QEEG and neuropsychological profiles of patients prior to undergoing cardiopulmonary bypass surgical procedures

Monitoring the Electroencephalogram During Bypass Procedures

Electroencephalographic monitoring has been performed since the early days of cardiopulmonary bypass. Despite this long experience, the technology has never been widely used for cardiac operations. This review examines the reasons for the limited use and describes technological advances that may alter this pattern.

Anesthetic technique (sufentanil versus ketamine plus midazolam) and quantitative electroencephalographic changes after cardiac surgery

OBJECTIVES

Cardiac surgery involving cardiopulmonary bypass is associated with neurologic deterioration. Several interventions, including anesthetic techniques, have been designed to limit ischemic brain damage and have been evaluated in animals. Markers of neurologic injury may facilitate the assessment of these interventions in humans.

DESIGN

A blinded randomized prospective study comparing 2 anesthetic techniques (one sufentanil-based, the other ketamine and midazolam-based) in patients undergoing cardiac surgery. Quantitative electroencephalography was used to detect postoperative neurologic injury.

SETTING

Major teaching hospital.

PARTICIPANTS

Forty-two patients aged 18 to 70 years undergoing cardiac surgery.

INTERVENTIONS

Patients were anesthetized with either a sufentanil-based or a ketamine and midazolam-based technique for cardiac surgery with cardiopulmonary bypass. Quantitative electroencephalography was performed preoperatively as well as 5 to 6 days postoperatively.

MEASUREMENTS AND MAIN RESULTS

Quantitative electroencephalography outcome did not differ (p > 0.05) between the 2 groups. It showed significant deterioration between preoperative and postoperative assessments with a decrease in faster and an increase in slower frequencies. In addition, the alpha attenuation index decreased. This may reflect a decrease in alertness. Both the intergroup comparisons and the assessment of individual changes failed to reveal significant differences between the anesthetic techniques. The adjuvant use of isoflurane correlated with less deterioration of quantitative electroencephalographic variables.

CONCLUSIONS

The use of either sufentanil-based or ketamine and midazolam-based anesthetic techniques for cardiac surgery with cardiopulmonary bypass had no effects on a marker of postoperative neurologic injury (ie, quantitative electroencephalography).

QEEG changes during cardiopulmonary bypass: relationship to postoperative neuropsychological function

The relationship of changes in intraoperative QEEG and postoperative cognitive function was studied in 32 patients undergoing cardiac surgical procedures requiring cardiopulmonary bypass (CPB). All patients were anesthetized with a high dose narcotic technique in which CPB was carried out using moderate hypothermia. EEG recorded continuously throughout each procedure was analyzed using the neurometric technique. Neuropsychological (NP) evaluations were administered to all patients before, 1 week and 2-3 months postoperatively. A decrement in postoperative performance of 2 standard deviations in two or more tests from preoperative testing was defined as a new cognitive deficit. Of the patients studied, 40.6% demonstrated a new postoperative cognitive deficit at 1 week. At 2-3 months postoperatively, 28.1% continued to show a cognitive deficit. Discriminant analysis of the QEEG as a function of NP performance was calculated at select times during the surgical procedure. QEEG prediction of NP performance was just above chance at the 1 week comparison but excellent for the 2-3 month comparisons. This study suggests that with appropriate monitoring protocols, intraoperative QEEG may predict cognitive dysfunction experienced by patients 2-3 months postoperatively.

QEEG and neuropsychological profiles of patients after undergoing cardiopulmonary bypass surgical procedures

One week after surgery neuropsychological (NP) deficits were quite common, occurring in 40.6% of the patients, with QEEG abnormality developing or increasing in the majority of patients. This change in the QEEG was an accurate predictor of NP performance 1 week after surgery. Two to three months after surgery evidence of continued NP performance deficits were still present in 28.1% of the patients. Preoperative versus one week postoperative QEEG change showed higher levels of sensitivity and specificity for predicting neuropsychological performance 3 months after CPB surgery than did preoperative versus one week postoperative NP performance. The mean values of specificity plus sensitivity were 74.5% for NP performance and 89.1% for the QEEG. These high levels of sensitivity and specificity for QEEG change for predicting postoperative cognitive function may justify the utility of performing these evaluations in the general CPB surgical population. In addition, this evidence supports the need to study the role of intraoperative QEEG monitoring to determine when QEEG change occurs so that possible remediational measures can be taken as soon as possible.