published_or_final_version / Nursing Studies / Master / Master of Nursing

Hyperglycaemia in critical care is common and has been linked to increased mortality and morbidity. Tight control of blood glucose concentrations to more normal levels can significantly reduce the negative outcomes associated with hyperglycaemia. However, hypoglycaemia and glycaemic variability have also been independently shown to increase mortality in critically ill patients. Further complicating the matter, critically ill patients exhibit high inter- and intra patient metabolic variability and thus consistent, safe control of glycaemia has proved very difficult. Model-based and model-derived tight glycaemic control methods have shown significant ability to provide very tight control with little or no hypoglycaemia in the intensive care unit (ICU). The model-based control practised in the Christchurch Hospital ICU uses a physiological model that relies on a single, time-varying parameter, SI, to capture the patient-specific glycaemic response to insulin. As an identified parameter, SI is prone to also capturing other, unintended, dynamics that add variability on multiple timescales. The objective of this research was to enable enhanced glycaemic control by addressing this variability of the SI parameter through better modelling and implementation. An improved model of insulin secretion as a function of blood glucose concentration was developed using data collected from a recent study at the Christchurch Hospital ICU. Separate models were identified for non-diabetic patients and diagnosed, or suspected type II diabetic patients, with R2 = 0.61 and 0.69, respectively. The gradients of the functions identified were comparable to data published in a number of other studies on healthy and diabetic subjects. The transcapilliary diffusion (nI) and cellular clearance (nC) rate parameters were optimised using data from published microdialysis studies. Interactions between these key parameters determine maximum interstitial insulin concentrations available for glucose disposal, and thus directly influence SI. The optimal values of these parameters were determined to be nI = nC = 0.0060 1/min. Models of endogenous glucose production (EGP), as functions of blood glucose concentration and time, were assessed. These models proved unsatisfactory due to difficulties in identifying reliable functions with the available data set. Thus, it was determined that EGP should continue to be treated as a population constant, except during real-time glycaemic control, where the value may be adjusted temporarily to ensure valid SI values. The first 24 hours of ICU stay proved to be a period of significantly increased SI variability, both in terms of hour-to-hour changes and longer-term evolution of level. This behaviour was evident for the entire study cohort as a whole and was particularly pronounced during the first 12-18 hours. The subgroup of cardiovascular surgery patients, in which there was sufficient data for analysis, mirrored the results of the whole cohort, but was found to have even lower and more variable SI. Glucocorticoid steroids were also found to be associated with clinically significant reductions in overall level and increases in hour-to-hour variability of SI. To manage variability caused by factors external to the physiological model, the use of several stochastic models was proposed. Using different models for the early part of ICU stay and for different diagnostic subgroups as well as when patients were receiving certain drug therapies would permit control algorithms to reduce the impact of the SI variability on outcome glycaemia. The impact of measurement timing and BG concentration errors on the variability of SI was assessed. Results indicated that the impact of both sources of errors on SI level was unlikely to be clinically significant. The impact of BG sensor errors on hour-to-hour SI variability was more pronounced. Understanding the effect of sensor and timing errors on SI allows their impact to be reduced by using the 5-95 percentile forecast range of stochastic models during glycaemic control. The performance of the model incorporating the proposed insulin kinetic parameters and secretion enhancements was validated for clinical glycaemic control and virtual trial purposes. This validation was conducted by self- and cross validation on a cohort independent to that with which the model was developed. The use of multiple stochastic models to reduce the impact of this extrinsic variability during glycaemic control was validated using virtual trials.

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This thesis describes a qualitative enquiry into the experiences of families visiting an adult intensive care unit (ICU) during a critical illness of a family member and nurses’ perceptions of families in this environment. A Grounded Theory approach was taken. Nine families (12 adults, 12 young people) with a family member in intensive care and twenty intensive care nurses in five focus groups contributed their experiences to the study through group interviews. Families described the admission of a family member as a traumatic event. The core experiences of families which emerged in the study revolved around uncertainty. Drawing on Davis’ (1963/1991, 1966) concepts of ‘clinical uncertainty’ and ‘functional uncertainty’ a number of strategies families and young people developed in dealing with the situation were identified. ‘Clinical uncertainty’ captures the unknown and unknowable aspects of critical illness. The ‘Functional uncertainty’ category emerged later in the research process and brings to light management of information disclosure for functional gain as a communication strategy. Functional uncertainty was identified in communications between nurses and families and between parents and children within families. Moreover, young people used the same ‘functional uncertainty’ strategy when disclosing information to peers within the school environment. ‘Keeping normality in life’ and ‘fishing for information’ and the associated strategies were identified as direct responses of young people to clinical and functional uncertainty. The strategies identified provide new insights into how young people process a critical illness event in their families. This emphasises the importance of listening to young people’s voices and the need to include young people in future studies. ‘Nursing in public’ emerged as an overarching theme within the data from nurses’ interviews. The contrasting interests of nurses and families in the context of critical illness became evident when open visiting policies were discussed. The promotion by policy makers and nursing scholars of a patient centred health care service and thus the implicit integration of families into care challenges nurses to adapt their working practices. Whilst this study provides evidence for the importance of integrating families into care it also shows the needs of nurses are in danger of being marginalised. Respecting the needs of families and nurses the question becomes how best to balance the competing needs of both groups. It is suggested that a ‘partnership in care’ approach which is firmly based on negotiations between nurses and families under the leadership of nurses will allow for the emergence of family care in intensive care, to the benefit of patients, families and nurses.

Driven by research studies and national targets, sedation practices in Intensive care Units (ICU) are undergoing change. Traditionally, ventilated patients in ICUs were kept deeply sedated and only gradually ‘weaned off’ sedation. However, current evidence supports a more ‘wakeful’ patient with the introduction of ‘sedation holds’ encouraging them to regain consciousness (Kress et al. 2000). There is little research exploring ICU nurses’ assessment and management of sedation. Employing a Heideggerian, hermeneutic phenomenological approach to enquiry, the study sought to provide insights into the world of the critical care nurse, nursing with technology, and specifically their beliefs surrounding sedation practices and how organisational factors, knowledge and personal experiences influence their clinical decisions in the care of the ventilated patient. The setting was the Royal Infirmary of Edinburgh, ICU and the purposive sample consisted of 16 ICU nurses with diverse critical care nursing experience. Bedside interviews, utilising an aide memoir, elicited narratives about the nurses’ experiences of sedation practice and a novel sedation monitor (responsiveness). The phenomenological analysis drew upon a number of existing frameworks to guide enquiry. The researcher engaged with the ‘hermeneutic circle’, acknowledging her pre-understandings and using these as a platform to move between the whole of the research and the parts, the descriptions and narratives offered, to develop new knowledge. Themes emerged that demonstrated patients’ sedation status directly impacted upon the nurses’ ICU lived experiences and left them in a state of disequilibrium regarding the requirement to deliver research based care, the desire to deliver holistic care and the duty to deliver safe care. The nurses perceived sedation holds and ‘wakefulness’ as resulting in patient agitation and distress which affected patient safety and comfort. However, the nurses equally felt a pressure of obligation to the doctors to perform such evidence based sedation holds. They described the struggling to maintain patient safety and manage their own fears and anxieties and organisational constraints, whilst experiencing guilt, blame and failure associated with their behavioural discordance with the prescribed decisions and their own clinical decision making processes and strategies. Team work between the two professions and effective leadership is evidently less than ideal. Consequently the implementation of changes in sedation practice is failing to meet either the national targets or to respond to the nurses’ concerns regarding their patient’s short term wellbeing. On both counts this potentially impairs the pursuit of best practice.

Early intensive behavioral intervention (EIBI) is currently the most studied and most practiced intervention for children with autism spectrum disorder. There has been increasing evidence supporting the use of EIBI, but there have been limited evaluations of the effectiveness of EIBI intensity. The current study addressed this gap using data obtained from St.Amant Autism Program and comparing children receiving an average of 22 and 30 hours per week for a period of one year. Significant main effects of time were found for standardized measures of cognitive functioning, adaptive functioning, and autism severity. Future research should aim to address this research question with a larger sample size and a low-intensity control group. / May 2016

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg in partial fulfilment of the requirements for the degree of Master of Science in Nursing Johannesburg, 2017 / The purpose of this study was to describe the role of specialist nurses in mechanical ventilation management. The intention of the study was also to make recommendations for clinical practice and education of intensive care nurses. The setting of the study was ten (n = 10) adult intensive care units of two public hospitals in the Gauteng province. Included were trauma ICUs, cardiothoracic ICU, coronary care ICUs, major burns ICU, major injuries ICU, neurosurgery ICU and multidisciplinary ICUs. A non-experimental, descriptive, quantitative and cross-sectional survey design was used to describe the specialist nurses role in ventilation management. The final sample comprised 110 (out of 165) respondents, which yielded a response rate of 66.6% for the study. Data were collected from specialist intensive care nurses using a validated questionnaire developed by Rose et al. (2011). Data was analysed using descriptive (frequencies, means and standard deviation) and comparative statistical tests using t-tests and Chi-square analysis. Testing was done at the 0.05 level of significance. Of the 165 surveys distributed, 110 were returned (response rate 66.6%). Ninety-seven percent stated that a 1:1 ratio was used for patients receiving mechanical ventilation. Eighty-nine percent reported ventilation education for nurses was provided during ICU orientation, and 86.4% indicated ICUs provided opportunities for on-going ventilation education. Eighty-six percent of nurses reported that they had not worked in ICUs with automated weaning modes. Fifty-nine percent stated that weaning protocols were present in ICUs, and 56.4% reported the presence of protocols for weaning failure. Most nurses agreed that nurses and doctors collaborated in key ventilation decisions, but not when decisions to extubate and initial ventilation settings are made. This study showed a marginal (2%) number of nursing autonomous input made in key ventilator decisions. Seventy percent of nurses in this study agreed that responsibility for ventilation decisions lies at the level of senior registrars and above, and in their absence, only senior nurses (>80%) were perceived to be responsible for key ventilator decisions. Regarding independent titrations of ventilator settings, without medical consultation, findings showed that nurses in this study reported a frequency of >50% of the time for titration of respiratory rate, tidal volume, decreasing pressure support, increasing pressure support, titration of inspiratory pressure and ventilation mode changes. The self-perceived nursing autonomy and influence in decision making revealed a median score of 7 out of 10 points, respectively. Nurses with higher levels of autonomy, influence in decision making and years of experience scores, frequently (>50% of the time) made independent changes to ventilation settings (p<0.05). Conversely, nurses with fewer years of experience scores, infrequently (<50% of the time) made independent changes to ventilation settings without first checking with the doctor. The study concludes that nurses to re-evaluate their role in ventilation management and focus on key ventilation settings, nurses could strengthen their contribution in the collaboration of key ventilator settings. Recommendations are made for clinical practice and education of specialist nurses. / MT2018