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.
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.
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.
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.
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.
During hypothermic cardiopulmonary bypass (CPB) patients are cooled, usually to between 30-32 degrees C, and, after myocardial blood flow is restored, they are rewarmed with blood heated in the pump-oxygenator. We audited our local practice by recording tympanic and nasopharyngeal temperatures in 11 patients undergoing hypothermic CPB. We found that, during rewarming, nasopharyngeal and tympanic temperatures commonly exceeded 38 degrees C although temperature measured in the bladder was
Comment In: Can J Anaesth. 1995 Aug;42(8):663-87586102
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.
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.
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.
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.