Cerebral functional changes following cardiac surgery: Neuropsychological and EEG assessment.
OBJECTIVE
Some form of organic and functional cerebral deficit may occur in up to one third of patients following cardiopulmonary bypass surgery. This study was designed to assess cerebral functional deficit in cardiac surgical patients.


METHODS
Neuropsychological and quantitative electroencephalographic (EEG) changes were assessed in 62 first time coronary artery bypass graft surgery patients before surgery and within 1 week and 2 months after surgery. Patients underwent surgery with a standard Hammersmith Hospital anaesthesia and hypothermic cardiopulmonary bypass (28 degrees C), using either bubble (Harvey 1700, n = 28) or membrane (Cobe CML, n = 34) oxygenators with arterial line filters (Pall 40 microm). Neuropsychological performance was assessed using a well established battery of ten tests. Four EEG relative power frequency bands; delta (1-3.5 Hz), theta (4-7.5 Hz), alpha (8-11.5 Hz), and beta (12-23 Hz), were determined using Fast Fourier Transformation (FFT).


RESULTS
Neuropsychological and EEG deficits were found in 48% of patients 1 week after surgery and in 34% 2 months after surgery. Post-operative deficits were not associated with duration of perfusion, type of oxygenator used in surgery or patient age. Neuropsychological and EEG deficits were associated 2 months after surgery, but not 1 week after surgery. Post-operative EEG deficit was associated with pre-operative deficit.


CONCLUSIONS
Cerebral functional deficit was found following CABG surgery using quantitative EEG and neuropsychological assessments. Patients who had neuropsychological deficit were also more likely to show EEG deficit. EEG deficit before and after surgery suggests vulnerability of patients with already compromised cerebral function to the effects of CPB procedure.
Toner
I
I
Department of Cardiothoracic Surgery, Royal Postgraduate Medical School and Hammersmith Hospital, London, UK.
Taylor
K M
KM
Newman
S
S
Smith
P L
PL
D000328:Adult; D000368:Aged; D001927:Brain Diseases / Q000209:etiology* / Q000473:pathology*; D002545:Brain Ischemia / Q000209:etiology / Q000473:pathology; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D003327:Coronary Disease / Q000503:physiopathology / Q000601:surgery; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D019954:Neurobehavioral Manifestations; D009483:Neuropsychological Tests; D011184:Postoperative Period; D011300:Preoperative Care; D011379:Prognosis; D012680:Sensitivity and Specificity; D013997:Time Factors