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Increased Risk of Decompression Sickness When Diving With a Right-to-Left Shunt: Results of a Prospective Single-Blinded Observational Study (The “Carotid Doppler” Study)

ABSTRACT: Introduction: Divers with a patent Foramen Ovale (PFO) have an increased risk for decompression sickness (DCS) when diving with compressed breathing gas. The relative risk increase, however, is difficult to establish as the PFO status of divers is usually only determined after a DCS occurrence. Methods: This prospective, single-blinded, observational study was designed to collect DCS data from volunteer divers after screening for right-to-left shunt (RLS) using a Carotid Doppler test. Divers were blinded to the result of the test, but all received a standardized briefing on current scientific knowledge of diving physiology and “low-bubble” diving techniques; they were then allowed to dive without restrictions. After a mean interval of 8 years, a questionnaire was sent collecting data on their dives and cases of DCS (if any occurred). Results: Data was collected on 148 divers totaling 66,859 dives. There was no significant difference in diving data between divers with or without RLS. Divers with RLS had a 3.02 times higher incidence of (confirmed) DCS than divers without RLS (p = 0.04). When all cases of (confirmed or possible DCS) were considered, the Relative Risk was 1.42 (p = 0.46). DCS occurred mainly in divers who did not dive according to “low-bubble” diving techniques, in both groups. Conclusion: This prospective study confirms that DCS is more frequent in divers with RLS (such as a PFO), with a Relative Risk of 1.42 (all DCS) to 3.02 (confirmed DCS). It appears this risk is linked to diving behavior, more specifically diving to the limits of the adopted decompression procedures.

SUBMITTER: Germonpre P

PROVIDER: S-EPMC8586212 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Decompression sickness (DCS) is a potentially fatal condition usually observed after scuba diving. It involves bubble formation in blood and tissues from dissolved inert gas (usually nitrogen or helium), secondary to decreases in ambient pressure (decompression).To the best of our knowledge, no study has evaluated a DCS-induced transcriptomic signature in humans. In this study, we aim to explore the evolution of leukocyte gene expression in human subjects with DCS compared to closely matched divers after uneventful diving using a hypothesis-free RNA sequencing approach .Recruitment of DCS cases (n = 7) and controls (n = 6) was carried out using specific criteria. For both DCS cases and controls, whole blood was sampled at two time points, T1 - within 8 hours of surfacing from diving and T2 - at 40-44 hours after surfacing. Prior to sampling at T2, subjects were fasted for 10 hours. Specific exclusion criteria included a) age < 18 years b) self-reported consumption of alcohol and/or strenuous physical activity before T2 c) symptoms suggestive of delayed DCS presentation in controls at T2 d) acute life-threatening clinical complications or death within 72 hours of surfacing. All cases received emergency HBO as per United States Navy Treatment Table Six between T1 and T2.For RNA isolation, 2.5mL of whole blood was collected in a PAXgene® Blood RNA Tube (PreAnalytiX, Qiagen/BD) from DCS cases and controls at both T1 and T2. The quality of RNA was evaluated by RNA Integrity Number (RIN) determination using the RNA6000 Nano protocol on an Agilent 2100 Bioanalyzer system (Agilent, USA). The RIN values for samples undergoing transcriptome analysis ranged from 7.8 to 9.3. Depletion of alpha and beta globin mRNA was carried out using the GLOBINclear™ kit (ThermoFisher Scientific). To minimize batch effects, all samples were processed simultaneously by the same investigator. RNA samples were submitted for library generation and sequencing by the Beijing Genomics Institute (BGI-Shenzhen). Briefly, poly(A) mRNA was enriched using poly(T) oligo-attached magnetic beads, followed by fragmentation. First strand cDNA synthesis was carried out using random hexamer N6 primers and reverse transcriptase. Following adaptor ligation to cDNA fragments, PCR amplification and purification, single stranded DNA circles were generated in a final library. DNA nanoballs (DNBs) were subsequently generated by rolling circle replication, which underwent paired end sequencing (100bp) on the BGI DNBseq platform.

Project description:BackgroundArterialized vein flap is a kind of unphysiological flap. Unphysiological reconstruction of blood circulation leads to higher load than that supported by physiological flap and is the culprit of flap swelling, blood stasis, skin blistering, and necrosis after flap grafting. To resolve the multiple disadvantages of traditional flap grafting, by introducing the principles of fluid mechanics, shunt-decompression surgery is prepared to decline the circulation preload and improve the prognosis of arterialized vein flap grafting.MethodsBy introducing the principles of fluid mechanics, we established the model of shunt-decompression arterialized vein flap, which satisfied the common properties of general fluid that the interface pressure between object and fluid is reduced when the velocity of fluid is increased and vice versa-the effect of Bernoulli. Under this rule, we anastomose the arterialized vein to the branch of main artery of recipient region or make end-to-side anastomosis, which can maintain the blood flow of main artery, decrease the perfusion of flap, and preserve the decompressive effect of main artery to branches. From March, 2016 to September, 2016, we performed animal experiments on ten male bama mini pigs with average weight of 28?±?2.35 kg. Superior epigastric artery of pig was used for feeding artery to arterialize the superficial epigastric veins. The total area of flap is 8 cm?×?6 cm. End-to-side anastomosis and end-to-end anastomosis were established in experimental group and control group, respectively. Doppler speckle perfusion imaging apparatus was used to monitor the alterations of flap perfusion, blood flow of flap, tissue swelling and survival of flaps.ResultsThe average flap perfusion (PU) at 1 week after surgery is 83.62?±?3.14 in experimental group and 98.14?±?6.54 in control group, respectively (P?<?0.05), indicating the significant reduction of flap blood perfusion in experimental group as compared with control group. As to the survival of flaps, 7 flaps completely survived, 3 showed partial necrosis, and no one was found as complete necrosis in experimental group, while only 3 flaps survived, and 4 flaps and 3 flaps showed partial necrosis and complete necrosis in control group, respectively (P?<?0.05).ConclusionBased on the physiological features of arterialized vein flap and its problems in clinical application, we improved the anastomosis strategy of flap grafting and obtained excellent experimental outcomes, which provides an insight for the clinical application of arterialized vein flaps.

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Increased Risk of Decompression Sickness When Diving With a Right-to-Left Shunt: Results of a Prospective Single-Blinded Observational Study (The “Carotid Doppler” Study)

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