Abstract: Clinicians, perfusionists, and all those involved in cardiopulmonary bypass and hemostatic management rely on platelet function assays to make clinical decisions. Such decisions might include the administration of pharmaceuticals or the use of various blood products -- each of which has its own costs and risks associated with it. Therefore, it is critical that the data provided by the platelet function assays are accurate and used within the correct context.
A brief review of the literature indicates that clinical decisions seldom take into account the shortcomings associated with the various platelet function tests in use, particularly the associated lack of sensitivity and specificity. Clinicians use the results from these tests to guide hemostatic management despite a lack of evidence supporting their use in this manner. This project was designed to investigate several platelet function assays currently on the market including their advantages, disadvantages, and most appropriate uses.
It found that everything from the anticoagulant used to the method of collection may have a profound effect on the platelet function tests. This project summarizes the important considerations of each of the platelet function tests and provides recommendations for which assays to use in various situations. This project provides students, clinicians, and perfusionists with a concise guide to many platelet function assays currently available for use in hemostatic management and when they can be used effectively.
Abstract: There is little published research on the systematic analysis of pericardial effusions, in part because of the scarcity of these specimens in a laboratory setting. When they are analyzed, fluid chemistries, microbiology cultures, and cytologic evaluation are common, and are aimed at contributing to the determination of the etiology of the effusion. There are, however, limitations to the diagnostic utility of each of these tools. For example, even the normal ranges for determination of fluid chemistries is still up for debate. A better understanding of the predictive nature of clinical laboratory tests and cytopathology of pericardial fluid would aid both diagnosis and treatment. The objective of this study was to retrospectively analyze a large cohort of pericardial fluid specimens collected at a single facility in order to determine the relative incidences of the etiologies, and the benefit of clinical laboratory tests and cytopathology evaluation in determining those etiologies.
After IRB approval, both the Powerchart database and Cerner CoPath anatomic pathology database were searched for all patients with a pericardial effusion evaluated at Memorial Medical Center in Springfield, Illinois over a five-year period spanning January 1, 2009 to December 31, 2013. Clinical history, clinical laboratory data, cytopathology reports and surgical pathology reports were retrospectively reviewed. The data were used to determine if the test results supported the diagnosis and if incidence rates were comparable to those previously published.
In this study, a total of 74 pericardial effusions were obtained, representing 2.7% of all 2,760 fluid specimens (pleural=1,909; ascites=777) processed by the cytopathology laboratory during the five-year timeframe. A combination of laboratory tests were used to help determine their etiology. Chemistries such as LDH and total protein were not routinely run on the pericardial fluid specimens in this study as they are generally not helpful in determining the etiology of these effusions, as many of the parameters overlap. Microbiologic cultures and cytologic evaluation were proven to be valuable tools as both show a high sensitivity for detecting infection and malignancy, respectively. Although cytology is superior to pericardial biopsy in detecting malignancy, the combination of cytopathology and surgical pathology often allowed for a more definitive diagnosis. Knowledge of the usefulness and limitations of the laboratory tests employed in the fluid analysis will allow the clinician to best determine the specific etiology of the effusion and tailor treatment. The rates and causes of malignant specimens in this study were similar to those previously published by others.
Abstract: Over the past few decades the use of dietary creatine monohydrate has emerged as one of the most popular dietary ergogenic supplements. But some researchers have warned that such supplementation may not be entirely safe. This is based on multiple case reports that have indicated a possible link between creatine supplementation and renal dysfunction. Yet several studies have not supported a link between creatine supplementation and renal function, leaving many athletes to wonder what the risks of supplementation might be.
This review re-examines data associated with methods used to analyze renal function in individuals who supplemented with dietary creatine monohydrate. The emphasis of this review is on the various renal function marker methods [i.e., plasma creatinine (mg/dL), plasma urea (mg/dL), estimated creatinine clearance (ml/min), urinary creatinine (g/24hr), 51Cr-EDTA (ml/min), Cystatin C (mg/L), and urinary urea (g/24/hr)] as well as influential factors associated with the individuals that may have the potential to impact renal function (i.e., exercise, type of exercise, medicated, diseased, daily creatine intake, and length of creatine cycle). The combination of these data was imported into the statistical program Comprehensive Meta-Analysis (CMA). In all, a total of 21 studies were examined, which included 1,620 control subjects and 961 subjects treated with creatine. Data were compared in a variety of ways, including the comparisons of pre- and post-treatment urinary function markers via an unpaired t-test. The results of the unpaired t-tests found that plasma creatinine and estimated creatinine clearance (eCrnCl) were different before and after creatine supplementation (p<0.05), while other renal function markers did not differ. The groups assessed with plasma creatinine and estimated creatinine clearance were then evaluated individually against categorical moderators associated with exercise, medications, duration of creatine supplementation and pre-existing disease. Results indicated that the combination of exercise and consumption of high doses of creatine monohydrate for a short period of time, as well as consumption of the recommended dose for an extended period of time, had the greatest influence on levels of plasma creatinine (p<0.001) and estimated creatinine clearance (p<0.001).
Because both plasma creatinine and estimated creatinine clearance might change because of changes in creatine intake that are unrelated to renal function, it is recommended that additional clinical studies of creatine supplementation use either Cystatin C or 51Cr-EDTA as the measure of renal function. In this review, neither of these markers changed with creatine supplementation, and they would not be expected to be directly influenced by creatine intake. In summary, the determination of the impact of creatine supplementation on renal function may be confounded by the marker used to assess renal function, and choosing a marker that is not directly affected by creatine intake (independent of renal function) would provide the most reliable results.
Abstract: Mitral valve (MV) surgery is traditionally approached via median sternotomy. Robotic-assisted MV surgery is performed through smaller incisions and avoids the median sternotomy. By minimizing incisional trauma, robotic surgery is thought to yield superior patient outcomes to open sternotomy procedures. However, studies directly comparing patient outcomes of robotic and sternotomy MV surgeries are lacking in the literature. The purpose of this study is to provide a direct statistical comparison of short-term patient outcomes of robotic versus sternotomy MV surgeries at Aurora St. Luke's Medical Center in Milwaukee, Wisconsin.
Data were respectively obtained from the Society of Thoracic Surgeon's database. All patients who underwent robotic MV surgery were included in the study (n=55). A cohort of patients who underwent MV surgery via sternotomy were retrospectively selected based on equivalence of demographic characteristics, comorbidities, and medical history (n=230). Patients who had robotic MV surgery experienced longer CPB and cross-clamp times; fewer transfusions of packed red blood cells, platelets, fresh frozen plasma, and cryoprecipitate; shorter length of stay; and possible a shorter ICU length of stay. There were no significant differences in mechanical ventilation time, 30-day mortality, renal complications, heart block, reoperation for bleeding, new-onset atrial fibrillation, stroke, or 30-day readmission.
Abstract: The objective of this thesis is to report the results of a project entailing the design and testing of a mathematical model of the human aortic tree undergoing aortomyoplasty (AMP) treatment. AMP is a potential treatment for terminal heart failure, which produces a counterpulsation effect similar to that of the intra-aortic balloon pump (IABP). In AMP, skeletal muscle is wrapped around the outside of the patient's aorta, and paced to contract in a rhythm of counterpulsation with the heart. The skeletal muscle squeezes the walls of the aorta inward, producing an occlusion effect similar to the inflation of the IABP.
This model was adapted from an earlier work by Richard Hillestad, wherein the aorta was modeled as a lumped parameter electrical system of resistance, inductance, and capacitance. In Hillestad's paper, the electrical model of the aorta was constructed using physical electrical components, and the simulations consisted of running an electric current through the system and measuring the outputs.
The methods described in this thesis continued the work started by Hillestad. In this thesis, the ordinary differential state equations were derived for the lumped parameter model. These state equations were then encoded into a configurable set of routines in MATLAB. The MATLAB code is configurable, in that the researcher can easily vary several key components of the model, including the input pressure waveform; the resistance, compliance, and inertance; and the location and timing of the AMP treatment.
The results described in this thesis are promising. The state equations derived for the model produced similar results to the electric circuit built by Hillestad. The MATLAB routines also demonstrated the viability of this model to be configured for a variety of purposes. In addition, the modeling of AMP treatment was shown to be feasible using the framework of this model. More work will need to be done to ensure the accuracy of this model as an approximation of AMP treatment.
Abstract: The argument of when to transfuse a patient has been, and still is, a controversial issue in operating rooms around the country. Over the past few decades much research has focused on problems that are associated with transfusions. These problems included the chance of disease transmission and transfusion reactions which were associated with human-error during blood typing. More recently, it has been noted that postoperative complication risk rises with the use of packed red blood cells (pRBCs). Some of this research has focused on the complications associated with the age of transfused pRBCs. Several studies have noted the changes that occur within the storage lesion can increase mortality rates, length of hospital stay, renal and pulmonary insufficiency and infection rates.
This thesis focused on performing a retrospective study to investigate how the age of pRBCs correlated with postoperative complications. The study used data from coronary artery bypass grafting (CABG) patients at Saint Luke's Medical Center in Milwaukee, Wisconsin. The age of pRBCs administered were compared to various postoperative complications. This study also involved determining which risk factors were the best predictors of postoperative pulmonary insufficiency, postoperative renal failure, mortality and cardiac arrest.
Results indicated that the addition of pRBCs ≥ 14 days old increased a patient's risk of developing pulmonary insufficiency by 2.3 times. It was also found that the addition of pRBCs ≥ 14 days old also increased a patient's risk of developing renal failure, mortality, and cardiac arrest by 5.6 times.
Outcomes from this research show that there is increased risk associated with the administration of older pRBCs; however, because the population size was small, stronger associations between the age of pRBCs transfused and postoperative complications could not be made.