Randomized, controlled trial on the effect of a 20% mannitol solution and a 7.5% saline/6% dextran solution on increased intracranial pressure after brain injury*

Initial approach to the hyponatremic patient

Hyponatremia with cerebral symptoms is a medical emergency in which treatment delay may prove fatal. However, controversy prevails over which treatment is the best. This paper presents a practical and unified approach based on a literature study of the physiology of plasma [Na(+) ], the brain's response and clinical and experimental studies. Experimental and clinical studies were thoroughly reviewed. The literature was identified through MESH and free text search in the databases PubMed, Embase and Cochrane, and references in the literature. Cerebral water homeostasis is pivotal in hyponatremia. Prompt, repeated boluses of 2 ml/kg 3% saline constitute a rational treatment of symptomatic hyponatremia. After the initial correction, concern is mainly with avoiding overcorrection and osmotic demyelination. Plasma [Na(+)] is determined by the external balances of water and cations. The water balance must therefore be carefully monitored to counter the dramatic increase in plasma [Na(+)] that may result from brisk diuresis. Definitive treatment of hyponatremia should be directed toward its etiology. This can be challenging and the clinical application of traditional classifications based on hydration is difficult. Therefore, a practical approach is proposed based on the mechanisms of impaired urine dilution.

CONCLUSIONS

The conflict between previously opposing standpoints is gradually giving way to an emerging consensus: Prompt bolus treatment of symptomatic hyponatremia with hypertonic saline. After the initial treatment, overcorrection must be avoided. Definitive treatment should be directed toward the nature of the underlying disorder. An approach based on the mechanism governing the impaired urine dilution has been proposed.

A comparative study on the efficacy of 10% hypertonic saline and equal volume of 20% mannitol in the treatment of experimentally induced cerebral edema in adult rats

Background

Hypertonic saline and mannitol are commonly used in the treatment of cerebral edema and elevated intracranial pressure (ICP) at present. In this connection, 10% hypertonic saline (HS) alleviates cerebral edema more effectively than the equal volume of 20% mannitol. However, the exact underlying mechanism for this remains obscure. This study aimed to explore the possible mechanism whereby 10% hypertonic saline can ameliorate cerebral edema more effectively than mannitol.

Results

Adult male Sprague-Dawley (SD) rats were subjected to permanent right-sided middle cerebral artery occlusion (MCAO) and treated with a continuous intravenous infusion of 10% HS, 20% mannitol or D-[1-³H(N)]-mannitol. Brain water content (BWC) as analyzed by wet-to-dry ratios in the ischemic hemisphere of SD rats decreased more significantly after 10% HS treatment compared with 20% mannitol. Concentration of serum Na⁺ and plasma crystal osmotic pressure of the 10% HS group at 2, 6, 12 and 18 h following permanent MCAO increased significantly when compared with 20% mannitol treated group. Moreover, there was negative correlation between the BWC of the ipsilateral ischemic hemisphere and concentration of serum Na⁺, plasma crystal osmotic pressure and difference value of concentration of serum Na⁺ and concentration of brain Na⁺ in ipsilateral ischemic hemisphere in the 10% HS group at the various time points after MCAO. A remarkable finding was the progressive accumulation of mannitol in the ischemic brain tissue.

Conclusions

We conclude that 10% HS is more effective in alleviating cerebral edema than the equal volume of 20% mannitol. This is because 10% HS contributes to establish a higher osmotic gradient across BBB and, furthermore, the progressive accumulation of mannitol in the ischemic brain tissue counteracts its therapeutic efficacy on cerebral edema.

Fluid balance, complications, and brain tissue oxygen tension monitoring following severe traumatic brain injury

BACKGROUND

Refractory intracranial hypertension (RIH) frequently complicates severe traumatic brain injury (TBI) and is associated with worse outcomes. Aggressive fluid resuscitation contributes to the development of peripheral and pulmonary edema, but an effect on cerebral edema is not well established. Some clinicians, including advocates of the "Lund Concept", practice fluid restriction as a means of limiting cerebral edema and reducing intracranial pressure (ICP).

METHODS

We performed a retrospective cohort study involving 41 consecutive patients with severe TBI to assess the association between fluid balance and the development of RIH or pulmonary complications.

RESULTS

There was no difference in cumulative fluid balance between patients who did, or did not, develop RIH. Patients in the tertile with the largest fluid balance were no more likely to develop RIH than those in the more restrictive groups (HR 1.05, 0.78-1.42, P = 0.73). In contrast, there was a strong association between fluid balance and the development of bilateral pulmonary infiltrates, which persisted even after adjusting for Glasgow Coma Scale and Injury Severity Score (HR 1.69, 1.40-2.04, P < 0.0001). The use of P(bt)O(2) monitors to guide therapy was associated with higher cumulative fluid balance, more vasopressor use, and the development of both pulmonary edema and RIH.

CONCLUSION

We found no association between cumulative fluid balance and the development of RIH. However, more judicious volume management has the potential to reduce the occurrence of pulmonary complications. Further research is needed to clarify optimal approaches to fluid management among patients with severe TBI and to guide the interpretation and integration of information derived from P(bt)O(2) monitors.

Acute management of acquired brain injury part II: an evidence-based review of pharmacological interventions

PRIMARY OBJECTIVE

To review the research literature on pharmacological interventions used in the acute phase of acquired brain injury (ABI) to manage ICP and improve neural recovery.

MAIN OUTCOMES

A literature search of multiple databases (CINAHL, EMBASE, MEDLINE and PSYCHINFO) and hand searched articles covering the years 1980-2008 was performed. Peer reviewed articles were assessed for methodological quality using the PEDro scoring system for randomized controlled trials (RCTs) and the Downs and Black tool for RCTs and non-randomized trials. Levels of evidence were assigned and recommendations were made.

RESULTS

In total, 11 pharmacological interventions used in the acute management of ABI were evaluated. These included propofol, barbiturates, opioids, midazolam, mannitol, hypertonic saline, corticosteroids, progesterone, bradykinin antagonists, dimethyl sulphoxide and cannabinoids. Of these interventions, corticosteroids were found to be contraindicated and cannabinoids were reported as ineffective. The other nine interventions demonstrated some benefit for treatment of acute ABI. However, rarely did these benefits result in improved long-term patient outcomes.

CONCLUSIONS

Substantial research has been devoted to evaluating the use of pharmacological interventions in the acute management of ABI. However, much of this research has focused on the application of individual interventions in small single-site trials. Future research will need to establish larger patient samples to evaluate the benefits of combined interventions within specific patient populations.

[Hypernatremia in neurointensive care]

Hypernatremia invariably denotes hyperosmolarity and, at least transiently, causes cellular dehydration. Because of blood brain barrier properties, cerebral tissue volume is modified by acute changes in osmolarity. An acute hyperosmolarity (by intravenous sodium or mannitol) temporally decreases intracranial pressure. This treatment is thus useful in critical situations, allowing time for diagnosis and, if possible, other treatment. But in cases of sustained hypernatremia, cellular dehydration is rapidly counterbalanced by an increase in cellular osmolarity. For the brain, it has been shown that cerebral volume is restored in a few hours during prolonged hypernatremia. Moreover, the plasmatic osmotic load induces an increase in diuresis and natriuresis. A tight control is then necessary to prevent hypovolemia and electrolytes disorders. Teams using this treatment should undertake controlled randomized studies to ascertain any beneficial effect that cannot be explained by physiology.

Hemodynamic support of the trauma patient

PURPOSE OF REVIEW

The aim of this review is to address and summarize some key issues and recent insights into the hemodynamic support of the trauma patient related to fluid administration.

RECENT FINDINGS

Colloids are not superior to crystalloids in treating hypovolemia in the trauma patient and show no survival benefit. Furthermore, several adverse effects (renal failure, bleeding complications and anaphylaxis) have been reported with the use of artificial colloids. Hypertonic saline is effective and well tolerated in the treatment of hypovolemic shock and traumatic brain injury. Potential benefits are reduced fluid requirements and immune modulation. Resuscitation strategies should depend on the type of injury (penetrating vs. blunt; concomitant brain injury). Excessive fluid resuscitation, which can cause acute respiratory distress syndrome, abdominal compartment syndrome and brain edema, should be avoided. Dynamic parameters to guide volume therapy are probably more reliable than static parameters and minimally invasive techniques to monitor the microcirculation are becoming more important to determine the endpoints of resuscitation.

SUMMARY

Hemodynamic support is an early goal in the treatment of the trauma patient. The use of crystalloids is currently recommended in trauma resuscitation. The amount of fluid we give should be tailored to the individual trauma patient in which clear endpoints of resuscitation are of vital importance to maximize the chances of survival.

Managing hyponatremia in patients with syndrome of inappropriate antidiuretic hormone secretion

This review will address the management of hyponatremia caused by the syndrome of inappropriate antidiuretic hormone secretion (SIADH) in hospitalized patients. To do so requires an understanding of the pathogenesis and diagnosis of SIADH, as well as currently available treatment options. The review will be structured as responses to a series of questions, followed by a presentation of an algorithm for determining the most appropriate treatments for individual patients with SIADH based on their presenting symptoms.

Management of bleeding following major trauma: an updated European guideline

INTRODUCTION

Evidence-based recommendations are needed to guide the acute management of the bleeding trauma patient, which when implemented may improve patient outcomes.

METHODS

The multidisciplinary Task Force for Advanced Bleeding Care in Trauma was formed in 2005 with the aim of developing a guideline for the management of bleeding following severe injury. This document presents an updated version of the guideline published by the group in 2007. Recommendations were formulated using a nominal group process, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) hierarchy of evidence and based on a systematic review of published literature.

RESULTS

Key changes encompassed in this version of the guideline include new recommendations on coagulation support and monitoring and the appropriate use of local haemostatic measures, tourniquets, calcium and desmopressin in the bleeding trauma patient. The remaining recommendations have been reevaluated and graded based on literature published since the last edition of the guideline. Consideration was also given to changes in clinical practice that have taken place during this time period as a result of both new evidence and changes in the general availability of relevant agents and technologies.

CONCLUSIONS

This guideline provides an evidence-based multidisciplinary approach to the management of critically injured bleeding trauma patients.

A comparison of 3% hypertonic saline and mannitol for brain relaxation during elective supratentorial brain tumor surgery

BACKGROUND

In this study, we compared the effects of 3% hypertonic saline (HTS) and 20% mannitol on brain relaxation during supratentorial brain tumor surgery, intensive care unit (ICU) stays, and hospital days.

METHODS

This prospective, randomized, and double-blind study included patients who were selected for elective craniotomy for supratentorial brain tumors. Patients received either 160 mL of 3% HTS (HTS group, n = 122) or 150 mL of 20% mannitol infusion (M group, n = 116) for 5 minutes at the start of scalp incision. The PCO(2) in arterial blood was maintained within 35 to 40 mm Hg, arterial blood pressure was controlled within baseline values +/-20%, and positive fluid balance was maintained intraoperatively at a rate of 2 mL/kg/h. Outcome measures included fluid input, urine output, arterial blood gases, serum sodium concentration, ICU stays, and hospital days. Surgeons assessed the condition of the brain as "tight," "adequate," or "soft" immediately after opening the dura.

RESULTS

Brain relaxation conditions in the HTS group (soft/adequate/tight, n = 58/43/21) were better than those observed in the M group (soft/adequate/tight, n = 39/42/35; P = 0.02). The levels of serum sodium were higher in the HTS group compared with the M group over time (P < 0.001). The average urine output in the M group (707 mL) was higher than it was in the HTS group (596 mL) (P < 0.001). There were no significant differences in fluid input, ICU stays, and hospital days between the 2 groups.

CONCLUSIONS

Our results suggest that HTS provided better brain relaxation than did mannitol during elective supratentorial brain tumor surgery, whereas it did not affect ICU stays or hospital days.

Hypertonic saline and its effect on intracranial pressure, cerebral perfusion pressure, and brain tissue oxygen

OBJECTIVE

Hypertonic saline is emerging as a potentially effective single osmotic agent for control of acute elevations in intracranial pressure (ICP) caused by severe traumatic brain injury. This study examines its effect on ICP, cerebral perfusion pressure (CPP), and brain tissue oxygen tension (PbtO2).

METHODS

Twenty-five consecutive patients with severe traumatic brain injury who were treated with 23.4% NaCl for elevated ICP were evaluated. Bolt catheter probes were placed in the noninjured hemisphere, and hourly ICP, mean arterial pressure, CPP, and PbtO2 values were recorded. Thirty milliliters of 23.4% NaCl was infused over 15 minutes for intracranial hypertension, defined as ICP greater than 20 mm Hg. Twenty-one male patients and 4 female patients aged 16 to 64 years were included. The mean presenting Glasgow Coma Scale score was 5.7.

RESULTS

Mean pretreatment values included an ICP level of 25.9 mm Hg and a PbtO2 value of 32 mm Hg. The posttreatment ICP level was decreased by a mean of 8.3 mm Hg (P < 0.0001), and there was an improvement in PbtO2 of 3.1 mm Hg (P < 0.01). ICP of more than 31 mm Hg decreased by 14.2 mm Hg. Pretreatment CPP values of less than 70 mm Hg increased by a mean of 6 mm Hg (P < 0.0001). No complications occurred from this treatment, with the exception of electrolyte and chemistry abnormalities. At 6 months postinjury, the mortality rate was 28%, with 48% of patients achieving a favorable outcome by the dichotomized Glasgow Outcome Scale.

CONCLUSION

Hypertonic saline as a single osmotic agent decreased ICP while improving CPP and PbtO2 in patients with severe traumatic brain injury. Patients with higher baseline ICP and lower CPP levels responded to hypertonic saline more significantly.

Hypertonic saline in critical care: a review of the literature and guidelines for use in hypotensive states and raised intracranial pressure

Hypertonic saline has been in clinical use for many decades. Its osmotic and volume-expanding properties make it theoretically useful for a number of indications in critical care. This literature review evaluates the use of hypertonic saline in critical care. The putative mechanism of action is presented, followed by a narrative review of its clinical usefulness in critical care. The review was conducted using the Scottish Intercollegiate Guidelines Network method for the review of cohort studies, randomised-controlled trials and meta-analyses. The review focuses specifically on blood pressure restoration and outcome benefit in both haemorrhagic and non-haemorrhagic shock, and the management of raised intracranial pressure. Issues of clinical improvement and outcome benefit are addressed. Hypertonic saline solutions are effective for blood pressure restoration in haemorrhagic, but not other, types of shock. There is no survival benefit with the use of hypertonic saline solutions in shock. Hypertonic saline solutions are effective at reducing intracranial pressure in conditions causing acute intracranial hypertension. There is no survival or outcome benefit with the use of hypertonic saline solutions for raised intracranial pressure. Recommendations for clinical use and future directions of clinical research are presented.

Management of intracranial hypertension

Raised intracranial pressure (ICP) is a life threatening condition that is common to many neurological and non-neurological illnesses. Unless recognized and treated early it may cause secondary brain injury due to reduced cerebral perfusion pressure (CPP), and progress to brain herniation and death. Management of raised ICP includes care of airway, ventilation and oxygenation, adequate sedation and analgesia, neutral neck position, head end elevation by 20 degrees-30 degrees, and short-term hyperventilation (to achieve PCO(2) 32-35 mm Hg) and hyperosmolar therapy (mannitol or hypertonic saline) in critically raised ICP. Barbiturate coma, moderate hypothermia and surgical decompression may be helpful in refractory cases. Therapies aimed directly at keeping ICP <20 mmHg have resulted in improved survival and neurological outcome. Emerging evidence suggests that cerebral perfusion pressure targeted therapy may offer better outcome than ICP targeted therapies.

Patterns of increased intracranial pressure after severe traumatic brain injury

INTRODUCTION

Secondary brain injury due to increased intracranial pressure (ICP) contributes to post-traumatic morbidity and mortality. Although it is often taught that increased ICP begins early after traumatic brain injury, some patients develop increased ICP after the first 3 days post-injury. We examined our data to describe temporal patterns of increased ICP.

METHODS

This is a retrospective review of prospectively collected physiologic and demographic data.

RESULTS

Seventy-seven patients were included. We identified four patterns of increased ICP: beginning within 72 h (early), beginning after 72 h (late), early increases with resolution, and then a second rise after 72 h (bimodal), and continuously increased ICP. Late increases in ICP occur in 17% of this cohort. Peak day of swelling was day 7 for the "late" rise group and day 4 for the other patients with increased ICP. Forty-four percent of patients showed enlargement of cerebral contusions on follow-up imaging at 24 h post-injury.

CONCLUSIONS

Late rises in ICP were not rare in this cohort. This is clinically relevant as it may impact decisions about ICP monitor removal. Differences between groups in age, CT patterns of injury, fluid therapy, osmotic use, and fever were not statistically significant.

Severe head injury: clinicians' awareness of the literature

OBJECTIVES

1. To determine the awareness of the literature concerning therapeutic manoeuvres in severe closed head injury (CHI) among Canadian critical care clinicians and neurosurgeons, 2. To identify factors that affect utilization of these manoeuvres, and 3. To compare reported appropriateness and frequency of use with #1 and #2.

METHODS

The study design was a systematic scenario-based survey of all neurosurgeons and critical care physicians treating patients with severe CHI in Canada.

RESULTS

Fifty-nine of 99 neurosurgeons and 82 of 148 critical care physicians responded (57%). The majority of respondents were not able to identify the highest level of published evidence for most manoeuvres, except for the avoidance of corticosteroids (51%). The factor identified by most respondents as being most important in motivating use of any given manoeuvres was the level of published evidence (25%). Although reported appropriateness and frequency of use of most manoeuvres correlated well with each other, they did not correlate with awareness of evidence. In the case of corticosteroids, there was a strong correlation between non-use of steroids and awareness of evidence (R = -0.30, p = 0.0003).

CONCLUSIONS

Respondents to this survey of Canadian physicians treating patients with severe head injury reported published evidence as being the most significant factor affecting use of a therapy. However, most respondents did not correctly identify the highest published level of evidence for most therapies. This study has identified difficulty with research translation that may have clinical implications.

Hypertonic saline reduces neutrophil-epithelial interactions in vitro and gut tissue damage in a mouse model of colitis

Transepithelial migration of polymorphonuclear neutrophils (PMN) plays a crucial role in inflammatory conditions of the intestine, such as inflammatory bowel diseases. Hypertonic saline (HS) exerts various inhibitory effects on PMN function. We hypothesized that HS could inhibit transepithelial migration of PMN and thereby prevent inflammatory events in experimental colitis. Isolated human PMN were treated with HS (40 mM), and their transmigration across a monolayer of T84 epithelial cells was induced by N-formyl-methionyl-leucyl-phenylalanine. Monolayer disruption was assessed by monitoring changes in transepithelial conductance in an Ussing chamber. Colitis in mice was induced by oral administration of dextran sulfate sodium (DSS). Animals were treated with 4 or 8 ml/kg of 7.5% saline intraperitoneally two times daily for 7 days. Controls received equivalent volumes of normal saline (NS, n = 6) or no intraperitoneal treatment (DSS, n = 12). The severity of inflammation was evaluated based on disease activity index and histology score. HS treatment of PMN in vitro significantly reduced cell migration and the disruption of T84 monolayers compared with untreated control cells (n = 5, P < 0.05). This effect of HS was dose dependent. HS treatment in vivo also reduced colitis-induced gut tissue damage, as indicated by an improved histology score compared with the NS and DSS groups. We conclude that HS inhibits transepithelial migration of PMN in vitro and gut tissue damage in vivo in a mouse model of colitis. Thus HS may have clinical value to reduce PMN-mediated intestinal damage.

Sodium lactate versus mannitol in the treatment of intracranial hypertensive episodes in severe traumatic brain-injured patients

OBJECTIVES

Traumatic brain injury (TBI) is still a major cause of mortality and morbidity. Recent trials have failed to demonstrate a beneficial outcome from therapeutic treatments such as corticosteroids, hypothermia and hypertonic saline. We investigated the effect of a new hyperosmolar solution based on sodium lactate in controlling raised intracranial pressure (ICP).

DESIGN AND SETTING

Prospective open randomized study in an adult ICU.

PATIENTS

Thirty-four patients with isolated severe TBI (Glasgow Coma Scale <or= 8) and intracranial hypertension were allocated to receive equally hyperosmolar and isovolumic therapy, consisting of either mannitol or sodium lactate. Rescue therapy by crossover to the alternative treatment was indicated when ICP could not be controlled. The primary endpoint was efficacy in lowering ICP after 4 h, with a secondary endpoint of the percentage of successfully treated episodes of intracranial hypertension. The analysis was performed with both intention-to-treat and actual treatments provided.

MEASUREMENTS AND RESULTS

Compared to mannitol, the effect of the lactate solution on ICP was significantly more pronounced (7 vs. 4 mmHg, P = 0.016), more prolonged (fourth-hour-ICP decrease: -5.9 +/- 1 vs. -3.2 +/- 0.9 mmHg, P = 0.009) and more frequently successful (90.4 vs. 70.4%, P = 0.053).

CONCLUSION

Acute infusion of a sodium lactate-based hyperosmolar solution is effective in treating intracranial hypertension following traumatic brain injury. This effect is significantly more pronounced than that of an equivalent osmotic load of mannitol. Additionally, in this specific group of patients, long-term outcome was better in terms of GOS in those receiving as compared to mannitol. Larger trials are warranted to confirm our findings.

Moderate and severe traumatic brain injury in adults

Traumatic brain injury (TBI) is a major health and socioeconomic problem that affects all societies. In recent years, patterns of injury have been changing, with more injuries, particularly contusions, occurring in older patients. Blast injuries have been identified as a novel entity with specific characteristics. Traditional approaches to the classification of clinical severity are the subject of debate owing to the widespread policy of early sedation and ventilation in more severely injured patients, and are being supplemented with structural and functional neuroimaging. Basic science research has greatly advanced our knowledge of the mechanisms involved in secondary damage, creating opportunities for medical intervention and targeted therapies; however, translating this research into patient benefit remains a challenge. Clinical management has become much more structured and evidence based since the publication of guidelines covering many aspects of care. In this Review, we summarise new developments and current knowledge and controversies, focusing on moderate and severe TBI in adults. Suggestions are provided for the way forward, with an emphasis on epidemiological monitoring, trauma organisation, and approaches to management.

Management of acute ischemic stroke

Stroke is the third leading cause of death and the leading cause of disability in the United States. This article summarizes the management of acute ischemic stroke, including conventional and novel therapies. The article provides an overview of the initial management, diagnostic work-up, treatment options, and supportive measures that need to be considered in the acute phase of ischemic stroke.

Characterizing the dose-response relationship between mannitol and intracranial pressure in traumatic brain injury patients using a high-frequency physiological data collection system

Despite the widespread use of mannitol to treat elevated intracranial pressure (ICP), there is no consensus regarding the optimal dosage. The objective of this study was to retrospectively characterize the dose-response relationship between mannitol and ICP using data collected with a continuous high-frequency physiological data collection system. To this end, we measured ICP continuously in 28 patients with traumatic brain injury (TBI) who were given at least one dose of mannitol. Twenty TBI patients were given a total of 85 doses of 50 g of mannitol, and 18 patients were given 50 doses of 100 g. Some patients received both amounts. Cerebral perfusion pressure was maintained above 60 mm Hg. The average ICP was 22.0 +/- 10.6 mm Hg when mannitol was administered, fell immediately after dosing, and continued falling for approximately 30 min to 15.7 +/- 8.1 mm Hg across all patients. After 30 min, ICP was equal in the 100-g group (15.6 +/- 10.9) versus the 50-g group (15.7 +/- 6.3). However, at 100 min, ICP had increased in the 50-g group to nearly its initial value but was still lower in the 100-g group (18.6 +/- 7.6 vs. 14.2 +/- 6.7 mm Hg; p = 0.001). Osmotic agents such as mannitol have been used for decades to treat cerebral edema, but there has been no definitive quantitative information regarding the dosing of mannitol. In a large, retrospective study of high-frequency ICP data, we have quantitatively shown that mannitol's effect on ICP is dose-dependent and that higher doses provide a more durable reduction in ICP.

Review article: hypertonic saline use in the emergency department

Hypertonic saline (HS) is being increasingly used for the management of a variety of conditions, most notably raised intracranial pressure. This article reviews the available evidence on HS solutions as they relate to emergency medicine, and develops a set of recommendations for its use. To conclude, HS is recommended as an alternative to mannitol for treating raised intracranial pressure in traumatic brain injury. HS is also recommended for treating severe and symptomatic hyponatremia, and is worth considering for both recalcitrant tricyclic antidepressant toxicity and for cerebral oedema complicating paediatric diabetic ketoacidosis. HS is not recommended for hypovolaemic resuscitation.

Management of intracranial hypertension

Effective management of intracranial hypertension involves meticulous avoidance of factors that precipitate or aggravate increased intracranial pressure. When intracranial pressure becomes elevated, it is important to rule out new mass lesions that should be surgically evacuated. Medical management of increased intracranial pressure should include sedation, drainage of cerebrospinal fluid, and osmotherapy with either mannitol or hypertonic saline. For intracranial hypertension refractory to initial medical management, barbiturate coma, hypothermia, or decompressive craniectomy should be considered. Steroids are not indicated and may be harmful in the treatment of intracranial hypertension resulting from traumatic brain injury.

Hypertonic saline solutions for treatment of intracranial hypertension

PURPOSE OF REVIEW

This review aims to provide an update on recent knowledge gained on hypertonic saline solutions for the treatment of intracranial hypertension. Explanatory approaches to the mechanisms underlying the edema-reducing effects of the solutions are outlined, practical aspects of use are presented, and trials that assessed their clinical utility are highlighted.

RECENT FINDINGS

With an established trauma system, hypertonic saline added to conventional fluid resuscitation did not improve long-term outcome in multiple injury with hypotension and brain trauma. In intensive care, hypertonic saline reduced intracranial hypertension after subarachnoid haemorrhage, brain trauma, and a variety of other brain diseases, including cerebral edema in acute liver failure.

SUMMARY

Hypertonic saline solutions have evolved as an alternative to mannitol or may be used in otherwise refractory intracranial hypertension to treat raised intracranial pressure. With high osmolar loads, the efficacy of the solution is enhanced, but no simple relationship between the saline concentration and the clinical effects of a solution is established. Caution is advised with high osmolar loads because they carry increased risks for potentially deleterious consequences of hypernatremia or may induce osmotic blood-brain barrier opening with possibly harmful extravasation of the hypertonic solution into the brain tissue.

The influence of volume management on outcome

PURPOSE OF REVIEW

Fluid (volume) therapy is an integral component in the management of critically ill patients and fluid management may influence outcome. There is much controversy, however, about the type, timing and amount of fluid therapy. Here, we discuss the evidence available to guide such choices.

RECENT FINDINGS

Fluid therapy is widely endorsed for resuscitation of critically ill patients across a range of conditions. Yet, the approach to fluid therapy is subject to substantial variation in clinical practice. Emerging data show that the choice, timing and amount of fluid therapy may affect clinical outcomes. Synthetic colloids may increase the risk of acute kidney injury. Albumin may benefit hypoalbuminemic patients with sepsis and acute lung injury but may worsen outcome in traumatic brain injury. Early administration of fluid therapy in sepsis may improve survival but may be unnecessary in patients with penetrating trauma. Later fluid therapy in acute lung injury patients will increase the duration of ventilator dependence without achieving better survival. A positive cumulative balance likely contributes to increased morbidity and mortality after major surgery.

SUMMARY

Emerging evidence shows that choice, timing and amount of fluid therapy affect outcome. Future studies need to focus on these aspects of fluid therapy by means of larger, more rigorous and blinded controlled trials.

Resuscitation of Hypotensive Head-Injured Patients: Is Hypertonic Saline the Answer?

Hypertonic saline (HTS) may decrease intracranial pressure (ICP) in severe traumatic brain injury (STBI) and effectively resuscitates hypotensive patients. No data exist on institutional standardization of HTS for hypotensive patients with STBI. It remains unclear how HTS affects brain tissue oxygenation (PbtO2) in STBI. We hypothesized HTS could be safely standardized in patients with STBI and would lower ICP while improving cerebral perfusion pressure (CPP) and PbtO2. Under institutional guidelines in a Level I trauma center, 12 hypotensive STBI intensive care unit subjects received HTS. Inclusion criteria included mean arterial pressure (MAP) ≤ 90 mmHg, Glasgow Coma Scale (GCS) ≤ 8, ICP ≥ 20 mmHg, and serum [Na+] < 155 mEq/L. All patients underwent ICP monitoring. Hemodynamics, CPP, ICP, and PbtO2 data were collected before and hourly for 6 hours after HTS infusion. Guideline criteria compliance was greater than 95 per cent. No major complications occurred. Mean ICP levels dropped by 45 per cent (P < 0.01) and this drop persisted for 6 hours. CPP levels increased by 20 per cent (P < 0.05). PbtO2 remained persistently elevated for all time points after HTS infusion. Institutional use of HTS in STBI can be safely implemented in a center caring for neurotrauma patients. HTS infusion in hypotensive STBI reduces ICP and raises CPP. Brain tissue oxygenation tends to improve after HTS infusion.

Intensive care of patients with acute liver failure: recommendations of the U.S. Acute Liver Failure Study Group

OBJECTIVE

To provide a uniform platform from which to study acute liver failure, the U.S. Acute Liver Failure Study Group has sought to standardize the management of patients with acute liver failure within participating centers.

METHODS

In areas where consensus could not be reached because of divergent practices and a paucity of studies in acute liver failure patients, additional information was gleaned from the intensive care literature and literature on the management of intracranial hypertension in non-acute liver failure patients. Experts in diverse fields were included in the development of a standard study-wide management protocol.

MEASUREMENTS AND MAIN RESULTS

Intracranial pressure monitoring is recommended in patients with advanced hepatic encephalopathy who are awaiting orthotopic liver transplantation. At an intracranial pressure of > or =25 mm Hg, osmotic therapy should be instituted with intravenous mannitol boluses. Patients with acute liver failure should be maintained in a mildly hyperosmotic state to minimize cerebral edema. Accordingly, serum sodium should be maintained at least within high normal limits, but hypertonic saline administered to 145-155 mmol/L may be considered in patients with intracranial hypertension refractory to mannitol. Data are insufficient to recommend further therapy in patients who fail osmotherapy, although the induction of moderate hypothermia appears to be promising as a bridge to orthotopic liver transplantation. Empirical broad-spectrum antibiotics should be administered to any patient with acute liver failure who develops signs of the systemic inflammatory response syndrome, or unexplained progression to higher grades of encephalopathy. Other recommendations encompassing specific hematologic, renal, pulmonary, and endocrine complications of acute liver failure patients are provided, including their management during and after orthotopic liver transplantation.

CONCLUSIONS

The present consensus details the intensive care management of patients with acute liver failure. Such guidelines may be useful not only for the management of individual patients with acute liver failure, but also to improve the uniformity of practices across academic centers for the purpose of collaborative studies.

Advanced Trauma Life Support (ATLS) and facial trauma: can one size fit all? Part 3: Hypovolaemia and facial injuries in the multiply injured patient

Hypovolaemic shock is a common cause of morbidity and mortality following trauma, accounting for approximately 30% to 40% of trauma deaths. Life-threatening blood loss from the maxillofacial region is uncommon, but represents one of a number of possible sites which must be rapidly identified and controlled. Bleeding from the face may not be obvious especially in awake, supine patients and it poses an obvious threat to the unprotected airway. Identification requires careful assessment. Control of bleeding in the maxillofacial region requires a number of correctly sequenced techniques. Computerized tomographic imaging is now playing an increasingly important role in identifying blood loss, especially in the chest, abdomen and pelvis. This need may potentially result in the transfer of patients, with unrecognised facial injuries, outside the relative safety of the emergency department. The concepts of the 'lethal triad' and 'biologic first hit' have resulted in new strategies in managing the profoundly shocked patient, although some of these remain controversial. Debate continues over the optimal blood pressure, fluid administration and role of surgical intervention in the actively bleeding patient. These may have an impact on the timing and extent of any proposed maxillofacial repairs, and are discussed.

Dose-response relationship of mannitol and intracranial pressure: a metaanalysis

OBJECTIVE

Brain edema can increase intracranial pressure (ICP), potentially leading to ischemia, herniation, and death. Edema and elevated ICP are often treated with osmotic agents to remove water from brain tissue. Mannitol is the osmotic diuretic most commonly used in the intensive care unit; however, despite its clinical importance, treatment protocols vary from center to center, and the dose-response relationship is not understood. The goal of this metaanalysis was to aggregate and analyze data from studies in which authors have described the dose-response relationship between mannitol and ICP.

METHODS

The authors identified 18 studies that quantitatively characterized the dose-response relationship of mannitol and ICP. We also examined study designs and mannitol administration protocols.

RESULTS

Meta-regression found a weak linear relationship between change in ICP (delta ICP) and dose (delta ICP = 6.6 x dose - 1.1; p = 0.27, R(2) = 0.05). The lack of statistical significance could reflect the variation in protocols among studies and the variation in patients both within and among studies. However, the authors found a highly significant difference (p < 0.001) in decrease in ICP when the initial ICP was higher or lower than 30 mm Hg. Nonlinear regression suggested that ICP decrease is greatest shortly after mannitol is given (R(2) = 0.63). Finally, the authors found that recent studies tend to include fewer patients and set a lower ICP threshold for mannitol administration but report more parameters of interest; the duration of mannitol's effect was the most frequently unreported parameter.

CONCLUSIONS

Despite its clinical importance, the determination of the mannitol dose-response curve continues to be challenging for many reasons. This metaanalysis highlights the need for a consensus of methods and results required to determine this important relationship.

Hyponatremia treatment guidelines 2007: expert panel recommendations

Although hyponatremia is a common, usually mild, and relatively asymptomatic disorder of electrolytes, acute severe hyponatremia can cause substantial morbidity and mortality, particularly in patients with concomitant disease. In addition, overly rapid correction of chronic hyponatremia can cause severe neurologic deficits and death, and optimal treatment strategies for such cases are not established. An expert panel assessed the potential contributions of aquaretic nonpeptide small-molecule arginine vasopressin receptor (AVPR) antagonists to hyponatremia therapies. This review presents their conclusions, including identification of appropriate treatment populations and possible future indications for aquaretic AVPR antagonists.

Survey of management of severe head injury in Canada

OBJECTIVE

To determine: 1. the degrees of consensus and disagreement among Canadian critical care clinicians regarding the appropriateness (benefit exceeding risk) of common therapeutic manoeuvres in patients with severe closed head injury (CHI), and 2. the frequency with which clinicians employed these manoeuvres.

METHODS

The study design was a systematic scenario-based survey of all neurosurgeons and critical care physicians treating patients with severe CHI in Canada.

RESULTS

In the scenario of acute epidural hematoma with mass effect, respondents agreed very strongly that surgery was appropriate. Clinicians reported mannitol and hypertonic saline as appropriate. Beyond these two interventions, agreement was less strong, and the use of the extraventricular drain (EVD), phenytoin, cooling, hyperventilation, nimodipine, and jugular venous oximetry (JVO) were of uncertain appropriateness. Steroids were considered inappropriate. In a scenario of diffuse axonal injury (DAI), clinicians agreed strongly that fever reduction, early enteral feeding, intensive glucose control, and cerebral perfusion pressure (CPP)-directed management were appropriate. The use of mannitol, hypertonic saline, EVD, JVO, narcotics and propofol were also appropriate. Neuromuscular blockade, surgery, and hyperventilation were of uncertain appropriateness. The appropriateness ratings of the interventions considered in the scenario of an intracranial contusion mirrored the DAI scenario. In general, correlations between the reported appropriateness and frequency of use of each intervention were very high. An exception noted was the use of the JVO. The correlation between CPP-guided therapy and the use of the EVD was weak.

CONCLUSIONS

This survey has described current practice with regard to treatment of patients with severe CHI. Areas of variation in perceived appropriateness were identified that may benefit from further evaluation. Suggested priorities for evaluation include the use of osmotic diuretics, anticonvulsants, and intracranial manometry.

Traumatic brain injury in horses: 34 cases (1994-2004)

OBJECTIVE

To investigate the clinical, clinicopathologic, and diagnostic characteristics; treatment; and outcome associated with acute traumatic brain injury (TBI) in horses and assess risk factors for nonsurvival in TBI-affected horses.

DESIGN

Retrospective case series.

ANIMALS

34 horses with TBI. Procedures-Medical records of horses that had sustained trauma to the head and developed neurologic signs were reviewed. Data that included signalment, clinicopathologic findings, diagnosis, treatment, and outcome were analyzed. Clinicopathologic variables among horses in survivor and nonsurvivor groups were compared, and risk factors for nonsurvival were determined.

RESULTS

Median age of affected horses was 12 months. Findings of conventional survey radiography of the head alone failed to identify all horses with fractures of the calvarium. Horses with basilar bone fractures were 7.5 times as likely not to survive as horses without this type of fracture. Depending on clinical signs, horses received supportive care, osmotic or diuretic treatments, antimicrobials, anti-inflammatory drugs, analgesics, or anticonvulsants. Twenty-one (62%) horses survived to discharge from the hospital. In the nonsurvivor group, mean PCV was significantly higher, compared with the value in the survivor group (40% vs 33%). Risk factors associated with nonsurvival included recumbency of more than 4 hours' duration after initial evaluation (odds ratio, 18) and fracture of the basilar bone (odds ratio, 7.5).

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that prognosis for survival in horses with acute TBI may be more favorable than previously reported. Among horses with TBI, persistent recumbency and fractures involving the basilar bones were associated with a poor prognosis.

Use of Nuclear Magnetic Resonance Spectroscopy to Assess Renal Dysfunction After Hypertonic-Hyperoncotic Resuscitation in Rats

BACKGROUND

The aim of this study was to evaluate the renal tolerance of a hypertonic-hyperoncotic solution (HHS) administration during uncontrolled hemorrhagic shock (UHS).

METHODS

UHS was produced in rats by a preliminary bleed followed by tail amputation. Hydroxyethylstarch (HHS) 200/0.5 6% in NaCl 7.2% was administered to the HHS groups (n = 20) and normal saline (NS) to the NS group (n = 20). Infusion rates were adjusted to prevent mean arterial pressure (MAP) from falling either below 40 mm Hg in the HHS40 (n = 10) and NS40 groups (n = 10), or below 80 mm Hg in the HHS80 (n = 10) and NS80 groups (n = 10). Data obtained were compared with a sham group and a no resuscitation (NR) group. Nephrotoxicity was evaluated by nuclear magnetic resonance analysis in urine samples.

RESULTS

Survival was 60% in the NS40 group and 40% in the NS80 group, 70% in the HHS40 group, and 60% in the HHS80 group (p = not significant). Within and between target groups of 40 mm Hg MAP and 80 mm Hg MAP, there was no significant difference in survival. The mean values of renal metabolites to creatinine (ct) ratios were not significantly different among the six groups. Principal component analysis showed that the HHS80 group was characterized by an increase in allantoin/ct and urea/ct ratios demonstrating acute renal dysfunction and failure of nitrogen metabolism.

CONCLUSION

In prolonged UHS, an infusion of HHS may not increase the rate of survival. HHS infusion in normotensive resuscitation appears to be associated with renal toxicity.

Mannitol for acute stroke

BACKGROUND

Mannitol is an osmotic agent and a free radical scavenger which might decrease oedema and tissue damage in stroke.

OBJECTIVES

To test whether treatment with mannitol reduces short and long-term case fatality and dependency after acute ischaemic stroke or intracerebral haemorrhage (ICH).

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (searched December 2006), MEDLINE (1966 to January 2007), the Chinese Stroke Trials Register (searched November 2006), the China Biological Medicine Database (searched December 2006) and the Latin-American database LILACS (1982 to December 2006). We also searched the database of Masters and PhD degree theses at Sao Paulo University (searched January 2007), and neurology and neurosurgery conference proceedings in Brazil from 1965 to 2006. In an effort to identify further published, ongoing and unpublished studies we searched reference lists and contacted authors of published trials.

SELECTION CRITERIA

We included randomised controlled trials comparing mannitol with placebo or open control in patients with acute ischaemic stroke or non-traumatic intracerebral haemorrhage.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials, assessed quality, extracted data, and performed the data analysis.

MAIN RESULTS

Three small trials, involving 226 participants, were included. One trial included patients with presumed ischaemic stroke without computerised tomography (CT) verification, and the other two trials included patients with CT-verified ICH. Data on the primary outcome measure (death and dependency) were not available in any of the trials. Death and disability could be calculated in the larger ICH trial without differences between the mannitol and control groups. Case fatality was not reported in the trial of ischaemic stroke. Case fatality did not differ between the mannitol and control groups in the ICH trials. Adverse events were either not found or not reported. The change in clinical condition was reported in two trials, and the proportion of those with worsening or not improving condition did not differ significantly between mannitol-treated patients and controls. Based on these three trials neither beneficial nor harmful effects of mannitol could be proved. Although no statistically significant differences were found between the mannitol-treated and control groups, the confidence intervals for the treatment effect estimates were wide and included both clinically significant benefits and clinically significant harms as possibilities.

AUTHORS' CONCLUSIONS

There is currently not enough evidence to support the routine use of mannitol in acute stroke patients. Further trials are needed to confirm or refute whether mannitol is beneficial in acute stroke.

Hypertonic saline: first-line therapy for cerebral edema?

This article highlights the experimental and clinical data, controversies and postulated mechanisms surrounding osmotherapy with hypertonic saline (HS) solutions in the neurocritical care arena and builds on previous reviews on the subject. Special attention is focused on HS therapy on commonly encountered clinical paradigms of acute brain injury including traumatic brain injury (TBI), post-operative "retraction edema", intracranial hemorrhage (ICH), tumor-associated cerebral edema, and ischemia associated with ischemic stroke.