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Garcia-Parraga D, Crespo-Picazo JL, Sterba-Boatwright B, Marco V, Muñoz-Baquero M, Robinson NJ, Stacy B, Fahlman A. New insights into risk variables associated with gas embolism in loggerhead sea turtles ( Caretta caretta) caught in trawls and gillnets. CONSERVATION PHYSIOLOGY 2023; 11:coad048. [PMID: 37425482 PMCID: PMC10326834 DOI: 10.1093/conphys/coad048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 06/02/2023] [Accepted: 06/26/2023] [Indexed: 07/11/2023]
Abstract
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. In addition, trawl depth and the GE score together explained the probability of mortality (P[mortality]) following recompression therapy. Specifically, a turtle with a GE score of 3 caught in a trawl deployed at 110 m had a P[mortality] of ~50%. For turtles caught in gillnets, no risk variables were significantly correlated with either the P[GE] or GE score. However, gillnet depth or GE score, separately, explained P[mortality], and a turtle caught at 45 m or with a GE score between 3 and 4 had a P[mortality] of 50%. Differences in the fishery characteristics precluded direct comparison of GE risk and mortality between these gear types. Although P[mortality] is expected to be significantly higher in untreated turtles released at sea, our findings can improve estimates of sea turtle mortality associated with trawls and gillnets, and help guide associate conservation efforts.
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Affiliation(s)
- Daniel Garcia-Parraga
- Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain
| | - Jose Luis Crespo-Picazo
- Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain
| | | | - Vicente Marco
- Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain
| | - Marta Muñoz-Baquero
- Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain
| | - Nathan J Robinson
- Fundación Oceanogràfic de la Comunitat Valenciana, Gran Vía Marqués del Turia 19, 46005 Valencia, Spain
- Institut de Ciències del Mar, Spanish National Research Council - Consejo Superior de Investigaciones Científicas, Barcelona 08003, Spain
| | - Brian Stacy
- National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Protected Resources, University of Florida (Duty Station), PO Box 110885, 2187 Mowry Road, Gainesville, FL 32611, USA
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Stimulating fermentation by the prolonged acceleration of gut transit protects against decompression sickness. Sci Rep 2018; 8:10128. [PMID: 29973647 PMCID: PMC6031626 DOI: 10.1038/s41598-018-28510-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 06/21/2018] [Indexed: 01/23/2023] Open
Abstract
Massive bubble formation after diving can lead to decompression sickness (DCS). Gut fermentation at the time of a dive exacerbates DCS due to endogenous hydrogen production. We sought to investigate whether medium-term stimulation of fermentation as a result of polyethylene glycol (PEG)-induced acceleration of bowel transit before diving exacerbates DCS in rats. Seven days before an experimental dry dive, 60 rats were randomly divided in two groups: an experimental group treated with PEG (n = 30) and an untreated control group (n = 30). Exhaled hydrogen was measured before the dive. Following hyperbaric exposure, we assessed for signs of DCS. After anaesthetisation, arterial blood was drawn to assay inflammatory cytokines and markers of oxidative stress. PEG led to a significant increase in exhaled H2 (35 ppm [10–73] compared with control 7 ppm [2–15]; p = 0.001). The probability of death was reduced in PEG-treated rats (PEG: 17% [95% CI 4–41] vs control: 50% [95% CI 26–74]; p = 0.034). In addition, inflammatory markers were reduced, and the antioxidant activity of glutathione peroxidase was significantly increased (529.2 U.l−1 [485.4–569.0] versus 366.4 U.l−1 [317.6–414.8]; p = 0.004). Thus, gut fermentation might have a positive effect on DCS. The antioxidant and neuroprotective properties of the fermentation by-products H2 and butyrate may explain these results.
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Allometric scaling of decompression sickness risk in terrestrial mammals; cardiac output explains risk of decompression sickness. Sci Rep 2017; 7:40918. [PMID: 28150725 PMCID: PMC5288729 DOI: 10.1038/srep40918] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 12/12/2016] [Indexed: 11/29/2022] Open
Abstract
A probabilistic model was used to predict decompression sickness (DCS) outcome in pig (70 and 20 kg), hamster (100 g), rat (220 g) and mouse (20 g) following air saturation dives. The data set included 179 pig, 200 hamster, 360 rat, and 224 mouse exposures to saturation pressures ranging from 1.9–15.2 ATA and with varying decompression rates (0.9–156 ATA • min−1). Single exponential kinetics described the tissue partial pressures (Ptiss) of N2: Ptiss = ∫(Pamb – Ptiss) • τ−1 dt, where Pamb is ambient N2 pressure and τ is a time constant. The probability of DCS [P(DCS)] was predicted from the risk function: P(DCS) = 1−e−r, where r = ∫(PtissN2 − Thr − Pamb) • Pamb–1 dt, and Thr is a threshold parameter. An equation that scaled τ with body mass included a constant (c) and an allometric scaling parameter (n), and the best model included n, Thr, and two c. The final model provided accurate predictions for 58 out of 61 dive profiles for pig, hamster, rat, and mouse. Thus, body mass helped improve the prediction of DCS risk in four mammalian species over a body mass range covering 3 orders of magnitude.
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Updating a gas dynamics model using estimates for California sea lions (Zalophus californianus). Respir Physiol Neurobiol 2016; 234:1-8. [PMID: 27562522 DOI: 10.1016/j.resp.2016.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 07/24/2016] [Accepted: 08/21/2016] [Indexed: 11/22/2022]
Abstract
Theoretical models are used to predict how breath-hold diving vertebrates manage O2, CO2, and N2 while underwater. One recent gas dynamics model used available lung and tracheal compliance data from various species. As variation in respiratory compliance significantly affects alveolar compression and pulmonary shunt, the current study objective was to evaluate changes in model output when using species-specific parameters from California sea lions (Zalophus californianus). We explored the effects of lung and dead space compliance on the uptake of N2, O2, and CO2 in various tissues during a series of hypothetical dives. The updated parameters allowed for increased compliance of the lungs and an increased stiffness in the trachea. When comparing updated model output with a model using previous compliance values, there was a large decrease in N2 uptake but little change in O2 and CO2 levels. Therefore, previous models may overestimate N2 tensions and the risk of gas-related disease, such as decompression sickness (DCS), in marine mammals.
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Colonic Fermentation Promotes Decompression sickness in Rats. Sci Rep 2016; 6:20379. [PMID: 26853722 PMCID: PMC4745042 DOI: 10.1038/srep20379] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 12/31/2015] [Indexed: 01/31/2023] Open
Abstract
Massive bubble formation after diving can lead to decompression sickness (DCS). During dives with hydrogen as a diluent for oxygen, decreasing the body’s H2 burden by inoculating hydrogen-metabolizing microbes into the gut reduces the risk of DCS. So we set out to investigate if colonic fermentation leading to endogenous hydrogen production promotes DCS in fasting rats. Four hours before an experimental dive, 93 fasting rats were force-fed, half of them with mannitol and the other half with water. Exhaled hydrogen was measured before and after force-feeding. Following the hyperbaric exposure, we looked for signs of DCS. A higher incidence of DCS was found in rats force-fed with mannitol than in those force-fed with water (80%, [95%CI 56, 94] versus 40%, [95%CI 19, 64], p < 0.01). In rats force-fed with mannitol, metronidazole pretreatment reduced the incidence of DCS (33%, [95%CI 15, 57], p = 0.005) at the same time as it inhibited colonic fermentation (14 ± 35 ppm versus 118 ± 90 ppm, p = 0.0001). Pre-diveingestion of mannitol increased the incidence of DCS in fasting rats when colonic fermentation peaked during the decompression phase. More generally, colonic fermentation in rats on a normal diet could promote DCS through endogenous hydrogen production.
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Fahlman A, Moore MJ, Trites AW, Rosen DAS, Haulena M, Waller N, Neale T, Yang M, Thom SR. Dive, food, and exercise effects on blood microparticles in Steller sea lions (Eumetopias jubatus): exploring a biomarker for decompression sickness. Am J Physiol Regul Integr Comp Physiol 2016; 310:R596-601. [PMID: 26843583 DOI: 10.1152/ajpregu.00512.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/01/2016] [Indexed: 11/22/2022]
Abstract
Recent studies of stranded marine mammals indicate that exposure to underwater military sonar may induce pathophysiological responses consistent with decompression sickness (DCS). However, DCS has been difficult to diagnose in marine mammals. We investigated whether blood microparticles (MPs, measured as number/μl plasma), which increase in response to decompression stress in terrestrial mammals, are a suitable biomarker for DCS in marine mammals. We obtained blood samples from trained Steller sea lions (Eumetopias jubatus, 4 adult females) wearing time-depth recorders that dove to predetermined depths (either 5 or 50 meters). We hypothesized that MPs would be positively related to decompression stress (depth and duration underwater). We also tested the effect of feeding and exercise in isolation on MPs using the same blood sampling protocol. We found that feeding and exercise had no effect on blood MP levels, but that diving caused MPs to increase. However, blood MP levels did not correlate with diving depth, relative time underwater, and presumed decompression stress, possibly indicating acclimation following repeated exposure to depth.
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Affiliation(s)
- Andreas Fahlman
- Texas A&M University, Corpus Christi, Texas; Oceanografíc Research Department, C/ Eduardo Primo Yúfera 1B, Valencia, Spain
| | - Michael J Moore
- Woods Hole Oceanographic Institution, Woods Hole, Massachusetts
| | - Andrew W Trites
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, British Columbia, Canada
| | - David A S Rosen
- Marine Mammal Research Unit, Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, British Columbia, Canada
| | - Martin Haulena
- Vancouver Aquarium, Vancouver, British Columbia, Canada; and
| | - Nigel Waller
- Vancouver Aquarium, Vancouver, British Columbia, Canada; and
| | - Troy Neale
- Vancouver Aquarium, Vancouver, British Columbia, Canada; and
| | - Ming Yang
- Department of Emergency Medicine, University of Maryland, Baltimore, Maryland; and
| | - Stephen R Thom
- Department of Emergency Medicine, University of Maryland, Baltimore, Maryland; and
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Fahlman A, Loring SH, Levine G, Rocho-Levine J, Austin T, Brodsky M. Lung mechanics and pulmonary function testing in cetaceans. J Exp Biol 2015; 218:2030-8. [DOI: 10.1242/jeb.119149] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
We measured esophageal pressures, respiratory flow rates, and expired O2 and CO2 in six adult bottlenose dolphins (Tursiops truncatus) during voluntary breaths and maximal (chuff) respiratory efforts. The data were used to estimate the dynamic specific lung compliance (sCL), the O2 consumption rate (V̇O2) and CO2 production rates (V̇CO2) during rest. Our results indicate that bottlenose dolphins have the capacity to generate respiratory flow rates that exceed 130 l s−1 and 30 l s−1 during expiration and inspiration, respectively. The esophageal pressures indicated that expiration is passive during voluntary breaths, but active during maximal efforts, whereas inspiration is active for all breaths. The average sCL of dolphins was 0.31±0.04 cmH2O−1, which is considerably higher than that of humans (0.08 cmH2O−1) and that previously measured in a pilot whale (0.13 cmH2O−1). The average estimated V̇O2 and V̇CO2 using our breath-by-breath respirometry system ranged from 0.857 to 1.185 l O2 min−1 and 0.589 to 0.851 l CO2 min−1, respectively, which is similar to previously published metabolic measurements from the same animals using conventional flow-through respirometry. In addition, our custom-made system allows us to approximate end tidal gas composition. Our measurements provide novel data for respiratory physiology in cetaceans, which may be important for clinical medicine and conservation efforts.
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Affiliation(s)
- Andreas Fahlman
- Department of Life Science, Texas A&M University-Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA
| | - Stephen H. Loring
- Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Gregg Levine
- Dolphin Quest, Oahu, 5000 Kahala Ave, Honolulu, HI 96816, USA
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Lemaitre F, Fahlman A, Gardette B, Kohshi K. Decompression sickness in breath-hold divers: A review. J Sports Sci 2009; 27:1519-34. [DOI: 10.1080/02640410903121351] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Could beaked whales get the bends? Respir Physiol Neurobiol 2009; 167:235-46. [DOI: 10.1016/j.resp.2009.04.023] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Revised: 04/28/2009] [Accepted: 04/30/2009] [Indexed: 11/23/2022]
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Mahon RT, Dainer HM, Gibellato MG, Soutiere SE. Short oxygen prebreathe periods reduce or prevent severe decompression sickness in a 70-kg swine saturation model. J Appl Physiol (1985) 2009; 106:1459-63. [PMID: 19179650 DOI: 10.1152/japplphysiol.91058.2008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Disabled submarine (DISSUB) survivors are expected to achieve saturation with inert gas. However, rescue procedures may not accommodate staged decompression, raising the potential for severe decompression sickness (DCS). Alternatives to standard recompression therapy are needed. It has been demonstrated in humans that isobaric oxygen "prebreathing" (OPB) can accelerate decompression in a DISSUB scenario. In-70 kg swine saturated at 2.82 atm absolute (ATA), 1 h of OPB eliminated death and reduced severe DCS. We hypothesized that even shorter periods (<1 h) of OPB before no-stop decompression from saturation at 2.82 ATA could reduce the incidence of DCS in a large animal model. Catheterized Yorkshire swine (68.8 +/- 1.7 kg) in individual Plexiglas boxes within a large animal hyperbaric chamber were compressed to 2.82 ATA for 22 h. Following saturation and while still at depth, breathing gas was switched to >95% O(2) for 45 min (OPB(45)), 15 min (OPB(15)), or 5 min (OPB(05)) of OPB, or no OPB (control). The chamber was then decompressed without stops (0.91 ATA/min). Observers then entered the chamber and recorded signs of DCS for 2 h. All OPB periods significantly reduced the risk of developing type II DCS. OPB(45) eliminated severe DCS. Controls had a 2.5 times greater risk of developing type II DCS than OPB(05) (P = 0.016). OPB(45) and OPB(15) significantly reduced type I DCS compared with controls. These results support the potential of OPB as an alternative to staged decompression and that OPB could be expected to improve outcome in a DISSUB rescue scenario.
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Affiliation(s)
- R T Mahon
- Naval Medical Research Center, Undersea Medicine Department, 503 Robert Grant Ave., Silver Spring, MD 20910-7500, USA.
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Fahlman A, Schmidt A, Jones DR, Bostrom BL, Handrich Y. To what extent might N2 limit dive performance in king penguins? ACTA ACUST UNITED AC 2007; 210:3344-55. [PMID: 17872988 DOI: 10.1242/jeb.008730] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A mathematical model was used to explore if elevated levels of N2, and risk of decompression sickness (DCS), could limit dive performance (duration and depth) in king penguins (Aptenodytes patagonicus). The model allowed prediction of blood and tissue (central circulation, muscle, brain and fat) N2 tensions (P(N2)) based on different cardiac outputs and blood flow distributions. Estimated mixed venous P(N2) agreed with values observed during forced dives in a compression chamber used to validate the assumptions of the model. During bouts of foraging dives, estimated mixed venous and tissue P(N2) increased as the bout progressed. Estimated mean maximum mixed venous P(N2) upon return to the surface after a dive was 4.56+/-0.18 atmospheres absolute (ATA; range: 4.37-4.78 ATA). This is equivalent to N2 levels causing a 50% DCS incidence in terrestrial animals of similar mass. Bout termination events were not associated with extreme mixed venous N2 levels. Fat P(N2) was positively correlated with bout duration and the highest estimated fat P(N2) occurred at the end of a dive bout. The model suggested that short and shallow dives occurring between dive bouts help to reduce supersaturation and thereby DCS risk. Furthermore, adipose tissue could also help reduce DCS risk during the first few dives in a bout by functioning as a sink to buffer extreme levels of N2.
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Affiliation(s)
- A Fahlman
- North Pacific Universities Marine Mammal Research Consortium, UBC Marine Mammal Research Unit, ROOM 247, AERL, 2202 Main Mall, Vancouver, BC, V6T 1Z4, Canada.
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Fahlman A, Olszowka A, Bostrom B, Jones DR. Deep diving mammals: Dive behavior and circulatory adjustments contribute to bends avoidance. Respir Physiol Neurobiol 2006; 153:66-77. [PMID: 16413835 DOI: 10.1016/j.resp.2005.09.014] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Revised: 09/01/2005] [Accepted: 09/06/2005] [Indexed: 10/25/2022]
Abstract
A mathematical model was created that predicted blood and tissue N(2) tension (P(N2)) during breath-hold diving. Measured muscle P(N2) from the bottlenose dolphin after diving repeatedly to 100 m (Tursiops truncatus [Ridgway and Howard, 1979, Science, 4423, 1182-1183]) was compared with predictions from the model. Lung collapse was modelled as a 100% pulmonary shunt which yielded tissue P(N2) similar to those reported for the dolphin. On the other hand, predicted muscle P(N2) for an animal with a dive response, reducing cardiac output by 66% from surface values (20.5 to 6.8l x min(-1)), also agreed well with observed values in the absence of lung collapse. In fact, modelling indicated that both cardiovascular adjustments and dive behaviour are important in reducing N2 uptake during diving and enhancing safe transfer of tissue and blood N2 back to the lung immediately before coming to the surface. In particular, diving bradycardia during the descent and bottom phase together with a reduced ascent rate and increase in heart rate reduced mixed venous P(N2) upon return to the surface by as much as 45%. This has important implications as small reductions in inert gas load (approximately 5%) can substantially reduce decompression sickness (DCS) risk by as much as 50% (Fahlman et al., 2001, J. Appl. Physiol. 91, 2720-2729).
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Affiliation(s)
- A Fahlman
- Department of Zoology, The University of British Columbia, 6270 University Blvd., Vancouver, BC, Canada V6T 1Z4.
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Fahlman A, Lin WC, Whitman WB, Kayar SR. Modulation of decompression sickness risk in pigs with caffeine during H(2) biochemical decompression. J Appl Physiol (1985) 2002; 93:1583-9. [PMID: 12381741 DOI: 10.1152/japplphysiol.00349.2002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In H(2) biochemical decompression, H(2)-metabolizing intestinal microbes remove gas stored in tissues of animals breathing hyperbaric H(2), thereby reducing decompression sickness (DCS) risk. We hypothesized that increasing intestinal perfusion in pigs would increase the activity of intestinal Methanobrevibacter smithii, lowering DCS incidence further. Pigs (Sus scrofa, 17-23 kg, n = 20) that ingested caffeine (5 mg/kg) increased O(2) consumption rate in 1 atm air by ~20% for at least 3 h. Pigs were given caffeine alone or caffeine plus injections of M. smithii. Animals were compressed to 24 atm (20.5-23.1 atm H(2), 0.3-0.5 atm O(2)) for 3 h, then decompressed and observed for signs of DCS. In previous studies, DCS incidence in animals without caffeine treatment was significantly (P < 0.05) lower with M. smithii injections (7/16) than in controls (9/10). However, contrary to our hypothesis, DCS incidence was marginally higher (P = 0.057) in animals that received caffeine and M. smithii (9/10) than in animals that received caffeine but no M. smithii (4/10). More information on gas kinetics is needed before extending H(2) biochemical decompression to humans.
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Affiliation(s)
- Andreas Fahlman
- Environmental Physiology Department, Naval Medical Research Center, Silver Spring, Maryland 20910-7500, USA
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