A prospective clinical study of cerebral microemboli and neuropsychological outcome comparing vent-line and auto-venting arterial line filters: both filters are equally safe.

INTRODUCTION: Microemboli are the main implicated cause of neuropsychological (NP) impairment after cardiac surgery. This prospective clinical trial compared the effect of an auto-venting arterial line filter on intraoperative cerebral microemboli and NP outcome compared to an arterial line filter with a vent line, in patients undergoing elective coronary artery bypass graft (CABG) surgery. METHODS: One hundred and ten patients received either an Avecor Affinity (n =73) or Pall AV-6 (n =37) control filter. Cerebral microemboli during cardiopulmonary bypass were recorded by transcranial Doppler monitoring of the right middle cerebral artery. Evidence of cerebral impairment was obtained by comparing patients' performance in a NP test battery (nine tests) administered 6-8 weeks postoperatively with their preoperative scores. RESULTS: During cardiopulmonary bypass, the median number and range of microemboli were 67 (5-846) and 55 (2-773) for the Avecor and AV-6 groups, respectively (p = 0.47). There was no difference in NP outcome. CONCLUSION: There is no difference in the filtering ability of vent-line and auto-vent filters as assessed by cerebral microemboli. This, together with the similar NP outcome, suggests that both types of filter are equally safe for clinical use.

Leucocyte-depleting arterial line filtration does not reduce myocardial injury assessed by Troponin T during routine coronary artery bypass grafting using crossclamp fibrillation.

INTRODUCTION: Leucocyte filtration can reduce inflammation and end-organ damage. The aim of this study was to test the cardioprotective effect of systemic leucocyte filtration during cardiopulmonary bypass (CPB) for coronary revascularization. METHODS: Sixty patients scheduled for elective coronary artery bypass grafting were prospectively randomised to receive either a test leucocyte-depleting (LD) filter or a control standard arterial line filter in the CPB circuit. Myocardial injury was determined by serum Troponin T concentration up to 72 h postoperatively. In addition, perioperative neutrophil counts, serum elastase and electrocardio-grams (ECGs) were evaluated. RESULTS: There was a peak of Troponin T release at 6 h in both groups. There was no difference between LD or control group Troponin T at any time point. No difference in neutrophil count was found. A greater rise in neutrophil elastase occurred in the LD group during CPB and 10 min post CPB (376 and 496 versus 108 and 228 mcg/L, p<0.001). CONCLUSIONS: LD arterial line filters did not confer any cardioprotective effect as measured by Troponin T in elective coronary revascularization cases.

The effect of leucocyte-depleting arterial line filters on cerebral microemboli and neuropsychological outcome following coronary artery bypass surgery.

OBJECTIVES: A randomised clinical trial sought evidence as to whether leucocyte-depleting (LD) arterial line filters added a further degree of neuroprotection in patients undergoing elective coronary artery bypass graft (CABG) surgery. METHODS: One hundred and ninety-two patients were randomised to the use of a Pall Leukoguard-6 LD filter or either an Avecor Affinity or Pall Autovent-6 control filter. Cerebral microemboli during surgery were recorded by transcranial Doppler (TCD) monitor over the right middle cerebral artery. Evidence of cerebral impairment was obtained by comparing patients' performance in a neuropsychological (NP) test battery (nine tests) administered 6-8 weeks post-operatively with their pre-operative scores. RESULTS: The groups proved well balanced in pre-operative variables. During cardiopulmonary bypass (CPB) the median number and range of microemboli was 15 (3-180) in the LD group compared to 67 (5-846) and 55 (2-773) for the Avecor and AV6 groups, respectively (P<0.0001). One hundred and sixty-two patients completed all the NP tests. The LD group showed better post-operative performance in all but one of the nine tests although the difference in a total change score just failed to reach significance (P=0.07 one-tailed t-test). CONCLUSIONS: LD filtration during CABG reduced the number of cerebral microemboli recorded by TCD and showed a strong trend towards improving NP performance post-operatively. These findings suggest that the use of such filters in CABG surgery may offer increased neuroprotection.

Clinical trial of the neuroprotectant clomethiazole in coronary artery bypass graft surgery: a randomized controlled trial.

BACKGROUND: The neuroprotective property of clomethiazole has been demonstrated in several animal models of global and focal brain ischemia. In this study the authors investigated the effect of clomethiazole on cerebral outcome in patients undergoing coronary artery bypass surgery. METHODS: Two hundred forty-five patients scheduled for coronary artery bypass surgery were recruited at two centers and prospectively randomized to clomethiazole edisilate (0.8%), 225 ml (1.8 mg) loading dose followed by a maintenance dose of 100 ml/h (0.8 mg/h) during surgery, or 0.9% NaCl (placebo) in a double-blind trial. Coronary artery grafting was completed during moderate hypothermic (28-32 degrees C) cardiopulmonary bypass. Plasma clomethiazole was measured at several intervals during and up to 24 h after the end of infusion. A battery of eight neuropsychological tests was administered preoperatively and repeated 4-7 weeks after surgery. Analysis of the change in neuropsychological test scores from baseline was used to determine the effect of treatment. RESULTS: Neuropsychological assessments were completed in 219 patients (110 clomethiazole; 109 placebo). The mean plasma concentration of clomethiazole during surgery was 66.2 microm. There was no difference between the clomethiazole and placebo group in the postoperative change in neuropsychological test scores. CONCLUSION: Clomethiazole did not improve cerebral outcome following coronary artery bypass surgery.

Coronary-artery bypass surgery and the brain: persisting concerns.

Mortality after coronary-artery bypass surgery (CABS) has fallen steadily over recent years. Concern remains, however, about the effect of this surgery on the brain. The problem of brain damage after CABS is multifactorial, involving microembolism, disturbed perfusion, metabolic derangement, and inflammatory responses. Microemboli numbers have been linked to the likelihood of neuropsychological deterioration after surgery. Risk factors for cerebral changes after CABS include older age, gender, neurological disease, diabetes, and calcification of the aorta. These risk factors are important because, in comparison with the early 1990s, patients undergoing CABS are now older and tend to have a greater number of comorbid conditions. Changes in surgical technique, such as the introduction of arterial-line filters and membrane oxygenators, have led to a reduction of both microemboli and neuropsychological disturbance. However, the problem persists, prompting further studies on surgical technique and neuroprotective strategies.