Prevention of Ischemic Neurologic Injury With Intraoperative Monitoring of Selected Cardiovascular and Cerebrovascular Procedures: Roles of Electroencephalography, Somatosensory Evoked Potentials, Transcranial Doppler, and Near-Infrared Spectroscopy

ASNM and ASN joint guidelines for transcranial Doppler ultrasonic monitoring: An update

Today, it seems prudent to reconsider how ultrasound technology can be used for providing intraoperative neurophysiologic monitoring that will result in better patient outcomes and decreased length and cost of hospitalization. An extensive and rapidly growing literature suggests that the essential hemodynamic information provided by transcranial Doppler (TCD) ultrasonography neuromonitoring (TCDNM) would provide effective monitoring modality for improving outcomes after different types of vascular, neurosurgical, orthopedic, cardiovascular, and cardiothoracic surgeries and some endovascular interventional or diagnostic procedures, like cardiac catheterization or cerebral angiography. Understanding, avoiding, and preventing peri- or postoperative complications, including neurological deficits following abovementioned surgeries, endovascular intervention, or diagnostic procedures, represents an area of great public and economic benefit for society, especially considering the aging population. The American Society of Neurophysiologic Monitoring and American Society of Neuroimaging Guidelines Committees formed a joint task force and developed updated guidelines to assist in the use of TCDNM in the surgical and intensive care settings. Specifically, these guidelines define (1) the objectives of TCD monitoring; (2) the responsibilities and behaviors of the neurosonographer during monitoring; (3) instrumentation and acquisition parameters; (4) safety considerations; (5) contemporary rationale for TCDNM; (6) TCDNM perspectives; and (7) major recommendations.

The Importance of Neuromonitoring in Non Brain Injured Patients

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2022. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2022. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from https://link.springer.com/bookseries/8901.

Predictive Factors of Perioperative Stroke-Related Mortality Following Vascular Surgery: A Retrospective Analysis

OBJECTIVE

Vascular surgical procedures have one of the highest risks of perioperative stroke and stroke-related mortality, yet the independent risk factors contributing to this increased mortality have not been described. Perioperative strokes are thought to result from a combination of embolism and hypoperfusion mechanisms. The purpose of this study is to describe the independent predictors of perioperative stroke-related mortality in the vascular surgical population using the Pennsylvania Health Care Cost Containment Council (PHC4) database which collects cause of death data.

METHODS

This retrospective, case-control study evaluated 4,128 patients aged 18-99 who underwent a vascular, non-carotid surgical procedure and subsequently suffered perioperative mortality. Common surgical comorbidities and risk factors for perioperative stroke, including carotid stenosis and atrial fibrillation, were evaluated in multivariate regression analysis.

RESULTS

Patients with carotid stenosis were 2.6 (aOR, 95% CI 1.4-4.5) times more likely to suffer perioperative mortality from stroke than from other causes. Additionally, in-hospital stroke, history of stroke, admission from a healthcare facility, and cancer were all positive predictive factors, whereas atrial fibrillation, emergency admission, hypertension, and diabetes were associated with decreased risk of perioperative stroke-related mortality.

CONCLUSIONS

Identification of vascular surgical population-specific predictors of stroke-related mortality can help to enhance preoperative risk-stratification tools and guide perioperative management of identified high-risk patients. Increased neurophysiologic monitoring in the perioperative period to prevent delays in diagnosis of perioperative stroke offers a strategy to reduce risk of perioperative stroke-related mortality in vascular surgical patients.

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.

Laser speckle contrast imaging of forehead cutaneous blood flow during carotid endarterectomy as a potential non-invasive method for surrogate monitoring of cerebral perfusion

Monitoring cerebral perfusion is important for goal-directed anesthesia. Taking advantage of the supply of the supraorbital region and Glabella from the internal carotid artery (ICA), we evaluated changes in cutaneous blood flow using laser speckle contrast imagining (LSCI) as a potential method for indirect real-time monitoring of cerebral perfusion. Nine patients (8 men, mean age 70 years) underwent eversion carotid endarterectomy under local anesthesia. Cutaneous blood flow of the forehead was monitored using LSCI. During clamping of the common carotid artery (CCA), ipsilateral supraorbital region and Glabellas cutaneous blood flow dropped from 334 ± 135 to 221 ± 109 AU (p = 0.023) (AU: arbitrary flux units) and from 384 ± 151 to 276 ± 107 AU (p = 0.023), respectively, whilst the contralateral supraorbital region cutaneous blood flow remained unchanged. The supraorbital cutaneous blood flow did not change significantly following reperfusion of the external carotid artery (ECA) (221 ± 109 to 281 ± 154 AU; p = 0.175) and ICA (281 ± 154 to 310 ± 184 AU; p = 01). A comparable trend for Glabella followed ECA (276 ± 107 to 342 ± 170 AU; p = 0.404) and ICA (342 ± 170 to 352 ± 191 AU; p = 01) reperfusion. In patients undergoing carotid endarterectomy under local anesthesia, LSCI of the supraorbital and Glabella regions reflected clamping of the CCA but did not distinguish reperfusion of the ICA from that of the ECA.

Evaluation of the brain hemodynamic response by means of near-infrared spectroscopy (NIRS) monitoring in patients with atherosclerotic carotid disease undergoing endarterectomy

Backgrounds

Near-infrared spectroscopy (NIRS) is non-invasive technique that detects hemodynamic alterations in tissues. It enables continuous monitoring of intracerebral vascular physiologic information. Due to its portable nature, NIRS may be used bedside or in the operating room.

Objectives

To evaluate use of NIRS for intraoperative monitoring of the brain hemodynamic response, during carotid endarterectomy.

Methods

10 patients with atherosclerotic carotid disease scheduled for endarterectomy were evaluated. After patients had been selected, they answered a questionnaire on epidemiological data and information about comorbidities and then carotid disease was confirmed with diagnostic methods. NRIS monitoring was used during the surgical procedure. The variables analyzed before, during and after carotid clamping were oxygen saturation (SatO₂), total hemoglobin (THb), reduced hemoglobin (RHb), and oxyhemoglobin (OHb). A p value of <0.05 was considered statistically significant.

Results

The results obtained from NIRS show that RHb and SatO₂ vary during the different stages of surgery. RHb levels are higher during clamping, when compared with the other two surgical stages. On the other hand, SatO₂ is lower during clamping.

Conclusions

During carotid endarterectomy, NIRS is a feasible, real-time, and non-invasive intracranial monitoring method that accurately and reliably measures the changes in intracerebral capillary hemodynamic conditions.

A rare case of life-threatening traumatic carotid artery dissection in a child

Penetrating injuries of the carotid and vertebral arteries are rare, but life-threatening conditions. There are still challenges in the first intervention management and patient treatment. Deciding which methods to apply in the first intervention, whether to perform imaging, and the preferred appropriate treatment for the patient (open surgery or endovascular intervention) plays a main role in the patient's survival without neurological deficit. The general management of trauma in penetrating neck injuries and the knowledge of special approaches to carotid artery injury are important for pediatric trauma centers. In this case report, we presented a case of penetrating carotid artery injury in a child who has recovered with no disability after a successful first intervention, surgical repair, and proper postoperative care.

Predictive value of transcranial evoked potentials during mechanical endovascular therapy for acute ischaemic stroke: a feasibility study

BACKGROUND AND PURPOSE

Mechanical endovascular therapy (MET) is a promising adjuvant or stand-alone therapy for acute ischaemic stroke caused by occlusion of a large vessel. Real-time monitoring of recanalisation success with regard to functional outcome is usually not possible because these procedures are mainly performed under general anaesthesia. We present a novel application for evoked potential monitoring for real-time evaluation of reperfusion success with respect to functional outcome during MET for acute ischaemic stroke.

METHODS

Prospective observational study from March 2012 to April 2013 of patients presenting with acute ischaemic stroke who were eligible for MET. Transcranial motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) were measured bilaterally during MET throughout the intervention. The electrophysiological data of the contralateral side served as control. Neurological outcome was assessed by the modified Rankin Scale and National Institutes of Health Stroke Scale at 0, 7 and 90 days following intervention.

RESULTS

20 patients were examined. MEPs and SSEPs were technically successful in 19 (95%) and 9 (45%) cases, respectively. Successful reperfusion was achieved in 16 cases. Functional recovery was observed in 14 patients. MEPs and SSEPs recovery status was a better predictor of functional recovery than successful reperfusion with a positive predictive value of 92%, 83% and 75% for MEPs, SSEPs and reperfusion, respectively.

CONCLUSIONS

MEPs and SSEPs are safe and feasible methods of real-time monitoring of reperfusion success with respect to functional outcome during MET for acute ischaemic stroke.

Controversies in the anesthetic management of intraoperative rupture of intracranial aneurysm

Despite great advancements in the management of aneurysmal subarachnoid hemorrhage (SAH), outcomes following SAH rupture have remained relatively unchanged. In addition, little data exists to guide the anesthetic management of intraoperative aneurysm rupture (IAR), though intraoperative management may have a significant effect on overall neurological outcomes. This review highlights the various controversies related to different anesthetic management related to aneurysm rupture. The first controversy relates to management of preexisting factors that affect risk of IAR. The second controversy relates to diagnostic techniques, particularly neurophysiological monitoring. The third controversy pertains to hemodynamic goals. The neuroprotective effects of various factors, including hypothermia, various anesthetic/pharmacologic agents, and burst suppression, remain poorly understood and have yet to be further elucidated. Different management strategies for IAR during aneurysmal clipping versus coiling also need further attention.

Neurophysiologic monitoring in neurosurgery

This article focuses on the application of neurophysiologic monitoring in uniquely neurosurgical procedures. Neurophysiologic monitoring provides functional testing and mapping to identify neural structures. Once identified, the functionality of the central and peripheral nervous system areas at risk for neurosurgical injury can be monitored. It discusses the use of motor-evoked potentials, sensory evoked potentials, electromyography and electroencephalography to assess neurologic change.

[Intraoperative electrophysiological monitoring with evoked potentials]

During the last 30 years intraoperative electrophysiological monitoring (IOEM) has gained increasing importance in monitoring the function of neuronal structures and the intraoperative detection of impending new neurological deficits. The use of IOEM could reduce the incidence of postoperative neurological deficits after various surgical procedures. Motor evoked potentials (MEP) seem to be superior to other methods for many indications regarding monitoring of the central nervous system. During the application of IOEM general anesthesia should be provided by total intravenous anesthesia with propofol with an emphasis on a continuous high opioid dosage. When intraoperative MEP or electromyography guidance is planned, muscle relaxation must be either completely omitted or maintained in a titrated dose range in a steady state. The IOEM can be performed by surgeons, neurologists and neurophysiologists or increasingly more by anesthesiologists. However, to guarantee a safe application and interpretation, sufficient knowledge of the effects of the surgical procedure and pharmacological and physiological influences on the neurophysiological findings are indispensable.

Cerebrovascular reacivity assessment in patients with carotid artery disease: a combined TCD and NIRS study

BACKGROUND AND PURPOSE

Transcranial Doppler (TCD) and near-infrared spectroscopy (NIRS) are two noninvasive diagnostic tools that have been shown to evaluate cerebral vasomotor reactivity by measuring changes in mean cerebral blood flow velocities (MCBFV) of proximal intracranial arteries and absolute brain-tissue oxygen-saturation (TOS) in microcirculation, respectively, during hemodynamic challenge. We evaluated the potential correlation between TCD and NIRS measurements of vasomotor reactivity (VMR) in patients with carotid artery disease (CARAD).

METHODS

Consecutive patients (n = 24) with CARAD underwent simultaneously TCD and NIRS examinations during voluntary breath-holding (BH). MCBFV and TOS values were recorded at baseline (BAS) and at the end of BH, while BH duration (DBH) was documented. VMR was quantified by means of TCD-BHI (Breath-holding Index: [MCBFV(BH) - MCBFV(BAS)]× 100/MCBFV(BAS)/DBH) and NIRS-BHI ([TOS(BH) - TOS(BAS)]× 100/ TOS(BAS)/DBH).

RESULTS

TCD-BHI correlated positively with NIRS-BHI in the affected side (r = .538, P = .007). A stronger correlation between TCD-BHI and NIRS-BHI was documented in the nonaffected side (r = .768, P< .001). After adjusting for demographic characteristics, stroke risk factors and symptomatic status NIRS-BHI was linearly and independently associated with TCD-BHI both in the affected (β:+ .813, P = .001) and unaffected (β:+ .823, P < .001) side.

CONCLUSIONS

Circulatory assessment of VMR in proximal cerebral vessels by TCD correlates positively to functional measurements of VMR in microcirculation by NIRS in CARAD patients.

Intracardiac shunting and stroke in children: a systematic review

In adults, patent foramen ovale or other potential intracardiac shunts are established risk factors for stroke via paradoxical embolization. Stroke is less common in children and risk factors differ. The authors examined the literature on intracardiac shunting and stroke in children, identifying the methods employed, the prevalence of detectible intracardiac shunts, associated conditions, and treatments. PubMed searches with keywords related to intracardiac shunting and stroke in children identified articles of interest. Additional articles were identified via citations in these articles or in reviews. The authors found that studies of intracardiac shunting in children with stroke are limited. No controlled studies were identified. Detection methods vary and the prevalence of echocardiographically detectible intracardiac shunting appears lower than reported in adults and autopsy studies. Defining the role of intracardiac shunting in pediatric stroke will require controlled studies with unified detection methods in populations stratified by additional risk factors for paradoxical embolization. Optimal treatment is unclear.

Wake-up test decrease shunts insertion during carotid endarterectomy under general anesthesia

OBJECTIVE

The use of locoregional anesthesia versus general anesthesia (GE) in carotid endarterectomy (CEA) has been a debatable issue in clinical studies for the past several years. In our study, GE with wake-up tests (WUTs) during carotid cross-clamping was used instead of stump pressure (SP) to directly assess the neurological status of the patient to determine whether shunting was needed. Our study assessed the percentage of patients under light sedation and mechanically ventilated needing shunting based on WUT compared to a systolic stump pressure (SPs) cutoff value of <or=40 mm Hg.

DESIGN

Retrospective, observational study.

SETTING

University hospital clinic.

PARTICIPANTS

Three hundred fifty-one patients (American Society of Anesthesiologists physical class II-III) with carotid artery stenosis scheduled for CEA under GE.

INTERVENTIONS

The WUT was used to assess the neurological status in patients undergoing CEA, which involved the gradual reduction of depth of anesthesia until the patient was capable of responding to a verbal stimulus and provide full collaboration while only receiving remifentanil. A positive WUT indicated that patient was not able to carry out the order.

MEASUREMENTS AND MAIN RESULTS

Of 343 patients, 20 (5.8%) were shunted due to a positive WUT after cross-clamping in comparison to 45 patients (12.8%) based on the SPs <or=40 mm Hg criteria.

CONCLUSION

Wake-up test can be used to directly assess the neurological status in patients undergoing CEA to determine whether shunting is required. Our results showed that less patients required shunting based on WUT compared to the SP criteria.

Anaesthetic complications associated with the treatment of patients with congenital cardiac disease: consensus definitions from the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease

Congenital heart defects are the most common cause of death in infants and young children in the developed world. As the mortality in this population has declined to less than 5%, more attention is being focused now on reducing post-procedural morbidities that may seriously impact the patient and their families. Because of multiple reasons, paediatric cardiac surgery and anaesthesia is a perfect model for studying human errors and their impact on patient safety. Congenital cardiac disease is a common lesion causing much morbidity, pain, and loss of life. Over 44,000 surgical procedures are performed yearly to repair congenital cardiac problems in the United States alone. The reduction or elimination of iatrogenic adverse outcomes, given the current mortality rates of 4.2%-4.5%, might lead to as many as 500 children achieving better outcomes or shorter hospitalizations.Efforts to quantify the frequency of complications related to anaesthesia in patients undergoing congenital cardiac surgery have been difficult to date because of the low occurrence of this surgery compared to other surgeries on children and the relatively rare incidence of complications related to anaesthesia in this population. Anaesthesiologists play a crucial role in the reduction, recognition, and timely treatment of medical errors that impact this morbidity. Paediatric cardiac surgery encompasses many complex procedures that are highly dependent upon a sophisticated organizational structure, effective communication, coordinated efforts of multiple individuals working as a team, and high levels of cognitive and technical performance. Human factor error analysis in this patient population has shown how frequently both minor and major errors occur. The goal of this paper is to outline the frequency and sources of these errors and to suggest treatment strategies which may minimize their occurrence.

Electrophysiologic monitoring in neurosurgery

Electrophysiologic techniques have become common in the neurosurgical operating room. This article reviews the methods used for mapping neural structures or monitoring during surgery. Mapping methods allow identification of target structures for surgery, or for identifying structures to allow avoidance or plot safe pathways to deeper structures. Monitoring methods allow for surgery on nearby structures to warn of encroachment, thereby reducing unwanted injury.