Intravenous fluids in traumatic brain injury: what's the solution?

Traumatic brain injury: Symptoms to systems in the 21st century

Severe traumatic brain injury (TBI) is a devastating injury with a mortality of ∼ 25-30 %. Despite decades of high-quality research, no drug therapy has reduced mortality. Why is this so? We argue two contributing factors for the lack of effective drug therapies include the use of specific-pathogen free (SPF) animals for translational research and the flawed practice of single-nodal targeting for drug design. A revolution is required to better understand how the whole body responds to TBI, identify new markers of its progression, and discover new system-acting drugs to treat it. In this review, we present a brief history of TBI, discuss its system's pathophysiology and propose a new research strategy for the 21st century. TBI progression develops from injury signals radiating from the primary impact, which can cause local ischemia, hemorrhage, excitotoxicity, cellular depolarization, immune dysfunction, sympathetic hyperactivity, blood brain barrier breach, coagulopathy and whole-body dysfunction. Metabolic reprograming of immune cells drives neuroinflammation and secondary injury processes. We propose if sympathetic hyperactivity and immune cell activation can be corrected early, cardiovascular function and endothelial-glycocalyx-mitochondrial coupling can be restored, and secondary injury minimized with improved patient outcomes. The therapeutic goal is to switch the injury phenotype to a healing phenotype by restoring homeostasis and maintaining sufficient tissue O2 delivery. We have been developing a small-volume fluid therapy comprising adenosine, lidocaine and magnesium (ALM) to treat TBI and have shown that it blunts the CNS-stress response, supports cardiovascular function and reduces secondary injury. Future research will investigate its suitability for human translation.

Albumin in Normovolemic Fluid Management for Severe Traumatic Brain Injury: Controversies and Research Gaps

Traumatic brain injury (TBI) is a significant public health issue characterized by high mortality rates and long-term complications. This commentary examines the controversial role of the use of albumin in the fluid management of patients with severe TBI. Despite its physiological benefits, the clinical use of albumin remains controversial due to the fact that various studies have yielded mixed results. Serum albumin is important for maintaining normovolemia, primarily through its contribution to colloid osmotic pressure, which helps to retain fluid in the circulatory system. This review highlights the existing evidence, examines inconsistencies in guideline recommendations, and suggests future research directions to clarify the efficacy and safety of the use of albumin in maintaining normovolemia in patients with TBI. The review also discusses the potential benefits of small-volume resuscitation strategies for the management of acute kidney injury in TBI patients, drawing parallels with the management of septic acute kidney injury. The need for further well-designed randomized controlled trials and ethical considerations in studies regarding the use of hyperoncotic albumin in TBI management is emphasized.

In vivo calibration of genetically encoded metabolite biosensors must account for metabolite metabolism during calibration and cellular volume

Isotopic assays of brain glucose utilization rates have been used for more than four decades to establish relationships between energetics, functional activity, and neurotransmitter cycling. Limitations of these methods include the relatively long time (1-60 min) for the determination of labeled metabolite levels and the lack of cellular resolution. Identification and quantification of fuels for neurons and astrocytes that support activation and higher brain functions are a major, unresolved issues. Glycolysis is preferentially up-regulated during activation even though oxygen level and supply are adequate, causing lactate concentrations to quickly rise during alerting, sensory processing, cognitive tasks, and memory consolidation. However, the fate of lactate (rapid release from brain or cell-cell shuttling coupled with local oxidation) is long disputed. Genetically encoded biosensors can determine intracellular metabolite concentrations and report real-time lactate level responses to sensory, behavioral, and biochemical challenges at the cellular level. Kinetics and time courses of cellular lactate concentration changes are informative, but accurate biosensor calibration is required for quantitative comparisons of lactate levels in astrocytes and neurons. An in vivo calibration procedure for the Laconic lactate biosensor involves intracellular lactate depletion by intravenous pyruvate-mediated trans-acceleration of lactate efflux followed by sensor saturation by intravenous infusion of high doses of lactate plus ammonium chloride. In the present paper, the validity of this procedure is questioned because rapid lactate-pyruvate interconversion in blood, preferential neuronal oxidation of both monocarboxylates, on-going glycolytic metabolism, and cellular volumes were not taken into account. Calibration pitfalls for the Laconic lactate biosensor also apply to other metabolite biosensors that are standardized in vivo by infusion of substrates that can be metabolized in peripheral tissues. We discuss how technical shortcomings negate the conclusion that Laconic sensor calibrations support the existence of an in vivo astrocyte-neuron lactate concentration gradient linked to lactate shuttling from astrocytes to neurons to fuel neuronal activity.

Isotonic balanced fluid versus 0.9% saline in patients with moderate to severe traumatic brain injury: A double-blinded randomised controlled trial

BACKGROUND AND IMPORTANCE

Traumatic brain injury (TBI) is a global health concern with significant economic impact. Optimal fluid therapy aims to restore intravascular volume, maintain cerebral perfusion pressure and blood flow, thus preventing secondary brain injury. While 0.9% saline (NS) is commonly used, concerns about acid-base and electrolyte imbalance and development of acute kidney injury (AKI) lead to consideration of balanced fluids as an alternative.

OBJECTIVES

This study aimed to compare the outcomes of patients with moderate to severe TBI treated with Sterofundin (SF) versus NS.

DESIGN, SETTINGS AND PARTICIPANTS

A double-blinded randomised controlled trial of patients aged 18 to 65 years with TBI was conducted at the University Malaya Medical Centre from February 2017 to November 2019.

INTERVENTION OR EXPOSURE

Patients were randomly assigned to receive either NS or SF. The study fluids were administered for 72 h as continuous infusions or boluses. Participants, investigators, and staff were blinded to the fluid type.

OUTCOMES MEASURE AND ANALYSIS

The primary outcome was in-hospital mortality. Relative risk (RR) with 95% confidence interval (CI) was calculated.

MAIN RESULTS

A total of 70 patients were included in the analysis, with 38 in the NS group and 32 in the SF group. The in-hospital mortality rate were 3 (7.9%) in the NS group vs. 4 (12.5%) in the SF group, RR = 1.29 (95% CI, 0.64 to 2.59; p = 0.695). No patients developed AKI and required renal replacement therapy. ICP on day 3 was significantly higher in the SF group (18.60 ± 9.26) compared to 12.77 ± 3.63 in the NS group, (95% CI, -11.46 to 0.20; p = 0.037). There were no significant differences in 3-day biochemical parameters and cerebral perfusion pressure, ventilator-free days, length of ICU stay, or Glasgow Outcome Scale-Extended (GOS-E) score at 6 months.

CONCLUSIONS

In patients with moderate to severe TBI, the use of SF was not associated with reduced in-hospital mortality, development of AKI, or improved 6-month GOS-E when compared to NS.

Can a Therapeutic Strategy for Hypotension Improve Cerebral Perfusion and Oxygenation in an Experimental Model of Hemorrhagic Shock and Severe Traumatic Brain Injury?

BACKGROUND

Restoration of brain tissue perfusion is a determining factor in the neurological evolution of patients with traumatic brain injury (TBI) and hemorrhagic shock (HS). In a porcine model of HS without neurological damage, it was observed that the use of fluids or vasoactive drugs was effective in restoring brain perfusion; however, only terlipressin promoted restoration of cerebral oxygenation and lower expression of edema and apoptosis markers. It is unclear whether the use of vasopressor drugs is effective and beneficial during situations of TBI. The objective of this study is to compare the effects of resuscitation with saline solution and terlipressin on cerebral perfusion and oxygenation in a model of TBI and HS.

METHODS

Thirty-two pigs weighing 20-30 kg were randomly allocated into four groups: control (no treatment), saline (60 ml/kg of 0.9% NaCl), terlipressin (2 mg of terlipressin), and saline plus terlipressin (20 ml/kg of 0.9% NaCl + 2 mg of terlipressin). Brain injury was induced by lateral fluid percussion, and HS was induced through pressure-controlled bleeding, aiming at a mean arterial pressure (MAP) of 40 mmHg. After 30 min of circulatory shock, resuscitation strategies were initiated according to the group. The systemic and cerebral hemodynamic and oxygenation parameters, lactate levels, and hemoglobin levels were evaluated. The data were subjected to analysis of variance for repeated measures. The significance level established for statistical analysis was p < 0.05.

RESULTS

The terlipressin and saline plus terlipressin groups showed an increase in MAP that lasted until the end of the experiment (p < 0.05). There was a notable increase in intracranial pressure in all groups after starting treatment for shock. Cerebral perfusion pressure and cerebral oximetry showed no improvement after hemodynamic recovery in any group. The groups that received saline at resuscitation had the lowest hemoglobin concentrations after treatment.

CONCLUSIONS

The treatment of hypotension in HS with saline and/or terlipressin cannot restore cerebral perfusion or oxygenation in experimental models of HS and severe TBI. Elevated MAP raises intracranial pressure owing to brain autoregulation dysfunction caused by TBI.

Lactate shuttling as an allostatic means of thermoregulation in the brain

Lactate, the redox-balanced end product of glycolysis, travels within and between cells to fulfill an array of physiologic functions. While evidence for the centrality of this lactate shuttling in mammalian metabolism continues to mount, its application to physical bioenergetics remains underexplored. Lactate represents a metabolic "cul-de-sac," as it can only re-enter metabolism by first being converted back to pyruvate by lactate dehydrogenase (LDH). Given the differential distribution of lactate producing/consuming tissues during metabolic stresses (e.g., exercise), we hypothesize that lactate shuttling vis-à-vis the exchange of extracellular lactate between tissues serves a thermoregulatory function, i.e., an allostatic strategy to mitigate the consequences of elevated metabolic heat. To explore this idea, the rates of heat and respiratory oxygen consumption in saponin-permeabilized rat cortical brain samples fed lactate or pyruvate were measured. Heat and respiratory oxygen consumption rates, and calorespirometric ratios were lower during lactate vs. pyruvate-linked respiration. These results support the hypothesis of allostatic thermoregulation in the brain with lactate.

Kidney Dysfunction After Traumatic Brain Injury: Pathophysiology and General Management

Traumatic brain injury (TBI) remains a major cause of mortality and morbidity, and almost half of these patients are admitted to the intensive care unit. Of those, 10% develop acute kidney injury (AKI) and 2% even need kidney replacement therapy (KRT). Although clinical trials in patients with TBI who have AKI are lacking, some general principles in this population may apply. The present review is an overview on the epidemiology and pathophysiology of AKI in patients with TBI admitted to the intensive care unit who are at risk for or who have developed AKI. A cornerstone in severe TBI management is preventing secondary brain damage, in which reducing the intracranial pressure (ICP) and optimizing the cerebral perfusion pressure (CPP) remain important therapeutic targets. To treat episodes of elevated ICP, osmolar agents such as mannitol and hypertonic saline are frequently administered. Although we are currently awaiting the results of a prospective randomized controlled trial that compares both agents, it is important to realize that both agents have been associated with an increased risk of developing AKI which is probably higher for mannitol compared with hypertonic saline. For the brain, as well as for the kidney, targeting an adequate perfusion pressure is important. Hemodynamic management based on the combined use of intravascular fluids and vasopressors is ideally guided by hemodynamic monitoring. Hypotonic albumin or crystalloid resuscitation solutions may increase the risk of brain edema, and saline-based solutions are frequently used but have a risk of hyperchloremia, which might jeopardize kidney function. In patients at risk, frequent assessment of serum chloride might be advised. Maintenance of an adequate CPP involves the optimization of circulating blood volume, often combined with vasopressor agents. Whether individualized CPP targets based on cerebrovascular autoregulation monitoring are beneficial need to be further investigated. Interestingly, such individualized perfusion targets are also under investigation in patients as a strategy to mitigate the risk for AKI in patients with chronic hypertension. In the small proportion of patients with TBI who need KRT, continuous techniques are advised based on pathophysiology and expert opinion. The need for KRT is associated with a higher risk of intracranial hypertension, especially if osmolar clearance occurs fast, which can even occur in continuous techniques. Precise ICP and CPP monitoring is mandatory, especially at the initiation of KRT.

Perioperative Fluid Management in Surgical Patients: A Review

Intravenous (IV) fluids are one of the most widely prescribed medications. Despite their frequent usage, IV fluids are often not used appropriately. High-quality evidence to guide the surgeon in the perioperative period is sparse. A plethora of choices for IV fluids exists with limited evidence to help guide the surgeon in specific patient populations and situations. To address this, the authors have set out to provide a critical review of commonly used IV fluids to treat surgical patients. Gaps in the existing literature for the surgical population will also be discussed as potential target areas for future research.

Use of Hyperoncotic Human Albumin Solution in Severe Traumatic Brain Injury Revisited-A Narrative Review and Meta-Analysis

A significant proportion of patients with a severe traumatic brain injury (TBI) have hypoalbuminemia and require fluid resuscitation. Intravenous fluids can have both favorable and unfavorable consequences because of the risk of hyperhydration and hypo- or hyperosmolar conditions, which may affect the outcome of a TBI. Fluid resuscitation with human albumin solution (HAS) corrects low serum albumin levels and aids in preserving euvolemia in non-brain-injured intensive care units and in perioperative patients. However, the use of HAS for TBI remains controversial. In patients with TBI, the infusion of hypooncotic (4%) HAS was associated with adverse outcomes. The side effects of 4% HAS and the safety and efficacy of hyperoncotic (20-25%) HAS used in the Lund concept of TBI treatment need further investigation. A nonsystematic review, including a meta-analysis of controlled clinical trials, was performed to evaluate hyperoncotic HAS in TBI treatment. For the meta-analysis, the MEDLINE and EMBASE Library databases, as well as journal contents and reference lists, were searched for pertinent articles up to March 2021. Four controlled clinical studies involving 320 patients were included. The first was a randomized trial. Among 165 patients treated with hyperoncotic HAS, according to the Lund concept, 24 (14.5%) died vs. 59 out of 155 control patients (38.1%). A Lund concept intervention using hyperoncotic HAS was associated with a significantly reduced mortality (p = 0.002). Evidence of the beneficial effects of fluid management with hyperoncotic HAS on mortality in patients with TBI is at a high risk of bias. Prospective randomized controlled trials are required, which could lead to changes in clinical practice recommendations for fluid management in patients with TBI.

Hypertonic lactate for the treatment of intracranial hypertension in patients with acute brain injury

Hypertonic lactate (HL) is emerging as alternative treatment of intracranial hypertension following acute brain injury (ABI), but comparative studies are limited. Here, we examined the effectiveness of HL on main cerebral and systemic physiologic variables, and further compared it to that of standard hypertonic saline (HS). Retrospective cohort analysis of ABI subjects who received sequential osmotherapy with 7.5% HS followed by HL-given at equi-osmolar (2400 mOsmol/L) and isovolumic (1.5 mL/kg) bolus doses-to reduce sustained elevations of ICP (> 20 mmHg). The effect of HL on brain (intracranial pressure [ICP], brain tissue PO₂ [PbtO₂], cerebral microdialysis [CMD] glucose and lactate/pyruvate ratio [LPR]) and blood (chloride, pH) variables was examined at different time-points (30, 60, 90, 120 min vs. baseline), and compared to that of HS. A total of 34 treatments among 17 consecutive subjects (13 traumatic brain injury [TBI], 4 non-TBI) were studied. Both agents significantly reduced ICP (p < 0.001, at all time-points tested): when comparing treatment effectiveness, absolute ICP decrease in mmHg and the duration of treatment effect (median time with ICP < 20 mmHg following osmotherapy 183 [108-257] vs. 150 [111-419] min) did not differ significantly between HL and HS (all p > 0.2). None of the treatment had statistically significant effects on PbtO₂ and CMD biomarkers. Treatment with HL did not cause hyperchloremia and resulted in a more favourable systemic chloride balance than HS (Δ blood chloride - 1 ± 2.5 vs. + 4 ± 3 mmol/L; p < 0.001). This is the first clinical study showing that HL has comparative effectiveness than HS for the treatment of intracranial hypertension, while at the same time avoiding hyperchloremic acidosis. Both agents had no significant effect on cerebral oxygenation and metabolism.

Lactate infusion as therapeutical intervention: a scoping review

Traditionally, clinicians consider lactate as a waste product of anaerobic glycolysis. Interestingly, research has shown that lactate may serve as an alternative fuel for the brain to protect it against harm. The increasing scientific awareness of the potential beneficial side of lactate, however, is entering the clinic rather slowly. Following this, and realizing that the application of potential novel therapeutic strategies in pediatric populations often lags behind the development in adults, this review summarizes the key data on therapeutic use of intravenous infusion of sodium lactate in humans. PubMed and clinicaltrial.gov were searched up until November 2021 focusing on interventional studies in humans. Thirty-four articles were included in this review, with protocols of lactate infusion in adults with diabetes mellitus, traumatic brain injury, Alzheimer's disease, and cardiac disease. One study on lactate infusion in children was also included. Results of our literature search show that sodium lactate can be safely administrated, without major side effects. Additionally, the present literature clearly shows the potential benefits of therapeutic lactate infusion under certain pathological circumstances, including rather common clinical conditions like traumatic brain injury.

CONCLUSION

This review shows that lactate is a save, alternative energy source for the adult brain warranting studies on the potential therapeutic effects of sodium lactate infusion in children.

WHAT IS KNOWN

• Lactate is generally considered a waste product of anaerobic glycolysis. However, lactate also is an alternative fuel for different organs, including the brain. • Lactate infusion is not incorporated in standard care for any patient population.

WHAT IS NEW

• Thirty-four studies investigated the therapeutic use of intravenous sodium lactate in different patient populations, all with different study protocols. • Literature shows that lactate infusion may have beneficial effects in case of hypoglycemia, traumatic brain injury, and cardiac failure without the risk of major side effects.

Traumatic Brain Injury-A Review of Intravenous Fluid Therapy

This manuscript will review intravenous fluid therapy in traumatic brain injury. Both human and animal literature will be included. Basic treatment recommendations will also be discussed.

Prehospital Whole Blood Resuscitation Reduces Fluid Requirement While Maintaining Critical Physiology in a Model of Penetrating Traumatic Brain Injury and Hemorrhage: Implications on Resource-Limited Combat Casualty Care

ABSTRACT

Prehospital resuscitation using whole blood (WB) is the standard of care for hemorrhagic shock (HS) but there is no consensus recommendation for resuscitation in the presence of traumatic brain injury (TBI) due to a lack of sufficient evidence. In order to evaluate the optimal resuscitation strategies for TBI+HS, Sprague-Dawley rats were randomized into four groups based on resuscitation fluid and prehospital mean arterial pressure (MAP) threshold (n = 9-10/group): Lactated Ringer's (LR)-60 mm Hg (LR60), LR-70 mm Hg (LR70), WB-60 mm Hg (WB60), WB-70 mm Hg (WB70). All groups received a frontal penetrating ballistic-like brain injury followed by a 35-min period of HS. During the prehospital phase, rats received an initial bolus of resuscitation fluid (WB or LR) followed by LR as needed to maintain MAP above the designated threshold for 90 min. During the in-hospital phase, rats received definitive resuscitation with shed WB. Physiological parameters were recorded continuously and cerebral edema was measured at 3 and 24 h postinjury. The WB60 group demonstrated a significantly lower prehospital fluid requirement compared WB70, LR60, and LR70 (P < 0.05). Compared to the respective LR groups, both the WB60 and WB70 groups also demonstrated improved MAP, cerebral perfusion pressure, brain tissue oxygen tension, and cerebral edema. The edema benefits were observed at 3 h, but not 24 h postinjury, and were localized to the injury site. Together, these results provide evidence that prehospital WB resuscitation and lower MAP resuscitation thresholds can reduce the prehospital fluid requirement while still maintaining critical cerebral physiology in a model of HS and concomitant TBI.

Effect of hypertonic saline in the management of elevated intracranial pressure in children with cerebral edema: A systematic review and meta-analysis

Objective:

To determine the hypertonic saline efficacy in children with cerebral edema and raised intracranial pressure.

Method:

Studies assessing the efficacy and safety of hypertonic saline in children with cerebral edema and elevated intracranial pressure were identified using Medline, Web of Science, Scopus, and Google Scholar databases. Two reviewers independently assessed papers for inclusion. The primary outcome was a reduction of elevated intracranial pressure by the administration of hypertonic saline.

Results:

We initially evaluated 1595 potentially relevant articles, and only 7 studies met the eligibility criteria for the final analysis. Out of the seven studies, three of them were randomized controlled trials. Three of the studies found that hypertonic saline significantly reduced elevated intracranial pressure compared to control. One study reported a resolution of the comatose state as a measure of reduced intracranial pressure. It also found a significantly higher resolution of coma in the hypertonic saline group rather than the control. Three studies reported that the reduction of intracranial pressure was comparable between the groups. The random-effects model using pooled estimates from four studies showed no difference in hypertonic saline and conventional therapy mortality outcomes. Hypertonic saline was administered as bolus-only therapy at a rate of 1–10 mL/kg/dose over 5 min to 2 h and or bolus followed by infusion therapy (0.5–2 mL/kg/h). One study reported a twofold faster resolution of high intracranial pressure following hypertonic saline administration compared to controls. The re-dosing schedule varied greatly in all included studies. However, three studies reported adverse events but not methodically, and there were no reports on neurological sequelae.

Conclusion:

Hypertonic saline appears to reduce intracranial pressure in children with cerebral edema. However, we cannot draw a firm conclusion regarding the safest dose regimens of hypertonic saline, including the safe and effective therapeutic hypernatremia threshold in the management of raised intracranial pressure with cerebral edema. Future clinical trials should focus on the appropriate concentration, dose, duration, mode of administration, and adverse effects of hypertonic saline to standardize the treatment.

Mortality following combined burn and traumatic brain injuries: An analysis of the national trauma data bank of the American College of Surgeons

BACKGROUND

Severe burn and traumatic brain injuries (TBI) lead to significant mortality, and combined burn-TBI injuries may predispose towards even worse outcomes. The purpose of this study was to investigate the mortality of patients with burn, burn with non-TBI trauma, and combined burn/TBI to determine if combined injury portends a worse outcome.

METHODS

We obtained the National Trauma Data Bank from 2007 to 2012, identifying 32,334 patients with burn related injuries, dividing this cohort into three injury types: BURN ONLY, BURN with TRAUMA/NO TBI, and BURN with TBI. For each patient, demographic data was obtained, including age, gender, presence of trauma, TBI, or inhalation injury, burn total body surface area (TBSA), Glasgow Coma Scale, Injury Severity Score, and mortality. Multivariable logistic regression was performed.

RESULTS

Age, gender, and TBSA were similar across the three injury groups, but the incidence of inhalation injury was doubled in the BURN with TRAUMA/NO TBI (15.4 %) and BURN with TBI (15.3 %) groups when compared to the BURN ONLY (7.2 %) group. Mortality differed across injury categories after adjusting for age, TBSA, and inhalation injury. Increased mortality was seen in BURN with TRAUMA/NO TBI versus BURN ONLY (OR = 1.27 [1.06, 1.53]) and was higher when comparing BURN with TBI versus BURN ONLY (OR = 4.22 [2.85, 6.18]). BURN with TBI also had higher mortality when compared to BURN with TRAUMA/NO TBI (OR = 3.33 [2.30, 4.82]). The logs odds of mortality also increased with increasing age, TBSA and presence of inhalation injury.

DISCUSSION

This analysis of the NTDB suggests that mortality following burn-related injuries may be higher when burn injury is combined with TBI when compared to burns with other trauma, even after correcting for age, TBSA, and inhalation injury. Further clinical and laboratory research is needed to validate these findings and better understand how to optimize combined TBI and burn injury treatment.

Guidelines for safe transfer of the brain-injured patient: trauma and stroke, 2019: Guidelines from the Association of Anaesthetists and the Neuro Anaesthesia and Critical Care Society

The location of care for many brain-injured patients has changed since 2012 following the development of major trauma centres. Advances in management of ischaemic stroke have led to the urgent transfer of many more patients. The basis of care has remained largely unchanged, however, with emphasis on maintaining adequate cerebral perfusion as the key to preventing secondary injury. Organisational aspects and training for transfers are highlighted, and we have included an expanded section on paediatric transfers. We have also provided a table with suggested blood pressure parameters for the common types of brain injury but acknowledge that there is little evidence for many of our recommendations. These guidelines remain a mix of evidence-based and consensus-based statements. We have received assistance from many organisations representing clinicians who care for these patients, and we believe our views represent the best of current thinking and opinion. We encourage departments to review their own practice using our suggestions for audit and quality improvement.

Hypertonic Lactate to Improve Cerebral Perfusion and Glucose Availability After Acute Brain Injury

OBJECTIVES

Lactate promotes cerebral blood flow and is an efficient substrate for the brain, particularly at times of glucose shortage. Hypertonic lactate is neuroprotective after experimental brain injury; however, human data are limited.

DESIGN

Prospective study (clinicaltrials.gov NCT01573507).

SETTING

Academic ICU.

PATIENTS

Twenty-three brain-injured subjects (13 traumatic brain injury/10 subarachnoid hemorrhage; median age, 59 yr [41-65 yr]; median Glasgow Coma Scale, 6 [3-7]).

INTERVENTIONS

Three-hour IV infusion of hypertonic lactate (sodium lactate, 1,000 mmol/L; concentration, 30 µmol/kg/min) administered 39 hours (26-49 hr) from injury.

MEASUREMENTS AND MAIN RESULTS

We examined the effect of hypertonic lactate on cerebral perfusion (using transcranial Doppler) and brain energy metabolism (using cerebral microdialysis). The majority of subjects (13/23 = 57%) had reduced brain glucose availability (baseline pretreatment cerebral microdialysis glucose, < 1 mmol/L) despite normal baseline intracranial pressure (10 [7-15] mm Hg). Hypertonic lactate was associated with increased cerebral microdialysis lactate (+55% [31-80%]) that was paralleled by an increase in middle cerebral artery mean cerebral blood flow velocities (+36% [21-66%]) and a decrease in pulsatility index (-21% [13-26%]; all p < 0.001). Cerebral microdialysis glucose increased above normal range during hypertonic lactate (+42% [30-78%]; p < 0.05); reduced brain glucose availability correlated with a greater improvement of cerebral microdialysis glucose (Spearman r = -0.53; p = 0.009). No significant changes in cerebral perfusion pressure, mean arterial pressure, systemic carbon dioxide, and blood glucose were observed during hypertonic lactate (all p > 0.1).

CONCLUSIONS

This is the first clinical demonstration that hypertonic lactate resuscitation improves both cerebral perfusion and brain glucose availability after brain injury. These cerebral vascular and metabolic effects appeared related to brain lactate supplementation rather than to systemic effects.

Fluid Management in Acute Brain Injury

PURPOSE OF THE REVIEW

The aims of fluid management in acute brain injury are to preserve or restore physiology and guarantee appropriate tissue perfusion, avoiding potential iatrogenic effects. We reviewed the literature, focusing on the clinical implications of the selected papers. Our purposes were to summarize the principles regulating the distribution of water between the intracellular, interstitial, and plasma compartments in the normal and the injured brain, and to clarify how these principles could guide fluid administration, with special reference to intracranial pressure control.

RECENT FINDINGS

Although a considerable amount of research has been published on this topic and in general on fluid management in acute illness, the quality of the evidence tends to vary. Intravascular volume management should aim for euvolemia. There is evidence of harm with aggressive administration of fluid aimed at achieving hypervolemia in cases of subarachnoid hemorrhage. Isotonic crystalloids should be the preferred agents for volume replacement, while colloids, glucose-containing hypotonic solutions, and other hypotonic solutions or albumin should be avoided. Osmotherapy seems to be effective in intracranial hypertension management; however, there is no clear evidence regarding the superiority of hypertonic saline over mannitol. Fluid therapy plays an important role in the management of acute brain injury patients. However, fluids are a double-edged weapon because of the potential risk of hyper-hydration, hypo- or hyper-osmolar conditions, which may unfavorably affect the clinical course and the outcome.

Pathophysiology and Management of Intracranial Hypertension and Tissular Brain Hypoxia After Severe Traumatic Brain Injury: An Integrative Approach

Monitoring intracranial pressure in comatose patients with severe traumatic brain injury (TBI) is considered necessary by most experts. Acute intracranial hypertension (IHT), when severe and sustained, is a life-threatening complication that demands emergency treatment. Yet, secondary anoxic-ischemic injury after brain trauma can occur in the absence of IHT. In such cases, adding other monitoring modalities can alert clinicians when the patient is in a state of energy failure. This article reviews the mechanisms, diagnosis, and treatment of IHT and brain hypoxia after TBI, emphasizing the need to develop a physiologically integrative approach to the management of these complex situations.

Sodium lactate improves renal microvascular thrombosis compared to sodium bicarbonate and 0.9% NaCl in a porcine model of endotoxic shock: an experimental randomized open label controlled study

Background

Sodium lactate seemed to improve fluid balance and avoid fluid overload. The objective of this study was to determine if these beneficial effects can be at least partly explained by an improvement in disseminated intravascular coagulation (DIC)-associated renal microvascular thrombosis.

Methods

Ancillary work of an interventional randomized open label controlled experimental study. Fifteen female “Large White” pigs (2 months old) were challenged with intravenous infusion of E. coli endotoxin. Three groups of five animals were randomly assigned to receive different fluids: a treatment group received sodium lactate 11.2% (SL group); an isotonic control group received 0.9% NaCl (NC group); a hypertonic control group, with the same amount of osmoles and sodium than SL group, received sodium bicarbonate 8.4% (SB group). Glomerular filtration rate (GFR) markers, coagulation and inflammation parameters were measured over a 5-h period. Immediately after euthanasia, kidneys were withdrawn for histological study. Statistical analysis was performed with nonparametric tests and the Dunn correction for multiple comparisons. A p < 0.05 was considered significant.

Results

The direct immunofluorescence study revealed that the percentage of capillary sections thrombosed in glomerulus were significantly lesser in SL group [5 (0–28) %] compared to NC [64 (43–79) %, p = 0.01] and SB [64 (43–79), p = 0.03] groups. Alterations in platelet count and fibrinogen level occurred earlier and were significantly more pronounced in both control groups compared to SL group (p < 0.05 at 210 and 300 min). The increase in thrombin–antithrombin complexes was significantly higher in NC [754 (367–945) μg/mL; p = 0.03] and SB [463 (249–592) μg/mL; p = 0.03] groups than in SL group [176 (37–265) μg/mL]. At the end of the experiment, creatinine clearance was significantly higher in SL group [55.46 (30.07–67.85) mL/min] compared to NC group [1.52 (0.17–27.67) mL/min, p = 0.03].

Conclusions

In this study, we report that sodium lactate improves DIC-associated renal microvascular thrombosis and preserves GFR. These findings could at least partly explain the better fluid balance observed with sodium lactate infusion.

Acute respiratory distress syndrome in traumatic brain injury: how do we manage it?

Traumatic brain injury (TBI) is an important cause of morbidity and mortality worldwide. TBI patients frequently suffer from lung complications and acute respiratory distress syndrome (ARDS), which is associated with poor clinical outcomes. Moreover, the association between TBI and ARDS in trauma patients is well recognized. Mechanical ventilation of patients with a concomitance of acute brain injury and lung injury can present significant challenges. Frequently, guidelines recommending management strategies for patients with traumatic brain injuries come into conflict with what is now considered best ventilator practice. In this review, we will explore the strategies of the best practice in the ventilatory management of patients with ARDS and TBI, concentrating on those areas in which a conflict exists. We will discuss the use of ventilator strategies such as protective ventilation, high positive end expiratory pressure (PEEP), prone position, recruitment maneuvers (RMs), as well as techniques which at present are used for 'rescue' in ARDS (including extracorporeal membrane oxygenation) in patients with TBI. Furthermore, general principles of fluid, haemodynamic and hemoglobin management will be discussed. Currently, there are inadequate data addressing the safety or efficacy of ventilator strategies used in ARDS in adult patients with TBI. At present, choice of ventilator rescue strategies is best decided on a case-by-case basis in conjunction with local expertise.

Uses and misuses of albumin during resuscitation and in the neonatal intensive care unit

Albumin is one of the most abundant proteins in plasma and serves many vital functions. Neonatal concentrations vary greatly with gestational and postnatal age. In critically ill neonates, hypoalbuminemia occurs due to decreased synthesis, increased losses or redistribution of albumin into the extravascular space, and has been associated with increased morbidities and mortality. For that reason, infusion of exogenous albumin as a volume expander has been proposed for various clinical settings including hypotension, delivery room resuscitation, sepsis and postoperative fluid management. Albumin is often prescribed in infants with hypoalbuminemia, hyperbilirubinemia, and protein-losing conditions. However, the evidence of these practices has not been reviewed or validated. Albumin infusion may initiate highly complex processes that vary according to the individual and disease pathophysiology. Indeed, it may be associated with harms when misused. In this review, we critically appraise the scientific evidence for administering albumin in most conditions encountered in the neonatal intensive care unit, while emphasizing the benefits and risks associated with their use.

Biomarkers of Physiological Disturbances for Predicting Mortality in Decompressive Craniectomy

Objective

Of many critical care regimens, the management of physiological disturbances in serum is particularly drawing an attention in conjunction with patient outcome. The aim of this study was to assess the association of serum biochemical markers with mortality in head trauma patients with decompressive craniotomy.

Methods

Ninety six patients with acute subdural hematoma underwent decompressive craniectomy between January 2014 and December 2015. The clinical data and laboratory variables of these patients were recorded and analyzed retrospectively. The pre-operative and post-operative day (POD) 0, day 1 and day 2 serum variables were measured. These were compared between the survivors and non-survivors.

Results

The factors of a large amount of intra-operative blood loss, shorter length of intensive care unit stays, and the needs for mechanical ventilation were related with mortality in the patients with decompressive craniectomy. These clinical factors were associated with the physiological derangements of sera. The average difference in serum chloride concentration between the pre-operative and POD 2 measurements (p=0.0192) showed a statistical significance in distinguishing between survivors and non-survivors. The average differences in albumin (p=0.0011) and platelet count (p=0.0004) between the pre-operative and POD 0 measurements suggested to be strong predictors of mortality in decompressive craniectomy.

Conclusion

Isolated values of physiological biomarkers are not sufficient enough to predict in-hospital mortality. This study emphasizes the importance of a combined prognostic model of the differences in the pre-operative and post-operative hyperchloremia, thrombocytopenia, and hypoalbuminemia to identify the risk of mortality in decompressive craniecomy.

Fluid management of the neurological patient: a concise review

Maintenance fluids in critically ill brain-injured patients are part of routine critical care. Both the amounts of fluid volumes infused and the type and tonicity of maintenance fluids are relevant in understanding the impact of fluids on the pathophysiology of secondary brain injuries in these patients. In this narrative review, current evidence on routine fluid management of critically ill brain-injured patients and use of haemodynamic monitoring is summarized. Pertinent guidelines and consensus statements on fluid management for brain-injured patients are highlighted. In general, existing guidelines indicate that fluid management in these neurocritical care patients should be targeted at euvolemia using isotonic fluids. A critical appraisal is made of the available literature regarding the appropriate amount of fluids, haemodynamic monitoring and which types of fluids should be administered or avoided and a practical approach to fluid management is elaborated. Although hypovolemia is bound to contribute to secondary brain injury, some more recent data have emerged indicating the potential risks of fluid overload. However, it is acknowledged that many factors govern the relationship between fluid management and cerebral blood flow and oxygenation and more research seems warranted to optimise fluid management and improve outcomes.

Analysis of the association of fluid balance and short-term outcome in traumatic brain injury

INTRODUCTION

A balance of fluid intake and output (fluid balance) influences outcomes of critical illness, but the level of such influence remains poorly understood for traumatic brain injury (TBI) and was quantitatively examined in this study.

METHODS

We conducted a retrospective cohort study of 351 moderate and severe TBI patients to associate the degree of fluid balance with clinical outcomes of TBI. Fluid balance and intracranial pressure (ICP) were continuously recorded for 7days on patients admitted to neurocritical care unit (NCCU). The short-term outcome was dichotomized into improvement and deterioration groups based on changes in Glasgow Coma Scale (GCS) measured between admission and 30days after admission. Fluid balance was calculated as: Fluid intake (mL) - fluid outputs (mL)/day×5 and used to group patients in tertiles to study its effect on TBI outcome.

RESULTS

Patients at the low (<637mL) and upper (>3673mL) tertiles of fluid balance were associated with poor outcomes. Those in the upper tertile also had a higher incidence of acute kidney injury (AKI) and refractory intracranial hypertension (RIH). There was a negative correlation between the cumulative fluid balance and the short-term outcome for patients in the low tertile and a positive correlation between the cumulative fluid balance and the short-term outcome in the upper fluid balance group. Levels of fluid balance were also associated with serum creatinine (Cr, r=0.451, P<0.0001) and days in NCCU (r=0.188, P=0.001). More patients in the upper tertile had ICP higher than 20mmHg (P=0.009). A fluid balance in the upper tertile is an independent predictor of poor 30-day clinical outcomes after the adjustment for confounding variables in a multivariable logistic regression model.

CONCLUSION

We found that fluid balance in low and upper tertiles were associated with poor short-term outcomes and ICP variations. Fluid balance in the upper tertile may be an independent predictor for poor 30-day outcome, primarily due to high AKI and RIH.

Effect of volume replacement during combined experimental hemorrhagic shock and traumatic brain injury in prostanoids, brain pathology and pupil status

Traumatic brain injury (TBI) is the main cause of trauma-related deaths. Systemic hypotension and intracranial hypertension causes cerebral ischemia by altering metabolism of prostanoids. We describe prostanoid, pupilar and pathological response during resuscitation with hypertonic saline solution (HSS) in TBI. Method Fifteen dogs were randomized in three groups according to resuscitation after TBI (control group; lactated Ringer's (LR) group and HSS group), with measurement of thromboxane, prostaglandin, macroscopic and microscopic pathological evaluation and pupil evaluation.Result Concentration of prostaglandin is greater in the cerebral venous blood than in plasma and the opposite happens with concentration of thromboxane. Pathology revealed edema in groups with the exception of group treated with HSS.Discussion and conclusion There is a balance between the concentrations of prostaglandin and thromboxane. HSS prevented the formation of cerebral edema macroscopically detectable. Pupillary reversal occurred earlier in HSS group than in LR group.

Damage control resuscitation: lessons learned

BACKGROUND

Damage control resuscitation describes an approach to the early care of very seriously injured patients. The aim is to keep the patient alive whilst avoiding interventions and situations that risk worsening their situation by driving the lethal triad of hypothermia, coagulopathy and acidosis or excessively stimulating the immune-inflammatory system. It is critical that the concepts and practicalities of this approach are understood by all those involved in the early management of trauma patients. This review aims to summarise this and discusses current knowledge on the subject.

INTERVENTIONS

Damage control resuscitation forms part of an overall approach to patient care rather than a specific intervention and has evolved from damage control surgery. It is characterised by early blood product administration, haemorrhage arrest and restoration of blood volume aiming to rapidly restore physiologic stability. The infusion of large volumes of crystalloid is no longer appropriate, instead the aim is to replace lost blood and avoid dilution and coagulopathy. In specific situations, permissive hypotension may also be of benefit, particularly in patients with severe haemorrhage from an arterial source. As rapid arrest of haemorrhage is so important, team-based protocols that deliver patients rapidly but safely, via CT scan where appropriate, to operating theatres or interventional radiology suites form a critical part of this process.

CONCLUSIONS

Given that interventions are so time dependent in the severely injured, it is likely that by further improving trauma systems and protocols, improvements in outcome can still be made. Further research work in this area will allow us to target these approaches more accurately to those patients who can benefit most.

Critical Care for the Patient With Multiple Trauma

Trauma remains the leading cause of death worldwide and the leading cause of death in those less than 44 years old in the United States. Admission to a verified trauma center has been shown to decrease mortality following a major injury. This decrease in mortality has been a direct result of improvements in the initial evaluation and resuscitation from injury as well as continued advances in critical care. As such, it is vital that intensive care practitioners be familiar with various types of injuries and their associated treatment strategies as well as their potential complications in order to minimize the morbidity and mortality frequently seen in this patient population.

Evidence to support mitochondrial neuroprotection, in severe traumatic brain injury

Traumatic brain injury (TBI) is still the leading cause of disability in young adults worldwide. The major mechanisms - diffuse axonal injury, cerebral contusion, ischemic neurological damage, and intracranial hematomas have all been shown to be associated with mitochondrial dysfunction in some form. Mitochondrial dysfunction in TBI patients is an active area of research, and attempts to manipulate neuronal/astrocytic metabolism to improve outcomes have been met with limited translational success. Previously, several preclinical and clinical studies on TBI induced mitochondrial dysfunction have focused on opening of the mitochondrial permeability transition pore (PTP), consequent neurodegeneration and attempts to mitigate this degeneration with cyclosporine A (CsA) or analogous drugs, and have been unsuccessful. Recent insights into normal mitochondrial dynamics and into diseases such as inherited mitochondrial neuropathies, sepsis and organ failure could provide novel opportunities to develop mitochondria-based neuroprotective treatments that could improve severe TBI outcomes. This review summarizes those aspects of mitochondrial dysfunction underlying TBI pathology with special attention to models of penetrating traumatic brain injury, an epidemic in modern American society.