Biomathematical modeling of fatigue due to sleep inertia.

Biomathematical models of fatigue capture the physiology of sleep/wake regulation and circadian rhythmicity to predict changes in neurobehavioral functioning over time. We used a biomathematical model of fatigue linked to the adenosinergic neuromodulator/receptor system in the brain as a framework to predict sleep inertia, that is, the transient neurobehavioral impairment experienced immediately after awakening. Based on evidence of an adenosinergic basis for sleep inertia, we expanded the biomathematical model with novel differential equations to predict the propensity for sleep inertia during sleep and its manifestation after awakening. Using datasets from large laboratory studies of sleep loss and circadian misalignment, we calibrated the model by fitting just two new parameters and then validated the model's predictions against independent data. The expanded model was found to predict the magnitude and time course of sleep inertia with generally high accuracy. Analysis of the model's dynamics revealed a bifurcation in the predicted manifestation of sleep inertia in sustained sleep restriction paradigms, which reflects the observed escalation of the magnitude of sleep inertia in scenarios with sleep restriction to less than âˆ¼ 4 h per day. Another emergent property of the model involves a rapid increase in the predicted propensity for sleep inertia in the early part of sleep followed by a gradual decline in the later part of the sleep period, which matches what would be expected based on the adenosinergic regulation of non-rapid eye movement (NREM) sleep and its known influence on sleep inertia. These dynamic behaviors provide confidence in the validity of our approach and underscore the predictive potential of the model. The expanded model provides a useful tool for predicting sleep inertia and managing impairment in 24/7 settings where people may need to perform critical tasks immediately after awakening, such as on-demand operations in safety and security, emergency response, and health care.

Perceptions of bias in HIV prevention services, happiness with social support, and anticipated PrEP stigma among Black and Latine/x sexual and gender diverse individuals.

Although pre-exposure prophylaxis (PrEP) is a highly effective preventive treatment for HIV, anticipated PrEP stigma can hinder uptake. Perceptions of bias in HIV prevention and evaluations (e.g., happiness) tied to social support among Black and Latine/x sexual and gender diverse (SGD) individuals could be important correlates of anticipated PrEP stigma. To further this line of inquiry, a national sample of 872 Black and Latine/x SGD individuals who had and had never taken PrEP (Mage = 25.1, SD = 2.8) reported how they perceived HIV prevention and how happy they were with their social support. Multivariable linear regressions revealed that greater perceptions of bias in HIV prevention services were associated with higher anticipated PrEP stigma among Black and Latine/x SGD individuals who have never taken PrEP. Greater happiness with friend support was associated with lower PrEP stigma, whereas greater happiness with family support was associated with higher PrEP stigma among individuals who have taken PrEP. Findings highlight the need for PrEP and HIV interventions to address the intersectional stigma attached to prevention and for researchers to understand how evaluations of social support may contribute to stigma among Black and Latine/x SGD individuals.

Stress of being outed to parents, LGBTQ family support, and depressive symptoms among sexual and gender diverse youth.

Limited scholarship has explored how a lack of agency in identity disclosure (being "outed") to parents is associated with mental health experiences of sexual and gender diverse youth (SGDY). With a national sample of SGDY (N = 9272; 66.8% White non-Hispanic) aged 13-17 (Mage = 15.63, SD = 1.24), this study first compared social position differences between SGDY who were outed to their parents compared to those not outed, and second, investigated how the stress from being outed to parents was associated with LGBTQ family support and depressive symptoms. Results revealed that SGDY who were outed to their parents reported higher levels of depressive symptoms and lower amounts of LGBTQ family support than SGDY who were not outed to their parents. In addition, greater stress from being outed to parents was indirectly associated with higher depressive symptoms through lower LGBTQ family support. These relationships significantly varied across gender identity. Findings highlight the importance of instilling greater agency in disclosure experiences among SGDY.

Sexual Minority Youth Reporting SOGIE-Based Harassment to Adults at School: The Roles of Experienced Harassment, Outness, Safety, and Adult Support at School.

Despite a proliferation of bullying prevention programs in recent time, limited work has investigated support-seeking behaviors in response to elevated bullying levels among sexual minority youth (SMY). To address this gap, the current study examined how harassment targeting SOGIE (sexual orientation, gender identity, and gender expression), sexual identity outness, school safety, and perceptions of teacher/staff support were associated with SMY talking to an adult at school about harassment. A large contemporary national sample of SMY (N = 5538) between the ages 13-18 (Mage = 15.53, SD = 1.33) who experienced at least one form of SOGIE-based harassment in the past year was leveraged for analyses. Hierarchical multivariable logistic regressions revealed more frequent SOGIE-based harassment was associated with greater odds of reporting harassment to school personnel, particularly among SMY who felt safe at school. Findings highlight the need for school-based interventions to foster school safety among SMY who experience peer harassment to promote their reporting of this behavior.

Fatigue risk management based on self-reported fatigue: Expanding a biomathematical model of fatigue-related performance deficits to also predict subjective sleepiness.

Biomathematical models of fatigue can be used to predict neurobehavioral deficits during sleep/wake or work/rest schedules. Current models make predictions for objective performance deficits and/or subjective sleepiness, but known differences in the temporal dynamics of objective versus subjective outcomes have not been addressed. We expanded a biomathematical model of fatigue previously developed to predict objective performance deficits as measured on the Psychomotor Vigilance Test (PVT) to also predict subjective sleepiness as self-reported on the Karolinska Sleepiness Scale (KSS). Four model parameters were re-estimated to capture the distinct dynamics of the KSS and account for the scale difference between KSS and PVT. Two separate ensembles of datasets - drawn from laboratory studies of sleep deprivation, sleep restriction, simulated night work, napping, and recovery sleep - were used for calibration and subsequent validation of the model for subjective sleepiness. The expanded model was found to exhibit high prediction accuracy for subjective sleepiness, while retaining high prediction accuracy for objective performance deficits. Application of the validated model to an example scenario based on cargo aviation operations revealed divergence between predictions for objective and subjective outcomes, with subjective sleepiness substantially underestimating accumulating objective impairment, which has important real-world implications. In safety-sensitive operations such as commercial aviation, where self-ratings of sleepiness are used as part of fatigue risk management, the systematic differences in the temporal dynamics of objective versus subjective measures of functional impairment point to a potentially significant risk evaluation sensitivity gap. The expanded biomathematical model of fatigue presented here provides a useful quantitative tool to bridge this previously unrecognized gap.

Sleep restriction and degraded reaction-time performance in Figaro solo sailing races.

In solo offshore sailing races like those of the Solitaire du Figaro, sleep must be obtained in multiple short bouts to maintain competitive performance and safety. Little is known about the amount of sleep restriction experienced at sea and the effects that fatigue from sleep loss have on sailors' performance. Therefore, we assessed sleep in sailors of yachts in the Figaro 2 Beneteau class during races and compared response times on a serial simple reaction-time test before and after races. Twelve men (professional sailors) recorded their sleep and measured their response times during one of the three single-handed races of 150, 300 and 350 nautical miles (nominally 24-50 h in duration). Total estimated sleep duration at sea indicated considerable sleep insufficiency. Response times were slower after races than before. The results suggest that professional sailors incur severe sleep loss and demonstrate marked performance impairment when competing in one- to two-day solo sailing races. Competitive performance could be improved by actively managing sleep during solo offshore sailing races.

Examining Mental Health and Bullying Concerns at the Intersection of Sexuality, Gender, Race, and Ethnicity Among a National Sample of Sexual and Gender Diverse Youth.

Purpose: Most extant scholarship that examines the health experiences of sexual and gender diverse youth (SGDY) is limited in the ability to apply an intersectional framework due to small sample sizes and limitations in analytic methods that only analyze the independent contribution of social identities. To address this gap, this study explored the well-being of youth at the intersection of ethnic, racial, sexual, and gender identities in relation to mental health and bullying. Methods: Data were from a U.S. national survey of SGDY aged 13-18 years, collected in 2022 (N = 12,822). Exhaustive Chi-square Automatic Interaction Detection analysis identified intersectional social positions bearing the greatest burden of negative health-related experiences (depression, anxiety, and past 30-day in-person victimization). Results: Transgender boys were among those at the highest prevalence for compromised mental health and peer-based in-person victimization. Although the primary distinguishing factor was transgender identity for depression and anxiety, there were no racial/ethnic distinctions, corroborating some previous scholarship. Asian cisgender and transgender girl SGDY shared the lowest burden of peer-based in-person victimization in school. Conclusion: Our findings suggest a need for scholars, health professionals, and other stakeholders to better understand the mechanisms that drive negative health experiences and in-person victimization experiences at the intersections of sexual, gender, racial, and ethnic identities.

Tracheostomy insertion in COVID-19: insertion practice and factors leading to unplanned tube exchange.

Background: Tracheostomy insertion in patients with coronavirus disease 2019 (COVID-19) presents unique challenges. Patients frequently have high ventilatory requirements, and as an aerosol generating procedure, tracheostomy insertion creates the potential for staff transmission. Problems with tracheostomies contribute to morbidity and mortality, and tracheostomy changes may increase risks of staff transmission. We sought to quantify the incidence of clinically necessitated tracheostomy changes, establish the indications for change and investigate the incidence of staff transmission. Methods: We conducted a single institution, retrospective, observational cohort study of all intensive care unit (ICU) patients with COVID-19 who had a tracheostomy between March 2020 and April 2021. The institution is a large tertiary referral centre in Ireland. Results: Forty-three patients had a tracheostomy during the study period. All were a Shiley™ Flexible Adult Taperguard or Shiley™ XLT Tracheostomy. 14 patients (33%) required a tracheostomy change, with the majority (57%) involving a change from a standard size to an extended length tracheostomy. Persistent leak was the most common indication for change (71.6%). Other indications included patient-ventilator dyssynchrony, persistent cough and accidental decannulation. No staff transmission of COVID-19 occurred during this study. Conclusions: The incidence of tracheostomy change was 33%, highlighting the importance of selecting the right tracheostomy for each patient. We discuss how key characteristics of tracheostomies such as type, size, length and inner diameter may impact flow, resistance and work of breathing, leading to unplanned tracheostomy change. No staff transmission occurred arising from tracheostomy insertion, adding to increasing evidence that tracheostomy insertion in COVID-19 appears safe with adherence to guidelines describing the correct use of personal protective equipment.

Anaesthesia for reconstructive free flap surgery for head and neck cancer.

Head and neck cancer surgery presents significant challenges for the anaesthetist. A thorough multidisciplinary preoperative assessment and optimisation of the patient is essential, including nutritional and psychological evaluation. The incidence of a difficult airway is high, and the anaesthetist must be skilled in advanced airway techniques. Surgery is extensive, often requiring reconstructive surgery with either a pedicled or free flap. Detailed knowledge of flap physiology and anatomy is needed, and anaesthesia comprises careful management of mean arterial pressure, fluid administration, temperature control and oxygenation. The Enhanced Recovery after Surgery Society and the Society for Head and Neck Anaesthesia consensus recommendations provide guidance on current best practice. Despite continued debate, it now appears that this constitutes goal-directed fluid therapy, coupled with judicious vasopressor therapy sufficient to achieve an adequate mean arterial pressure. Emerging techniques such as prehabilitation and postoperative near-infrared spectroscopy flap monitoring provide hope of improved outcomes going forward.

A Simulation-Based Training Program in Rapid Sequence Induction for Novice Anesthesiology Trainees Using a Novel Checklist.

Background: The novice anesthesiology trainee is required to assimilate the technical and nontechnical skills required to safely perform a rapid sequence induction (RSI). Acquisition of this core competency is traditionally achieved using operating room-based experiential learning, which may be associated with significant gaps in early trainee preparation. We conducted a study to explore the role of a new, customized, high-fidelity simulation-based training program designed to address this gap in RSI training. We then assessed mean performance scores of participants in the simulator and 4 weeks later. Methods: This observational study assessed participants' performance in the simulator on the day of training and in the workplace 4 weeks later. There is no universally agreed checklist or cognitive aid incorporating nontechnical skills and planning for unanticipated difficult airway management in RSI, so we applied a new scoring checklist developed by 6 experts using the modified Delphi technique. Results: Our task scoring checklist included nontechnical skills and consisted of 37 weighted parameters with a maximum performance score of 171. On the day of training, mean performance score was 105 (SD of 16). At the workplace evaluation 4 weeks after simulation training, the mean performance score of participants had increased to 140 (SD of 14.5; P = .001). The 95% confidence intervals for the simulator and workplace participant scores were 92 to 118 and 128 to 152, respectively. Conclusions: The results suggest that this simulation-based training in RSI was associated with an improvement in RSI performance in novice trainees and may complement the current system of workplace-based training.

Acute respiratory failure in immunosuppressed patients admitted to ICU.

INTRODUCTION: The number of hospitalized immunosuppressed adults is a growing and often develop severe complications that require admission to an Intensive Care Unit (ICU). The main cause of admission is acute respiratory failure (ARF). The goal of the study was to determine if ARF represents an independent risk factor for hospital mortality and in particular, we sought to ascertain if any risk factors were independently and identifiably associated with a bad outcome. METHODS: We perform a retrospective study of a prospectively collected data from patients admitted to an ICU. Adult patients with known immunosuppressive condition admitted to ICU were included. RESULTS: A total of 248 patients were included. Of 248 patients, 117 (47.2%) had a diagnosis of ARF at the time of ICU admission. Patients with ARF had a significantly higher in-hospital mortality (53.4% vs. 28.2% p = 0.001). Factors independently associated with hospital mortality were diagnosis of ARF at ICU admission, the presence of septic shock, use of continuous renal replacement therapy and failure of high-flow nasal canula(HFNC)/non-invasive (NIV) respiratory therapies. CONCLUSION: We identified ARF on admission and failure of HFNC/NIV to be independently associated with increased hospital mortality in immunosuppressed patients.

A new mathematical model for the homeostatic effects of sleep loss on neurobehavioral performance.

The two-process model of sleep regulation makes accurate predictions of sleep timing and duration for a variety of experimental sleep deprivation and nap sleep scenarios. Upon extending its application to waking neurobehavioral performance, however, the model fails to predict the effects of chronic sleep restriction. Here we show that the two-process model belongs to a broader class of models formulated in terms of coupled non-homogeneous first-order ordinary differential equations, which have a dynamic repertoire capturing waking neurobehavioral functions across a wide range of wake/sleep schedules. We examine a specific case of this new model class, and demonstrate the existence of a bifurcation: for daily amounts of wakefulness less than a critical threshold, neurobehavioral performance is predicted to converge to an asymptotically stable state of equilibrium; whereas for daily wakefulness extended beyond the critical threshold, neurobehavioral performance is predicted to diverge from an unstable state of equilibrium. Comparison of model simulations to laboratory observations of lapses of attention on a psychomotor vigilance test (PVT), in experiments on the effects of chronic sleep restriction and acute total sleep deprivation, suggests that this bifurcation is an essential feature of performance impairment due to sleep loss. We present three new predictions that may be experimentally verified to validate the model. These predictions, if confirmed, challenge conventional notions about the effects of sleep and sleep loss on neurobehavioral performance. The new model class implicates a biological system analogous to two connected compartments containing interacting compounds with time-varying concentrations as being a key mechanism for the regulation of psychomotor vigilance as a function of sleep loss. We suggest that the adenosinergic neuromodulator/receptor system may provide the underlying neurobiology.

Fatiguing effect of multiple take-offs and landings in regional airline operations.

Fatigue is a risk factor for flight performance and safety in commercial aviation. In US commercial aviation, to help to curb fatigue, the maximum duration of flight duty periods is regulated based on the scheduled start time and the number of flight segments to be flown. There is scientific support for regulating maximum duty duration based on scheduled start time; fatigue is well established to be modulated by circadian rhythms. However, it has not been established scientifically whether the number of flight segments, per se, affects fatigue. To address this science gap, we conducted a randomized, counterbalanced, cross-over study with 24 active-duty regional airline pilots. Objective and subjective fatigue was compared between a 9-hour duty day with multiple take-offs and landings versus a duty day of equal duration with a single take-off and landing. To standardize experimental conditions and isolate the fatiguing effect of the number of segments flown, the entire duty schedules were carried out in a high-fidelity, moving-base, full-flight, regional jet flight simulator. Steps were taken to maintain operational realism, including simulated airplane inspections and acceptance checks, use of realistic dispatch releases and airport charts, real-world air traffic control interactions, etc. During each of the two duty days, 10 fatigue test bouts were administered, which included a 10-minute Psychomotor Vigilance Test (PVT) assessment of objective fatigue and Samn-Perelli (SP) and Karolinska Sleepiness Scale (KSS) assessments of subjective sleepiness/fatigue. Results showed a greater build-up of objective and subjective fatigue in the multi-segment duty day than in the single-segment duty day. With duty start time and duration and other variables that could impact fatigue levels held constant, the greater build-up of fatigue in the multi-segment duty day was attributable specifically to the difference in the number of flight segments flown. Compared to findings in previously published laboratory studies of simulated night shifts and nighttime sleep deprivation, the magnitude of the fatiguing effect of the multiple take-offs and landings was modest. Ratings of flight performance were not significantly reduced for the simulated multi-segment duty day. The US duty and flight time regulations for commercial aviation shorten the maximum duty duration in multi-segment operations by up to 25% depending on the duty start time. The present results represent an important first step in understanding fatigue in multi-segment operations, and provide support for the number of flight segments as a relevant factor in regulating maximum duty duration. Nonetheless, based on our fatigue results, a more moderate reduction in maximum duty duration as a function of the number of flight segments might be considered. However, further research is needed to include investigation of flight safety, and to extend our findings to nighttime operations.

Dynamic circadian modulation in a biomathematical model for the effects of sleep and sleep loss on waking neurobehavioral performance.

Recent experimental observations and theoretical advances have indicated that the homeostatic equilibrium for sleep/wake regulation--and thereby sensitivity to neurobehavioral impairment from sleep loss--is modulated by prior sleep/wake history. This phenomenon was predicted by a biomathematical model developed to explain changes in neurobehavioral performance across days in laboratory studies of total sleep deprivation and sustained sleep restriction. The present paper focuses on the dynamics of neurobehavioral performance within days in this biomathematical model of fatigue. Without increasing the number of model parameters, the model was updated by incorporating time-dependence in the amplitude of the circadian modulation of performance. The updated model was calibrated using a large dataset from three laboratory experiments on psychomotor vigilance test (PVT) performance, under conditions of sleep loss and circadian misalignment; and validated using another large dataset from three different laboratory experiments. The time-dependence of circadian amplitude resulted in improved goodness-of-fit in night shift schedules, nap sleep scenarios, and recovery from prior sleep loss. The updated model predicts that the homeostatic equilibrium for sleep/wake regulation--and thus sensitivity to sleep loss--depends not only on the duration but also on the circadian timing of prior sleep. This novel theoretical insight has important implications for predicting operator alertness during work schedules involving circadian misalignment such as night shift work.