Current practices and goals for mean arterial pressure and spinal cord perfusion pressure in acute traumatic spinal cord injury: Defining the gaps in knowledge

Postoperative Spinal Cord Ischemia Monitoring: A Review of Techniques Available after Endovascular Aortic Repair

BACKGROUND

Spinal cord ischemia is one of the complications that can occur after open and endovascular thoracoabdominal aortic repair. This occurs despite various perioperative approaches, including distal aortic perfusion, hybrid procedures with extra anatomical bypasses, motor-evoked potential, and cerebrospinal fluid drainage. The inability to recognize spinal ischemia in a timely manner remains a devastating complication after thoracoabdominal aortic repair.This review aims to look at novel technologies that are designed for continuous monitoring to detect early changes that signal the development of spinal cord ischemia and to discuss their benefits and limitations.

METHODS

We conducted a systematic review of the technologies available for continuous monitoring in the intensive care unit for early detection of spinal cord ischemia. Studies were eligible for inclusion if they used different technologies for monitoring spinal ischemia during the postoperative period. All articles that were not available in English were excluded. To ensure that all relevant articles were included, no other significant restrictions were imposed.

RESULTS

We identified 59 studies from the outset to December 2022 to be included in our study. New techniques have been studied as potentially useful monitoring tools that could provide simple and effective monitoring of the spinal cord. These include near-infrared spectroscopy, contrast-enhanced ultrasound, magnetic resonance imaging, fiber optic monitoring of the spinal cord, and cerebrospinal fluid biomarkers.

CONCLUSIONS

Despite the development of new techniques to monitor for postoperative spinal cord ischemia, their use remains limited. We recommend more future research to ensure rapid intervention for our patients.

A Guide to the Use of Vasopressors and Inotropes for Patients in Shock

Shock is a life-threatening circulatory failure that results in inadequate tissue perfusion and oxygenation. Vasopressors and inotropes are vasoactive medications that are vital in increasing systemic vascular resistance and cardiac contractility, respectively, in patients presenting with shock. To be well versed in using these agents is an important skill to have in the critical care setting where patients can frequently exhibit symptoms of shock. In this review, we will discuss the pathophysiological mechanisms of shock and evaluate the current evidence behind the management of shock with an emphasis on vasopressors and inotropes.

Spinal subdural haemorrhage secondary to strenuous exercise and warfarin, complicated by acute ischaemic stroke

Spinal subdural haemorrhage or haematoma (SSDH) is a rare condition that is often overlooked and missed on initial presentation due to its non-specific features that may mimic other more common pathologies. It is associated with high morbidity and mortality rates, with few evidence-based management principles, particularly during the subacute stages of recovery. In this report, we detail a case of SSDH associated with exercise and anticoagulation therapy, which was complicated by acute ischaemic stroke. SSDH should be suspected in cases of acute back pain without a clear alternative cause, particularly in coagulopathic individuals. Following treatment, early recommencement of anticoagulation therapy may be justified in certain cases where indicated, after careful consideration of the affected individual's risk profile.

[Anesthesia in spinal surgery]

Over the past 20 years improvements in surgical techniques and perioperative patient care have led to a considerable increase in surgical procedures of the spine worldwide. Therefore, the spectrum was extended from minimally invasive procedures up to complex operations over several segments of the spinal column with high loss of blood and complex perioperative management. This article presents the principal pillars of preoperative, intraoperative and postoperative management relating to spinal surgery. Furthermore, procedure-specific features, such as airway management in cervical spine instability or implementation of intraoperative neuromonitoring are dealt with in detail.

Cerebrospinal Fluid Drainage for Prevention of Spinal Cord Ischemia in Thoracic Endovascular Aortic Surgery-Pros and Cons

Thoracic endovascular aortic repair (TEVAR) carries a risk of spinal cord ischemia (SCI) which exerts a devastating impact on patient's quality of life and life expectancy. Although routine prophylactic cerebrospinal fluid (CSF) drainage is not unequivocally supported by current data, several studies have demonstrated favorable outcomes. Patients at high risk for SCI following TEVAR likely will benefit from prophylactic CSF drains. However, the intervention is not risk free, and thorough risk/benefit analysis should be individualized to each patient.

Laryngoscopy mediated stress response induces opposite effects on cerebral and paraspinal oxygen saturation

Background: Intraoperative sympathetic stimulation induces a cascade of metabolic and hormonal changes. It increases perfusion of vital organs, but also causes vasoconstriction of blood vessels supplying less vital organs, potentially leading to organ injury. To date, it is unknown how an endogenous stress reaction affects the spinal cord blood supply. Near-infrared spectroscopy (NIRS) can be applied paravertebrally to monitor the oxygenation of the collateral network, which contributes to the spinal cord blood supply. It has already been demonstrated that regional cerebral oxygen saturation (rScO2) increases following sympathetic stimulation. Objectives: We hypothesized that laryngoscopy would cause an increase in cerebral and paraspinal regional tissue saturations (rScO2 and rSpsO2, respectively). Design: Retrospective analysis of a previous conducted randomized trial. Setting: Laryngoscopy in the operating room. Methods: Data of 28 patients, scheduled for arterial dilation of the lower limb, were retrospectively analyzed. Before induction of anesthesia, standard monitoring, BIS and 8 NIRS sensors were applied (two on the forehead, six bilaterally on the back at T3-T4, T9-T10 and L1-L2). Sympathetic stimulation was induced by laryngoscopy. Main outcome measures: Changes in rStO2 following sympathetic stimulation induced by laryngoscopy. Results: Following laryngoscopy, rScO2 significantly increased and rSpsO2 significantly decreased at T9-T10 and L1-L2. The relative changes (regional tissue oxygen saturation (rStO2) after intubation-rStO2 before intubation)/ rStO2 before intubation), at cerebral level, T9-T10 and L1-L2 were 9%, -5% and -3%, respectively (p < 0.01). rSpsO2 at T3-T4 did not change significantly. Changes (Δ) in mean arterial pressure following laryngoscopy were weakly correlated with ΔrScO2 and moderately correlated with ΔrSpsO2 at T9-T10 and L1-L2. Conclusions: Intraoperative sympathetic stimulation may decrease the oxygen supply to the spinal cord. Trial registration: The trial was registered at ClinicalTrials.gov (NCT 03767296).

Significance of spinal cord perfusion pressure following spinal cord injury: A systematic scoping review

This scoping review systematically reviewed relevant research to summarize the literature addressing the significance of monitoring spinal cord perfusion pressure (SCPP) in acute traumatic spinal cord injury (SCI). The objectives of the review were to (1) examine the nature of research in the field of SCPP monitoring in SCI, (2) summarize the key research findings in the field, and (3) identify research gaps in the existing literature and future research priorities. Primary literature searches were conducted using databases (Medline and Embase) and expanded searches were conducted by reviewing the references of eligible articles and searches of Scopus, Web of Science core collection, Google Scholar, and conference abstracts. Relevant data were extracted from the studies and synthesis of findings was guided by the identification of patterns across studies to identify key themes and research gaps within the literature. Following primary and expanded searches, a total of 883 articles were screened. Seventy-three articles met the review inclusion criteria, including 34 original research articles. Other articles were categorized as conference abstracts, literature reviews, systematic reviews, letters to the editor, perspective articles, and editorials. Key themes relevant to the research question that emerged from the review included the relationship between SCPP and neurological recovery, the safety of monitoring pressures within the intrathecal space, and methods of intervention to enhance SCPP in the setting of acute traumatic SCI. Original research that aims to enhance SCPP by targeting increases in mean arterial pressure or reducing pressure in the intrathecal space is reviewed. Further discussion regarding where pressure within the intrathecal space should be measured is provided. Finally, we highlight research gaps in the literature such as determining the feasibility of invasive monitoring at smaller centers, the need for a better understanding of cerebrospinal fluid physiology following SCI, and novel pharmacological interventions to enhance SCPP in the setting of acute traumatic SCI. Ultimately, despite a growing body of literature on the significance of SCPP monitoring following SCI, there are still a number of important knowledge gaps that will require further investigation.

The Next Frontier in Neurocritical Care in Resource-Constrained Settings

Neurocritical care (NCC) is an emerging field within critical care medicine, reflecting the widespread prevalence of neurologic injury in critically ill patients. Morbidity and mortality from neurocritical illness (NCI) have been reduced substantially in resource-rich settings (RRS), owing to the development of advanced technologies, neuro-specific units, and subspecialized medical training. Despite shouldering much of the burden of NCI worldwide, resource-limited settings (RLS) face immense hurdles when implementing guidelines generated in RRS. This review summarizes the current epidemiology, management, and outcomes of the most common NCIs in RLS and offers commentary on future directions in NCC practiced in RLS.

Decision tree–based machine learning analysis of intraoperative vasopressor use to optimize neurological improvement in acute spinal cord injury

OBJECTIVE

Previous work has shown that maintaining mean arterial pressures (MAPs) between 76 and 104 mm Hg intraoperatively is associated with improved neurological function at discharge in patients with acute spinal cord injury (SCI). However, whether temporary fluctuations in MAPs outside of this range can be tolerated without impairment of recovery is unknown. This retrospective study builds on previous work by implementing machine learning to derive clinically actionable thresholds for intraoperative MAP management guided by neurological outcomes.

METHODS

Seventy-four surgically treated patients were retrospectively analyzed as part of a longitudinal study assessing outcomes following SCI. Each patient underwent intraoperative hemodynamic monitoring with recordings at 5-minute intervals for a cumulative 28,594 minutes, resulting in 5718 unique data points for each parameter. The type of vasopressor used, dose, drug-related complications, average intraoperative MAP, and time spent in an extreme MAP range (< 76 mm Hg or > 104 mm Hg) were collected. Outcomes were evaluated by measuring the change in American Spinal Injury Association Impairment Scale (AIS) grade over the course of acute hospitalization. Features most predictive of an improvement in AIS grade were determined statistically by generating random forests with 10,000 iterations. Recursive partitioning was used to establish clinically intuitive thresholds for the top features.

RESULTS

At discharge, a significant improvement in AIS grade was noted by an average of 0.71 levels (p = 0.002). The hemodynamic parameters most important in predicting improvement were the amount of time intraoperative MAPs were in extreme ranges and the average intraoperative MAP. Patients with average intraoperative MAPs between 80 and 96 mm Hg throughout surgery had improved AIS grades at discharge. All patients with average intraoperative MAP > 96.3 mm Hg had no improvement. A threshold of 93 minutes spent in an extreme MAP range was identified after which the chance of neurological improvement significantly declined. Finally, the use of dopamine as compared to norepinephrine was associated with higher rates of significant cardiovascular complications (50% vs 25%, p < 0.001).

CONCLUSIONS

An average intraoperative MAP value between 80 and 96 mm Hg was associated with improved outcome, corroborating previous results and supporting the clinical verifiability of the model. Additionally, an accumulated time of 93 minutes or longer outside of the MAP range of 76–104 mm Hg is associated with worse neurological function at discharge among patients undergoing emergency surgical intervention for acute SCI.

Perioperative management in complex spine surgery: a narrative review

The last two decades have seen a significant increase in the number of spine surgical procedures performed worldwide. This type of surgery includes a wide variety of procedures, from mini-invasive discectomies to multi-level spinal arthrodesis and osteotomies. Moreover, different surgical approaches are described at different spine levels: the anesthesiologist should be aware of the potential benefits and risks for the patients and be prepared for their management. In this narrative review we seek to describe basic concepts of perioperative spine care and address evolving areas in which care is changing. We will discuss preoperative concerns, intraoperative management including airway management, choice of maintenance, intraoperative neuromonitoring and anesthetic effect, blood management and the dynamic topic of anesthetic and analgesic techniques. Finally, we will briefly address the issue of perioperative complications as they relate specifically to spine surgery.

Trauma Indicators in Spinal Cord Injury Rehabilitation Outcomes: A Retrospective Cohort Analysis of the National Trauma Data Bank and National Spinal Cord Injury Database

OBJECTIVE

To investigate whether initial emergency room physiologic measures and metrics of trauma severity predict functional outcomes and neurologic recovery in traumatic spinal cord injury.

DESIGN

Retrospective analysis of a clinical database.

SETTING

Merged multi-center data from the Spinal Cord Injury Model Systems (SCIMS) database and National Trauma Data Bank (NTDB) from six academic medical centers across the United States.

PARTICIPANTS

319 patients admitted to SCIMS rehabilitation centers within one-year of injury. The majority of patients were male (76.2%), with a mean age of 44 (SD 19). At rehabilitation admission, the most common neurologic level of injury was low cervical (C5-C8, 39.5%) and ASIA impairment scale (AIS) was A (34.4%).

MAIN OUTCOME MEASURES(S)

Primary outcomes were (1) Functional Independence Measure (FIM) motor score at discharge from inpatient rehabilitation and (2) change in FIM motor score between inpatient rehabilitation admission and discharge. We hypothesized that derangements in emergency room physiologic measures, such as decreased blood pressure and oxygen saturation, as well as increased severity of trauma burden, would predict poorer functional outcomes.

RESULTS

Linear regression analysis showed that neurologic level of injury and AIS predicted discharge FIM motor score. Systolic blood pressure, heart rate, oxygen saturation, need for assisted respiration, and presence of penetrating injury did not predict discharge motor FIM or FIM motor score improvement.

CONCLUSIONS

Initial emergency room physiologic parameters did not prognosticate functional outcomes in this cohort.

Should asymptomatic cervical stenosis be treated in the setting of progressive thoracic myelopathy? A systematic review of the literature

PURPOSE

Unlike tandem stenosis of the cervical and lumbar spine, tandem cervical and thoracic stenosis (TCTS) of the spine is less common, and the approach and order of intervention are controversial. We aim to review the literature to evaluate the incidence and interventions for patients with cervical and thoracic stenosis. We provide illustrative cases to demonstrate that thoracic myelopathy in the setting of asymptomatic cervical stenosis can be treated safely.

METHODS

A systematic review of the literature through electronic databases of PubMed, EMBASE, Web of Science, and Cochrane Library was performed to present the current literature that evaluates TCTS as it relates to incidence and surgical interventions. We also present two cases of patients undergoing operative intervention for thoracic myelopathy in the setting of concurrent cervical stenosis.

RESULTS

A total of 26 English original studies and case reports were identified. Nine studies evaluated the incidence of TCTS. 20 studies with a total of 168 patients with TCTS presented information on surgical intervention options. There is an overall aggregate incidence of 11.6% (530/4751) based on incidence studies. 165 patients underwent thoracic intervention. Of these patients, 63 patients underwent cervical intervention first, 29 underwent thoracic intervention first, and 73 underwent simultaneous, single-stage intervention.

CONCLUSIONS

In patients presenting with myelopathy, both cervical and thoracic spine should be evaluated for TCTS. Order of operative intervention is tailored to clinical and radiographic information. In cases of thoracic myelopathy with asymptomatic cervical stenosis, thoracic intervention can be pursued with precautions to prevent further cervical cord injury.

Safety and Feasibility of Lumbar Cerebrospinal Fluid Pressure and Intraspinal Pressure Studies in Cervical Stenosis: A Case Series

INTRODUCTION

Degenerative cervical myelopathy (DCM) leads to functional impairment by compression of the spinal cord and nerve roots. In DCM, the dynamics of cerebrospinal fluid pressure (CSFP) and intraspinal pressure (ISP), as well as spinal cord perfusion pressure (SCPP) remain not investigated yet. Recent technical advances have enabled investigation of these parameters in acute spinal cord injury (SCI). We aim to investigate the properties of CSFP/ISP and spinal cord hemodynamics during and after decompressive surgery in DCM.

MATERIALS AND METHODS

Four patients with DCM were enrolled; during surgery and 24 h postoperative, ISP at level was measured in one patient, and CSFP was measured in two patients. In one patient, CSFP was recorded at bedside before surgery.

RESULTS

All measurements were conducted without adverse events and were well tolerated. With CSFP analysis, post-decompression Queckenstedt's test was responsive in two patients (i.e., jugular vein compression resulted in an elevation of CSFP pressure). In the patient whose CSFP was tested at bedside, Queckenstedt's test was not responsive before decompression. Individual optimum SCPPs were calculated to be between 70 and 75 mmHg.

CONCLUSION

ISP and CSFP can reflect spinal compression and sufficient decompression. A better understanding and systematic monitoring possibly lead to improved hemodynamic management and may allow early recognition of postoperative complications such as swelling and bleeding.

Early Trauma Indicators and Rehabilitation Outcomes in Traumatic Spinal Cord Injury

Objectives

To investigate the relationship between early trauma indicators and neurologic recovery after traumatic SCI using standardized outcome measures from the ISNCSCI examination and standardized functional outcome measures for rehabilitation populations.

Methods

This is a retrospective review of merged, prospectively collected, multicenter data from the Spinal Cord Injury Model Systems (SCIMS) database and institutional trauma databases from five academic medical centers across the United States. Functional status at inpatient rehabilitation discharge and change in severity and level of injury from initial SCI to inpatient rehabilitation discharge were analyzed to assess neurologic recovery for patients with traumatic SCI. Linear and logistic regression with multiple imputation were used for the analyses.

Results

A total of 209 patients were identified. Mean age at injury was 47.2 ± 18.9 years, 72.4% were male, 22.4% of patients had complete injuries at presentation to the emergency department (ED), and most patients were admitted with cervical SCI. Mean systolic blood pressure (SBP) was 124.1 ± 29.6 mm Hg, mean ED heart rate was 83.7 ± 19.9 bpm, mean O2 saturation was 96.8% ± 4.0%, and mean Glasgow Coma Scale (GCS) score was 13.3 ± 3.9. The average Injury Severity Score (ISS) in this population was 22.4. Linear regression analyses showed that rehabilitation discharge motor FIM was predicted by motor FIM on admission and ISS. Requiring ventilatory support on ED presentation was negatively associated with improvement of ASIA Impairment Scale (AIS) grade at rehabilitation discharge compared with AIS grade after initial injury. Emergency room physiologic measures (SBP, pulse, oxygen saturation) did not predict discharge motor FIM or improvement in AIS grade or neurological level of injury.

Conclusion

Our study showed a positive association between discharge FIM and ISS and a negative association between ventilatory support at ED presentation and AIS improvement. The absence of any significant association between other physiologic or clinical variables at ED presentation with rehabilitation outcomes suggests important areas for future clinical research.

Extended durotomy to treat severe spinal cord injury after acute thoracolumbar disc herniation in dogs

OBJECTIVE

To report recovery of ambulation of dogs treated with extended thoracolumbar durotomy for severe spinal cord injury caused by intervertebral disc herniation.

STUDY DESIGN

Descriptive cohort.

ANIMALS

Twenty-six consecutive paraplegic dogs presented with loss of deep pain sensation after acute thoracolumbar intervertebral disc herniation.

METHODS

Each dog underwent routine diagnostic assessment and surgery for removal of extradural herniated intervertebral disc, followed by a four-vertebral body length durotomy centered on the herniated disc. Each dog was followed up until it was able to walk 10 steps without assistance or until 6 months after surgery.

RESULTS

Sixteen of 26 dogs recovered to walk unaided (all but one also recovered fecal and urinary continence), and six dogs did not; four dogs were lost to follow-up. One dog was euthanized because of signs consistent with progressive myelomalacia. There was no evidence of detrimental effects of durotomy within the period of study. Using Bayesian analysis, we found a point estimate of successful outcome of 71% with 95% credible interval from 52% to 87%.

CONCLUSION

Extended durotomy seemed to improve the outcome of dogs in our case series without increase in morbidity.

CLINICAL SIGNIFICANCE

Extended durotomy appears safe and may improve the outcome of dogs with severe thoracolumbar mixed contusion and compressive injuries associated with acute intervertebral disc extrusion.