Narcotic Nitrogen Effects Persist after a Simulated Deep Dive.

Background and Objectives: Scuba divers often experience persistent inert gas narcosis (IGN) even after surfacing. This study aimed to test the hypothesis that breathing oxygen (O2) before surfacing can reduce postdive IGN. Materials and Methods: A group of 58 experienced divers underwent a 5 min dive at a depth of 50 m in a multi-place hyperbaric chamber. They were decompressed using air (air group). Another group of 28 divers (O2 group) breathed 100% O2 during the end of decompression. Prior to and after the dive, all participants performed the Sharpened Romberg test (SRT) and a modified tweezers test. Results: In the air group, the number of positive SRT results increased postdive (47% vs. 67%), indicating a greater impairment in the vestibular system (Cohen's d = 0.41). In the O2 group, the percentage of positive SRT results remained constant at 68% both before and after the dive. In terms of the modified tweezers test, the air group showed no significant change in the number of picked beads (40 ± 9 vs. 39 ± 7), while the O2 group demonstrated an increase (36 ± 7 vs. 44 ± 10) (Cohen's d = 0.34). Conclusion: The results reveal that the SRT revealed a negative effect of nitrogen (N2) on the vestibular system in the air group. The increased number of beads picked in the O2 group can be attributed to the learning effect, which was hindered in the air group. Consistent with our hypothesis, breathing O2 during decompression appears to reduce postdive IGN.

Reply to Mankowska et al. Comment on "Muth et al. Assessing Critical Flicker Fusion Frequency: Which Confounders? A Narrative Review. Medicina 2023, 59, 800".

First and foremost, we like to express our gratitude for the praise bestowed upon our narrative review [...].

Sleep Duration on Workdays Is Correlated with Subjective Workload and Subjective Impact of High Workload on Sleep in Young Healthy Adults.

Psychosocial stress is widespread worldwide and particularly affects young adults. There is a close and bidirectional relationship between sleep quality and mental health. Sleep duration, which is an important feature of sleep quality, shows both intra-individual variations and inter-individual differences. Internal clocks control individual sleep timing, which, in turn, defines the chronotype. On workdays, however, the end and duration of sleep are largely limited by external factors, such as alarm clocks, especially in later chronotypes. The aim of this study is to investigate whether there is a relationship between sleep timing and duration on workdays and measures for psychosocial stress, such as anxiety and depression; subjective workload; and the subjective impact of a high workload on sleep. We used a combination of Fitbit wearable actigraphy data and a questionnaire survey of young, healthy medical students and calculated correlations between the respective variables. We found that a shorter sleep duration on workdays is associated with a higher subjective workload and a higher subjective impact of a high workload on sleep, which, in turn, are associated with higher measures of anxiety and depression. Our study contributes to understanding the importance of sleep timing/duration and their regularity on weekdays for subjectively perceived psychosocial stress.

Assessing Critical Flicker Fusion Frequency: Which Confounders? A Narrative Review.

The critical flicker fusion frequency (cFFF) refers to the frequency at which a regularly recurring change of light stimuli is perceived as steady. The cFFF threshold is often assessed in clinics to evaluate the temporal characteristics of the visual system, making it a common test for eye diseases. Additionally, it serves as a helpful diagnostic tool for various neurological and internal diseases. In the field of diving/hyperbaric medicine, cFFF has been utilized to determine alertness and cognitive functions. Changes in the cFFF threshold have been linked to the influence of increased respiratory gas partial pressures, although there exist inconsistent results regarding this effect. Moreover, the use of flicker devices has produced mixed outcomes in previous studies. This narrative review aims to explore confounding factors that may affect the accuracy of cFFF threshold measurements, particularly in open-field studies. We identify five broad categories of such factors, including (1) participant characteristics, (2) optical factors, (3) smoking/drug use, (4) environmental aspects, and (5) breathing gases and partial pressures. We also discuss the application of cFFF measurements in the field of diving and hyperbaric medicine. In addition, we provide recommendations for interpreting changes in the cFFF threshold and how they are reported in research studies.

[Potential improvements of psychosocial working conditions in general practices: Development of a discussion guide for medical assistants for staff appraisals]. / Mögliche Verbesserungen der psychosozialen Arbeitsbedingungen in Hausarztpraxen: Entwicklung eines Gesprächsleitfadens für Medizinische Fachangestellte zur Nutzung für Mitarbeitergespräche.

BACKGROUND: Staff appraisals can provide employees and their supervisors with the opportunity to improve their communication and collaboration. However, one can assume that staff appraisals are not yet common instruments for human resources management in physician practices. The aim of this study was to develop a discussion guide for medical assistants (MAs) in general practices to support MAs in preparing, carrying out and documenting staff appraisals. METHODS: MAs were recruited through their professional organization [Verband medizinischer Fachberufe e. V.] and social media (06/2020-10/2020). An early draft of the discussion guide was devised comprising an introduction, a checklist for logistic preparation, a documentation sheet and a section to prepare the content of the meeting. The discussion guide was revised based on interviews with MAs who also rated the instrument. Data collection, analyses and the revision of the guide were carried out in an iterative process to the point where no further significant suggestions for improvement were made. RESULTS: In total, 20 interviews were conducted. Revisions were based on recommendations pertaining to a) how to interact with the supervisor (e. g., raising awareness of and responding to changes of the topic; anticipating counterarguments, scheduling of follow-up meetings), b) the choice of topics, c) additional measures to respond to MAs' needs (e. g., rotation to distribute tasks), and d) the preparation of the staff appraisal (e. g., rehearsals with an experienced colleague). Both the likelihood to use the guide in the future and its usefulness for staff appraisals were considered to be high. DISCUSSION AND CONCLUSION: We developed a discussion guide for and with MAs in general practices which can be helpful in preparing, conducting and documenting staff appraisals. This serves the purpose of bringing one's psychosocial working conditions to the supervisor's attention and to possibly improve them. To further improve the tool, future research should explore the experiences of MAs and physicians who actually use the discussion guide.

Hyperoxia and the cardiovascular system: experiences with hyperbaric oxygen therapy.

Hyperoxia has been described to induce bradycardia by direct stimulation of the parasympathetic nervous system. Also, hyperoxia has been found to increase blood pressure by an elevation of vascular resistance. However, the latter effect itself would induce bradycardia by baroreceptor stimulation. This single-arm monocentric retrospective study aims to evaluate the correlation between these effects by investigating the relation between oxygen (O2) administration and heart rate over time. Data were collected from 23 patients without cardiovascular problems undergoing hyperbaric oxygen therapy (2.4 bar) retrospectively. During single oxygen bouts, transcutaneously measured partial pressure of O2 was increased. During this surge of oxygen pressure, the arterial blood pressure was increased while the heart rate was decreased. Respiration rate was maintained independently from breathing 100% O2 or air. During single oxygen bouts, the half-life of transcutaneously measured partial pressure of O2 was 5.4 ± 2.1 mmHg/s, and the half-life of heart rate was 0.45 ± 0.19 beats/min. It has been shown that hyperbaric oxygen therapy increases the transcutaneously measured partial pressure of O2. This increase was rather fast, followed by a rather slow decrease in HR. This finding does not support direct vagal activation. Heart rate is not decreased due to a direct vagal activation during hyperbaric oxygen therapy. Our single-arm, retrospective study has additionally confirmed that oxidative stress injures the endothelium, and the reduced endothelial-derived vasodilators cause vasoconstriction. As a consequence, blood pressure increases, and heart rate is then further decreased via the baroreceptor reflex.

Firefighters during training as divers: physiologic and psychomental stresses.

Objectives. Fire departments train divers for search, rescue and recovery in and under water. Their tasks likely exert major physical and psychological stress. This study hypothesizes that training is well balanced, following a learning spiral. Methods. Seven firefighters participated, performing 272 dives in different waters. Measurements included pulmonary function (body plethysmography); heart rate (HR) and air consumption during dives; personality variables with the state-trait anxiety inventory (STAI) and psychological stress with the task load index (NASA-TLX). Results. Pulmonary function was maintained at the end of training dives. During the dives, mean HR was 108 ± 23 bpm and mean air consumption 37 ± 15 L/min. Both values remained unchanged during training. The three highest STAI stanines (severe trait anxiety) were not considered, but median stanines and very low values were over-represented. Demands within the seven NASA-TLX areas were perceived differently. Sum of the scales 'very low', 'low' and 'mean' was ≥60%. In turn, the scale 'very high' was in none of the demands >10%. Conclusion. Physiological values remained unaltered throughout training, i.e. workload and increase in competence properly matched. The moderate manifestation of psychomental stress speaks for a group of highly selected individuals. Both candidate selection and design of the learning spiral was successful.

Oxygen-enriched Air Decreases Ventilation during High-intensity Fin-swimming Underwater.

Oxygen-enriched air is commonly used in the sport of SCUBA-diving and might affect ventilation and heart rate, but little work exists for applied diving settings. We hypothesized that ventilation is decreased especially during strenuous underwater fin-swimming when using oxygen-enriched air as breathing gas. Ten physically-fit divers (age: 25±4; 5 females; 67±113 open-water dives) performed incremental underwater fin-swimming until exhaustion at 4 m water depth with either normal air or oxygen-enriched air (40% O2) in a double-blind, randomized within-subject design. Heart rate and ventilation were measured throughout the dive and maximum whole blood lactate samples were determined post-exercise. ANOVAs showed a significant effect for the factor breathing gas (F(1, 9)=7.52; P=0.023; η2 p=0.455), with a lower ventilation for oxygen-enriched air during fin-swimming velocities of 0.6 m·s-1 (P=0.032) and 0.8 m·s-1 (P=0.037). Heart rate, lactate, and time to exhaustion showed no significant differences. These findings indicate decreased ventilation by an elevated oxygen fraction in the breathing gas when fin-swimming in shallow-water submersion with high velocity (>0.5 m·s-1). Applications are within involuntary underwater exercise or rescue scenarios for all dives with limited gas supply.

A three-wave longitudinal study on the relation between commuting strain and somatic symptoms in university students: exploring the role of learning-family conflicts.

BACKGROUND: We examine the role of learning-family conflicts for the relation between commuting strain and health in a sample of medical university students. The first goal of the study was to investigate the mediating role of learning-family conflicts. The second goal was to extend the temporal view on relations between study variables. Therefore, we differentiated long-term systematic change among variables over a period of two-years from a dynamic perspective with repeated commuting events on the individual level of analyses. METHODS: We applied a multilevel research design and collected survey data from 128 medical students on three points in time (N = 339 measurement points). Participants informed about commuting strain, learning-family conflicts, somatic symptoms, as well as commuting distance and time. RESULTS: Bayesian multilevel analyses showed that results differed with regard to level of analysis: while learning-family conflicts mediated the relation between commuting strain and somatic symptoms on a systematic aggregation-level perspective of analysis (indirect effect estimatebetween = 0.13, SE = .05, 95% CI [0.05; ∞), Evidence Ratio = 250.57), this was not the case on the dynamic event perspective (indirect effect estimatewithin = 0.00, SE = 0.00, 95% CI [- 0.01; ∞), Evidence Ratio = 0.84). CONCLUSIONS: We demonstrated that learning-family conflicts explain why commuting may have unfavorable effects on health for medical students. We also showed that it is the long-term commuting experience that is related to health complaints and not the single commuting event. This means that short-term deviations from general levels of commuting strain do not cause somatic symptoms, but general high levels of commuting strain do instead.

An Updated Narrative Review on Ergometric Systems Applied to Date in Assessing Divers' Fitness.

Many recreational divers suffer medical conditions, potentially jeopardizing their safety. To scale down risks, medical examinations are mandatory and overwhelmingly performed using bicycle ergometry, which overlooks some important aspects of diving. Searching ergometric systems that better address the underwater environment, a systematic literature search was conducted using the keywords 'diving', 'fitness', 'ergometry', and 'exertion'. All presented alternative systems found convincingly describe a greatly reduced underwater physical performance. Thus, if a diver's workload in air should already be limited, he/she will suffer early from fatigue, risking a diving incident. How to assess fitness? Performance diagnostics in sports is always specific for a modality or movement. Therefore, professional scuba divers should be tested when fin-swimming underwater. For the vast number of recreational divers, the current screening can likely not be replaced. However, to prevent accidents, divers need to understand and be able to improve factors that limit their physical performance underwater. Other systems, presented here, will continue to be important tools in underwater research.

Students' perspectives on interventions to reduce stress in medical school: A qualitative study.

The mental health of medical students remains to be a matter of concern. Numerous setting-based and individual-based interventions for student mental health have been proposed in the literature. However, the student perspective on those interventions has been largely neglected. This study aims to explore how medical students perceive different interventions and if they desire any additional changes with regard to their studies. Eight focus groups with 71 participants were conducted at a large German medical school. Focus groups were recorded, transcribed and content-analyzed using MAXQDA 18. We found that medical students prefer setting-based interventions. Most proposed interventions were on a setting-based level. For instance, students asked for more information on the university's psychosocial counseling services and for better information management regarding contact persons. Interventions proposed in the literature received mixed reactions: Several participants did not favour a pass/fail grading system. Students considered a peer-to-peer mentoring program for freshmen very helpful. Students had diverse attitudes towards Balint groups. They approved of several self-management courses, most of them being related to time or stress management. Interestingly, the most urgently wanted interventions appear to be rather easy to implement (e.g. a mentoring program). This study explored the medical student perspective on student mental health interventions. Additionally, our study illustrates the benefit and feasibility of involving students early on in the conception of interventions. Further research with a representative sample is needed to obtain broader information on the acceptance of the suggested interventions.

Assessment of a dive incident using heart rate variability.

INTRODUCTION: Scuba diving likely has an impact on the autonomic nervous system (ANS). In the course of conducting trials of underwater ECG recording for measurement of heart rate variability, there was an unexpected stressful event; one participant's regulator iced and began to free-flow. METHODS: A custom-made, water- and pressure-tight aluminum housing was used to protect a portable Holter monitor. ECGs were recorded in three experienced divers who witnessed an unplanned moderately stressful incident during diving. The ECG signals were analysed for measures of heart rate variability (HRV). RESULTS: Analysis for different short-term HRV measures provided consistent results if periods of interest were appropriately time-aligned. There was improvement in sympatho-vagal balance. One diver unexpectedly exhibited an increase in both sympathetic and vagal activity shortly after the incident. CONCLUSIONS: A conventional open-water dive affected the ANS of experienced recreational divers as measured by HRV which provides a global evaluation of the ANS and alterations in its two branches. The heart rate variability data gathered from several participating divers around the time of this event illustrate the potential utility of this variable in quantifying stress during diving. HRV data may be useful in addressing relevant diving related questions such as effects of cold, exercise or different breathing gases on ANS function.

Does oxygen-enriched air better than normal air improve sympathovagal balance in recreational divers?An open-water study.

Effects of the hyperbaric environment on the autonomic nervous system (ANS) in recreational divers are not firmly settled. Aim of this exploratory study was to (1) assess ANS changes during scuba diving via recordings of electrocardiograms (ECG) and to (2) study whether nitrox40 better improves sympathovagal balance over air. 13 experienced divers (~40yrs) performed two open-water dives each breathing either air or nitrox40 (25m/39min). 3-channel ECGs were recorded using a custom-made underwater Holter-monitor. The underwater Holter system proved to be safe. Air consumption exceeded nitrox40 consumption by 12% (n = 13; p < 0.05). Both air and nitrox40 dives reduced HR (10 vs 13%; p < 0.05). The overall HRV (pNN50: 82 vs 126%; p < 0.05) and its vagal proportion (RMSSD: 33 vs 50%; p < 0.05) increased during the dive. Moreover, low (LF: 61 vs 47%) and high (HF: 71 vs 140%) frequency power were increased (all p < 0.05), decreasing the ratio of LF to HF (22 vs 34%). : Conventional open-water dives distinctly affect the ANS in experienced recreational divers, with sympathetic activation less pronounced than vagal activation thereby improving the sympathovagal balance. Nitrox40 delivered two positive results: nitrox40 consumption was lower than air consumption, and nitrox40 better improved the sympathovagal balance over air.

Stressors and resources related to academic studies and improvements suggested by medical students: a qualitative study.

BACKGROUND: Prior evidence suggests that medical students' mental health is poor and deteriorates during the course of academic studies. This qualitative study therefore aims to improve our understanding of medical students' perceptions of i) stressors related to their academic studies, ii) resources that may facilitate coping with those stressors and iii) suggestions to potentially reduce stress. METHODS: Eight focus groups were conducted with medical students enrolled at a medical school in Germany until thematic saturation was reached. A topic guide was used to facilitate the discussion. Subsequently, focus group discussions were transcribed and content-analyzed using MaxQDA. RESULTS: Organizational factors especially related to inadequate information flow as well as exams (e.g. repeat exams, scheduling, perceived unfair grading), poor theoretical and practical teaching quality, time and performance pressure, social interactions and individual characteristics (e.g. self-expectations, fear of failure) emerged as major contributors to stress. Resources perceived to facilitate coping with those stressors pertained to some other organizational aspects (e.g. flexibility, availability of contact persons), career prospects, practical training, social support, personal characteristics (e.g. knowledge base, past experience) and leisure time. Suggestions for improvement related primarily to organizational measures rather than individual-level measures. CONCLUSIONS: Besides well-known stressors (e.g. exams and high performance pressure), some new aspects emerged from our study including stress related to organizational factors and repeat exams. Accordingly, students' wishes for organizational-level interventions, including better information systems and better interweaving of practical and theoretical education, could be first target areas for improvement.

Medical students' perceptions of stress due to academic studies and its interrelationships with other domains of life: a qualitative study.

BACKGROUND: Medical students have been found to experience considerable stress due to their academic studies. The high demands associated with academic studies may interfere with demands in other domains of life. Conversely, demands in those other domains of life may conflict with academic studies. OBJECTIVE: We aimed to better understand the potential inter-relationships between the demands related to academic studies and in other domains of life. DESIGN: A total of 68 medical students from a medical school in Germany participate in eight focus groups. Sessions were structured by a topic guide and were recorded, transcribed and content-analyzed. RESULTS: Embarking on one's medical studies was perceived to be associated with important personal challenges, such as living alone for the first time and finding a new social role in one's peer group. Permanent stress was perceived to result in emotional exhaustion, which spilled over in other domains of life. Students reported to feel guilty if they did not spend their limited spare time on learning. Consequently, they felt to have little time for leisure time activities and a healthy lifestyle. Feelings of social isolation, especially during exam phases, were reported. Leisure activities were perceived to facilitate recovery from academic stress. Social ties were subjectively able to reduce stress, but also to increase stress due to demands. Side jobs were perceived to increase stress and to be time-consuming and were thus perceived to result in poorer academic performance. Certain personality characteristics seemed to amplify those perceptions. For instance, high levels of conscientiousness were felt to relate to higher expectations regarding one's academic performance and thus increased stress. CONCLUSION: The demands associated with medical studies, the demands in private life, lacking resources for recovery and certain personal traits as well as interactions between those domains can contribute to stress among medical students and reduce well-being.

The Relationship between Personality Traits with Depressive Symptoms and Suicidal Ideation among Medical Students: A Cross-Sectional Study at One Medical School in Germany.

Medical students are at increased risk of experiencing mental health problems. Certain personality traits may be associated with elevated vulnerability to study-related stress and poor mental health. This study aimed to investigate the relationship between such personality traits and mental health outcomes among medical students. We drew on cross-sectional data from 251 medical students who had been enrolled for one-year at a medical school in Germany. Depressive symptoms were measured using the Patient Health Questionnaire-8 (PHQ-8) and suicidal ideation was assessed by item 9 from the Patient Health Questionnaire-9 (PHQ-9). Personality traits were captured using the Business-Focused Inventory of Personality 6 Factors (BIP-6F). Multivariable logistic regression analyses were used to quantify the associations between work-related personality factors and mental health outcomes, controlling for demographic and social factors. Odds ratios (ORs) as outcome measures with 95% confidence intervals (CIs) were used. After controlling for important confounders, medical students who scored highly on Stability had lower odds of depressive symptoms (OR: 0.19, 95% CI: 0.09⁻0.42, p < 0.001) and suicidality (OR: 0.38, 95% CI: 0.16⁻0.87, p < 0.05) than those with high scores in other work-related personality factors. Findings also showed that those who scored highly on Dominance had greater odds of depressive symptoms (OR: 2.46, 95% CI: 1.22⁻4.97), p < 0.01). Work-related personality-informed interventions, which promote students' mental well-being and reduce academic stress should be considered at various stages of their medical training.

Elevated Psychosocial Stress at Work in Patients with Systemic Lupus Erythematosus and Rheumatoid Arthritis.

OBJECTIVE: Psychosocial stress at work not only affects the healthy working population, but also workers with chronic diseases. We aimed to investigate the psychosocial work stress levels in patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). METHODS: A cross-sectional study applied the Effort-Reward Imbalance (ERI) questionnaire - an internationally established instrument that measures work stress - to patients with SLE and RA who were capable of work and to a group of controls without these diseases. Participants were recruited through rheumatologists in private practices, hospitals, and from self-help groups by personal communication, paper-based flyers, and online advertisements. Because very few studies tested the ERI's applicability in patient groups, with a lack of evidence in patients with inflammatory rheumatic diseases, internal consistency and construct validity of the ERI measure were evaluated. RESULTS: Data came from 270 patients with RA and 247 with SLE, and 178 controls. Patients showed elevated psychosocial stress at work compared to controls. Across the total sample and all groups, satisfactory internal consistencies of the scales effort, reward, and overcommitment were obtained (Cronbach's alpha coefficients > 0.70), and confirmatory factor analysis replicated the theoretical structure of the ERI model (goodness-of-fit index > 0.80). CONCLUSION: We found elevated psychosocial stress at work in patients with SLE and RA compared to controls by applying the ERI model. Despite some heterogeneity in the sample, we achieved satisfactory psychometric properties of the ERI questionnaire. Our results suggest that the ERI questionnaire is a psychometrically useful tool to be implemented in epidemiological studies of employed patients with SLE and RA.

Student ERI: Psychometric properties of a new brief measure of effort-reward imbalance among university students.

BACKGROUND: Psychosocial stress among university students, particularly medical students, is considered a widely prevalent problem. There is a need for valid measurement of an adverse psychosocial stress environment in university settings. The aim of this study was to examine the psychometric properties of a newly developed short student version of the effort-reward imbalance (ERI) questionnaire in a sample of medical students. METHODS: A cross-sectional survey with a self-administrated questionnaire containing three scales was conducted among 406 medical students. Item-total correlations and Cronbach's alpha were calculated to assess the internal consistency of the scales. Confirmatory factor analysis was applied to test factorial validity of the questionnaire structure. RESULTS: The student version of the ERI questionnaire provides acceptable psychometric properties. The Cronbach's alpha coefficients for effort, reward, and over-commitment were 0.67, 0.65, and 0.79, respectively. Confirmatory factor analysis displayed a satisfactory fit of the data structure with the theoretical concept (GFI>0.94). CONCLUSIONS: This student version of the ERI questionnaire provides a psychometrically tested tool for studies focussing on psychosocial environment in university settings. Further applications of this approach in other student groups are needed, in addition to prospective studies assessing associations with health outcomes.

"Lung packing" in breath hold-diving: An impressive case of pulmo-cardiac interaction.

There is a complex interaction between the heart and the lungs. We report on a healthy female who performs breath hold diving at a high, international level. In order to optimize pressure equalization during diving and to increase oxygen available, apneists employed a special breathing maneuver, so called "lung packing". Based on cardiac MRI we could demonstrate impressive effects of this maneuver on left ventricular geometry and hemodynamics. Beyond the fact, that our findings support the concept of pulmonary -cardiac interrelationship, it should be emphasized, that the reported, extreme breathing maneuver could have detrimental consequences due to reduction of stroke volume and cardiac output.