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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. In general, neurocognitive tests assess domains of memory/new learning, psychomotor speed/dexterity and attentional capacity/mental control. Pre- and post-intervention tests in each domain can be evaluated either by the measurement of mean change scores (Group Comparison Model) for the entire group as continuous data, or by using categorical or continuous data to examine patterns of individual decline (Individual Comparison Model). This latter approach requires a specific definition of what constitutes a decline, which can be criticized as being arbitrary. There are limitations to each of these approaches that necessitate that critical information in trial design is available to the reviewer to facilitate interpretation. 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. Perfusion (2007) 22, 185—192.

Introduction: Despite major advances in biomaterial research and blood conservation, bleeding is still a common complication after cardiopulmonary bypass and cardiac surgery remains a major consumer of blood products. Although the underlying mechanisms for these effects are not fully established, two proposed major etiologies are the hemodilution associated with the use of the heart-lung machine and the impact of reinfusion of shed cardiotomy blood. Therapeutic strategies that primarily encompass the use of devices or technologies to overcome these effects may result in improved clinical outcomes. Objective: To determine the extent to which 1) lipid/leukocyte filtration and centrifugal processing of cardiotomy blood, and 2) modified ultrafiltration (MUF) are currently applied in adult cardiac surgery in Canada. Methods: A questionnaire was mailed to the chief perfusionist at all adult cardiac surgical centers in Canada, addressing details regarding the frequency of use of cardiotomy blood processing and MUF. Results: All questionnaires (36, 100%) were completed and returned. With regards to cardiotomy blood management, in 21 centers (58%), no specific processing steps were utilized exclusive of the integrated cardiotomy reservoir filter. Of the remaining centers, two (6%) reported using lipid/leukocyte filtration and 15 (42%) reported washing their cardiotomy blood. Three centers (8%) reported using MUF at the end of CPB. Conclusions: Despite growing concern about the potential detrimental effects of cardiotomy blood, few centers in Canada routinely manage this blood with additional filtration and/or centrifugal processing prior to reinfusion. Similarly, MUF, demonstrated to be effective in the pediatric population, has not seen popular application in adult cardiac surgical practice.

Background: Mild to moderate systemic hypothermia is commonly used as a cerebral protective strategy during adult cardiac surgery. The benefits of this strategy for routine cardiac surgery have been questioned and the adverse effects of hyperthermia demonstrated. The purpose of the present study was to examine current temperature management and monitoring practices during adult cardiac surgery using CPB in Canada.Methods: Web-based survey referring to adult cases undergoing cardiac surgery using CPB without the use of deep hypothermic circulatory arrest. Thirty-two questionnaires were completed, representing a 100% response rate.Results: The usual management is to cool patients during CPB at 30 (94%) centers for low-risk (isolated primary CABG) cases and at 31 (97%) centers for high-risk (all other) cases. The average nadir temperature at the target site achieved on CPB is 34°C (range 28°C - 36°C). At 26 (81%) centers, patients are typically rewarmed to a target temperature between 36°C and 37°C before separation from CPB. Only 6 (19%) centers reported that thermistors and coupled devices used to monitor blood temperature are checked for accuracy or calibrated according to the product operating directive’s schedule or more often.Conclusions: Contemporary management of adult cardiac surgery under CPB still involves induction of mild to moderate systemic hypothermia. Significant practice variation exists across the country with respect to target temperatures for cooling and rewarming, as well as the site for temperature monitoring. This probably reflects the lack of definitive evidence. There is a need for well-conducted clinical trials to provide more robust evidence regarding temperature management.

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. Through extensive experience in randomized clinical trials of over 900 patients undergoing CPB, our team has addressed several key hypotheses related to the embolic/ischemic nature of cerebral injury in cardiac surgery, using this testing. In the first temperature study, patients randomized to hypothermia with passive re-warming had a lower incidence of neurocognitive deficit when compared with those patients who were actively re-warmed to 37°. In order to clarify the role of the hypothermia as opposed to the re-warming process, a second temperature study was completed. In the hypothermic group, patients were cooled and maintained at 34° with no active re-warming whereas, in the normothermic group, the patients were kept at 37° throughout the perioperative period. No difference in neurocognitive outcome in the two groups was seen, implying that the benefit seen in the first temperature study was related not to the hypothermia, but rather to the absence of active re-warming. In the cardiotomy study, patients were randomized to either a control group in which their cardiotomy blood was returned unprocessed, or a treatment group in which this blood was sequestered and processed with centrifugal washing and fat filtration. No significant difference in neurocognitive outcome was found in these two groups. On the other hand, there was a significant increase in bleeding and transfusion requirements in the treatment group. 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. Perfusion (2007) 22, 153—160.

Objective: To determine the association between high-intensity transient signals (HITS) and perfusionist interventions, purging techniques, pump flows and venous reservoir blood volume levels during cardiopulmonary bypass. Methods: Transcranial Doppler was used to detect HITS in the middle cerebral artery during the period of aortic crossclamping in patients undergoing coronary artery bypass grafting. Perfusionist-related interventions were recorded and included blood sampling (including the number of times that the oxygenator sampling manifold was purged), drug bolus injections and infusions (vasopressors, crystalloid and mannitol). Pump flows and venous reservoir volume levels were also documented. Results: There were 534 interventions in 90 patients [median number of interventions per patient: 6 (quartiles: 4, 8)]. The median total HITS count from all interventions was 17 (5, 37). This represented 38% of the total HITS counts during aortic crossclamping. Factors contributing to differences in the HITS count included type of intervention ( p Conclusions: Cerebral emboli associated with perfusionist interventions can be minimized by not purging the sampling manifold, using continuous infusions rather than bolus injections, and maintaining high blood-volume levels (>800 mL) in the venous reservoir.