Effects of iso- and hypervolemic hemodilution on regional cerebral blood flow and oxygen delivery for patients with vasospasm after aneurysmal subarachnoid hemorrhage

Hematocrit drift and outcomes in surgical patients with aneurysmal subarachnoid hemorrhage

BACKGROUND

There is a paucity of conclusive evidence regarding the impact of downward drift in hematocrit levels among patients who have undergone surgical clipping for aneurysmal subarachnoid hemorrhage (aSAH). This study endeavors to explore the potential association between hematocrit drift and mortality in this specific patient population.

METHODS

A cohort study was conducted, encompassing adult patients diagnosed with aSAH at a university hospital. The primary endpoint was follow-up mortality. Propensity score matching was employed to align patients based on their baseline characteristics. Discrimination capacity across various models was assessed and compared using net reclassification improvement (NRI).

RESULTS

Among the 671 patients with aSAH in the study period, 118 patients (17.6%) experienced an in-hospital hematocrit drift of more than 25%. Following adjustment with multivariate regression analysis, patients with elevated hematocrit drift demonstrated significantly increased odds of mortality (aOR: 2.12, 95% CI: 1.14 to 3.97; P = 0.019). Matching analysis yielded similar results (aOR: 2.07, 95% CI: 1.05 to 4.10; P = 0.036). The inclusion of hematocrit drift significantly improved the NRI (P < 0.0001) for mortality prediction. When in-hospital hematocrit drift was served as a continuous variable, each 10% increase in hematocrit drift corresponded to an adjusted odds ratio of 1.31 (95% CI 1.08-1.61; P = 0.008) for mortality.

CONCLUSIONS

In conclusion, the findings from this comprehensive cohort study indicate that a downward hematocrit drift exceeding 25% independently predicts mortality in surgical patients with aSAH. These findings underscore the significance of monitoring hematocrit and managing anemia in this patient population.

Anemia and Optimal Transfusion Thresholds in Brain-Injured Patients: A Narrative Review of the Literature

Anemia is a highly prevalent condition that may compromise oxygen delivery to vital organs, especially among the critically ill. Although current evidence supports the adoption of a restrictive transfusion strategy and threshold among the nonbleeding critically ill patient, it remains unclear whether this practice should apply to the brain-injured patient, given the predisposition to cerebral ischemia in this patient population, in which even nonprofound anemia may exert a detrimental effect on clinical outcomes. The purpose of this review is to provide an overview of the pathophysiological changes related to impaired cerebral oxygenation in the brain-injured patient and to present the available evidence on the effect of anemia and varying transfusion thresholds on the clinical outcomes of patients with acute brain injury.

Diagnosis and management of subarachnoid haemorrhage

Aneurysmal subarachnoid haemorrhage (aSAH) presents a challenge to clinicians because of its multisystem effects. Advancements in computed tomography (CT), endovascular treatments, and neurocritical care have contributed to declining mortality rates. The critical care of aSAH prioritises cerebral perfusion, early aneurysm securement, and the prevention of secondary brain injury and systemic complications. Early interventions to mitigate cardiopulmonary complications, dyselectrolytemia and treatment of culprit aneurysm require a multidisciplinary approach. Standardised neurological assessments, transcranial doppler (TCD), and advanced imaging, along with hypertensive and invasive therapies, are vital in reducing delayed cerebral ischemia and poor outcomes. Health care disparities, particularly in the resource allocation for SAH treatment, affect outcomes significantly, with telemedicine and novel technologies proposed to address this health inequalities. This article underscores the necessity for comprehensive multidisciplinary care and the urgent need for large-scale studies to validate standardised treatment protocols for improved SAH outcomes.

Cerebral Microdialysis Monitoring of Energy Metabolism: Relation to Cerebral Blood Flow and Oxygen Delivery in Aneurysmal Subarachnoid Hemorrhage

INTRODUCTION

In this study, we investigated the roles of cerebral blood flow (CBF) and cerebral oxygen delivery (CDO 2 ) in relation to cerebral energy metabolism after aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

Fifty-seven adult aSAH patients treated on the neurointensive care unit at Uppsala, Sweden between 2012 and 2020, with at least 1 xenon-enhanced computed tomography (Xe-CT) scan in the first 14 days after ictus and concurrent microdialysis (MD) monitoring, were included in this retrospective study. CBF was measured globally and focally (around the MD catheter) with Xe-CT, and CDO 2 calculated. Cerebral energy metabolites were measured using MD.

RESULTS

Focal ischemia (CBF <20 mL/100 g/min around the MD catheter was associated with lower median [interquartile range]) MD-glucose (1.2 [0.7 to 2.2] mM vs. 2.3 [1.3 to 3.5] mM; P =0.05) and higher MD-lactate-pyruvate (LPR) ratio (34 [29 to 66] vs. 25 [21 to 32]; P =0.02). A compensated/normal MD pattern (MD-LPR <25) was observed in the majority of patients (22/23, 96%) without focal ischemia, whereas 4 of 11 (36%) patients with a MD pattern of poor substrate supply (MD-LPR >25, MD-pyruvate <120 µM) had focal ischemia as did 5 of 20 (25%) patients with a pattern of mitochondrial dysfunction (MD-LPR >25, MD-pyruvate >120 µM) ( P =0.04). Global CBF and CDO 2 , and focal CDO 2 , were not associated with the MD variables.

CONCLUSIONS

While MD is a feasible tool to study cerebral energy metabolism, its validity is limited to a focal area around the MD catheter. Cerebral energy disturbances were more related to low CBF than to low CDO 2 . Considering the high rate of mitochondrial dysfunction, treatments that increase CBF but not CDO 2 , such as hemodilution, may still benefit glucose delivery to drive anaerobic metabolism.

Recent insights into mechanisms of hypoxia-induced vasodilatation in the human brain

The cerebral vasculature manages oxygen delivery by adjusting arterial blood in-flow in the face of reductions in oxygen availability. Hypoxic cerebral vasodilatation, and the associated hypoxic cerebral blood flow reactivity, involve many vascular, erythrocytic and cerebral tissue mechanisms that mediate elevations in cerebral blood flow via micro- and macrovascular dilatation. This contemporary review focuses on in vivo human work - with reference to seminal preclinical work where necessary - on hypoxic cerebrovascular reactivity, particularly where recent advancements have been made. We provide updates with the following information: in humans, hypoxic cerebral vasodilatation is partially mediated via a - likely non-obligatory - combination of: (1) nitric oxide synthases, (2) deoxygenation-coupled S-nitrosothiols, (3) potassium channel-related vascular smooth muscle hyperpolarization, and (4) prostaglandin mechanisms with some contribution from an interrelationship with reactive oxygen species. And finally, we discuss the fact that, due to the engagement of deoxyhaemoglobin-related mechanisms, reductions in O2 content via haemoglobin per se seem to account for ∼50% of that seen with hypoxic cerebral vasodilatation during hypoxaemia. We further highlight the issue that methodological impediments challenge the complete elucidation of hypoxic cerebral reactivity mechanisms in vivo in healthy humans. Future research is needed to confirm recent advancements and to reconcile human and animal findings. Further investigations are also required to extend these findings to address questions of sex-, heredity-, age-, and disease-related differences. The final step is to then ultimately translate understanding of these mechanisms into actionable, targetable pathways for the prevention and treatment of cerebral vascular dysfunction and cerebral hypoxic brain injury.

Anemia and Red Blood Cell Transfusion in Aneurysmal Subarachnoid Hemorrhage

Anemia is very common in aneurysmal subarachnoid hemorrhage (aSAH), with approximately half of the aSAH patient population developing moderate anemia during their hospital stay. The available evidence (both physiologic and clinical) generally supports an association of anemia with unfavorable outcomes. Although aSAH shares a number of common mechanisms of secondary insult with other forms of acute brain injury, aSAH also has specific features that make it unique: an early phase (in which early brain injury predominates) and a delayed phase (in which delayed cerebral ischemia and vasospasm predominate). The effects of both anemia and transfusion are potentially variable between these phases, which may have unique considerations and possibly different risk-benefit profiles. Data on transfusion in this population are almost exclusively limited to observational studies, which suffer from significant heterogeneity and risk of bias. Overall, the results are conflicting, with the balance of the studies suggesting that transfusion is associated with unfavorable outcomes. The transfusion targets that are well established in other critically ill populations should not be automatically applied to patients with aSAH because of the unique disease characteristics of this population and the limited representation of aSAH in the clinical trials that established these targets. There are two upcoming clinical trials evaluating transfusion in aSAH that should help clarify specific transfusion targets. Until then, it is reasonable to base transfusion decisions on the current guidelines and use an individualized approach incorporating physiologic and clinical data when available.

Hemodynamic Management in the Prevention and Treatment of Delayed Cerebral Ischemia After Aneurysmal Subarachnoid Hemorrhage

One of the most serious complications after subarachnoid hemorrhage (SAH) is delayed cerebral ischemia, the cause of which is multifactorial. Delayed cerebral ischemia considerably worsens neurological outcome and increases the risk of death. The targets of hemodynamic management of SAH have widely changed over the past 30 years. Hypovolemia and hypotension were favored prior to the era of early aneurysmal surgery but were subsequently replaced by the use of hypervolemia and hypertension. More recently, the concept of goal-directed therapy targeting euvolemia, with or without hypertension, is gaining preference. Despite the evolving concepts and the vast literature, fundamental questions related to hemodynamic optimization and its effects on cerebral perfusion and patient outcomes remain unanswered. In this review, we explain the rationale underlying the approaches to hemodynamic management and provide guidance on contemporary strategies related to fluid administration and blood pressure and cardiac output manipulation in the management of SAH.

Lateral position does not cause an interhemicerebral difference of cerebral hemodynamic in healthy adult volunteers

Cerebral perfusion is maintained at a consistent value irrespective of changes in systemic blood pressure or disease-induced changes in general physical condition. This regulatory mechanism is effective despite postural changes, working even during changes in posture, such as those from sitting to standing or from the head-down to the head-up position. However, no study has addressed changes in perfusion separately in the left and right cerebral hemispheres, and there has been no specific investigation of the effect of the lateral decubitus position on perfusion in each hemisphere. Surgery, particularly respiratory surgery, is often performed with the patient in the lateral decubitus position, and since intraoperative anesthesia may also have an effect, it is important to ascertain the effect of the lateral decubitus position on perfusion in the left and right cerebral hemispheres in the absence of anesthesia. The effects of the lateral decubitus position on heart rate, blood pressure, and hemodynamic in the left and right cerebral hemispheres assessed by regional saturation of oxygen measured by near-infrared spectroscopy were investigated in healthy adult volunteers. Although the lateral decubitus position causes systemic circulatory changes, it may not cause any difference in hemodynamic between the left and right cerebral hemispheres.

Fine tuning of neurointensive care in aneurysmal subarachnoid hemorrhage: From one-size-fits-all towards individualized care

Aneurysmal subarachnoid hemorrhage (aSAH) is a severe type of acute brain injury with high mortality and burden of neurological sequelae. General management aims at early aneurysm occlusion to prevent re-bleeding, cerebrospinal fluid drainage in case of increased intracranial pressure and/or acute hydrocephalus, and cerebral blood flow augmentation in case of delayed ischemic neurological deficits. In addition, the brain is vulnerable to physiological insults in the acute phase and neurointensive care (NIC) is important to optimize the cerebral physiology to avoid secondary brain injury. NIC has led to significantly better neurological recovery following aSAH, but there is still great room for further improvements. First, current aSAH NIC management protocols are to some extent extrapolated from those in traumatic brain injury, notwithstanding important disease-specific differences. Second, the same NIC management protocols are applied to all aSAH patients, despite great patient heterogeneity. Third, the main variables of interest, intracranial pressure and cerebral perfusion pressure, may be too superficial to fully detect and treat several important pathomechanisms. Fourth, there is a lack of understanding not only regarding physiological, but also cellular and molecular pathomechanisms and there is a need to better monitor and treat these processes. This narrative review aims to discuss current state-of-the-art NIC of aSAH, knowledge gaps in the field, and future directions towards a more individualized care in the future.

Cerebral O2 and CO2 transport in isovolumic haemodilution: Compensation of cerebral delivery of O2 and maintenance of cerebrovascular reactivity to CO2

This study investigated the influence of acute reductions in arterial O₂ content (CaO₂) via isovolumic haemodilution on global cerebral blood flow (gCBF) and cerebrovascular CO₂ reactivity (CVR) in 11 healthy males (age; 28 ± 7 years: body mass index; 23 ± 2 kg/m²). Radial artery and internal jugular vein catheters provided measurement of blood pressure and gases, quantification of cerebral metabolism, cerebral CO₂ washout, and trans-cerebral nitrite exchange (ozone based chemiluminescence). Prior to and following haemodilution, the partial pressure of arterial CO₂ (PaCO₂) was elevated with dynamic end-tidal forcing while gCBF was measured with duplex ultrasound. CVR was determined as the slope of the gCBF response and PaCO₂. Replacement of ∼20% of blood volume with an equal volume of 5% human serum albumin (Alburex® 5%) reduced haemoglobin (13.8 ± 0.8 vs. 11.3 ± 0.6 g/dL; P < 0.001) and CaO₂ (18.9 ± 1.0 vs 15.0 ± 0.8 mL/dL P < 0.001), elevated gCBF (+18 ± 11%; P = 0.002), preserved cerebral oxygen delivery (P = 0.49), and elevated CO₂ washout (+11%; P = 0.01). The net cerebral uptake of nitrite (11.6 ± 14.0 nmol/min; P = 0.027) at baseline was abolished following haemodilution (-3.6 ± 17.9 nmol/min; P = 0.54), perhaps underpinning the conservation of CVR (61.7 ± 19.0 vs. 69.0 ± 19.2 mL/min/mmHg; P = 0.23). These findings demonstrate that the cerebrovascular responses to acute anaemia in healthy humans are sufficient to support the maintenance of CVR.

Associations Between Transcranial Doppler Vasospasm and Clinical Outcomes After Aneurysmal Subarachnoid Hemorrhage: A Retrospective Observational Study

OBJECTIVE

The objective is to examine the relationship between transcranial Doppler cerebral vasospasm (TCD-vasospasm), and clinical outcomes in aneurysmal subarachnoid hemorrhage (aSAH).

METHODS

In a retrospective cohort study, using univariate and multivariate analysis, we examined the association between TCD-vasospasm (defined as Lindegaard ratio >3) and patient's ability to ambulate without assistance, the need for tracheostomy and gastrostomy tube placement, and the likelihood of being discharged home from the hospital.

RESULTS

We studied 346 patients with aSAH; median age 55 years (Interquartile range IQR 46,64), median Hunt and Hess 3 [IQR 1-5]. Overall, 68.6% (n=238) had TCD-vasospasm, and 28% (n=97) had delayed cerebral ischemia. At hospital discharge, 54.3% (n=188) were able to walk without assistance, 5.8% (n=20) had received a tracheostomy, and 12% (n=42) had received a gastrostomy tube. Fifty-three percent (n=183) were discharged directly from the hospital to their home. TCD-vasospasm was not associated with ambulation without assistance at discharge (adjusted odds ratio, aOR 0.54, 95% 0.19,1.45), tracheostomy placement (aOR 2.04, 95% 0.23,18.43), gastrostomy tube placement (aOR 0.95, 95% CI 0.28,3.26), discharge to home (aOR 0.36, 95% CI 0.11,1.23).

CONCLUSION

This single-center retrospective study finds that TCD-vasospasm is not associated with clinical outcomes such as ambulation without assistance, discharge to home from the hospital, tracheostomy, and gastrostomy feeding tube placement. Routine screening for cerebral vasospasm and its impact on vasospasm diagnostic and therapeutic interventions and their associations with improved clinical outcomes warrant an evaluation in large, prospective, case-controlled, multi-center studies.

Hemodynamic Monitoring in Patients With Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis

Aneurysmal subarachnoid hemorrhage (aSAH) often causes cardiopulmonary dysfunction. Therapeutic strategies can be guided by standard (invasive arterial/central venous pressure measurements, fluid balance assessment), and/or advanced (pulse index continuous cardiac output, pulse dye densitometry, pulmonary artery catheterization) hemodynamic monitoring. We conducted a systematic review and meta-analysis of the literature to determine whether standard compared with advanced hemodynamic monitoring can improve patient management and clinical outcomes after aSAH. A literature search was performed for articles published between January 1, 2000 and January 1, 2019. Studies involving aSAH patients admitted to the intensive care unit and subjected to any type of hemodynamic monitoring were included. A total of 14 studies were selected for the qualitative synthesis and 3 randomized controlled trials, comparing standard versus advanced hemodynamic monitoring, for meta-analysis. The incidence of delayed cerebral ischemia was lower in the advanced compared with standard hemodynamic monitoring group (relative risk [RR]=0.71, 95% confidence interval [CI]=0.52-0.99; P=0.044), but there were no differences in neurological outcome (RR=0.83, 95% CI=0.64-1.06; P=0.14), pulmonary edema onset (RR=0.44, 95% CI=0.05-3.92; P=0.46), or fluid intake (mean difference=-169 mL; 95% CI=-1463 to 1126 mL; P=0.8) between the 2 groups. In summary, this systematic review and meta-analysis found only low-quality evidence to support the use of advanced hemodynamic monitoring in selected aSAH patients. Because of the small number and low quality of studies available for inclusion in the review, further studies are required to investigate the impact of standard and advanced hemodynamic monitoring-guided management on aSAH outcomes.

Aneurysmal Subarachnoid Hemorrhage: Review of the Pathophysiology and Management Strategies

PURPOSE OF REVIEW

Aneurysmal subarachnoid hemorrhage remains a devastating disease process despite medical advances made over the past 3 decades. Much of the focus was on prevention and treatment of vasospasm to reduce delayed cerebral ischemia and improve outcome. In recent years, there has been a shift of focus onto early brain injury as the precursor to delayed cerebral ischemia. This review will focus on the most recent data surrounding the pathophysiology of aneurysmal subarachnoid hemorrhage and current management strategies.

RECENT FINDINGS

There is a paucity of successful trials in the management of subarachnoid hemorrhage likely related to the targeting of vasospasm. Pathophysiological changes occurring at the time of aneurysmal rupture lead to early brain injury including cerebral edema, inflammation, and spreading depolarization. These events result in microvascular collapse, vasospasm, and ultimately delayed cerebral ischemia. Management of aneurysmal subarachnoid hemorrhage has remained the same over the past few decades. No recent trials have resulted in new treatments. However, our understanding of the pathophysiology is rapidly expanding and will advise future therapeutic targets.

Intracranial Vascular Procedures

Anesthesia for intracranial vascular procedures is complex because it requires a balance of several competing interests and potentially can result in significant morbidity and mortality. Frequently, periods of ischemia, where perfusion must be maintained, are combined with situations that are high risk for hemorrhage. This review discusses the basic surgical approach to several common pathologies (intracranial aneurysms, arteriovenous malformations, and moyamoya disease) along with the goals for anesthetic management and specific high-yield recommendations.

The Updated Role of the Blood Brain Barrier in Subarachnoid Hemorrhage: From Basic and Clinical Studies

Subarachnoid hemorrhage (SAH) is a type of hemorrhagic stroke associated with high mortality and morbidity. The blood-brain-barrier (BBB) is a structure consisting primarily of cerebral microvascular endothelial cells, end feet of astrocytes, extracellular matrix, and pericytes. Post-SAH pathophysiology included early brain injury and delayed cerebral ischemia. BBB disruption was a critical mechanism of early brain injury and was associated with other pathophysiological events. These pathophysiological events may propel the development of secondary brain injury, known as delayed cerebral ischemia. Imaging advancements to measure BBB after SAH primarily focused on exploring innovative methods to predict clinical outcome, delayed cerebral ischemia, and delayed infarction related to delayed cerebral ischemia in acute periods. These predictions are based on detecting abnormal changes in BBB permeability. The parameters of BBB permeability are described by changes in computed tomography (CT) perfusion and magnetic resonance imaging (MRI). K_ep seems to be a stable and sensitive indicator in CT perfusion, whereas K^trans is a reliable parameter for dynamic contrast-enhanced MRI. Future prediction models that utilize both the volume of BBB disruption and stable parameters of BBB may be a promising direction to develop practical clinical tools. These tools could provide greater accuracy in predicting clinical outcome and risk of deterioration. Therapeutic interventional exploration targeting BBB disruption is also promising, considering the extended duration of post-SAH BBB disruption.

Transcranial Doppler Sonography Defined Vasospasm, Ischemic Brain Lesions, and Delayed Ischemic Neurological Deficit in Younger and Elderly Patients after Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

Vasospasm, delayed ischemic neurologic deficit (DIND), and ischemic brain lesions after acute subarachnoid hemorrhage (SAH) are associated with increased morbidity and mortality. The purpose of this study was to analyze age cutoffs for vasospasm, DIND, and ischemic brain lesions after SAH.

METHODS

This study included 292 aneurysmal SAH patients from January 2005 to December 2015. Patients' data were extracted from a prospective database with measurements of transcranial Doppler sonography. Any vasospasm was defined as a maximum mean flow velocity (MMFV) >120 cm/sec. Severe vasospasms were defined as at least 2 measurements of MMFVs >200 cm/sec or an increase of MMFV >50 cm/sec/24 hours over 2 consecutive days or a new neurologic deficit. All MMFVs >120 cm/sec in absence of severe vasospasm criteria were defined as mild vasospasm. Age-related cutoff values were calculated using receiver operating curve analysis.

RESULTS

Any vasospasms occurred in 142 patients and thereof mild vasospasm in 86/142 (60.6%) patients and severe vasospasm in 56/142 patients (39.4%). Significantly higher incidences of any vasospasm (P = 0.005), severe vasospasm (P = 0.003), DIND (P = 0.031), and ischemic brain lesions (P = 0.04) were observed in patients aged <50 years. According to receiver operating curve analysis, the optimal age cutoff was 50 years for the presence of overall vasospasms, severe vasospasms, DIND, and ischemic brain lesions and 65 years for mild vasospasms.

CONCLUSIONS

Higher incidences of any vasospasms, severe vasospasms, DIND, and ischemic brain lesions were observed in younger SAH patients.

Clinical and experimental aspects of aneurysmal subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) continues to be associated with significant morbidity and mortality despite advances in care and aneurysm treatment strategies. Cerebral vasospasm continues to be a major source of clinical worsening in patients. We intended to review the clinical and experimental aspects of aSAH and identify strategies that are being evaluated for the treatment of vasospasm. A literature review on aSAH and cerebral vasospasm was performed. Available treatments for aSAH continue to expand as research continues to identify new therapeutic targets. Oral nimodipine is the primary medication used in practice given its neuroprotective properties. Transluminal balloon angioplasty is widely utilized in patients with symptomatic vasospasm and ischemia. Prophylactic "triple-H" therapy, clazosentan, and intraarterial papaverine have fallen out of practice. Trials have not shown strong evidence supporting magnesium or statins. Other calcium channel blockers, milrinone, tirilazad, fasudil, cilostazol, albumin, eicosapentaenoic acid, erythropoietin, corticosteroids, minocycline, deferoxamine, intrathecal thrombolytics, need to be further investigated. Many of the current experimental drugs may have significant roles in the treatment algorithm, and further clinical trials are needed. There is growing evidence supporting that early brain injury in aSAH may lead to significant morbidity and mortality, and this needs to be explored further.

The Extracranial Consequences of Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is managed across the full spectrum of healthcare, from clinical diagnosis to management of the hemorrhage and associated complications. Knowledge of the pathogenesis and pathophysiology of SAH is widely known; however, a full understanding of the underlying molecular, cellular, and circulatory dynamics has still to be achieved. Intracranial complications including delayed ischemic neurologic deficit (vasospasm), rebleed, and hydrocephalus form the targets for initial management. However, the extracranial consequences including hypertension, hyponatremia, and cardiopulmonary abnormalities can frequently arise during the management phase and have shown to directly affect clinical outcome. This review will provide an update on the pathophysiology of SAH, including the intra- and extracranial consequences, with a particular focus on the extracranial consequences of SAH.

METHODS

We review the literature and provide a comprehensive update on the extracranial consequences of SAH that we hope will help the management of these cohort of patients.

RESULTS

In addition to the pathophysiology of SAH, the following complications were examined and discussed: vasospasm, seizures, rebleed, hydrocephalus, fever, anemia, hypertension, hypotension, hyperglycemia, hyponatremia, hypernatremia, cardiac abnormalities, pulmonary edema, venous thromboembolism, gastric ulceration, nosocomial infection, bloodstream infection/sepsis, and iatrogenic complications.

CONCLUSIONS

Although the intracranial complications of SAH can take priority in the initial management, the extracranial complications should be monitored for and recognized as early as possible because these complications can develop at varying times throughout the course of the condition. Therefore, a variety of investigations, as described by this article, should be undertaken on admission to maximize early recognition of any of the extracranial consequences. Furthermore, because the extracranial complications have a direct effect on clinical outcome and can lead to and exacerbate the intracranial complications, monitoring, recognizing, and managing these complications in parallel with the intracranial complications is important and would allow optimization of the patient's management and thus help improve their overall outcome.

Critical Evaluation of the Lund Concept for Treatment of Severe Traumatic Head Injury, 25 Years after Its Introduction

When introduced in 1992, the Lund concept (LC) was the first complete guideline for treatment of severe traumatic brain injury (s-TBI). It was a theoretical approach, based mainly on general physiological principles—i.e., of brain volume control and optimization of brain perfusion and oxygenation of the penumbra zone. The concept gave relatively strict outlines for cerebral perfusion pressure, fluid therapy, ventilation, sedation, nutrition, the use of vasopressors, and osmotherapy. The LC strives for treatment of the pathophysiological mechanisms behind symptoms rather than just treating the symptoms. The treatment is standardized, with less need for individualization. Alternative guidelines published a few years later (e.g., the Brain Trauma Foundation guidelines and European guidelines) were mainly based on meta-analytic approaches from clinical outcome studies and to some extent from systematic reviews. When introduced, they differed extensively from the LC. We still lack any large randomized outcome study comparing the whole concept of BTF guidelines with other guidelines including the LC. From that point of view, there is limited clinical evidence favoring any of the s-TBI guidelines used today. In principle, the LC has not been changed since its introduction. Some components of the alternative guidelines have approached those in the LC. In this review, I discuss some important principles of brain hemodynamics that have been lodestars during formulation of the LC. Aspects of ventilation, nutrition, and temperature control are also discussed. I critically evaluate the most important components of the LC 25 years after its introduction, based on hemodynamic principles and on the results of own an others experimental and human studies that have been published since then.

RBC Transfusion Improves Cerebral Oxygen Delivery in Subarachnoid Hemorrhage

OBJECTIVES

Impaired oxygen delivery due to reduced cerebral blood flow is the hallmark of delayed cerebral ischemia following subarachnoid hemorrhage. Since anemia reduces arterial oxygen content, it further threatens oxygen delivery increasing the risk of cerebral infarction. Thus, subarachnoid hemorrhage may constitute an important exception to current restrictive transfusion practices, wherein raising hemoglobin could reduce the risk of ischemia in a critically hypoperfused organ. In this physiologic proof-of-principle study, we determined whether transfusion could augment cerebral oxygen delivery, particularly in vulnerable brain regions, across a broad range of hemoglobin values.

DESIGN

Prospective study measuring cerebral blood flow and oxygen extraction fraction using O-PET. Vulnerable brain regions were defined as those with baseline oxygen delivery less than 4.5 mL/100 g/min.

SETTING

PET facility located within the Neurology/Neurosurgery ICU.

PATIENTS

Fifty-two patients at risk for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage with hemoglobin 7-13 g/dL.

INTERVENTIONS

Transfusion of one unit of RBCs over 1 hour.

MEASUREMENTS AND MAIN RESULTS

Baseline hemoglobin was 9.7 g/dL (range, 6.9-12.9), and cerebral blood flow was 43 ± 11 mL/100 g/min. After transfusion, hemoglobin rose from 9.6 ± 1.4 to 10.8 ± 1.4 g/dL (12%; p < 0.001) and oxygen delivery from 5.0 (interquartile range, 4.4-6.6) to 5.5 mL/100 g/min (interquartile range, 4.8-7.0) (10%; p = 0.001); the response was comparable across the range of hemoglobin values. In vulnerable brain regions, transfusion resulted in a greater (16%) rise in oxygen delivery associated with reduction in oxygen extraction fraction, independent of Hgb level (p = 0.002 vs normal regions).

CONCLUSIONS

This study demonstrates that RBC transfusion improves cerebral oxygen delivery globally and particularly to vulnerable regions in subarachnoid hemorrhage patients at risk for delayed cerebral ischemia across a wide range of hemoglobin values and suggests that restrictive transfusion practices may not be appropriate in this population. Large prospective trials are necessary to determine if these physiologic benefits translate into clinical improvement and outweigh the risk of transfusion.

Blood transfusion indications in neurosurgical patients: A systematic review

Neurosurgical procedures can be complicated by significant blood losses that have the potential to decrease tissue perfusion to critical brain tissue. Red blood cell transfusion is used in a variety of capacities both inside, and outside, of the operating room to prevent untoward neurologic damage. However, evidence-based guidelines concerning thresholds and indications for transfusion in neurosurgery remain limited. Consequently, transfusion practices in neurosurgical patients are highly variable and based on institutional experiences. Recently, a paradigm shift has occurred in neurocritical intensive care units, whereby restrictive transfusion is increasingly favored over liberal transfusion but the ideal strategy remains in clinical equipoise. The authors of this study perform a systematic review of the literature with the objective of capturing the changing landscape of blood transfusion indications in neurosurgical patients.

The effect of blood transfusion on central venous oxygen saturation in critically ill patients admitted to a neurointensive care unit

BACKGROUND

Literature suggests poorer outcomes during anaemia as well as following red blood cell transfusion (BT) in brain injured patients. Recently, central venous oxygen saturation (ScvO₂ ) has been proposed as a physiological trigger to guide red BT. In this study, we looked at ScvO₂ changes following BT in patients admitted to a neurointensive care unit (NICU).

STUDY DESIGN

In this prospective, observational study, adult, acutely ill neurological patients of >18 years were recruited. The following parameters were measured before and immediately after transfusion and then at 6, 12, 18 and 24 h after transfusion: haemoglobin (Hb), ScvO₂ and central venous oxygen partial pressure (PcvO₂ ) (blood sampled from central venous catheter). Simultaneously, hemodynamic parameters [central venous pressure (CVP), heart rate (HR), mean arterial pressure (MAP) and systolic blood pressure (SBP)] were also noted.

RESULTS

Data from 70 adult patients were analysed. Following BT, significant improvement was noted in Hb, ScvO₂ and all hemodynamic parameters. The ScvO₂ changes correlated significantly with the number of units of BT (P = 0·039), pre-transfusion Hb (P = 0·010), ScvO₂ (P = 0·001) and PcvO₂ (P = 0·001). When receiver operating characteristic (ROC) curves were drawn, optimum cut-off values of baseline ScvO₂ and Hb to predict the need for transfusion in terms of oxygen delivery were 70% and 8·6 gm dL^-1 respectively.

DISCUSSION

Baseline ScvO₂ <70% appears to be a useful physiological trigger for deciding the need for BT in brain injured patients. Whether improvement in ScvO₂ leads to improvement in regional brain oxygenation needs to be studied.

Precision medicine of aneurysmal subarachnoid hemorrhage, vasospasm and delayed cerebral ischemia

INTRODUCTION

Precision medicine provides individualized treatment of diseases through leveraging patient-to-patient variation. Aneurysmal subarachnoid hemorrhage carries tremendous morbidity and mortality with cerebral vasospasm and delayed cerebral ischemia proving devastating and unpredictable. Lack of treatment measures for these conditions could be improved through precision medicine. Areas covered: Discussed are the pathophysiology of CV and DCI, treatment guidelines, and evidence for precision medicine used for prediction and prevention of poor outcomes following aSAH. A PubMed search was performed using keywords cerebral vasospasm or delayed cerebral ischemia and either biomarkers, precision medicine, metabolomics, proteomics, or genomics. Over 200 peer-reviewed articles were evaluated. The studies presented cover biomarkers identified as predictive markers or therapeutic targets following aSAH. Expert commentary: The biomarkers reviewed here correlate with CV, DCI, and neurologic outcomes after aSAH. Though practical use in clinical management of aSAH is not well established, using these biomarkers as predictive tools or therapeutic targets demonstrates the potential of precision medicine.

Postoperative Cerebral Vasospasm Following Transsphenoidal Pituitary Adenoma Surgery

PURPOSE

Cerebral vasospasm following a transsphenoidal resection of a pituitary adenoma is a devastating occurrence that can lead to delayed cerebral ischemia and poor neurologic outcome if not diagnosed and treated in a timely manner. The etiology of this condition is not well understood but can lead to significant arterial vasospasm that causes severe ischemic insults. In this paper, we identify common presenting symptoms and essential management strategies to treat this harmful disease.

METHODS

A retrospective case report and literature review of presentation, treatment, and outcome of cerebral vasospasm following transsphenoidal surgery.

RESULTS

We present 1 case and review 12 known cases in the literature on vasospasm following transsphenoidal surgery. Mean age was 48 (±13.8) years. There were 46.2% male patients. Factors associated with vasospasm, such as cerebral spinal fluid leaks following surgery, were seen in 38.5% of cases, and postoperative subarachnoid hemorrhage (SAH) was seen in 84.6% of cases. Hemiparesis was the presenting symptom of delayed cerebral ischemia in 61.5% of cases. For management, maintaining at least a euvolemic volume status was used in 76.9%, induced hypertension was used in 61.5%, and nimodipine was administered in 46.2% of cases. Patients returned to their neurologic baseline in 61.5% of cases, had new permanent deficits in 7.7% of cases, and died in 30.8% of cases.

CONCLUSION

Cerebral vasospasm following transsphenoidal surgery is a dangerous disease that can lead to a high likelihood of mortality if not identified and treated. Early postoperative events, such as peritumoral subarachnoid hemorrhage and hemiparesis, may be factors associated with post-transsphenoidal surgery vasospasm. Effective treatment options used in patients that regained complete neurologic recovery were by inducing hypertension, maintaining euvolemia, and administering nimodipine.

Hypoxemia, oxygen content, and the regulation of cerebral blood flow

This review highlights the influence of oxygen (O2) availability on cerebral blood flow (CBF). Evidence for reductions in O2 content (CaO2 ) rather than arterial O2 tension (PaO2 ) as the chief regulator of cerebral vasodilation, with deoxyhemoglobin as the primary O2 sensor and upstream response effector, is discussed. We review in vitro and in vivo data to summarize the molecular mechanisms underpinning CBF responses during changes in CaO2 . We surmise that 1) during hypoxemic hypoxia in healthy humans (e.g., conditions of acute and chronic exposure to normobaric and hypobaric hypoxia), elevations in CBF compensate for reductions in CaO2 and thus maintain cerebral O2 delivery; 2) evidence from studies implementing iso- and hypervolumic hemodilution, anemia, and polycythemia indicate that CaO2 has an independent influence on CBF; however, the increase in CBF does not fully compensate for the lower CaO2 during hemodilution, and delivery is reduced; and 3) the mechanisms underpinning CBF regulation during changes in O2 content are multifactorial, involving deoxyhemoglobin-mediated release of nitric oxide metabolites and ATP, deoxyhemoglobin nitrite reductase activity, and the downstream interplay of several vasoactive factors including adenosine and epoxyeicosatrienoic acids. The emerging picture supports the role of deoxyhemoglobin (associated with changes in CaO2 ) as the primary biological regulator of CBF. The mechanisms for vasodilation therefore appear more robust during hypoxemic hypoxia than during changes in CaO2 via hemodilution. Clinical implications (e.g., disorders associated with anemia and polycythemia) and future study directions are considered.

Improved survival after non-traumatic subarachnoid haemorrhage with structured care pathways and modern intensive care

OBJECTIVE

Patients with subarachnoid haemorrhage (SAH) often require multidisciplinary management and their treatment is difficult to standardize. The aim was to describe baseline characteristics, care pathways and discharge status in an unselected group of patients with first ever non-traumatic SAH, and to examine whether their care pathways and outcomes vary.

METHODS

Patients admitted with first ever non-traumatic SAH to a neurosurgical unit (NSU) in Sweden during a period of 18 months in 2009-2010 were included. The data was retrospectively collected from patient charts.

RESULTS

A total of 131 patients were admitted with first ever non-traumatic SAH. Forty-nine (37%) patients initially sought medical care nearby the NSU and 82 (63%) in other parts of the catchment area. The average age was 55.5 years and 79 (60%) were female. In 98 (75%) cases, a ruptured aneurysm was found to be the cause of SAH. There was a significant correlation between poor clinical grade at admission and poor patient outcome (p<0.0005). No significant correlation between early aneurysm treatment and improved clinical outcome were seen. No significant differences in outcome were seen between patients who initially sought medical care nearby the NSU and those in other parts of the catchment area. There was no difference seen in the number of patients who had follow-up at the NSU depending on where they initially sought help.

CONCLUSION

This study shows an improvement in survival after SAH compared to earlier studies in Sweden. The results are indicative of effective management of all patients with SAH in the catchment area that are treated at the NSU. A nationwide registry to assess the overall management of patients treated for SAH would be useful to further investigate patients with SAH.

Temporal Profiles of Cerebral Perfusion Pressure After Subarachnoid Hemorrhage

INTRODUCTION

Insufficient cerebral perfusion pressure (CPP) after aneurysmal subarachnoid hemorrhage can impair cerebral blood flow. We examined the temporal profiles of CPP change and tested whether these profiles were associated with delayed cerebral ischemia (DCI).

METHOD

CPP values were retrospectively reviewed for 238 subjects. Intracranial pressure and mean arterial pressure values were obtained every 2 hours for 14 days. Induced hypertension was utilized to prevent vasospasm. The linear and quadratic CPP changes over time were tested using growth curve analysis. Multivariable logistic regression was utilized to examine the association between DCI and percentages of CPP values of >110, >100, <70, and <60 mm Hg. DCI was defined as neurological deterioration because of impaired cerebral blood flow.

RESULTS

Between-subject differences accounted for 39% of variation in CPP values. There was a significant linear increase in CPP values over time (β = 0.06, SE = 0.006, p < .001). The covariance (-0.52, SE = 0.09, p < .001) between initial CPP and linear parameter was negative, indicating that subjects with high CPP on admission had a slower rate of increase whereas those with low CPP had a faster rate of increase. For every 10% increase in the proportion of CPP of >100 or >110 mm Hg, the odds of DCI increased by 1.21 and 1.43, respectively (p < .05).

CONCLUSIONS

The longer the time patients spent with high CPP, the greater the odds for DCI. When used prophylactically, induced hypertension contributes to higher CPP values. On the basis of the CPP trends and correlations observed, induced hypertension may not confer expected benefits in patients with aneurysmal subarachnoid hemorrhage.

Cerebral Vasospasm in Critically III Patients with Aneurysmal Subarachnoid Hemorrhage: Does the Evidence Support the Ever-Growing List of Potential Pharmacotherapy Interventions?

The occurrence of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is a significant event resulting in decreased cerebral blood flow and oxygen delivery. Prevention and treatment of cerebral vasospasm is vital to avert neurological damage and reduced functional outcomes. A variety of pharmacotherapy interventions for the prevention and treatment of cerebral vasospasm have been evaluated. Unfortunately, very few large randomized trials exist to date, making it difficult to make clear recommendations regarding the efficacy and safety of most pharmacologic interventions. Considerable debate exists regarding the efficacy and safety of hypervolemia, hemodilution, and hypertension (triple-H therapy), and the implementation of each component varies substantially amongst institutions. There is a new focus on euvolemic-induced hypertension as a potentially preferred mechanism of hemodynamic augmentation. Nimodipine is the one pharmacologic intervention that has demonstrated favorable effects on patient outcomes and should be routinely administered unless contraindications are present. Intravenous nicardipine may offer an alternative to oral nimodipine. The addition of high-dose magnesium or statin therapy has shown promise, but results of ongoing large prospective studies are needed before they can be routinely recommended. Tirilazad and clazosentan offer new pharmacologic mechanisms, but clinical outcome results from prospective randomized studies have largely been unfavorable. Locally administered pharmacotherapy provides a targeted approach to the treatment of cerebral vasospasm. However, the paucity of data makes it challenging to determine the most appropriate therapy and implementation strategy. Further studies are needed for most pharmacologic therapies to determine whether meaningful efficacy exists.

Current options for the management of aneurysmal subarachnoid hemorrhage-induced cerebral vasospasm: a comprehensive review of the literature

OBJECTIVES

Cerebral vasospasm is one of the leading causes of morbi-mortality following aneurysmal subarachnoid hemorrhage. The aim of this article is to discuss the current status of vasospasm therapy with emphasis on endovascular treatment.

METHODS

A comprehensive review of the literature obtained by a PubMed search. The most relevant articles related to medical, endovascular and alternative therapies were selected for discussion.

RESULTS

Current accepted medical options include the oral nimodipine and 'triple-H' therapy (hypertension, hypervolemia and hemodilution). Nimodipine remains the only modality proven to reduce the incidence of infarction. Although widely used, 'triple-H' therapy has not been demonstrated to significantly change overall outcome after cerebral vasospasm. Indeed, both induced hypervolemia and hemodilution may have deleterious effects, and more recent physiologic data favor normovolemia with induced hypertension or optimization of cardiac output. Endovascular options include percutaneous transluminal balloon angioplasty (PTA) and intra-arterial (IA) infusion of vasodilators. Multiple case reports and case series have been encountered in the literature using different drug regimens with diverse mechanisms of action. Compared with PTA, IA drug infusion has the advantages of distal penetration and a better safety profile. Its main disadvantages are the more frequent need for repeat treatments and its systemic hemodynamic repercussions. Alternative options using intraventricular/cisternal drug therapy and flow augmentation strategies have also shown possible benefits; however, their use is not yet as well established.

CONCLUSION

Blood pressure or cardiac output optimization should be the mainstay of hyperdynamic therapy. Endovascular treatment appears to have a positive impact on neurological outcome compared with the natural history of the disease. The role of intraventricular therapy and flow augmentation strategies in association with medical and endovascular treatment may, in the future, play a growing role in the management of patients with severe refractory vasospasm.

Treatment of intracranial vasospasm following subarachnoid hemorrhage

Vasospasm has been a long known source of delayed morbidity and mortality in aneurysmal subarachnoid hemorrhage patients. Delayed ischemic neurologic deficits associated with vasospasm may account for as high as 50% of the deaths in patients who survive the initial period after aneurysm rupture and its treatment. The diagnosis and treatment of vasospasm has still been met with some controversy. It is clear that subarachnoid hemorrhage is best cared for in tertiary care centers with modern resources and access to cerebral angiography. Ultimately, a high degree of suspicion for vasospasm must be kept during ICU care, and any signs or symptoms must be investigated and treated immediately to avoid permanent stroke and neurologic deficit. Treatment for vasospasm can occur through both ICU intervention and endovascular administration of intra-arterial vasodilators and balloon angioplasty. The best outcomes are often attained when these methods are used in conjunction. The following article reviews the literature on cerebral vasospasm and its treatment and provides the authors’ approach to treatment of these patients.

Current controversies in the prediction, diagnosis, and management of cerebral vasospasm: where do we stand?

Aneurysmal subarachnoid hemorrhage occurs in approximately 30,000 persons in the United States each year. Around 30 percent of patients with aneurysmal subarachnoid hemorrhage suffer from cerebral ischemia and infarction due to cerebral vasospasm, a leading cause of treatable death and disability following aneurysmal subarachnoid hemorrhage. Methods used to predict, diagnose, and manage vasospasm are the topic of recent active research. This paper utilizes a comprehensive review of the recent literature to address controversies surrounding these topics. Evidence regarding the effect of age, smoking, and cocaine use on the incidence and outcome of vasospasm is reviewed. The abilities of different computed tomography grading schemes to predict vasospasm in the aftermath of subarachnoid hemorrhage are presented. Additionally, the utility of different diagnostic methods for the detection and visualization of vasospasm, including transcranial Doppler ultrasonography, CT angiography, digital subtraction angiography, and CT perfusion imaging is discussed. Finally, the recent literature regarding interventions for the prophylaxis and treatment of vasospasm, including hyperdynamic therapy, albumin, calcium channel agonists, statins, magnesium sulfate, and endothelin antagonists is summarized. Recent studies regarding each topic were reviewed for consensus recommendations from the literature, which were then presented.

Is asymptomatic vasospasm associated with poor outcome in subarachnoid hemorrhage?

BACKGROUND

Vasospasm occurs in up to 70% of aneurysmal subarachnoid hemorrhage (aSAH), but only half becomes symptomatic. It is unclear whether asymptomatic vasospasm (AV) detected by noninvasive testing affects outcome. Prophylactic hemodilutional, hypertensive, and hypervolemic (HHH) therapy is widely used but the benefit remains unproven. We aim to determine whether AV increases the risk of poor outcome and whether HHH is safe.

METHODS

A total of 175 consecutive patients with aSAH without clinical vasospasm were included. Patients with sonographic (transcranial doppler) or radiologic (computed tomography [CT] Angiography) vasospasm were assigned to AV group, while those without were assigned to no vasospasm (NV) group. Logistic regression was used to determine the association between AV and HHH on poor outcome, defined as modified Rankin scale (mRS) >3 at discharge or 3 to 6 months' follow-up.

RESULTS

In all, 106 patients had NV and 25 received HHH. A total of 69 patients had AV and 54 received HHH. Asymptomatic vasospasm compared to NV was not associated with poor outcome (odds ratio [OR] 2.6, 95% confidence interval [CI]: 0.75-8.9; P = .1). Hemodilutional, hypertensive, and hypervolemic use in patients with AV did not improve the outcome (OR 0.16, 95%CI: 0.009-2.84; P = .2). In patients with NV, HHH use showed trend toward poor outcome after multivariable adjustment (OR 12.6, 95%CI: 1.08-146.5 P = .04).

CONCLUSION

Asymptomatic vasospasm does not appear to be associated with poor outcome in aSAH. Hemodilutional, hypertensive, and hypervolemic therapy in AV was not associated with improved outcome and may be harmful to patients who do not have vasospasm. Further research is needed to validate this finding.

Parenchymal brain oxygen monitoring in the neurocritical care unit

Patients admitted to the neurocritical care unit (NCCU) often have serious conditions that can be associated with high morbidity and mortality. Pharmacologic agents or neuroprotectants have disappointed in the clinical environment. Current NCCU management therefore is directed toward identification, prevention, and treatment of secondary cerebral insults that evolve over time and are known to aggravate outcome. This strategy is based on a variety of monitoring techniques including use of intraparenchymal monitors. This article reviews parenchymal brain oxygen monitors, including the available technologies, practical aspects of use, the physiologic rationale behind their use, and patient management based on brain oxygen.

HIMALAIA (Hypertension Induction in the Management of AneurysmaL subArachnoid haemorrhage with secondary IschaemiA): a randomized single-blind controlled trial of induced hypertension vs. no induced hypertension in the treatment of delayed cerebral ischemia after subarachnoid hemorrhage

RATIONALE

Delayed cerebral ischemia (DCI) is a major complication after aneurysmal subarachnoid hemorrhage (SAH). One option to treat delayed cerebral ischemia is to use induced hypertension, but its efficacy on the eventual outcome has not been proven in a randomized clinical trial. This article describes the design of the HIMALAIA trial (Hypertension Induction in the Management of AneurysmaL subArachnoid haemorrhage with secondary IschaemiA), designed to assess the effectiveness of induced hypertension on neurological outcome in patients with DCI after SAH.

AIMS

To investigate whether induced hypertension improves the functional outcome in patients with delayed cerebral ischemia after SAH.

DESIGN

The HIMALAIA trial is a multicenter, singe-blinded, randomized controlled trial in patients with DCI after a recent SAH. Eligible patients will be randomized to either induced hypertension (n = 120) or to no induced hypertension (n = 120). In selected centers, the efficacy of induced hypertension in augmenting cerebral blood flow will be measured by means of cerebral perfusion computerized tomography scanning. Follow-up assessments will be performed at 3 and 12 months after randomization by trial nurses who are blinded to the treatment allocation and management. We will include patients during five years.

STUDY OUTCOMES

The primary outcome is the proportion of subarachnoid hemorrhage patients with delayed cerebral ischemia with poor outcome three-months after randomization, defined as a modified Rankin scale of more than 3. Secondary outcome measures are related to treatment failure, functional outcome, adverse events, and cerebral hemodynamics. The HIMALAIA trial is registered at clinicaltrials.gov under identifier NCT01613235.

Update on the management of subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular disease. Outcome after SAH is mainly determined by the initial severity of the hemorrhage. Neuroimaging, in particular computed tomography, and aneurysm repair techniques, such as coiling and clipping, as well as neurocritical care management, have improved during the last few years. The management of a patient with SAH should have an interdisciplinary approach with case discussions between the neurointensivist, interventionalist and the neurosurgeon. The patient should be treated in a specialized neurointensive care unit of a center with sufficient SAH case volume. Poor-grade patients can be observed for complications and delayed cerebral ischemia through continuous monitoring techniques in addition to transcranial Doppler ultrasonography such as continuous electroencephalography, brain tissue oxygenation, cerebral metabolism, cerebral blood flow and serial vascular imaging. Neurocritical care should focus on neuromonitoring for delayed cerebral ischemia, management of hydrocephalus, seizures and intracranial hypertension, as well as of medical complications such as hyperglycemia, fever and anemia.

The association between fluid balance and outcomes after subarachnoid hemorrhage

BACKGROUND

We sought to determine the association between early fluid balance and neurological/vital outcome of patients with subarachnoid hemorrhage.

METHODS

Hospital admission, imaging, ICU and outcome data were retrospectively collected from the medical records of adult patients with aneurysmal SAH admitted to a level-1 trauma and stroke referral center during a 5-year period. Two groups were identified based on cumulative fluid balance by ICU day 3: (i) patients with a positive fluid balance (n = 221) and (ii) patients with even or negative fluid balance (n = 135). Multivariable logistic regression was used to adjust for age, Hunt-Hess and Fisher scores, mechanical ventilation and troponin elevation (>0.40 ng/ml) at ICU admission. The primary outcome was a composite of hospital mortality or new stroke.

RESULTS

Patients with positive fluid balance had worse admission GCS and Hunt-Hess score, and by ICU day 3 had cumulatively received more IV fluids, but had less urine output when compared with the negative fluid balance group. There was no difference in the odds of hospital death or new stroke (adjusted OR: 1.47, 95%CI: 0.85, 2.54) between patients with positive and negative fluid balance. However, positive fluid balance was associated with increased odds of TCD vasospasm (adjusted OR 2.25, 95%CI: 1.37, 3.71) and prolonged hospital length of stay.

CONCLUSIONS

Although handling of IV fluid administration was not an independent predictor of mortality or new stroke, patients with early positive fluid balance had worse clinical presentation and had greater resource use during the hospital course.

Contemporary view on neuromonitoring following severe traumatic brain injury

Evolving brain damage following traumatic brain injury (TBI) is strongly influenced by complex pathophysiologic cascades including local as well as systemic influences. To successfully prevent secondary progression of the primary damage we must actively search and identify secondary insults e.g. hypoxia, hypotension, uncontrolled hyperventilation, anemia, and hypoglycemia, which are known to aggravate existing brain damage. For this, we must rely on specific cerebral monitoring. Only then can we unmask changes which otherwise would remain hidden, and prevent adequate intensive care treatment. Apart from intracranial pressure (ICP) and calculated cerebral perfusion pressure (CPP), extended neuromonitoring (SjvO₂, ptiO₂, microdialysis, transcranial Doppler sonography, electrocorticography) also allows us to define individual pathologic ICP and CPP levels. This, in turn, will support our therapeutic decision-making and also allow a more individualized and flexible treatment concept for each patient. For this, however, we need to learn to integrate several dimensions with their own possible treatment options into a complete picture. The present review summarizes the current understanding of extended neuromonitoring to guide therapeutic interventions with the aim of improving intensive care treatment following severe TBI, which is the basis for ameliorated outcome.