The implications of cerebral ischemia and metabolic dysfunction for treatment strategies in neurointensive care

Optimization of Nutrition after Brain Injury: Mechanistic and Therapeutic Considerations

Emerging science continues to establish the detrimental effects of malnutrition in acute neurological diseases such as traumatic brain injury, stroke, status epilepticus and anoxic brain injury. The primary pathological pathways responsible for secondary brain injury include neuroinflammation, catabolism, immune suppression and metabolic failure, and these are exacerbated by malnutrition. Given this, there is growing interest in novel nutritional interventions to promote neurological recovery after acute brain injury. In this review, we will describe how malnutrition impacts the biomolecular mechanisms of secondary brain injury in acute neurological disorders, and how nutritional status can be optimized in both pediatric and adult populations. We will further highlight emerging therapeutic approaches, including specialized diets that aim to resolve neuroinflammation, immunodeficiency and metabolic crisis, by providing pre-clinical and clinical evidence that their use promotes neurologic recovery. Using nutrition as a targeted treatment is appealing for several reasons that will be discussed. Given the high mortality and both short- and long-term morbidity associated with acute brain injuries, novel translational and clinical approaches are needed.

Nutrition Therapy, Glucose Control, and Brain Metabolism in Traumatic Brain Injury: A Multimodal Monitoring Approach

The goal of neurocritical care in patients with traumatic brain injury (TBI) is to prevent secondary brain damage. Pathophysiological mechanisms lead to loss of body mass, negative nitrogen balance, dysglycemia, and cerebral metabolic dysfunction. All of these complications have been shown to impact outcomes. Therapeutic options are available that prevent or mitigate their negative impact. Nutrition therapy, glucose control, and multimodality monitoring with cerebral microdialysis (CMD) can be applied as an integrated approach to optimize systemic immune and organ function as well as adequate substrate delivery to the brain. CMD allows real-time bedside monitoring of aspects of brain energy metabolism, by measuring specific metabolites in the extracellular fluid of brain tissue. Sequential monitoring of brain glucose and lactate/pyruvate ratio may reveal pathologic processes that lead to imbalances in supply and demand. Early recognition of these patterns may help individualize cerebral perfusion targets and systemic glucose control following TBI. In this direction, recent consensus statements have provided guidelines and recommendations for CMD applications in neurocritical care. In this review, we summarize data from clinical research on patients with severe TBI focused on a multimodal approach to evaluate aspects of nutrition therapy, such as timing and route; aspects of systemic glucose management, such as intensive vs. moderate control; and finally, aspects of cerebral metabolism. Research and clinical applications of CMD to better understand the interplay between substrate supply, glycemic variations, insulin therapy, and their effects on the brain metabolic profile were also reviewed. Novel mechanistic hypotheses in the interpretation of brain biomarkers were also discussed. Finally, we offer an integrated approach that includes nutritional and brain metabolic monitoring to manage severe TBI patients.

Hemoglobin thresholds and red blood cell transfusion in adult patients with moderate or severe traumatic brain injuries: A retrospective cohort study

PURPOSE

We aimed to evaluate the association between transfusion practices and clinical outcomes in patients with traumatic brain injury.

MATERIAL AND METHODS

We conducted a retrospective cohort study of adult patients with moderate or severe traumatic brain injury admitted to the intensive care unit (ICU) of a level I trauma center between 2009 and 2013. The associations between hemoglobin (Hb) level, red blood cell (RBC) transfusion and clinical outcomes were estimated using robust Poisson models and proportional hazard models with time-dependent variables, adjusted for confounders.

RESULTS

We included 215 patients. Sixty-six patients (30.7%) were transfused during ICU stay. The median pre-transfusion Hb among transfused patients was 81g/L (IQR 67-100), while median nadir Hb among non-transfused patients was 110g/L (IQR 93-123). Poor outcomes were significantly more frequent in patients who were transfused (mortality risk ratio [RR]: 2.15 [95% CI 1.37-3.38] and hazard ratio: 3.06 [95% CI 1.57-5.97]; neurological complications RR: 3.40 [95% CI 1.35-8.56]; trauma complications RR: 1.65 [95% CI 1.31-2.08]; ICU length of stay geometric mean ratio: 1.42 [95% CI 1.06-1.92]).

CONCLUSIONS

During ICU stay, transfused patients tended to have lower Hb levels and worse outcomes than patients who did not receive RBCs, after adjustment for confounders.

Resting functional imaging tools (MRS, SPECT, PET and PCT)

Functional imaging includes imaging techniques that provide information about the metabolic and hemodynamic status of the brain. Most commonly applied functional imaging techniques in patients with traumatic brain injury (TBI) include magnetic resonance spectroscopy (MRS), single photon emission computed tomography (SPECT), positron emission tomography (PET) and perfusion CT (PCT). These imaging modalities are used to determine the extent of injury, to provide information for the prediction of outcome, and to assess evidence of cerebral ischemia. In TBI, secondary brain damage mainly comprises ischemia and is present in more than 80% of fatal cases with traumatic brain injury (Graham et al., 1989; Bouma et al., 1991; Coles et al., 2004). In particular, while SPECT measures cerebral perfusion and MRS determines metabolism, PET is able to assess both perfusion and cerebral metabolism. This chapter will describe the application of these techniques in traumatic brain injury separately for the major groups of severity comprising the mild and moderate to severe group. The application in TBI and potential difficulties of each technique is described. The use of imaging techniques in children will be separately outlined.

Systemic glucose variability predicts cerebral metabolic distress and mortality after subarachnoid hemorrhage: a retrospective observational study

Introduction

Cerebral glucose metabolism and energy production are affected by serum glucose levels. Systemic glucose variability has been shown to be associated with poor outcome in critically ill patients. The objective of this study was to assess whether glucose variability is associated with cerebral metabolic distress and outcome after subarachnoid hemorrhage.

Methods

A total of 28 consecutive comatose patients with subarachnoid hemorrhage, who underwent cerebral microdialysis and intracranial pressure monitoring, were studied. Metabolic distress was defined as lactate/pyruvate ratio (LPR) >40. The relationship between daily glucose variability, the development of cerebral metabolic distress and hospital outcome was analyzed using a multivariable general linear model with a logistic link function for dichotomized outcomes.

Results

Daily serum glucose variability was expressed as the standard deviation (SD) of all serum glucose measurements. General linear models were used to relate this predictor variable to cerebral metabolic distress and mortality at hospital discharge. A total of 3,139 neuromonitoring hours and 181 days were analyzed. After adjustment for Glasgow Coma Scale (GCS) scores and brain glucose, SD was independently associated with higher risk of cerebral metabolic distress (adjusted odds ratio = 1.5 (1.1 to 2.1), P = 0.02). Increased variability was also independently associated with in hospital mortality after adjusting for age, Hunt Hess, daily GCS and symptomatic vasospasm (P = 0.03).

Conclusions

Increased systemic glucose variability is associated with cerebral metabolic distress and increased hospital mortality. Therapeutic approaches that reduce glucose variability may impact on brain metabolism and outcome after subarachnoid hemorrhage.

Brain tissue oxygen monitoring identifies cortical hypoxia and thalamic hyperoxia after experimental cardiac arrest in rats

BACKGROUND

Optimization of cerebral oxygenation after pediatric cardiac arrest (CA) may reduce neurological damage associated with the post-CA syndrome. We hypothesized that important alterations in regional partial pressure of brain tissue oxygen (PbO2) occur after resuscitation from CA and that clinically relevant interventions such as hyperoxia and blood pressure augmentation would influence PbO2.

METHODS

Cortical and thalamic PbO2 were monitored in immature rats subjected to asphyxial CA (9 or 12 min asphyxia) and sham-operated rats using oxygen sensors.

RESULTS

Thalamus and cortex showed similar baseline PbO2. Postresuscitation, there was early and sustained cortical hypoxia in an insult-duration dependent fashion. In contrast, thalamic PbO2 initially increased fourfold and afterwards returned to baseline values. PbO2 level was dependent on the fraction of inspired O2, and the response to oxygen was more pronounced after a 9 vs. 12 min CA. After a 12 min CA, PbO2 was modestly affected by blood pressure augmentation using epinephrine in the thalamus but not in the cortex.

CONCLUSION

After asphyxial pediatric CA, there is marked regional variability of cerebral oxygenation. Cortical hypoxia is pronounced and appears early, whereas thalamic hyperoxia is followed by normoxia. Compromised PbO2 in the cortex may represent a relevant and clinically measurable therapeutic target aimed at improving neurological outcome after pediatric CA.

Intracranial pressure monitoring, cerebral perfusion pressure estimation, and ICP/CPP-guided therapy: a standard of care or optional extra after brain injury?

Measurement of intracranial pressure (ICP) and mean arterial pressure (MAP) is used to derive cerebral perfusion pressure (CPP) and to guide targeted therapy of acute brain injury (ABI) during neurointensive care. Here we provide a narrative review of the evidence for ICP monitoring, CPP estimation, and ICP/CPP-guided therapy after ABI. Despite its widespread use, there is currently no class I evidence that ICP/CPP-guided therapy for any cerebral pathology improves outcomes; indeed some evidence suggests that it makes no difference, and some that it may worsen outcomes. Similarly, no class I evidence can currently advise the ideal CPP for any form of ABI. 'Optimal' CPP is likely patient-, time-, and pathology-specific. Further, CPP estimation requires correct referencing (at the level of the foramen of Monro as opposed to the level of the heart) for MAP measurement to avoid CPP over-estimation and adverse patient outcomes. Evidence is emerging for the role of other monitors of cerebral well-being that enable the clinician to employ an individualized multimodality monitoring approach in patients with ABI, and these are briefly reviewed. While acknowledging difficulties in conducting robust prospective randomized studies in this area, such high-quality evidence for the utility of ICP/CPP-directed therapy in ABI is urgently required. So, too, is the wider adoption of multimodality neuromonitoring to guide optimal management of ICP and CPP, and a greater understanding of the underlying pathophysiology of the different forms of ABI and what exactly the different monitoring tools used actually represent.

Beyond intracranial pressure: optimization of cerebral blood flow, oxygen, and substrate delivery after traumatic brain injury

Monitoring and management of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) is a standard of care after traumatic brain injury (TBI). However, the pathophysiology of so-called secondary brain injury, i.e., the cascade of potentially deleterious events that occur in the early phase following initial cerebral insult—after TBI, is complex, involving a subtle interplay between cerebral blood flow (CBF), oxygen delivery and utilization, and supply of main cerebral energy substrates (glucose) to the injured brain. Regulation of this interplay depends on the type of injury and may vary individually and over time. In this setting, patient management can be a challenging task, where standard ICP/CPP monitoring may become insufficient to prevent secondary brain injury. Growing clinical evidence demonstrates that so-called multimodal brain monitoring, including brain tissue oxygen (PbtO₂), cerebral microdialysis and transcranial Doppler among others, might help to optimize CBF and the delivery of oxygen/energy substrate at the bedside, thereby improving the management of secondary brain injury. Looking beyond ICP and CPP, and applying a multimodal therapeutic approach for the optimization of CBF, oxygen delivery, and brain energy supply may eventually improve overall care of patients with head injury. This review summarizes some of the important pathophysiological determinants of secondary cerebral damage after TBI and discusses novel approaches to optimize CBF and provide adequate oxygen and energy supply to the injured brain using multimodal brain monitoring.

Red Blood Cell Transfusion and Transfusion Alternatives in Traumatic Brain Injury

OPINION STATEMENT: Anemia develops in about 50% of patients hospitalized with traumatic brain injury (TBI) and is recognized as a cause of secondary brain injury. This review examines the effects of anemia and transfusion on TBI patients through a literature search to identify original research on anemia and transfusion in TBI, the effects of transfusion on brain physiology, and the role of erythropoietin or hemoglobin-based blood substitutes (HBBSs). However, the amount of high-quality, prospective data available to help make decisions about when TBI patients should be transfused is very small. Randomized transfusion trials have involved far too few TBI patients to reach definitive conclusions. Thus, it is hardly surprising that there is widespread practice variation. In our opinion, a hemoglobin transfusion threshold of 7 g/dL cannot yet be considered safe for TBI patients admitted to hospital, and in particular to the ICU, as it is for other critically ill patients. Red blood cell transfusions often have immediate, seemingly beneficial effects on cerebral physiology, but the magnitude of this effect may depend in part upon how long the cells have been stored before administration. In light of existing physiological data, we generally aim to keep hemoglobin concentrations greater than 9 g/dL during the first several days after TBI. In part, the decision is based on the patient's risk of or development of secondary ischemia or brain injury. An increasing number of centers use multimodal neurologic monitoring, which may help to individualize transfusion goals based on the degree of cerebral hypoxia or metabolic distress. When available, brain tissue oxygen tension values less than 15-20 mm Hg or a lactate:pyruvate ratio greater than 30-40 would influence us to use more aggressive hemoglobin correction (e.g., a transfusion threshold of 10 g/dL). Clinicians can attempt to reduce transfusion requirements by limiting phlebotomy, minimizing hemodilution, and providing appropriate prophylaxis against gastrointestinal hemorrhage. Administration of exogenous erythropoietin may have a small impact in further reducing the need for transfusion, but it also may increase complications, most notably deep venous thrombosis. Erythropoietin is currently of great interest as a potential neuroprotective agent, but until it is adequately evaluated in randomized controlled trials, it should not be used routinely for this purpose. HBBSs are also of interest, but existing preparations have not been shown to be beneficial-or even safe-in the context of TBI.

Red blood cell transfusion in the neurological ICU

Red blood cell transfusion (RBCT) is a common therapy used in the intensive care unit to treat anemia. However, due to deleterious side effects and questionable efficacy, the clinical benefit of RBCT in patients who are not actively bleeding is unclear. The results of randomized controlled trials suggest there is no benefit to a liberal transfusion practice in general critical care populations. Whether the results of these trials are applicable to brain injured patients is unknown, as patients with primary neurological injury were excluded. This article reviews the efficacy and complications of RBCT, as well as the relationship between RBCT and its outcome in both the general intensive care unit and neurologically critically ill populations.

Neuromonitoring for Traumatic Brain Injury in Neurosurgical Intensive Care

The primary aim of neuromonitoring in patients with traumatic brain injury is early detection of secondary brain insults so that timely interventions can be instituted to prevent or treat secondary brain injury. Intracranial pressure monitoring has been a stalwart in neuromonitoring and is still very much the main parameter to guide therapy in brain injured patients in many centres. Cerebral oxygenation is also established as an important parameter for monitoring: global cerebral oxygenation is reliably measured using jugular venous oxygen saturation while brain tissue oxygen tension measurement allows focal brain oxygenation to be monitored. Near-infrared spectroscopy allows a non-invasive option for monitoring of regional cerebral oxygenation. Cerebral microdialysis makes focal measurements of markers of cellular metabolism and cellular injury and death possible, and it is in transition from being a research tool to being an important clinical tool in neuromonitoring. Multimodal monitoring allows different parameters of brain physiology and function to be monitored and can improve identification and prediction of secondary cerebral insults. Multimodal monitoring can potentially improve outcomes in patients with traumatic brain injury by promoting customised treatment strategies for individual patients in place of the commonplace practice of strict adherence to achieving the same standard physiological targets for every patient.

Hyperglycemia in aneurysmal subarachnoid hemorrhage: a potentially modifiable risk factor for poor outcome

Hyperglycemia after aneurysmal subarachnoid hemorrhage (aSAH) occurs frequently and is associated with delayed cerebral ischemia (DCI) and poor clinical outcome. In this review, we highlight the mechanisms that cause hyperglycemia after aSAH, and we discuss how hyperglycemia may contribute to poor clinical outcome in these patients. As hyperglycemia is potentially modifiable with intensive insulin therapy (IIT), we systematically reviewed the literature on IIT in aSAH patients. In these patients, IIT seems to be difficult to achieve in terms of lowering blood glucose levels substantially without an increased risk of (serious) hypoglycemia. Therefore, before initiating a large-scale randomized trial to investigate the clinical benefit of IIT, phase II studies, possibly with the help of cerebral blood glucose monitoring by microdialysis, will first have to improve this therapy in terms of both safety and adequacy.

Early prognosis in traumatic brain injury: from prophecies to predictions

Traumatic brain injury (TBI) is a heterogeneous condition that encompasses a broad spectrum of disorders. Outcome can be highly variable, particularly in more severely injured patients. Despite the association of many variables with outcome, prognostic predictions are notoriously difficult to make. Multivariable analysis has identified age, clinical severity, CT abnormalities, systemic insults (hypoxia and hypotension), and laboratory variables as relevant factors to include in models to predict outcome in individual patients. Advances in statistical modelling and the availability of large datasets have facilitated the development of prognostic models that have greater performance and generalisability. Two prediction models are currently available, both of which have been developed on large datasets with state-of-the-art methods, and offer new opportunities. We see great potential for their use in clinical practice, research, and policy making, as well as for assessment of the quality of health-care delivery. Continued development, refinement, and validation is advocated, together with assessment of the clinical impact of prediction models, including treatment response.

Low hemoglobin is associated with poor functional outcome after non-traumatic, supratentorial intracerebral hemorrhage

Introduction

The impact of anemia on functional outcome and mortality in patients suffering from non-traumatic intracerebral hemorrhage (ICH) has not been investigated. Here, we assessed the relationship between hemoglobin (HB) levels and clinical outcome after ICH.

Methods

One hundred and ninety six patients suffering from supratentorial, non-traumatic ICH were extracted from our local stroke database (June 2004 to June 2006). Clinical and radiologic computed tomography data, HB levels on admission, mean HB values and nadir during hospital stay were recorded. Outcome was assessed at discharge and 3 months using the modified Rankin score (mRS).

Results

Forty six (23.5%) patients achieved a favorable functional outcome (mRS ≤ 3) and 150 (76.5%) had poor outcome (mRS 4 - 6) at discharge. Patients with poor functional outcome had a lower mean HB (12.3 versus 13.7 g/dl, P < 0.001) and nadir HB (11.5 versus 13.0 g/dl, P < 0.001). Ten patients (5.1%) received red blood cell (RBC) transfusions. In a multivariate logistic regression model, the mean HB was an independent predictor for poor functional outcome at three months (odds ratio (OR) 0.73, 95% confidence interval (CI) 0.58-0.92, P = 0.007), along with National Institute of Health Stroke Scale (NIHSS) at admission (OR 1.17, 95% CI 1.11 - 1.24, P < 0.001), and age (OR 1.08, 95% CI 1.04 - 1.12, P < 0.001).

Conclusions

We report an association between low HB and poor outcome in patients with non-traumatic, supratentorial ICH. While a causal relationship could not be proven, previous experimental studies and studies in brain injured patients provide evidence for detrimental effects of anemia on brain metabolism. However, the potential risk of anemia must be balanced against the risk of harm from red blood cell infusion.

Intracerebral microdialysis in children

INTRODUCTION

Cerebral microdialysis is a relatively new, minimally invasive technique that permits sampling and analyzing the chemical constituents of the extracellular fluid. Although mainly used as a research tool, it is also used in the neurointensive care, in combination with other monitoring methods, in patients with severe traumatic brain injury and subarachnoid hemorrhage. Its main clinical utility is the identification of markers of ischemia and cell damage with the ultimate goal of preventing any secondary insults to the brain by instituting early appropriate treatment measures. With few exceptions, all the available data on intracerebral microdialysis in humans comes from studies performed in adults.

OBJECTIVE

The purpose of this report is to provide a brief review of the intracerebral microdialysis studies performed in children.

CONCLUSION

Differences in trends of concentrations of structural and excitatory amino acids have been identified in children, in comparison to those observed in adults, the significance of which remains unknown at present.

Microdialysis: is it ready for prime time?

PURPOSE OF REVIEW

This review highlights recent advances in cerebral microdialysis for investigational and clinical neurochemical monitoring in patients with critical neurological conditions.

RECENT FINDINGS

Use of microdialysis with other methods, including PET, electrophysiological monitoring and brain tissue oximetry in traumatic brain injury, subarachnoid hemorrhage with vasospasm, and infarction with refractory increased intracranial pressure have been reported. Potentially adverse neurochemical effects of nonconvulsive status epilepticus and cortical slow depolarization waves, both of which are increasingly recognized in traumatic brain injury and stroke patients, have been reported. The explosive growth in the use of cerebral oximetry with targeted management of brain tissue oxygen levels is leading to greater understanding of derangements of cerebral bioenergetics in the critically ill brain, but there remain unresolved basic issues. Understanding of the analytes that are measurable at the bedside - glucose, lactate, pyruvate, glutamate and glycerol - continues to evolve with glucose, lactate, pyruvate and the lactate-pyruvate ratio taking center stage. Analytes including inflammatory biomarkers such as cytokines and metabolites of nitric oxide are presently investigational, but hold promise for future application in advancing our understanding of basic pathophysiology, therapeutic target selection and prognostication. Growing consensus on indications for use of clinical microdialysis and advances in commercially available equipment continue to make microdialysis increasingly 'ready for prime time.'

SUMMARY

Cerebral microdialysis is an established tool for neurochemical research in the ICU. This technique cannot be fruitfully used in isolation, but when combined with other monitoring methods provides unique insights into the biochemical and physiological derangements in the injured brain.

Urea clearance: a new method to register local changes in blood flow in rat skeletal muscle based on microdialysis

SUMMARY

Increasing evidence suggests that local blood flow should be monitored during microdialysis (MD) as the recovery of analytes is affected by local blood flow. At present ethanol clearance is the standard technique for this purpose, but it is not functional at very low perfusion velocities. Here, we introduce a technique for MD whereby local tissue blood flow is recorded by the use of urea clearance (changes inflow/outflow concentration), in conjunction with measurements of tissue metabolism (glucose, lactate and puruvate). MD probes were inserted into the gracilis muscle of 15 rats and perfused with a medium containing urea (20 mmol l(-1)). Changes in muscle blood flow were made by addition of noradrenaline (5 microg ml(-1)) to the perfusion medium at two perfusion velocities (0.6 and 0.4 microl min(-1)). The clearance of urea from the perfusion medium was then calculated and examined in relation to the dose of noradrenaline and to the coexisting changes in extracellular metabolites. The results showed reproducible and dose-dependent changes in blood flow that were induced by noradrenaline. These were characterized by dose-dependent changes in the urea clearance as well as blood-flow-specific changes in the MD metabolic markers (reduction in glucose and increase in lactate). The sensitivity for blood flow changes as assessed by urea clearance (MD) was increased at 0.4 compared with the 0.6 microl min(-1) perfusion speed. The results indicate that inclusion of urea to the perfusion medium may be used to monitor changes in skeletal muscle blood flow at low perfusion velocities and in parallel assess metabolic variables with a high recovery (>90%).

Monitoring of brain interstitial total tau and beta amyloid proteins by microdialysis in patients with traumatic brain injury

OBJECT

Damage to axons contributes to postinjury disabilities and is commonly observed following traumatic brain injury (TBI). Traumatic brain injury is an important environmental risk factor for the development of Alzheimer disease (AD). In the present feasibility study, the aim was to use intracerebral microdialysis catheters with a high molecular cutoff membrane (100 kD) to harvest interstitial total tau (T-tau) and amyloid beta 1-42 (Abeta42) proteins, which are important biomarkers for axonal injury and for AD, following moderate-to-severe TBI.

METHODS

Eight patients (5 men and 3 women) were included in the study; 5 of the patients had a focal/mixed TBI and 3 had a diffuse axonal injury (DAI). Following the bedside analysis of the routinely measured energy metabolic markers (that is, glucose, lactate/pyruvate ratio, glycerol, and glutamate), the remaining dialysate was pooled and two 12-hour samples per day were used to analyze T-tau and Abeta42 by enzyme-linked immunosorbent assay from Day 1 up to 8 days postinjury.

RESULTS

The results show high levels of interstitial T-tau and Abeta42 postinjury. Patients with a predominantly focal lesion had higher interstitial T-tau levels than in the DAI group from Days 1 to 3 postinjury (p < 0.05). In contrast, patients with DAI had consistently higher Abeta42 levels when compared with patients with focal injury.

CONCLUSIONS

These results suggest that monitoring of interstitial T-tau and Abeta42 by using microdialysis may be an important tool when evaluating the presence and role of axonal injury following TBI.

Anemia and red blood cell transfusion in neurocritical care

INTRODUCTION

Anemia is one of the most common medical complications to be encountered in critically ill patients. Based on the results of clinical trials, transfusion practices across the world have generally become more restrictive. However, because reduced oxygen delivery contributes to 'secondary' cerebral injury, anemia may not be as well tolerated among neurocritical care patients.

METHODS

The first portion of this paper is a narrative review of the physiologic implications of anemia, hemodilution, and transfusion in the setting of brain-injury and stroke. The second portion is a systematic review to identify studies assessing the association between anemia or the use of red blood cell transfusions and relevant clinical outcomes in various neurocritical care populations.

RESULTS

There have been no randomized controlled trials that have adequately assessed optimal transfusion thresholds specifically among brain-injured patients. The importance of ischemia and the implications of anemia are not necessarily the same for all neurocritical care conditions. Nevertheless, there exists an extensive body of experimental work, as well as human observational and physiologic studies, which have advanced knowledge in this area and provide some guidance to clinicians. Lower hemoglobin concentrations are consistently associated with worse physiologic parameters and clinical outcomes; however, this relationship may not be altered by more aggressive use of red blood cell transfusions.

CONCLUSIONS

Although hemoglobin concentrations as low as 7 g/dl are well tolerated in most critical care patients, such a severe degree of anemia could be harmful in brain-injured patients. Randomized controlled trials of different transfusion thresholds, specifically in neurocritical care settings, are required. The impact of the duration of blood storage on the neurologic implications of transfusion also requires further investigation.

Intensive care unit robotic telepresence facilitates rapid physician response to unstable patients and decreased cost in neurointensive care

BACKGROUND

The timely assessment and treatment of ICU patients is important for neurosurgeons and neurointensivists. We hypothesized that the use of RTP can improve physician rapid response to unstable ICU patients.

METHODS

This is a prospective study using a before-after, cohort-control design to test the effectiveness of RTP. Physicians used RTP to make rounds in the ICU in response to nursing pages. Data concerning several aspects of the RTP interaction including the latency of the response, the problem being treated, the intervention that was ordered, and the type of information gathered using the RTP were documented. The effect of RTP on ICU length of stay and cost was assessed.

RESULTS

The use of RTP was associated with a reduction in latency of attending physician face-to-face response for routine and urgent pages compared to conventional care (RTP: 9.2 +/- 9.3 minutes vs conventional: 218 +/- 186 minutes). The response latencies to brain ischemia (7.8 +/- 2.8 vs 152 +/- 85 minutes) and elevated ICP (11 +/- 14 vs 108 +/- 55 minutes) were reduced (P < .001), as was the LOS for patients with SAH (2 days) and brain trauma (1 day). There was an increase in ICU occupancy by 11% compared with the prerobot era, and there was an ICU cost savings of $1.1 million attributable to the use of RTP.

CONCLUSION

The use of RTP enabled rapid face-to-face attending physician response to ICU patients and resulted in decreased ICU cost and LOS.