Cognitive dysfunction after coronary artery bypass surgery: a case-controlled study.

Twenty-two patients screened from a sample of 391 having coronary artery bypass grafting (CABG) showed significant declines on the Mini-Mental State Examination (MMSE) administered preoperatively and four days postoperatively. The MMSE is a 30-point cognitive function screening instrument for dementia and delirium. These patients were compared with 22 matched control subjects who exhibited intact cognitive function postoperatively. The study assessed the association between postoperative cognitive dysfunction and socioeconomic status, potential effects of selected surgical/anesthetic factors, and preoperative anxiety and depression (Zung Anxiety and Center for Epidemiologic Studies-Depression [CES-D] self-rating scales). The results indicate that a higher preoperative level of depression reported on the CES-D (mean score of study patients 22.1 versus 12.7 for controls) is significantly associated with the development of postoperative cognitive dysfunction (P less than .01). The educational and occupational levels of study patients were significantly below those of controls (P less than .01, P less than .02). Occurrence of a postoperative complication was the only surgical/anesthetic factor found to be significantly associated with cognitive dysfunction (P less than .01). These findings suggest that preoperative depression significantly increases the risk for immediate postoperative cognitive dysfunction, and that lower socioeconomic status may confer greater risk for postoperative cognitive morbidity.

Computer-assisted continuous infusions of fentanyl during cardiac anesthesia: comparison with a manual method.

The design and implementation of a computer-assisted continuous infusion (CACI) system to rapidly attain and maintain a constant plasma fentanyl concentration (PFC), as well as a CACI system that allowed the anesthesiologist to change the plasma level of fentanyl during cardiac anesthesia, were developed. In 30 patients (three groups of 10 patients each) these two automated methods of fentanyl infusion were compared with a manual fentanyl administration method. There was excellent agreement in the measured/predicted PFC ratios with the CACI stable fentanyl level system (ratio = 0.99, n = 91) and in the CACI variable fentanyl level system (ratio = 1.08, n = 79). The stable fentanyl level group of patients received significantly more (P less than 0.05) fentanyl than did the other groups. The CACI variable fentanyl level group of patients had greater hemodynamic stability, required significantly (P less than 0.05) fewer adjuvant drug interventions and experienced significantly (P less than 0.05) fewer hypotensive and hypertensive episodes than the manual, bolus fentanyl (control) group. These data show that a computer-assisted automated infusion of fentanyl is safe and as good as manual methods. CACI has greater potential as a new method of intravenous anesthesia administration.

Cardiovascular effects of esmolol in anesthetized humans.

We studied the cardiovascular effects of esmolol, a newly synthesized beta-adrenocepter antagonist, in anesthetized humans. Forty patients (four groups of 10 each) with ischemic heart disease and normal ventricular function were anesthetized with diazepam, pancuronium, and N2O in O2. Esmolol was given by continuous infusion in cumulative doses of 1100 micrograms/kg (group 1), 2000 micrograms/kg (group 2), and 2700 micrograms/kg (group 3); a control group received no esmolol. Infusion of esmolol was begun 3 min prior to and ended 4 min after tracheal intubation. All three doses of esmolol significantly (P less than 0.001) attenuated the heart rate responses to intubation. Rate-pressure products were significantly (P less than 0.001) lower in esmolol-treated patients than in controls after intubation, but ST-segment changes compatible with ischemia occurred in one patient in each group. Increases in heart rate were associated with significant increases in plasma norepinephrine levels (r = 0.45, P = 0.02) in the control group, but not in esmolol-treated patients, a demonstration that esmolol antagonizes the beta-adrenergic effects of norepinephrine. The effect of esmolol on heart rate was absent 5 min after cessation of infusion, and plasma levels of esmolol were undetectable in 26 of 30 treated patients 15 min after the termination of esmolol infusion. Esmolol has a rapid onset and short duration of effect. It can be used safely during anesthesia in patients with normal ventricular function to attenuate cardiac response to sympathetic stimulation.

Cognitive function after coronary bypass surgery: effect of decreased cerebral blood flow.

The effect of regional cerebral blood flow during coronary bypass surgery on performance on the Mini-Mental State Examination was studied in 14 patients. No association between lowered regional cerebral blood flow and cognitive scores was found.

Factors and their influence on regional cerebral blood flow during nonpulsatile cardiopulmonary bypass.

In this study we examined the relationship of regional cerebral blood flow (CBF) to mean arterial pressure, systemic blood flow, partial pressure of arterial carbon dioxide (PaCO2), nasopharyngeal temperature, and hemoglobin during hypothermic nonpulsatile cardiopulmonary bypass (CPB). Regional CBF was determined by clearance of xenon 133 in 67 patients undergoing coronary bypass grafting procedures. There was a significant decrease in regional CBF (55% decrease) during CPB, with nasopharyngeal temperature and PaCO2 being the only two significant factors (p less than 0.05). In a subgroup of 10 patients, variation of pump flow between 1.0 and 2.0 L/min/m2 did not significantly affect regional CBF. We conclude that cerebral autoregulation is retained during hypothermic CPB. Under the usual conditions of CPB, variations in flow and pressure are not associated with important physiological or detrimental clinical affects.