published_or_final_version / Community Medicine / Master / Master of Public Health

Mechanical ventilation (MV) therapy has been utilised in the intensive care unit (ICU) for 50 years to treat patients with respiratory illness by supporting the work of breathing, providing oxygen and removing carbon dioxide. MV therapy is utilised by 30-50% of ICU patients, and is a major driver of increased length of stay, increased cost and increased mortality. For patients suffering from acute respiratory distress syndrome (ARDS), the optimal MV settings are highly debated. ARDS patients suffer from a lack of recruited alveoli, and the application of positive end expiratory pressure (PEEP) is often used to maintain recruitment to maximise gas exchange and minimise lung damage. However, determining what level of PEEP is best for the patient is difficult. In particular, it involves a complex trade off between patient safety and ventilation efficacy. Currently, no clinical protocols exist to determine a patient-specific “best” PEEP. Model-based approaches provide an alternative patient-specific method to help clinical diagnosis and therapy selection. In particular, model-based methods can utilise a mix of both engineering and medical principles to create patient-specific models. The models are used for optimising ventilation settings and providing greater physiological insight into lung status than is currently available. Two model-based approaches are presented here. First, a quasi-static, minimal model of lung mechanics is presented based solely on fundamental lung physiology and mechanics. Secondly, a model of dynamic functional residual capacity (dFRC) is developed and presented based on model-based status of lung stress and strain. These models are validated with retrospective clinical data to evaluate the potential of such model-based approaches. Finally, the models are further validated with real time clinical data over a broader spectrum of pressure-volume ranges than prior studies to evaluate the clinical viability of model-based approaches to optimise MV therapy. When validated with real-time clinical trials data, the outputs of the recruitment model provide a range of optimal patient-specific values of PEEP based on different clinically and physiologically derived criteria. The recruitment model is also shown to have the ability to track the disease state of ARDS over time. The dFRC model introduces the PEEP stress parameter, β, which represents a unique population constant. The dFRC model suggests that clinically reasonable estimates of dFRC can be achieved by using this novel value of β, rather than the current, potentially hazardous, methods of deflating the lung to atmospheric pressure. Finally, a third model, combining the principles of recruitment and gas exchange is introduced. The combined model has the ability to estimate cardiac output (CO) changes with respect to PEEP changes during MV therapy. In addition, the model relates the coupled areas of circulation and pulmonary management, as well as linking these MV decision support models to oxygenation based clinical endpoints. A proof of concept is shown for this model by combining two different retrospective datasets and highlighting its ability to capture clinically expected drops in CO as PEEP increases. The model allows valuable cardiovascular circulation data to be predicted and also provides an alternative method and clinical end point by which PEEP could be optimised. The model requires further clinical validation before clinical use, but shows significant promise. The models developed and tested in this research enable rapid parameter identification from minimal, readily available clinical data, and thus provide a novel way of guiding therapy. The models can potentially provide clinicians with information to select an optimal patient-specific level of PEEP using only standard ventilation data, such as pressure-volume curves. In addition, the development of a dFRC stress model provides a unique population constant, β. Overall, the modelling approaches developed and validated in this research provide several novel methods of guiding therapy setting mechanical ventilation parameters and tracking and assess a patient’s lung condition. This research thus creates and provides novel validated methods for improving MV therapy with minimal cost or added invasiveness.

The purpose of this study was to explore and describe nurse-patient communication during critical illness events. The theoretical structure of the study was drawn from communication, sociolinguistic, and nursing theory. Data were collected in a 374-bed private hospital in the Southwest. The sample consisted of six registered nurses and nine patients experiencing cardiac surgery. Nine observed and audiotaped nurse-patient interactions, and fourteen audiotaped partcipant interviews provided the data base for analysis. Content analysis was used to organize the data. Findings were presented in terms of language, paralanguage, and nonverbal expression, and in terms of content, process, and product of nurse-patient communication. Participants used biomedical-technical language and casual-everyday language during the interactions. Nurses talked about what patients would experience while patients talked about themselves as a way of establishing their credibility within the biomedical setting. Nurses viewed nurse-patient communication as variable depending on the patients' needs and responses. Patients viewed nurse-patient communication as straightforward, not requiring adjustment for the needs of the participants. Products of communication for patients involved increased knowledge, reassurance, and increased confidence. Products of communication for nurses involved relieving the patients' anxieties, considering the patients' remembering, and increasing the nursing staff's knowledge about the patient while helping the patient to know the goals of the nursing staff. The introduction and closure segments of the six nurse-patient interactions for preoperative preparation of the patient were analyzed. Nurses began the introductions by assuming that the patients needed relief from anxiety but the patients demonstrated politeness more than anxiety. Nurses used strategies of questioning, starting the physical assessment, topic persistence, and self-monitoring to control the closure segments. Patients used narratives and humor as control strategies. The study findings suggest conceptual areas relevant to nurse-patient communication which may ground theoretical model development for nurse-patient communication. Nurses in clinical settings can compare their patient communication experiences with the findings of the study in order to increase their understanding of expression, form, and function of nurse-patient communication.

The purpose of this study was to describe maternal coping effort. The sample was composed of 30 mothers of infants hospitalized in the neonatal intensive care unit. Descriptive and correlational statistics were used to determine maternal coping effort and the maternal factors that may be associated with coping effort. Results of the study showed that a majority of the mothers exerted a great amount of effort to cope with situations encountered in the NICU. Maternal age, marital status, gravidity and parity, mode of delivery and ethnicity did not prove to associate significantly with coping effort. The results of this study are significant to nursing practice in the confirmation of the high degree of maternal coping associated with the hospitalization of an infant in the NICU.

En svårt sjuk patient som vårdas på en intensivvårdsavdelning, med svikt i ett eller flera organsystem, löper betydande risk att drabbas av malnutrition med ökad risk för infektioner och längre vårdtider. När en väl utarbetad riktlinje inom nutrition följs ökar patientens möjligheter att nå upp till sitt kalorimål med minskad malnutrition och förkortade vårdtider som följd. Syftet med studien var att undersöka följsamheten till en befintlig riktlinje om nutrition på en intensivvårdsavdelning i västra Sverige med hjälp av journalgranskning. Ett konsekutivt urval gjordes och 31 uppfyllde inklusionskriterierna. Journalerna granskades enligt deskriptiv analys. Resultatet visade en varierande följsamhet till riktlinjen med högst följsamhet mot slutet av vårdtiden och lägst följsamhet i början av vårdtiden. Med hjälp av resultatet i denna studie kan följsamheten till riktlinjen förbättras och på så sätt kan bedömning och behandling av nutrition för intensivvårdspatienten optimeras. / A critically ill patient within the intensive care unit, with failure in one or more organ systems, has an increased risk of malnutrition with infections and extended hospital stay as a result. When a wellestablished guideline of nutrition is used, the patients possibility of reaching the caloric goal increases which lead to decreased malnutrition and shortened hospital stay. The aim of the study was to investigate the compliance of an enteral and parenteral guideline in an intensive care unit in a hospital in the west of Sweden with a review of medical records. A consecutive sample was made and 31 patients met the criteria. The medical records were reviewed according to descriptive analysis. The results showed a varying compliance to the guideline, with the highest compliance in the end of hospital stay and the lowest compliance in the beginning of hospital stay. Using the results in this study, the compliance of the nutritional guideline can be improved, and nutritional assessment and treatment for the intensive care patient can be optimized.

Thermoregulation is considered a top priority in neonatology due to the fact that relative to adults, neonates have a morphological susceptibility to excessive heat exchange with the environment, and exhibit limited physiological/behavioural responses to thermal strain. Consequently, the environmental conditions in which they are nursed must be tightly regulated to maintain body temperature stable. Neonatal intensive care units (NICU) use radiant warmers (RW) to thermally manage many newborns. However, recent evidence suggests that RW induce intermittent bouts of thermal strain that could adversely affect patients. This warrants further investigation of neonatal heat balance and the pertinent factors affecting it. Conducting an exhaustive audit of heat exchanges affecting the body during standard care under a RW could yield important information that would lead to the improvement of clinical practice in NICUs. The present thesis focuses on neonatal thermoregulatory responses, various body heat exchange mechanisms and processes during standard care under RW.

The needs of patients who are nursed on the ICU are becoming more widely recognised and services are beginning to reflect this. However there is little research into how patients who have suffered from a severe and progressive muscular paralysis called Guillain-Barré Syndrome (GBS) experience the disease and subsequent hospitalisation. The purpose of this study was to explore how these patients experience the different aspects of the illness, including an extended period of paralysis and treatment on an ICU. This is intended to expand upon the limited research in this area and identify how the findings can inform clinical practice and future studies. Method: A systematic literature search identified research in relation to the experiences of individuals who had GBS which was utilised to form the basis of the understanding for this study. Very little systematic research has looked at individuals‟ experiences of Guillain-Barré Syndrome whilst ill and their subsequent recovery. A mixed methods study was carried out with the aim of adding to this research. Interpretative Phenomenological Analysis was selected as the method of analysis for Study 1, which involved interviews with seven participants who had experienced GBS severe enough to need treatment on an ICU. This then enabled quantitative questionnaires to be disseminated which asked about individuals‟ levels of anxiety, depression and Post Traumatic Stress symptomatology both retrospectively and following recovery in Study 2. Results: Study1 found that participants experienced GBS as either a slow and frustrating, or as a rapid and scary onset. The main themes that were developed included: the paralysis being viewed as multiple losses, frustration, difficulties associated with communication loss, vulnerability and frightening hallucinations. Study 2 utilised non-parametric analyses of the data and found that participants experienced high levels of anxiety and depression at the onset of GBS and that some continued to experience anxiety, depression and post traumatic symptoms after recovery from GBS. Generally the profile suggests predominantly anxiety problems during the acute onset phase and then predominantly depression at the time of follow-up. Aspects of post traumatic stress were positively correlated with duration of mechanical ventilation which in turn was related to duration of paralysis. This challenged the hypothesis that GBS patients habituate to the experience of paralysis. Conclusion: For some individuals, GBS was experienced as a frightening event, but one that they could draw positive things from. However, for others, GBS was experienced as a traumatic event and some of these people continued to exhibit signs of psychological distress even after recovery. It remains important for staff to feel able to speak about distressing situations with their patients and to signpost them to other psychological services if appropriate.

This thesis focuses on the explanation of anomalies as an approach to anomaly-driven revision of a theory. An anomaly is identified when a theory (or model of a domain) does not accurately reflect a domain observation, indicating that the theory (or model) requires refinement. In some cases an explanation can be generated for an anomalous observation using existing domain knowledge and hence a revision to the existing theory can be provided. Ontologies have been used in both stages of an investigation presented in this thesis; in the first stage, a domain ontology and expert-acquired strategies have been used as part of a knowledge-based system, EIRA (Explaining, Inferencing, and Reasoning about Anomalies), to generate explanations for an anomaly; in the second stage, domain ontologies have been used to suggest refinements to an incorrect or incomplete domain ontology. In the first stage of the investigation, extensive interviews were held with domain experts; the analysis of which led to the identification of both examples of anomalies encountered in the domain and the strategies used by the domain experts to provide (appropriate) explanations for the anomalies. EIRA is able to replicate these explanations; when EIRA is presented with an anomaly, potential explanations are generated by the application of expert-acquired strategies to the domain knowledge, patient data, and information about the clinical situation. To evaluate this approach, EIRA has been applied in the Intensive Care Unit (ICU) domain and ICU clinicians have evaluated the explanations produced by EIRA. The strategies used by EIRA have been abstracted further to form generic strategies for anomaly resolution. In the second stage, EIRA has been extended to investigate the use of domain ontologies to suggest refinements to an incomplete or incorrect ontology. These additional refinements are generated by reasoning about analogous concepts from the domain ontology. The findings described in this thesis support the belief that ontologies can be used to generate explanations to refine a theory, further, that the extensive domain knowledge contained in an ontology allows for sophisticated refinements of a knowledge base. Previous approaches to theory revision have largely focused on the refinement of an instantiated rule base, in which limited domain knowledge is incorporated in the rules and hence the refinements are essentially captured in a particular knowledge base. In these earlier approaches, refinements to remove the anomaly were generally suggested after applying machine learning techniques on data from the domain; however, this process requires large datasets, the refinements generated are not always acceptable to domain experts, and providing explanations (using an ontology) to account for anomalies have not been investigated. I believe that the findings reported in this thesis are significant and make a number of contributions including a novel approach to anomaly-driven revision of a theory.

Class of 2012 Abstract / Specific Aims: The objective of this study is to evaluate and compare clinical outcomes and economic impact involved with the use of beractant (B) compared to poractant (P) for the treatment of respiratory distress syndrome (RDS) in premature neonates admitted to a neonatal intensive care unit. Methods: Patients were included if they were less than 35 weeks gestational age at birth, survived at least 48 hours, and admitted to the neonatal intensive care unit and treated with P or B for RDS. The primary outcome of this study is the change in the fraction of inspired oxygen (FiO2) over the first 48 hours after surfactant administration. Secondary outcomes were the change in oxygen saturation, time spent on mechanical ventilation and continuous positive airway pressure (CPAP), complication occurrence and mortality of the neonates. Main Results: There were a total of 40 neonates whose charts were reviewed (n= 13 and n=27 in the P and B groups respectively). The mean gestational age of the neonates were 29.2+/-2.9 and 28.8+/-2.9 weeks in the P and B groups respectively. The FiO2 was found to not be lower between the P and B groups (35.5+/-22.2 and 42.4+/-24.2, respectively; p=0.379), as well as the O2 saturation (94.6+/-4.6 and 92.3+/-6.1; p=0.194). Significance was also not found for the other clinical or economic outcomes assessed in this study. Conclusions: There was not a significant difference between poractant and beractant in FiO2, O2 saturation, or in the other clinical outcomes evaluated in this study.

Background: Nowadays people more often are surviving intensive care, which makes it important to increase the knowledge about the experiences. Illusions, nightmares and unreal experiences are common and often linger for quite some time. Aim: The aim of the study was to illuminate patients' experiences after intensive care. Method: A literature-based study of 16 qualitative studies was conducted Results: A lot of the patients have difficulties moving on, and are haunted by their experience. Memories from the hospital stay are often hazy, and evokes a sense of lacking a part of their life story. There is a need to understand in order to move on. Despite of this, some of the patients manage to find happiness. They find a new meaning in life, and learn to look at things from a brighter side. Conclusion: To process the experience, there seems to be a need of further support. Also, patients need to receive more information about what to expect after discharge.