Treatment modalities for hypertensive patients with intracranial pathology: options and risks

Anesthesia care in the interventional neuroradiology suite: an update

PURPOSE OF REVIEW

The scope of procedures conducted by neurointerventionalists is expanding quickly, with lacking consensus over the best anesthesia modality. Although the procedures involve all age groups, the interventions may be complex and lengthy and may be provided in hospitals currently not yet familiar with the field. Here we review current literature addressing elective outpatient neurointerventional procedures and aim to provide an update on the management of intervention-specific crises, address special patient populations, and provide key learning points for everyday use in the neurointerventional radiology suite.

RECENT FINDINGS

Various studies have compared the use of different anesthesia modalities and preinterventional and postinterventional care. Monitored anesthesia care is generally recommended for elderly patients, whereas children are preferably treated with general anesthesia. Additional local anesthesia is beneficial for procedures, such as percutaneous kyphoplasty and vascular access.

SUMMARY

Combining different anesthetic modalities is a valuable approach in the neurointerventional radiology suite. More interventional and patient population-specific studies are needed to improve evidence-based perioperative management.

Management of Intracerebral Hemorrhage: Update and Future Therapies

PURPOSE OF REVIEW

Intracerebral hemorrhage (ICH) represents about 15% of all strokes in the USA, but almost 50% of fatal strokes. There are many causes of ICH, but the most common are hypertension and cerebral amyloid angiopathy. This review will discuss new advances in the treatment of intracerebral hemorrhage.

RECENT FINDINGS

The treatment of ICH focuses on management of edema, aggressive blood pressure reduction, and correction of coagulopathy. Early initiation of supportive medical therapies, including blood pressure management, in a neurological intensive care unit reduces mortality, but at present there is no definitive, curative therapy analogous to mechanical thrombectomy for ischemic stroke. Nonetheless, new medical and surgical approaches promise more successful management of ICH patients, especially new approaches to surgical management. In this review, we focus on the current standard of care of acute ICH and discuss emerging therapies that may alter the landscape of this devastating disease.

Management of Intracerebral Hemorrhage: JACC Focus Seminar

Intracerebral hemorrhage (ICH) accounts for a disproportionate amount of stroke-related morbidity and mortality. Although chronic hypertension and cerebral amyloid angiopathy are the underlying cerebral vasculopathies accounting for the majority of ICH, there are a broad range of potential causes, and effective management requires accurate identification and treatment of the underlying mechanism of hemorrhage. Magnetic resonance imaging and vascular imaging techniques play a critical role in identifying disease mechanisms. Modern treatment of ICH focuses on rapid stabilization, often requiring urgent treatment of mass effect, aggressive blood pressure reduction and correction of contributing coagulopathies to achieve hemostasis. We discuss management of patients with ICH who continue to require long-term anticoagulation, the interaction of ICH with neurodegenerative diseases, and our approach to prognostication after ICH. We close this review with a discussion of novel medical and surgical approaches to ICH treatment that are being tested in clinical trials.

Blood Pressure Management in Acute Stroke: Comparison of Current Guidelines with Prescribing Patterns

Objective:

Current recommendations for treating elevated blood pressure (BP) in the acute stroke are based largely on expert opinion and vary with regard to treatment thresholds and choice of antihypertensive agents. In this study we investigate the influence of these recommendations by comparing the management of hypertension in acute stroke at a tertiary care hospital with current guidelines.

Method:

Retrospective chart review of patients admitted with acute stroke at The Ottawa Hospital-General Campus over six consecutive months. The use of antihypertensive medications (type, dose, routes of administration, BP recordings) in the first seven days after admission was noted.

Results:

Transdermal nitroglycerin paste was the most commonly used antihypertensive agent. In contrast to the 15% reduction in BP over 24 hours recommended for lowering BP in hypertensive patients with ischemic stroke, nitroglycerin caused a >15% reduction of BPover the first 24 hours on 60% of the occasions used. Furthermore, despite concerns about sublingual nifedipine, this was the second most commonly prescribed agent. Surprisingly, the mean time to first BP measurement following initiation of antihypertensive therapy was 117 ± 43 minutes in ischemic stroke and 88 ± 89 minutes in hemorrhagic strokes.

Conclusions:

The current guidelines for management of acute poststroke hypertension appear to have little influence on prescribing patterns, leading to considerable variations in practice. Such variations, likely due to uncertainty caused by lack of evidence from randomised controlled trials, are intolerable as patients maybe submitted to nonstandardised, potentially harmful care such as inappropriate choice of antihypertensives and inadequate BP monitoring as observed in this study.

Quantitative magnetic resonance angiography as a potential predictor for cerebral hyperperfusion syndrome: a preliminary study

OBJECTIVE

Cerebral hyperperfusion syndrome (CHS) is a rare but devastating complication of carotid endarterectomy (CEA). This study sought to determine whether quantitative hemodynamic assessment using MR angiography can stratify CHS risk.

METHODS

In this prospective trial, patients with internal carotid artery (ICA) stenosis were randomly selected for pre- and postoperative quantitative phase-contrast MR angiography (QMRA). Assessment was standardized according to a protocol and included Doppler/duplex sonography, MRI, and/or CT angiography and QMRA of the intra- and extracranial supplying arteries of the brain. Clinical and radiological data were analyzed to identify CHS risk factors.

RESULTS

Twenty-five of 153 patients who underwent CEA for ICA stenosis were randomly selected for pre- and postoperative QMRA. QMRA data showed a 2.2-fold postoperative increase in blood flow in the operated ICA (p < 0.001) and a 1.3-fold increase in the ipsilateral middle cerebral artery (MCA) (p = 0.01). Four patients had clinically manifested CHS. The mean flow increases in the patients with CHS were significantly higher than in the patients without CHS, both in the ICA and MCA (p < 0.001). Female sex and a low preoperative diastolic blood pressure were the clearest clinical risk factors for CHS, whereas the flow differences and absolute postoperative flow values in the ipsilateral ICA and MCA were identified as potential radiological predictors for CHS.

CONCLUSIONS

Cerebral blood flow in the ipsilateral ICA and MCA as assessed by QMRA significantly increased after CEA. Higher mean flow differences in ICA and MCA were associated with the development of CHS. QMRA might have the potential to become a noninvasive, operator-independent screening tool for identifying patients at risk for CHS.

Neurologic complications of cardiac and vascular surgery

This chapter will provide an overview of the major neurologic complications of common cardiac and vascular surgeries, such as coronary artery bypass grafting and carotid endarterectomy. Neurologic complications after cardiac and vascular surgeries can cause significant morbidity and mortality, which can negate the beneficial effects of the intervention. Some of the complications to be discussed include ischemic and hemorrhagic stroke, seizures, delirium, cognitive dysfunction, cerebral hyperperfusion syndrome, cranial nerve injuries, and peripheral neuropathies. The severity of these complications can range from mild to lethal. The etiology of complications can include a variety of mechanisms, which can differ based on the type of cardiac or vascular surgery that is performed. Our knowledge about neuropathology, prevention, and management of surgical complications is growing and will be discussed in this chapter. It is imperative for clinicians to be familiar with these complications in order to narrow the differential diagnosis, start early management, anticipate the natural history, and improve outcomes.

Management of Brain Edema Complicating Stroke

Ischemic brain edema, the accumulation of fluid within the brain parenchyma following stroke, is a predictable consequence of both ischemic and hemorrhagic strokes. Its development is the result of injury to both brain parenchyma and the blood vessels supplying the parenchyma. Ischemic stroke produces both cytotoxic (intracellular) edema, which develops when cells are damaged, and vasogenic (extracellular) edema, which arises from injury to structures essential to blood-brain barrier integrity. An understanding of the distinction between cytotoxic and vasogenic edema is essential in preventing secondary brain injury, since the treatments for the two entities differ. The development of new brain imaging technologies has advanced our understanding of brain edema. Both computed tomography (CT) and magnetic resonance imaging (MRI) can detect edema. Specific MRI sequences such as diffusion-weighted imaging can distinguish cytotoxic and vasogenic subtypes, and thereby detect ischemic cell injury within minutes of the onset of symptoms.

Brain edema causes neurologic deterioration predominantly through its mass effect, which leads to distortion of the intracranial contents and impairment of both regional and global cerebral blood flow (CBF). Edema may also cause local tissue dysfunction. Management of the intracranial hypertension and tissue shifts caused by ischemic brain swelling is based on the fundamental relationship between pressure, flow, and resistance. Interventions are directed at preserving CBF and preventing secondary brain injury. Strategies include reducing intracranial blood volume with hypocapnia, reducing brain volume with osmotic agents, reducing cerebral metabolism with hypothermia and barbiturates, reducing resistance with rheologic agents, increasing blood pressure with vasoconstrictors, and expanding the cranial vault with decompressive surgery. All individual therapies must be used as part of a structured approach that involves frequent serial neurologic assessments, quantitative measures of pressure, flow, and resistance, and prespecified protocols for intervention.

Cardiovascular Manifestations of Acute Intracranial Lesions: Pathophysiology, Manifestations, and Treatment

The objective of this article was to review the effects of acute intracranial lesions on myocardial function. The authors reviewed scientific and clinical literature retrieved from a computerized MEDLINE search from January 1965 through January 2002. Pertinent literature was referenced, including clinical and laboratory investigations, to demonstrate the effects of acute intracranial lesions on the cardiovascular system. The literature was reviewed to summarize the mechanisms of cardiac damage and clinical manifestations and treatment of cardiovascular dysfunction caused by acute intracranial lesions. Myocardial damage and rhythm disturbances were shown to occur with acute intracranial neurological disease. The subgroup of patients used in this study formed a substantial pool of cardiac donors for cardiac transplantation. The pathophysiology of myocardial dysfunction and the optimal management continues to be a source of debate. In this article, the authors will review the anatomy, the available evidence of the pathophysiology, and the management of this complex group of patients. They will also discuss areas that need to be further investigated. Cardiovascular effects of acute intracranial lesions are common and contribute to increased morbidity and mortality.

Critical Care Management of Cerebral Edema in Brain Tumors

Cerebral edema associated with brain tumors is extremely common and can occur in both primary and metastatic tumors. The edema surrounding brain tumors results from leakage of plasma across the vessel wall into the parenchyma secondary to disruption of the blood-brain barrier. The clinical signs of brain tumor edema depend on the location of the tumor as well as the extent of the edema, which often exceeds the mass effect induced by the tumor itself. Uncontrolled cerebral edema may result in increased intracranial pressure and acute herniation syndromes that can result in permanent neurological dysfunction and potentially fatal herniation. Treatment strategies for elevated intracranial pressure consist of general measures, medical interventions, and surgery. Alhough the definitive treatment for the edema may ultimately be surgical resection of the tumor, the impact of the critical care management cannot be underestimated and thus patients must be vigilantly monitored in the intensive care unit. In this review, we discuss the pathology, pathophysiology, and clinical features of patients presenting with cerebral edema. Imaging findings and treatment modalities used in the intensive care unit are also discussed.

Cerebral autoregulation in the microvasculature measured with near-infrared spectroscopy

Cerebral autoregulation (CA) is the mechanism that allows the brain to maintain a stable blood flow despite changes in blood pressure. Dynamic CA can be quantified based on continuous measurements of systemic mean arterial pressure (MAP) and global cerebral blood flow. Here, we show that dynamic CA can be quantified also from local measurements that are sensitive to the microvasculature. We used near-infrared spectroscopy (NIRS) to measure temporal changes in oxy- and deoxy-hemoglobin concentrations in the prefrontal cortex of 11 human subjects. A novel hemodynamic model translates those changes into changes of cerebral blood volume and blood flow. The interplay between them is described by transfer function analysis, specifically by a high-pass filter whose cutoff frequency describes the autoregulation efficiency. We have used pneumatic thigh cuffs to induce MAP perturbation by a fast release during rest and during hyperventilation, which is known to enhance autoregulation. Based on our model, we found that the autoregulation cutoff frequency increased during hyperventilation in comparison to normal breathing in 10 out of 11 subjects, indicating a greater autoregulation efficiency. We have shown that autoregulation can reliably be measured noninvasively in the microvasculature, opening up the possibility of localized CA monitoring with NIRS.

Delayed cerebral hyperperfusion syndrome three weeks after carotid artery stenting presenting as status epilepticus

Cerebral hyperperfusion syndrome (CHS) is increasingly recognized as an uncommon, but serious, complication subsequent to carotid artery stenting (CAS) and carotid endarterectomy (CEA). The onset of CHS generally occurs within two weeks of CEA and CAS, and a delay in the onset of CHS of over one week after CAS is quite rare. We describe a patient who developed CHS three weeks after CAS with status epilepticus.

Anesthetic consideration for neurointerventional procedures

Interventional neuroradiology (INR) has been a rapidly expanding and advancing clinical area during the past few decades. As the complexity and diversity of INR procedures increases, the demand for anesthesia also increases. Anesthesia for interventional neuroradiology is a challenge for the anesthesiologist due to the unfamiliar working environment which the anesthesiologist must consider, as well as the unique neuro-interventional components. This review provides an overview of the anesthetic options and specific consideration of the anesthesia requirements for each procedure. We also introduce the anesthetic management for interventional neuroradiology performed in our medical institution.

Pre-Hospital Glyceryl Trinitrate: Potential for Use in Intracerebral Hemorrhage

BACKGROUND

Intracerebral hemorrhage is associated with poor clinical outcome and high mortality. Research and treatment modalities have focused on the expansion of the primary hematoma through blood pressure control and activation of coagulation factors. However, clinical trials have failed to show decreased rates of death or disability in intracerebral hemorrhage following hospital initiation of blood pressure control. However, as clinical deterioration often occurs immediately after onset, pre-hospital initiation of blood pressure control may be more ideal.

METHODS

Relevant terms in the National Library of Medicine PubMed database and selected research including basic science, translational reports, meta-analyses, and clinical studies were searched.

RESULTS

Trends indicating improved clinical outcome in intracerebral hemorrhage after hospital-initiated intensive systolic blood pressure control (goal<140 mmHg) have been demonstrated. Statistical significance may not have been obtained because of late treatment times of blood pressure control that approached median 4-6 hours after clinical onset. One trial utilizing glyceryl trinitrate in the pre-hospital setting has been shown to significantly decrease blood pressure within fifteen minutes and improve 90-day clinical outcome.

CONCLUSIONS

Glyceryl trinitrate represents an ideal pre-hospital blood pressure medication because it can be delivered via sublingual or transdermal routes, has a quick and graded onset of action, has neuroprotective effects, maintains cerebral perfusion, and has an established record of safety. As intracerebral hemorrhage requires prompt action to prevent clinical deterioration, more emphasis on pre-hospital therapies for blood pressure reduction will become essential in future therapies.

Fulminant Idiopathic Intracranial Hypertension With Malignant Systemic Hypertension-A Case Report

We describe a young woman who presented with malignant systemic hypertension and fulminant idiopathic intracranial hypertension. This is a rare combination, but both diagnoses should be considered in patients with optic disc swelling in whom cerebral imaging does not suggest an alternative cause. In this case, malignant hypertension was identified and treated before the idiopathic intracranial hypertension was recognised. Visual failure was evident at presentation and prior to blood pressure manipulation. It is likely that a combination of both conditions increased the vulnerability of the optic nerve head to ischaemic damage. It is also possible that reducing blood pressure in such patients, without treating coexisting raised intracranial pressure, may compound an already compromised ciliary arterial perfusion pressure. We therefore recommend careful blood pressure measurement in all patients presenting with idiopathic intracranial hypertension and advise that lumbar puncture is performed in patients with malignant hypertension with optic disc oedema, particularly in overweight young females.

Cerebral hyperperfusion syndrome after carotid intervention: a review

Cerebral hyperperfusion syndrome (CHS) after carotid surgery, although rare, is a well-described phenomenon. Although originally described after carotid endarterectomy, it has now also been described after carotid artery stenting. It is classically described as an acute neurologic deficit occurring several days after a carotid procedure, associated with severe hypertension and preceded by a severe headache. CHS represents a spectrum of clinical symptoms ranging from severe unilateral headache, to seizures and focal neurologic defects, to intracerebral hemorrhage in its most severe form. The exact mechanism leading to CHS is unknown; however, it seems to be related to increased regional cerebral blood flow secondary to loss of cerebrovascular autoregulation. Given the significant morbidity associated with CHS, researchers have been trying to identify which patients are most at risk. This is a difficult task given the rarity of the disease and the multiple confounding factors in the patient population who undergo carotid intervention. The goal was to determine those patients most at risk preoperatively, so that they may be more closely monitored postoperatively to prevent the development of CHS and its associated morbidity. The purpose of this review was to summarize the data currently available in the literature on CHS, with emphasis on pathophysiology, risk factor assessment, diagnostic modalities, and disease management, to provide insight for future research to better elucidate how to reduce the morbidity and mortality caused by CHS.

Blood Pressure Management in Acute Head Injury

Head injury remains a major cause of preventable death and serious morbidity in young adults. Based on the available evidence, it appears that a cerebral perfusion pressure of 50 to 70 mm Hg is generally adequate to ensure cerebral oxygen delivery and prevent ischemia. However, evidence suggests that perfusion requirements may not only vary across the injured brain but also differ depending on the time since injury. Such heterogeneity, both within and between subjects, suggests that individualized therapy may be an appropriate treatment strategy. Future studies should aim to assess which groups of patients, and what regional pathophysiological derangements, may benefit with improvements in functional outcome from therapeutic increases or decreases in cerebral perfusion pressure beyond these proposed limits. Such functional improvements may be of immense importance to patients and require formal neurocognitive assessments to discriminate improvements.

Perioperative hypertension management

Perioperative hypertension is commonly encountered in patients that undergo surgery. While attempts have been made to standardize the method to characterize the intraoperative hemodynamics, these methods still vary widely. In addition, there is a lack of consensus concerning treatment thresholds and appropriate therapeutic targets, making absolute recommendations about treatment difficult. Nevertheless, perioperative hypertension requires careful management. When treatment is necessary, therapy should be individualized for the patient. This paper reviews the pharmacologic agents and strategies commonly used in the management of perioperative hypertension.

Medical management of cerebral edema

✓Cerebral edema is frequently encountered in clinical practice in critically ill patients with acute brain injury from diverse origins and is a major cause of increased morbidity and death in this subset of patients. The consequences of cerebral edema can be lethal and include cerebral ischemia from compromised regional or global cerebral blood flow (CBF) and intracranial compartmental shifts due to intracranial pressure gradients that result in compression of vital brain structures. The overall goal of medical management of cerebral edema is to maintain regional and global CBF to meet the metabolic requirements of the brain and prevent secondary neuronal injury from cerebral ischemia. Medical management of cerebral edema involves using a systematic and algorithmic approach, from general measures (optimal head and neck positioning for facilitating intracranial venous outflow, avoidance of dehydration and systemic hypotension, and maintenance of normothermia) to specific therapeutic interventions (controlled hyperventilation, administration of corticosteroids and diuretics, osmotherapy, and pharmacological cerebral metabolic suppression). This article reviews and highlights the medical management of cerebral edema based on pathophysiological principles in acute brain injury.

Effects of benidipine, a long-lasting dihydropyridine-Ca2+ channel blocker, on cerebral blood flow autoregulation in spontaneously hypertensive rats

Chronic hypertension shifts cerebral blood flow (CBF) autoregulation towards higher blood pressure. We examined whether or not benidipine, a long-lasting dihydropyridine calcium channel blocker (CCB), improves the CBF autoregulation in spontaneously hypertensive rats (SHRs). CBF was analyzed by laser-Doppler flowmetry during stepwise hypotension by controlled bleeding. The lower limit of CBF autoregulation was calculated as the mean arterial blood pressure at which CBF decreased by 10% of the baseline. Mean arterial blood pressure and cerebral vascular resistance in SHRs were higher than those in normotensive Wistar rats. Oral administration of benidipine (3 mg/kg) for 8 d lowered the mean arterial blood pressure and cerebral vascular resistance, which were equivalent to the effects of amlodipine (3 mg/kg), another CCB, or candesartan (1 mg/kg), an Angiotensin II type-1 receptor blocker. The lower limit of CBF autoregulation in SHRs (142+/-4 mmHg) was significantly shifted to a higher-pressure level compared with Wistar rats (59+/-2 mmHg). The lower limit of CBF autoregulation was significantly lower in the benidipine-treated group (91+/-4 mmHg) than that in the control SHRs, and similar to that of the amlodipine group (97+/-6 mmHg). Benidipine reduced the lower limit of CBF autoregulation more effectively than candesartan (109+/-4 mmHg). In conclusion, benidipine shifted the limit of CBF autoregulation towards lower blood pressure in SHRs under hypotensive conditions by hemorrhage. These results suggest that benidipine may be useful for the treatment of hypertensive patients with the elderly or cerebrovascular disorders, in whom autoregulation of CBF is impaired.

Treatment of acute hypertension in patients with intracerebral hemorrhage using American Heart Association guidelines

OBJECTIVE

To determine the feasibility and safety of treatment of acute hypertension in patients with intracerebral hemorrhage within 24 hrs of symptom onset. Elevated blood pressure, observed in up to 56% of patients with intracerebral hemorrhage, may predispose to hematoma expansion; on the other hand, reduction of blood pressure may reduce hematoma expansion and subsequent death and disability.

DESIGN

Single-center prospective registry supplemented by retrospective chart review.

SETTINGS

University-affiliated medical center with dedicated stroke service.

PATIENTS

All patients admitted to the stroke service with spontaneous intracerebral hemorrhage and acute hypertension within 24 hrs of symptom onset.

INTERVENTION

Patients were treated with intravenous nicardipine within 24 hrs of symptom onset to reduce and maintain mean arterial pressure of <130 mm Hg. The mean arterial pressure goal was consistent with the American Heart Association guidelines.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the tolerability of the treatment as assessed by achieving and maintaining the mean arterial pressure goals for 24 hrs after initiation of intravenous nicardipine infusion. Other end points ascertained were: neurologic deterioration defined by a decline in Glasgow Coma Scale from pretreatment assessment by >or=2 points or increase in National Institutes of Health Stroke Scale score by >or=2 points and hemorrhage growth defined as an increase in the volume of intraparenchymal hemorrhage of >33% as measured by image analysis on the 24-hr computed tomographic scan compared with the baseline computed tomographic scan. Rates of favorable outcome and death were ascertained at 1 month. Of the total 46 patients admitted with intracerebral hemorrhage in our service, 29 patients were treated. Mean age of the treated patients was 58 +/- 13 yrs; ten were women. Initial National Institutes of Health Stroke Scale ranged from 1 to 38. The primary outcome of tolerability was achieved in 25 of the 29 patients (86%). Neurologic deterioration was observed in 4 of 29 patients. Hematoma enlargement was observed in five patients. Favorable outcome (defined as modified Rankin scale of <or=2) and death at 1-month was observed in 11 (38%) and 9 (31%) of the 29 patients, respectively.

CONCLUSIONS

We observed a high rate of tolerability among patients with intracerebral hemorrhage who were treated with intravenous nicardipine using mean arterial pressure goals defined by American Heart Association guidelines within 24 hrs of symptom onset.

Cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome (CHS) after carotid endarterectomy is characterised by ipsilateral headache, hypertension, seizures, and focal neurological deficits. If not treated properly it can result in severe brain oedema, intracerebral or subarachnoid haemorrhage, and death. Knowledge of CHS among physicians is limited. Most studies report incidences of CHS of 0-3% after carotid endarterectomy. CHS is most common in patients with increases of more than 100% in perfusion compared with baseline after carotid endarterectomy and is rare in patients with increases in perfusion less than 100% compared with baseline. The most important risk factors in CHS are diminished cerebrovascular reserve, postoperative hypertension, and hyperperfusion lasting more than several hours after carotid endarterectomy. Impaired autoregulation as a result of endothelial dysfunction mediated by generation of free oxygen radicals is implicated in the pathogenesis of CHS. Treatment strategies are directed towards regulation of blood pressure and limitation of rises in cerebral perfusion. Complete recovery happens in mild cases, but disability and death can occur in more severe cases. More information about CHS and early institution of adequate treatment are of paramount importance in order to prevent these potentially severe complications.

A prospective multicenter study to evaluate the feasibility and safety of aggressive antihypertensive treatment in patients with acute intracerebral hemorrhage

The authors performed a multicenter prospective observational study to evaluate the feasibility and safety of intravenous antihypertensive protocol for acute hypertension in patients with intracerebral hemorrhage (ICH). Twenty-seven patients with ICH and acute hypertension (mean age 61.37 +/- 14.27; 10 were men) were treated to maintain the systolic blood pressure (BP) below 160 mm Hg and diastolic BP below 90 mm Hg within 24 hours of symptom onset. Neurological deterioration (defined as a decrease in initial Glasgow Coma Scale score > or = 2) was observed in 2 (7.4%) of 27 patients during treatment. Among patients who underwent follow-up computed tomography, hematoma expansion (more than 33% increase in hematoma size at 24 hours) was observed in 2 (9.1%) of 22 patients. Patients treated within 6 hours of symptom onset were more likely to be functionally independent (modified Rankin scale < or = 2) at 1 month compared with patients who were treated between 6 and 24 hours (8 of 18 versus 0 of 9,P = .03). Aggressive pharmacological treatment of acute hypertension in patients with ICH can be initiated early with a low rate of neurological deterioration and hematoma expansion.

Modifications hémodynamiques cérébrales et systémiques au moment du réveil en neurochirurgie

Major complications after intracranial surgery occur in 13-27% of patients. Among multiple causes, haemodynamic and metabolic changes of anaesthesia recovery may be responsible for intracranial complications. Recovery from neurosurgical anaesthesia is followed by an increase in body oxygen consumption and catecholamines concentrations. However, in normothermic patients, theses changes are usually mild and not prevented by a 2-h recovery delay. Systemic hypertension is common after neurosurgery and a link between perioperative hypertension and intracranial haemorrhage has been established. The cerebral consequences of recovery associate cerebral hyperaemia and increased ICP in patients with a tight brain at the end of surgery. Cerebral hyperaemia may promote or exacerbate cerebral haemorrhage or oedema. This has been demonstrated in patients operated for subdural haematoma removal or undergoing carotid surgery. Prevention of hypothermia and pain are key factors to prevent metabolic changes. Beta-blockers seem to be suitable agents to obtain haemodynamic control in neurosurgical patients.

Prehemorrhage risk factors for fatal intracranial aneurysm rupture

BACKGROUND AND PURPOSE

The goal of this study was to investigate predictive preictal risk factors for fatal subarachnoid hemorrhage (SAH) in a patient population with verified intracranial aneurysms without surgical selection of patients and with complete follow-up.

METHODS

A total of 142 patients with 181 unruptured aneurysms diagnosed between 1956 and 1978 were followed up for a total of 2577 person-years until death, SAH, or the years 1997 to 2000. The predictive value of several factors known before SAH was tested for case fatality.

RESULTS

During follow-up, 34 first episodes of hemorrhage from a previously verified unruptured aneurysm occurred. Of these bleeding episodes, 17 were fatal. Patients who died after the bleeding had higher blood pressure values (mean+/-SD, 148+/-11/92+/-8 mm Hg; mean pressure, 111+/-9 mm Hg) before hemorrhage than did those with nonfatal bleeding (mean+/-SD, 135+/-15/83+/-11 mm Hg; mean, 101+/-12 mm Hg) (P<0.05). Patients with fatal SAH were also older (54+/-7 versus 47+/-13 years, P=0.068) and had aneurysms larger in diameter (13+/-8 versus 10+/-5 mm) than those who survived. They had a higher prevalence of definite hypertension (56% versus 12%, P<0.05), more frequently used antihypertensive medication (29% versus 6%) by the end of follow-up, and tended to have higher blood pressure at the beginning of follow-up (140+/-21/85+/-11 versus 134+/-17/80+/-9 mm Hg). After adjustment for age, aneurysm size, and sex, the only indisputable significant independent risk factor for fatal SAH compared with nonfatal SAH was systolic blood pressure before aneurysm rupture (odds ratio, 1.11 per 1 mm Hg; 95% CI, 1.01 to 1.23; P=0.032). The adjusted odds ratio of definite hypertension for fatal SAH was 12.67 (95% CI, 1.53 to 104.70; P=0.018).

CONCLUSIONS

Increased systolic blood pressure values and long-term hypertension before aneurysm rupture seem to predict fatal SAH independently of aneurysm size or patient age or sex at the time of rupture.

Severely increased blood pressure in the emergency department

Patients with severely increased blood pressure often present to the emergency department. Emergency physicians evaluate and treat hypertension in various contexts, ranging from the compliant patient with well-controlled blood pressure to the asymptomatic patient with increased blood pressure to the critically ill patient with increased blood pressure and acute target-organ deterioration. Despite extensive study and national guidelines for the assessment and treatment of chronically increased blood pressure, there is no clear consensus on the acute management of patients with severely increased blood pressure. In this article, we examine the broad spectrum of disease, from the asymptomatic to critically ill patient, and the dilemma it creates for the emergency physician in deciding how and when in the process to intervene.

Ischaemic brain oedema

Ischaemic brain oedema appears to involve two distinct processes, the relative contribution and time course of which depend on the duration and severity of ischaemia, and the presence of reperfusion. The first process involves an increase in tissue Na+ and water content accompanying increased pinocytosis and Na+, K+ ATPase activity across the endothelium. This is apparent during the early phase of infarction and before any structural damage is evident. This phenomenon is augmented by reperfusion. A second process results from a more indiscriminate and delayed BBB breakdown that is associated with infarction of both the parenchyma and the vasculature itself. Although, tissue Na+ level still seems to be the major osmotic force for oedema formation at this second stage, the extravasation of serum proteases is an additional potentially deleterious factor. The relative importance of protease action is not yet clear, however, degradation of the extracellular matrix conceivably leads to further BBB disruption and softening of the tissue, setting the stage for the most pronounced forms of brain swelling. A number of factors mediate or modulate ischaemic oedema formation, however, most current information comes from experimental models, and clinical data on this microcosmic level is lacking. Clinically significant brain oedema develops in a delayed fashion after large hemispheric strokes and is a cause of substantial mortality. Neurological signs appear to be at least as good as direct ICP measurement and neuroimaging in detecting and gauging the secondary damage produced by stroke oedema. The neuroimaging characteristics of the stroke, specifically the early involvement of greater than half of the MCA territory, are, however, highly predictive of the development of severe oedema over the subsequent hours and days. None of the available medical therapies provide substantial relief from the oedema and raised ICP, or at best, they are temporizing in most cases. Hemicraniectomy appears most promising as a method of avoiding death from brain compression, but the optimum timing and manner of patient selection are currently being investigated. All approaches to massive ischaemic brain swelling are clouded by the potential for survival with poor functional outcome. It is possible to manage blood pressure, serum osmolarity by way of selective fluid administration, and a number of other systemic factors that exaggerate brain oedema. Broad guidelines for treatment of stroke oedema can therefore be given at this time.

Decrease in jugular venous oxygen saturation during normothermic cardiopulmonary bypass predicts short-term postoperative neurologic dysfunction in elderly patients

OBJECTIVES

We sought to examine whether the decrease in jugular venous oxygen saturation (SjvO(2)) during cardiopulmonary bypass (CPB) can be used to predict short-term and long-term postoperative cognitive disorders in elderly patients.

BACKGROUND

It has been reported that elderly patients might be more susceptible to hypoperfusion during CPB.

METHODS

One hundred eighty-five patients scheduled for elective coronary artery bypass graft surgery were studied. Group 1 (n = 56) was young (<50 years old), group 2 (n = 67) was middle-aged (50 to 69 years old) and group 3 (n = 62) was elderly (>70 years old). After induction of anesthesia, a fiberoptic oximetry oxygen saturation catheter was inserted into the right jugular bulb to monitor SjvO(2) continuously. Hemodynamic variables and arterial and jugular venous blood gases were measured at seven time points.

RESULTS

The cerebral desaturation time (duration when SjvO(2) was <50%) and the ratio of the cerebral desaturation time to the total CPB time in group 3 were significantly different from those in groups 1 and 2 (group 1: 20 +/- 6 min and 16 +/- 5%; group 2: 19 +/- 7 min and 14 +/- 6%; group 3: 34 +/- 9 min and 24 +/- 7%, respectively; p < 0.05). Also, age (odds ratio [OR] 1.3, 95% confidence interval [CI] 1.0 to 1.8, p = 0.02) and desaturation time (OR 1.3, 95% CI 1.0 to 1.4, p = 0.03) were perioperative factors in relation to short-term cognitive impairment. However, age and desaturation time were not perioperative factors in relation to long-term cognitive impairment.

CONCLUSIONS

Reduced SjvO(2) was associated with short-term cognitive dysfunction in elderly patients.

Intracranial pressure and surgical decompression for traumatic brain injury: biological rationale and protocol for a randomized clinical trial

Commonly, severe traumatic brain injury (TBI) patients undergo amputation of contused brain; the rationale being that edema in presumed unsalvageable cerebrum increases intracranial pressure (ICP). Neuro-critical care expends great effort to control ICP and prevent secondary injury. Non-randomized investigations have employed hemicraniectomy with duraplasty after developing refractory ICP. We undertook a randomized pilot of hemicraniectomy with duraplasty as the initial surgery for severe TBI patients. Goals included reduced ICP therapeutic intensity and return to the operating room, and improved neurological outcome. Upon hospital presentation, the study was to randomize 92 patients with midline shift greater than the size of a surgically removable hematoma. One group was to receive standardized hemicraniectomy and duraplasty; the other would undergo 'traditional' craniotomy (with brain amputation at the neurosurgeon's discretion). A standardized medical protocol followed. The six-month Glasgow Outcome Scale was the primary outcome, with secondary measures including quality of life one year after TBI, duration and frequency of elevated ICP, intensive care unit (ICU) therapeutic intensity, operating room return, and ICU and hospital lengths-of-stay. This article presents the biological rationale and the evidence-based standardized protocols of the study and its outcome measures. The study has stopped and a phase III outcome trial is being organized.

Acute care management of severe traumatic brain injuries

Preservation or restoration of optimal neurologic function following traumatic brain injury (TBI) requires timely and aggressive therapeutic interventions. Effective diagnostic tools, together with an armamentarium of treatment modalities, have augmented the treatment strategies utilized today. In addition, the Guidelinesfor the Management of Severe Head Injury have established a standardized approach for the TBI patient. This article will provide current information regarding the resuscitation priorities, appropriate interventions, and pharmacological agents used in the treatment required by the complex nature of TBI. Also, a review of the occurrences associated with TBI will be discussed.

Intensive care unit management of the stroke patient

Although the majority of patients with acute stroke do not require intensive care, it is important to recognize when admission to an intensive care unit (ICU) is warranted. Patients undergoing thrombolytic therapy, those with brainstem infarcts referable to the basilar artery, those with large space occupying hemispheric infarcts, and those with fluctuating neurological examinations should be admitted to the ICU for monitoring and treatment.

Long-term outcome after medical reversal of transtentorial herniation in patients with supratentorial mass lesions

OBJECTIVE

To determine the short- and long-term outcomes after successful reversal of transtentorial herniation by medical treatment. Although it has been recognized that aggressive medical management can reverse transtentorial herniation, it is believed that overall outcome in such patients is poor.

DESIGN

Prospective cohort study.

SETTING

Neurocritical care unit of a university hospital.

PATIENTS

A total of 28 consecutive patients who underwent an episode of transtentorial herniation (defined as decrease in level of consciousness accompanied by pupillary dilation) secondary to a supratentorial mass lesion followed by successful reversal.

INTERVENTION

Herniation was reversed by using a combination of hyperventilation, mannitol and hypertonic saline.

MEASUREMENTS AND MAIN RESULTS

The following outcomes were analyzed: risk of second herniation, radiologic evidence of structural damage or vascular compromise related to herniation on post-herniation computed tomographic scan, in-hospital mortality, and long-term functional outcome using Rankin score and Barthel index. A total of 32 episodes of transtentorial herniations were reversed in 28 patients during a 14-month period. The most common precipitating cause were edema (n = 23) or new/expanding intracerebral hematoma (n = 5). After first reversal of transtentorial herniation in 28 patients, a second herniation episode was observed in 16 patients after a mean interval of 88.2 hrs (range, 23-432 hrs); four were successfully reversed. On follow-up computed tomographic scan, hypodense lesion in midbrain (n = 6), temporal lobe contusion (n = 2), posterior cerebral artery (n = 3), and middle cerebral artery (n = 1) infarction were visualized in a minority of patients. The in-hospital mortality was 60% (n = 15) with brain death being the cause of death in 13 patients; care was withdrawn in eight patients. Second episode of herniation (p = .002) and midbrain involvement during herniation (p = .02) were associated with in-hospital mortality. During a mean follow-up period of 11.4+/-4.2 months, two patients died of cerebral neoplasm and human immunodeficiency virus-related sepsis, respectively. Of the 11 survivors, 7 were functionally independent (Rankin score <3 and Barthel index >60).

CONCLUSIONS

Although mortality after transtentorial herniation is high, we found a prominent potential for meaningful recovery with aggressive medical reversal of transtentorial herniation. Our study implies that timely medical intervention for reversing transtentorial herniation can result in preservation of neurologic function.

Treatment of hypertension in the perioperative patient

OBJECTIVE

To review studies and drug therapy relating to the treatment of hypertension in perioperative patients.

DATA SOURCES

Articles were selected from a MEDLINE search (1966-August 1998), and several textbooks on hypertension and surgery were reviewed. In addition, bibliographies of all articles and textbook chapters were studied for articles not found in the computerized searches.

STUDY SELECTION

Clinical studies involving hypertension in the perioperative setting were included. The initial search was limited to studies conducted in humans and published in English.

DATA EXTRACTION

Information regarding drug therapy was reviewed and guidelines were constructed for managing surgical patients with acute blood pressure elevations.

DATA SYNTHESIS

Although nitroprusside and nitroglycerin, with their short onset of action and duration of effect, are indicated for hypertensive emergencies, a variety of agents are available for hypertensive urgencies. An algorithm that can be used as a template for the development of intrainstitutional guidelines is provided.

CONCLUSIONS

Due to the scarcity of comparative trials, decisions involving agents for the treatment of perioperative hypertension must often be made based on combined efficacy, toxicity, cost, and convenience considerations.

The neglected prehospital phase of head injury: apnea and catecholamine surge

The prehospital phase of head injury, also called the critical phase, consists of trauma-induced apnea and stress catecholamine release. This immediate period after head injury remains poorly summarized in the literature and essentially ignored with respect to treatment. A MEDLINE search of the literature on apneustic response and catecholamine surge after head injury and a review of literature from my acquired references revealed 116 references (from more than 600) that were pertinent. Apnea induced by head injury produces hypoxia, hypercarbia, and subsequent cardiac failure and hypotension, which, along with substantially elevated catecholamine values, promote secondary mechanisms of organ injury. Treatment for this immediate period after head injury requires a rapid response to the scene of trauma and development of treatment options that can be instituted at the scene of injury.

Cerebral oxygenation during prostaglandin E1 induced hypotension

PURPOSE

To evaluate the cerebral oxygenation effects of hypotension induced by prostaglandin E1 (PGE1) during fentanyl-oxygen anaesthesia.

METHODS

Ten patients who underwent elective cardiac surgery received infusion of PGE1. After measuring the baseline arterial, mixed venous and internal jugular vein blood gases, systemic haemodynamics, and regional cerebral oxygen saturation (rSO2) estimated by INVOS 3100R, PGE1 was continuously infused at 0.25-0.65 microgram.kg-1.min-1 (mean dosage: 410 +/- 41.4 mg.kg-1.min-1) intravenously. Ten, 20 and 30 minutes after the start of drug infusions, blood gases described above were obtained simultaneously with the measurement of systemic haemodynamics and rSO2. Thirty minutes from the start of drug infusions, administration of PGE1 was stopped. The same parameters were measured again 10, 30 minutes after the stop of drug infusion.

RESULTS

PGE1 decreased mean arterial pressure (MAP) to approximately 70% of the baseline value (P < 0.05). PGE1 increased mixed venous saturation, but in contrast did not affect internal jugular pressure, internal jugular oxygen saturation and rSO2.

CONCLUSIONS

These results suggest that PGE1 is a suitable drug for induced hypotension because flow/metabolism coupling of brain and regional cerebral oxygenation were well maintained during hypotension.

Assessment of cerebral pressure autoregulation in humans--a review of measurement methods

Assessment of cerebral autoregulation is an important adjunct to measurement of cerebral blood flow for diagnosis, monitoring or prognosis of cerebrovascular disease. The most common approach tests the effects of changes in mean arterial blood pressure on cerebral blood flow, known as pressure autoregulation. A 'gold standard' for this purpose is not available and the literature shows considerable disparity of methods and criteria. This is understandable because cerebral autoregulation is more a concept rather than a physically measurable entity. Static methods utilize steady-state values to test for changes in cerebral blood flow (or velocity) when mean arterial pressure is changed significantly. This is usually achieved with the use of drugs, shifts in blood volume or by observing spontaneous changes. The long time interval between measurements is a particular concern in many of the studies reviewed. Parallel changes in other critical variables, such as pCO2, haematocrit, brain activation and sympathetic tone, are rarely controlled for. Proposed indices of static autoregulation are based on changes in cerebrovascular resistance, on parameters of the linear regression of flow/velocity versus pressure changes, or only on the absolute changes in flow. The limitations of studies which assess patient groups rather than individual cases are highlighted. Newer methods of dynamic assessment are based on transient changes in cerebral blood flow (or velocity) induced by the deflation of thigh cuffs, Valsalva manoeuvres, tilting and induced or spontaneous oscillations in mean arterial blood pressure. Dynamic testing overcomes several limitations of static methods but it is not clear whether the two approaches are interchangeable. Classification of autoregulation performance using dynamic methods has been based on mathematical modelling, coherent averaging, transfer function analysis, crosscorrelation function or impulse response analysis. More research on reproducibility and inter-method comparisons is urgently needed, particularly involving the assessment of pressure autoregulation in individuals rather than patient groups.

Parenteral hydralazine revisited

Historical aspects of the development and application of the vasodilator hydralazine are reviewed. The pharmacology, pharmacokinetics, metabolism, and mechanism of action are discussed, with emphasis on the parenteral use of this drug. It is reiterated that parenteral hydralazine is the preferred drug for the treatment of severe preeclampsia, but its usefulness in other forms of accelerated hypertension is also addressed. Through comparisons with other established antihypertensive agents, the efficacy and pharmacoeconomic potential of hydralazine are stressed.

Hypertension in the elderly: don't treat too quickly!

In the asymptomatic patient without target organ damage who is seen with severely elevated BP, pseudohypertension is more often than not the cause. Rapid lowering of arterial pressure is unnecessary and even contraindicated. Nurses play an important role in the evaluation and the treatment of elderly patients with hypertension. Both research-based practice and thorough evaluation and monitoring are requisite for safe and effective treatment. Given the seriousness of the adverse effects and the lack of outcome data, the use of sublingual nifedipine capsules in hypertensive emergencies and pseudohypertension should be abandoned.

The differential effects of prostaglandin E1 and nitroglycerin on regional cerebral oxygenation in anesthetized patients

We evaluated the effects of prostaglandin E1 (PGE1) and nitroglycerin (NTG) on regional tissue oxygenation and use in the brain using near infrared spectroscopy (NIRS). Twenty-four patients who underwent elective cardiac surgery were randomly divided into two groups. The study was performed after the induction of anesthesia and before the start of the surgical procedure. After measuring arterial and jugular venous blood gases, cardiovascular hemodynamics, and relative cerebral oxyhemoglobin (HbO2), deoxyhemoglobin, and cytochrome aa3 at the baseline, PGE1 (n = 12) or NTG (n = 12) was infused intravenously at a rate of 0.3 g/kg or 5 g/kg, respectively. Thirty minutes after the start of drug infusion, administration of the drugs was stopped. Both PGE1 and NTG reduced mean arterial pressure to approximately 70% of the baseline value 10, 20, and 30 min after start of drug infusion (P < 0.05). Internal jugular venous pressure increased significantly during NTG but not during PGE1 infusion (P < 0.05). PGE1 increased HbO2 concentration, which was sustained for 30 min after discontinuing the drug. NTG increased HbO2 concentration, but this gradually returned to the baseline level after discontinuation of the drug. Baseline value of jugular oxygen saturation was 64.5% +/- 2.1%, and there was no significant changes during the infusion of PGE1 or NTG. These results demonstrate that both NTG and PGE1 increased cerebral oxygen saturation as measured by NIRS. This may be explained by local cerebral hyperemia without major alteration in flow/metabolism coupling of brain. The onset of this increase was slower and the duration of this effect after discontinuation of the drug was more prolonged with PGE1. These phenomena occurred despite the relatively similar time course of the effect of these two drugs on systemic hemodynamic values.

IMPLICATIONS

The cerebrovascular effects of vasodilators used for induced hypotension are not fully understood. In this study, we used near infrared spectrometry and jugular oxygen saturation measurement to assess the effects of prostaglandin E1 and nitroglycerin on cerebral perfusion. We found that nitroglycerin and prostaglandin E1 increase cerebral oxygen saturation as measured by near infrared spectrometry, but with different time courses. This information will hopefully help anesthesiologists to better maintain adequate regional cerebral oxygenation.