Spinal Cord Protection for Thoracoabdominal Aortic Surgery

Veno-arterial extracorporeal membrane oxygenation (ECMO VA) as part of a multimodal approach for the protection of spinal cord ischemia in surgical repair of a thoracoabdominal aneurysm

Spinal cord ischaemia leading to paraplegia or paraparesis is one of the most devastating complications of aortic surgery. The risk of ischaemia is particularly high in repairs involving both the thoracic and abdominal segments, because in these cases blood flow to the spinal arteries can be interrupted. Multimodal protocols have now been developed to reduce the incidence of this complication, and include measures such as cerebrospinal fluid (CSF) drainage, avoidance of hypotension and anaemia, systemic hypothermia, neuromonitoring, maintaining distal perfusion during proximal clamping of the aorta, and reimplantation of intercostal or lumbar arteries, whenever feasible. We describe a case in which, due to the special characteristics of the surgery, veno-arterial extracorporeal membrane oxygenation (VA ECMO) was used to maintain distal blood flow in the lumbar, inferior mesenteric, and hypogastric arteries during aortic clamping. This approach reduced the risk of spinal cord and visceral ischaemia, and also eliminated the need for thoracotomy because partial left bypass was not required.

Risk Factors for Spinal Cord Injury during Endovascular Repair of Thoracoabdominal Aneurysm: Review of the Literature and Proposal of a Prognostic Score

Despite recent improvements, spinal cord ischemia remains the most feared and dramatic complication following extensive aortic repair. Although endovascular procedures are associated with a lower risk compared with open procedures, this risk is still significant and must be considered. A combined medical and surgical approach may help to optimize the tolerance of the spinal cord to ischemia. The aim of this review is to describe the underlying mechanism involved in spinal cord injury during extensive endovascular aortic repair, to describe the different techniques used to improve spinal cord tolerance to ischemia-including the prophylactic or curative use of spinal drainage-and to propose our algorithm for spinal cord protection and the rational use of spinal drainage.

Highlights and Perioperative Implications from the 2022 American College of Cardiology and American Heart Association Guidelines for Diagnosis and Management of Aortic Disease

As the understanding of aortic diseases and their complications grow, increasing importance of uniformity in diagnosis and management is crucial for optimal care of this patient population. The 2022 American College of Cardiology and American Heart Association Guidelines for Diagnosis and Management of Aortic Disease discusses these considerations in detail. The purpose of this review is to highlight essential recommendations that are of relevance to the perioperative physician who manages these patients. A few notable points include, shared decision-making with patients, creation of multidisciplinary aortic teams, lower diameter thresholds for surgery in certain situations, and increased testing for patients with heritable aortic diseases. In addition to briefly reviewing basics of aortic diseases, the authors discuss changes to guidelines that are especially relevant to perioperative care.

Practice of neuromonitoring in open and endovascular thoracoabdominal aortic repair-an international expert-based modified Delphi consensus study

OBJECTIVES

Spinal cord injury is detrimental for patients undergoing open or endovascular thoracoabdominal aortic aneurysm (TAAA) repair. The aim of this survey and of the modified Delphi consensus was to gather information on current practices and standards in neuroprotection in patients undergoing open and endovascular TAAA.

METHODS

The Aortic Association conducted an international online survey on neuromonitoring in open and endovascular TAAA repair. In a first round an expert panel put together a survey on different aspects of neuromonitoring. Based on the answers from the first round of the survey, 18 Delphi consensus questions were formulated.

RESULTS

A total of 56 physicians completed the survey. Of these, 45 perform open and endovascular TAAA repair, 3 do open TAAA repair and 8 do endovascular TAAA repair. At least 1 neuromonitoring or protection modality is utilized during open TAAA surgery. Cerebrospinal fluid (CSF) drainage was used in 97.9%, near infrared spectroscopy in 70.8% and motor evoked potentials or somatosensory evoked potentials in 60.4%. Three of 53 centres do not utilize any form of neuromonitoring or protection during endovascular TAAA repair: 92.5% use CSF drainage; 35.8%, cerebral or paravertebral near infrared spectroscopy; and 24.5% motor evoked potentials or somatosensory evoked potentials. The utilization of CSF drainage and neuromonitoring varies depending on the extent of the TAAA repair.

CONCLUSIONS

The results of this survey and of the Delphi consensus show that there is broad consensus on the importance of protecting the spinal cord to avoid spinal cord injury in patients undergoing open TAAA repair. Those measures are less frequently utilized in patients undergoing endovascular TAAA repair but should be considered, especially in patients who require extensive coverage of the thoracoabdominal aorta.

Anaesthesia for vascular emergencies - a state of the art review

In this state-of-the-art review, we discuss the presenting symptoms and management strategies for vascular emergencies. Although vascular emergencies are best treated at a vascular surgical centre, patients may present to any emergency department and may require both immediate management and safe transport to a vascular centre. We describe the surgical and anaesthetic considerations for management of aortic dissection, aortic rupture, carotid endarterectomy, acute limb ischaemia and mesenteric ischaemia. Important issues to consider in aortic dissection are extent of the dissection and surgical need for bypasses in addition to endovascular repair. From an anaesthetist's perspective, aortic dissection requires infrastructure for massive transfusion, smooth management should an endovascular procedure require conversion to an open procedure, haemodynamic manipulation during stent deployment and prevention of spinal cord ischaemia. Principles in management of aortic rupture, whether open or endovascular treatment is chosen, include immediate transfer to a vascular care centre; minimising haemodynamic changes to reduce aortic shear stress; permissive hypotension in the pre-operative period; and initiation of massive transfusion protocol. Carotid endarterectomy for carotid stenosis is managed with general or regional techniques, and anaesthetists must be prepared to manage haemodynamic, neurological and airway issues peri-operatively. Acute limb ischaemia is a result of embolism, thrombosis, dissection or trauma, and may be treated with open repair or embolectomy, under either general or local anaesthesia. Due to hypercoagulability, there may be higher numbers of acutely ischaemic limbs among patients with COVID-19, which is important to consider in the current pandemic. Mesenteric ischaemia is a rare vascular emergency, but it is challenging to diagnose and associated with high morbidity and mortality. Several peri-operative issues are common to all vascular emergencies: acute renal injury; management of transfusion; need for heparinisation and reversal; and challenging postoperative care. Finally, the important development of endovascular techniques for repair in many vascular emergencies has improved care, and the availability of transoesophageal echocardiography has improved monitoring as well as aids in surgical placement of endovascular grafts and for post-procedural evaluation.

Novel method for direct retransfusion reduces blood transfusions in descending and thoracoabdominal aneurysm repair

BACKGROUND

Allogenic blood product usage is associated with worse outcomes in open repair of descending and thoracoabdominal aortic aneurysms. This pilot study evaluated the safety and efficacy of a novel modification of the left heart bypass (LHB) circuit to reduce intraoperative blood transfusions.

METHODS

In modified LHB, pump suckers collected shed blood that was directly retransfused through a femoral vein cannula. In standard LHB, cellsavers were used to collect, wash, and retransfuse shed blood. Consecutive patients undergoing elective surgical descending or thoracoabdominal aneurysm repair using modified (N.=12) or standard (N.=21) LHB were compared. Intraoperative blood product use was the primary outcome. Hypotensive episodes, lactate levels, and adverse events (early mortality, spinal cord injury, renal and respiratory insufficiency) were secondary outcomes.

RESULTS

Groups were comparable regarding pre- and intraoperative variables. No perfusion-related adverse events occurred. With modified LHB, intraoperative blood product use was significantly reduced: packed red blood cells by 60% from 10 to 4 units (P=0.002), fresh frozen plasma by 70% from 17 to 5 units (P<0.001) as well as retransfused cellsaver volume by 75%, from 4500 mL to 1110 mL (P<0.001). Hemodynamic instability occurred in 1 (8.3%) vs. 6 (29%), P=0.22 and overall lactate levels were significantly reduced (P=0.045) with modified LHB. Adverse events combined occurred in 1/12 vs. (P=0.022).

CONCLUSIONS

The novel modified LHB with direct retransfusion was safe and associated with significantly reduced intraoperative blood product use, reduced lactate production and improved clinical outcomes as compared to standard LHB and could represent an important clinical improvement.

Distal aortic replacement followed by endovascular repair for the management of severe intra-pleural adhesions accidentally detected during open surgery for chronic type B aortic dissection: a report of two cases

BACKGROUND

Open repair is the most promising curative treatment option for patients with chronic type B aortic dissection. However, based on our experience, following the accidental detection of intra-pleural adhesions during open surgery for chronic type B aortic dissection, complete replacement of the diseased aorta cannot be accomplished. To overcome this problem, we switched the procedure to create a distal landing zone for subsequent endovascular repair by replacing the distal aorta with a vascular graft.

CASE PRESENTATION

We report two cases in which open repair was attempted; however, the proximal descending thoracic aorta could not be exposed due to the presence of severe adhesion in the pleural cavity. In these patients, we accessed the lower descending thoracic aorta or thoracoabdominal aorta and created a distal landing zone for subsequent endovascular repair by replacing the aorta with a vascular graft. Thereafter, endovascular repair was performed with good outcomes.

CONCLUSIONS

Replacement of the distal aorta, which is typically easy to access despite the presence of intra-pleural adhesions, with a vascular graft serves as a reliable distal landing zone for subsequent endovascular repair. This method may be a viable option for the management of severe adhesions accidentally detected in the pleural cavity during open repair for chronic type B aortic dissection.

Postoperative Intensive Care Management of Aortic Repair

Vascular surgery patients have multiple comorbidities and are at high risk for perioperative complications. Aortic repair surgery has greatly evolved in recent years, with an increasing predominance of endovascular techniques (EVAR). The incidence of cardiac complications is significantly reduced with endovascular repair, but high-risk patients require postoperative ST-segment monitoring. Open aortic repair may portend a prohibitive risk of respiratory complications that could be a contraindication for surgery. This risk is greatly reduced in the case of an endovascular approach, and general anesthesia should be avoided whenever possible in the case of endovascular repair. Preoperative renal function and postoperative kidney injury are powerful determinants of short- and long-term outcome, so that preoperative risk stratification and secondary prevention are critical tasks. Intraoperative renal protection with selective renal and distal aortic perfusion is essential during open repair. EVAR has lower rates of postoperative renal failure compared to open repair, with approximately half the risk for acute kidney injury (AKI) and one-third of the risk of hemodialysis requirement. Spinal cord ischemia used to be the most distinctive and feared complication of aortic repair. The risk has significantly decreased since the beginning of aortic surgery, with advances in surgical technique and spinal protection protocols, and is lower with endovascular repair. Endovascular repair avoids extensive aortic dissection and aortic cross-clamping and is generally associated with reduced blood loss and less coagulopathy. The intensive care physician must be aware that aortic repair surgery has an impact on every organ system, and the importance of early recognition of organ failure cannot be overemphasized.