Effect of Vitamin C Infusion on Cerebral Oximetry During General Anesthesia for Carotid Endarterectomy in Diabetic Patients

Background

There is conflicting information about the effect of vitamin C on brain oxygenation during anesthesia.

Objectives

The current study was designed and performed to assess the effect of vitamin C infusion and brain oxygenation with cerebral oximetry on improving brain perfusion during general anesthesia in vascular surgery of diabetic patients.

Methods

This randomized clinical trial was performed on patients candidates for endarterectomy under general anesthesia and referred to Taleghani Hospital in Tehran, Iran, during 2019 - 2020. Considering inclusion criteria, the patients were divided into placebo and intervention groups. The patients in the placebo group received 500 mL of isotonic saline. In the intervention group, the patients received 1 g of vitamin C diluted in 500 mL of isotonic saline by infusion half an hour before anesthesia induction. Patients' oxygen levels were continuously measured by a cerebral oximetry sensor. The patients were put in a supine position for 10 minutes before and after anesthesia. At the end of the surgery, the indicators considered in the study were evaluated.

Results

No considerable difference was observed between systolic and diastolic blood pressure, heart rate, mean arterial pressure, partial pressure of carbon dioxide, oxygen saturation, regional oxygen saturation, supercritical carbon dioxide, and end-tidal carbon dioxide in total and between the two groups in the three stages before and after anesthesia induction and at the end of surgery (P > 0.05). Additionally, there was no significant difference between blood sugar (BS) levels in the study groups (P > 0.05) but in BS levels at three stages before and after anesthesia induction and at the end of the surgery, with a significant difference (P < 0.05).

Conclusions

The amount of perfusion in the two groups and, therefore, in total at the three stages before and after anesthesia induction and at the end of surgery is not different.

Assessment of Determinants of Value in Carotid Endarterectomy

OBJECTIVE

Over 150,000 carotid endarterectomies (CEA) are performed annually worldwide, accounting for $900 million in the US alone. How cost/spending and quality are related is not well understood but remains an essential component in maximizing value. We sought to identify determinants of variability in hospital 90-day episode value for CEA.

METHODS

Medicare and private-payer admissions for CEA from January 2^nd, 2014 to August 28^th, 2020 were linked to retrospective clinical registry data for hospitals in Michigan performing vascular surgery. Hospital-specific risk-adjusted 30-day composite complications (defined as reoperation, new neurologic deficit, myocardial infarction, additional procedure including CEA or carotid artery stenting, readmission, or mortality) and 30-day risk-adjusted, price standardized total episode payments were used to categorize hospitals into low or high value by defining the intersection between complications and spending.

RESULTS

A total of 6595 patients across 39 hospitals were identified across both datasets. Patients at low-value hospitals had a higher rate of 30-day composite complications (17.9% vs 10.1%, p<0.001) driven by a significantly higher rate of reoperation (3.0% vs 1.4%, p=0.016), readmission (10.7% vs 6.2%, p=0.012), new neurologic deficit (4.6% vs 2.3%, p=0.017), and mortality (1.6% vs 0.6%, p<0.049). Mean total episode payments were $19,635 at low-value hospitals compared to $15,709 at high-value hospitals driven by index hospitalization ($10,800 vs $9587, p= 0.002), professional ($3421 vs $2827, p < 0.001), readmission ($3011 vs $1826, p < 0.001) and post-acute care payments ($2335 vs $1486, p < 0.001). Findings were similar when only including patients who did not suffer a complication.

CONCLUSIONS

There is tremendous variation in both quality and payments across hospitals included for CEA. Importantly, costs were higher at low-value hospitals independent of post-operative complication. There appears to be little to no relationship between total episode spending and surgical quality, suggesting that improvements in value may be possible by decreasing total episode cost without affecting surgical outcomes.

[The relationship of carotid artery disease with mental and neurocognitive disorders]

Carotid stenosis constitutes a common vascular disease that significantly affects cerebral blood flow and thus is associated with patients' cognitive functions. Carotid revascularization techniques [carotid endarterectomy (CEA) and carotid artery stenting (CAS)] may benefit cognition, though there are opposing findings, reporting an apparent decrement in cognitive function, no effect, or an apparent improvement after revascularization. A great number of studies are trying to evaluate the effect of carotid revascularization (CEA, CAS) on patients' cognitive functions, as well as on their psychological condition and quality of life through a baseline and follow-up neuropsychological examination. Recent reviews refer only to the narrow limits of cognitive deficits that may be attributed to carotid stenosis, rather than elucidating the outfit of all aspects of mental and cognitive correlations. Most of those findings depict controversy in current literature as far as the neuropsychological effects of carotid revascularization techniques are concerned, while clinical entities of "vascular dementia" and "vascular depression", as well as intercurrent vascular risk factors are also addressed. This might be taken into consideration, when determining the optimal therapeutic strategy for tackling carotid artery occlusive disease, while best practice clinical decisions should be still focused on stroke prevention and symptoms alleviation, until further research on the field of neuroangiology presents undisputable conclusions regarding the underlying effects of revascularization on mood and cognition. Τhe neurovascular interface, as far as mental and neurocognitive impact of carotid stenosis is concerned, also, comprises, the conceptual pathophysiological entity of "atheroinflammation", underscoring the association of vascular lesions with cognitive impairment, major depressive disorder and bipolar disorder. Chronic recurrent ischemia and chronic low perfusion are also addressed from neurocognitive aspect, regarding therapeutic strategies that might be preferred so as to reduce the burden of chronic cerebrovascular disease in both symptomatic and asymptomatic patients, given the fact that inflammatory processes of vascular complexion underlie both neuroinflammation and atherosclerosis, affecting cerebral perfusion as well as cortical blood flow.

Coexisting Coronary and Carotid Artery Disease: What We Did, What Happened

INTRODUCTION

There is no complete consensus on the three surgical methods and long-term consequences for coexisting coronary and carotid artery disease. We retrospectively evaluated the surgical results in this high-risk group in our clinic for a decade.

METHODS

Between 2005 and 2015, 196 patients were treated for combined carotid and coronary artery disease. A total of 50 patients were operated on with the staged method, 40 of which had carotid endarterectomy (CEA) priority, and 10 had coronary artery bypass grafting (CABG) priority. CABG and CEA were simultaneously performed in 82 patients; and in 64 asymptomatic patients with unilateral carotid artery lesions and stenosis over 70%, only CABG was done (64 patients). Results were evaluated by uni-/multivariate analyses for perioperative, early, and late postoperative data.

RESULTS

In the staged group, interval between the operations was 2.82±0.74 months. Perioperative and early postoperative (30 days) parameters did not differ between groups (P-value < 0.05). Postoperative follow-up time was averaged 94.9±38.3 months. Postoperative events were examined in three groups as (A) deaths (all cause), (B) cardiovascular events (non-fatal myocardial infarction, recurrent angina, congestive heart failure, palpitation), and (C) fatal neurological events (amaurosis fugax, transient ischemic attack, and stroke). When group C events were excluded, event-free actuarial survival rates were similar in all three methods (P=0.740). Actuarial survival rate was significantly different when all events were included (P=0.027). Neurological events increased markedly between months 34 and 66 (P=0.004).

CONCLUSION

Perioperative and early postoperative event-free survival rates were similar in all three methods. By the beginning of the 34th month, the only CABG group has been negatively separated due to neurological events. In the choice of methodology, "most threatened organ priority'' was considered as clinical parameter.

A systematic review of cognitive function after carotid endarterectomy in asymptomatic patients

OBJECTIVE

Asymptomatic carotid stenosis has been associated with a progressive decline in neurocognitive function. However, the effect of carotid endarterectomy on this process is poorly understood. We aimed to evaluate pre and post-operative cognitive function changes in asymptomatic patients after carotid endarterectomy METHODS: A systematic review of the existing reports in PubMed/MEDLINE, Embase, and Cochran databases was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analysis statement recommendations. All original retrospective or prospective studies (including cohort, cross-sectional, case-control, pilot studies, etc.) and clinical trials that compared pre and post-operative neurocognitive function in asymptomatic patients with carotid stenosis after CEA, which were published from January 2000 to April 2021 were identified and considered eligible for inclusion in the study.

RESULTS

Thirteen studies (502 CEAs) comparing cognitive function changes before and after CEA were identified. In seven studies with a total number of 272 patients, a mean age range of 67.3 ± 4.8 to 76.35 years old and after follow-up ranging between 1 and 12 months, overall cognitive function improved after CEA. However, in six studies with a total sample of 230, a mean age range of 68.6 ± 6.9 to 74.4±6.1 years, and follow-up ranged from 24 hours to 3 years, showed no change or decline in overall cognitive function after procedures.

CONCLUSIONS

The lack of standardization of specific cognitive tests and cognitive function assessment timing after CEA does not allow for definite conclusions to be made. However, improving the brain perfusion with combination of CEA and statin therapy may be a protective strategy against cognitive function decline.

Mast Cell Distribution in Human Carotid Atherosclerotic Plaque Differs Significantly by Histological Segment

OBJECTIVE

Mast cells (MCs) are important contributors to atherosclerotic plaque progression. For prospective studies on mast cell contributions to plaque instability, the distribution of intraplaque MCs needs to be elucidated. Plaque stability is generally histologically assessed by dividing the plaque specimen into segments to be scored on an ordinal scale. However, owing to competitive use, studies may have to deviate to adjacent segments, yet intersegment differences of plaque characteristics, especially MCs, are largely unknown. Therefore, the hypothesis that there is no segment to segment difference in MC distribution between atherosclerotic plaque segments was tested, and intersegment associations between MCs and other plaque characteristics was investigated.

METHODS

Twenty-six carotid atherosclerotic plaques from patients undergoing carotid endarterectomy included in the Athero-Express Biobank were analysed. The plaque was divided in 5 mm segments, differentiating between the culprit lesion (segment 0), adjacent segments (-1/+1) and more distant segments (-2/+2) for the presence of MCs. The associations between the intersegment distribution of MCs and smooth muscle cells, macrophage content, and microvessel density in the culprit lesion were studied.

RESULTS

A statistically significant difference in MCs/mm² between the different plaque segments (p < .001) was found, with a median of 2.79 (interquartile range [IQR] 1.63 - 7.10) for the culprit lesion, 1.34 (IQR 0.26 - 4.45) for the adjacent segment, and 0.62 (0.14 - 2.07) for the more distant segment. Post hoc analyses showed that intersegment differences were due to differences in MCs/mm² between the culprit and adjacent segment (p = .037) and between the culprit lesion and the more distant segment (p < .001). MCs/mm² in multiple different segments were positively correlated with microvessel density and macrophage content in the culprit lesion.

CONCLUSION

MC numbers reveal significant intersegment differences in human carotid plaques. Future histological studies on MCs should use a standardised segment for plaque characterisation as plaque segments cannot be used interchangeably for histological MC analyses.

Contralateral Stenosis and Echolucent Plaque Morphology are Associated with Elevated Stroke Risk in Patients Treated with Asymptomatic Carotid Artery Stenosis within a Controlled Clinical Trial (SPACE-2)

BACKGROUND

Asymptomatic carotid artery stenosis (ACS) has a low risk of stroke. To achieve an advantage over noninterventional best medical treatment (BMT), carotid endarterectomy (CEA) or carotid artery stenting (CAS) must be performed with the lowest possible risk of stroke. Therefore, an analysis of risk-elevating factors is essential. Grade of ipsilateral and contralateral stenosis as well as plaque morphology are known risk factors in ACS.

METHODS

The randomized, controlled, multicenter SPACE-2 trial had to be stopped prematurely after recruiting 513 patients. 203 patients were randomized to CEA, 197 to CAS, and 113 to BMT. Within one year, risk factors such as grade of stenosis and plaque morphology were analyzed.

RESULTS

Grade of contralateral stenosis (GCS) was higher in patients with any stroke (50%^ECST vs. 20%^ECST; p=0.012). Echolucent plaque morphology was associated with any stroke on the day of intervention (OR 5.23; p=0.041). In the periprocedural period, any stroke was correlated with GCS in the CEA group (70%^ECST vs. 20%^ECST; p=0.026) and with echolucent plaque morphology in the CAS group (6% vs. 1%; p=0.048). In multivariate analysis, occlusion of the contralateral carotid artery (CCO) was associated with risk of any stroke (OR 7.00; p=0.006), without heterogeneity between CEA and CAS.

CONCLUSION

In patients with asymptomatic carotid artery stenosis, GCS, CCO, as well as echolucent plaque morphology were associated with a higher risk of cerebrovascular events. The risk of stroke in the periprocedural period was increased by GCS in CEA and by echolucent plaque in CAS. Due to small sample size, results must be interpreted carefully.

The Effect of Hemodynamic Parameters on Cerebral Oxygenization During Carotid Endarterectomy

INTRODUCTION

Near-infrared spectroscopy (NIRS) is a non-invasive technique to detect cerebral ischemia by monitoring changes in regional cerebral oxygenation (rSO₂) in the frontal lobes. However, there are no studies showing the changes in NIRS values in response to hemodynamic variations during stages of carotid endarterectomy (CEA) procedure and clinical implications of these changes. The aim of this study was to determine if hemodynamic changes affect NIRS values during carotid endarterectomy and if our results may help to provide strategies for hemodynamic management in these patients.

METHODS

A total of 50 consecutive patients undergoing CEA were prospectively included in the study. NIRS was measured at first minute after clamping of carotid artery, and then systolic blood pressure was increased above 150 mmHg. NIRS values from both hemispheres were recorded simultaneously at certain time points and were analyzed to evaluate the changes at different stages of operation and to assess correlations with hemodynamic parameters.

RESULTS

NIRS values on the right and left sides were correlated with systolic (right P<0.001, R2:0.24; left P=0.02, R2:0.10) diastolic (right P<0.001, R2:0.36; left P=0.001, R2:0.18) and mean (right P<0.001, R2:0.33; left P=0.003, R2:0.17) blood pressures when the patient was under general anaesthesia. NIRS values were significantly lower than pre-incision values just after clamping of carotid artery in both hemispheres (P=0.005 for the right and P<0.001 for the left side).

CONCLUSION

NIRS values measured in our study show that there is a correlation between hemodynamic changes and cerebral oxygenation. This effect is especially pronounced while the patient is asleep and intubated, which implies the importance of close monitoring of patients with carotid disease during any surgery requiring general anaesthesia.

Preoperative Carotid Duplex Scanning in Patients Undergoing Coronary Artery Bypass Grafting

OBJECTIVE

The aim of this study was to determine the prevalence and risk factors of carotid artery stenosis (CAS) using carotid duplex ultrasound in patients undergoing coronary artery bypass grafting (CABG).

METHODS

This retrospective study was conducted between January 2017 and January 2018 and included 166 consecutive patients [130 males (78.31%), 36 females (21.69%); mean age: 64.25±9.78 years] who underwent elective and isolated CABG. Patients who had significant CAS (≥50% stenosis) were compared with patients who had non-significant CAS (<50% stenosis). Logistic regression analysis was applied across the selected parameters to identify risk factors for significant CAS.

RESULTS

Of all patients, 36 (21.68%) had CAS ≥50% and 8 (4.81%) had unilateral carotid stenosis ≥70%. Carotid endarterectomy/CABG was performed simultaneously in five (3.01%) patients. None of these patients had cardiac and neurological problems during the postoperative period. The overall incidence of cerebrovascular accident (CVA) after CABG was 1.20% (n=2). Age (P=0.011) and history of CVA (P=0.035) were significantly higher in the CAS ≥50 group than in the CAS <50 group. Significant CAS was identified as a risk factor for postoperative CVA (P=0.013).

CONCLUSION

Age and history of CVA were identified as risk factors for significant CAS. Furthermore, significant CAS was identified as a risk factor for postoperative CVA. For this reason, carotid screening is recommended for patients undergoing CABG even in the absence of associated risk factors.

Does Cognitive Dysfunction after Carotid Endarterectomy Vary by Statin Type or Dose?

Our previous work demonstrates that asymptomatic carotid endarterectomy (CEA) patients demonstrate less perioperative neurologic injury, defined as stroke and early cognitive dysfunction (eCD) observed within 24hr of CEA, when taking statins pre-operatively. This study examines whether the incidence of eCD observed 24hr after asymptomatic CEA varies as a function of statin type or dose. Patients with asymptomatic carotid stenosis scheduled for CEA consented to participate in an observational IRB-approved study (N=324). Patients were evaluated with an extensive battery of neuropsychometric tests pre-operatively and 24hr post-operatively. Of the 324 consented patients, 200 were taking statins. Patients taking pravastatin and fluvastatin exhibited no eCD, while patients taking lovastatin (17.7%) and rosuvastatin (16.7%) exhibited incidences of eCD similar to those not taking statins (20.2%). Patients taking simvastatin exhibited a significantly lower incidence of eCD than those taking atorvastatin (3.0% vs. 16.0%, P=0.005). Patients taking a maximal dose of any statin exhibited a significantly lower incidence of eCD than patients taking sub-maximal doses (2.7% vs. 15.9%, P=0.002). These observations suggest that the incidence of eCD may in fact vary as a function of statin type and that maximal doses may be the optimal dose for patients undergoing CEA. This variation may be due to the physico-chemical properties of statins such as lipophilicity, molecular size, and blood brain barrier penetrability. These findings should be used to inspire randomized prospective work to determine the safety, feasibility, and outcomes of optimizing statin use prior to CEA.