A Quantitative EEG Method for Detecting Post Clamp Changes During Carotid Endarterectomy

Cerebral hemodynamic changes and electroencephalography during carotid endarterectomy

Biochemical markers of cerebral damage

Invited commentary

Arterial spin labeling (ASL) is a non-invasive technique for measuring cerebral perfusion. Its accuracy is affected by the arterial transit time. This study aimed to (1) evaluate the accuracy of ASL in measuring the cerebral perfusion of patients who underwent carotid endarterectomy (CEA) and (2) determine a better postlabeling delay (PLD) for pre- and postoperative perfusion imaging between 1.5 and 2.0 s. A total of 24 patients scheduled for CEA due to severe carotid stenosis were included in this study. All patients underwent ASL with two PLDs (1.5 and 2.0 s) and computed tomography perfusion (CTP) before and after surgery. Cerebral blood flow (CBF) values were measured on the registered CBF images of ASL and CTP. The correlation in measuring perioperative relative CBF (rCBF) and difference ratio of CBF (DRCBF) between ASL with PLD of 1.5 s (ASL1.5) or 2.0 s (ASL2.0) and CTP were also determined. There were no significant statistical differences in preoperative rCBF measurements between ASL1.5 and CTP (p = 0.17) and between ASL2.0 and CTP (p = 0.42). Similarly, no significant differences were found in rCBF between ASL1.5 and CTP (p = 0.59) and between ASL2.0 and CTP (p = 0.93) after CEA. The DRCBF measured by CTP was found to be marginally lower than that measured by ASL2.0_1.5 (p = 0.06) and significantly lower than that measured by ASL1.5_1.5 (p = 0.01), ASL2.0_2.0 (p = 0.03), and ASL1.5_2.0 (p = 0.007). There was a strong correlation in measuring perioperative rCBF and DRCBF between ASL and CTP (r = 0.67-0.85, p < 0.001). Using CTP as the reference standard, smaller bias can be achieved in measuring rCBF by ASL2.0 (-0.02) than ASL1.5 (-0.07) before CEA. In addition, the same bias (0.03) was obtained by ASL2.0 and ASL1.5 after CEA. The bias of ASL2.0_2.0 (0.31) and ASL2.0_1.5 (0.32) on DRCBF measurement was similar, and both were smaller than that of ASL1.5_1.5 (0.60) and ASL1.5_2.0 (0.60). Strong correlation can be found in assessing perioperative cerebral perfusion between ASL and CTP. During perioperative ASL imaging, the PLD of 2.0 s is better than 1.5 s for preoperative scan, and both 1.5 and 2.0 s are suitable for postoperative scan.

Quantitative EEG changes due to cerebral vasoconstriction. Indomethacin versus hyperventilation-induced reduction in cerebral blood flow in normal subjects

This study was designed to determine whether the preoperative, baseline electroencephalogram (EEG) can be used for intraoperative decision making during carotid endarterectomy, and to identify circumstances where the EEG can be eliminated. The charts of all patients undergoing carotid endartectomy at the authors' institution from June 1991 to May 1995 were reviewed to identify those patients that had adequate pre- and intraoperative EEG monitoring. EEGs during 331 carotid endartectomies in 303 patients were coded without knowledge of outcome; primary and secondary endpoints were EEG changes with clamping and clinical outcome, respectively. The incidence of mortality and major neurological morbidity was 1.8%. Baseline-EEGs were abnormal in 105 patients (32%). Whereas baseline-EEG changes were highly predictive of EEG changes after anesthetic induction (P < .0001), they were not predictive of EEG changes with clamping or of clinical outcome. Prior stroke (CVA) predicted abnormal baseline-EEGs (P < .0001) and abnormal post-anesthetic EEGs (P < .0001) but did not predict changes with clamping or perioperative CVA. EEG changes with clamping occurred during 18% of operations; such changes were predicted only by contralateral occlusion (P < .0016) and EEG changes during a prior contralateral carotid endartectomy (P < .0001). The only variable that predicted an adverse neurological outcome was the presence of contralateral occlusion, which increased the likelihood of a perioperative neurological event seven-fold (P = .0038). Clinical outcomes in the 57 of 105 patients with abnormal baseline-EEGs and the 49 of 83 with prior CVA who were shunted were not different from those who were not. baseline-EEG is not of value for the prediction of adverse events during carotid endartectomy and can be eliminated. Because contralateral occlusion is highly predictive of changes with clamping, and patients undergoing a second carotid endartectomy will usually manifest EEG changes identical to those at the first, operative EEG monitoring can also be eliminated from both these circumstances. Finally, prior stroke does not lead to a higher incidence of clamp-induced EEG changes, and thus is not an indication for shunting in and of itself.

Regarding "Carotid endarterectomy with routine electroencephalography and selective shunting: influence of contralateral internal carotid artery occlusion and utility in prevention of perioperative strokes".

To determine whether 1-day postoperative hospitalization after carotid endarterectomy is safe and the degree to which this can be achieved. Consecutive sample series of all carotid endarterectomies performed by a single surgical group. A single tertiary-care hospital. All who underwent carotid endarterectomy. Patients with procedures combined with coronary revascularization and patients undergoing the first part of a staged bilateral carotid endarterectomy performed in 1 hospitalization were excluded. In December 1993, a fast-track protocol was initiated, aiming for a 1-day stay after carotid endarterectomy without admission to an intensive care unit (ICU). Before this date, postoperative care included obligatory monitoring for at least 1 night in an ICU. Length of stay, admission to and stay in the ICU, complications, and hospital readmission rate. Over a 21-month period, 152 patients had 163 carotid endarterectomies. Of these, 124 were elective and 39 urgent (patients with a critical stenosis). Indications were stroke (n = 14 [8.6%]), transient ischemic attack (n = 50 [30.7%]), amaurosis fugax (n = 36 [22.1%]), and asymptomatic stenosis (n = 63 [38.7%]). General anesthesia was used for 159 procedures, cervical block for 4. Mean operation time was 2.6 hours. Postoperative stay was 1 day for 82 procedures (50%), 2 days for 49 procedures (30%), 3 days for 12 procedures (7%), and longer for 20 procedures (12%). In the last half of the study, 61% of patients (50/82) were discharged on postoperative day 1 and 87% (71/82) by postoperative day 2. One hundred three patients went to a surgical floor postoperatively. Overall, 60 patients went to the ICU, but only 18 (22%) of the last 82 procedures required ICU admission. The total stay averaged 3.8 days. Twenty-one patients (13%) experienced complications, including 3 deaths within 30 days and 5 neurological deficits. There were 14 early readmissions, but none was attributable to discharge on the first or second postoperative day. Early discharge home after carotid endarterectomy is safe and efficacious, and obligatory admission to an ICU is not necessary. At least 60% of patients who undergo carotid endarterectomy can have a postoperative stay of 1 day, and more than 80% can be discharged by postoperative day 2. A short postoperative stay is not associated with a significant risk of readmission for complications.

Background: Patients undergoing carotid endarterectomy (CEA) may suffer from cerebral hypoperfusion during the carotid cross-clamping. Near-infrared spectroscopy cerebral oximetry (NIRS) is a non-invasive method of regional cerebral oxygen saturation measurement reflecting changes in cerebral blood flow during CEA. The main goal of the study was to evaluate the accuracy of the NIRS in detecting cerebral hypoperfusion during CEA under regional anesthesia (RA) and compare it with awake neurological testing. Patients and methods: A prospective observational study of 28 patients that underwent CEA in RA and manifested neurologic deficits, and 28 consecutive controls from a tertiary and referral center, was performed. All patients were monitored with NIRS cerebral oximetry and awake testing as the control technique. Subsequently, operating characteristic curve and Cohen's kappa coefficient were determined to evaluate the reliability of the monitoring test. Results: NIRS presented a sensitivity of 27.3% and a specificity of 89.3% in comparison to awake testing. Receiver operating characteristic (ROC) curve analysis demonstrated that a decrease of at least 20% in cerebral oxygen saturation is the best threshold to infer cerebral hypoperfusion. However, the respective area under the curve (AUROC) was 0.606 (95% CI: 0.456-0.756, P=0.178) with a calculated Cohen's kappa of 0.179, P=0.093. Regarding 30-days outcomes, only awake testing has shown significant associations with stroke and postoperative complications (P=0.043 and P=0.05), which were higher in patients with post-clamping neurologic deficits. Conclusions: NIRS demonstrated a reduced discriminative capacity for critical cerebral hypoperfusion, and does not seem to add substantial clinical benefits to the awake test.

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Quantitative electroencephalography data are helpful to predict outcomes of cerebral infarction patients. The study was performed to evaluate the value of brain symmetry index by quantitative electroencephalography in predicting 3-month mortality of large hemispheric infarction. We studied a prospective, consecutive series of patients with large supratentorial cerebral infarction confirmed within 3 days from the onset in 2 intensive care units from August 2017 to February 2020. The electroencephalography was recorded once admission. The brain symmetry index (BSI) which is divided into BSIfast and BSIslow were calculated for each electrodes pair. The outcome was mortality at 3 months after the onset. A total of 38 patients were included. The subjects were divided into the mortality group (15 patients) and survival group (23 patients). Of the BSIfast and BSIslow at each electrodes pair, higher BSIfastC3-C4, higher BSIslowC3-C4, and higher BSIslowO1-O2 were noticed in the mortality group than that in the survival group at 3 months (P = .001; P = .010; P = .009). Multivariable analysis indicated that BSIfastC3-C4 was an independent predictor of 3-month mortality (odds ratio = 1.059, 95%CI 1.003, 1.119, P = .039). BSIfastC3-C4 could significant predict 3-month mortality (area under curve = 0.805, P = .005). And when we combined BSIfastC3-C4, Glasgow Coma Scale and infarct volume together to predict the 3-month mortality, the predicted value increased (area under curve = 0.840, P = .002). BSIfastC3-C4 could independently predict the 3-month mortality of large hemispheric infarction. The combination marker which includes Glasgow Coma Scale, infarct volume, and BSIfastC3-C4 has a better diagnostic value. Further clinical trials with a large sample size are still needed.