Tom Treasure

CEREBRAL CONSEQUENCES OF CARDIOPULMONARY BYPASS

55 patients undergoing coronary-artery bypass surgery (CABS) and a comparison group of 20 patients having thoracic or major vascular surgery were investigated preoperatively and 8 days and 8 weeks postoperatively for changes in neuropsychological status, psychiatric state, cerebral blood flow, and neurological signs, this last being assessed also at 24 h. Major persisting neurological changes were rare, but minor abnormalities were significantly more common after CABS than after thoracic or vascular surgery. Neuropsychological deficits were common at 8 days in both CABS and comparison groups, and in about a third of all patients persisted at 8 weeks. Cerebral blood flow was reduced at 8 days in some CABS patients, but this was not significant for the group. Pre-existing cerebrovascular disease was not predictive, but low perfusion pressure and long bypass time were associated with postoperative deficits.

Subjective reports of cognition in relation to assessed cognitive performance following coronary artery bypass surgery.

Evidence has accumulated to indicate that a proportion of patients who undergo coronary artery bypass surgery (CABS) do develop significant cognitive deficits. This study examines whether those patients who report cognitive deterioration after CABS do show cognitive changes as assessed by neuropsychological testing. The patients who considered that aspects of their cognitive function had deteriorated, were not found to have reduced functions as assessed on appropriate neuropsychological tests. When mood state was examined, it was found that those who report a deterioration in a particular cognitive function, tended to have significantly higher levels of depression as assessed by the Beck Depression Inventory and, to a lesser extent, have higher levels of state anxiety. These findings emphasise that subjective reports of cognitive function following CABS do not reflect actual changes in cognition but rather appear to be sensitive to mood state.

Acute neuropsychological consequences of coronary artery bypass surgery

This study examines a series of coronary artery bypass patients (CABS) for neuropsychological and regional cerebral blood flow (RCBF) changes at 8 days and 8 weeks post surgery. Seventy-three percent were found to have moderate or severe neuropsychological deficits at 8 days post operation and 37% at 8 weeks post surgery. A comparison group of major vascular and thoracic surgery patients was also found to have a significant proportion of neuropsychological deficit following surgery. The RCBF assessments indicated a significant drop in mean RCBF at 8 days post surgery in the coronary artery bypass group which did not persist to 8 weeks. The comparison group showed no changes in RCBF following surgery. The findings suggest different patterns of recovery and origins of the neuropsychological deficit in the two groups and emphasize the need for appropriate control groups in studies examining the cortical effects of extracorporeal circulation.

Cerebrovascular disease and functional outcome after coronary artery bypass surgery.

A series of patients undergoing coronary artery bypass surgery was studied prospectively to see if angiographic evidence of cerebrovascular disease proved predictive of the incidence of neuropsychological deficit 8 days or 8 weeks after surgery. In 47 patients, intravenous digital subtraction angiography was carried out preoperatively to assess the presence and severity of atheromatous changes in the carotid arteries; 51% had evidence of vessel wall disease and 17% had stenosis of at least one carotid artery in the neck, although only one patient had severe narrowing. Overall, 77% of these 47 patients showed a neuropsychological deficit as defined by a significantly reduced score in at least two of 10 tests administered 8 days after surgery. Eight weeks after surgery 36% still showed a deficit. The incidence of neuropsychological deficit was not significantly greater among those patients with angiographically visible carotid artery disease. The mechanism of surgery-related cognitive impairment is briefly discussed in the light of these findings.

Pulmonary Metastasectomy: A Common Practice Based on Weak Evidence

The resection of secondary metastases from the lungs is a wide-spread surgical practice. Patients are referred from coloproctology teams to thoracic surgeons specifically for this surgery. What is the expected benefit? I have explored the rationale and searched the literature in order to present these patients with a well-informed opinion for their consideration. I find only weak evidence based on uncontrolled retrospective series which have been interpreted as showing a survival benefit. This has been extrapolated to policy and practice that do not stand up to scrutiny. The practice has never been subjected to randomised trial and I will argue that the present evidence is insufficient to justify the uncontrolled use of an intervention with inescapable short-term morbidity, permanent loss of function, and major cost implications. I propose ways in which the evidence may be improved, including a trial in the areas of most uncertainty.

The Persistence of Neuropsychological Deficits Twelve Months After Coronary Artery Bypass Surgery

That some cardiac surgery results in brain damage has been known for some time and has been demonstrated in pathological findings [1, 2]. Much current attention has focused specifically on coronary artery bypass surgery (CABS) which has seen a dramatic increase in recent years. The techniques and time on extracorporeal circulation have, however, changed considerably over the years and studies performed some time ago may not provide an accurate picture of the frequency of deficits with current surgical practice [3].

Cerebral blood flow during cardiopulmonary bypass

In a study of the cerebral consequences of cardiopulmonary bypass (CPB), we have assessed cerebral blood flow (CBF) by intra-arterial Xenon 133 clearance, utilising a Novocerebrograph 10a, before, during and immediately following CPB. All patients (n = 51), under the care of a single surgical team underwent elective coronary revascularisation using a standardised anaesthetic and surgical protocol. CBF, measured as the initial slope index (ISI), fell significantly from before (median 22.5) to on bypass (median 20) (Wilcoxon P less than 0.005) and was significantly increased in the immediate post-bypass period (median 28) compared with pre-bypass (Wilcoxon P less than 0.001). Scattergrams reveal CBF to be independent of arterial pressure (BP) but show an important relationship between arterial PaCO2 and CBF. The correlations between PaCO2 and CBF prior to bypass (r = 0.46 P less than 0.005) and post-bypass (r = 0.46 P less than 0.001) are very similar, whilst on bypass, the correlation, although remaining significant, is reduced (r = 0.31 P less than 0.02). The median values for arterial PaCO2 are low throughout the study (pre-bypass median 33 mmHg, on bypass median 28 mm Hg and post-bypass median 36 mm Hg). The maintenance of PaCO2 within the normal range of 35-45 mm Hg may minimise the risk of low CBF due to hypocarbia which could theoretically be harmful in patients known to be at risk of both short term and long term cerebral dysfunction.

Appendicectomy: who performs it, when and how?

A comparative review of changing patterns between 1997 and 2002 of who performs appendicectomy and a snapshot of the surgical approaches in use. It also indicates the stage at which competency in appendicectomy may be achieved by contemporary trainees in surgery and anaesthesia.

REPORTS OF COGNITIVE CHANGE, MOOD STATE AND ASSESSED COGNITION FOLLOWING CORONARY-ARTERY BYPASS-SURGERY

The impact of coronary artery bypass surgery (CABS) on the amelioration of angina and breathlessness has been dramatic with approximately 90% of patients reporting symptomatic improvement. In recent years this success has been clouded by studies which have indicated a deterioration in cognitive performance with formal neuropsychological testing performed preoperatively and postoperatively [1, 2]. Studies investigating neuropsychological changes have confirmed that approximately 35% of patients show deficits 8 weeks post surgery [31], still detectable in 33% at one year [4].