evaluate a new water- and pressure proof pulse oximeter for use in freediving research. The study consisted of three parts: (I) A submersible pulse oximeter (SUB) was developed on a ruggedized platform for recording of physiological parameters in challenging environments. Two MAX30102 sensors were used to record plethysmograms, and included red and infra-red emitters, diode drivers, photodiode, photodiode amplifier, analog to digital converter, and controller. (II) We equipped 20 volunteers with two transmission pulse oximeters (TPULS) and SUB to the fingers. Arterial oxygen saturation (SpO2) and heart rate (HR) were recorded, while breathing room air (21% O2) and subsequently a hypoxic gas (10.7% O2) at rest in dry conditions. Bland-Altman analysis was used to evaluate bias and precision of SUB relative to SpO2 values from TPULS. (III) Six freedivers were monitored with one TPULS and SUB placed at the forehead, during a maximal effort immersed static apnea. For dry baseline measurements (n = 20), SpO2 bias ranged between −0.8 and −0.6%, precision between 1.0 and 1.5%; HR bias ranged between 1.1 and 1.0 bpm, precision between 1.4 and 1.9 bpm. For the hypoxic episode, SpO2 bias ranged between −2.5 and −3.6%, precision between 3.6 and 3.7%; HR bias ranged between 1.4 and 1.9 bpm, precision between 2.0 and 2.1 bpm. Freedivers (n = 6) performed an apnea of 184 ± 53 s. Desaturation- and resaturation response time of SpO2 was approximately 15 and 12 s shorter in SUB compared to TPULS, respectively. Lowest SpO2 values were 76 ± 10% for TPULS and 74 ± 13% for SUB. HR traces for both pulse oximeters showed similar patterns. For static apneas, dropout rate was larger for SUB (18%) than for TPULS (<1%). SUB produced similar SpO2 and HR values as TPULS, both during normoxic and hypoxic breathing (n = 20), and submersed static apneas (n = 6). SUB responds more quickly to changes in oxygen saturation when sensors were placed at the forehead. Further development of SUB is needed to limit signal loss, and its function should be tested at greater depth and lower saturation.
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Affiliation(s)
- Eric Mulder
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Erika Schagatay
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden.,Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
| | - Arne Sieber
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
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Mulder E, Sieber A, Schagatay E. Using Underwater Pulse Oximetry in Freediving to Extreme Depths to Study Risk of Hypoxic Blackout and Diving Response Phases. Front Physiol 2021; 12:651128. [PMID: 33868018 PMCID: PMC8047056 DOI: 10.3389/fphys.2021.651128] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/15/2021] [Indexed: 11/13/2022] Open
Abstract
Deep freediving exposes humans to hypoxia and dramatic changes in pressure. The effect of depth on gas exchange may enhance risk of hypoxic blackout (BO) during the last part of the ascent. Our aim was to investigate arterial oxygen saturation (SpO2) and heart rate (HR) in shallow and deep freedives, central variables, which have rarely been studied underwater in deep freediving. Four male elite competitive freedivers volunteered to wear a newly developed underwater pulse oximeter for continuous monitoring of SpO2 and HR during self-initiated training in the sea. Two probes were placed on the temples, connected to a recording unit on the back of the freediver. Divers performed one "shallow" and one "deep" constant weight dive with fins. Plethysmograms were recorded at 30 Hz, and SpO2 and HR were extracted. Mean ± SD depth of shallow dives was 19 ± 3 m, and 73 ± 12 m for deep dives. Duration was 82 ± 36 s in shallow and 150 ± 27 s in deep dives. All divers desaturated more during deeper dives (nadir 55 ± 10%) compared to shallow dives (nadir 80 ± 22%) with a lowest SpO2 of 44% in one deep dive. HR showed a "diving response," with similar lowest HR of 42 bpm in shallow and deep dives; the lowest value (28 bpm) was observed in one shallow dive. HR increased before dives, followed by a decline, and upon resurfacing a peak after which HR normalized. During deep dives, HR was influenced by the level of exertion across different diving phases; after an initial drop, a second HR decline occurred during the passive "free fall" phase. The underwater pulse oximeter allowed successful SpO2 and HR monitoring in freedives to 82 m depth - deeper than ever recorded before. Divers' enhanced desaturation during deep dives was likely related to increased exertion and extended duration, but the rapid extreme desaturation to below 50% near surfacing could result from the diminishing pressure, in line with the hypothesis that risk of hypoxic BO may increase during ascent. Recordings also indicated that the diving response is not powerful enough to fully override the exercise-induced tachycardia during active swimming. Pulse oximetry monitoring of essential variables underwater may be an important step to increase freediving safety.
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Affiliation(s)
- Eric Mulder
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Arne Sieber
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
| | - Erika Schagatay
- Environmental Physiology Group, Department of Health Sciences, Mid Sweden University, Östersund, Sweden
- Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, Sweden
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