Perfusion
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Review
Interpreting studies of cognitive function following cardiac surgery: a guide for surgical teams.
Patients with coronary disease and related health care providers are faced with confusing and often conflicting information with regards to the neurocognitive impact of different strategies for coronary revascularization. Studies involving the measurement of postoperative cognitive deficit (POCD) have significant limitations that may ultimately impact on their interpretation and clinical relevance. In this review, we have described the origin of these tests and delineated the rationale for the design of testing that is commonly used in cardiac surgery patients. ⋯ For example, the impact of factors such as test/re-test reliability and practice effect can be mitigated by the use of an appropriately chosen control population. Liberal parlance of neurocognitive outcome as a rationale for therapeutic choice must be tempered by wise interpretation of these tests. It is only through the understanding of their limitations and the implications of trial design that we can translate these results to provide the best therapeutic options for our patients in unbiased manner.
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Review Comparative Study
Point of care hematocrit and hemoglobin in cardiac surgery: a review.
The use of point-of-care blood gas analyzers in cardiac surgery has been on the increase over the past decade. The availability of these analyzers in the operating room and post-operative intensive care units eliminates the time delays to transport samples to the main laboratory and reduces the amount of blood sampled to measure such parameters as electrolytes, blood gases, lactates, glucose and hemoglobin/hematocrit. Point-of-care analyzers also lead to faster and more reliable clinical decisions while the patient is still on the heart lung machine. ⋯ The literature indicates that using conductivity to measure hematocrit during and after cardiac surgery could produce inaccurate results when hematocrits are less than 30%, and, therefore, result in unnecessary homologous red cell transfusions in some patients. These inaccuracies are influenced by several factors that are common and unique to cardiopulmonary bypass, and will also be reviewed here. It appears that the only accurate, consistent and reliable method to determine hemodilution and establish transfusion thresholds based on nadir hematocrits during cardiopulmonary bypass, and immediately post cardiac surgery, is with the use of co-oximetry.
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Percutaneous femoral venous cannulation for cardiopulmonary bypass has emerged as an indispensable technique in the management of cardiac surgical procedures requiring cardiopulmonary bypass. A review of cases at Brigham and Women's Hospital (Boston, MA, USA) relying solely on percutaneous femoral venous cannulation for venous return to the heart-lung machine demonstrated achievable blood flow and complexity of case-load. Operations performed in this manner include, but are not limited to, coronary artery bypass grafting (CABG), valve, CABG/valve, and aortic procedures. ⋯ Complications of cardiopulmonary bypass and site-related complications were considered. Percutaneous femoral venous cannulation is a safe method to provide most patients with adequate venous return to perform any cardiac surgery. Patients demanding greater flow than this method will provide, may require a second venous cannula at some time during cardiopulmonary bypass.
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Medical devices are one of the most highly regulated products in the world. Despite this, there is an unacceptable rate of medical error. Not solely due to the device, but also the user and/or system in which it is used. ⋯ Medical devices are thoroughly tested before they are marketed, but we, as clinicians and users, must continuously examine and improve the design of equipment, procedures, personnel, and the environment in which we work to optimize medical systems. Once the device is on the market, changes or modifications are costly. Finally, a factor for success in critical testing of new devices is not what is technically possible, but rather making a concrete contribution to improving medical problems.
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Neurologic dysfunction remains the most significant complication associated with cardiopulmonary bypass (CPB). The insidious change of cognitive decline has been perceived as a key factor that has contributed to the shift to percutaneous intervention for coronary disease. Current neuropsychologic testing provides the most sensitive means of demonstrating clinically relevant cerebral damage of this nature. ⋯ Many of our daily practices in CPB management are based upon assumptions from observational studies without sound reference to evidence-based medicine. Our recent studies have challenged our assumptions related to ischemia and embolic events during CPB. They have also confirmed that, when high standards in trial design are applied, the results can have universal implications in terms of our practice.