Prophylactic hyperdynamic postoperative fluid therapy after aneurysmal subarachnoid hemorrhage: a clinical, prospective, randomized, controlled study

Triggers for aggressive interventions in subarachnoid hemorrhage

Ischemia is a common cause of secondary neuronal injury after aneurysmal subarachnoid hemorrhage. An electronic literature search was conducted to identify clinical signs and laboratory data that could serve as predictors for delayed cerebral ischemia and define triggers for additional diagnostic testing or more aggressive intervention. Fifteen articles describing original research that included some discussion of triggers were identified and reviewed. Quality of evidence was considered very low to moderate for included studies. Using data from these studies and expert opinion, a variety of clinical signs and monitoring data were identified as potentially useful triggers for additional tests or aggressive treatments. These data were used to develop a sequence that might be employed in the clinical management of subarachnoid hemorrhage to determine which patients need additional attention, testing, or interventions to reduce/prevent ischemia caused by vasospasm.

Hemodynamic management of subarachnoid hemorrhage

Hemodynamic augmentation therapy is considered standard treatment to help prevent and treat vasospasm and delayed cerebral ischemia. Standard triple-H therapy combines volume expansion (hypervolemia), blood pressure augmentation (hypertension), and hemodilution. An electronic literature search was conducted of English-language papers published between 2000 and October 2010 that focused on hemodynamic augmentation therapies in patients with subarachnoid hemorrhage. Among the eligible reports identified, 11 addressed volume expansion, 10 blood pressure management, 4 inotropic therapy, and 12 hemodynamic augmentation in patients with unsecured aneurysms. While hypovolemia should be avoided, hypervolemia did not appear to confer additional benefits over normovolemic therapy, with an excess of side effects occurring in patients treated with hypervolemic targets. Overall, hypertension was associated with higher cerebral blood flow, regardless of volume status (normo- or hypervolemia), with neurological symptom reversal seen in two-thirds of treated patients. Limited data were available for evaluating inotropic agents or hemodynamic augmentation in patients with additional unsecured aneurysms. In the context of sparse data, no incremental risk of aneurysmal rupture has been reported with the induction of hemodynamic augmentation.

Critical care guidelines on the endovascular management of cerebral vasospasm

Cerebral vasospasm and delayed cerebral ischemia account for significant morbidity and mortality after aneurysmal subarachnoid hemorrhage. While most patients are managed with triple-H therapy, endovascular treatments have been used when triple-H treatment cannot be used or is ineffective. An electronic literature search was conducted to identify English language articles published through October 2010 that addressed endovascular management of vasospasm. A total of 49 articles were identified, addressing endovascular treatment timing, intra-arterial treatments, and balloon angioplasty. Most of the available studies investigated intra-arterial papaverine or balloon angioplasty. Both have generally been shown to successfully treat vasospasm and improve neurological condition, with no clear benefit from one treatment compared with another. There are reports of complications with both therapies including vessel rupture during angioplasty, intracranial hypertension, and possible neurotoxicity associated with papaverine. Limited data are available evaluating nicardipine or verapamil, with positive benefits reported with nicardipine and inconsistent benefits with verapamil.

Routine management of volume status after aneurysmal subarachnoid hemorrhage

Prophylactic use of hypervolemia and hypertension is believed to present an option to decrease the incidence of symptomatic vasospasm after aneurysmal subarachnoid hemorrhage and improve neurologic outcome. A Medline literature search was conducted to review available evidence regarding volume management after subarachnoid hemorrhage. Quality of selected studies was evaluated, using the standardized GRADE system. Eleven studies focused on prophylactic hypervolemic therapy after aneurysmal subarachnoid hemorrhage were identified, including four randomized controlled trials. Available studies showed a large heterogeneity in physiologic treatment goals and interventions applied. The oldest and smallest randomized controlled trial suggested a positive effect, but had severe limitations in trial design. Neither of the other randomized controlled studies showed outcome benefit with hypervolemic therapy. Results from observational studies were not found to support the use of prophylactic hypervolemia and hypertension. Complication frequency was repeatedly reported to be higher with the application of prophylactic hypervolemia. In summary, prophylactic hyperdynamic therapy after subarachnoid hemorrhage has not been adequately shown to effectively raise cerebral blood flow or improve neurological outcome. In contrast, there is evidence for harm using overly aggressive hydration.

Role of calcitonin gene-related peptide in cerebral vasospasm, and as a therapeutic approach to subarachnoid hemorrhage

Calcitonin gene-related peptide (CGRP) is one of the most potent microvascular vasodilators identified to date. Vascular relaxation and vasodilation is mediated via activation of the CGRP receptor. This atypical receptor is made up of a G protein-coupled receptor called calcitonin receptor-like receptor (CLR), a single transmembrane protein called receptor activity-modifying protein (RAMP), and an additional protein that is required for Ga(s) coupling, known as receptor component protein (RCP). Several mechanisms involved in CGRP-mediated relaxation have been identified. These include nitric oxide (NO)-dependent endothelium-dependent mechanisms or cAMP-mediated endothelium-independent pathways; the latter being more common. Subarachnoid hemorrhage (SAH) is associated with cerebral vasoconstriction that occurs several days after the hemorrhage and is often fatal. The vasospasm occurs in 30-40% of patients and is the major cause of death from this condition. The vasoconstriction is associated with a decrease in CGRP levels in nerves and an increase in CGRP levels in draining blood, suggesting that CGRP is released from nerves to oppose the vasoconstriction. This evidence has led to the concept that exogenous CGRP may be beneficial in a condition that has proven hard to treat. The present article reviews: (a) the pathophysiology of delayed ischemic neurologic deficit after SAH (b) the basics of the CGRP receptor structure, signal transduction, and vasodilatation mechanisms and (c) the studies that have been conducted so far using CGRP in both animals and humans with SAH.

Treatment options for cerebral vasospasm in aneurysmal subarachnoid hemorrhage

Cerebral vasospasm occurs frequently after aneurysmal subarachnoid and contributes to delayed cerebral ischemia. In this article we address systematic problems with the literature on vasospasm and then review both established and experimental treatment options.

Comparison of induced hypertension, fluid bolus, and blood transfusion to augment cerebral oxygen delivery after subarachnoid hemorrhage

OBJECT

Critical reductions in oxygen delivery (DO(2)) underlie the development of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH). If DO(2) is not promptly restored, then irreversible injury (that is, cerebral infarction) may result. Hemodynamic therapies for DCI (that is, induced hypertension [IH] and hypervolemia) aim to improve DO(2) by raising cerebral blood flow (CBF). Red blood cell (RBC) transfusion may be an alternate strategy that augments DO(2) by improving arterial O(2) content. The authors compared the relative ability of these 3 interventions to improve cerebral DO(2), specifically their ability to restore DO(2) to regions where it is impaired.

METHODS

The authors compared 3 prospective physiological studies in which PET imaging was used to measure global and regional CBF and DO(2) before and after the following treatments: 1) fluid bolus of 15 ml/kg normal saline (9 patients); 2) raising mean arterial pressure 25% (12 patients); and 3) transfusing 1 U of RBCs (17 patients) in 38 individuals with aneurysmal SAH at risk for DCI. Response between groups in regions with low DO(2) (< 4.5 ml/100 g/min) was compared using repeated-measures ANOVA.

RESULTS

Groups were similar except that the fluid bolus cohort had more patients with symptoms of DCI and lower baseline CBF. Global CBF or DO(2) did not rise significantly after any of the interventions, except after transfusion in patients with hemoglobin levels < 9 g/dl. All 3 treatments improved CBF and DO(2) to regions with impaired baseline DO(2), with a greater improvement after transfusion (23%) than hypertension (14%) or volume loading (10%); p < 0.001. Transfusion also resulted in a nonsignificantly greater (47%) reduction in the number of brain regions with low DO(2) when compared with fluid bolus (7%) and hypertension (12%) (p = 0.33).

CONCLUSIONS

The IH, fluid bolus, and blood transfusion interventions all improve DO(2) to vulnerable brain regions at risk for ischemia after SAH. Transfusion appeared to provide a physiological benefit at least comparable to IH, especially among patients with anemia, but transfusion is associated with risks. The clinical significance of these findings remains to be established in controlled clinical trials.

Current practices of triple-H prophylaxis and therapy in patients with subarachnoid hemorrhage

BACKGROUND

Medical management of cerebral vasospasm following aneurysmal subarachnoid hemorrhage (SAH) includes hypertensive, hypervolemic, and hemodilution ("triple-H") therapy. However, there is little information regarding the indications and guidance used to initiate and adjust triple-H therapy.

METHODS

A 43-item questionnaire was e-mailed to 375 members of the Neurocritical Care Society. Questions were designed to investigate the diagnostic approach to cerebral vasospasm and prophylactic and therapeutic administration of triple-H therapy.

RESULTS

Completed surveys were received from 167 respondents (45% response proportion). Eighty-six percent of respondents worked in hospitals with neurointensive care units (NICUs). SAH patients in hospitals with a NICU had longer ICU stay (P = 0.037) and had indwelling central venous catheters for longer (P < 0.01). Centers without dedicated NICUs were more likely to induce prophylactic hypervolemia (P < 0.01). Twenty seven percent of respondents (n = 45) reported using prophylactic hypervolemia in patients with SAH, while 100% reported inducing hypervolemia for severe or symptomatic vasospasm. Twelve percent (n = 20) of respondents reported inducing prophylactic hypertension, while all reported inducing hypertension with severe or symptomatic vasospasm. Half of respondents relied on the mean arterial pressure and half on systolic blood pressure as the clinical parameter for blood pressure titration. The most widely used agents to induce hypertension were phenylephrine (48%) and norepinephrine (39%). There was little variation in the use of hemodilution therapy comparing patients with or without evidence of vasospasm.

CONCLUSIONS

There are substantial differences in the administration of prophylactic triple-H, but there was high agreement on indication for therapeutic use. There was wide variability in the extent of ICU monitoring, diagnostic approach, physiologic parameters and values used as target of therapy. NICU availability was associated with more intensive monitoring. Lack of evidence and guidelines for triple-H therapy might largely explain these findings.

Preventing vasospasm improves outcome after aneurysmal subarachnoid hemorrhage: rationale and design of CONSCIOUS-2 and CONSCIOUS-3 trials

Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (aSAH) is a frequent but unpredictable complication associated with poor outcome. Current vasospasm therapies are suboptimal; new therapies are needed. Clazosentan, an endothelin receptor antagonist, has shown promise in phase 2 studies, and two randomized, double-blind, placebo-controlled phase 3 trials (CONSCIOUS-2 and CONSCIOUS-3) are underway to further investigate its impact on vasospasm-related outcome after aSAH. Here, we describe the design of these studies, which was challenging with respect to defining endpoints and standardizing endpoint interpretation and patient care. Main inclusion criteria are: age 18-75 years; SAH due to ruptured saccular aneurysm secured by surgical clipping (CONSCIOUS-2) or endovascular coiling (CONSCIOUS-3); substantial subarachnoid clot; and World Federation of Neurosurgical Societies grades I-IV prior to aneurysm-securing procedure. In CONSCIOUS-2, patients are randomized 2:1 to clazosentan (5 mg/h) or placebo. In CONSCIOUS-3, patients are randomized 1:1:1 to clazosentan 5, 15 mg/h, or placebo. Treatment is initiated within 56 h of aSAH and continued until 14 days after aSAH. Primary endpoint is a composite of mortality and vasospasm-related morbidity within 6 weeks of aSAH (all-cause mortality, vasospasm-related new cerebral infarction, vasospasm-related delayed ischemic neurological deficit, neurological signs or symptoms in the presence of angiographic vasospasm leading to rescue therapy initiation). Main secondary endpoint is extended Glasgow Outcome Scale at week 12. A critical events committee assesses all data centrally to ensure consistency in interpretation, and patient management guidelines are used to standardize care. Results are expected at the end of 2010 and 2011 for CONSCIOUS-2 and CONSCIOUS-3, respectively.

Treatment of subarachnoid hemorrhage with human albumin: ALISAH study. Rationale and design

The primary objective of this prospective dose-finding pilot study is to demonstrate the tolerability and safety of four dosages of 25% human albumin in patients with subarachnoid hemorrhage (SAH). For each dosage group, the study will enroll 20 patients who meet the eligibility criteria. The enrolled patients will undergo follow-up for 90 days post-treatment. The primary tolerability hypothesis is that intravenous 25% human albumin can be given without precipitating treatment related serious adverse events beyond expectations. The study will determine the maximum tolerated dosage of 25% human albumin therapy based on the rate of treatment related serious adverse events during treatment: severe or life-threatening heart failure. The secondary objectives are to obtain preliminary estimates of the albumin treatment effect using the incidence of neurological deterioration within 15 days after symptom onset. In addition, the incidence of rebleeding, hydrocephalus, seizures, delayed cerebral ischemia and the incidence of vasospasm (both symptomatic and by transcranial Doppler ultrasound criteria) within 15 days after symptom onset will be evaluated. Furthermore, the serum osmolality and serum albumin concentrations, serum magnesium concentration, blood pressure and heart rate within 15 days of symptom onset will also be observed. The Glasgow Outcome Scale, Barthel Index, modified Rankin Scale, NIH Stroke Scale, and Stroke Impact Scale will be performed 3 months after the onset of symptoms to assess residual neurological deficits.

Spreading depolarization: a possible new culprit in the delayed cerebral ischemia of subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (SAH) is a devastating disease with a high mortality and morbidity rate. Gradual improvements have been made in the reduction of mortality rates associated with the disease during the last 30 years. However, delayed cerebral ischemia (DCI), the major delayed complication of SAH, remains a significant contributor to mortality and morbidity despite substantial research and clinical efforts. During the last several years, the predominant role of cerebral vasospasm, the long-accepted etiologic factor behind DCI, has been questioned. It is now becoming increasingly clear that the pathophysiology underlying DCI is multifactorial. Cortical spreading depression is emerging as a likely factor in this complex web of pathologic changes after SAH. Understanding its role after SAH and its relationship with the other pathologic processes such as vasospasm, microcirculatory dysfunction, and microemboli will be vital to the development of new therapeutic approaches to reduce DCI and improve the clinical outcome of the disease.

Early surgery of multiple versus single aneurysms after subarachnoid hemorrhage: an increased risk for cerebral vasospasm?

OBJECT

As many as 33% of patients suffering from subarachnoid hemorrhage (SAH) present with multiple intracranial aneurysms (MIAs). It is believed that aneurysm surgery has the potential to increase the risk of cerebral vasospasm due to surgical manipulations of the parent vessels and brain tissue. Consequently, 1-stage surgery of MIAs, which usually takes longer and requires more manipulation, could even further increase the risk of vasospasm. The aim of this study is to define the correlation between vasospasm and the operative treatment of single intracranial aneurysms versus MIAs in a 1-stage operation.

METHODS

The authors analyzed a database including 1016 patients with SAH, identified retrospectively between 1989 and 1996 and prospectively collected between 1997 and 2004. Exclusion criteria were endovascular treatment, surgery after SAH Day 3, and, in patients with MIAs, undergoing more than 1 operation. Cerebral vasospasm was diagnosed by transcranial Doppler (TCD) ultrasonography and was defined as a maximum mean blood flow velocity > 120 cm/second. The diagnosis of symptomatic vasospasm was made if a new neurological deficit occurred that could not be explained by concomitant complications.

RESULTS

A total of 643 patients who experienced 810 aneurysms were included. Four hundred twenty-four patients were female (65.9%) and 219 were male (34.1%) with an average age of 53.1 years. One hundred twenty-one patients (18.8%) were diagnosed with MIAs. Maximum mean flow velocities measured by TCD were 131 cm/second in patients with MIAs and 129.5 cm/second in patients with single intracranial aneurysms. The incidence of TCD vasospasm (p = 0.561) as well as of symptomatic vasospasm (p = 0.241) was not significantly different in the 2 groups.

CONCLUSIONS

Clipping of more than 1 aneurysm in a 1-stage operation within 72 hours after SAH can be performed without increasing the risk of cerebral (TCD) vasospasm and symptomatic vasospasm.

Effect of different components of triple-H therapy on cerebral perfusion in patients with aneurysmal subarachnoid haemorrhage: a systematic review

Introduction

Triple-H therapy and its separate components (hypervolemia, hemodilution, and hypertension) aim to increase cerebral perfusion in subarachnoid haemorrhage (SAH) patients with delayed cerebral ischemia. We systematically reviewed the literature on the effect of triple-H components on cerebral perfusion in SAH patients.

Methods

We searched medical databases to identify all articles until October 2009 (except case reports) on treatment with triple-H components in SAH patients with evaluation of the treatment using cerebral blood flow (CBF in ml/100 g/min) measurement. We summarized study design, patient and intervention characteristics, and calculated differences in mean CBF before and after intervention.

Results

Eleven studies (4 to 51 patients per study) were included (one randomized trial). Hemodilution did not change CBF. One of seven studies on hypervolemia showed statistically significant CBF increase compared to baseline; there was no comparable control group. Two of four studies applying hypertension and one of two applying triple-H showed significant CBF increase, none used a control group. The large heterogeneity in interventions and study populations prohibited meta-analyses.

Conclusions

There is no good evidence from controlled studies for a positive effect of triple-H or its separate components on CBF in SAH patients. In uncontrolled studies, hypertension seems to be more effective in increasing CBF than hemodilution or hypervolemia.

Blood volume measurement with indocyanine green pulse spectrophotometry: dose and site of dye administration

Background

(1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of this technique in patients who were treated for an intracranial aneurysm.

Methods

Four repeated measurements of blood volume (BV) were performed in random order of bolus dose (10 mg or 25 mg ICG) and venous administration site (peripheral or central) in eight patients admitted for treatment of an intracranial aneurysm. Another five patients with subarachnoid hemorrhage underwent three repeated BV measurements with 25 mg ICG at the same administration site to assess the coefficient of variation.

Findings

The mean ± SD in BV was 4.38 ± 0.88 l (n = 25) and 4.69 ± 1.11 l (n = 26) for 10 mg and 25 mg ICG, respectively. The mean ± SD in BV was 4.59 ± 1.15 l (n = 26) and 4.48 ± 0.86 l (n = 25) for central and peripheral administration, respectively. No significant difference was found. The coefficient of variance of BV measurement with 25 mg of ICG was 7.5% (95% CI: 3–12%).

Conclusions

There is no significant difference between intravenous administration of either 10 or 25 mg ICG, and this can be injected through either a peripheral or central venous catheter. The 7.5% coefficient of variation in BV measurements determines the detectable differences using ICG pulse spectrophotometry.

Role of vasopressor administration in patients with acute neurologic injury

INTRODUCTION

Pharmacologic blood pressure elevation is often utilized to prevent or treat ischemia in patients with acute neurologic injury, and routinely requires administration of vasopressor agents. Depending on the indication, vasopressor agents may be administered to treat hypotension or to induce hypertension.

METHODS

Although numerous guideline statements exist regarding the management of blood pressure in these patients, most recommendations are based largely on Class III evidence. Further, there are few randomized controlled trials comparing vasopressor agents in these patients and selection is often guided by expert consensus.

RESULTS

We discuss the clinical evidence regarding vasopressor administration for blood pressure management in patients with acute neurologic injury. The effect of various vasopressors on cerebral hemodynamics is also discussed.

CONCLUSION

Although high-quality clinical data are scarce, the available evidence suggests that norepinephrine should be considered as the vasopressor of choice when blood pressure elevation is indicated in patients with acute neurologic injury.

The impact of a highly visible display of cerebral perfusion pressure on outcome in individuals with cerebral aneurysms

BACKGROUND

Nurses' ability to rapidly detect decreases in cerebral perfusion pressure (CPP), which may contribute to secondary brain injury, may be limited by poor visibility of CPP displays.

OBJECTIVE

To evaluate the impact of a highly visible CPP display on the functional outcome in individuals with cerebral aneurysms.

METHODS

Patients with cerebral aneurysms (n = 100) who underwent continuous CPP monitoring were enrolled and randomized to beds with or without the additional CPP display. Six-month outcome was assessed.

RESULTS

Functional outcome was not significantly different between control and intervention groups after controlling for initial neurologic condition (odds ratio .904, 95% confidence interval 0.317 to 2.573). However, greater time below CPP thresholds (55 to 70 mm Hg) was significantly associated with poorer outcome (P = .005 to .010).

CONCLUSIONS

Although the enhanced CPP display was not associated with significantly better outcome, longer periods of CPP below set levels were associated with poorer outcome.

Arginine vasopressin as a supplementary vasopressor in refractory hypertensive, hypervolemic, hemodilutional therapy in subarachnoid hemorrhage

INTRODUCTION

Hypertensive, hypervolemic, and hemodilutional (HHH) therapy for vasospasm in subarachnoid hemorrhage (SAH) refractory to phenylephrine requires high doses of catecholamines, leading to adverse adrenergic effects. Arginine vasopressin (AVP) has been shown to stabilize advanced shock states while facilitating reduction of catecholamine doses, but its use has never been reported in SAH. In this retrospective study, we investigated the hemodynamic effects and feasibility of supplementary AVP in refractory HHH therapy in SAH.

METHODS

Hemodynamic response (mean arterial pressure [MAP], heart rate, central venous pressure, cardiac index, systemic vascular resistance index, and end diastolic volume index) to a supplementary AVP infusion (0.01-0.04 IU/minute) was recorded within the first 24 hours in 22 patients. Secondary endpoints (serum sodium concentration, incidence of vasospasm, and intracranial pressure [ICP]) were compared to controls on HHH therapy with phenylephrine alone.

RESULTS

After initiation of AVP, MAP increased significantly compared to baseline. Phenylephrine doses decreased significantly, whereas other hemodynamic parameters remained stable. Serum sodium concentrations decreased similarly in both groups (-5 +/- 7 mmol/L versus -6 +/- 4 mmol/L; p = 0.25). No detrimental effects on vasospasm incidence or ICP and cerebral perfusion pressure were noted.

CONCLUSION

AVP may be considered as an alternative supplementary vasopressor in refractory HHH therapy with phenylephrine in SAH. Although we did not observe any deleterious effect of AVP on cerebral circulation, close observation for development of cerebral vasospasm should be undertaken, until it is clearly demonstrated that AVP has no adverse effects on regional cerebral blood flow and symptomatic cerebral vasospasm. Our limited data suggest that low-dose AVP does not cause brain edema, but further study is merited.

Clinical review: Prevention and therapy of vasospasm in subarachnoid hemorrhage

Vasospasm is one of the leading causes of morbidity and mortality following aneurysmal subarachnoid hemorrhage (SAH). Radiographic vasospasm usually develops between 5 and 15 days after the initial hemorrhage, and is associated with clinically apparent delayed ischemic neurological deficits (DID) in one-third of patients. The pathophysiology of this reversible vasculopathy is not fully understood but appears to involve structural changes and biochemical alterations at the levels of the vascular endothelium and smooth muscle cells. Blood in the subarachnoid space is believed to trigger these changes. In addition, cerebral perfusion may be concurrently impaired by hypovolemia and impaired cerebral autoregulatory function. The combined effects of these processes can lead to reduction in cerebral blood flow so severe as to cause ischemia leading to infarction. Diagnosis is made by some combination of clinical, cerebral angiographic, and transcranial doppler ultrasonographic factors. Nimodipine, a calcium channel antagonist, is so far the only available therapy with proven benefit for reducing the impact of DID. Aggressive therapy combining hemodynamic augmentation, transluminal balloon angioplasty, and intra-arterial infusion of vasodilator drugs is, to varying degrees, usually implemented. A panoply of drugs, with different mechanisms of action, has been studied in SAH related vasospasm. Currently, the most promising are magnesium sulfate, 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors, nitric oxide donors and endothelin-1 antagonists. This paper reviews established and emerging therapies for vasospasm.

Evidence-based cerebral vasospasm management

Cerebral vasospasm and delayed cerebral ischemia remain common complications of aneurysmal subarachnoid hemorrhage (SAH), and yet therapies for cerebral vasospasm are limited. Despite a large number of clinical trials, only calcium antagonists have strong evidence supporting their effectiveness. The purpose of this work was to perform a systematic review of the literature on the treatment of cerebral vasospasm. A literature search for randomized controlled trials of therapies used for prevention or treatment of cerebral vasospasm and/or delayed cerebral ischemia was conducted, and 41 articles meeting the review criteria were found. Study characteristics and primary results of these articles are reviewed. Key indicators of quality were poor when averaged across all studies, but have improved greatly over time. The only proven therapy for vasospasm is nimodipine. Tirilazad is not effective, and studies of hemodynamic maneuvers, magnesium, statin medications, endothelin antagonists, steroid drugs, anticoagulant/antiplatelet agents, and intrathecal fibrinolytic drugs have yielded inconclusive results. The following conclusions were made: nimodipine is indicated after SAH and tirilazad is not effective. More study of hemodynamic maneuvers, the effectiveness of other calcium channel antagonists such as nicardipine delivered by other routes (for example intrathecally), magnesium, statin drugs, endothelin antagonists, and intrathecal fibrinolytic therapy is warranted. There is less enthusiasm for the study of steroid drugs and anticoagulant/antiplatelet agents because they entail more risks and investigations so far have shown little evidence of efficacy. The study of rescue therapy such as balloon angioplasty and intraarterial vasodilating agents will be difficult. The quality of clinical trials should be improved.

Cerebral Vasospasm After Aneurysmal Subarachnoid Hemorrhage: An Overview of Pharmacologic Management

Cerebral vasospasm remains one of the leading causes of mortality in patients who experience a subarachnoid hemorrhage but survive the initial 24 hours. Vasospasm generally occurs 3-4 days after the initial subarachnoid hemorrhage and peaks at 5-7 days. The pathophysiology of vasospasm is poorly understood, which directly contributes to the inconsistency of management and creates a formidable challenge in clinical practice. Traditionally, hemodilution, hypervolemia, and induced hypertension (so-called triple H therapy); calcium channel blockers; and endovascular therapy have been used as either prophylactic therapy or treatment. However, management of vasospasm varies among physicians and institutions mainly because of a lack of large clinical trials and inconsistent results. Practice has been based primarily on case reports and the preference of each practitioner. Several experimental therapies have been explored; however, large, prospective, randomized controlled trials are needed to elucidate the role of these therapies.

Reduction of pulmonary edema after SAH with a pulmonary artery catheter-guided hemodynamic management protocol

INTRODUCTION

The frequency of pulmonary edema, which occurs with high frequency following subarachnoid hemorrhage (SAH), can be worsened by hypervolemic, hypertensive, hemodilution therapy for vasospasm. This study compares the complication rates for patients with SAH before and after institution of a pulmonary artery catheter-guided hemodynamic management protocol.

METHODS

Complication and outcome data were prospectively collected on 453 patients with spontaneous SAH. The patients were divided into groups treated from July 1998 through January 2000 (n = 174) and from February 2002 through June 2002 (n = 279). In group I, treatment consisted of hypervolemia (central venous pressures: >8 mmHg) and hypertension (mean arterial pressure: 110-130 mmHg). In group II, normovolemia was the goal, defined using a pulmonary artery catheter (wedge pressure: 10-14 mmHg). Cardiac output was enhanced (index: >4.5 L/minute/m2), and blood pressure elevations were moderated (mean pressure: >100 mmHg).

RESULTS

The average age, comorbidity, hemorrhage severity, and incidence of vasospasm were almost identical between the two groups. Statistically significant reductions were noted in patients in group II for two types of complications as well as for mortality. The rate of pulmonary edema (from 14 to 6%) and the rate of sepsis (from 14 to 6%) were both decreased (p <or= 0.03). Mortality decreased from 34 to 29% (p = 0.04). Other complications, such as myocardial infarction, were not affected.

CONCLUSIONS

These data show that a significant reduction in the frequency of pulmonary edema after SAH can be attained using a pulmonary artery catheter-guided hemodynamic management protocol.

Cerebral vasospasm in subarachnoid hemorrhage

The treatment of vasospasm after subarachnoid hemorrhage remains a formidable challenge. The prompt recognition of this complication is essential to prevent ischemic damage. Initial orders should include adequate fluid and sodium supplementation to avoid volume depletion. Prophylactic hypervolemia is not effective in reducing the incidence of vasospasm and may be deleterious. Oral nimodipine (60 mg every 4 hours for 21 days) should be started on admission because it protects against delayed ischemic damage. Increasing blood flow velocities on serial transcranial Doppler studies are reliable indicators of early development of vasospasm. When symptomatic vasospasm occurs, hemodynamic augmentation therapy should be instituted. Crystalloids and colloids may be used to promote hypervolemia. Colloids may provide additional benefit by producing hemodilution. However, the rheological benefits of hemodilution may be offset by reduced oxygen carrying capacity when hematocrit drops below 28%. Hypertension may be induced by administering inotropic drugs and, in certain cases, cardiac output optimization using dobutamine also is necessary. When aggressive medical therapy fails to reverse ischemic deficits, prompt endovascular intervention is indicated. Focal vasospasm of larger vessels may be effectively treated with angioplasty and the benefits of this procedure are durable. Diffuse vasospasm involving smaller arterial branches may be treated with intra-arterial infusion of vasodilators, such as papaverine, verapamil, or nicardipine. Unfortunately, these dilatory effects tend to be short-lasting. In refractory cases, hypothermia may be considered, although value of this strategy remains largely unexplored.

Circulatory volume expansion therapy for aneurysmal subarachnoid haemorrhage

BACKGROUND

Secondary ischaemia is a frequent complication after aneurysmal subarachnoid haemorrhage (SAH), and responsible for a substantial proportion of patients with poor outcome after SAH. The cause of secondary ischaemia is unknown, but hypovolaemia and fluid restriction are important risk factors. Therefore, volume expansion therapy (hypervolaemia) is frequently used in patients with SAH to prevent or treat secondary ischaemia.

OBJECTIVES

To determine the effectiveness of volume expansion therapy for improving outcome in patients with aneurysmal SAH.

SEARCH STRATEGY

We searched the Cochrane Stroke Group Trials Register (last searched September 2003). In addition we searched MEDLINE (1966 to January 2004) and EMBASE (1980 to January 2004) and contacted trialists to identify further published and unpublished studies.

SELECTION CRITERIA

All randomised controlled trials of volume expansion therapy in patients with aneurysmal SAH. We also sought controlled trials based on consecutive groups of patients quasi-randomly allocated to treatment or control group and included these in the analysis if the two groups were well comparable with regard to major prognostic factors.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted the data and assessed trial quality. Trialists were contacted to obtain missing information.

MAIN RESULTS

We identified three trials. One truly randomised trial and one quasi-randomised trial with comparable baseline characteristics for both groups were included in the analyses. Volume expansion therapy did not improve outcome (Relative Risk (RR) 1.0; 95% Confidence Interval (CI) 0.5 to 2.2), nor the occurrence of secondary ischaemia (RR 1.1; 95% CI 0.5 to 2.2). Hypervolaemia tended to increase the rate of complications (RR 1.8; 95% CI 0.9 to 3.7) In another quasi-randomised trial, outcome assessment was done only at the day of operation (7 to 10 days after SAH). In the period before operation, treatment resulted in a reduction of secondary ischaemia (RR 0.33; 95% CI 0.11 to 0.99) and case fatality (RR 0.20; 95% CI 0.07 to 1.2).

REVIEWERS' CONCLUSIONS

The effects of volume expansion therapy have been studied properly in only two trials of patients with aneurysmal SAH, with very small numbers. At present, there is no sound evidence for the use of volume expansion therapy in patients with aneurysmal SAH.

Therapeutic hypertension: principles and methods

The aspects of cardiovascular physiology important for the safe and effective implementation and titration of hypertensive therapy among neurosurgical patients with neurological or neurosurgical illness/injury are reviewed. Therapeutic hypertension may be an appropriate treatment for some neurological or neurosurgical conditions, e.g., vasospasm or support of cerebral perfusion pressure. Initiation and maintenance of hypertension should be done safely to avoid complications and/or undesired side effects. Accurate measurement of the arterial and central vascular pressures, the limitations of those methods, and alternative estimates of intravascular volume are reviewed. Hypertensive therapy is accomplished by modifying cardiac output and systemic vascular resistance, the principal physiological determinants of blood pressure. The goals of hypertensive therapy can be achieved by proper evaluation and manipulation of the four components of cardiac output, preload, afterload, heart rate and contractility. Measurement or calculation of estimates of these parameters is important in the selection of proper medications or supplemental fluid administration.

Albumin use in neurosurgical critical care

STUDY OBJECTIVE

To examine the use of albumin in patients receiving neurosurgical intensive care.

DESIGN

Survey and chart review of albumin use in neurosurgical intensive care units.

SETTING

University of Kentucky Chandler Medical Center and American Brain Injury Consortium (ABIC).

SUBJECTS

Thirty-eight patients who underwent neurosurgery at the University of Kentucky Chandler Medical Center; members of the ABIC.

INTERVENTIONS

Chart review with attention to administration of albumin; mailed survey to 200 ABIC members.

MEASUREMENTS AND MAIN RESULTS

Patients admitted to the neurosurgical intensive care unit at the University of Kentucky Chandler Medical Center over a 6-month interval were evaluated. Albumin, either 5% or 25%, was prescribed for approximately 25% of patients. The indications for use were vasospasm and maintenance of cerebral perfusion pressure. The response rate for the ABIC survey was 39%. Respondents stated that normal saline and albumin were both primary fluid choices for the treatment of vasospasm. Twenty-two percent reported a reduction in albumin prescribing following a formal warning statement issued by the Food and Drug Administration regarding the use of albumin in critically ill patients.

CONCLUSIONS

Chart review revealed the primary indications for albumin in the neurosurgical intensive care unit, and our survey data demonstrated the lack of consensus among neurosurgeons regarding their fluid of choice for neurosurgery indications. Prospective, randomized investigations comparing colloids to crystalloids in patients receiving neurosurgical intensive care are required to help define the role of albumin in neurosurgery patients.

Cerebral Vasospasm Following Subarachnoid Hemorrhage

Cerebral vasospasm and related ischemic stroke continue to be significant complicating factors in the course of many patients with subarachnoid hemorrhage from berry aneurysm rupture. The risk of this well-recognized but poorly understood complication can be estimated on the basis of patient medical history, neurologic examination, and head CT findings. Every patient with possible risk needs specialized neurologic intensive care unit care after aneurysm obliteration. Surgical and pharmacologic wash-out of subarachnoid blood around the basal arteries, proper management of intracranial pressure and fluid status, hyponatremia, hypomagnesemia, and fever, as well as use of calcium channel blockers, have been considered helpful in patient management prior to and with the symptomatic vasospasm development. Transcranial Doppler (TCD) ultrasound is important in detecting vasospasm before the patient suffers ischemic neurologic deficit or infarct. Elevated TCD velocities often initiate the use of triple-H (HHH: hypertension, hemodilution, and hypervolemia) therapy and subsequently guide it. Up to the end of the first 3 weeks after subarachnoid hemorrhage and aneurysm obliteration, development of any focal neurologic deficit or mental deterioration, unless convincingly proven otherwise, is assumed to be from cerebral vasospasm. When a hemodynamically significant vasospasm in the arterial segments of clinical concern is suggested, emergency cerebral angiography with balloon dilatation angioplasty or intra-arterial infusion of vasodilating agents may be helpful in relieving ischemic symptoms.