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Divers breathe higher partial pressures of oxygen at depth than at the surface. The literature and diving community are divided on whether or not oxygen is narcotic. Conversely, hyperbaric oxygen may induce dose-dependent cerebral hyperexcitability. This study evaluated whether hyperbaric oxygen causes similar narcotic effects to nitrogen, and investigated oxygen's hyperexcitability effect. Twelve human participants breathed "normobaric" air and 100% oxygen, and "hyperbaric" 100% oxygen at 142 and 284 kPa, while psychometric performance, electroencephalography (EEG), and task load perception were measured. EEG was analyzed with functional connectivity and temporal complexity algorithms. The spatial functional connectivity, estimated using mutual information, was summarized with the global efficiency network measure. Temporal complexity was calculated with a "default-mode-network (DMN) complexity" algorithm. Hyperbaric oxygen-breathing caused no change in EEG global efficiency or in the psychometric test. However, oxygen caused a significant reduction of DMN complexity and a reduction in task load perception. Hyperbaric oxygen did not cause the same changes in EEG global efficiency seen with hyperbaric air, which likely related to a narcotic effect of nitrogen. Hyperbaric oxygen seemed to disturb the time evolution of EEG patterns that could be taken as evidence of early oxygen-induced cortical hyperexcitability. These findings suggest that hyperbaric oxygen is not narcotic and will help inform divers' decisions on suitable gas mixtures.

Arterial blood gas (ABG) measurements at both maximum depth and at resurfacing prior to breathing have not previously been measured during free dives conducted to extreme depth in cold open-water conditions. An elite free diver was instrumented with a left radial arterial cannula connected to two sampling syringes through a low-volume splitting device. He performed two open-water dives to a depth of 60 m (197′, 7 atmospheres absolute pressure) in the constant weight with fins competition format. ABG samples were drawn at 60 m (by a mixed-gas scuba diver) and again on resurfacing before breathing. An immersed surface static apnea, of identical length to the dives and with ABG sampling at identical times, was also performed. Both dives lasted approximately 2 min. Arterial partial pressure of oxygen ([Formula: see text]) increased during descent from an indicative baseline of 15.8 kPa (after hyperventilation and glossopharyngeal insufflation) to 42.8 and 33.3 kPa (dives 1 and 2) and decreased precipitously (to 8.2 and 8.6 kPa) during ascent. Arterial partial pressure of carbon dioxide ([Formula: see text]) also increased from a low indicative baseline of 2.8 kPa to 6.3 and 5.1 kPa on dives 1 and 2; an increase not explained by metabolic production of CO(2) alone since [Formula: see text] actually decreased during ascent (to 5.2 and 4.5 kPa). Surface static apnea caused a steady decrease in [Formula: see text] and increase in [Formula: see text] without the inflections provoked by depth changes. Lung compression and expansion provoke significant changes in both [Formula: see text] and [Formula: see text] during rapid descent and ascent on a deep free dive. These changes generally support predictive hypotheses and previous findings in less extreme settings. NEW & NOTEWORTHY Arterial blood gas measurements at both maximum depth and the surface before breathing on the same dive have not previously been obtained during deep breath-hold dives in cold open-water conditions and competition dive format. Such measurements were obtained in two dives to 60 m (197′) of 2 min duration. Changes in arterial oxygen and carbon dioxide (an increase during descent, and a decrease during ascent) support previous observations in less extreme dives and environments.

PURPOSE: In this study, we investigated factors associated with program adherence and patient satisfaction with a home-based physical activity program (Onco-Move, N = 77) and a supervised exercise program with a home-based component (OnTrack, N = 76).METHODS: We assessed adherence via self-report (home-based program) and attendance records (supervised program). We used logistic regression analysis to identify sociodemographic, clinical and behavioural variables associated with program adherence. Patient satisfaction was assessed with self-report and is reported descriptively.RESULTS: Fifty-one percent of Onco-Move and 62% of OnTrack participants were adherent to the home-based program, while 59% of OnTrack participants were adherent to the supervised sessions. Higher baseline physical fitness was associated with higher adherence to home-based components. Higher disease stage and having a partner were associated with adherence to OnTrack supervised sessions. Overall satisfaction with the exercise programs was high, but ratings of coaching provided by professionals for the home-based components were low. Patients offered suggestions for improving delivery of the programs.CONCLUSIONS: These findings point to factors relevant to program adherence and suggest ways in which such programs can be improved. Providing additional time and training for health care professionals could improve the quality and hopefully the effectiveness of the interventions. The use of online diaries and smartphone apps may provide additional encouragement to participants. Finally, allowing greater flexibility in the planning and availability of supervised exercise training in order to accommodate the variability in cancer treatment schedules and the (acute) side effects of the treatments could also enhance program adherence.TRIAL REGISTRATION: Netherlands Trial Register, NTR2159. http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2159.

Connected consciousness, assessed by response to command, occurs in at least 5% of general anaesthetic procedures and perhaps more often in young people. Our primary objective was to establish the incidence of connected consciousness after tracheal intubation in young people aged 18-40 yr. The secondary objectives were to assess the nature of these responses, identify relevant risk factors, and determine their relationship to postoperative outcomes.This was an international, multicentre prospective cohort study using the isolated forearm technique to assess connected consciousness shortly after tracheal intubation.Of 344 enrolled subjects, 338 completed the study (mean age, 30 [standard deviation, 6.3] yr; 232 [69%] female). Responses after intubation occurred in 37/338 subjects (11%). Females (13%, 31/232) responded more often than males (6%, 6/106). In logistic regression, the risk of responsiveness was increased with female sex (odds ratio [ORConnected consciousness occured after intubation in 11% of young adults, with females at increased risk. Continuous exposure to anaesthesia between induction of anaesthesia and tracheal intubation should be considered to reduce the incidence of connected consciousness. Further research is required to understand sex-related differences in the risk of connected consciousness.

Divers commonly breathe air, containing nitrogen. Nitrogen under hyperbaric conditions is a narcotic gas. In dives beyond a notional threshold of 30 m depth (405 kPa) this can cause cognitive impairment, culminating in accidents due to poor decision making. Helium is known to have no narcotic effect. This study explored potential approaches to developing an electroencephalogram (EEG) functional connectivity metric to measure narcosis produced by nitrogen at hyperbaric pressures. Twelve human participants (five female) breathed air and heliox (in random order) at 284 and 608 kPa while recording 32-channel EEG and psychometric function. The degree of spatial functional connectivity, estimated using mutual information, was summarized with global efficiency. Air-breathing at 608 kPa (experienced as mild narcosis) caused a 35% increase in global efficiency compared to surface air-breathing (mean increase = 0.17, 95% CI [0.09-0.25], p = 0.001). Air-breathing at 284 kPa trended in a similar direction. Functional connectivity was modestly associated with psychometric impairment (mixed-effects model r

Background Nitrous oxide produces non–γ-aminobutyric acid sedation and psychometric impairment and can be used as scientific model for understanding mechanisms of progressive cognitive disturbances. Temporal complexity of the electroencephalogram may be a sensitive indicator of these effects. This study measured psychometric performance and the temporal complexity of the electroencephalogram in participants breathing low-dose nitrous oxide. Methods In random order, 20, 30, and 40% end-tidal nitrous oxide was administered to 12 participants while recording 32-channel electroencephalogram and psychometric function. A novel metric quantifying the spatial distribution of temporal electroencephalogram complexity, comprised of (1) absolute cross-correlation calculated between consecutive 0.25-s time samples; 2) binarizing these cross-correlation matrices using the median of all channels as threshold; (3) using quantitative recurrence analysis, the complexity in temporal changes calculated by the Shannon entropy of the probability distribution of the diagonal line lengths; and (4) overall spatial extent and intensity of brain complexity, was quantified by calculating median temporal complexity of channels whose complexities were above 1 at baseline. This region approximately overlay the brain’s default mode network, so this summary statistic was termed “default-mode-network complexity.” Results Nitrous oxide concentration correlated with psychometric impairment (r = 0.50, P < 0.001). Baseline regional electroencephalogram complexity at midline was greater than in lateral temporal channels (1.33 ± 0.14 bits vs. 0.81 ± 0.12 bits, P < 0.001). A dose of 40% N2O decreased midline (mean difference [95% CI], 0.20 bits [0.09 to 0.31], P = 0.002) and prefrontal electroencephalogram complexity (mean difference [95% CI], 0.17 bits [0.08 to 0.27], P = 0.002). The lateral temporal region did not change significantly (mean difference [95% CI], 0.14 bits [−0.03 to 0.30], P = 0.100). Default-mode-network complexity correlated with N2O concentration (r = −0.55, P < 0.001). A default-mode-network complexity mixed-effects model correlated with psychometric impairment (r2 = 0.67; receiver operating characteristic area [95% CI], 0.72 [0.59 to 0.85], P < 0.001). Conclusions Temporal complexity decreased most markedly in medial cortical regions during low-dose nitrous oxide exposures, and this change tracked psychometric impairment. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

Critical flicker fusion frequency (CFFF) has been used in various studies to measure the cognitive effects of gas mixtures at depth, sometimes with conflicting or apparently paradoxical results. This study aimed to evaluate a novel automatic CFFF method and investigate whether CFFF can be used to monitor gas-induced narcosis in divers., info:eu-repo/semantics/published

Introduction In 2018 12 children and one adult were anaesthetised before being extricated through over a kilometre of flooded cave in Thailand. Full face dive masks (FFMs) putatively capable of maintaining constant positive airway pressure (CPAP) were employed. Here we describe the anaesthetic intervention and investigate the CPAP capability of the FFM. Methods Pressure was measured inside and outside the Interspiro Divator FFM during 10 tidal and 10 vital capacity breaths in divers at the surface and submerged with the mask deployed on open-circuit scuba (10 divers); and a closed-circuit rebreather (five divers). Relative in-mask pressure was calculated as the difference between inside and outside pressures. We also measured the in-mask pressure generated by activation of the second stage regulator purge valve in open-circuit mode. Results When submerged in open-circuit mode the mean relative in-mask pressure remained positive in normal tidal breathing (inhalation 0.6 kPa [95% CI 0.3-0.9]; exhalation 1.1 [0.8-1.4]) and vital capacity breathing (inhalation 0.8 [0.4-1.1]; exhalation 1.2 [0.9-1.4]). As expected, the relative in-mask pressure was predominantly negative when used on closed-circuit with back mounted counter-lungs due to a negative static lung load. Mean in-mask pressure during purge valve operation was 3.99 kPa (approximately equal to 40 cmH2O) (range: 2.56 to 5.3 kPa). Conclusions The CPAP function of the Interspiro Divator FFM works well configured with open-circuit scuba. This may have contributed to the success of the Thailand cave rescue. Caution is required in generalising this success to other diving scenarios.

Introduction: A home-based, low-intensity physical activity program (Onco-Move) and a supervised, moderate-to-high intensity, combined resistance and aerobic exercise program (OnTrack) have proven to be effective in maintaining physical fitness and reducing fatigue among breast cancer patients undergoing adjuvant chemotherapy. This study evaluated the cost–utility and cost-effectiveness of Onco-Move and OnTrack. Methods: A total of 230 patients were randomized to Onco-Move, OnTrack, or usual care (UC). Health outcomes included quality-adjusted life years (QALYs), general and physical fatigue, and physical fitness measured at baseline, end of chemotherapy, and 6-month follow-up. Societal costs included professional and informal health care, work absenteeism, and unpaid productivity costs. Cost data were based on 3-monthly questionnaires, supplemented by medication data obtained from pharmacies. Results: Onco-Move is not likely to be cost-effective due to the relatively high willingness-to-pay necessary to reach reasonable probabilities of cost-effectiveness (QALY, general and physical fatigue). Incremental cost-effectiveness ratios for OnTrack compared to UC were €26,916/QALY, €788/1-point decrease in general fatigue and €1402/1-point decrease in physical fatigue. The probability of OnTrack being cost-effective ranged from 31% at a willingness-to-pay (WTP) of €0–79% at a WTP of €80,000/QALY, 97% at a WTP of €15,000/1-point decrease in general fatigue, and 86% at a WTP of €24,000/1-point decrease in physical fatigue. Both interventions had a low probability of being cost-effective for physical fitness. The probability of cost-effectiveness for both interventions was greater among compliant participants. Conclusions: Onco-Move is not likely to be cost-effective. Depending on the decision-makers’ willingness-to-pay, OnTrack could be considered cost-effective in comparison with UC. Trial registration Clinical trial registration number of the Netherlands Trial Register—NTR2159.

Introduction Gas narcosis impairs divers when diving deeper. Pupillometry is sensitive to alcohol intoxication and it has been used in anaesthesia to assess nitrous oxide narcosis. It is a potential novel method to quantify narcosis in diving. The aim of this study was to evaluate pupillometry for objective measurement of narcosis during exposure to hyperbaric air or nitrous oxide. Method Pupil size in 16 subjects was recorded directly at surface pressure and during air breathing at 608 kPa (equivalent to 50 metres' seawater depth) in a hyperbaric chamber. Another 12 subjects were exposed to nitrous oxide at end-tidal percentages of 20, 30 and 40% in random order at surface pressure. Pupil size and pupil light reflex were recorded at baseline and at each level of nitrous oxide exposure. Results Pupil size did not significantly change during exposure to hyperbaric air or nitrous oxide. The pupil light reflex, evaluated using percentage constriction and minimum diameter after exposure to a light stimulus, was affected significantly only during the highest nitrous oxide exposure - an end-tidal level of 40%. Conclusion Pupillometry is insensitive to the narcotic effect of air at 608 kPa in the dry hyperbaric environment and to the effects of low dose nitrous oxide. Pupillometry is not suitable as a monitoring method for gas narcosis in diving.

Purpose: We report the recruitment rate, reasons for and factors influencing non-participation, and descriptive results of a randomized controlled trial of two different exercise programs for patients with colon cancer undergoing adjuvant chemotherapy. Methods: Participants were randomized to a low-intensity, home-based program (Onco-Move), a moderate- to high-intensity, combined supervised resistance and aerobic exercise program (OnTrack), or Usual Care. Non-participants provided reasons for non-participation and were asked to complete a questionnaire assessing behavioral and attitudinal variables. Trial participants completed performance-based and self-reported outcome measures prior to randomization, at the end of chemotherapy, and at the 6-month follow-up. Results: Twenty-three of 63 referred patients agreed to participate in the trial. All 40 non-participants provided reasons for non-participation. Forty-five percent of the non-participants completed the questionnaire. Those who did not want to exercise had higher fatigue scores at baseline and a more negative attitude toward exercise. Compliance to both programs was high and no adverse events occurred. On average, the colon cancer participants were able to maintain or improve their physical fitness levels and maintain or decrease their fatigue levels during chemotherapy and follow-up. Conclusions: Recruitment of patients with colon cancer to a physical exercise trial during adjuvant chemotherapy proved to be difficult, underscoring the need to develop more effective strategies to increase participation rates. Both home-based and supervised programs are safe and feasible in patients with colon cancer undergoing chemotherapy. Effectiveness needs to be established in a larger trial. Trial registration: Netherlands Trial Register - NTR2159

Objective Only between 25% and 50% of patients invited to participate in clinical trial-based physical exercise programs during cancer treatment agree to do so. The purpose of this study was to identify factors associated significantly with the decision (not) to participate in a randomized controlled trial of physical exercise during adjuvant chemotherapy for breast cancer. Methods Based on questionnaire data, we compared trial participants and non-participants on a range of sociodemographic, clinical health-related, practical, behavioral, and attitudinal variables. Results Two hundred thirty of 524 patients agreed to participate in the trial (44%). The 294 (56%) non-participants indicated that they wanted to exercise on their own or that they did not wish to exercise in the context of a trial. Those who preferred to exercise on their own were relatively similar to trial participants but were more likely to be in the maintenance exercise stage. Those non-participants who did not wish to exercise had a significantly lower level of education, were less likely to be working, reported more fatigue and lower health-related quality of life, had lower sense of self-efficacy, more negative attitudes towards exercise, less social support, and perceived fewer benefits and more barriers to exercising during treatment than trial participants. Conclusion Minimizing practical barriers to participation, providing educational materials on the potential benefits of exercise, and giving adequate professional and social network encouragement may increase the number of patients willing to exercise during treatment and to participate in such studies.

Purpose We evaluated the effectiveness of a low-intensity, home-based physical activity program (Onco-Move) and a moderate- to high-intensity, combined supervised resistance and aerobic exercise program (OnTrack) versus usual care (UC) in maintaining or enhancing physical fitness, minimizing fatigue, enhancing health-related quality of life, and optimizing chemotherapy completion rates in patients undergoing adjuvant chemotherapy for breast cancer. Patients and Methods We randomly assigned patients who were scheduled to undergo adjuvant chemotherapy (N = 230) to Onco-Move, OnTrack, or UC. Performance-based and self-reported outcomes were assessed before random assignment, at the end of chemotherapy, and at the 6-month follow-up. We used generalized estimating equations to compare the groups over time. Results Onco-Move and OnTrack resulted in less decline in cardiorespiratory fitness (P < .001), better physical functioning (P ≤ .001), less nausea and vomiting (P = .029 and .031, respectively) and less pain (P = .003 and .011, respectively) compared with UC. OnTrack also resulted in better outcomes for muscle strength (P = .002) and physical fatigue (P < .001). At the 6-month follow-up, most outcomes returned to baseline levels for all three groups. A smaller percentage of participants in OnTrack required chemotherapy dose adjustments than those in the UC or Onco-Move groups (P = .002). Both intervention groups returned earlier (P = .012), as well as for more hours per week (P = .014), to work than the control group. Conclusion A supervised, moderate- to high-intensity, combined resistance and aerobic exercise program is most effective for patients with breast cancer undergoing adjuvant chemotherapy. A home-based, low-intensity physical activity program represents a viable alternative for women who are unable or unwilling to follow the higher intensity program.

Only between 25% and 50% of patients invited to participate in clinical trial-based physical exercise programs during cancer treatment agree to do so. The purpose of this study was to identify factors associated significantly with the decision (not) to participate in a randomized controlled trial of physical exercise during adjuvant chemotherapy for breast cancer.Based on questionnaire data, we compared trial participants and non-participants on a range of sociodemographic, clinical health-related, practical, behavioral, and attitudinal variables.Two hundred thirty of 524 patients agreed to participate in the trial (44%). The 294 (56%) non-participants indicated that they wanted to exercise on their own or that they did not wish to exercise in the context of a trial. Those who preferred to exercise on their own were relatively similar to trial participants but were more likely to be in the maintenance exercise stage. Those non-participants who did not wish to exercise had a significantly lower level of education, were less likely to be working, reported more fatigue and lower health-related quality of life, had lower sense of self-efficacy, more negative attitudes towards exercise, less social support, and perceived fewer benefits and more barriers to exercising during treatment than trial participants.Minimizing practical barriers to participation, providing educational materials on the potential benefits of exercise, and giving adequate professional and social network encouragement may increase the number of patients willing to exercise during treatment and to participate in such studies. Copyright © 2015 John WileySons, Ltd.

Background Cancer chemotherapy is frequently associated with a decline in general physical condition, exercise tolerance, and muscle strength and with an increase in fatigue. While accumulating evidence suggests that physical activity and exercise interventions during chemotherapy treatment may contribute to maintaining cardiorespiratory fitness and strength, the results of studies conducted to date have not been consistent. Additional research is needed to determine the optimal intensity of exercise training programs in general and in particular the relative effectiveness of supervised, outpatient (hospital- or physical therapy practice-based) versus home-based programs. Methods This multicenter, prospective, randomized trial will evaluate the effectiveness of a low to moderate intensity, home-based, self-management physical activity program, and a high intensity, structured, supervised exercise program, in maintaining or enhancing physical fitness (cardiorespiratory fitness and muscle strength), in minimizing fatigue and in enhancing the health-related quality of life (HRQoL). Patients receiving adjuvant chemotherapy for breast or colon cancer (n = 360) are being recruited from twelve hospitals in the Netherlands, and randomly allocated to one of the two treatment groups or to a 'usual care' control group. Performance-based and self-reported outcomes are assessed at baseline, at the end of chemotherapy and at six month follow-up. Discussion This large, multicenter, randomized clinical trial will provide additional empirical evidence regarding the effectiveness of physical exercise during adjuvant chemotherapy in enhancing physical fitness, minimizing fatigue, and maintaining or enhancing patients' quality of life. If demonstrated to be effective, exercise intervention programs will be a welcome addition to the standard program of care offered to patients with cancer receiving chemotherapy. Trial registration This study is registered at the Netherlands Trial Register (NTR 2159)