Brain Oxygen Supply Parameters in the Risk Assessment of Cerebral Complications During Carotid Endarterectomy

Cerebrovascular dysregulation and postoperative cognitive alterations after carotid endarterectomy

There are controversial data about the effect of carotid endarterectomy regarding postoperative cognitive function. Our aim was to analyze the effect of cerebral tissue saturation monitored by near-infrared spectroscopy (NIRS) on cognitive function. Perioperative data of 103 asymptomatic patients undergoing elective carotid surgery under general anesthesia were analyzed. Preoperatively and 3 months after the operation, MMSE (Mini Mental State Examination) and MoCA (Montreal Cognitive Assessment) tests were conducted. For cerebral monitoring, NIRS was used, and the lowest rSO2 value and the degree of desaturation were calculated. Cognitive changes were defined as one standard deviation change from the preoperative test scores, defined as postoperative neurocognitive decline (PNCD) and cognitive improvement (POCI). PNCD was found in 37 patients (35.92%), and POCI was found in 18 patients (17.47%). Female gender, patients with diabetes, and the degree of desaturation were independently associated with PNCD. The degree of desaturation during the cross-clamp period negatively correlated with the change in the MoCA scores (R =  - 0.707, p = 0.001). The 15.5% desaturation ratio had 86.5% sensitivity and 78.8% specificity for discrimination. For POCI, a desaturation of less than 12.65% had 72.2% sensitivity and 67.1% specificity. POCI was associated with lower preoperative MOCA scores and a lower degree of desaturation. We found a significant relation between the change of postoperative cognitive function proven by the MoCA test and cerebral tissue saturation during the clamping period in patients undergoing carotid endarterectomy.

Non-Invasive Tools in Perioperative Stroke Risk Assessment for Asymptomatic Carotid Artery Stenosis with a Focus on the Circle of Willis

This review aims to explore advancements in perioperative ischemic stroke risk estimation for asymptomatic patients with significant carotid artery stenosis, focusing on Circle of Willis (CoW) morphology based on the CTA or MR diagnostic imaging in the current preoperative diagnostic algorithm. Functional transcranial Doppler (fTCD), near-infrared spectroscopy (NIRS), and optical coherence tomography angiography (OCTA) are discussed in the context of evaluating cerebrovascular reserve capacity and collateral vascular systems, particularly the CoW. These non-invasive diagnostic tools provide additional valuable insights into the cerebral perfusion status. They support biomedical modeling as the gold standard for the prediction of the potential impact of carotid artery stenosis on the hemodynamic changes of cerebral perfusion. Intraoperative risk assessment strategies, including selective shunting, are explored with a focus on CoW variations and their implications for perioperative ischemic stroke and cognitive function decline. By synthesizing these insights, this review underscores the potential of non-invasive diagnostic methods to support clinical decision making and improve asymptomatic patient outcomes by reducing the risk of perioperative ischemic neurological events and preventing further cognitive decline.

The intracranial effects of flow reversal during transcarotid artery revascularization

Background

This study aimed to assess intraoperative cerebral hemodynamic responses and embolic events during transcarotid artery revascularization via transcranial Doppler, near-infrared spectroscopy, and bispectral index monitoring.

Methods

Twelve patients (7 males, 5 females; mean age: 72.8±9.0 years; range, 63 to 91 years) undergoing transcarotid artery revascularization with simultaneous transcranial Doppler, near-infrared spectroscopy, and bispectral index monitoring were analyzed in this retrospective study between September 2017 and December 2019. The mean flow velocity and pulsatility index of the middle cerebral artery, alongside near-infrared spectroscopy and bispectral index values, before flow reversal, during flow reversal, and after flow reversal phases were investigated. The presence and frequency of high-intensity transient signals were recorded to evaluate embolic incidents.

Results

Significant reductions in middle cerebral artery mean flow velocity were noted during flow reversal (40.58±10.57 cm/sec to 20.58±14.34 cm/sec, p=0.0004), which subsequently returned to and exceeded baseline values after flow reversal cessation (53.33±17.69 cm/sec, p=0.0005). Near-infrared spectroscopy (71±4.4% to 66±6.2%) and bispectral index (45.71±8.5 to 40.14±8.1) values mirrored these hemodynamic changes, with notable decreases during flow reversal, and recoveries after flow reversal. The highest concentration of high-intensity transient signals was observed during stent deployment, signifying a critical embolic phase. No perioperative neurological complications or other significant adverse events were documented.

Conclusion

Transcranial Doppler, near-infrared spectroscopy, and bispectral index effectively monitor cerebral hemodynamics and embolic potential during transcarotid artery revascularization, providing real-time data crucial for optimizing perioperative management. These findings underscore the clinical value of multimodal monitoring in improving patient outcomes in transcarotid artery revascularization procedures.

The risk factors of postoperative cognitive dysfunction in patients undergoing carotid endarterectomy: an updated meta-analysis

OBJECTIVE

The purpose of the current meta-analysis was to determine the incidence and risk factors to provide a scientific basis for prevention and treatment of postoperative cognitive dysfunction (POCD) after carotid endarterectomy (CEA).

METHODS

Relevant articles published before October 2022 were searched from Pubmed/MEDLINE, Cochrane and Embase databases. The outcomes were the incidence and risk factors for POCD. A random-effects model was applied to estimate the overall odds ratios (ORs) and mean differences (MDs) for all risk factors through STATA 14.0 and RevMan 5.4. The quality of eligible studies was evaluated by Newcastle-Ottawa Scale (NOS) as previously described.

RESULTS

A total of 22 articles involving 3459 CEA patients were finally identified. The weighted mean incidence of POCD was 19% (95% confidence intervals (95% CI) 0.16-0.24, P < 0.001). Of the 16 identified risk factors, hyperperfusion (OR: 0.54, 95% CI 0.41-0.71) and degree of internal carotid artery (ICA) stenosis (OR: 5.06, 95% CI 0.86-9.27) were the potential risk factors of POCD, whereas patients taking statins preoperative had a lower risk of POCD (OR: 0.54, 95% CI 0.41-0.71). Subgroup analysis revealed that the risk of POCD at 1 month after CEA was higher in patients with diabetes (OR: 1.70, 95% CI 1.07-2.71).

CONCLUSION

The risk factors of POCD were hyperperfusion and degree of ICA stenosis, while diabetes could significantly increase the incidence of POCD at 1 month after surgery. Additionally, preoperative statin use could be a protective factor for POCD following CEA.

The influence of gender on 30-day adverse clinical outcomes in patients undergoing carotid surgery

BACKGROUND

We aimed to further evaluate sex differences of perioperative and 30-day complications after carotid surgery in patients with both asymptomatic and symptomatic carotid artery stenosis.

METHODS

This was a single-center prospective cohort study including 2013 consecutive patients, who were treated surgically due to extracranial carotid artery stenosis and prospectively followed. Patients who underwent carotid artery stenting and who were treated conservatively were excluded. The primary endpoints for this study were hospital stroke/transitory ischemic attack (TIA) and overall survival rates. Secondary outcomes included all other hospital adverse events, 30-day stroke/TIA, and 30-day mortality rates.

RESULTS

Hospital mortality was higher in female patients with symptomatic carotid stenosis (3% vs. 0.5%, P=0.018). Bleeding requiring re-intervention occurred more often in female patients with both asymptomatic (1.5% vs. 0.4%, P=0.045) and symptomatic carotid stenosis (2.4% vs. 0.2%, P=0.022). 30-day stroke/TIA and mortality rates were higher in female patients with both asymptomatic (stroke/TIA 4.4% vs. 2.5%, P=0.041; mortality 3.3% vs. 1.6%, P=0.046) and symptomatic carotid stenosis (stroke/TIA 8.3% vs. 4.2%, P=0.040; mortality 4.1% vs. 0.7%, P=0.006). After adjusting for all confounding factors, female gender remained an important predicting factor for 30-day stroke/TIA in asymptomatic (OR=1.4, 95%CI 1.0-4.7, P=0.041) and symptomatic patients (OR=1.7, 95%CI 1.1-5.3, P=0.040), as well as for 30-day all-cause mortality in patients with asymptomatic (OR=1.5, 95%CI 1.1-4.1, P=0.030) and symptomatic carotid artery disease (OR=1.2, 95%CI 1.0-5.2, P=0.048).

CONCLUSIONS

Female gender is important predicting factor for stroke/TIA and all-cause mortality, both perioperative and during the first 30 days after carotid surgery.

A single-center retrospective study with 1-year follow-up after CEA in patients with severe carotid stenosis with contralateral carotid artery occlusion

Objective

To analyze the risk factors associated with adverse events after carotid endarterectomy (CEA) in patients with unilateral severe carotid stenosis and contralateral occlusion.

Methods

Patients were recruited for CEA between August 2014 and February 2020. CEA was performed under general anesthesia. The carotid clamp time (CCT; long CCT: >20 min) is defined as the period between clamp-on and clamp-off for the stenotic carotid artery. The perioperative factors and postoperative adverse events were recorded. All patients were followed up for 1 year after CEA.

Results

Sixty subjects (65.8 ± 7.2 years; 54 males) were included. Patients with adverse events had significantly longer CCT than those without adverse events (60% vs. 40%, P = 0.013). Univariate logistic regression analysis showed that a history of diabetes was significantly associated with adverse events (OR, 0.190; 95% CI, 0.045–0.814; P = 0.025); long CCT was significantly associated with adverse events (OR, 8.500; 95% CI, 1.617–44.682; P = 0.011). After adjusting for confounding factors, including age, sex, BMI, diabetes, PSV, long CCT, non–use of shunt, and history of stroke or TIA, the associations between diabetes and adverse events (OR, 0.113; 95% CI, 0.013–0.959; P = 0.046) were statistically significant; the associations between long CCT and adverse events (OR, 1.301; 95% CI, 1.049–1.613; P = 0.017) were statistically significant.

Conclusions

A longer carotid clamp time (>20 min) and a history of diabetes may increase the risk of adverse events in patients with unilateral severe carotid stenosis and contralateral occlusion after CEA. With good preoperative evaluation and intraoperative monitoring, the use of shunts may not be needed intraoperatively in patients with unilateral severe carotid stenosis and contralateral occlusion.

Identification of individuals at risk for postoperative cognitive dysfunction (POCD)

Postoperative cognitive dysfunction (POCD) is common, occurring in around 10-54% of individuals within first few weeks after surgery. Although the majority of POCD is less commonly persistent later than 3 months following surgery, the condition increases length of stay (LOS), mortality and long-term cognitive decline, raising the need for a broad screening to identify individuals at risk for POCD during the perioperative period. In this narrative review, we summarize preoperative, intraoperative and postoperative risk factors for POCD reported in last 5 years and discuss neuropsychological tools and potential biomarkers and time points for assessment that might be suitable for clinical use. We aim to provide crucial information for developing a strategy of routine screening for POCD, which may assist with better identification of at-risk individuals for early interventions. Very importantly, the utilization of a standardized strategy may also allow higher consistency and comparability across different studies.

The Diagnostic Accuracy of Intra-Operative Near Infrared Spectroscopy in Carotid Artery Endarterectomy Under Regional Anaesthesia: Systematic Review and Meta-Analysis

OBJECTIVE

Intra-operative near infrared spectroscopy (NIRS) is a non-invasive tool used to monitor regional cerebral oxygen saturation during carotid endarterectomy (CEA), for which accuracy remains unclear. Therefore, this systematic review and meta-analysis aimed to determine the diagnostic accuracy of NIRS in patients undergoing CEA under regional anaesthesia (RA).

DATA SOURCES

MEDLINE, Scopus, and Web of Science were searched for studies that compared NIRS with the "awake test" in patients undergoing CEA under RA.

REVIEW METHODS

Bivariable random effects meta-analysis was performed to determine the diagnostic accuracy of NIRS to detect cerebral ischaemia. Meta-regression was performed to explore causes of heterogeneity. Meta-analysis of proportions was also performed to determine the accuracy of NIRS in predicting 30 day stroke. Study quality was evaluated using the QUADAS-2 criteria.

RESULTS

Eleven primary studies were included, assessing 1 237 participants. The meta-analysis obtained a partial area under the summary receiver operating characteristic curve for diagnosing brain ischaemia of 0.646, with a summary sensitivity of 72.0% (95% confidence interval [CI] 58.1 - 82.7; I² = 48.6%) and a specificity of 84.1% (95% CI 78.5-88.4; I² = 48.6%). In meta-regression analysis, the frequency of hypertension (p = .011) and patients with symptomatic carotid stenosis (p = .031) were significant effect modifiers. Higher frequency of arterial hypertension (z score = -2.15; p = .032) and diabetes (z score = -2.12; p = .034) were associated with lower summary sensitivity, while a higher frequency of symptomatic carotid stenosis (z score = 2.11; p = .035) was associated with higher summary sensitivity. Point estimate sensitivity and specificity for predicting 30 day stroke occurrence were 41% (95% CI 19.5 - 66.6; I² = 0%) and 81.4% (95% CI 74.4 - 86.9, I² = 65.6%), respectively.

CONCLUSION

The results of this study suggest that NIRS as a cerebral monitoring technique does not have sufficiently high sensitivity or specificity to be used alone in the neurological monitoring of patients undergoing CEA under RA.

Cerebral Perfusion and Brain Oxygen Saturation Monitoring with: Jugular Venous Oxygen Saturation, Cerebral Oximetry, and Transcranial Doppler Ultrasonography

Accumulating evidence indicates that cerebral desaturation in the perioperative period occurs more frequently than recognized. Combining monitoring modalities that reflect different aspects of cerebral perfusion status, such as near-infrared spectroscopy, jugular bulb saturation, and transcranial Doppler ultrasonography, may provide an extended window for prevention, early detection, and prompt intervention in ongoing hypoxic/ischemic neuronal injury and, thereby, improve neurologic outcome. Such an approach would minimize the impact of limitations of each monitoring modality, while individual components complement each other, enhancing the accuracy of acquired information. Current literature has failed to demonstrate any clear-cut clinical benefit of these modalities on outcome prognosis.

Neuromonitoring during general anesthesia in non-neurologic surgery

Cerebral complications are common in perioperative settings even in non-neurosurgical procedures. These include postoperative cognitive dysfunction or delirium as well as cerebrovascular accidents. During surgery, it is essential to ensure an adequate degree of sedation and analgesia, and at the same time, to provide hemodynamic and respiratory stability in order to minimize neurological complications. In this context, the role of neuromonitoring in the operating room is gaining interest, even in the non-neurolosurgical population. The use of multimodal neuromonitoring can potentially reduce the occurrence of adverse effects during and after surgery, and optimize the administration of anesthetic drugs. In addition to the traditional focus on monitoring hemodynamic and respiratory systems during general anesthesia, the ability to constantly monitor the activity and maintenance of brain homeostasis, creating evidence-based protocols, should also become part of the standard of care: in this challenge, neuromonitoring comes to our aid. In this review, we aim to describe the role of the main types of noninvasive neuromonitoring such as those based on electroencephalography (EEG) waves (EEG, Entropy module, Bispectral Index, Narcotrend Monitor), near-infrared spectroscopy (NIRS) based on noninvasive measurement of cerebral regional oxygenation, and Transcranial Doppler used in the perioperative settings in non-neurosurgical intervention. We also describe the advantages, disadvantage, and limitation of each monitoring technique.

Safe carotid endarterectomy: "one fits all strategy"

INTRODUCTION

Carotid artery stenosis of 50% or more in the extracranial internal carotid artery is responsible for 10-15% of all strokes. Interventional treatment options include carotid endarterectomy and carotid artery stenting, where endarterectomy is proven to be superior.

AIM

In this study, we report the carotid endarterectomy results of patients we operated on using the strategy we termed the "one fits all strategy".

MATERIAL AND METHODS

Seventy-six patients undergoing carotid endarterectomy between July 2016 and April 2020 were retrospectively studied. Conventional endarterectomy under general anesthesia with primary closure of the arteriotomy was performed in all patients. We used a near infrared spectroscopy oximeter to measure regional cerebral oxygenation continuously throughout the surgery.

RESULTS

The mean age of the patients was 70.96 8.15 years. There were 52 male and 24 female patients. The mean follow-up time was 20.6 ±13.6 months. Coronary artery disease was detected in 52 (73.6%) patients. Coronary artery bypass operation was indicated in 19 patients in whom a staged approach was performed in 13 and a reverse staged approach in 1. There were two perioperative strokes one of which recovered fully spontaneously and the other partially with physiotherapy. Eight cases were revised due to hematoma formation.

CONCLUSIONS

Carotid endarterectomy continues to prove its safety in carotid artery stenosis patients. Continuous cerebral oxygenation monitoring is indispensable for carotid surgery. Despite discrepancies in surgical techniques, we believe that "one fits all strategy: general anesthesia, conventional endarterectomy without patch plasty, never shunter and always NIRS monitorization" may be used safely in patients undergoing carotid endarterectomy.

Efficacy of near-infrared spectroscopy cerebral oximetry on detection of critical cerebral perfusion during carotid endarterectomy under regional anesthesia

Summary: 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.