Does splanchnic ischemia occur in isolated neurotrauma? A prospective observational study

The proteomic and metabolomic signatures of isolated and polytrauma traumatic brain injury

BACKGROUND

The interactions of polytrauma, shock, and traumatic brain injury (TBI) on thromboinflammatory responses remain unclear and warrant investigation as we strive towards personalized medicine in trauma. We hypothesized that comprehensive omics characterization of plasma would identify unique metabolic and thromboinflammatory pathways following TBI.

METHODS

Patients were categorized as TBI vs Non-TBI, and stratified into Polytrauma or minimally injured. Discovery 'omics was employed to quantify the top differently expressed proteins and metabolites of TBI and Non-TBI patient groups.

RESULTS

TBI compared to Non-TBI showed gene enrichment in coagulation/complement cascades and neuronal markers. TBI was associated with elevation in glycolytic metabolites and conjugated bile acids. Division into isolated TBI vs polytrauma showed further distinction of proteomic and metabolomic signatures.

CONCLUSION

Identified mediators involving in neural inflammation, blood brain barrier disruption, and bile acid building leading to TBI associated coagulopathy offer suggestions for follow up mechanistic studies to target personalized interventions.

Nutritional and Bioenergetic Considerations in Critically Ill Patients with Acute Neurological Injury

The brain, due to intensive cellular processes and maintenance of electrochemical gradients, is heavily dependent on a constant supply of energy. Brain injury, and critical illness in general, induces a state of increased metabolism and catabolism, which has been proven to lead to poor outcomes. Of all the biochemical interventions undertaken in the ICU, providing nutritional support is perhaps one of the most undervalued, but potentially among the safest, and most effective interventions. Adequate provisions of calories and protein have been shown to improve patient outcomes, and guidelines for the nutritional support of the critically ill patient are reviewed. However, there are no such specific guidelines for the critically ill patient with neurological injury. Patients with primary or secondary neurological disorders are frequently undernourished, while data suggest this population would benefit from early and adequate nutritional support, although comprehensive clinical evidence is lacking. We review the joint recommendations from the Society for Critical Care Medicine and the American Society for Parenteral and Enteral Nutrition, as they pertain to neurocritical care, and assess the recommendations for addressing nutrition in this patient population.

Superimposed traumatic brain injury modulates vasomotor responses in third-order vessels after hemorrhagic shock

BACKGROUND

Traumatic brain injury (TBI) and hemorrhagic shock (HS) are the leading causes of death in trauma. Recent studies suggest that TBI may influence physiological responses to acute blood loss. This study was designed to assess to what extent superimposed TBI may modulate physiologic vasomotor responses in third-order blood vessels in the context of HS.

METHODS

We have combined two established experimental models of pressure-controlled hemorrhagic shock (HS; MAP 50 mmHg/60 min) and TBI (lateral fluid percussion (LFP)) to assess vasomotor responses and microcirculatory changes in third-order vessels by intravital microscopy in a spinotrapezius muscle preparation. 23 male Sprague-Dawley rats (260-320 g) were randomly assigned to experimental groups: i) Sham, ii) HS, iii) TBI + HS, subjected to impact or sham operation, and assessed.

RESULTS

HS led to a significant decrease in arteriolar diameters by 20% to baseline (p < 0.01). In TBI + HS this vasoconstriction was less pronounced (5%, non-significant). At completed and at 60 minutes of resuscitation arteriolar diameters had recovered to pre-injury baseline values. Assessment of venular diameters revealed similar results. Arteriolar and venular RBC velocity and blood flow decreased sharply to < 20% of baseline in HS and TBI + HS (p < 0.01). Immediately after and at 60 minutes of resuscitation, an overshoot in arterial RBC velocity (140% of baseline) and blood flow (134.2%) was observed in TBI + HS.

CONCLUSION

Superimposed TBI modulated arteriolar and venular responses to HS in third-order vessels in a spinotrapezius muscle preparation. Further research is necessary to precisely define the role of TBI on the microcirculation in tissues vulnerable to HS.

Anaesthesia for acute intestinal obstruction associated with cerebral arteriovenous malformation in a child

This case report describes the perioperative management of a child presenting with acute intestinal obstruction secondary to bowel malrotation after a recent intracranial haemorrhage associated with an intracranial arteriovenous malformation. We discuss the anaesthesia planning for this case, where the 'optimal' management strategies for the two conditions present are potentially conflicting. Issues include rapid sequence induction in the presence of a ruptured arteriovenous malformation, maintenance of cerebral perfusion pressure in the face of bowel ischaemia, and the use of epidural anaesthesia in a child with recent intracranial haemorrhage. Written consent was obtained from the patient and parents to publish this case.

Splanchnic ischemia and gut permeability after acute brain injury secondary to intracranial hemorrhage

INTRODUCTION

Splanchnic ischemia (SI) and increased gut permeability (GP) have been described in acute brain injury (ABI), although their incidence and relation to the type and severity of injury are uncertain. The aim of this study was to evaluate the incidence of both abnormalities in a series of patients with severe ABI secondary to intracranial hemorrhage (ICH) managed with a resuscitation protocol pursuing adequate cerebral and systemic hemodynamics.

METHODS

Eight patients with severe ABI secondary to ICH were admitted to the ICU and were mechanically ventilated and monitored with intracranial pressure measurement, jugular bulb venous oxygen saturation, arterial lactate concentration and gastric tonometry. All patients were managed actively to maintain adequate blood and cerebral perfusion pressures with a protocol based on aggressive fluid resuscitation prior to vasoactive drugs administration. GP was assessed using the lactulose/mannitol test (LMT). Values were recorded during the first 7 days of hospital stay.

RESULTS

Arterial lactate concentration was within the normal range (1.9 +/- 0.5 mmol/l) in all patients. Upon admission, the mean pCO(2) gap was 8.2 +/- 4.3 mmHg (1.09 +/- 0.57 kPa) with an intramucosal pH of 7.4 +/- 0.1. All patients had an abnormal LMT (0.066 +/- 0.055) compared with 19 healthy volunteers (0.025 +/- 0.004) (p < 0.05, Mann Whitney test).

CONCLUSION

Splanchnic ischemia is uncommon among patients with acute brain injury secondary to intracranial hemorrhage, provided they are adequately resuscitated with a protocol based mainly on fluids to achieve an adequate CPP. Gut hyperpermeability is commonly present, despite the absence of splanchnic ischemia.

Endothelin-1, Inducible Nitric Oxide Synthase and Macrophage Inflammatory Protein-1?? in the Pathogenesis of Stress Ulcer in Neurotraumatic Patients

BACKGROUND

To prospectively identify histologically and endoscopically the effect of omeprazole on the expression of endothelin-1 (ET-1), inducible nitric oxide synthase (iNOS) and macrophage inflammatory protein-1alpha (MIP-1alpha) in the gastric mucosa of neurosurgical patients with stress ulcer.

METHODS

Twenty-five patients with severe acute intracranial lesions caused by trauma were enrolled in this study. A 40 mg intravenous bolus of omeprazole (OME) was given daily for 7 days. The intragastric pH was continuously recorded for 24 hours on day 1 and 8. Endoscopic evaluation of the gastric corpus, antrum, and duodenal bulb was performed in the ICU, within 24 hours after brain injury, and at follow-up on the 7th day after admission. Paired biopsies were obtained for histologic examinations and immunohistochemical analysis was performed using a LSAB method for MIP-1alpha, ET-1, and iNOS.

RESULTS

There were 72% and 70% of gastroduodenal mucosal lesions at the initial and follow-up endoscopies, respectively. However, the severity of mucosal lesions showed significant improvement in most patients at follow-up (p < 0.05). Mean percentages of time intragastric pH were greater than or equal to 4.0 were 20 +/- 11% and 70 +/- 17% on day 1 and 8, respectively (p < 0.05). The incidences of ET-1, iNOS and MIP-1alpha expression were not significantly different between the patients before and after OME prophylaxis.

CONCLUSIONS

Prophylactic OME is effective in reducing the severity of stress ulcerations in severe neurotraumatic patients. High incidence of tissue ET-1 expression combined with increased activity of iNOS and MIP-1alpha may be responsible for the gastric mucosal injury. We also show that OME fails to counter the enhancement in the mucosal expression of ET-1, iNOS, and MIP-1alpha caused by severe brain damage.

The 'propofol infusion syndrome': the facts, their interpretation and implications for patient care

AstraZeneca (the manufacturer of Diprivan) presents its review of the history of the so-called 'propofol infusion syndrome', highlighting the difficulties in analysing the incomplete information available. Theories as to its causality are presented and discussed; these include mitochondrial toxicity, mitochondrial defects, impaired tissue oxygenation and carbohydrate deficiency. A review of published and confidential safety data is presented and discussed; it concludes that the major risk factors for its development appear to be poor oxygen delivery, sepsis, serious cerebral injury and high propofol dosage. In some reports an increasing lipaemia was noted and was likely to be due to a failure of hepatic lipid regulation, possibly related to poor oxygenation and/or possibly a lack of glucose. In some cases an increasing lipaemia was the first indication of impending 'propofol infusion syndrome' onset and it should not be viewed as a benign sign. The lipaemia can lead to sequestration of propofol into the lipid phase, leading to lowered free propofol levels and apparent insensitivity to propofol. In conclusion AstraZeneca advocates good haemodynamic and oxygen delivery management, adequate glucose provision, adherence to recommended propofol dosing regimes together with active management of lipaemias to both prevent and treat 'propofol infusion syndrome'.

Organ dysfunction assessment score for severe head injury patients during brain hypothermia

The purpose of this study was to evaluate the utility of a novel organ dysfunction assessment score developed for patients with severe traumatic brain injury during therapeutic brain hypothermia. The Brain Hypothermia Organ Dysfunction Assessment (BHODA) score is calculated through the combined assessment of 6 indices: central nervous system (CNS) function, respiratory function, cardiovascular function, hepatosplanchnic circulation, coagulation, and metabolism. The CNS, hepatosplanchnic circulation, and metabolic indices were based on measurements of cerebral perfusion pressure, gastric tonometry, and blood glucose, respectively. Thirty-nine patients with severe closed head injuries (scores of 3 to 8 on the Glasgow Coma Scale) were enrolled. Seven patients (18%) died during hospitalization. Outcome was favorable in 20 patients and unfavorable in 19. The BHODA score proved useful in describing sequences of complications during therapeutic brain hypothermia. A total maximum BHODA score of more than 13 points corresponded to a mortality of 70%. In a multivariate model, the total maximum BHODA score was independently associated with neurological outcome (odds ratio for unfavorable neurological outcome, 2.590: 95% confidence interval, 1.260, 5.327). In conclusion, the BHODA score can help assess multiple organ dysfunction/failure during therapeutic hypothermia and may be useful for predicting outcome.

Systemic complications of neurologic diseases

The systemic complications associated with neurologic disease constitute an extensive topic, because the central nervous system controls many of the functions of the other organ systems in the body and because the brain cannot live in isolation of these systems. The precise mechanisms of many of these systemic alterations are poorly understood, but they appear to depend on the location and the severity of the initial central nervous system pathologic lesion.

Monitoring tissue oxygenation during resuscitation of major burns

BACKGROUND

Because subcutaneous and splanchnic oxygenation indices are sensitive indicators of evolving hemorrhagic shock and adequacy of resuscitation, we postulated that these indices might have an equivalent role in the monitoring of severely burned patients. This observational study was undertaken to examine changes in tissue oxygenation indices during burn resuscitation.

METHODS

Seven patients with major burns (54 +/- 21% total body surface area) were studied during the first 36 hours of fluid resuscitation. Silastic tubing was placed in the subcutaneous tissue just beneath both normal skin and deep partial thickness burn. Fiberoptic sensors inserted into the tubing measured subcutaneous oxygen and carbon dioxide tensions in the burnt skin (PO2scb and PCO2scb) and normal skin (PO2scn and PCO2scn) continuously. Gastric intramucosal pH (pHi) and the mucosal CO2 (PCO2m) gap were calculated using gastric tonometers. Mean arterial pressure, arterial pH, lactate, and pHi measurements were obtained for 36 hours.

RESULTS

There were no significant differences in mean arterial pressure, arterial pH, or lactate concentrations throughout the study period, whereas indices of tissue oxygenation showed deterioration: pHi decreased from 7.2 +/- 0.1 to 6.7 +/- 0.3 (p = 0.06), the PCO2m gap increased from 12 +/- 17 to 108 +/- 123 mm Hg (p < 0.01), PO2scn decreased from 112 +/- 18 to 50 +/- 11 mm Hg (p < 0.01), PO2scb decreased from 62 +/- 23 to 29 +/- 16 mm Hg (p < 0.01), PCO2scn increased from 42 +/- 4 to 46 +/- 10 mm Hg (p = 0.2), and PCO2scb increased from 42 +/- 10 to 52 +/- 5 mm Hg (p = 0.05).

CONCLUSION

Despite adequate global indices of tissue perfusion after 36 hours of resuscitation, tissue monitoring indicated significant deterioration in the splanchnic circulation and in the normal and burnt skin.

Acute care management of severe traumatic brain injuries

Preservation or restoration of optimal neurologic function following traumatic brain injury (TBI) requires timely and aggressive therapeutic interventions. Effective diagnostic tools, together with an armamentarium of treatment modalities, have augmented the treatment strategies utilized today. In addition, the Guidelinesfor the Management of Severe Head Injury have established a standardized approach for the TBI patient. This article will provide current information regarding the resuscitation priorities, appropriate interventions, and pharmacological agents used in the treatment required by the complex nature of TBI. Also, a review of the occurrences associated with TBI will be discussed.

The early assessment and intensive care unit management of patients with severe traumatic brain and spinal cord injuries

The assessment and management of neurotrauma have progressed significantly over the past several years. Improved understanding of the physiology of injured neural tissue and advances in technology have refined the approach to the care of patients suffering neurologic injury. Evidence-based clinical management guidelines, such as those developed by the Brain Trauma Foundation and the American Association of Neurological Surgeons, for the management of traumatic brain injury have been introduced to standardize certain aspects of care. The ongoing evolution of critical care also has had a significant impact on the care of patients suffering from neurotrauma. This article reviews some current issues related to the diagnosis and management of traumatic brain injury and spinal cord injury as we head into the next millennium.