Neurophysiological Intraoperative Monitoring During Aortic Arch Surgery

Association of EEG and Blood-Based Brain Injury Biomarker Accuracy to Prognosticate Mortality After Pediatric Cardiac Arrest: An Exploratory Study

BACKGROUND

Evaluate the accuracy of brain-based blood biomarkers neuron-specific enolase (NSE) and S100b and electroencephalography (EEG) features alone and in combination with prognosticate 6-month mortality after pediatric cardiac arrest. We hypothesized that the combination of blood brain-based biomarkers and EEG features would have superior classification accuracy of outcome versus either alone.

METHODS

Children (n = 58) aged between 1 week and 17 years admitted to the ICU following cardiac arrest at a tertiary care children's hopital were eligible for this secondary study. Blood NSE and S100b were measured closest to 24 hours after return of spontaneous circulation (ROSC). EEGs closest to 24 hours (median 11, interquartile range [IQR] 6 to 16 h) post-ROSC were evaluated by two epileptologists. EEG grade was informed by background frequency, amplitude, and continuity. Sleep spindles were present or absent. Mortality was assessed at six months post-ROSC. Area under the receiver operator curve (AUC) was performed for individual and combined brain-based biomarkers and EEG features.

RESULTS

Children were aged 2.6 (IQR 0.6 to 10.4) years, and 25 (43%) died. Children who died had increased blood NSE (49.7 [28.0 to 63.1] vs 18.2 [9.8 to 31.8] ng/mL) and S100b (0.118 [0.036 to 0.296] vs 0.012 [0.003 to 0.021] ng/mL) and poor (discontinuous or isoelectric) EEG grade (76% vs 33%) more frequently than survivors (P < 0.05). AUC for NSE to predict mortality was 0.789, and was 0.841 when combined with EEG grade and spindles. S100b AUC for mortality was 0.856 and was optimal alone.

CONCLUSIONS

In this exploratory study, the combination of brain-based biomarkers and EEG features may provide more accurate prognostication than either test alone after pediatric cardiac arrest.

Optimal brain protection in aortic arch surgery

There is considerable debate with regard to the optimal cerebral protection strategy during aortic arch surgery. There are three contemporary techniques in use which include straight deep hypothermic circulatory arrest (DHCA), DHCA with retrograde cerebral perfusion (DHCA + RCP), and moderate hypothermic circulatory arrest with antegrade cerebral perfusion (MHCA + ACP). Appropriate application of these methods ensures appropriate cerebral, myocardial, and visceral protection. Each of these techniques has benefits and drawbacks and ensuring coordinated circulation management strategy is critical to safe performance of aortic arch surgery. In this report, we will review various cannulation strategies, review logistics of hypothermia, and review the relevant literature to outline the strengths and weaknesses of these various cerebral protection strategies.

Anaesthetic-surgical guide in the treatment of ascending aorta and surgery of the ascending aorta and aortic arch. Consensus document of the Spanish Society of Cardiovascular and Endovascular Surgery and the Sociedad of Anaesthesiology, Resuscitation and Pain Therapy

Aortic pathology is always a challenge for the clinician, and must be diagnosed and treated by a multidisciplinary team due to the technical and technological complexity of the resources used. Ongoing efforts to implement a systematic, protocolized approach involving "Aortic teams" made up of cardiologists, cardiac surgeons, vascular surgeons, anaesthesiologists and radiologists, among others are now leading to improved outcomes. The aim of this consensus document drawn up by the Aortic working groups of the Spanish Society of Anaesthesiology, Resuscitation and Pain Therapy (SEDAR) and the Spanish Society of Thoracic and Cardiovascular Surgery (SECTCV) is to disseminate a set of working protocols. The latest consensus document of the European Association for Cardio-Thoracic Surgery (EACTS) and the European Society for Vascular Surgery (ESVS) define the concept of "AORTIC TEAM"(1). The aortic team should be closely involved from diagnosis to treatment and finally follow-up, and should be formed of cardiac and vascular surgeons working together with anaesthesiologists, cardiologists, radiologists and geneticists. Treatment of aortic pathologies should be centralised in large centres, because this is the only way to effectively understand the natural course of the disease, provide the entire range of treatment options under one umbrella and treat potential complications. A streamlined emergent care pathway (24/7 availability), adequate transportation and transfer capabilities, as well as rapid activation of the multidisciplinary team must be available. In light of the complexity and constant evolution of therapeutic options, we present this first version of the Anaesthesiology and surgical guidelines for surgery of the ascending aorta and aortic arch. Some questions will no doubt remain unanswered, and future versions will include new techniques that, though implemented in some centres, are still not widely recommended.

Endovascular treatment of thoracoabdominal aortic aneurysms

Endovascular repair of thoracoabdominal aneurysms using fenestrated and/or branched stent grafts is technically feasible and efficacious but carries a steep learning curve. This innovative surgical approach is associated with less perioperative morbidity than traditional open repair and its early and mid-term outcomes are very favorable. Spinal cord ischemia remains a devastating complication after these procedures, hence the importance of various neuroprotective strategies. Widespread applicability remains limited in the United States, as no custom-made or off-the-shelf endografts are commercially available. Access to these devices remains limited to physician-sponsored or industry-sponsored clinical trials, but results from the Cook p-Branch and Gore Thoracoabdominal Branch Endoprosthesis trials are on the horizon.

Does deeper hypothermia reduce the risk of acute kidney injury after circulatory arrest for aortic arch surgery?

OBJECTIVES

The impact of hypothermic circulatory arrest (HCA) temperature on postoperative acute kidney injury (AKI) has not been evaluated. This study examined the association between circulatory arrest temperatures and AKI in patients undergoing proximal aortic surgery with HCA.

METHODS

A total of 759 consecutive patients who underwent proximal aortic surgery (ascending ± valve ± root) including arch replacement requiring HCA between July 2005 and December 2016 were identified from a prospectively maintained institutional aortic surgery database. The primary outcome was AKI as defined by Risk, Injury, Failure, Loss, End Stage Renal Disease (ESRD) criteria. The association between minimum nasopharyngeal (NP) and bladder temperatures during HCA and postoperative AKI was assessed, adjusting for patient-level factors using multivariable logistic regression.

RESULTS

A total of 85% (n = 645) of patients underwent deep hypothermia (14.1-20.0°C), 11% (n = 83) low-moderate hypothermia (20.1-24.0°C) and 4% (n = 31) high-moderate hypothermia (24.1-28.0°C) as classified by NP temperature. When analysed by bladder temperature, 59% (n = 447) underwent deep hypothermia, 22% (n = 170) low-moderate, 16% (n = 118) high-moderate and 3% mild (n = 24) (28.1-34.0°C) hypothermia. The median systemic circulatory arrest time was 17 min. The incidence of AKI did not differ between hypothermia groups, whether analysed using minimum NP or bladder temperature. In the multivariable analysis, the association between degree of hypothermia and AKI remained non-significant whether analysed as a categorical variable (hypothermia group) or as a continuous variable (minimum NP or bladder temperature) (all P > 0.05).

CONCLUSIONS

In patients undergoing proximal aortic surgery including arch replacement requiring HCA, degree of systemic hypothermia was not associated with the risk of AKI. These data suggest that moderate hypothermia does not confer increased risk of AKI for patients requiring circulatory arrest, although additional prospective data are needed.

Anaesthetic-surgical guide in the treatment of ascending aorta and surgery of the ascending aorta and aortic arch. Consensus document of the Spanish Society of Cardiovascular and Endovascular Surgery and the Sociedad of Anaesthesiology, Resuscitation and Pain Therapy

Aortic pathology is always a challenge for the clinician, and must be diagnosed and treated by a multidisciplinary team due to the technical and technological complexity of the resources used. Ongoing efforts to implement a systematic, protocolized approach involving "Aortic teams" made up of cardiologists, cardiac surgeons, vascular surgeons, anaesthesiologists and radiologists, among others are now leading to improved outcomes. The aim of this consensus document drawn up by the Aortic working groups of the Spanish Society of Anaesthesiology, Resuscitation and Pain Therapy (SEDAR) and the Spanish Society of Thoracic and Cardiovascular Surgery (SECTCV) is to disseminate a set of working protocols. The latest consensus document of the European Association for Cardio-Thoracic Surgery (EACTS) and the European Society for Vascular Surgery (ESVS) define the concept of "AORTIC TEAM"(1). The aortic team should be closely involved from diagnosis to treatment and finally follow-up, and should be formed of cardiac and vascular surgeons working together with anaesthesiologists, cardiologists, radiologists and geneticists. Treatment of aortic pathologies should be centralised in large centres, because this is the only way to effectively understand the natural course of the disease, provide the entire range of treatment options under one umbrella and treat potential complications. A streamlined emergent care pathway (24/7 availability), adequate transportation and transfer capabilities, as well as rapid activation of the multidisciplinary team must be available. In light of the complexity and constant evolution of therapeutic options, we present this first version of the Anaesthesiology and surgical guidelines for surgery of the ascending aorta and aortic arch. Some questions will no doubt remain unanswered, and future versions will include new techniques that, though implemented in some centres, are still not widely recommended.

Collateral Circulation in Spinal Cord Injury: A Comprehensive Review

Surgery is the most common cause of spinal cord ischemia; it is also caused by hemodynamic changes, which disrupt the blood flow. Direct ligation of the spinal arteries, especially the Adamkiewicz artery is involved as well. Other causes of spinal cord ischemia include arteriography procedures, thoracic surgery, epidural and rachianesthesia, foraminal infiltration, arterial dissection, systemic hypotension, emboligenic heart disease, thoracic disc herniation, and compression. Understanding the vascular anatomy of the spinal cord is essential to develop optimal strategies for preventing ischemic injuries to the spinal cord. During ischemia, a rich network of intra and paraspinal collaterals allow enough blood flow to compensate the intensity of spinal cord ischemia. In case of interruption of flow of a main artery, the collateral artery increases its flow to maintain perfusion to the tissues. Avoiding spinal cord ischemia by using collateral circulation is necessary to prevent the establishment of hypovolemia, hyperthermia and elevations in venous pressures. The objective of this narrative review is to present the current concepts of spinal collateral circulation and its role in the setting of ischemic events, affecting the vascular supply of the spinal cord.

Spinal Cord Ischemia in Pancreas Transplantation: The UK Experience

BACKGROUND

Spinal cord ischemia (SCI) is a rare but devastating condition that can occur in the perioperative period resulting in paraplegia. Although diabetes mellitus is a risk factor for SCI in other types of major surgery, SCI is not widely recognized in transplantation. The aim of this study was to quantify the risk of SCI in pancreatic transplantation.

METHODS

All UK pancreas transplant units were surveyed between 2017 and 2018. The risk of SCI in pancreas transplantation was estimated using the number of radiologically confirmed cases relative to the number of pancreatic transplants from UK registry data during the same time period.

RESULTS

There have been 6 cases of SCI during pancreas transplantation since 2002. No aortic clamping occurred in any recipient. During or after surgery, all patients experienced episodes of hypotension (systolic blood pressure ≤ 90 mm Hg) before the onset of neurological symptoms. Epoprostenol, epidural anesthesia, and postoperative hemodialysis may have contributed to systemic hypotension. The mainstay of early treatment for SCI for all cases was blood pressure control.

CONCLUSIONS

Based on these findings, there is approximately a 1:440 risk of SCI in pancreas transplantation. Hypotension appears to be a prominent risk factor. Strategies for mitigating the risk of SCI are discussed, drawing on evidence from thoraco-abdominal aortic aneurysm surgery. The risk of long-term neurological deficit should be discussed with prospective pancreas recipients given the potential impact on posttransplant quality of life.

Neuroprotective Strategies in Repair and Replacement of the Aortic Arch

Aortic arch surgery is a technical challenge, and cerebral protection during distal anastomosis is a continued topic of controversy and discussion. The physiologic effects of hypothermic arrest and adjunctive cerebral perfusion have yet to be fully defined, and the optimal strategies are still undetermined. This review highlights the historical context, physiological rationale, and clinical efficacy of various neuroprotective strategies during arch operations.

Intraoperative care for aortic surgery using circulatory arrest

The total circulatory arrest (CA) is necessary to achieve optimal surgical conditions in certain aortic pathologies, especially in those affecting the ascending aorta and aortic arch. During this procedure it is necessary to protect all the organs of ischemia, especially those of the central nervous system and for this purpose several strategies have been developed. The first and most important protective method is systemic hypothermia. The degree of hypothermia and the route of application have been evolving and currently tend to use moderate hypothermia (MH) (20.1-28 °C) associated with unilateral or bilateral selective cerebral perfusion methods. In this way the neurological results are better, the interval of security is greater and the times of extracorporeal circulation are smaller. Even so, it is necessary to take into account that there is the possibility of ischemia in the lower part of the body, especially of the abdominal viscera and the spinal cord, therefore the time of circulatory stop should be limited and not to exceed 80 minutes. Evidence of possible neurological drug protection is very weak and only mannitol, magnesium, and statins can produce some benefit. Inhalational anesthetics and some intravenous seem to have advantages, but more studies would be needed to test their long-term benefit. Other important parameters to be monitored during these procedures are blood glucose, anemia and coagulation disorders and acid-base balance. The recommended monitoring is common in complex cardiovascular procedures and it is of special importance the neurological monitoring that can be performed with several techniques, although currently the most used are Bispectral Index (BIS) and Near-Infrared Spectroscopy (NIRS). It is also essential to monitor the temperature routinely at the nasopharyngeal and bladder level and it is important to control coagulation with rotational thromboelastometry (ROTEM).

Anesthetic Considerations for Surgery on the Aortic Arch

Aortic arch surgery requires meticulous teamwork in the true perioperative sense. Planning and communication at all phases from preoperative evaluation, through intraoperative management, to postoperative care should be well coordinated between surgical, anesthesia, perfusion, and intensive care unit teams. This review discusses intraoperative management from the anesthesiologist’s perspective, with particular emphasis on transesophageal echo evaluation and coagulation management.