Thesis advisor: Dorothy A. Jones / Thesis advisor: Pamela J. Grace / The purpose of the study was to explore the relationship between multiple variables within a model of critical thinking and moral reasoning that support and refine the elements that significantly correlate with accuracy and clinical decision-making. <bold>Background:</bold> Research to date has identified multiple factors that are integral to clinical decision-making. The interplay among suggested elements within the decision making process particular to the nurse, the patient, and the environment remain unknown. Determining the clinical usefulness and predictive capacity of an integrated ethically driven environmental model of decision making (IEDEM-CD) in emergency settings in facilitating accuracy in problem identification is critical to initial interventions and safe, cost effective, quality patient care outcomes. Extending the literature of accuracy and clinical decision making can inform utilization, determination of staffing ratios, and the development of evidence driven care models. <bold>Methodology:</bold> The study used a quantitative descriptive correlational design to examine the relationships between multiple variables within the IEDEM-CD model. A purposive sample of emergency nurses was recruited to participate in the study resulting in a sample size of 200, calculated to yield a power of 0.80, significance of .05, and a moderate effect size. The dependent variable, accuracy in clinical decision-making, was measured by scores on clinical vignettes. The independent variables of moral reasoning, perceived environment of care, age, gender, certification in emergency nursing, educational level, and years of experience in emergency nursing, were measures by the Defining Issues Test, version 2, the Revised Professional Practice Environment scale, and a demographic survey. These instruments were identified to test and refine the elements within the IEDEM-CD model. Data collection occurred via internet survey over a one month period. Rest's Defining Issues Test, version 2 (DIT-2), the Revised Professional Practice Environment tool (RPPE), clinical vignettes as well as a demographic survey were made available as an internet survey package using Qualtrics TM. Data from each participant was scored and entered into a PASW database. The analysis plan included bivariate correlation analysis using Pearson's product-moment correlation coefficients followed by chi square and multiple linear regression analysis. <bold>Findings: </bold>The elements as identified in the IEDEM-CD model supported moral reasoning and environment of care as factors significantly affecting accuracy in decision-making. Findings reported that in complex clinical situations, higher levels of moral reasoning significantly affected accuracy in problem identification. Attributes of the environment of care including teamwork, communication about patients, and control over practice also significantly affected nurses' critical cue recognition and selection of appropriate interventions. Study results supported the conceptualization of the IEDEM-CD model and its usefulness as a framework for predicting clinical decision making accuracy for emergency nurses in practice, with further implications in education, research and policy / Thesis (PhD) — Boston College, 2011. / Submitted to: Boston College. Connell School of Nursing. / Discipline: Nursing.

Evidence based medicine (EBM) is defined as the use of best available evidence for decision making, and it has been the predominant paradigm in clinical decision making for the last 20 years. EBM requires evidence from multiple sources to be combined, as published results may not be directly applicable to individual patients. For example, randomised controlled trials (RCT) often exclude patients with comorbidities, so a clinician has to combine the results of the RCT with evidence about comorbidities using his clinical knowledge of how disease, treatment and comorbidities interact with each other. Bayesian networks (BN) are well suited for assisting clinicians making evidence-based decisions as they can combine knowledge, data and other sources of evidence. The graphical structure of BN is suitable for representing knowledge about the mechanisms linking diseases, treatments and comorbidities and the strength of relations in this structure can be learned from data and published results. However, there is still a lack of techniques that systematically use knowledge, data and published results together to build BNs. This thesis advances techniques for using knowledge, data and published results to develop and refine BNs for assisting clinical decision-making. In particular, the thesis presents four novel contributions. First, it proposes a method of combining knowledge and data to build BNs that reason in a way that is consistent with knowledge and data by allowing the BN model to include variables that cannot be measured directly. Second, it proposes techniques to build BNs that provide decision support by combining the evidence from meta-analysis of published studies with clinical knowledge and data. Third, it presents an evidence framework that supplements clinical BNs by representing the description and source of medical evidence supporting each element of a BN. Fourth, it proposes a knowledge engineering method for abstracting a BN structure by showing how each abstraction operation changes knowledge encoded in the structure. These novel techniques are illustrated by a clinical case-study in trauma-care. The aim of the case-study is to provide decision support in treatment of mangled extremities by using clinical expertise, data and published evidence about the subject. The case study is done in collaboration with the trauma unit of the Royal London Hospital.

Introdução: Descontinuação prematura ou tardia da ventilação mecânica invasiva (VM) associa-se a maior morbimortalidade. Redução da pressão intratorácica durante o teste de respiração espontânea (TRE) pode precipitar disfunção cardíaca através da elevação abrupta do retorno venoso e da pós-carga do ventrículo esquerdo. Da mesma maneira, alterações na demanda respiratória e cardíaca que ocorrem ao longo do TRE também podem manifestar-se à ultrassonografia pulmonar. O padrão B é um artefato sonográfico que se correlacionada com edema intersticial. Um ensaio clínico randomizando concluiu que a ultrassonografia pulmonar foi capaz de prever insuficiência ventilatória pós extubação através de variações na aeração pulmonar observadas durante o procedimento de desmame; contudo, a ferramenta não pôde rastrear pacientes antes da submissão ao TRE. O impacto do balanço hídrico (BH) e de sinais radiológicos de congestão pulmonar antes do TRE sobre os desfechos no desmame também precisam ser determinados. Métodos: Cinquenta e sete indivíduos elegíveis para o desmame ventilatório foram recrutados. Traqueostomizados foram excluídos. Realizou-se avaliação ultrassonográfica de seis zonas pulmonares imediatamente antes e ao final do TRE. Predominância B foi definida como qualquer perfil com padrão B presente bilateralmente em região torácica anterior. Os pacientes foram seguidos por até 48 horas depois da extubação. Após esse estudo piloto, foi conduzido um estudo observacional, prospectivo, multicêntrico em duas unidades de terapia intensiva (UTIs) clínico-cirúrgicas ao longo de dois anos. Os mesmos critérios de inclusão e de exclusão foram aplicados; contudo, a ultrassonografia foi realizada apenas antes do TRE. O desfecho primário foi falha no TRE, definido como incapacidade de tolerar o teste T durante 30 a 120 minutos e, nesse caso, o paciente não era extubado. Dados demográficos e fisiológicos, BH das 48 horas antecedendo o TRE (entrada de fluidos menos débitos durante 48 horas) e desfechos foram coletados. Em uma análise post hoc de 170 procedimentos de desmame, um radiologista aplicou um escore radiológico na interpretação de radiografias digitais de tórax realizadas previamente ao TRE – o exame mais recente disponível foi avaliado em termos de congestão pulmonar. Resultados: No estudo piloto, 38 indivíduos foram extubados com sucesso, 11 falharam no TRE e 8 necessitaram de reintubação em até 48 horas após a extubação. No início do teste T, padrão B ou consolidação já estava presente em porções inferiores e posteriores dos pulmões em mais da metade dos casos, e tais regiões mantiveram-se não aeradas até o final do teste. Perda de aeração pulmonar durante o TRE foi observada apenas no grupo que falhou no mesmo (p= 0,07). Esses pacientes também demonstraram maior predominância B ao final do teste (p= 0,019). Antes do procedimento de desmame, todavia, não foi possível discernir indivíduos que falhariam no TRE, tampouco aqueles que necessitariam de reintubação dentro de 48 horas. Posteriormente, de 2011 a 2013, 250 procedimentos de desmame foram avaliados. Falha no TRE ocorreu em 51 (20,4%). Cento e oitenta e nove pacientes (75,6%) foram extubados na primeira tentativa. Indivíduos que falharam no TRE eram mais jovens (mediana de 66 versus 75 anos, p= 0,03) e apresentaram maior duração de VM e maior prevalência de doença pulmonar obstrutiva crônica (DPOC) (19,6 versus 9,5%, p= 0,04). Predominância B mostrou-se um preditor muito fraco para falha no TRE, exibindo sensibilidade de 47%, especificidade de 64%, valor preditivo positivo de 25% e valor preditivo negativo de 82%. Não houve diferença estatisticamente significativa no BH das 48 horas antecedendo o TRE entre os grupos (falha no TRE: 1201,65 ± 2801,68 ml versus sucesso no TRE: 1324,39 ± 2915,95 ml). Entretanto, em pacientes portadores de DPOC, ocorreu associação estatisticamente significativa entre BH positivo nas 48 horas antes do TRE e falha no TRE (odds ratio= 1,77 [1,24 – 2.53], p= 0,04). O escore radiológico, obtido em 170 testes T, foi similar entre os pacientes com falha e sucesso no TRE (mediana de 3 [2 – 4] versus 3 [2 – 4]), p= 0, 15). Conclusão: Maior perda de aeração pulmonar observada à ultrassonografia durante o TRE pode sugerir disfunção cardiovascular e aumento na água extravascular, ambos induzidos pelo processo de desmame. BH, sinais radiológicos de congestão pulmonar ou padrão B documentado através de um protocolo ultrassonográfico simplificado não devem contraindicar o TRE em pacientes estáveis hemodinamicamente e adequadamente oxigenados, haja vista o fato de tais variáveis não terem predito maior probabilidade de falha de desmame em pacientes críticos clínico-cirúrgicos. Ainda assim, evitar BH positivo em pacientes com DPOC parece otimizar os desfechos do desmame. / Introduction: Both delayed and premature liberation from mechanical ventilation (MV) are associated with increased morbi-mortality. Inspiratory fall in intra-thoracic pressure during spontaneous breathing trial (SBT) may precipitate cardiac dysfunction through abrupt increase in venous return and in left ventricular afterload. Changes in respiratory and cardiac load occurring throughout SBT might manifest with dynamic changes in lung ultrasound (LUS). B-pattern is an artifact that correlates with interstitial edema. A randomized controlled trial concluded that bedside LUS could predict post extubation distress due to changes in lung aeration throughout weaning procedure; however, it could not screen patients before submission to SBT. The impact of fluid balance (FB) as well as of radiological signs of pulmonary congestion prior to SBT on weaning outcomes must also be determined. Methods: Fifty-seven subjects eligible for ventilation liberation were enrolled. Patients with tracheostomy were excluded. LUS assessment of six thoracic zones was performed immediately before and at the end of SBT. B-predominance was defined as any profile with anterior bilateral B-pattern. Patients were followed up to 48 hours after extubation. After this pilot report, we conducted a 2-year prospective, multicenter, observational study in two adult medical surgical intensive care units (ICUs). Same inclusion and exclusion criteria were applied; however, LUS was performed only immediately before SBT. The primary outcome was SBT failure, defined as inability to tolerate a T-piece trial during 30 to 120 minutes, in which case patients were not extubated. Demographic, physiologic, FB in the preceding 48 hours of SBT (fluid input minus output over the 48-hour period), and outcomes data were collected. As a post hoc analysis in 170 weaning procedures performed in one of the ICUs, an attending radiologist applied a radiological score on interpretation of digital chest x-rays performed before SBT - the most recent available exam was analyzed regarding degree of lung fluid content. Results: In the pilot study, 38 subjects were successfully extubated, 11 failed the SBT and 8 needed reintubation within 48 hours of extubation. At the beginning of T-piece trial, B-pattern or consolidation were already found at lower and posterior lung regions in more than half of the individuals and remained nonaerated at the end of the trial. Loss of lung aeration during SBT was observed only in SBT-failure group (p= 0.07). These subjects also exhibited higher B-predominance at the end of trial (p= 0.019). Prior to weaning procedure, however, we were not capable to discriminate individuals who would fail SBT, nor who would need reintubation within 48 hours. Afterwards, from 2011 to 2013, 250 weaning procedures were evaluated. SBT failure occurred in 51 (20.4%). One hundred eighty-nine patients (75.6%) were extubated at first attempt. Individuals who failed SBT were younger (median 66 versus 75 years, p= 0.03), had higher duration of MV (median 7 versus 4 days, p< 0.0001) and higher prevalence of chronic obstructive pulmonary disease (COPD) (19.6 versus 9.5%, p= 0.04). B-predominance was a very weak predictor for SBT failure, showing 47% sensitivity, 64% specificity, 25% positive predictive value, and 82% negative predictive value. There were no statistically significant differences in 48 hour-FB prior to SBT between groups (SBT failure: 1201.65 ± 2801.68 mL versus SBT success: 1324.39 ± 2915.95 mL). However, in COPD subgroup, we found significant association between positive FB in the 48 hours prior to SBT and SBT failure (odds ratio = 1.77 [1.24 – 2.53], p= 0.04). Radiological score, obtained in 170 T-piece trials, was similar between SBT failure and success subjects (median 3 [2 - 4] vs 3 [2 - 4], p= 0.15). Conclusion: Higher loss of lung aeration observed by LUS during SBT might suggest cardiovascular dysfunction and increases in extravascular lung water, both induced by weaning. Neither FB, nor radiological findings of pulmonary congestion, nor B-pattern detected by a simplified LUS protocol should preclude hemodynamically stable, sufficiently oxygenated patients from performing an SBT, since such variables did not predict greater probability of weaning failure in medical-surgical critically ill population. Notwithstanding, avoiding positive FB in COPD patients might improve weaning outcomes.

Although clinical reasoning is both broad and complex, the term “clinical reasoning” is contested and multiple definitions have been mooted within different contexts. In its simplest form, clinical reasoning is regarded as a “decision-making” process. Other definitions outline it in terms of a complex cognitive process, posited within multiple contextual factors. Traditionally, clinical reasoning models have been based upon cognitive theories. More recently, interpretive theories have been applied. Despite extensive research over the past four decades, no consensus on how clinical reasoning actually occurs has been achieved. Accurate clinical reasoning is vital to patient safety. Its importance as an essential clinical competence for healthcare professionals is well established. Indeed, it is the crux of a clinician’s work. Frequently, Foundation doctors are the first to review acutely unwell patients. During out-of-hours shifts senior help can be scant and Foundation doctors may have to rely on their own initial clinical reasoning to manage acutely unwell patients. This PhD explores clinical reasoning development in the transition phase between final year medical student and Foundation doctor (5MB-FY1 transition) in relation to acutely unwell patients. It follows a cohort of final year medical students from a single UK university on their clinical reasoning journeys as they transition into Foundation doctors, focusing on the role of the simulated healthcare setting and the workplace. The principle research question for this PhD was how does clinical reasoning develop across the transition phase between final year of medical school and Foundation year one? Within this overarching research question, the following sub-questions were posed: What do participants understand by the term clinical reasoning? What types of clinical reasoning experiences do participants narrate? How do participants clinically reason for acutely unwell patients? Which factors do participants perceive as being facilitating and hindering to their clinical reasoning? How do participants’ clinical reasoning processes develop across the 5MB-FY1 transition phase? This PhD uses multiple methodologies derived from interpretive approaches in innovative ways to tap into clinical reasoning processes and its development across four data collection points: T1: group and individual interviews; T2: Ward Simulation Exercise observations and stimulated recall interviews; T3: workplace observations and stimulated recall interviews; T4: final interviews. Data were collected from T1/T2 and T3/T4 during the final year of medical school and Foundation year one respectively. Primary thematic analyses were carried out cross-sectionally and longitudinally in terms of what participants said and how they said it. Secondary narrative analyses were undertaken of participants’ Personal Incident Narratives. By taking an interpretive approach, the complexities of clinical reasoning processes, both in terms of internal cognition and external socio-cultural influences were illuminated, drawing upon clinical reasoning, complexity and situated learning theories. The key findings of this PhD were that participants conceptualised clinical reasoning as a “decision-making” and “thinking” process, leading to a clinical judgement for patient care; participants narratives aided understanding of clinical reasoning process and factors which facilitated and hindered them; participants used experiential knowledge and protocols to clinically reason for diagnosis, investigation, management and prioritisation; participants retained flexibility and contextual variability in the processes of making their clinical judgements; multiple factors facilitated and hindered the equilibrium of clinical judgement processes; and clinical reasoning development is dependent upon a complex interplay of individual, interpersonal and systemic factors which are deeply embedded in social-cultural theory. This study has multiple strengths and original features such the high participant retention rate throughout the longitudinal study, the exploration of the 5MB-FY1 transition, contemporaneous observations of clinical interactions with patients, the exploration of the out-of-hour setting contemporaneously and the multiple methods of data collection used in innovative ways. This PhD develops the published literature further in these domains. However, its challenges were predominantly ethical, such as lack of patient capacity to consent in the workplace.

This session is developed by, and presenters invited by Speech Sound Disorders in Children. A case-based approach will be used to assess the complexity of SSD through assessment and analysis measures that guide clinical decisions regarding differential diagnosis, intervention planning, and progress monitoring.

Stroke is the fifth leading cause of death in the U.S. with approximately 795,000 Americans experiencing a stroke each year. In addition to common difficulties with communication and physical impairments following stroke, psychosocial impacts warrant assessment and treatment. Experiencing a stroke can lead to depression, mood disorders, and difficulties with emotion regulation. It is well documented that post-stroke depression (PSD) affects a third of stroke survivors. Higher levels of depression and depressive symptoms are associated with a less efficient use of rehabilitation services, poor functional outcomes, greater odds of hospital readmission, negative impacts on social participation, and increased mortality. The acute phase of stroke recovery may be a key factor in influencing the depression trajectory with early depression predicting poor longitudinal outcomes. The current approach to treating PSD is medication. However, psychotherapy approaches have demonstrated more promise in preventing PSD. Investigations into music-based treatments have shown encouraging results following acquired brain injuries with active music therapy interventions demonstrating large effect sizes for mood improvement. Therefore, the purpose of this three-part dissertation was to examine the effects of active music therapy on mood and describe the clinical decision making process of using music therapy to target mood elevation for hospitalized adults following a first-time acute ischemic stroke. The first study examined the effect of one treatment of active music therapy on mood following a first-time ischemic stroke during acute hospitalization. Active music therapy was defined as music making interventions that elicit and encourage active participation from participants. The Faces Scale was used to assess mood immediately prior to and following treatment. Forty-four adults received at least one treatment. A significant change in mood was found following one treatment. Comment analysis indicated that participants viewed music therapy as a positive experience. The second study investigated the impact of receiving two treatments of active music therapy on mood as compared to one. No significant difference was found between those who received one treatment and those who received two. Both dosing groups demonstrated significant mood improvement; however Group 2 (two treatments) had more severe strokes and did not improve until the second session. The purpose of the third study was to describe the clinical decision-making (CDM) process of a music therapist targeting mood elevation for hospitalized patients following a first-time acute ischemic stroke. The Three Phase Process Model of Collaborative Self-Study was selected as a guiding qualitative methodological framework. Data was collected from four sources: (a) electronic medical records, (b) audio recordings of eight music therapy treatments, (c) a researcher journal, and (d) patient and caregiver/visitor comments. Results indicate that factors influencing CDM included progression through a four-stage treatment process, use of a variety of music-based and therapy-based techniques, and the monitoring and influencing of participant levels of arousal, affect, salience, and engagement. In conclusion, active music therapy during acute hospitalization following a first-time ischemic stroke is effective in significantly improving mood. Components of clinical decision making to elevate mood are illustrated in a provided conceptual framework. Continued investigation is warranted with consideration of stroke severity, dosing amounts, and additional outcomes of interest. Longitudinal investigation is needed to evaluate the impact of treatment on the trajectory of post-stroke depression.

In the United States nearly 1 million annual new and recurrent myocardial infarctions (MI) occur with 10% of patients hospitalized with MI having unrecognized ischemic symptoms. Inexperienced nurses are expected to accurately interpret cardiac symptom cues, possibly without ever having experienced care of patients with MI, yet have been shown to be less able to classify symptom cues and reach accurate conclusions than experienced nurses. The purpose of this study was to test an educational intervention using theories of pattern recognition to develop CT in MI and improve nursing students’ clinical decision-making and clinical judgment using high fidelity patient simulation. This study used a quasi-experimental three group pre-/post-test design and qualitative data to triangulate information on critical thinking, clinical decision-making, and clinical judgment in MI. A sample of junior baccalaureate in nursing students (N = 54) from a large metropolitan university were divided in pairs and randomized to one of two control groups. Data were collected with instruments which measured pattern recognition in MI, critical thinking in MI, and self-perception of clinical decision-making. In addition, diagnostic efficiency and accuracy were measured. Triangulation on clinical decision making with semi-structured interviews using ‘thinking aloud’ technique was conducted. Data were analyzed as qualitative data and compared among groups. Students who were given prototypes for MI using simulation significantly improved critical thinking as measured by pattern recognition in MI (t(3.153(2), p = .038) compared with the non-simulation control group. Qualitative findings showed that students receiving the experimental simulation with a non-MI scenario and feedback-based debriefing had greatest gains in clinical reasoning which included development of clinical decision-making using analytic hypothetico-deductive and Bayesian reasoning processes and learned avoidance of heuristics. Students receiving the experimental simulation learned to identify salient symptom cues, analyzed data more complexly, and reflected on their simulation experience in a way which students reported improved learning. Students who were given MI only simulation scenarios developed deleterious heuristics and showed fewer gains in clinical reasoning, though both simulation groups demonstrated greater critical thinking ability than the non-simulation control group. Findings support the use of simulation to improve clinical reasoning including pattern recognition and clinical decision-making, and emphasize the significance of simulation scenario construction and debriefing to achieving learning outcomes. The findings could be used to guide further research to improve critical thinking, clinical decision-making, and clinical judgment in nursing students using simulation. Funding for this study was provided by the American Association of Critical Care Nurses and Philips Medical Systems and a testing grant from Elsevier, Assessment.

Abstract Both qualitative and quantitative limitations of two-dimensional (2DE) imaging have lead to the emergence of the three-dimensional echo (3DE) technique. Until recently the development of 3DE technology has been slow due to inferior image quality and longer processing and acquisition times compared with 2DE. However, in recent times 3DE technology has advanced to “real-time” (RT3D) and has become feasible as a standard clinical tool. The overall hypothesis of the studies undertaken in this thesis is that the increased accuracy of left ventricular (LV) assessment using RT3D justifies its use in clinical decision-making based on both single and sequential measurements in routine echocardiographic practice. It shows the increased accuracy and feasibility of 3DE using online and offline techniques and opacification, and evaluates the prognostic implications of LV measurements globally and regionally using 3DE compared with 2DE. Further, it assesses the accuracy of LV assessment using 3DE and demonstrates its superior accuracy to 2DE in cross-sectional studies. The thesis initially reviews the use of physiologic parameters used for clinical decision making and looks at the principles of incremental value in diagnostic testing. The assessment of ventricular structure and function is discussed as well as the current problems with clinical echocardiography, which have lead to the evolution and development of 3DE. The second chapter describes the methodologies used in this thesis, with particular emphasis on new technologies used in the studies. Chapter 3 looks at the role of experience as a barrier to incorporation of 3DE into standard practice. We tested attendees before and after an intensive interactive training course to evaluate the learning curve. An interactive teaching course with rehearsal and direct mentoring appears to overcome this limitation and may improve the uptake of the 3DE technique. Chapters 4 to 6 validate the use of 3DE by comparing it to 2DE and magnetic resonance imaging (MRI) with respect to online and offline techniques, the use of left ventricular opacification (LVO) and the serial follow-up of patients. The availability of automated on-line software may increase the feasibility of real-time 3DE for LV volume calculation in clinical practice. Chapter 4 looks at the comparison of off- and on-line approaches with magnetic resonance imaging. Online measurement of LV volumes was found to be feasible and more accurate than with 2DE, however the offline approach was more accurate - although more time-consuming. Chapter 5 involves two studies which sought to validate 3DE in a multicentre setting. They examine the variability of LV measurements across multiple sites and to validate 3DE against MRI. The first study found that the semi-automated measurement of 3DE reduces the variation of LV volume between centers. The second study provides information on the role of different potential sources of error and provides guidelines for future users on how to minimize these errors as well as how to interpret their findings. The next chapter further validates 3DE with use of LVO as a technique to improve the accuracy of LV volume measurements. We sought to examine the accuracy of non-contrast and contrast enhanced 2DE and 3DE for calculation of LV volumes and ejection fraction (EF), relative to cardiac magnetic resonance imaging. 2DE with LVO was analogous to 3DE in accurate categorization of LV function. However, 3DE with LVO was feasible and superior to other non-contrast and contrast enhanced techniques in patients with previous infarction. Chapter 7 examines the technical details of regional volume measurements. The use of a fixed external frame of reference in analyses of regional wall motion in the apical four-chamber view is prone to a systematic error and the use of a floating-axis analysis corrects for this, but this is based on landmarks by MRI (apex, annulus) and center of mass by 3DE. The axis is likely to be influenced by reverse remodeling after intervention and therefore we sought to evaluate 3DE regional volume assessment vs. cardiac MRI over follow-up. The use of a center-line based on center of mass with RT3D may contribute to problems with use of this modality to track regional volumes over time. Although global 3DE volumes compare well with MRI volumes, new developments in image quality and automated software will be needed before changes in regional volumes can be reliably followed with 3DE. 2DE ESE is limited by sampling in standard imaging planes and suboptimal acquisition may cause poor matching of pre- and post-stress images. 3DE may avoid these orientation problems and contraction front mapping (CFM) may also provide a method for defining the temporal homogeneity of contraction. Chapter 8 examines the incremental benefit of 3DE CFM to 2DE and 3DE, using coronary angiography as the reference standard. It found that analysis of the temporal distribution of contraction may be an alternate means than 3DE wall motion assessment for identification of ischemia for ESE. Another significant validation needed for 3DE is not only for the LV but for the right ventricle (RV). The non-geometric nature of the RV makes it difficult to measure. Chapter 9 shows that 3DE is superior to 2DE for follow-up of RV function by validation vs. cardiac MRI. It was found that 3DE was indeed more accurate than 2DE approaches and reduces test-retest variation of RV volumes and EF measurements in follow-up RV assessment. Chapter 10 investigates the accuracy and reproducibility of the use of 3DE for serial follow-up of LV measurements. Echocardiographic follow-up of LV volumes is difficult because of the test-retest variation of 2DE. In this follow-up study, sequential 3DE measurements of change of volumes and EF were similar to those obtained using MRI, but 2DE overestimated change in EDV. As MRI is expensive, of limited availability and cannot be performed on patients with implanted devices, 3DE appears to be an effective long-term follow-up imaging tool for when sequential measurement of LV volumes is sought to guide management decisions. Chapter 11 investigates whether 3DE is more predictive of outcome than 2DE. In this outcome study, 3DE measurements of ESV and EF showed a stronger prediction of outcomes than 2DE. 3DE now appears to be the measurement of choice for when LV volumes and EF are sought to guide management decisions. In conclusion, the work reported in this thesis demonstrates that 3DE increases the accuracy of LV assessment and justifies its use in clinical decision-making based on both single and sequential measurements in routine echocardiographic practice.

Introdução: Descontinuação prematura ou tardia da ventilação mecânica invasiva (VM) associa-se a maior morbimortalidade. Redução da pressão intratorácica durante o teste de respiração espontânea (TRE) pode precipitar disfunção cardíaca através da elevação abrupta do retorno venoso e da pós-carga do ventrículo esquerdo. Da mesma maneira, alterações na demanda respiratória e cardíaca que ocorrem ao longo do TRE também podem manifestar-se à ultrassonografia pulmonar. O padrão B é um artefato sonográfico que se correlacionada com edema intersticial. Um ensaio clínico randomizando concluiu que a ultrassonografia pulmonar foi capaz de prever insuficiência ventilatória pós extubação através de variações na aeração pulmonar observadas durante o procedimento de desmame; contudo, a ferramenta não pôde rastrear pacientes antes da submissão ao TRE. O impacto do balanço hídrico (BH) e de sinais radiológicos de congestão pulmonar antes do TRE sobre os desfechos no desmame também precisam ser determinados. Métodos: Cinquenta e sete indivíduos elegíveis para o desmame ventilatório foram recrutados. Traqueostomizados foram excluídos. Realizou-se avaliação ultrassonográfica de seis zonas pulmonares imediatamente antes e ao final do TRE. Predominância B foi definida como qualquer perfil com padrão B presente bilateralmente em região torácica anterior. Os pacientes foram seguidos por até 48 horas depois da extubação. Após esse estudo piloto, foi conduzido um estudo observacional, prospectivo, multicêntrico em duas unidades de terapia intensiva (UTIs) clínico-cirúrgicas ao longo de dois anos. Os mesmos critérios de inclusão e de exclusão foram aplicados; contudo, a ultrassonografia foi realizada apenas antes do TRE. O desfecho primário foi falha no TRE, definido como incapacidade de tolerar o teste T durante 30 a 120 minutos e, nesse caso, o paciente não era extubado. Dados demográficos e fisiológicos, BH das 48 horas antecedendo o TRE (entrada de fluidos menos débitos durante 48 horas) e desfechos foram coletados. Em uma análise post hoc de 170 procedimentos de desmame, um radiologista aplicou um escore radiológico na interpretação de radiografias digitais de tórax realizadas previamente ao TRE – o exame mais recente disponível foi avaliado em termos de congestão pulmonar. Resultados: No estudo piloto, 38 indivíduos foram extubados com sucesso, 11 falharam no TRE e 8 necessitaram de reintubação em até 48 horas após a extubação. No início do teste T, padrão B ou consolidação já estava presente em porções inferiores e posteriores dos pulmões em mais da metade dos casos, e tais regiões mantiveram-se não aeradas até o final do teste. Perda de aeração pulmonar durante o TRE foi observada apenas no grupo que falhou no mesmo (p= 0,07). Esses pacientes também demonstraram maior predominância B ao final do teste (p= 0,019). Antes do procedimento de desmame, todavia, não foi possível discernir indivíduos que falhariam no TRE, tampouco aqueles que necessitariam de reintubação dentro de 48 horas. Posteriormente, de 2011 a 2013, 250 procedimentos de desmame foram avaliados. Falha no TRE ocorreu em 51 (20,4%). Cento e oitenta e nove pacientes (75,6%) foram extubados na primeira tentativa. Indivíduos que falharam no TRE eram mais jovens (mediana de 66 versus 75 anos, p= 0,03) e apresentaram maior duração de VM e maior prevalência de doença pulmonar obstrutiva crônica (DPOC) (19,6 versus 9,5%, p= 0,04). Predominância B mostrou-se um preditor muito fraco para falha no TRE, exibindo sensibilidade de 47%, especificidade de 64%, valor preditivo positivo de 25% e valor preditivo negativo de 82%. Não houve diferença estatisticamente significativa no BH das 48 horas antecedendo o TRE entre os grupos (falha no TRE: 1201,65 ± 2801,68 ml versus sucesso no TRE: 1324,39 ± 2915,95 ml). Entretanto, em pacientes portadores de DPOC, ocorreu associação estatisticamente significativa entre BH positivo nas 48 horas antes do TRE e falha no TRE (odds ratio= 1,77 [1,24 – 2.53], p= 0,04). O escore radiológico, obtido em 170 testes T, foi similar entre os pacientes com falha e sucesso no TRE (mediana de 3 [2 – 4] versus 3 [2 – 4]), p= 0, 15). Conclusão: Maior perda de aeração pulmonar observada à ultrassonografia durante o TRE pode sugerir disfunção cardiovascular e aumento na água extravascular, ambos induzidos pelo processo de desmame. BH, sinais radiológicos de congestão pulmonar ou padrão B documentado através de um protocolo ultrassonográfico simplificado não devem contraindicar o TRE em pacientes estáveis hemodinamicamente e adequadamente oxigenados, haja vista o fato de tais variáveis não terem predito maior probabilidade de falha de desmame em pacientes críticos clínico-cirúrgicos. Ainda assim, evitar BH positivo em pacientes com DPOC parece otimizar os desfechos do desmame. / Introduction: Both delayed and premature liberation from mechanical ventilation (MV) are associated with increased morbi-mortality. Inspiratory fall in intra-thoracic pressure during spontaneous breathing trial (SBT) may precipitate cardiac dysfunction through abrupt increase in venous return and in left ventricular afterload. Changes in respiratory and cardiac load occurring throughout SBT might manifest with dynamic changes in lung ultrasound (LUS). B-pattern is an artifact that correlates with interstitial edema. A randomized controlled trial concluded that bedside LUS could predict post extubation distress due to changes in lung aeration throughout weaning procedure; however, it could not screen patients before submission to SBT. The impact of fluid balance (FB) as well as of radiological signs of pulmonary congestion prior to SBT on weaning outcomes must also be determined. Methods: Fifty-seven subjects eligible for ventilation liberation were enrolled. Patients with tracheostomy were excluded. LUS assessment of six thoracic zones was performed immediately before and at the end of SBT. B-predominance was defined as any profile with anterior bilateral B-pattern. Patients were followed up to 48 hours after extubation. After this pilot report, we conducted a 2-year prospective, multicenter, observational study in two adult medical surgical intensive care units (ICUs). Same inclusion and exclusion criteria were applied; however, LUS was performed only immediately before SBT. The primary outcome was SBT failure, defined as inability to tolerate a T-piece trial during 30 to 120 minutes, in which case patients were not extubated. Demographic, physiologic, FB in the preceding 48 hours of SBT (fluid input minus output over the 48-hour period), and outcomes data were collected. As a post hoc analysis in 170 weaning procedures performed in one of the ICUs, an attending radiologist applied a radiological score on interpretation of digital chest x-rays performed before SBT - the most recent available exam was analyzed regarding degree of lung fluid content. Results: In the pilot study, 38 subjects were successfully extubated, 11 failed the SBT and 8 needed reintubation within 48 hours of extubation. At the beginning of T-piece trial, B-pattern or consolidation were already found at lower and posterior lung regions in more than half of the individuals and remained nonaerated at the end of the trial. Loss of lung aeration during SBT was observed only in SBT-failure group (p= 0.07). These subjects also exhibited higher B-predominance at the end of trial (p= 0.019). Prior to weaning procedure, however, we were not capable to discriminate individuals who would fail SBT, nor who would need reintubation within 48 hours. Afterwards, from 2011 to 2013, 250 weaning procedures were evaluated. SBT failure occurred in 51 (20.4%). One hundred eighty-nine patients (75.6%) were extubated at first attempt. Individuals who failed SBT were younger (median 66 versus 75 years, p= 0.03), had higher duration of MV (median 7 versus 4 days, p< 0.0001) and higher prevalence of chronic obstructive pulmonary disease (COPD) (19.6 versus 9.5%, p= 0.04). B-predominance was a very weak predictor for SBT failure, showing 47% sensitivity, 64% specificity, 25% positive predictive value, and 82% negative predictive value. There were no statistically significant differences in 48 hour-FB prior to SBT between groups (SBT failure: 1201.65 ± 2801.68 mL versus SBT success: 1324.39 ± 2915.95 mL). However, in COPD subgroup, we found significant association between positive FB in the 48 hours prior to SBT and SBT failure (odds ratio = 1.77 [1.24 – 2.53], p= 0.04). Radiological score, obtained in 170 T-piece trials, was similar between SBT failure and success subjects (median 3 [2 - 4] vs 3 [2 - 4], p= 0.15). Conclusion: Higher loss of lung aeration observed by LUS during SBT might suggest cardiovascular dysfunction and increases in extravascular lung water, both induced by weaning. Neither FB, nor radiological findings of pulmonary congestion, nor B-pattern detected by a simplified LUS protocol should preclude hemodynamically stable, sufficiently oxygenated patients from performing an SBT, since such variables did not predict greater probability of weaning failure in medical-surgical critically ill population. Notwithstanding, avoiding positive FB in COPD patients might improve weaning outcomes.

Introdução: Descontinuação prematura ou tardia da ventilação mecânica invasiva (VM) associa-se a maior morbimortalidade. Redução da pressão intratorácica durante o teste de respiração espontânea (TRE) pode precipitar disfunção cardíaca através da elevação abrupta do retorno venoso e da pós-carga do ventrículo esquerdo. Da mesma maneira, alterações na demanda respiratória e cardíaca que ocorrem ao longo do TRE também podem manifestar-se à ultrassonografia pulmonar. O padrão B é um artefato sonográfico que se correlacionada com edema intersticial. Um ensaio clínico randomizando concluiu que a ultrassonografia pulmonar foi capaz de prever insuficiência ventilatória pós extubação através de variações na aeração pulmonar observadas durante o procedimento de desmame; contudo, a ferramenta não pôde rastrear pacientes antes da submissão ao TRE. O impacto do balanço hídrico (BH) e de sinais radiológicos de congestão pulmonar antes do TRE sobre os desfechos no desmame também precisam ser determinados. Métodos: Cinquenta e sete indivíduos elegíveis para o desmame ventilatório foram recrutados. Traqueostomizados foram excluídos. Realizou-se avaliação ultrassonográfica de seis zonas pulmonares imediatamente antes e ao final do TRE. Predominância B foi definida como qualquer perfil com padrão B presente bilateralmente em região torácica anterior. Os pacientes foram seguidos por até 48 horas depois da extubação. Após esse estudo piloto, foi conduzido um estudo observacional, prospectivo, multicêntrico em duas unidades de terapia intensiva (UTIs) clínico-cirúrgicas ao longo de dois anos. Os mesmos critérios de inclusão e de exclusão foram aplicados; contudo, a ultrassonografia foi realizada apenas antes do TRE. O desfecho primário foi falha no TRE, definido como incapacidade de tolerar o teste T durante 30 a 120 minutos e, nesse caso, o paciente não era extubado. Dados demográficos e fisiológicos, BH das 48 horas antecedendo o TRE (entrada de fluidos menos débitos durante 48 horas) e desfechos foram coletados. Em uma análise post hoc de 170 procedimentos de desmame, um radiologista aplicou um escore radiológico na interpretação de radiografias digitais de tórax realizadas previamente ao TRE – o exame mais recente disponível foi avaliado em termos de congestão pulmonar. Resultados: No estudo piloto, 38 indivíduos foram extubados com sucesso, 11 falharam no TRE e 8 necessitaram de reintubação em até 48 horas após a extubação. No início do teste T, padrão B ou consolidação já estava presente em porções inferiores e posteriores dos pulmões em mais da metade dos casos, e tais regiões mantiveram-se não aeradas até o final do teste. Perda de aeração pulmonar durante o TRE foi observada apenas no grupo que falhou no mesmo (p= 0,07). Esses pacientes também demonstraram maior predominância B ao final do teste (p= 0,019). Antes do procedimento de desmame, todavia, não foi possível discernir indivíduos que falhariam no TRE, tampouco aqueles que necessitariam de reintubação dentro de 48 horas. Posteriormente, de 2011 a 2013, 250 procedimentos de desmame foram avaliados. Falha no TRE ocorreu em 51 (20,4%). Cento e oitenta e nove pacientes (75,6%) foram extubados na primeira tentativa. Indivíduos que falharam no TRE eram mais jovens (mediana de 66 versus 75 anos, p= 0,03) e apresentaram maior duração de VM e maior prevalência de doença pulmonar obstrutiva crônica (DPOC) (19,6 versus 9,5%, p= 0,04). Predominância B mostrou-se um preditor muito fraco para falha no TRE, exibindo sensibilidade de 47%, especificidade de 64%, valor preditivo positivo de 25% e valor preditivo negativo de 82%. Não houve diferença estatisticamente significativa no BH das 48 horas antecedendo o TRE entre os grupos (falha no TRE: 1201,65 ± 2801,68 ml versus sucesso no TRE: 1324,39 ± 2915,95 ml). Entretanto, em pacientes portadores de DPOC, ocorreu associação estatisticamente significativa entre BH positivo nas 48 horas antes do TRE e falha no TRE (odds ratio= 1,77 [1,24 – 2.53], p= 0,04). O escore radiológico, obtido em 170 testes T, foi similar entre os pacientes com falha e sucesso no TRE (mediana de 3 [2 – 4] versus 3 [2 – 4]), p= 0, 15). Conclusão: Maior perda de aeração pulmonar observada à ultrassonografia durante o TRE pode sugerir disfunção cardiovascular e aumento na água extravascular, ambos induzidos pelo processo de desmame. BH, sinais radiológicos de congestão pulmonar ou padrão B documentado através de um protocolo ultrassonográfico simplificado não devem contraindicar o TRE em pacientes estáveis hemodinamicamente e adequadamente oxigenados, haja vista o fato de tais variáveis não terem predito maior probabilidade de falha de desmame em pacientes críticos clínico-cirúrgicos. Ainda assim, evitar BH positivo em pacientes com DPOC parece otimizar os desfechos do desmame. / Introduction: Both delayed and premature liberation from mechanical ventilation (MV) are associated with increased morbi-mortality. Inspiratory fall in intra-thoracic pressure during spontaneous breathing trial (SBT) may precipitate cardiac dysfunction through abrupt increase in venous return and in left ventricular afterload. Changes in respiratory and cardiac load occurring throughout SBT might manifest with dynamic changes in lung ultrasound (LUS). B-pattern is an artifact that correlates with interstitial edema. A randomized controlled trial concluded that bedside LUS could predict post extubation distress due to changes in lung aeration throughout weaning procedure; however, it could not screen patients before submission to SBT. The impact of fluid balance (FB) as well as of radiological signs of pulmonary congestion prior to SBT on weaning outcomes must also be determined. Methods: Fifty-seven subjects eligible for ventilation liberation were enrolled. Patients with tracheostomy were excluded. LUS assessment of six thoracic zones was performed immediately before and at the end of SBT. B-predominance was defined as any profile with anterior bilateral B-pattern. Patients were followed up to 48 hours after extubation. After this pilot report, we conducted a 2-year prospective, multicenter, observational study in two adult medical surgical intensive care units (ICUs). Same inclusion and exclusion criteria were applied; however, LUS was performed only immediately before SBT. The primary outcome was SBT failure, defined as inability to tolerate a T-piece trial during 30 to 120 minutes, in which case patients were not extubated. Demographic, physiologic, FB in the preceding 48 hours of SBT (fluid input minus output over the 48-hour period), and outcomes data were collected. As a post hoc analysis in 170 weaning procedures performed in one of the ICUs, an attending radiologist applied a radiological score on interpretation of digital chest x-rays performed before SBT - the most recent available exam was analyzed regarding degree of lung fluid content. Results: In the pilot study, 38 subjects were successfully extubated, 11 failed the SBT and 8 needed reintubation within 48 hours of extubation. At the beginning of T-piece trial, B-pattern or consolidation were already found at lower and posterior lung regions in more than half of the individuals and remained nonaerated at the end of the trial. Loss of lung aeration during SBT was observed only in SBT-failure group (p= 0.07). These subjects also exhibited higher B-predominance at the end of trial (p= 0.019). Prior to weaning procedure, however, we were not capable to discriminate individuals who would fail SBT, nor who would need reintubation within 48 hours. Afterwards, from 2011 to 2013, 250 weaning procedures were evaluated. SBT failure occurred in 51 (20.4%). One hundred eighty-nine patients (75.6%) were extubated at first attempt. Individuals who failed SBT were younger (median 66 versus 75 years, p= 0.03), had higher duration of MV (median 7 versus 4 days, p< 0.0001) and higher prevalence of chronic obstructive pulmonary disease (COPD) (19.6 versus 9.5%, p= 0.04). B-predominance was a very weak predictor for SBT failure, showing 47% sensitivity, 64% specificity, 25% positive predictive value, and 82% negative predictive value. There were no statistically significant differences in 48 hour-FB prior to SBT between groups (SBT failure: 1201.65 ± 2801.68 mL versus SBT success: 1324.39 ± 2915.95 mL). However, in COPD subgroup, we found significant association between positive FB in the 48 hours prior to SBT and SBT failure (odds ratio = 1.77 [1.24 – 2.53], p= 0.04). Radiological score, obtained in 170 T-piece trials, was similar between SBT failure and success subjects (median 3 [2 - 4] vs 3 [2 - 4], p= 0.15). Conclusion: Higher loss of lung aeration observed by LUS during SBT might suggest cardiovascular dysfunction and increases in extravascular lung water, both induced by weaning. Neither FB, nor radiological findings of pulmonary congestion, nor B-pattern detected by a simplified LUS protocol should preclude hemodynamically stable, sufficiently oxygenated patients from performing an SBT, since such variables did not predict greater probability of weaning failure in medical-surgical critically ill population. Notwithstanding, avoiding positive FB in COPD patients might improve weaning outcomes.