***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: OBJECTIVES To evaluate the effect of on-pump and off-pump coronary artery bypass grafting ( CABG )  on  postoperative cognitive impairment and cerebrovascular reactivity , with attention for the perioperative high-intensity transient signals ( HITS ) . DESIGN A prospect i ve comparative study . SETTING Urban university hospital . PATIENTS C and i date s for cardiac surgery . METHODS Measurement of HITS as a reflection of embolic load was performed in 50 patients ( on-pump CABG , n = 32 ; off-pump CABG , n = 18 ) . To measure cognitively induced cerebrovascular reactivity , cerebral blood flow velocity ( BFV ) was measured preoperatively in 66 patients , early postoperatively ( after 6 days ) in 63 patients , and late postoperatively ( after 6 months ) in 44 patients during five cognitive tasks . In the same session , seven st and ardized neuropsychological tests were administered . RESULTS A higher embolic load was found in the on-pump group ( p < 0.01 ) . In the on-pump group , aortic cannulation was the most important HITS-prone surgical maneuver . Repeated- measures multivariate analysis of variance ( using surgical technique as between-subjects factor and significant differences between both groups as covariates ) on the group data revealed no significant differences in neuropsychological performance and BFV immediately after surgery or at 6 months after surgery , compared with preoperative performance . No main effect of surgery was found for neuropsychological performance and BFV . No significant correlations were found between the number of HITS and the degree of postoperative neuropsychological impairment . Individual comparisons revealed that 60 % ( 59.4 % in the on-pump group ; 61.1 % in the off-pump group ) of the patients undergoing CABG showed evidence of cognitive impairment soon after surgery . In 24.2 % , the cognitive sequelae persisted at 6 months follow-up ( 31.8 % in the on-pump group ; 9.1 % in the off-pump group ) . The cognitive impairment index ( sum of impaired neuropsychological tests ) showed a significant difference after 6 months between both surgery groups with fewer neurocognitive tests that remained impaired in the off-pump group . CONCLUSIONS In off-pump surgery , significantly fewer HITS were observed . On an individual level , more favorable results in neuropsychological test performance were demonstrated in the off-pump group after 6 months . The number of HITS showed no correlation with degrees of early and late postoperative neuropsychological impairment Delirium is an acute change in cognition which occurs frequently after coronary artery bypass graft ( CABG ) surgery . Cerebral microemboli , from plaque , air , or thrombus , have been hypothesized to contribute to delirium and cognitive decline after CABG . The purpose of this study was to determine if there was an association between cerebral microemboli and delirium after cardiac surgery . Non-delirious patients ( n=68 ) were prospect ively enrolled and underwent intraoperative monitoring of the middle cerebral arteries with transcranial Doppler ( TCD ) . TCD signals were saved and analyzed postoperatively for microemboli manually , according to established criteria . Postoperatively , patients were assessed for delirium with a st and ardized battery . Thirty-three patients ( 48.5 % ) developed delirium after surgery . Microemboli counts ( mean ± SD ) were not significantly different in those with and without delirium ( 303 ± 449 vs. 299 ± 350 ; p=0.97 ) . While intraoperative microemboli were not associated with delirium after CABG , further investigation into the source and composition of microemboli can further eluci date the long-term clinical impact of microemboli AIMS  Left heart catheterization  carries a risk for cerebral complications . The aims of this prospect i ve study were to determine the frequency and composition of catheterization-related cerebral microemboli and to detect cerebral morphological changes and acute cognitive impairment due to catheterization . METHODS AND RESULTS Forty-seven unselected patients undergoing elective left heart catheterization , either by transradial or by transfemoral access  , were monitored for cerebral microemboli using multifrequency transcranial Doppler . Cerebral magnetic resonance imaging ( MRI ) with diffusion-weighted imaging sequences and neuropsychological assessment s were carried out on the day before and the day after catheterization . A median number of 754 cerebral microemboli were detected : 92.1 % were gaseous and 7.9 % were solid . New cerebral lesions were observed in 15.2 % of the transradial , but none of the transfemoral , catheterization patients ( P=0.567 ) . These lesions were significantly associated with a higher number of solid microemboli ( P=0.016 ) and a longer fluoroscopy time ( P=0.039 ) . There was also a significantly higher number of solid microemboli during transradial than during transfemoral catheterization ( P=0.012 ) . Cognitive impairment following the investigations was associated with the degree of pre-catheterization cerebral MRI injury ( P=0.03 ) . CONCLUSION During left heart catheterization , cerebral microemboli , especially those which are solid , may damage the brain . Cardiac catheterization may therefore pose a greater risk for the brain than previously acknowledged OBJECTIVE In a r and omized trial of 223 patients undergoing coronary artery surgery with cardiopulmonary bypass , we have reported a neuroprotective effect of mild hypothermia . To determine whether the beneficial effect of mild hypothermia was long-lasting , we repeated the psychometric tests in 131 patients after 5 years . METHODS Patients were cooled to 32 degrees C during aortic crossclamping and then r and omized to rewarming to either 34 degrees C or 37 degrees C , with no further rewarming until arrival in intensive care unit . Cognitive function was measured preoperatively and 1 week and 5 years postoperatively with a battery of 11 psychometric tests interrogating verbal memory , attention , and psychomotor speed and dexterity . RESULTS Patients who had greater cognitive decline 1 week after surgery showed poorer performance 5 years later . The magnitude of cognitive decline over 5 years was modest . The incidence of deficits defined as a 1 st and ard deviation [ SD ] decline in at least 1 of 3 factors was not different between temperature groups . Fewer patients in the hypothermic group had deficits that persisted over the 5 years , but this difference did not attain statistical significance ( RR = 0.64 , P = .16 ) . CONCLUSIONS The effect of surgery on cognitive function observed early after surgery is an important predictor of cognitive performance 5 years later . Although there was evidence of a neuroprotective effect of mild hypothermia early after surgery in the original cohort , the results after 5 years were inconclusive . In general , the magnitude of cognitive changes over 5 years was modest . We believe that further trials investigating the efficacy of mild hypothermia in patients having cardiac surgery are warranted The purpose of our study was to investigate the association between perioperative cerebral microembolization , expressed as high-intensity transient signals ( HITS ) and postoperative dynamics of the neuromarker S100P in patients operated using cardiopulmonary bypass , and to assess their impact upon the neurocognitive function in the early postoperative stage . The study involved 62 consecutive male patients aged 60 or above , alls scheduled for elective aortocoronary bypass .  The patients were recruited from two groups with respect to the use of CPB : on-pump group ( CPB+ , N = 30 ) and off-pump group ( CPB- , N = 32 ) . In all patients we performed intraoperative monitoring of cerebral haemodynamics using transcranial Doppler , with the goal of quantifying perioperative cerebral microembolization . The serum levels of the neuromarker S100l  were measured immediately after surgery , and then 12 , 24 and 48 hours after the surgery . Neurocognitive status was assessed before and after the surgery and in three cognitive domains . Results of the study have shown that with respect to the short-term postoperative neurocognitive outcome there is no significant difference between the on-pump and off-pump surgical technique of coronary revascularization ' . Perioperative cerebral microembolization was significantly more pronounced in the on-pump group yet it did not affect early postoperative neurocognitive function , while the increase in the neuromarker S100beta serum level 48 hours after surgery may have prognostic value as a predictor of postoperative neurocognitive dysfunction Background and Purpose Microemboli have been implicated in the etiology of neuropsychological deficits after cardiopulmonary bypass . This study examined the incidence of high‐intensity transcranial signals ( microemboli ) and their relation to changes in neuropsychological performance after surgery . Methods Transcranial Doppler ultrasonography was used to measure middle cerebral artery blood flow velocity and detect microemboli . The number of high‐intensity transcranial signals was determined and related to a neurological examination and absolute changes in neuropsychological performance as well as the number of patients considered to exhibit a neuropsychological deficit . Data were available on 100 consenting patients undergoing routine cardiopulmonary bypass . Fifty of the patients were r and omly assigned to a procedure that included a 40‐&mgr;m arterial line filter , and 50 had the procedure without any arterial line filter . Results Significantly more patients were found to have neuropsychological deficits in the group without the arterial line filter at both 8 days ( P<.05 ) and 8 weeks ( P<.03 ) after surgery . In addition , more “ soft ” neurological signs were found in the nonfiltered group 24 hours after surgery ( P<.05 ) . More high‐intensity transcranial signals were found in the nonfiltered group , and the number of high‐intensity transcranial signals was found to be related to the likelihood of a patient having a neuropsychological deficit at 8 weeks . Conclusions These data suggest that neuropsychological deficits after routine cardiopulmonary bypass are related to the number of microemboli delivered during surgery . Furthermore , the numbers of microemboli may be reduced by including a 40‐&mgr;m filter on the arterial line . ( Stroke . 1994;25:1393‐1399 . Background —The risks that the presence of air microemboli implies in open-heart surgery have recently been emphasized by reports that their number is correlated with the degree of postoperative neuropsychological disorder . Therefore , we studied the effect of CO2 insufflation into the cardiothoracic wound on the incidence and behavior of microemboli in the heart and ascending aorta . Methods and Results —Twenty patients undergoing single-valve surgery were r and omly divided into 2 groups . Ten patients were insufflated with CO2 via a gas diffuser , and 10 were not .  Microemboli were ascertained by intraoperative transesophageal echocardiography ( TEE ) and recorded on videotape from the moment that the aortic cross-clamp was released until 20 minutes after end of cardiopulmonary bypass ( CPB ) . The surgeon performed st and ard de-airing maneuvers without being aware of TEE findings . Postoperatively , a blinded assessor determined the maximal number of gas emboli during each consecutive minute in the left atrium , left ventricle , and ascending aorta . The 2 groups did not differ in the usual clinical parameters . The median number of microemboli registered during the whole study period was 161 in the CO2 group versus 723 in the control group ( P < 0.001 ) . Corresponding numbers for the left atrium were 69 versus 340 ( P < 0.001 ) , left ventricle 68 versus 254 ( P < 0.001 ) , and ascending aorta 56 versus 185 ( P < 0.001 ) . In the CO2 group , the median number of detectable microemboli after CPB fell to zero 7 minutes after CPB versus 19 minutes in the control group ( P < 0.001 ) . Conclusions —Insufflation of CO2 into the thoracic wound markedly decreases the incidence of microemboli OBJECTIVE : The purpose of this study was to determine the correlation between transcranial Doppler ( TCD ) velocities and angiographic vasospasm  after aneurysmal subarachnoid hemorrhage . METHODS : In the first part of this study , patients were retrospectively review ed to correlate middle cerebral artery absolute blood flow velocities with angiographic vasospasm . In the second part of the study , the middle cerebral artery/ipsilateral extracranial internal carotid artery velocity ratio ( Lindegaard ratio ) was prospect ively correlated with angiographic vasospasm . Angiographic vasospasm was independently grade d , by observers blinded to the TCD results , as either none , mild ( less than one-third artery luminal narrowing ) , moderate ( one-third to one-half narrowing ) , or severe ( more than one-half narrowing ) . The sensitivity , specificity , likelihood ratios for positive and negative TCD results , 
    Output:
    
The findings of this review report that the current literature is divided as to whether the impact of embolization during cardiac surgery has any adverse impact on cognition .