Characterization of the spectrum of hemodynamic profiles in trauma patients with acute neurogenic shock

A Review of Strategies Associated with Surgical Decompression in Traumatic Spinal Cord Injury

Traumatic spinal cord injury (TSCI) is frequent. Timely diagnosis and treatment have reduced the mortality, but the long-term recovery of neurologic functions remains ominous. After TSCI, tissue bleeding, edema, and adhesions lead to an increase in the intraspinal pressure, further causing the pathophysiologic processes of ischemia and hypoxia and eventually accelerating the cascade of secondary spinal cord injury. Timely surgery with appropriate decompression strategies can reduce that secondary injury. However, disagreement about the safety and effectiveness of decompression surgery and the timing of surgery still exists. The level and severity of spinal cord injury do have an impact on the timing of surgery; therefore, TSCI subpopulations may benefit from early surgery. Early surgery perhaps has little effect on recovery from complete TSCI but might be of benefit in patients with incomplete injury. Early decompression should be considered in patients with incomplete cervical TSCI. Patient age should not be used as an exclusion criterion for early surgery. The best time point for early surgery is although influenced by the shortest duration to thoroughly examine the patient's condition and stabilize the patient's state. After the patient's condition is fully evaluated, we can perform the surgical modality of emergency myelotomy and decompression. Therefore, a number of conditions should be considered, such as standardized decompression methods, indications and operation timing to ensure the effectiveness and safety of early surgical intervention, and promotion of the functional recovery of residual nerve tissue.

Pilot study: advanced haemodynamic monitoring after acute spinal cord injury-Keep the pressure up?

BACKGROUND

Although the use of vasopressors to maintain haemodynamic goals after acute spinal cord injury (SCI) is still recommended, evidence regarding the target values and possible risks of this practice is limited, and data on haemodynamic parameters unaffected by catecholamines are rare. In this pilot study, we show the haemodynamic profile of patients with acute SCI mainly unaffected by vasopressor use and other factors that influence the cardiovascular system.

METHODS

From March 2018 to March 2020, we conducted a prospective, single-centre pilot study of 30 patients with acute SCI. Factors that could affect the cardiocirculatory system other than SCI (sepsis, pre-existing heart disease or multiple trauma) led to exclusion. A total of 417 measurements were performed using the PiCCO™ system.

RESULTS

The mean systemic vascular resistance index (SVRI, 1447.23 ± 324.71 dyn*s*cm^-5*m²), mean central venous pressure (CVP, 10.69 ± 3.16) and mean global end-diastolic volume index (GEDVI, 801.79 ± 158.95 ml/m²) deviated from the reference range, while the mean cardiac index (CI), mean stroke volume index (SVI), mean arterial pressure (MAP), and mean heart rate (HR) were within the reference range, as indicated in the literature. A mixed model analysis showed a significant negative relationship between norepinephrine treatment and MAP (83.97 vs. 73.69 mmHg, p < 0.001), SVRI (1463.40 vs. 1332.14 dyn*s*cm^-5*m², p = 0.001) and GEDVI (808.89 vs. 759.39 ml/m², p = 0.001).

CONCLUSION

These findings could lead to an adaptation of the target range for SVRI and MAP in patients with acute SCI and therefore reduce the use of vasopressors.

Initial blood pressure is important for long-term outcome after traumatic spinal cord injury

OBJECTIVE

Patients with traumatic spinal cord injury (TSCI) are at risk of developing neurogenic shock that causes hypotension and thereby secondary injury to the spinal cord due to ischemia. Hemodynamic treatment of patients with acute TSCI remains inadequately elucidated. Guidelines for management are divergent and based on limited evidence. To this end, the authors evaluated whether mean arterial blood pressure (MABP) during the prehospital and initial hospital phases of TSCI treatment is correlated with long-term neurological outcome.

METHODS

The authors performed a retrospective cohort study based on a chart review of MABP data collected during the prehospital transport, in the operating room (OR), and in the neurointensive care unit (NICU) during the first 7 days after trauma. Data from the NICU were divided into two periods: days 1-2 and days 3-7. Data were analyzed using Spearman's rank correlation to evaluate for any correlation between MABP and changes in the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) score 1 year postinjury. In the analysis, the MABP target value was 80 mm Hg. Hypotension was treated with metaoxedrin or norepinephrine. Statistically significant differences were evaluated using Spearman's rank correlation coefficient.

RESULTS

The chart review yielded 129 patients treated for TSCI. The inclusion period was 2010-2017. For the prehospital transport measurements of MABP, the Spearman's rank correlation coefficient was a rho of 0.5662 (p < 0.001), for OR measurements it was a rho of 0.6818 (p < 0.001), and for the NICU measurements it was a rho of 0.4611 (p < 0.001); for NICU unit days 1-2 and days 3-7, the Spearman's rank correlation coefficient was a rho of 0.2209 (p = 0.0681).

CONCLUSIONS

Continuous MABP levels exceeding 80 mm Hg have a significant impact on neurological outcome-from earliest possible stabilization in the prehospital care, through hospital admission, the surgical phase, and into the first 2 days in the NICU.

Early decompressive surgery in patients with traumatic spinal cord injury improves neurological outcome

BACKGROUND

The role and timing of a decompressive surgical intervention in patients with traumatic spinal cord injury (SCI) remain controversial. Given the impact of SCI on the individual and society, decompressive surgery to reduce the extent of tissue destruction and improving neurological outcome after initial spinal cord trauma are needed.

OBJECTIVE

To evaluate any possible correlation between the time of a decompressive procedure after traumatic SCI and end-neurologic outcome for traumatic SCI patients.

METHODS

A retrospective cohort study on patients with traumatic SCI in Western Denmark from 2010 to 2017. Data on date and time of injury and time of surgery and data on neurologic status at admission and one-year post-trauma were found in the Electronic Patients Journal (EPJ) and in paper journals. Patients were divided into 4 groups (< 6 h, < 12 h, < 24 h, and > 24 h) based on the time between injury and surgery. Further, patients were separated into two groups depending on whether they did or did not achieve neurological improvement one-year post-trauma. We used Fisher's exact test to compare the abovementioned groups to examine an eventual correlation between time from injury to operation and change in neurological outcome one-year post-trauma.

RESULTS

Patients undergoing surgery < 24 h after trauma obtained a significantly better neurological outcome as compared with patients who underwent surgery > 24 h after trauma (p < 0.001). This result did not change for subgroups of incomplete SCI patients (p = 0.002). However, complete SCI patients operated < 24 h as compared with > 24 h did not obtain better outcome (p = 0.14). We did not find a statistically significant correlation when time from trauma to surgery was reduced further to < 6 or < 12 h post-trauma. Furthermore, stratification on patients undergoing surgery before and after 24 h was made regarding gender, completeness, and years of age. The groups did not differ concerning gender and SCI completeness, but significant difference in age was found (44 and 58 years of age, respectively, p < 0.001). The chance of improved outcome was significantly higher for patients < 50 years of age (42% versus 24%, p = 0.05). Patients under the age of 50 seemed to benefit from early intervention (50% improvement versus 23%); however, difference was not statistically significant (p = 0.08). In patients aged above 50, the trend was similar, but significant correlation was found (40% versus 16%, p = 0.05).

CONCLUSION

The present study reports a beneficial effect of early decompression surgery, especially for incomplete SCI patients; however, surgical decision-making is complex, and all cases of acute spinal cord injury should be cautiously interpreted and handled on an individual basis.

[Red Flags and Shock Symptoms]

Red Flags and Shock Symptoms Abstract. The term 'red flags' is often used in emergency medicine. However, there is no clear medical definition in German for 'red flag'. In most cases, 'red flags' are warning symptoms that indicate a potentially harmful threat to a patient's health. This article wants to explain and define the term 'red flags'. Red flags are explained in emergency medicine and especially in shock in the context of their basic pathophysiological causes. The aim is to improve the understanding of the timely recognition and the exact interpretation of these warning symptoms in the preclinical environment, in order to immediately start a sufficient therapy.

Heller A, Sabashnikov A, Teske W. The Nomenclature, Definition and Distinction of Types of Shock

BACKGROUND

A severe mismatch between the supply and demand of oxygen is the common feature of all types of shock. We present a newly developed, clinically oriented classification of the various types of shock and their therapeutic implications.

METHODS

This review is based on pertinent publications (1990-2018) retrieved by a selective search in PubMed, and on the relevant guidelines and meta-analyses.

RESULTS

There are only four major categories of shock, each of which is mainly related to one of four organ systems. Hypovolemic shock relates to the blood and fluids compartment while distributive shock relates to the vascular system; cardiogenic shock arises from primary cardiac dysfunction; and obstructive shock arises from a blockage of the circulation. Hypovolemic shock is due to intravascular volume loss and is treated by fluid replacement with balanced crystalloids. Distributive shock, on the other hand, is a state of relative hypovolemia resulting from pathological redistribution of the absolute intravascular volume and is treated with a combination of vasoconstrictors and fluid replacement. Cardiogenic shock is due to inadequate function of the heart, which shall be treated, depending on the situation, with drugs, surgery, or other interventional procedures. In obstructive shock, hypoperfusion due to elevated resistance shall be treated with an immediate life-saving intervention.

CONCLUSION

The new classification is intended to facilitate the goal-driven treatment of shock in both the pre-hospital and the inpatient setting. A uniform treatment strategy should be established for each of the four types of shock.

Incidence and Natural Progression of Neurogenic Shock after Traumatic Spinal Cord Injury

Neurogenic shock, a distributive type of circulatory shock after spinal cord injury (SCI), results in profound hypotension. The consequent hemodynamic instability complicates clinical management, delays surgical intervention, and impacts neurological outcome. Moreover, the reported incidence of this condition varies significantly. We establish the true incidence of neurogenic shock by comparing the most common clinical definitions used to diagnose the condition. Further, we characterize the acute progression and recovery of neurogenic shock. Daily blood pressure, heart rate, and fluid management as well as vasopressor therapy and neurologic status were collected over 30 days from 84 adults admitted to our tertiary trauma center after cervical (n = 56) and thoracic (n = 28) SCI. We found that the reported incidence of neurogenic shock varied greatly depending on which clinical definition was applied. By using a novel combination of hemodynamic and laboratory criteria to define neurogenic shock, the calculated incidence (29% cervical SCI) in our sample most appropriately reflects the true incidence, finding that hypovolemia was the primary factor responsible for the inconsistency in incidence reports between studies. In addition, we found a characteristic decline in blood pressure after the first week post-injury and that fluid management is not currently an integral aspect of clinical management (all persons were treated at a net fluid intake ≤ zero). The results demonstrate the need for accurate identification of neurogenic shock through consistent and appropriate criteria, which is not only important from a clinical point of view, but also in establishing accurate epidemiology to responsibly allocate resources to its management.

[Anesthesiological approach for patients with spinal cord injuries]

Spinal cord injuries (SCI) are serious medical conditions, which are associated with severe and potentially fatal risks and complications depending on the location and extent of injury. Traffic accidents, falls and recreational activities are the leading causes for traumatic SCI (TSCI) worldwide whereas non-traumatic spinal cord injuries (NTSCI) are mostly due to tumors and congenital diseases. As chronification of the injuries progresses other organ systems are affected including anatomical changes, the respiratory and cardiovascular systems and endocrinological pathways. All these effects have to be considered in the anesthesiological management of patients with SCI. Autonomic dysreflexia (AD) is the most dangerous and life-threatening complication in patients with chronic SCI above T6 that results from an overstimulation of sympathetic reflex circuits in the upper thoracic spine and can be fatal. This article summarizes the specific pathophysiology of SCI and how AD can be avoided as well as also providing anesthetists with strategies for perioperative and intensive care management of patients with SCI.

Spinal cord injury enhances arterial expression and reactivity of α1-adrenergic receptors-mechanistic investigation into autonomic dysreflexia

BACKGROUND CONTEXT

Autonomic dysreflexia (AD) usually presents with a significant increase in blood pressure, and uncontrollable autonomic response to stimuli below the level of spinal cord injury (SCI).

PURPOSE

This study analyzed the vasomotor function and molecular changes in the peripheral arteries below the lesion of SCI to characterize the mechanism of autonomic dysreflexia.

STUDY DESIGN

This was a randomized experimental study in rats.

METHODS

Contusive SCI was induced using a force-calibrated weight-drop device at the T10 level in anesthetized rats. Two weeks after severe SCI, blood flow in the femoral arteries was measured, and the vasomotor function and expression of α1-adrenergic receptors were analyzed.

RESULTS

Blood flow in the femoral artery was significantly reduced in rats with SCI (8.0±2 vs. 17.5±4 mL/min, SCI vs. control, respectively; p=.016). The contraction responses of femoral artery segments to cumulative addition of α1-adrenergic agonist phenylephrine were significantly enhanced in rats with SCI. Expression of α1-adrenergic receptor was upregulated in the medial layer of femoral artery vascular homogenates of these rats.

CONCLUSION

Our study provides evidence demonstrating that prolonged denervation below the lesion level following SCI results in a compensatory increased expression of α1-adrenergic receptors in the arterial smooth muscle layer, thereby enhancing the responsiveness to α1-adrenergic agonist and potentiating the development of AD.

Complications and outcomes of vasopressor usage in acute traumatic central cord syndrome

OBJECT

The optimal mean arterial pressure (MAP) for spinal cord perfusion after trauma remains unclear. Although there are published data on MAP goals after spinal cord injury (SCI), the specific blood pressure management for acute traumatic central cord syndrome (ATCCS) and the implications of these interventions have yet to be elucidated. Additionally, the complications of specific vasopressors have not been fully explored in this injury condition.

METHODS

The present study is a retrospective cohort analysis of 34 patients with ATCCS who received any vasopressor to maintain blood pressure above predetermined MAP goals at a single Level 1 trauma center. The collected variables were American Spinal Injury Association (ASIA) grades at admission and discharge, administered vasopressor and associated complications, other interventions and complications, and timing of surgery. The relationship between the 2 most common vasopressors—dopamine and phenylephrine—and complications within the cohort as a whole were explored, and again after stratification by age.

RESULTS

The mean age of the ATCCS patients was 62 years. Dopamine was the most commonly used primary vasopressor (91% of patients), followed by phenylephrine (65%). Vasopressors were administered to maintain MAP goals fora mean of 101 hours. Neurological status improved by a median of 1 ASIA grade in all patients, regardless of the choice of vasopressor. Sixty-four percent of surgical patients underwent decompression within 24 hours. There was no observed relationship between the timing of surgical intervention and the complication rate. Cardiogenic complications associated with vasopressor usage were notable in 68% of patients who received dopamine and 46% of patients who received phenylephrine. These differences were not statistically significant (OR with dopamine 2.50 [95% CI 0.82–7.78], p = 0.105). However, in the subgroup of patients > 55 years, dopamine produced statistically significant increases in the complication rates when compared with phenylephrine (83% vs 50% for dopamine and phenylephrine, respectively; OR with dopamine 5.0 [95% CI 0.99–25.34], p = 0.044).

CONCLUSIONS

Vasopressor usage in ATCCS patients is associated with complication rates that are similar to the reported literature for SCI. Dopamine was associated with a higher risk of complications in patients > 55 years. Given the increased incidence of ATCCS in older populations, determination of MAP goals and vasopressor administration should be carefully considered in these patients. While a randomized control trial on this topic may not be practical, a multiinstitutional prospective study for SCI that includes ATCCS patients as a subpopulation would be useful for examining MAP goals in this population.

Theoretical Analysis of the Relative Impact of Obesity on Hemodynamic Stability During Acute Hemorrhagic Shock

Background:

Evidence suggests that morbid obesity may be an independent risk factor for adverse outcomes in patients with traumatic injuries.

Objectives:

In this study, a theoretic analysis using a derivation of the Guyton model of cardiovascular physiology examines the expected impact of obesity on hemodynamic changes in Mean Arterial Pressure (MAP) and Cardiac Output (CO) during Hemorrhagic Shock (HS).

Patients and Methods:

Computer simulation studies were used to predict the relative impact of increasing Body Mass Index (BMI) on global hemodynamic parameters during HS. The analytic procedure involved recreating physiologic conditions associated with changing BMI for a virtual subject in an In Silico environment. The model was validated for the known effect of a BMI of 30 on iliofemoral venous pressures. Then, the relative effect of changing BMI on the outcome of target cardiovascular parameters was examined during simulated acute loss of blood volume in class II hemorrhage. The percent changes in these parameters were compared between the virtual nonobese and obese subjects. Model parameter values are derived from known population distributions, producing simulation outputs that can be used in a deductive systems analysis assessment rather than traditional frequentist statistical methodologies.

Results:

In hemorrhage simulation, moderate increases in BMI were found to produce greater decreases in MAP and CO compared to the normal subject. During HS, the virtual obese subject had 42% and 44% greater falls in CO and MAP, respectively, compared to the nonobese subject. Systems analysis of the model revealed that an increase in resistance to venous return due to changes in intra-abdominal pressure resulting from obesity was the critical mechanism responsible for the differences.

Conclusions:

This study suggests that obese patients in HS may have a higher risk of hemodynamic instability compared to their nonobese counterparts primarily due to obesity-induced increases in intra-abdominal pressure resulting in reduced venous return.