***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: Leukocyte mediated pulmonary injury may delay recovery after cardiac surgery , and leukocyte depletion during bypass has been suggested . Two groups of patients were r and omly , prospect ively assigned from 50 sequential patients to undergo open heart surgery using cardiopulmonary bypass , either with ( n = 25 ) or without ( n = 25 ) leukocyte filters . The two groups were not significantly different regarding age , gender , race , pre-operative ejection fraction , pump time , or cross-clamp time . Post operative arterial blood gases ( pO2 : 173 + /- 66 vs 192 + /- 107 ; pCO2 : 30.2 + /- 8.2 vs 30.8 + /- 8.0 ) , pulmonary vascular resistance ( PVR 105 + /- 45 vs 112 + /- 50 dyne cm-5 ) , time on ventilator ( 17.8 + /- 6.4 vs 19.7 + /- 8.6 hr ) , and length of hospital stay ( 7.65 + /- 4.57 vs 8.52 + /- 5.87 days ) were not different between groups ( mean + /- SD , with vs without filters , respectively ) . Arterial oxygenation was somewhat poorer , and PVR was somewhat lower in the leukocyte filtered group . However , these trends did not produce significant decreases in total ventilator time or length of hospital stay . In-line filtration did remove leukocytes , but did not reduce circulating leukocyte count . In effect , leukocyte filtration produced an effective leukocyte concentration at the filter site . These data do not support routine incorporation of in-line leukocyte filtration during bypass 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 . INTRODUCTION Embolization of gaseous and particulate matter is incriminated in the neuropsychological morbidity of CPB and can be reduced by membrane oxygenators and arterial line filtration . It is not known if the use of arterial line filtration in conjunction with membrane oxygenators might have an additive effect in reducing cerebral injury . METHODS Forty patients undergoing elective coronary artery surgery were prospect ively r and omized to a 43 microns heparin coated arterial line filter ( Cobe Sentry ) or to no filtration ( control group ) . All operations were performed by one surgeon ( DPT ) using intermittent ischaemia with nonpulsatile CPB , a COBE CML membrane oxygenator and alpha-stat paCO2 management . Flow rates were maintained between 2.0 and 2.4 l-1 m2 per min with a perfusion pressure of 50 - 80 mmHg and a systemic temperature of 34 degrees C. Cerebral injury was defined by careful neurological examination and serial measurement of the serum concentration of S-100 protein ( a highly specific astroglial cell derivative , elevated serum levels of which correlate with proven cerebral injury ) . RESULTS There was no difference [ mean ( S.D. ) ] in the control and filter groups with respect to age [ 61(9 ) vs. 62(9 ) years ] , ejection fraction , number of grafts [ 2.8(0.6 ) vs. 2.6(0.7 ) ] or CPB times [ 55(19 ) vs. 57(18 ) min ] . Preoperatively , no patient had detectable S-100 . In the postoperative period 23 of 40 patients ( 58 % ) showed elevated S-100 levels . At 1 , 5 and 24 h the respective number of patients in the control and filter groups with elevated S-100 was ( 14 vs. 9 ) , ( 4 vs. 0 ) , ( 4 vs. 0 ) ) ( P < 0.05 ) . No patient had overt cerebral injury . CONCLUSIONS This study suggests that ( i ) sub clinical cerebral injury is common ( 58 % of patients in this study ) even after apparently uncomplicated surgery with short CPB times ; ( ii ) serum S-100 protein is a valuable marker for investigating potentially cerebral protective innovations during CPB ; and ( iii ) arterial line filtration significantly reduces but does not eliminate cerebral injury Background : Proteolytic enzymes and oxygen free radicals released from activated leucocytes contribute significantly to the organ dysfunction associated with cardiopulmonary bypass . Leucocyte depletion during extracorporeal circulation should reduce the release of these toxic compounds and thereby improve postbypass myocardial and pulmonary function . Recently , a leucocyte‐specific arterial line filter to achieve leucocyte depletion during clinical perfusion has become commercially available . The aim of this study , therefore , was to evaluate the influence of the leucocyte depleting arterial line filter on proteolytic enzyme release , oxygen free radical release and postbypass pulmonary and myocardial function in patients undergoing bypass surgery An important factor in the production of myocardial damage following cardiopulmonary bypass in the creation of oxygen derived free radicals . Few sources for these radicals have been identified but experimentally activated neutrophils are known to release free radical which contribute to myocyte necrosis . The aim of this pilot study was to identify whether , by depleting patients of leukocytes and particularly neutrophils on bypass , a better degree of myocardial protection could be observed using specific identifiers of myocardial damage . Ten patients undergoing urgent coronary artery bypass for unstable angina with impaired left ventricular function were leuko-depleted using a PALL medical leukocyte filter in the extra corporeal circulation together with leukocyte depletion of all transfused blood . A similar group of matched controls had only an arterial line filter without leukodepletion . All patients were operated by one surgeon using identical techniques of intermittent cross clamping and fibrillation at moderate hypothermia .  Full blood count , Glutathione , Troponin T and CPK/MB were measured before , during and at identified intervals up to 72 hour after bypass . Preliminary results show little change in the total leukocyte count but the Troponin T and CPK/MB values were lower in the filtered group than in the control group and an increased level of total Glutathione in the filter group showed that there was less oxi date d stress on the myocardium . Currently this filter is an expensive addition to bypass surgery but these preliminary results suggest that activated neutrophil depletion on bypass may be of benefit to patients with unstable angina , impending myocardial necrosis and low ejection fraction Fifty-four male patients were examined by an extensive battery of neuropsychological tests before and 1 and 6 months after coronary artery surgery . The patients were r and omized to one of three methods of extracorporeal circulation ( ECC ) : bubble oxygenation without an arterial line filter ( Group I , n = 17 ) , bubble oxygenation with an arterial filter ( Group II , n = 17 ) , or membrane oxygenation without an arterial filter ( Group III , n = 20 ) . The mean age was 59 ( range 44 - 69 ) years . At 1 month nine patients ( 17 % ) and at 6 months four patients ( 7 % ) had neuropsychological deficits ( reduction of 1 st and ard deviation in two or more tests ) . Postoperative intellectual dysfunction was found in groups I , II , and III at 1 and 6 months in 24 % and 12 % , 12 % and 6 % , and 15 % and 5 % , respectively . The differences between groups were not statistically significant . Significantly more patients in the membrane oxygenator group than in the bubble-oxygenator group without a filter performed better in the test for attention , visual scanning , and psychomotor speed and in the test for learning and memory at 1-month follow-up . In conclusion , there exists a risk of neuropsychological dysfunction after ECC , with improvement within the first 6 months , which is independent of the type of oxygenation and the use of arterial line filtration during ECC in this low-risk group STUDY OBJECTIVE To determine whether inclusion of a leukocyte specific filter into the extracorporeal circuit during aortocoronary bypass surgery alters postoperative cardiopulmonary function . DESIGN R and omized , double-blinded control trial . SETTING Tertiary care hospital . PATIENTS Convenience sampling of patients undergoing elective aortocoronary bypass between October 1992 and June 1993 . INTERVENTIONS A total of 32 patients were r and omized to a leukocyte specific filter ( n = 16 ) or to a st and ard blood filter ( n = 16 ) during the surgical procedure . MEASUREMENTS AND RESULTS White blood cell count in the st and ard filter group ( 12.2 + /- 3.6 10(9)/L ) was higher ( p = 0.047 ) than in the leukocyte filter group ( 9.9 + /- 2.6 10(9)/L ) at 4 h postoperatively but counts were similar ( p = 0.063 ) at 24 h ( 10.8 + /- 2.7 vs 8.9 + /- 2.6 10(9)/L , respectively ) . Leukocyte activation assessed by chemiluminescence was similar between groups at all measurement periods . We noted transient improvements ( p < 0.05 ) in intrapulmonary shunt ( 19 + /- 50 % vs 24 + /- 9 % ) and mean blood pressure ( 85 + /- 8 vs 76 + /- 9 mm Hg , respectively ) in the leukocyte filter group compared with the st and ard filter group , respectively . Otherwise there were no differences noted between groups . CONCLUSIONS Inclusion of a leukocyte filter during cardiopulmonary bypass caused transient cardiorespiratory improvement that was lost within 24 h and did not offer any significant clinical benefits In some patients , coronary artery bypass surgery induces postoperative organ dysfunction despite an apparently adequate revascularization and good haemodynamic performance . This complication may be caused by activation of the body ’s inflammatory systems on blood contact with large foreign surfaces in the extracorporeal circuit . Activated leucocytes may play an important role in organ damage , and it is conceivable that leucocyte removal by filtration may decrease the potential side-effects of cardiopulmonary bypass ( CPB ) . The aim of the present study was to investigate possible effects of leucocyte filtration during the whole CPB period in elective coronary artery bypass surgery  on biochemical and clinical parameters . Forty patients were r and omized to extracorporeal circulation using a leucocyte-depleting filter ( group L , n = 20 ) or to extracorporeal circulation with no leucocyte filter ( group C , n = 20 ) . In the leucocyte-depleted group , the mean total white blood cell counts increased from 6.3 ( 95 % confidence interval , 5.5 - 7.0 ) × 109/l to 7.0 ( 5.7 - 8.3 ) × 109/l during extracorporeal circulation and in the control group from 6.3 ( 5.2 - 7.3 ) × 109/l to 8.5 ( 7.2 - 9.8 ) × 109/l . The intergroup difference was not statistically significant ( p = 0.84 ) . A substantial increase in concentrations of interleukin-6 , myeloperoxidase and complement activation products were observed in both groups without statistically significant intergroup differences . It is concluded that the leucocyte-depletion filter did not cause a significant reduction of circulating white blood cells during CPB , and there were no significant differences between the groups with respect to the inflammatory markers studied BACKGROUND An increase of S100beta in serum during  cardiopulmonary by 
    Output:
    
Whereas conventional filtration has the definite effect of reducing neuropsychological deficit post-CPB , the results of studies using the leucocyte-depleting filter are less clear cut .