***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: Recent reports have described cerebral venous oxygen desaturation during and after rewarming from hypothermic cardiopulmonary bypass . Additionally , patients undergoing normothermic cardiopulmonary bypass  may be at higher risk for neurologic injury . This study was design ed to determine whether patients undergoing normothermic cardiopulmonary bypass  are at increased risk for sustained cerebral desaturation . Fifty-two patients undergoing first-time coronary artery bypass grafting were r and omized to receive normothermic ( 37 degrees C , n = 26 ) or hypothermic ( 27 degrees C , n = 26 ) cardiopulmonary bypass .  The anesthetic was st and ardized and alpha-stat pH management was used . A 4F oximetric catheter was placed in the jugular bulb and cerebral venous and radial arterial blood were sample d.  Oxygen partial pressure and saturation were measured at six intervals from cerebral venous blood and from radial arterial blood . Patients receiving  normothermic cardiopulmonary bypass had lesser values of oxygen partial pressure and saturation in cerebral venous blood than patients subjected to hypothermia during the first 40 minutes of bypass . Cerebral venous desaturation ( oxygen saturation in cerebral venous blood of 50 % or less ) was observed in 54 % of patients in the normothermic group and 12 % of patients in the hypothermic group during cardiopulmonary bypass . In the normothermic group , cerebral desaturation occurred primarily in early bypass ( 14 of 26 ) . The three episodes of desaturation in the hypothermic group occurred during rewarming . During cardiopulmonary bypass , the arteriovenous oxygen content difference was greater in the normothermic group than in that in the hypothermic group , suggesting higher oxygen consumption . Differences in glucose utilization during early cardiopulmonary bypass between the groups was also detected . One patient in the hypothermic group had an embolic stroke and subsequently died . There were no other perioperative strokes or deaths in the study population . The present study demonstrates that patients undergoing normothermic cardiopulmonary bypass are at greater risk for cerebral desaturation . Because it is a global assessment , cerebral venous oxygen saturation may be insensitive to focal ischemic events . It remains to be seen whether these differences in cerebral physiologic states translate into differences in clinical outcome Several studies suggest that normothermic ( " warm " ) bypass techniques may improve myocardial outcomes for patients undergoing cardiac operations . Normothermic temperatures during cardiopulmonary bypass may , however , decrease the brain 's tolerance to the ischemic insults that accompany all cardiac procedures . To assess the effect of bypass temperature management strategy on central nervous system outcomes in patients undergoing coronary revascularization , 138 patients were r and omly assigned to two treatment groups : ( 1 )  hypothermia ( n = 70 ) , patients cooled to a temperature less than 28 degrees C during cardiopulmonary bypass , or ( 2 ) normothermia ( n = 68 ) , patients actively warmed to a temperature of at least 35 degrees C. Patients underwent detailed neurologic examination before the operation , on postoperative days 1 to 3 and 7 to 10 , and at approximately 1 month after operation . In addition , a battery of five neuropsychologic tests was administered before operation , on postoperative days 7 to 10 , and at the 4- to 6-week follow-up visit . Patients in the normothermic treatment group were older ( 65 + /- 10 vs 61 + /- 11 years in the hypothermic group ) , had statistically less likelihood of preexisting cerebrovascular disease , and had higher  bypass blood glucose values  ( 276 + /- 100 mg/% vs. 152 + /- 66 mg/% in the hypothermic group ) . All other patient characteristics and intraoperative variables were similar in the two treatment groups . Seven of 68 patients in the normothermic group were found to have a central neurologic deficit , compared with none of the patients cooled to 28 degrees C ( p = 0.006 ) . Performance on at least one neuropsychologic test deteriorated in the immediate postoperative period in more than one half of all patients in both treatment groups but returned to preoperative levels approximately 1 month after the operation in most ( 85 % ) . This pattern was not related to bypass temperature management strategy . We conclude that active warming during cardiopulmonary bypass to maintain systemic temperatures > or = 35 degrees C increases the risk of perioperative neurologic deficit in patients undergoing elective coronary revascularization BACKGROUND Continuous retro grade blood cardioplegia has been introduced as a promising alternative for myocardial protection during cardiac operations , although the optimal conditions for its delivery have been poorly studied . METHODS We r and omized a prospect i ve series of 101 patients to receive either retro grade warm ( 37 degrees C ) or mild hypothermic ( 28 degrees to 29 degrees C ) blood cardioplegia during elective coronary artery bypass grafting . Warm blood cardioplegia was delivered to the aortic root until the heart was arrested , after which the regimen was switched to retro grade and continued either as warm or mild hypothermic cardioplegia .  Oxygen consumption and transcardiac pH differences during aortic cross-clamping were determined , and postoperative creatine kinase-MB efflux , hemodynamic recovery , and clinical complications monitored . RESULTS Clinical characteristics , cardioplegia delivery rates , aortic cross-clamp and cardiopulmonary bypass times , and the number of distal anastomoses were similar in both patient groups . Short intermissions in cardioplegia delivery during construction of distal anastomoses were allowed , the ischemia time in the mild hypothermic group being somewhat longer ( 8.3 % + /- 1.1 % versus 5.1 % + /- 0.8 % of cross-clamp time ; p = 0.05 ) . Myocardial oxygen consumption was lower in the mild hypothermic group ( 2.49 + /- 0.23 versus 3.93 + /- 0.33 mL/min at 30 minutes of cross-clamping ; p < 0.01 ) , and the transcardiac pH difference was smaller ( 0.05 + /- 0.01 versus 0.07 + /- 0.01 at 30 minutes of cross-clamping ; p < 0.03 ) . Postoperative creatine kinase-MB levels were higher in the normothermic group . Heart rate was higher and left ventricular stroke work index smaller in the warm group , but otherwise there were no major differences between the groups in hemodynamic recovery . The number of postoperative complications was also similar in both groups . CONCLUSIONS Although both normothermic ( 37 degrees C ) and mild hypothermic ( 28 degrees to 29 degrees C ) retro grade blood cardioplegia , when delivered in near-continuous fashion , will offer safe myocardial protection during coronary artery bypass grafting , mild hypothermia seemed to provide somewhat better protection under the conditions prevailing here . The effects of different cardioplegia temperatures should perhaps be tested further in patients with recent myocardial infa rct ion , unstable angina , or severely depressed left ventricular function A prospect i ve 5 years ' neuropsychological , neurological , cardiological and electroencephalographical follow-up study was carried out in 44 patients who had undergone open-heart surgery for valve replacement .  A distinct interrelationship was found between the clinical outcome immediately after operation and the neuropsychological long-term course despite the rapid recovery of occasional clinical disorders related to operative procedures . In fact , the psychometric performance scores of those who did not develop clinical signs of cerebral dysfunction induced in operation showed a significant difference only years after operation . Similarly , the harmful effects of long perfusion time ( extracorporeal circulation ) in operation were reflected in the long-term neuropsychological performance . Some evidence seemed to suggest that the correction of the prolonged circulatory disorder might possibly afford real enhancement of higher cerebral functions . The long-term results not only emphasize the importance of a careful clinical evaluation but also emphasize the necessity of considering the sub clinical level of events both before and after operation when assessing the overall outcome and cerebral safety of cardiac surgery patients BACKGROUND Transient right ventricular dysfunction has been previously documented after bypass operations despite adequate myocardial protection with intermittent ante grade cold blood cardioplegia . Recently warm blood cardioplegia has been interrupted during construction of distal anastomoses to improve visualization . The effects of intermittent ante grade warm blood cardioplegia , and the result ant periods of right ventricular normothermic ischemia , on postoperative right ventricular function are unknown . METHODS To assess the effects of cardioplegia on right ventricular protection , 52 patients undergoing isolated bypass grafting were r and omized to intermittent warm or cold blood cardioplegia .  The two groups were similar with respect to age , sex , ventricular function , and right coronary stenoses . Cross-clamp times were similar ( warm , 64 + /- 22 minutes ; cold , 63 + /- 15 minutes ; not significant ) . The cumulative time of cardioplegia interruption was longer in the cold group ( 42 + /- 8 minutes ) than in the warm group ( 31 + /- 14 minutes ; p < 0.002 ) . A rapid-response thermodilution catheter was employed to assess postoperative right ventricular ejection fraction and end-diastolic and end-systolic volume indices . RESULTS The right ventricular ejection fraction was greater in the warm group at 6 hours ( warm , 0.46 + /- 0.06 ; cold , 0.37 + /- 0.08 ; p < 0.05 ) and 8 hours ( warm , 0.43 + /- 0.08 ; cold , 0.37 + /- 0.08 ; p < 0.05 ) postoperatively . The right ventricular end-diastolic volume index was less in the warm group 8 hours postoperatively ( warm , 83 + /- 11 mL/m2 ; cold , 94 + /- 16 mL/m2 ; p < 0.05 ) . There were no differences in pulmonary arterial pressures or right ventricular stroke work index . CONCLUSIONS Despite intermittent normothermic ischemia of half the cross-clamp time , patients receiving warm cardioplegia maintained right ventricular hemodynamics after bypass grafting BACKGROUND The objective of this r and omized clinical trial of  elective coronary artery bypass grafting  was to investigate whether intraoperative mean arterial pressure below autoregulatory limits of the coronary and cerebral circulations was a principal determinant of postoperative complications . The trial compared the impact of two strategies of hemodynamic management during cardiopulmonary bypass on outcome . Patients were r and omized to a low mean arterial pressure of 50 to 60 mm Hg or a high mean arterial pressure of 80 to 100 mm Hg during cardiopulmonary bypass . METHODS A total of 248 patients undergoing primary , nonemergency coronary bypass  were r and omized to either low ( n = 124 ) or high ( n = 124 ) mean arterial pressure during cardiopulmonary bypass . The impact of the mean arterial pressure strategies on the following outcomes was assessed : mortality , cardiac morbidity , neurologic morbidity , cognitive deterioration , and changes in quality of life . All patients were observed prospect ively to 6 months after the operation . RESULTS The overall incidence of combined cardiac and neurologic complications was significantly lower in the high pressure group at 4.8 % than in the low pressure group at 12.9 % ( p = 0.026 ) . For each of the individual outcomes , the trend favored the high pressure group . At 6 months after coronary bypass for the high and low pressure groups , respectively , total mortality rate was 1.6 % versus 4.0 % , stroke rate 2.4 % versus 7.2 % , and cardiac complication rate 2.4 % versus 4.8 % . Cognitive and functional status outcomes did not differ between the groups . CONCLUSION Higher mean arterial pressures during cardiopulmonary bypass can be achieved in a technically safe manner and effectively improve outcomes after coronary bypass OBJECTIVE To analyze the frequency and severity of sub clinical cerebral complications associated with  coronary artery bypass grafting ( CABG ) .  DESIGN A prospect i ve controlled study using preoperative and postoperative magnetic resonance imaging ( MRI ) of the brain , quantitative electroencephalography ( QEEG ) , and detailed neuropsychological and neurologic examinations as potentially sensitive indicators of sub clinical cerebral injury associated with CABG . SETTING Multimodality evaluation in a tertiary care unit ( Kuopio University Hospital , Kuopio , Finl and ) . PATIENTS Thirty-eight patients undergoing elective CABG and 20 control patients undergoing other major vascular surgery , mostly operations on the abdominal aorta .  MAIN OUTCOME MEASURES Coronary artery bypass grafting-associated cerebral complications assessed preoperatively and postoperatively by  brain MRI , QEEG , detailed neurologic examination , and a neuropsychological test battery that evaluates cognitive functions in major areas known to be vulnerable to organic impairment ( learning and memory , attention , flexible mental processing , and psychomotor speed ) . RESULTS There were no major ne 
    Output:
    
REVIEW ER 'S CONCLUSIONS This review could find no definite advantage of hypothermia over normothermia in the incidence of clinical events .
Hypothermia was associated with a reduced stroke rate , but this is off set by a trend towards an increase in non stroke related perioperative mortality and myocardial damage .