Recruitment and derecruitment (R/D) of airways is known to significantly influence mechanical properties of the respiratory system during artificial ventilation, particularly in states of lung injury. The prevailing view of this phenomenon treats airway R/D as a static function of pressure. Recent experimental and clinical data suggests that this is not the case, but rather that R/D is an inherently dynamic process. In order to quantitatively assess the dynamics of lung recruitment during mechanical ventilation we extended a mathematical model by Bates and Irvin (9) for the purpose of fitting experimental data. The model of the lung consists of a parallel network of flow pathways with identical resistive and elastic elements. Each pathway is allowed to be either open, whereby it accumulates flow and decreases overall lung stiffness, or closed, increasing lung elastance and not participating in ventilation. The pathways are characterized by unique critical closing and opening pressures, and opening and closing velocities, each chosen from probability distribution functions. The rate of transition between an open and closed state depends on the magnitude difference between the pressure in the respiratory system and each unit’s critical pressure times the airway’s opening or closing velocity constant. Since the exact form of the pressure dependence governing recruitment and derecruitment remains unknown we explored four model variants to predict how opening or closing behavior is altered in injury. The lung model was coupled with a computational model of a mechanical ventilator in order to simulate elastance changes following deep inflation (DI) at three levels of Positive End Expiratory Pressure (PEEP). Elastance measurements came from healthy or lung injured mice at 4, 14, 24 or 48 hours following intratracheal instillation of saline (control) or hydrochloric acid (injury). The Nelder and Mead simplex optimization method was used to minimize error between model variants and average experimental elastance for each condition. By comparing the residual error of the fits for each model, we have demonstrated that only one variant was able to recreate both the transient response to deep inflations and the response to static PEEP. In fitting the best model to data from individual mice we obtained estimates for parameters governing opening and closing behavior. Statistics and model sensitivity were determined for each parameter in every experimental condition. Comparison of parameter values between groups revealed a significant increase in closing and opening pressures from health to injury, which worsened with increasing injury severity. The progressive increase in critical pressures as injury worsens implicates surfactant deactivation as the likely cause of increased propensity for airway closing during acute lung injury.

The re-creation of a holistic narrative that integrates the pre- and post-injury self is integral to recovery following acquired brain injury (ABI). However, individuals may struggle with deficits in linguistic skills required for narrative, along with reduced functioning, feelings of grief, difficulties with cognition, and other communicative challenges. This mixed-methods study analyzed data gathered from six non-aphasic adult participants with ABI during semi-structured interviews and through assessments. Thematic analyses showed that individuals experience a change in their sense of self prevs. post-injury, reflected in their self-narratives, and that even clinically undiagnosed changes in speech, language, and communication are impactful. Results from linguistic analysis and assessments suggest a relationship among a person’s cognitive capacity, his/her sense of loss, and pre- vs. post-injury narrative of self speech rates. Participants spoke comparatively slower about their post-injury self, with those participants with higher feelings of loss showing a reduction in their speech rates comparatively more. / Graduate / 0290 / 0460 / 0382 / bje@uvic.ca

Tears to the anterior cruciate ligament (ACL) represent a serious sport injury that can be physically and psychologically debilitating for athletes. Recovery from ACL surgery is a six to nine month process, though the first four months of rehabilitation represents the key time of recovery. Thus, psychological interventions should occur during these first four months, but then examine athletes' psychological and physical functioning over the longer term. Past research has supported the efficacy of goal setting and imagery in helping athletes during their ACL recovery, and MSC has been shown to help athletes regulate emotions and improve their sport performance. MSC-based interventions, however, have not been examined in relation to injured athletes' psychological functioning and physical recovery. Thus, I examined the relative effects of three psychological interventions (i.e., GS, IM, and MSC) on athletes' post-ACL responses. Overall, I found no significant differences in the effects of GS, IM, or MSC on athletes' athletic identity, confidence in returning to sport, reinjury anxiety, stress related to sport injury, perceptions of ability to cope with injury, and subjective knee functioning. Although non-significant, athletes in the GS group showed slightly larger rates of change in their reinjury anxiety and cognitive appraisal compared to athletes in the IM and MSC groups, while athletes in the IM group showed slightly greater rates of change in subjective knee functioning compared to athletes in the GS and MSC groups. However, these results did not support the original hypotheses that athletes in the MSC group would demonstrate significantly greater outcomes compared to the GS and IM groups.

The combined use of alcohol and caffeine has been identified as a public health concern, and yet, our knowledge of this type of use and how it relates to the risk of incurring an alcohol-related injury remains limited. Study 1 is a systematic review examining and critically analyzing the literature on the combined use of alcohol with energy drinks and the risk of injury. Studies 2 and 3 use data from a controlled Emergency Department (ED) study that was collected over 1.5 years from 3 separate hospitals in British Columbia. There was a total of 2804 participants across the ages of 18-98. Given the strengths and limitations of these different methodologies, both case-crossover and case-control analyses were performed in order to test for consistency of results. Study 2 examined the temporal association between alcohol and caffeine and use (Alc+Caff) and the risk of injury, as well as the potential moderating role of risk-taking propensity and mediating role of Alc+Caff between risk-taking propensity and injury risk. The combined use of alcohol and caffeine was found to be associated with a higher risk of injury, even after controlling for dose of alcohol and caffeine, other substance use, location at time of injury, risk-taking propensity, and sociodemographic variables. Alcohol and caffeine use was also found to partially mediate the relationship between risk-taking propensity and injury. Study 3 examined gender differences in the risk-relationship of Alc+Caff use and injury by testing the interaction between gender and Alc+Caff use and then examining the risk of injury following Alc+Caff use separately for men and women. Women were found to have a significantly higher risk of injury following alcohol use and Alc+Caff use relative to men. These results were found in both the case-crossover and case-control analyses. The findings from these studies indicate a relationship between Alc+Caff use and an increased risk of injury, especially for women, which is supported by previous research. The results are supportive of differential low-risk drinking guidelines for men and women. The findings also offer a significant contribution to our knowledge base, as the use of standardized measures and inclusion of multiple confounding variables allowed for the examination of the unique effect of Alc+Caff use. Alc+Caff use is associated with an increased risk of injury that cannot solely be explained by increased alcohol consumption, other substance use, risk-taking propensity, location at time of injury, or sociodemographic factors. Based on the epidemiological criteria of causation, the findings contribute evidence supportive of an inference of causality between Alc+Caff use and injury. The results of the current studies also offer suggestions for future research needed in this area, and provide recommendations for policy prevention and intervention efforts to reduce the harm associated with this type of consumption. / Graduate / 2020-07-01

Student Number : 8801336R - M Dent research report - School of Oral Health (Dentistry) - Faculty of Health Sciences / The Johannesburg Hospital is a major referral centre for trauma in Johannesburg, and maxillofacial and oral surgery is one of the most utilized trauma and surgical departments at this Hospital. Mandibular fractures comprise the bulk of facial fractures treated; unit statistics on this type of fracture have been collected at intervals for thirty years. Data collection for the current report was undertaken to update statistics on mandibular fractures, and was undertaken over a six month period in 2004. This study assessed the epidemiology of mandibular fractures in 133 patients; concentrating on age, gender, race, mechanism and nature of injuries, site of fracture, treatment modalities and a cost analysis of surgical treatment. Black males in their 30’s made up the bulk of the study sample. A total of 203 fractures were noted, with a mean of 1.5 fractures per mandible; with angle fractures being the most commonly involved site (39%). Most patients sustained their injuries due to criminally motivated incidents. At least 75% of all fractures in this series were surgically treated. This report highlights some interesting trends that have changed over the last three decades, and attempts to offer some plausible explanations for this.

Faculty of Health Sciences School of Physiotherapy 9605675x lindsayharris912@hotmail.com / Coaches and athletes are continually searching for ways to gain the "competitive edge" and improve athletic performance. Ergogenic substances and procedures are used routinely at almost all competitive levels. Creatine has become one of the most popular nutritional supplements among athletes in recent times. There is evidence suggesting that there are side effects of creatine supplementation. These include renal stress/failure, muscle injury and cramping. While creatine supplementation has the potential to be a safe and effective nutritional aid, these potential side effects may lead to long term problems in athletes. The aim of the study was to determine whether creatine supplementation is associated with injury defined as cramping and muscle strains. This was done using a questionnaire. A questionnaire was developed to consist of three sections determining the player’s training program, incidence of injury and use of creatine supplementation, if any. A pilot study was conducted to establish the validity and reliability of the questionnaire, estimate the time for data collection and identify any unanticipated problems. First team rugby players between the ages of 16 and 19 selected from six competitively recognized rugby schools within the Gauteng Province were included in the study. Consent was obtained from the headmasters of the relevant schools, coaches, and parents/guardians. Questionnaires were completed with the researcher present to explain any part of the questionnaire, which the players did not understand. Data were analyzed using the odds ratio from a logistic regression. The results reveal that no association exists between creatine supplementation and muscle injury in the form of cramping and muscle strains. The subjects were not aware of creatine supplementation recommendations and as a result it was being taken inconsistently and haphazardly.

Cigarette smoking has been reported to be prevalent in military training populations, and associated with lower cardiorespiratory fitness and higher risk of training-related injury. However, it is unclear whether habitual smoking impairs development of physical fitness. It is possible that smoking-induced alterations in oxidative stress, inflammation and hormone balance may disrupt training adaptation in smokers. The aim of this programme of work was to identify the influences of smoking on physical performance adaptation, selected biomarkers and injury risk in a military trainee population. The first study established that habitual smokers comprised 48% of a cohort of 2087 trainees. Upon closer examination, both at entry (Study 2) and during 10 weeks of training (Study 3) smokers exhibited chronically elevated oxidative stress and, after commencement of training, evidence of significantly higher resting inflammation compared with non-smokers. Throughout the full duration of training, performance of smokers in military physical fitness tests was significantly worse than non-smokers (Study 4), but neither muscular adaptation nor physical performance improvement were impaired in smokers in the early stages (10-14 weeks) or over the full duration (26 weeks) of training. It was expected that smokers would experience greater acute inflammatory responses to exercise but neither these, nor hormonal responses, differed between smokers and non-smokers in response to consecutive days of military field exercise (Study 5). In addition to poorer physical performance in smokers, training-related injury incidence was higher in smokers than non-smokers, specifically injuries attributed to overuse (Study 6). Overall, smoking appears to cause some physiological alterations which, while not impairing adaptation to training, may have adverse implications on health outcomes. Although the specific underlying mechanisms are unclear, habitual smokers exhibit greater injury risk and typically lower physical fitness than non-smoking counterparts.

Women's Rugby Union has been through a period of transition, from the introduction of professional contracts, to the expansion of international 15-a-side and sevens competitions. Despite increased popularity and growth, little published literature has investigated the specific epidemiology and risk factors for injuries in women's rugby union. This research was undertaken to investigate the injury risk to elite female players in both the 15-a-side and sevens games. Chapter 4 presents an epidemiological study of match injuries in elite club level women's rugby union. The overall match injury incidence rate was 43 per 1000 player hours with a mean injury severity of 36 days. This incident rate is low compared to that of the male game. This suggests that sex specific research is preferable to accurately guide future practices and interventions. Chapter 5 investigates the epidemiology if injuries across 2 seasons, in an International women's squad. With an injury incidence rate of 128 per 1000 player-hours the results illustrate a similar incidence rate of injuries to those observed in men's International competitions but a significantly higher incidence rate when compared to women's club level. The impact of injury and illness on a squad's player availability is an important consideration both for the players' own performance and for the squad's performance. Chapter 6 investigates how environmental factors (e.g. short preparation period, weekly training load and the magnitude of the change in training load) contributed to the number of injuries sustained by an International squad in an intense period of training, prior to a World Cup tournament. Similarly, in Chapter 7, injuries sustained by a World Cup sevens training squad were monitored, across an intense period of training and competition. The high injury incidence rate of 187 per 1000 player-hours highlights the difference in injury risk between women and men, with environmental factors likely to have been a contributory factor. A sport still in transition, continued sex specific research is crucial to ensure the introduction of appropriate injury prevention strategies in women's rugby Union.

Trauma-induced secondary cardiac injury (TISCI) represents an under recognised complication of severe injury with haemorrhage. A limited number of clinical studies have supported the development of adverse cardiac events, such as arrhythmia, in association with biomarker proven TISCI. Pre-clinical studies using small animal models have provided insights into potential mechanisms and key effector molecules involved in the development of TISCI, but there remains a general lack of understanding regarding the in vivo functional implications of this indirect cardiac injury resulting from trauma-haemorrhage. This project aimed to investigate the implications of cardiac injury on myocardial systolic function. A robust, translatable model of TISCI was developed, which reflected the cardiac biomarker profile identified in clinical studies and, for the first time, demonstrated a significant, dose-dependent rise in Heart-type Fatty Acid Binding Protein (H-FABP) in response to trauma-haemorrhage. Non-invasive echocardiography was used to determine the acute myocardial response to injury and haemorrhage and also to assess the response of the left ventricle to resuscitation after an antecedent 60-minute period of trauma-haemorrhage. The functional studies presented here have enabled real time visualisation of the impact of trauma-haemorrhage upon systolic left ventricular function over 1 to 6 hours, both with and without resuscitation. Having established the trends in in vivo systolic function over time, further studies were then conducted to test the combination of adenosine, lidocaine and magnesium (ALM) as a cardiovascular rescue agent in TISCI. ALM, as an adjunct to fluid resuscitation, has shown great promise as a therapeutic agent which improves haemodynamic outcomes, reduces the volume of resuscitation fluid required and favours survival in the murine model of TISCI.

Disruption to the life narrative is a common long-term experience following acquired brain injury. It can lead to barriers in being able to fulfil roles and engage in daily activities and occupations. Disruption occurs not only for the person who sustains the brain injury, but is also an experience for significant others in their lives. This narrative study gathered participants’ personal ‘sense making’ of life events following such disruption. Extended narrative interviews were combined with a photo-elicitation technique for six people with acquired brain injury and six people who had a significant other in their life with an acquired brain injury, all living in a rural area. It involved discussion around the patterning of their daily activities and roles both pre and post injury. Narrative analysis led to individual case studies of barriers and opportunities to lives impacted by brain injury. Issues were highly individualised and whilst the rural context presented an advantageous place to live for some due to tranquillity, it was less advantageous for others. However, synthesis of findings across cases considered the narrative form produced by the twelve accounts. This revealed that individuals drew on attributes of previous roles and careers to construct meaning and manage their lives, even when they could no longer engage with past roles and careers. Approaches to self-management post injury appeared to follow a pattern of drawing on internal schema underpinned by values, skills and meaning of previous roles and careers. This constitutes a form of capital built up from life pre-injury that is being utilised to achieve health and wellbeing, which I have called ‘embodied occupational capital’. An opportunity to work with individuals whose lives are affected by acquired brain injury has been offered, by way of focusing on this ‘embodied occupational capital’ to empower them to make positive change.