Browsing by Author "Zygun, David A."
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Item Open Access The accuracy of pulse oximetry in emergency department patients with severe sepsis and septic shock: a retrospective cohort study(BioMed Central, 2010-05-05) Wilson, Ben J.; Cowan, Hamish J.; Lord, Jason A.; Zuege, Dan J.; Zygun, David A.Item Open Access Evidence for use of damage control surgery and damage control interventions in civilian trauma patients: a systematic review(2021-03-11) Roberts, Derek J.; Bobrovitz, Niklas; Zygun, David A.; Kirkpatrick, Andrew W.; Ball, Chad G.; Faris, Peter D.; Stelfox, Henry T.Abstract Background Although damage control (DC) surgery is widely assumed to reduce mortality in critically injured patients, survivors often suffer substantial morbidity, suggesting that it should only be used when indicated. The purpose of this systematic review was to determine which indications for DC have evidence that they are reliable and/or valid (and therefore in which clinical situations evidence supports use of DC or that DC improves outcomes). Methods We searched 11 databases (1950–April 1, 2019) for studies that enrolled exclusively civilian trauma patients and reported data on the reliability (consistency of surgical decisions in a given clinical scenario) or content (surgeons would perform DC in that clinical scenario or the indication predicted use of DC in practice), construct (were associated with poor outcomes), or criterion (were associated with improved outcomes when DC was conducted instead of definitive surgery) validity for suggested indications for DC surgery or DC interventions. Results Among 34,979 citations identified, we included 36 cohort studies and three cross-sectional surveys in the systematic review. Of the 59 unique indications for DC identified, 10 had evidence of content validity [e.g., a major abdominal vascular injury or a packed red blood cell (PRBC) volume exceeding the critical administration threshold], nine had evidence of construct validity (e.g., unstable patients with combined abdominal vascular and pancreas gunshot injuries or an iliac vessel injury and intraoperative acidosis), and six had evidence of criterion validity (e.g., penetrating trauma patients requiring > 10 U PRBCs with an abdominal vascular and multiple abdominal visceral injuries or intraoperative hypothermia, acidosis, or coagulopathy). No studies evaluated the reliability of indications. Conclusions Few indications for DC surgery or DC interventions have evidence supporting that they are reliable and/or valid. DC should be used with respect for the uncertainty regarding its effectiveness, and only in circumstances where definitive surgery cannot be entertained.Item Open Access A Health Technology Reassessment of Red Blood Cell Transfusions in the Intensive Care Unit(2019-08-23) Soril, Lesley Jeanne Josephine; Noseworthy, Tom W.; Clement, Fiona M.; Stelfox, Henry Thomas; Zygun, David A.Health technology reassessment (HTR) is the systematic, evidence-based assessment of the clinical, economic, ethical, and social impacts of an existing health technology to inform its optimal use. A novel model to guide HTR processes has been proposed. The overall aim of this thesis was to test the HTR model in a real-world healthcare context with the technology of red blood cell (RBC) transfusions in the intensive care unit (ICU). This thesis is comprised of 4 studies. The first study was a retrospective observational study of RBC transfusions in 9 Alberta ICUs. Between April 1, 2014 and December 31, 2016, we found that 61% of included RBC transfusions in stable, non-bleeding ICU patients were associated with a pre-transfusion hemoglobin value of 70 g/L or more and cost an estimated $1.82M in healthcare costs. Second, we conducted a systematic review and meta-analyses to determine the effectiveness of interventions on healthcare providers’ RBC transfusion practices. We identified a large and heterogenous body of evidence. Use of any intervention was associated with reduced odds of transfusion, including inappropriate transfusions. However, there was limited understanding of why interventions were selected over others and how this may have affected outcomes. In the third study, we conducted a population-based cross-sectional survey of Alberta ICU physicians to understand their perceptions of RBC transfusions practices using the Theoretical Domains Framework. We identified self-reported facilitators and barriers to practicing a guideline-recommended restrictive RBC transfusion strategy, which could then be mapped to relevant behaviour change interventions to optimize RBC transfusions. Finally, we conducted a controlled before and after pilot study to assess the feasibility of implementing a multi-modal intervention to optimize RBC transfusions in the ICU. The intervention was theory-informed and co-designed with local clinical leaders and included group education and audit and feedback. Early and meaningful stakeholder engagement and tailoring the intervention to interdisciplinary healthcare providers were important for achieving feasibility. Overall, we uncovered critical methodological and practical considerations to advance the emerging field of HTR. With regards to optimizing RBC transfusions, we established the necessary foundation to implement, monitor, and evaluate a larger-scale HTR initiative for ICUs in Alberta.Item Open Access Understanding Brain Injury-Induced Immunosuppression and the Relationship to the Development of Infection(2018-06-05) Scott, Brittney Noelle Vivian; Kubes, Paul; Zygun, David A.; Kramer, Andreas H.; Ousman, Shalina S.; Schryvers, Anthony B.; Fox-Robichaud, Alison E.Infection is a leading cause of morbidity and mortality among hospitalized patients. It has become increasingly apparent that patients with neurological injury have an increased risk for infection due to secondary immunodeficiency. Previous work from our research group found a novel role for invariant natural killer (iNKT) cells in stroke-induced immune suppression, characterized by a shift from a Th1- to Th2-dominant systemic cytokine profile and an increased risk for infection. This work better defined the crosstalk that occurs between the brain and systemic immune system after ischemic stroke, however, many questions remained and whether similar mechanisms were involved in other types of brain injury was unclear. Thus, we evaluated the relationship between iNKT cells, Th1 and Th2 systemic cytokine profiles, and the development of infection among critically ill patients with traumatic brain injury and haemorrhagic stroke. We found that these patients had significantly subnormal levels of many immune mediators, including IFN-γ and TNF-α, indicative of systemic immune suppression. Moreover, iNKT cells were activated among these patients and positively associated with plasma Th2/Th1 cytokine ratios. Infection was common and occurred among forty-six percent of the patients. Additionally, we used animal models to investigate traumatic brain injury-induced immune modulation and its relationship to infection. We observed rapid activation of iNKT cells in the circulation and a >2-fold increase in plasma Th2/Th1 cytokine ratios, which peaked at 8 hours after injury. Remarkably, we also observed rapid changes in the lung microenvironment induced by traumatic brain injury, which influenced the outcome after infection. Moreover, in an attempt to better understand the epidemiology of infection among patients with traumatic brain injury, we conducted a systematic review of the world’s literature on this topic. We summarize and discuss the reported occurrence rates of infection, and the microbiology and risk factors associated with different types of infection, among patients hospitalized after traumatic brain injury. This thesis provides new insights into the relationship between brain injury and the development of infection. Understanding the unique risk for infection after acute brain injury will ultimately translate to better prevention and treatment regimens for these patients.