Total Intravenous Versus Volatile Induction and Maintenance of Anesthesia in Elective Carotid Endarterectomy: Effects on Cerebral Oxygenation and Cognitive Functions

Effects of anesthesia on cerebral oxygen saturation and prevention of brain injury during carotid endarterectomy

BACKGROUND

This study aimed to investigate the effects of general intravenous anesthesia and combined inhalation anesthesia on regional saturation of oxygen (rSO2) and cerebral hemodynamics during carotid endarterectomy (CEA). Optimizing intraoperative brain protection strategies has become a key focus in CEA research.

METHODS

Fifty-four patients (43 males, 11 females, aged 44-80) undergoing unilateral CEA were randomly assigned to Group IVA (intravenous anesthesia) or Group CIA (combined inhalation anesthesia), with 27 patients each. Group IVA was maintained with propofol and remifentanil, while Group CIA used sevoflurane, propofol, and remifentanil, with sevoflurane stopped after carotid exposure. Hemodynamics were controlled at various stages: ±10% before clamping, + 20% during clamping (metaraminol), and 0 to -10% after exposure. HR, MAP, and rSO₂ were recorded at T0 (pre-induction), T1 (pre-clamping), T2 (post-clamping), T3 (5 min post-clamping), T4 (10 min post-clamping), T5 (15 min post-clamping), and T6 (15 min post-reperfusion). Blood samples were taken at T1, T6, and T7 (24 h post-surgery) for blood gas and S100-β analysis.

RESULTS

No significant differences in rSO₂ were observed at T0 and T6 (P > 0.05). However, Group CIA had significantly higher rScO₂ at T1, T2, T3, T4, and T5 (P < 0.05). From T2 to T5, rSO₂ increased in both groups (P < 0.05). MAP and HR showed no significant differences (P > 0.05). ΔrSO₂ increased more in Group CIA (P < 0.05). At T6, S100-β protein was higher in Group IVA (P = 0.016), and pH differed significantly at T1 (P = 0.009). No other significant differences were observed.

CONCLUSION

Both intravenous and combined inhalation anesthesia may reduce rSO₂ decline during temporary clamping in CEA. Combined inhalation anesthesia showed a trend toward higher rSO₂ levels, potentially leading to better outcomes, but further studies are needed to confirm these findings.

RETROSPECTIVELY REGISTERED CLINICAL TRIAL NUMBER

ISRCTN17014575; Registration Date: 2024/6/10.

Emerging Insights into Postoperative Neurocognitive Disorders: The Role of Signaling Across the Gut-Brain Axis

The pathophysiological regulatory mechanisms in postoperative neurocognitive disorders (PNCDs) are intricately complex. Currently, the pathogenesis of PNCDs has not been fully elucidated. The mechanism involved may include a variety of factors, such as neuroinflammation, oxidative stress, and neuroendocrine dysregulation. Research into the gut microbiota-induced regulations on brain functions is increasingly becoming a focal point of exploration. Emerging evidence has shown that intestinal bacteria may play an essential role in maintaining the homeostasis of various physiological systems and regulating disease occurrence. Recent studies have confirmed the association of the gut-brain axis with central nervous system diseases. However, the regulatory effects of this axis in the pathogenesis of PNCDs remain unclear. Therefore, this paper intends to review the bidirectional signaling and mechanism of the gut-brain axis in PNCDs, summarize the latest research progress, and discuss the possible mechanism of intestinal bacteria affecting nervous system diseases. This review is aimed at providing a scientific reference for predicting the clinical risk of PNCD patients and identifying early diagnostic markers and prevention targets.

Propofol-Based Anesthesia Maintenance and/or Volatile Anesthetics during Intracranial Aneurysm Repair: A Comparative Analysis of Neurological Outcomes

BACKGROUND

Volatile and intravenous anesthetics have substantial effects on physiological functions, notably influencing neurological function and susceptibility to injury. Despite the importance of the anesthetic approach, data on its relative risks or benefits during surgical clipping or endovascular treatments for unruptured intracranial aneurysms (UIAs) remains scant. We investigated whether using volatile anesthetics alone or in combination with propofol infusion yields superior neurological outcomes following UIA obliteration.

METHODS

We retrospectively reviewed 1001 patients who underwent open or endovascular treatment for UIA, of whom 596 had short- and long-term neurological outcome data (modified Rankin Scale) recorded. Multivariable ordinal regression analysis was performed to examine the association between the anesthetic approach and outcomes.

RESULTS

Of 1001 patients, 765 received volatile anesthetics alone, while 236 received propofol infusion and volatile anesthetics (combined anesthetic group). Short-term neurological outcome data were available for 619 patients and long-term data for 596. No significant correlation was found between the anesthetic approach and neurologic outcomes, irrespective of the type of procedure (open craniotomy or endovascular treatment). The combined anesthetic group had a higher rate of ICU admission (p < 0.001) and longer ICU and hospital length of stay (LOS, p < 0.001). Similarly, a subgroup analysis revealed longer ICU and hospital LOS (p < 0.0001 and p < 0.001, respectively) in patients who underwent endovascular UIA obliteration under a combined anesthetic approach (n = 678).

CONCLUSIONS

The addition of propofol to volatile anesthetics during UIA obliteration does not provide short- or long-term benefits to neurologic outcomes. Compared to volatile anesthetics alone, the combination of propofol and volatile anesthetics may be associated with an increased rate of ICU admission, as well as longer ICU and hospital LOS.

Neuroprotection Is in the Air-Inhaled Gases on Their Way to the Neurons

Cerebral injury is a leading cause of long-term disability and mortality. Common causes include major cardiovascular events, such as cardiac arrest, ischemic stroke, and subarachnoid hemorrhage, traumatic brain injury, and neurodegenerative as well as neuroinflammatory disorders. Despite improvements in pharmacological and interventional treatment options, due to the brain's limited regeneration potential, survival is often associated with the impairment of crucial functions that lead to occupational inability and enormous economic burden. For decades, researchers have therefore been investigating adjuvant therapeutic options to alleviate neuronal cell death. Although promising in preclinical studies, a huge variety of drugs thought to provide neuroprotective effects failed in clinical trials. However, utilizing medical gases, noble gases, and gaseous molecules as supportive treatment options may offer new perspectives for patients suffering neuronal damage. This review provides an overview of current research, potentials and mechanisms of these substances as a promising therapeutic alternative for the treatment of cerebral injury.

A comparison of the NeurOs® and the INVOS 5100C® cerebral oximeter during variations of the partial pressure of carbon dioxide and fractional inspiratory concentration of oxygen

This prospective method comparison study compared cerebral oxygen saturation (ScO₂) measurement performance of the new cerebral oximeter (NeurOs®, Mespere LifeSciences, Ontario, Canada) in comparison to the established INVOS 5100C® (Medtronic, Boulder, USA) cerebral oximeter. We performed measurements during different levels of carbon dioxide pressure (PaCO₂) during hyper- and hypoventilation and different levels of arterial oxygen saturation (SaO₂) induced by variation of the inspiratory fraction of oxygen (FiO₂). 59 anesthetized cardiac and vascular surgical patients were studied during hemodynamically stable conditions. Two versions of the NeurOs® oximeter were used in 39 and 20 patients, respectively: an older version with one bi-hemispherical sensor attached to the midline of the forehead and a newer version with two sensors that were attached to the left and right forehead. Alternating measurements of ScO₂ with the INVOS® oximeter (bifrontal sensors) and the NeurOs® oximeter were performed during baseline conditions and after PaCO₂ had been randomly in- and decreased by changes in ventilation (constant FiO₂) and SaO₂ had been randomly modified by variations in FiO₂ (constant PaCO₂). Employing the most recent NeurOs® version, measurements were additionally performed in a default and a high penetration mode. Bland-Altman analyses revealed comparable bias and limits of agreement for INVOS® and NeurOS® measurements during baseline conditions when using the bi-hemispherical sensor and the version with two sensors, respectively. Consequently, further analyses were performed on the pooled data of 59 patients. Bland-Altman analysis for repeated measurements revealed a bias of - 0.5%, a lower limit of agreement of - 16.3% (95% CI - 19.6 to - 13.7%) and an upper limit of agreement of 15.4% (95% CI 12.8 to 18.8%) during variations of PaCO₂. The respective analysis during changes in SaO₂ induced by variation of the FiO₂ revealed a bias of - 0.8%, a lower limit of agreement of - 16.3% (95% CI - 19.7 to - 13.6%) and an upper limit of agreement of 14.7% (95% CI 12.1 to 18.2%). Both analyses showed a proportional error. No significant differences in ScO₂ were observed during measurements with the bi-frontal sensors in the default as well as the high penetration mode. The ScO₂ measurement performance of the NeurOs® cerebral oximeter is not interchangeable with the INVOS® cerebral oximeter during variations of ventilation and oxygenation in elective cardiac or vascular surgical patients. The lack of reactivity to changes in ventilation (by variation of PaCO₂) and oxygen delivery (by variation of FiO₂) question the reliability of NeurOs® measurements to reflect changes in cerebral blood flow and cerebral oxygen balance. This holds true not only for different sensor positions at the forehead but also for different modes of penetration.

Association between post-operative delirium and use of volatile anesthetics in the elderly: A real-world big data approach

STUDY OBJECTIVE

Early post-operative delirium is a common perioperative complication in the post anesthesia care unit. To date it is unknown if a specific anesthetic regime can affect the incidence of delirium after surgery. Our objective was to examine the effect of volatile anesthetics on post-operative delirium.

DESIGN

Single Center Observational Study.

SETTING

Post Anesthesia Care Units at a German tertiary medical center.

PATIENTS

30,075 patients receiving general anesthesia for surgery.

MEASUREMENTS

Delirium was assessed with the Nursing Delirium Screening Scale at the end of the recovery period. Subgroup-specific effects of volatile anesthetics on post-operative delirium were estimated using generalized-linear-model trees with inverse probability of treatment weighting. We further assessed the age-specific effect of volatiles using logistic regression models.

MAIN RESULTS

Out of 30,075 records, 956 patients (3.2%) developed delirium in the post anesthesia care unit. On average, patients who developed delirium were older than patients without delirium. We found volatile anesthetics to increase the risk (Odds exp. (B) for delirium in the elderly 1.8-fold compared to total intravenous anesthesia. Odds increases with unplanned surgery 3.0-fold. In the very old (87 years or older), the increase in delirium is 6.2-fold. This result was confirmed with internal validation and in a logistic regression model.

CONCLUSIONS

Our exploratory study indicates that early postoperative delirium is associated with the use of volatile anesthetics especially in the sub-cohort of patients aged 75 years and above. Further studies should include both volatile and intravenous anesthetics to find the ideal anesthetic in elderly patients.

Comparison of the Effects of Propofol and Sevoflurane Anesthesia on Optic Nerve Sheath Diameter in Robot-Assisted Laparoscopic Gynecology Surgery: A Randomized Controlled Trial

Optic nerve sheath diameter (ONSD) is used as a surrogate parameter for intracranial pressure. This study was conducted to evaluate the effect of the anesthetics (sevoflurane and propofol) on ONSD in women undergoing robotic surgery. The 42 patients who were scheduled for robot-assisted gynecology surgery were randomly allocated to the sevoflurane group or the propofol group. ONSD was recorded at 10 min after the induction of anesthesia (T0); 5 min, 20 min, and 40 min after carbon dioxide pneumoperitoneum was induced and the patients were put in a steep Trendelenburg position (T1, T2, and T3, respectively); and at skin closure after desufflation of the pneumoperitoneum (T4). Patients were observed for postoperative nausea and vomiting (PONV) during the immediate postoperative period. The propofol group had significantly lower ONSD than the sevoflurane group at T3. Mean ONSD values continuously increased from T0 to T3 in both groups. Two patients in the sevoflurane group experienced PONV. This study suggests that propofol anesthesia caused a lower increase in ONSD than sevoflurane anesthesia.

Identification of the transcription factor, AFF4, as a new target of miR-203 in CNS

MiR-203 was identified as a hub of a potential regulatory miRNA network in central nervous system. Overexpressing of miR-203 in the frontal cortex of C57BL/6J wild type mouse induced neurodegeneration by increasing the apoptotic pathway and neuron death. AFF4, a transcription factor, was identified as a new bona fida protein target of miR-203 in CNS. The miRNA:mRNA interaction of miR-203 and AFF4 was verified using Dural-luciferase assay. Down-regulated expression of AFF4 was induced by overexpressing miR-203 both in vitro and in vivo. Open field test, Y maze and Morris water maze test were conducted for the behavioral assessment of the mice with stereotactic injection of lentiviral vector overexpressing miR-203 in the hippocampus. No anxiety-like behavior or impaired cognition was noticed in these mice. Consistent with the results of the behavioral assessment, the electron micrograph and Nissl staining revealed no significant change in the synaptic density and no neuron injuries in the hippocampus of mice overexpressing miR-203, respectively. Our results indicated that instead of promoting neurodegenerative phenotype, a more profound function should be ascribed to miR-203 in regulating neuron behavioral activities and cognition. Neuron-type specific functions of miR-203 are likely to be executed via its various downstream protein interactors.

Intravenous versus Volatile Anesthetic Effects on Postoperative Cognition in Elderly Patients Undergoing Laparoscopic Abdominal Surgery

BACKGROUND

Delayed neurocognitive recovery after surgery is associated with poor outcome. Most surgeries require general anesthesia, of which sevoflurane and propofol are the most commonly used inhalational and intravenous anesthetics. The authors tested the primary hypothesis that patients with laparoscopic abdominal surgery under propofol-based anesthesia have a lower incidence of delayed neurocognitive recovery than patients under sevoflurane-based anesthesia. A second hypothesis is that there were blood biomarkers for predicting delayed neurocognitive recovery to occur.

METHODS

A randomized, double-blind, parallel, controlled study was performed at four hospitals in China. Elderly patients (60 yr and older) undergoing laparoscopic abdominal surgery that was likely longer than 2 h were randomized to a propofol- or sevoflurane-based regimen to maintain general anesthesia. A minimum of 221 patients was planned for each group to detect a one-third decrease in delayed neurocognitive recovery incidence in propofol group compared with sevoflurane group. The primary outcome was delayed neurocognitive recovery incidence 5 to 7 days after surgery.

RESULTS

A total of 544 patients were enrolled, with 272 patients in each group. Of these patients, 226 in the propofol group and 221 in the sevoflurane group completed the needed neuropsychological tests for diagnosing delayed neurocognitive recovery, and 46 (20.8%) in the sevoflurane group and 38 (16.8%) in the propofol group met the criteria for delayed neurocognitive recovery (odds ratio, 0.77; 95% CI, 0.48 to 1.24; P = 0.279). A high blood interleukin-6 concentration at 1 h after skin incision was associated with an increased likelihood of delayed neurocognitive recovery (odds ratio, 1.04; 95% CI, 1.01 to 1.07; P = 0.007). Adverse event incidences were similar in both groups.

CONCLUSIONS

Anesthetic choice between propofol and sevoflurane did not appear to affect the incidence of delayed neurocognitive recovery 5 to 7 days after laparoscopic abdominal surgery. A high blood interleukin-6 concentration after surgical incision may be an independent risk factor for delayed neurocognitive recovery.

EDITOR’S PERSPECTIVE

Effects of Volatile Anesthetics on Postoperative Ischemic Stroke Incidence

Background

Preclinical studies suggest that volatile anesthetics decrease infarct volume and improve the outcome of ischemic stroke. This study aims to determine their effect during noncardiac surgery on postoperative ischemic stroke incidence.

Methods and Results

This was a retrospective cohort study of surgical patients undergoing general anesthesia at 2 tertiary care centers in Boston, MA, between October 2005 and September 2017. Exclusion criteria comprised brain death, age <18 years, cardiac surgery, and missing covariate data. The exposure was defined as median age‐adjusted minimum alveolar concentration of all intraoperative measurements of desflurane, sevoflurane, and isoflurane. The primary outcome was postoperative ischemic stroke within 30 days. Among 314 932 patients, 1957 (0.6%) experienced the primary outcome. Higher doses of volatile anesthetics had a protective effect on postoperative ischemic stroke incidence (adjusted odds ratio per 1 minimum alveolar concentration increase 0.49, 95% CI, 0.40–0.59, P<0.001). In Cox proportional hazards regression, the effect was observed for 17 postoperative days (postoperative day 1: hazard ratio (HR), 0.56; 95% CI, 0.48–0.65; versus day 17: HR, 0.85; 95% CI, 0.74–0.99). Volatile anesthetics were also associated with lower stroke severity: Every 1‐unit increase in minimum alveolar concentration was associated with a 0.006‐unit decrease in the National Institutes of Health Stroke Scale (95% CI, −0.01 to −0.002, P=0.002). The effects were robust throughout various sensitivity analyses including adjustment for anesthesia providers as random effect.

Conclusions

Among patients undergoing noncardiac surgery, volatile anesthetics showed a dose‐dependent protective effect on the incidence and severity of early postoperative ischemic stroke.

The sensitivity and specificity of statistical rules for diagnosing delayed neurocognitive recovery with Montreal cognitive assessment in elderly surgical patients: A cohort study

Delayed neurocognitive recovery (DNR) is common in elderly patients after major noncardiac surgery. This study was designed to investigate the best statistical rule in diagnosing DNR with the Montreal cognitive assessment (MoCA) in elderly surgical patients.This was a cohort study. One hundred seventy-five elderly (60 years or over) patients who were scheduled to undergo major noncardiac surgery were enrolled. A battery of neuropsychological tests and the MoCA were employed to test cognitive function at the day before and on fifth day after surgery. Fifty-three age- and education-matched nonsurgical control subjects completed cognitive assessment with the same instruments at the same time interval. The definition of the international study of postoperative cognitive dysfunction (ISPOCD 1) was adopted as the standard reference for diagnosing DNR. With the MoCA, the following rules were used to diagnose DNR: the cut-off point of ≤26; the 1 standard deviation decline from baseline; the 2 scores decline from baseline; and the Z score of ≥1.96. The sensitivity and specificity as well as the area under receiver operating characteristic curve for the above rules in diagnosis of DNR were calculated.The incidence of DNR was 13.1% (23/175) according to the ISPOCD1 definition. When compared with the standard reference, the 2 scores rule showed the best combination of sensitivity (82.6%, 95% confidence interval [CI] 67.1%-98.1%) and specificity (82.2%, 95% CI 76.2%-88.3%); it also had the largest area under receiver operating characteristic curve (0.824, 95% CI 0.728-0.921, P < .001). The cut-off point rule showed high sensitivity (95.7%) and low specificity (37.5%), whereas the 1 standard deviation and the Z score rules showed low sensitivity (47.8% and 21.7%, respectively) and high specificity (93.4% and 97.3%, respectively).Compared with the ISPOCD1 definition, the 2 scores rule with MoCA had the best combination of sensitivity and specificity to diagnose DNR.

Outcomes of Carotid Endarterectomy according to the Anesthetic Method: General versus Regional Anesthesia

Background

The surgical strategies for carotid endarterectomy (CEA) vary in terms of the anesthesia method, neurological monitoring, shunt usage, and closure technique, and no gold-standard procedure has been established yet. We aimed to analyze the feasibility and benefits of CEA under regional anesthesia (RA) and CEA under general anesthesia (GA).

Methods

Between June 2012 and December 2017, 65 patients who had undergone CEA were enrolled, and their medical records were prospectively collected and retrospectively reviewed. A total of 35 patients underwent CEA under RA with cervical plexus block, whereas 30 patients underwent CEA under GA. In the RA group, a carotid shunt was selectively used for patients who exhibited negative results on the awake test. In contrast, such a shunt was used for all patients in the GA group.

Results

There were no cases of postoperative stroke, cardiovascular events, or mortality. Nerve injuries were noted in 4 patients (3 in the RA group and 1 in the GA group), but they fully recovered prior to discharge. Operative time and clamp time were shorter in the RA group than in the GA group (119.29±27.71 min vs. 161.43±20.79 min, p<0.001; 30.57±6.80 min vs. 51.77±13.38 min, p<0.001, respectively). The hospital stay was shorter in the RA group than in the GA group (14.6±5.05 days vs. 18.97±8.92 days, p=0.022). None of the patients experienced a stroke or restenosis during the 27.23±20.3-month follow-up period.

Conclusion

RA with a reliable awake test reduces shunt use and decreases the clamp and operative times of CEA, eventually resulting in a reduced length of hospital stay.

Comparison of the Effects of Desflurane and Sevoflurane on Cerebral Oxygen Saturation in Patients Undergoing Thyroidectomy: A Randomised Controlled Clinical Study

Objective

The commonly performed sitting position with head extended during thyroidectomy has been shown to cause adverse effects on cerebral regional oxygen saturation (CrSO2). Therefore, the present study aimed to investigate the effects of two well-known anaesthetic agents, desflurane and sevoflurane, on CrSO2 in patients undergoing thyroidectomy in the semi-sitting position by near-infra-red spectroscopy monitoring.

Methods

The study included 60 patients aged 18-65 years, with an American Society of Anesthesiologists (ASA) physical status classification score I-III, who underwent elective thyroidectomy in the semi-sitting position. The patients were randomly divided into two groups, depending on the anaesthetic agent administered: (1) sevoflurane group (Group S; n=30) and (2) desflurane group (Group D; n=30). After intubation, the patients were placed in a 45-degree semi-sitting position. Vital signs and the CrSO2 levels in both hemispheres were recorded both pre-induction and at the induction minute 1, post-intubation, post-positioning, every 5 minutes intraoperatively and in the case of sudden changes.

Results

No significant difference was found between the groups in terms of age, height, body weight, the ASA score, operative time and left- and right-hemisphere CrSO2 (p>0.05). Moreover, the two groups were statistically similar to each other with regard to peripheral capillary oxygen saturation, heart rate, systolic and diastolic blood pressure, mean artery pressure and end-tidal CO₂ (ETCO₂) levels.

Conclusion

Desflurane and sevoflurane had similar effects in the preservation of CrSO2 in patients undergoing thyroidectomy in the semi-sitting position.

Purine nucleoside use as surrogate markers of cerebral ischaemia during local and general anaesthetic carotid endarterectomy

Objectives:

In periods of cerebral ischaemia, adenosine triphosphate is metabolised, leading to accumulation of adenosine inosine and hypoxanthine. These can be measured in real time using peripheral blood samples intraoperatively. The primary aim of this study was to describe changes in purine concentrations in a cohort of patients undergoing carotid endarterectomy under general anaesthetic, and to evaluate correlation between changes in values with major perioperative steps. The secondary aim was to compare changes in concentrations with a previous cohort of patients who had undergone carotid endarterectomy under local anaesthetic.

Methods:

This was a prospective observational study. Purine concentrations were determined from arterial line samples and measured via an amperometric biosensor at specific time points during carotid endarterectomy. Mean arterial pressure was manipulated to maintain steady cerebral perfusion pressure throughout the procedure. These results were analysed against data from a cohort of patients who underwent carotid endarterectomy under local anaesthetic in previously published work.

Results:

Valid results were obtained for 37 patients. Purine concentrations at baseline were 3.02 ± 1.11 µM and 3.16 ± 1.85 µM for the unshunted and shunted cohorts, respectively. There was no significant change after 30 min of carotid clamping at 2.07 ± 0.89 and 2.4 ± 3.09 µM, respectively (both p > 0.05). Peak purine during the clamp phase in the loco-regional anaesthetic cohort was 6.70 ± 3.4 µM, which was significantly raised compared to both general anaesthetic cohorts (p = 0.004). There were no perioperative neurological events in either cohort.

Conclusion:

This small study does not demonstrate conclusive evidence that purine nucleosides can be used as a marker of cerebral ischaemia; the comparisons to the loco-regional anaesthetic data offer information about differences in the cerebral adenosine triphosphate metabolism between general anaesthetic and loco-regional anaesthetic. We hypothesise that the lack of a rise in purine nucleosides under general anaesthetic may be caused by a decrease in the cerebral metabolic rate and loss of metabolic rate-blood flow coupling caused by general anaesthetic agents.