Lumbar Cerebrospinal Fluid Drainage for Thoracoabdominal Aortic Surgery

Spinal cord injury after thoracic endovascular aortic aneurysm repair

PURPOSE

Thoracic endovascular aortic aneurysm repair (TEVAR) has become a mainstay of therapy for aneurysms and other disorders of the thoracic aorta. The purpose of this narrative review article is to summarize the current literature on the risk factors for and pathophysiology of spinal cord injury (SCI) following TEVAR, and to discuss various intraoperative monitoring and treatment strategies.

SOURCE

The articles considered in this review were identified through PubMed using the following search terms: thoracic aortic aneurysm, TEVAR, paralysis+TEVAR, risk factors+TEVAR, spinal cord ischemia+TEVAR, neuromonitoring+thoracic aortic aneurysm, spinal drain, cerebrospinal fluid drainage, treatment of spinal cord ischemia.

PRINCIPAL FINDINGS

Spinal cord injury continues to be a challenging complication after TEVAR. Its incidence after TEVAR is not significantly reduced when compared with open thoracoabdominal aortic aneurysm repair. Nevertheless, compared with open procedures, delayed paralysis/paresis is the predominant presentation of SCI after TEVAR. The pathophysiology of SCI is complex and not fully understood, though the evolving concept of the importance of the spinal cord's collateral blood supply network and its imbalance after TEVAR is emerging as a leading factor in the development of SCI. Cerebrospinal fluid drainage, optimal blood pressure management, and newer surgical techniques are important components of the most up-to-date strategies for spinal cord protection.

CONCLUSION

Further experimental and clinical research is needed to aid in the discovery of novel neuroprotective strategies for the protection and treatment of SCI following TEVAR.

The myocardial protective effect of dexmedetomidine in high-risk patients undergoing aortic vascular surgery

Objective:

The aim of the study was to assess the effect of dexmedetomidine in high-risk patients undergoing aortic vascular surgery.

Design:

A randomized prospective study.

Setting:

Cairo University, Egypt.

Materials and Methods:

The study included 150 patients undergoing aortic vascular surgery.

Intervention:

The patients were classified into two groups (n = 75). Group D: The patients received a loading dose of 1 μg/kg dexmedetomidine over 15 min before induction and maintained as an infusion of 0.3 μg/kg/h to the end of the procedure. Group C: The patients received an equal volume of normal saline. The medication was prepared by the nursing staff and given to anesthetist blindly.

Measurements:

The monitors included the heart rate, mean arterial blood pressure, central venous pressure, electrocardiogram (ECG), serum troponin I level, end-tidal sevoflurane, and total dose of morphine in addition transthoracic echocardiography to the postoperative in cases with elevated serum troponin I level.

Main Results:

The dexmedetomidine decreased heart rate and minimized the changes in blood pressure compared to control group (P < 0.05). Furthermore, it decreased the incidence of myocardial ischemia reflected by troponin I level, ECG changes, and the development of new regional wall motion abnormalities (P < 0.05). Dexmedetomidine decreased the requirement for nitroglycerin and norepinephrine compared to control group (P < 0.05). The incidence of hypotension and bradycardia was significantly higher with dexmedetomidine (P < 0.05).

Conclusion:

The dexmedetomidine is safe and effective in patients undergoing aortic vascular surgery. It decreases the changes in heart rate and blood pressure during the procedures. It provides cardiac protection in high-risk patients reflected by decreasing the incidence of myocardial ischemia and serum level of troponin. The main side effects of dexmedetomidine were hypotension and bradycardia.

Subacute post-traumatic ascending myelopathy after T12 burst fracture in a 32-year-old male: case report and surgical result of cervical durotomy

To draw attention to a rare neurological deterioration after spinal cord injury (SCI) and to discuss evidence supporting an increase in cerebrospinal fluid pressure (CSFP), we present an extremely rare case of subacute post-traumatic ascending myelopathy (SPAM) in which the patient sustained a T12 fracture initially resulting in paraplegia and after undergoing posterior fixation and anterior decompression. The patient was a 32-year-old healthy man who sustained a T12 burst fracture with complete paraplegia after a fall injury. The patient underwent a posterior reduction and short-segment fixation 8 h after the injury and an anterior thoracoscopic-assisted decompression on post-traumatic day 8. On post-traumatic day 21, he had a progressive neurological deterioration with dyspnoea and decreased muscle strength of both upper extremities that could not be relieved by conservative intervention. After undergoing a cervical posterior laminectomy and durotomy, the patient exhibited the clinical manifestation of brain herniation. There was no recovery of autonomous respiration, and the patient entered a coma. The patient died on post-traumatic day 25 because of cardiac and respiratory arrest. SPAM is a rare, potentially fatal neurological deterioration after SCI; however, a prompt diagnosis can be made by magnetic resonance imaging. Our observations suggest that an increase in CSFP may be the main cause of SPAM. The paraplegic level should be recorded daily so that neurological deterioration can be recognised as soon as possible.

Subacute posttraumatic ascending myelopathy: a literature review

Study design:

A literature review.

Objectives:

Our aim was to summarise the history, epidemiology, aetiological mechanism, pathological study, clinical and radiological evaluation, treatment and prognosis of subacute posttraumatic ascending myelopathy (SPAM).

Methods:

Medical literature on SPAM were searched in the PubMed, Medline, Ovid and Embase databases. The cases of SPAM reported in literature were analysed, and the history, epidemiology, aetiological mechanism, pathological study, clinical and radiological evaluation, treatment and prognosis of SPAM were summarised.

Results:

SPAM remains a relatively rare disorder occurring within the first few weeks after spinal cord injury (SCI). The incidence rate ranges from 0.42% to 1% among all SCI. SPAM is likely to occur in young and middle-aged male patients. Risk factors of SPAM include complete injury, low blood pressure, early postoperative mobilisation and nonsurgical treatment.

Conclusions:

SPAM is well recognised according to typical clinical manifestation and magnetic resonance imaging characteristics. There is no effective therapy for this neurological deterioration. The prognosis of SPAM is poor. There is usually a slight improvement of one or more level(s) below the maximal level of deterioration. The mortality rate is approximately 10%.

Moderate hypothermia increased the incidence of delayed paralysis through activation of the spinal microglia in an aortic cross-clamping rat model

BACKGROUND

Hypothermia reduces immediate paralysis during surgical repair of aortic aneurysms. However, it is unknown what the impact of hypothermia is on delayed paralysis, a serious complication of this type of surgery.

METHODS

Sprague-Dawley rats were subjected to occlusion of the descending aorta at different duration under normothermia (38.0±0.5) or hypothermia (33.0±0.5°). Neurologic function was assessed. Motor neuron number, glial activation, and cytokine expression in the spinal cord were examined. Minocycline was administered perioperatively by intraperitoneal injection in the rats subjected to the aorta occlusion.

RESULTS

In contrast to normothermia conditions at which immediate paralysis occurred when the duration of aorta occlusion exceeded 11.5min, hypothermia did not induce immediate paralysis if the duration of aorta occlusion was less than 41min. However, delayed paralysis was developed when the duration of aorta occlusion exceeded 18min, and reached peak level when the duration of aorta occlusion was 40min at hypothermia condition. The number of motoneurons was significantly decreased (P<0.05) at 30h postoperation. In addition, microglia was activated, and interleukin-1β and interleukin-6 levels were upregulated, both of which were co-localized in microglia at 24h postoperation in the hypothermia group. Minocycline treatment attenuated the incidence and degree of paralysis but did not decrease the mortality.

CONCLUSIONS

Hypothermia, a neuroprotective strategy in cardiothoracic surgery, increased the incidence of delayed paralysis through activation of spinal microglia and cytokines. Blocking the activated microglia may be a potential intervention to prevent the incidence of delayed paralysis.

Strategies to prevent TEVAR-related spinal cord ischemia

Spinal cord ischemia remains the Achilles’ heel of thoracic and thoracoabdominal diseases management. Great improvements in morbidity and mortality have been obtained with the endovascular approach TEVAR (Thoracic Endovascular Aortic Repair) but this devastating complication continues to severely affect the quality of life, even if the primary success of the procedure – dissection/aneurysm exclusion – has been achieved.

Several strategies to deal with this complication have been published in the literature over the time. Knowledge and technology have been evolving from identification of the risk factors associated with spinal cord ischemia, including lessons learned from open surgery, and from developments in the collateral network concept for spinal cord perfusion.

In this comprehensive review, the authors cover several topics from the traditional measures comprising haemodynamic control, cerebrospinal drainage and neuroprotective drugs, to the staged-procedures approach, the emerging MISACE (minimally invasive selective segmental artery coil-embolization) and innovative neurologic monitoring such as NIRS (near-infrared spectroscopy) of the collateral network.

Intrathecal decompression versus epidural decompression in the treatment of severe spinal cord injury in rat model: a randomized, controlled preclinical research

Background

In the setting of severe spinal cord injury (SCI), there is no markedly efficacious clinical therapeutic regimen to improve neurological function. After epidural decompression, as is shown in animal models, the swollen cord against non-elastic dura and elevation of intrathecal pressure may be the main causes of aggravated neurologic function. We performed an intrathecal decompression by longitudinal durotomy to evaluate the neuroprotective effect after severe SCI by comparing with epidural decompression.

Methods

Eighty-four adult male Sprague-Dawley rats were assigned to three groups: sham group (group S), epidural decompression (group C), and intrathecal decompression group (group D). A weight-drop model was performed at T9. The Basso-Beattie-Bresnahan (BBB) score was used to evaluate neurological function. Animals were sacrificed at corresponding time points, and we performed pathohistological examinations including HE staining and immunohistochemical staining (IHC) of glial fibrillary acidic protein (GFAP), neurocan, and ED1 at the epicenter of injured cords. Finally, the lesions were quantitatively analyzed by SPSS 22.0.

Results

The mortality rates were, respectively, 5.55 % (2/36) and 13.9 % (5/36) in groups C and D, and there was no significant difference between groups C and D (P = 0.214). Compared with epidural decompression, intrathecal decompression could obviously improve BBB scores after SCI. HE staining indicated that more white matter was spared, and fewer vacuoles and less axon degradation were observed. The expression peak of GFAP, neurocan, and ED1 occurred at an earlier time and was down-regulated in group D compared to group C.

Conclusions

Our findings based on rat SCI model suggest that intrathecal decompression by longitudinal durotomy can prompt recovery of neurological function, and this neuroprotective mechanism may be related to the down-regulation of GFAP, neurocan, and ED1.

Extended Motor Evoked Potentials Monitoring Helps Prevent Delayed Paraplegia After Aortic Surgery

OBJECTIVE

Motor evoked potentials (MEPs) monitoring can promptly detect spinal cord ischemia (SCI) from aortic clamping during open thoracoabdominal aneurysm repair (OTAAR) with distal aortic perfusion (DAP) and thus help decrease the risk of immediate postoperative SCI (IP-SCI). However, neither stable MEPs during aortic clamp interval (ACI) nor absence of IP-SCI eliminate the possibility of delayed postoperative SCI (DP-SCI). We hypothesized that extension of MEPs monitoring beyond ACI can also help decrease the risk of DP-SCI.

METHODS

We identified 150 consecutive patients at our institution between April 2005 and October 2014 who underwent OTAAR with DAP and MEPs monitoring and had no IP-SCI. Using logistic regression analysis, we studied the independent effect of extended MEPs monitoring on the risk of developing DP-SCI. We used a propensity score analysis to adjust for potential confounders, such as poorly controlled hypertension, previous aneurysm surgery, splenectomy, acute aortic dissection, aneurysm type, older age, and history of diabetes and smoking.

RESULTS

From the 150 patients, 129 (86%) remained neurologically intact whereas 21 (14%) developed DP-SCI. Nineteen of these twenty-one patients (90%) had no extended monitoring. Fifty-seven of fifty-nine (97%) patients who benefited from extended monitoring had no DP-SCI (p = 0.003). Extended MEPs monitoring was independently associated with decreased risk of DP-SCI (odds ratio = 0.14; 95% confidence interval: 0.03, 0.65; p = 0.01).

INTERPRETATION

MEPs detect the lowest systemic blood pressure that ensures appropriate spinal cord perfusion in the postoperative period. Thus, they inform the hemodynamic management of patients post-OTAAR, particularly in the absence of a reliable neurological exam.

Midterm Outcomes of Open Descending Thoracic Aortic Repair in More Than 5,000 Medicare Patients

BACKGROUND

Diseases involving the descending thoracic aorta (DTA) represent a heterogeneous substrate with a variety of therapeutic options. Although thoracic endovascular aortic repair has been increasingly applied to DTA disease, open surgical repair is ostensibly more durable.

METHODS

A total of 5,578 patients who underwent open DTA repair (Current Procedural Terminology code 33875) from 1999 to 2010 were identified from the Medicare database; 5,489 patients had complete data. Survival was assessed with Kaplan-Meier analysis. Cox regression determined predictors of death. Hospital and surgeon volume and variability were modeled, and their association with survival assessed.

RESULTS

Median survival after open DTA repair was only 4.3 years (95% confidence interval: 4.0 to 4.6). The likelihood of death varied significantly by certain aortic diseases: aortic rupture and acute aortic dissection patients had the highest early mortality. Survival beyond 180 days was best for patients with acute aortic dissection and isolated thoracic aortic aneurysm, and lowest for patients with thoracoabdominal aneurysm and aortic rupture. Hospital and surgeon volume, as well as interhospital and intersurgeon variability, had associations with overall survival.

CONCLUSIONS

Open DTA repair has treated a spectrum of aortic diseases in Medicare beneficiaries. Overall mortality was high, predominately confined to the initial postoperative hazard phase. Independent hospital and surgeon effects, hospital and surgeon volume, and a more recent date of surgery correlated with improved survival, while increased operative urgency and complexity correlated with worse outcomes. These observations argue for regionalization of DTA treatment for Medicare patients in specialized centers to concentrate expertise, which should translate into better outcomes.

Rotational Thromboelastometry-Guided Hemostatic Therapy for Management of Cerebrospinal Fluid Catheter in Patients Undergoing Endovascular Aortic Repair

OBJECTIVE

Central neuraxial techniques are typically avoided in patients with underlying coagulopathy or abnormal coagulation tests. Vertebral canal hematoma is a rare but devastating complication of those procedures. Although the sensitivity and specificity of standard laboratory tests in predicting this event are rather poor or unknown, these tests are commonly used to allow or advise against the insertion of an epidural or spinal catheter. Furthermore, the role of viscoelastic point-of-care tests, which are widely used to monitor coagulation in the perioperative setting, is unexplored.

CASE REPORT

We report a patient presenting for endovascular repair of a dissecting thoracoabdominal aortic aneurysm, in which we placed a subarachnoid catheter for continuous cerebrospinal fluid drainage because of the high risk of spinal cord ischemia associated with the procedure. Unfortunately, the patient presented with an overt consumption coagulopathy that would have advised against performing any central neuraxial technique. Bedside monitoring, diagnosis, and goal-directed hemostatic therapy guided by thromboelastometry documented improved coagulation both at the time of insertion and removal of the subarachnoid device. No catheter-related complications occurred.

CONCLUSIONS

Thromboelastometry proved useful to guide hemostatic therapy before subarachnoid catheter placement and extraction in a patient with severe coagulopathy when standard coagulation tests were of less benefit.

Physical characteristics of catheters used for subarachnoid drainage

Background

Cerebrospinal fluid diversion through lumbar drainage catheters is a routine procedure that is used in a variety of clinical applications. Fracture of catheters during insertion or removal may result in retained foreign bodies that may lead to patient morbidity with potential legal ramifications. Fracture resistance is an important component of drain selection.

Objective

To analyze catheter integrity to determine which commercially available catheters are most robust and resistant to fracture.

Methods

Physical properties of the commercially available drainage catheters that can be advanced through a Touhy needle were assessed using laboratory equipment and reported. Five types of catheter were analyzed for break load, tensile strength, extension at break, and shear strength.

Results and conclusions

Of the five types of catheter, the Arrow catheter showed the greatest resistance to fracture. Of the drainage catheters, the Codman catheter showed the greatest resistance to fracture.

Management of acute traumatic spinal cord injury

OPINION STATEMENT

Spinal cord injury (SCI) causes significant morbidity and mortality. Clinical management in the acute setting needs to occur in the intensive care unit in order to identify, prevent, and treat secondary insults from local ischemia, hypotension, hypoxia, and inflammation. Maintenance of adequate perfusion and oxygenation is quintessential and a mean arterial pressure >85-90 mm Hg should be kept for at least 1 week. A cervical collar and full spinal precautions (log-roll, flat, holding C-spine) should be maintained until the spinal column has been fully evaluated by a spine surgeon. In patients with SCI, there is a high incidence of other bodily injuries, and there should be a low threshold to assess for visceral, pelvic, and long bone injuries. Computed tomography of the spine is superior to plain films, as the former rarely misses fractures, though caution needs to be exerted as occipitocervical dislocation can still be missed. To reliably assess the spinal neural elements, soft tissues, and ligamentous structures, magnetic resonance imaging is indicated and should be obtained within 48-72 h from the time of injury. All patients should be graded daily using the American Spinal Injury Association classification, with the first prognostic score at 72 h postinjury. Patients with high cervical cord (C4 or higher) injury should be intubated immediately, and those with lower cord injuries should be evaluated on a case-by-case basis. However, in the acute setting, respiratory mechanics will be disrupted with any spinal cord lesion above T11. Steroids have become extremely controversial, and the professional societies for neurosurgery in the United States have given a level 1 statement against their use in all patients. We, therefore, do not advocate for them at this time. With every SCI, a spine surgeon must be consulted to discuss operative vs nonoperative management strategies. Indications for surgery include a partial or progressive neurologic deficit, instability of the spine not allowing for mobilization, correction of a deformity, and prevention of potential neurologic compromise. Measures to prevent pulmonary emboli from deep venous thromboembolisms are necessary: IVC filters are recommended in bedbound patients and low-molecular weight heparins are superior to unfractionated heparin. Robust prevention of pressure ulcers as well as nutritional support should be a mainstay of treatment. Lastly, it is important to note that neurologic recovery is a several-year process. The most recovery occurs in the first year following injury, and therefore aggressive rehabilitation is crucial.

Migrating lumbar intrathecal catheter fragment associated with intracranial subarachnoid hemorrhage

Intrathecal catheter placement into the lumbar cistern has varied indications, including drug delivery and CSF diversion. These Silastic catheters are elastic and durable; however, catheter-associated malfunctions are well reported in the literature. Fractured catheters are managed with some variability, but entirely intradural retained fragments are often managed conservatively with observation.

The authors describe a case of a 70-year-old man with an implanted intrathecal morphine pump for failed back surgery syndrome who presented to an outside hospital with a history of headache, neck pain, nausea, and photophobia of 3 days' duration. He also described mild weakness and intermittent numbness of both legs. Unenhanced head CT demonstrated subarachnoid hemorrhage (SAH). A right C-5 hemilaminectomy was performed.

This case is unique in that there was no indication that the lumbar intrathecal catheter had fractured prior to the patient's presentation with SAH. This case demonstrates that intrathecal catheter fragments are mobile and can precipitate intracranial morbidity. Extrication of known fragments is safe and should be attempted to prevent further neurosurgical morbidity.

Spinal cord ischemia resulting in paraplegia following extrapleural pneumonectomy

A patient undergoing radical extrapleural pneumonectomy for epithelioid malignant mesothelioma developed acute paraplegia postoperatively related to long-segment spinal cord ischemia. The usual area of concern for this complication is the T9 to T12 area where the artery of Adamkiewicz is most likely to originate. In this patient, there was ligation of only upper thoracic, ipsilateral segmental arteries from the T3 to T6 level, yet he still developed paraplegia. Our hypothesis is variant mid-thoracic vascular anatomy. Previously unreported, to our knowledge, this should be understood as a rare complication of this surgery.

Results of using cardiopulmonary bypass for spinal cord protection during surgical repair of complex aortic coarctation

BACKGROUND

The aim of this study was to evaluate the surgical treatment of complex aortic coarctation using partial cardiopulmonary bypass to increase the spinal cord protection.

METHODS

A total of 15 patients (age range from 7 to 48 years) underwent coarctation repair through a left posterolateral thoracotomy with cardiopulmonary bypass. Cannulation was performed via the descending aorta and the main pulmonary artery. In all, six surgeries were performed under hypothermic circulatory arrest and nine repairs were performed under mild hypothermia. The clinical outcome regarding the development of restenosis, as well as major neurologic complication, was studied.

RESULTS

There was no mortality. None of the patients developed paraplegia. Of the 15 patients, two developed a recurrent stenosis at the proximal anastomosis between the aortic arch and the aortic prothesis at a mean follow-up of 5.5 years. In the remaining 13 patients, echocardiography and magnetic resonance imaging showed no evidence of a significant gradient.

CONCLUSION

Complex aortic coarctation without hypoplasia of the proximal aortic arch and intra-cardiac anomalies can be repaired with low mortality and neurologic morbidity via a left thoracotomy using cardiopulmonary bypass. The use of cardiopulmonary bypass goes along with a low risk of spinal cord and lower body ischaemia and provides a sufficient amount of time for the anastomoses.

Severe hypotension related to high negative pressure suction drainage on a thoracic epidural drain during multilevel spinal fixation

Hypotension or bradycardia or both related to intracranial hypotension after craniotomy has been reported in the literature. However, such reports are uncommon with thoracic epidural drains. We describe a case in which application of high negative pressure suction to a thoracic epidural drain caused a sudden decrease in arterial blood pressure.

Thoracic aortic frontier: review of current applications and directions of thoracic endovascular aortic repair (TEVAR)

Thoracic endovascular aortic repair, a minimally invasive technique is replacing the maximally invasive gold standard of thoracotomy and replacement of the descending thoracic aorta. With experience, indications have expanded to encroach on the arch and even ascending aorta. This review highlights the current state of technology, discusses controversies, and takes the perspective of a forward-thinking review to describe novel, innovative techniques that might make the entire thoracic aorta amenable to minimally invasive repair.

Complications to Cerebrospinal Fluid Drainage and Predictors of Spinal Cord Ischemia in Patients With Aortic Disease Undergoing Advanced Endovascular Therapy

Objective:

To study the complications after cerebrospinal fluid (CSF) drainage and predictors of spinal cord ischemia (SCI) after advanced endovascular therapy with CSF drainage for complex aortic disease.

Methods:

Between 2009 and 2012, 88 attempts of CSF drainage insertions/84 operations/83 patients, of the 658 operations for aortoiliac diseases, were performed.

Results:

Indications for therapy were aortic dissection (n = 13) and aortic aneurysm (n = 70), of whom 38 had thoracoabdominal aortic aneurysm (TAAA). In all, 10 had ruptured aorta. The CSF drainages were inserted preoperatively (n = 75) and postoperatively (n = 9). In all, 14 CSF drainages were nonfunctioning. The SCI was present in 29 patients, transient/permanent in 12/17. Intraoperative circulatory instability ( P = .001) and operation for TAAA, type II ( P = .036), were associated with SCI. Meningitis (n = 1), epidural (n = 1), and subdural (n = 2) hematoma and needle-mediated paresis in 1 leg (n = 1) occurred after CSF drainage.

Conclusions:

Complication to CSF drainage occurred too frequently in this selected group of patients with high rate of SCI.

Thoracic endovascular aortic repair: update on indications and guidelines

Thoracic endovascular aortic repair (TEVAR) has revolutionized thoracic aortic surgery and has increased the options available to the aortic specialist in treating thoracic aortic disease. TEVAR is less invasive, and is associated with a decrease in perioperative morbidity and mortality when compared with open surgical repair. The dramatic expansion of TEVAR activity has necessitated a better definition for the indications, contraindications, and limitations of this new technology. Ideally TEVAR should be performed in specialized aortic centers providing a full range of diagnostic and treatment options, using a multidisciplinary team approach.

Rat model of spinal cord injury preserving dura mater integrity and allowing measurements of cerebrospinal fluid pressure and spinal cord blood flow

PURPOSES

Cerebrospinal fluid (CSF) pressure elevation may worsen spinal cord ischaemia after spinal cord injury (SCI). We developed a rat model to investigate relationships between CSF pressure and spinal cord blood flow (SCBF).

METHODS

Male Wistar rats had SCI induced at Th10 (n = 7) or a sham operation (n = 10). SCBF was measured using laser-Doppler and CSF pressure via a sacral catheter. Dural integrity was assessed using subdural methylene-blue injection (n = 5) and myelography (n = 5).

RESULTS

The SCI group had significantly lower SCBF (p < 0.0001) and higher CSF pressure (p < 0.0001) values compared to the sham-operated group. Sixty minutes after SCI or sham operation, CSF pressure was 8.6 ± 0.4 mmHg in the SCI group versus 5.5 ± 0.5 mmHg in the sham-operated group. No dural tears were found after SCI.

CONCLUSION

Our rat model allows SCBF and CSF pressure measurements after induced SCI. After SCI, CSF pressure significantly increases.

[Anesthesia in the surgical repair of thoracoabdominal aneurysms: 17 years experience]

OBJECTIVE

To review the results after thoracoabdominal aortic aneurysms repair performed by the same team of surgeons and anesthesiologists over a 17 year period.

MATERIAL AND METHODS

A prospective and observational study carried out on 65 patients (97% male) who were operated on from 1995 until July 2011 for thoracoabdominal aneurysm, Crawford type i 5 (7.6%), ii 22 (33.8%), iii 17 (26.11%) and iv 21 (32.31%).

RESULTS

The 30-day mortality was 9.2% (6/65 patients), which was the same as the incidence of paraplegia. This complication only occurred in the Crawford types ii and iii aneurysms. Paraplegia was present in 4.5% (1/22) of patients in whom "left bypass" was used, compared with 29% (5/17) in which the intervention was performed by cross-clamping without distal aortic perfusion (P=.068). The most frequent complication was respiratory, with prolonged mechanical ventilation (>48h) in 20% (13 patients) of cases. The mean hospital stay was 28 days (7-92).

DISCUSSION

The average mortality in referral centers is 9.7%, ranging between 5% and 16%. In other centres the mortality at 30 days is between 19% and 31% per year. Our group had a 9.2% of mortality rate at 30 days. The incidence of paraplegia in hospitals with greater experience ranges between 2.7% and 16%. Nowadays, an incidence of less than 10% is accepted as good. We had 9.2%. The use of CSF drainage in these patients, as well as the use of left bypass and moderate hypothermia in the Crawford types i, ii and iii appear to be acceptable for prophylaxis of paraplegia.

Tranexamic acid concentrations associated with human seizures inhibit glycine receptors

Antifibrinolytic drugs are widely used to reduce blood loss during surgery. One serious adverse effect of these drugs is convulsive seizures; however, the mechanisms underlying such seizures remain poorly understood. The antifibrinolytic drugs tranexamic acid (TXA) and ε-aminocaproic acid (EACA) are structurally similar to the inhibitory neurotransmitter glycine. Since reduced function of glycine receptors causes seizures, we hypothesized that TXA and EACA inhibit the activity of glycine receptors. Here we demonstrate that TXA and EACA are competitive antagonists of glycine receptors in mice. We also showed that the general anesthetic isoflurane, and to a lesser extent propofol, reverses TXA inhibition of glycine receptor-mediated current, suggesting that these drugs could potentially be used to treat TXA-induced seizures. Finally, we measured the concentration of TXA in the cerebrospinal fluid (CSF) of patients undergoing major cardiovascular surgery. Surprisingly, peak TXA concentration in the CSF occurred after termination of drug infusion and in one patient coincided with the onset of seizures. Collectively, these results show that concentrations of TXA equivalent to those measured in the CSF of patients inhibited glycine receptors. Furthermore, isoflurane or propofol may prevent or reverse TXA-induced seizures.

The pressure distribution of cerebrospinal fluid responds to residual compression and decompression in an animal model of acute spinal cord injury

STUDY DESIGN

In vivo large animal (pig) model study of cerebrospinal fluid (CSF) pressures after acute experimental spinal cord injury (SCI).

OBJECTIVE

To determine how the CSF pressure (CSFP) and CSF pulse pressure amplitude (CSFPPA) cranial and caudal to the injury site change after an acute SCI with subsequent thecal occlusion and decompression.

SUMMARY OF BACKGROUND DATA

Lowering intrathecal pressure via CSF drainage is currently instituted to prevent ischemia-induced SCI during thoracoabdominal aortic aneurysm surgery and was recently investigated as a potential intervention for acute traumatic SCI. However, in SCI patients, persistent extradural compression commonly occludes the subarachnoid space. This may generate a CSFP differential across the injury site, which cannot be appreciated with lumbar catheter pressure measurements.

METHODS

Anesthetized pigs were subjected to an acute contusive SCI at T11 and 8 hours of sustained compression (n = 12), or sham surgery (n = 2). CSFP was measured cranial and caudal to the injury site, using miniature pressure transducers, during compression and for 6 hours after decompression.

RESULTS

The cranial-caudal CSFP differential increased (mean, 0.39 mm Hg/h), predominantly due to increased cranial pressure. On decompression, cranial CSFP decreased (mean, -1.16 mm Hg) and caudal CSFP increased (mean, 0.65 mm Hg). The CSFP differential did not change significantly after decompression. Cranial CSFPPA was greater than caudal CSFPPA, but this differential did not change during compression. On decompression, the caudal CSFPPA increased in some but not all animals.

CONCLUSION

Although extradural compression exists at the site of injury, lumbar CSFP may not accurately indicate CSFP cranial to the injury. Decompression may provide immediate, though perhaps partial, resolution of the pressure differential. CSFPPA was not a consistent indicator of decompression in this animal model. These findings may have implications for the design of future clinical protocols in which CSFP is monitored after acute SCI.

Descending thoracic aortic surgery: update on mortality, morbidity, risk assessment and management

PURPOSE OF REVIEW

The purpose of this review is to summarize the literature on thoracic aortic surgery, as well as key management guidelines in the perioperative period. This is particularly timely, as endovascular techniques continue to evolve and become more available.

RECENT FINDINGS

Endovascular treatment of thoracic aortic disease is expanding in applications and case complexity.

SUMMARY

With the expanded use of endovascular techniques to treat aortic disease, midterm and long-term outcome studies and comparisons to open surgical approach are now being published with increasing frequency. This review analyzes the available literature on preventing adverse outcomes after descending thoracic aortic surgery, with specific attention to mortality, morbidity, risk assessment and management in the perioperative setting.

Neurological complications of thoracic endovascular aortic repair

Thoracic endovascular aortic repair (TEVAR) has decreased the morbidity and mortality associated with open surgical repair of descending thoracic aortic diseases, but important complications unique to the procedure remain. Spinal cord ischemia and infarction is a recognized complication caused by endovascular coverage or injury to spinal cord collateral vessels. Stroke is a consequence of thromboembolism or coverage of aortic arch branch vessels with insufficient collateral circulation. Understanding the risk factors and the pathophysiology of neurological complications of TEVAR are important for the successful anesthetic and surgical management and treatment of patients undergoing endovascular procedures involving the thoracic aorta.