Altered Venous Blood Nitric Oxide Levels at Depth and Related Bubble Formation During Scuba Diving

Introduction: Nitric oxide (NO) plays an important role in the physiology and pathophysiology of diving, and the related endothelial dysfunction and oxidative stress roles have been extensively investigated. However, most available data have been obtained before and after the dive, whilst, as far as we know, no data is available about what happens during the water immersion phase of dive. The scope of this study is to investigate the Nitrate and Nitrite (NOX) concentration and the total plasma antioxidant capacity (TAC) before, during and after a single SCUBA dive in healthy scuba diving volunteers, as well as to look for evidence of a possible relationship with venous gas bubble formation.Materials and Methods: Plasma, obtained from blood of 15 expert SCUBA divers, 13 male and 2 female, was investigated for differences in NOX and TAC values in different dive times. Differences in NOX and TAC values in subjects previously known as “bubble resistant” (non-bubblers – NB) and “bubble prone” (Bubblers – B) were investigated.Results: We found a statistically significant increase of NOX plasma concentration in the “bottom blood draw” and in the “safety stop blood draw” as compared to the basal pre diving condition. We did not find any difference in NOX plasma concentration between the basal value and the post diving samples. We did not find any significant statistical difference in TAC in the bottom blood sample, while the safety-stop and the post-dive samples showed higher TAC values compared with the basal value. We did not find any difference in NOX and TAC mean values between non-bubblers and Bubblers.Discussion: Our protocol, by including underwater blood drawing, allowed to monitor plasma NOX changes occurred during diving activity, and not only by comparing pre and post diving values. It is particularly interesting to note that the increased NOX values found at the bottom and at the safety stop were not observed at post dive sampling (T0, T30, T60), showing a very rapid return to the pre-dive values. In this preliminary study we did not find any relationship between bubble formation and changes in NOX parameters and TAC response

Feasibility of chest ultrasound up to 42 m underwater

After recent advancements, ultrasound has extended its applications from bedside clinical practice to wilderness medicine. Performing ultrasound scans in extreme environments can allow direct visualization of unique pathophysiological adaptations but can be technically challenging. This paper summarizes how a portable ultrasound apparatus was marinized to let scientific divers and sonographers perform ultrasound scans of the lungs underwater up to - 42 m. A metallic case protected the ultrasound apparatus inside; a frontal transparent panel with a glove allowed visualization and operation of the ultrasound by the diving sonographer. The inner pressure was equalized with environmental pressure through a compressed air tank connected with circuits similar to those used in SCUBA diving. Finally, the ultrasound probe exited the metallic case through a sealed aperture. No technical issues were reported after the first testing step and the real experiments

Critical Flicker Fusion Frequency: A Marker of Cerebral Arousal During Modified Gravitational Conditions Related to Parabolic Flights

In situ evaluation of human brain performance and arousal remains challenging during operational circumstances, hence the need for a rapid, reliable and reproducible tool. Here we hypothesized that the Critical flicker fusion frequency (CFFF) reflecting/requiring visual integration, visuo-motor skills and decision-taking process might be a powerful, fast and simple tool in modified gravity environments. Therefore 11 male healthy volunteers were assessed for higher cognitive functions with CFFF during parabolic flights. They were assessed at different time points: upon arrival to the base, 30 min after subcutaneous scopolamine administration, before parabolas, during hypergravity and microgravity at break time (between the 16th and the 17th parabola), on the return flight and on the ground after landing. First, a stable, and consistent measurement of CFFF could be obtained within 12 s. Second, under modified gravitational conditions, the perceptual ability of participants is significantly modified. Compared to the baseline, evolution is characterized by a significant increase of CFFF when in microgravity (0g: 106.9 ± 5.5%), and a significant decrease of CFFF while in hypergravity (2g: 94.5 ± 3.8%). Other time-points were not statistically different from the baseline value. Although the underlying mechanism is still debated, we suggest that the CFFF test is a global marker of cerebral arousal as the result of visuo-motor and decision taking testing based on a simple visual stimulus with an uncomplicated set up that could be used under various environmental conditions. The authors express an opinion that it would be advisable to introduce CFFF measurement during spaceflights as it allows individual longitudinal assessment of individual ability even under conditions of incomplete physiological compensation, as shown here during parabolic flights

ADVANCED VIRTUALLY ASSISTED TELEMEDICINE in ADVERSE REMOTENESS (AVATAR)

The popularity of extreme sport and activities in remotes areas is steadily increasing together with the number of participant and correlated diseases per year. Until today all the emergencies in remote areas are, at best, managed by a telephone interview, without any real time physiological data evaluation by the attending physician. This kind of current service shows evident weaknesses: 1. It is based exclusively on a telephone contact 2. There are no automatic mechanisms to intercept and prevent critical situations 3. Is impossible to send automatic alarms in case of need 4. It assumes that the injured has active telephone network coverage 5. It assumes that the injured can actively interact with the emergency alarm center or that other bystanders can do so 6. All the health information is collected by telephone interview without any “real” physiological data obtained by the patient The object of AVATAR: (Advanced Virtually Assisted Telemedicine in Adverse Remoteness), focuses on developing and assembling technologies allowing to monitor, record, transmit, process physiological data, and, as a consequence, provide assistance and guidance by remote control to: bystanders, rescuers, health-care professionals, as well as possibly patients themselves, in case of emergencies in extreme environment such as: diving, high altitude and space. The project aims at providing real time physiological and environmental information from remote areas and to develop specific algorithms to elaborate this information to permit a more accurate management of accidents in remote areas, based on an advanced bidirectional telemedicine concept. The final goal, and also the original challenge of AVATAR, could be to realize a dedicated international control center able to receive and manage physiological and environmental data received from remote areas and, supported by customized wearable technology, augmented and virtual reality and exposure monitoring electronic devices, to provide appropriate instructions to assist accident victims supported by real-time medical, environmental and exposure information. During the three years of Ph.D we developing and assembling devices allowing to monitor, recording and transmit physiological and environmental data and developing the data base, the algorithms and the software allowing the AVATAR system function. To permit a correct interpretation of remotely collected data we also developing physiological scientific protocols to investigate the body adaptation to extreme environment.The popularity of extreme sport and activities in remotes areas is steadily increasing together with the number of participant and correlated diseases per year. Until today all the emergencies in remote areas are, at best, managed by a telephone interview, without any real time physiological data evaluation by the attending physician. This kind of current service shows evident weaknesses: 1. It is based exclusively on a telephone contact 2. There are no automatic mechanisms to intercept and prevent critical situations 3. Is impossible to send automatic alarms in case of need 4. It assumes that the injured has active telephone network coverage 5. It assumes that the injured can actively interact with the emergency alarm center or that other bystanders can do so 6. All the health information is collected by telephone interview without any “real” physiological data obtained by the patient The object of AVATAR: (Advanced Virtually Assisted Telemedicine in Adverse Remoteness), focuses on developing and assembling technologies allowing to monitor, record, transmit, process physiological data, and, as a consequence, provide assistance and guidance by remote control to: bystanders, rescuers, health-care professionals, as well as possibly patients themselves, in case of emergencies in extreme environment such as: diving, high altitude and space. The project aims at providing real time physiological and environmental information from remote areas and to develop specific algorithms to elaborate this information to permit a more accurate management of accidents in remote areas, based on an advanced bidirectional telemedicine concept. The final goal, and also the original challenge of AVATAR, could be to realize a dedicated international control center able to receive and manage physiological and environmental data received from remote areas and, supported by customized wearable technology, augmented and virtual reality and exposure monitoring electronic devices, to provide appropriate instructions to assist accident victims supported by real-time medical, environmental and exposure information. During the three years of Ph.D we developing and assembling devices allowing to monitor, recording and transmit physiological and environmental data and developing the data base, the algorithms and the software allowing the AVATAR system function. To permit a correct interpretation of remotely collected data we also developing physiological scientific protocols to investigate the body adaptation to extreme environment

Flying after diving: should recommendations be reviewed? In-flight echocardiographic study in bubble-prone and bubble-resistant divers.

Inert gas accumulated after multiple recreational dives can generate tissue supersaturation and bubble formation when ambient pressure decreases. We hypothesized that this could happen even if divers respected the currently recommended 24-hour pre-flight surface interval (PFSI).info:eu-repo/semantics/publishe

Continuous real-time monitoring and recording of glycemia during scuba diving: pilot study

Introduction: Insulin-dependent diabetes has been considered a scuba diving contraindication. This is currently being reconsidered for well-controlled dia- betes. We developed a real-time continuous glucose monitor (CGM) to check glycemia, or blood glucose (BG), during diving, both for prospective studies and to increase diabetic diver safety, allowing for real-time control of glycemia and hypoglycemia pre- vention. To ensure CGM measurement accuracy we tested the method under hyperbaric conditions. Materials and methods: Two experienced diabetic divers were studied during a one-week diving cruise. BG was monitored every five minutes on every dive, by a dedicated CGM, and values were visible to the divers throughout their dives. The mean of relative difference (MRD) between CGM and capillary blood glucose was calculated. Measurement accuracy was assessed according to ISO guideline 15197 and by Clarke Error Grid (CEG) analysis. Results: Both divers showed gradual BG decrease during diving. Hyperbaric chamber accuracy tests showed two of 26 MRD values (7.7%) slightly exceed- ing the ISO-15197 allowed difference (5%). However, our data suggest that this discrepancy may have been an artefact. Discussion: Our data (even limited to two subjects only) agree with the current literature showing that also in our investigated subjects diving does not imply significant risks of hypoglycemia. The use of a real-time CGM by diabetic divers during their dives can provide immediate information on BG values and trends, thus significantly improving diving safety. The accuracy tests comparing continuous glucose monitoring (CGM) and capillary blood glucose mea- surement (CBM) data recorded under hyperbaric conditions showed that data recorded under pressure are very close to the ISO-15197 and CEG acceptable limits

Cellular Glucose Uptake During Breath-Hold Diving in Experienced Male Breath-Hold Divers

Abstract Background The physiological and pathophysiological mechanisms that govern diving, both self-contained underwater breathing apparatus (SCUBA) and breath-hold diving (BH-diving), are in large part well known, even if there are still many unknown aspects, in particular about cell metabolism during BH-diving. The scope of this study was to investigate changes in glycemia, insulinemia, and the catecholamine response to BH-diving, to better understand if the insulin-stimulated glucose uptake mechanism is involved in cellular metabolism in this sport. Methods Twenty male experienced healthy breath-hold divers were studied. Anthropometric information was obtained. Glycemia, insulinemia, and catecholamine response were investigated before and after the series of BH-diving. Results We found a statistically significant decrease in the blood glucose levels between before and after dives (mean 94.3 ± 11.6 vs. 83.5 ± 12.5 mg/dl) P = 0.001 and a statistically significant increase in blood insulin value (median 4.5 range 3.4/6.4 vs. 7.0 range 4.2/10.2 mcgU/ml) P < 0.0001. Also, we found a statistically significant increase of catecholamine production (median 14.0 range 8/18 vs. 15.5 range 10.0/21.0 μg) P < 0.0001. Conclusions The increase in blood insulin during BH-diving associated with the decrease of blood glucose levels could indicate that the upregulating cellular uptake is not caused by activation of the specific glucose transporters. Particular diving-related conditions such as the diving reflex, the intermittent hypoxia/hyperoxia, and the particular environmental condition could play an important role in the mechanism involved in glycemia decrease in BH-diving. Our data confirm that the adaptations to BH-diving are caused by complex mechanisms and involve many peculiar responses still in large part unknown

Flying after diving: in-flight echocardiography after a scuba diving week.

Cialoni D, Pieri M, Balestra C, Marroni A. Flying after diving: in-flight echocardiography after a scuba diving week. Aviat Space Environ Med 2014; 85:993-8.Journal Articleinfo:eu-repo/semantics/publishe

Oxidative stress and motion sickness in one crew during competitive offshore sailing

Competitive Offshore Ocean Sailing is a highly demanding activity in which subjects are exposed to psychophysical stressors for a long time. To better define the physiological adaptations, we investigated the stress response of subjects exposed to 3-days long ocean navigation with disruption of circadian rhythms. 6 male subjects were involved in the study and provided urine and saliva samples before setting sail, during a single day of inshore sailing, during 3-days long ocean navigation, and at the arrival, to measure oxidative stress, cortisol, nitric oxide metabolites (NOx) and metabolic response. Motion Sickness questionnaires were also administered during the navigation. The crew suffered a mean weight loss of 1.58 kg. After the long navigation, a significant increase in ROS production and decrease in total antioxidant capacity and uric acid levels were observed. Lipid peroxidation, NO metabolites, ketones, creatinine, and neopterin levels were also increased. Furthermore, a significant increase in cortisol levels was measured. Finally, we found a correlation between motion sickness questionnaires with the increase of NOx, and no correlation with cortisol levels. Physical and psychological stress response derived from offshore sailing resulted in increased oxidative stress, nitric oxide metabolites, and cortisol levels, unbalanced redox status, transient renal function impairment, and ketosis. A direct correlation between motion sickness symptoms evaluated through questionnaires and NOx levels was also found