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Dugrenot E, Balestra C, Gouin E, L'Her E, Guerrero F. Physiological effects of mixed-gas deep sea dives using a closed-circuit rebreather: a field pilot study. Eur J Appl Physiol 2021; 121:3323-3331. [PMID: 34435274 DOI: 10.1007/s00421-021-04798-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 08/19/2021] [Indexed: 12/11/2022]
Abstract
PURPOSE Deep diving using mixed gas with closed-circuit rebreathers (CCRs) is increasingly common. However, data regarding the effects of these dives are still scarce. This preliminary field study aimed at evaluating the acute effects of deep (90-120 msw) mixed-gas CCR bounce dives on lung function in relation with other physiological parameters. METHODS Seven divers performed a total of sixteen open-sea CCR dives breathing gas mixture of helium, nitrogen and oxygen (trimix) within four days at 2 depths (90 and 120 msw). Spirometric parameters, SpO2, body mass, hematocrit, short term heart rate variability (HRV) and critical flicker fusion frequency (CFFF) were measured at rest 60 min before the dive and 120 min after surfacing. RESULTS The median [1st-3rd quartile] of the forced vital capacity was lower (84% [76-93] vs 91% [74-107] of predicted values; p = 0.029), whereas FEV1/FVC was higher (98% [95-99] vs 95% [89-99]; p = 0.019) after than before the dives. The other spirometry values and SpO2 were unchanged. Body mass decreased from 73.5 kg (72.0-89.6) before the dives to 70.0 kg (69.2-85.8) after surfacing (p = 0.001), with no change of hematocrit or CFFT. HRV was increased as indicated by the higher SDNN, RMSSD and pNN50 after than before dives. CONCLUSION The present observation represents the first original data regarding the effects of deep repeated CCR dives. The body mass loss and decrease of FVC after bounce dives at depth of about 100 msw may possibly impose an important physiological stress for the divers.
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Affiliation(s)
- Emmanuel Dugrenot
- TEK diving SAS, F-29200, Brest, France
- Univ Brest, ORPHY, IBSAM, 6 avenue Le Gorgeu, F-29200, Brest, France
| | - Costantino Balestra
- Environmental and Occupational Physiology Laboratory, (ISEK), Haute Ecole Bruxelles-Brabant (HE2B), 1160, Brussels, Belgium
| | | | - Erwan L'Her
- Médecine Intensive et Réanimation, CHRU de Brest, Brest, NA, France
| | - François Guerrero
- Univ Brest, ORPHY, IBSAM, 6 avenue Le Gorgeu, F-29200, Brest, France.
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Lafère P, Lambrechts K, Germonpré P, Balestra A, Germonpré FL, Marroni A, Cialoni D, Bosco G, Balestra C. Heart Rate Variability During a Standard Dive: A Role for Inspired Oxygen Pressure? Front Physiol 2021; 12:635132. [PMID: 34381372 PMCID: PMC8350129 DOI: 10.3389/fphys.2021.635132] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 06/18/2021] [Indexed: 01/02/2023] Open
Abstract
Introduction: Heart rate variability (HRV) during underwater diving has been infrequently investigated because of environment limitations and technical challenges. This study aims to analyze HRV changes while diving at variable hyperoxia when using open circuit (OC) air diving apparatus or at constant hyperoxia using a closed-circuit rebreather (CCR). We used HRV analysis in time and frequency domain adding nonlinear analysis which is more adapted to short-time analysis and less dependent on respiratory rate (Sinus respiratory arrhythmia). Materials and Methods: 18 males, 12 using OC (30 mfw for 20 min) and 6 using CCR (30 mfw for 40 min.). HRV was recorded using a polar recorder. Four samples of R-R intervals representing the dive were saved for HRV analysis. Standard deviation of normal-to-normal intervals (SDNN), square root of the mean squared differences between successive RR intervals (rMSSD), and average RR intervals (RR) in time-domain; low frequency (LF) and high frequency (HF) in frequency domain were investigated. Nonlinear analysis included fractal dimension (FrD). Results: SDNN and rMSSD were significantly increased during descent and at depth with OC, not with CCR. Mean RR interval was longer at depth with OC, but only during ascent and after the dive with CCR. HF power was higher than baseline during the descent both with OC and CCR and remained elevated at depth for OC. The LF/HF ratio was significantly lower than baseline for descent and at depth with both OC and CCR. After 30 min of recovery, the LF/HF ratio was higher than baseline with both OC and CCR. Nonlinear analysis detected differences at depth for OC and CCR. Discussion: Increased parasympathetic tone was present during diving. RR duration, SDNN; rMSSD, HF spectral power all increased during the dive above pre-dive levels. Conversely, HF power decreased (and the LF/HF increased) 30 min after the dive. Using FrD, a difference was detected between OC and CCR, which may be related to differences in partial pressure of oxygen breathed during the dive.
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Affiliation(s)
- Pierre Lafère
- Environmental, Occupational & Ageing Physiology Laboratory, Haute Ecole Bruxelles-Brabant, Brussels, Belgium.,DAN Europe Research Division, Roseto degli Abruzzi, Italy.,Laboratoire ORPHY, EA4324, Université de Bretagne Occidentale, Brest, France
| | - Kate Lambrechts
- Environmental, Occupational & Ageing Physiology Laboratory, Haute Ecole Bruxelles-Brabant, Brussels, Belgium
| | - Peter Germonpré
- Environmental, Occupational & Ageing Physiology Laboratory, Haute Ecole Bruxelles-Brabant, Brussels, Belgium.,DAN Europe Research Division, Roseto degli Abruzzi, Italy.,Centre for Hyperbaric Oxygen Therapy, Military Hospital "Queen Astrid", Brussels, Belgium
| | - Ambre Balestra
- Environmental, Occupational & Ageing Physiology Laboratory, Haute Ecole Bruxelles-Brabant, Brussels, Belgium
| | - Faye Lisa Germonpré
- Centre for Hyperbaric Oxygen Therapy, Military Hospital "Queen Astrid", Brussels, Belgium
| | | | - Danilo Cialoni
- DAN Europe Research Division, Roseto degli Abruzzi, Italy.,Environmental Physiology and Medicine Laboratory, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Gerardo Bosco
- Environmental Physiology and Medicine Laboratory, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Costantino Balestra
- Environmental, Occupational & Ageing Physiology Laboratory, Haute Ecole Bruxelles-Brabant, Brussels, Belgium.,DAN Europe Research Division, Roseto degli Abruzzi, Italy.,Physical Activity Teaching Unit, Motor Sciences Department, Université Libre de Bruxelles (ULB), Brussels, Belgium
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Lundell RV, Tuominen L, Ojanen T, Parkkola K, Räisänen-Sokolowski A. Diving Responses in Experienced Rebreather Divers: Short-Term Heart Rate Variability in Cold Water Diving. Front Physiol 2021; 12:649319. [PMID: 33897457 PMCID: PMC8058382 DOI: 10.3389/fphys.2021.649319] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 03/16/2021] [Indexed: 11/13/2022] Open
Abstract
Introduction Technical diving is very popular in Finland throughout the year despite diving conditions being challenging, especially due to arctic water and poor visibility. Cold water, immersion, submersion, hyperoxia, as well as psychological and physiological stress, all have an effect on the autonomic nervous system (ANS). Materials and methods To evaluate divers' ANS responses, short-term (5 min) heart rate variability (HRV) during dives in 2-4°C water was measured. HRV resting values were evaluated from separate measurements before and after the dives. Twenty-six experienced closed circuit rebreather (CCR) divers performed an identical 45-meter decompression dive with a non-physical task requiring concentration at the bottom depth. Results Activity of the ANS branches was evaluated with the parasympathetic (PNS) and sympathetic (SNS) indexes of the Kubios HRV Standard program. Compared to resting values, PNS activity decreased significantly on immersion with face out of water. From immersion, it increased significantly with facial immersion, just before decompression and just before surfacing. Compared to resting values, SNS activity increased significantly on immersion with face out of water. Face in water and submersion measures did not differ from the immersion measure. After these measurements, SNS activity decreased significantly over time. Conclusion Our study indicates that the trigeminocardiac part of the diving reflex causes the strong initial PNS activation at the beginning of the dive but the reaction seems to decrease quickly. After this initial activation, cold seemed to be the most prominent promoter of PNS activity - not pressure. Also, our study showed a concurrent increase in both SNS and PNS branches, which has been associated with an elevated risk for arrhythmia. Therefore, we recommend a short adaptation phase at the beginning of cold-water diving before physical activity.
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Affiliation(s)
| | - Laura Tuominen
- Department of Anaestesia, Tampere University Hospital, Tampere, Finland
| | - Tommi Ojanen
- Finnish Defence Research Agency, Finnish Defence Forces, Tuusula, Finland
| | - Kai Parkkola
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland.,Department of Leadership and Military Pedagogy, National Defence University, Helsinki, Finland
| | - Anne Räisänen-Sokolowski
- Diving Medical Centre, Finnish Defence Forces, Helsinki, Finland.,Department of Pathology, Helsinki University Hospital, and University of Helsinki, Helsinki, Finland
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