NEUROCRITICAL INTENSIVE CARE UNITS IMPROVE OUTCOMES IN PATIENTS WITH INTRACEREBRAL HEMORRHAGE

Vast increases in medical knowledge have led far beyond provider specialization into the development of specialized teams and specialized hospital units. The argument for evidence-based care delivered by experts in a specific disease process or condition is rather compelling.¹ This is often extended into dedicated units, in which teams with specific expertise provide care. As in other areas of medicine that use this approach, the creation of dedicated neurocritical intensive care units (NICUs) has led to a critical evaluation of the current evidence behind calls for their creation.

Several papers support the stance that specialized critical care units improve outcomes in patients with acute brain injury. Ischemic stroke and nontraumatic intracerebral hemorrhage (ICH) are often lumped together in studies on critical care management, though, obviously, different pathophysiologic processes are involved. If improved outcomes are the issue, a critical examination of the outcome measures used in each study is important in analyzing the reports. Lengths of stay and hospitalization costs are easy metrics to follow; lessened clinical disability is more difficult to assess. While clinical outcome measures exist and are widely adopted, no single outcome measure can describe or predict all dimensions of recovery and disability after acute stroke.² In addition, in a disease process like ICH, in which morbidity and mortality are extremely high, the issues of futility and withdrawal of care confound interpretation of the studies. If care is withdrawn from a patient with brain injury who is thought to be without hope of good recovery, then the poor outcome (as defined by mortality) becomes self-fulfilling.^3,4,5 However, if the outcomes reported are improved length of stay measures and decreased costs, early withdrawal of care could, conceivably, positively impact these measures.

In a large retrospective study from a database of multiple institutions, Diringer found that, for patients with nontraumatic ICH, admission to a NICU was associated with a lower mortality rate than admission to a general intensive care unit (ICU).⁶ Another retrospective review of patients with ICH who required critical care compared outcomes of patients admitted to a new neurosciences ICU to the outcomes of historical controls, who were treated in medical or surgical ICUs at the same institution. Mirski found that mortality measures improved with the introduction of the specialty ICU, as did length of stay measures and total costs of care.⁷

In another single-institution study, Varelas found that the appointment of a neurointensivist to a small ICU was associated with positive outcomes. A neurointensivist-led team, along with the transition of the ICU from an open unit model to a semi-closed model, was associated with fewer complications and improved outcomes, including lower ICU mortality, shortened length of stay, and improved discharge destinations.⁸ Finally, reorganization of resources to provide a neurocritical care team led by a neurointensivist was reported to reduce in-hospital mortality, NICU length of stay, and overall hospital length of stay.⁹

For stroke, the most aggressive push to promote guidelines and evidence-based care has come from the Brain Attack Coalition (BAC). Recommendations by the BAC state that a neurosciences ICU is desirable in medical centers for designation as a comprehensive stroke center, but they stop short of mandating a dedicated neuroscience ICU.¹⁰ This recommendation has been challenged by neurocritical care physicians who feel that a dedicated neuroscience ICU should be mandatory.¹¹

are specific treatments important for improved outcomes?

A more thought-provoking question related to this topic is: Why are outcomes improved? Specific treatments generally used in NICUs for the management of ICH include intracranial pressure (ICP) measurement and management of ICP with osmotic agents, ventriculostomy, ventilator management, and other therapies. Treatment of hypertension is often initiated, though clear evidence-based guidelines for such treatment in this clinical situation do not exist. Preservation of cerebral perfusion pressure by volume expansion and use of pressors to avoid hypotension in patients with brain injuries is a more recent area of focus. Large, rigorous, prospective, randomized studies are currently lacking for all of these therapies. If specific treatments are of unknown benefit, it is difficult to imagine that protocol-driven care using those specific treatments is the cause of the benefit observed in patients treated in NICUs.

Diringer stated that data were not sufficient in his 2001 study to determine the factors that might account for the improved mortality differences.⁶ He thought that different approaches to management of hypertension, withdrawal of care, correction of coagulopathy, resident supervision, caregiver training and experience, and nurse-to-patient ratio might all be factors.⁶ Diringer later speculated, in editorial comments, not only that bedside decisions in individual patients would lead to improvements but also that the enhanced education and leadership that influences how a specialized unit functions might be responsible for the improved outcomes.¹² In another editorial, Gore advances the idea that a dedicated team likely makes the greatest impact by standardizing diagnosis and management of common clinical problems.¹³

return to the basics

An axiom of resuscitation is to stabilize airway, breathing, and circulation (ie, the ABCs) before continuing to more advanced interventions. With regard to neurointensive care in ICH, the ideal goals for the basic ABCs are still unknown. Methods of airway control and the selection of patients with ICH in whom airway control should be initiated remain undefined. After years of hyperventilating patients with brain injuries with the goal of reducing ICP, hyperventilation is now avoided except in a most modest form. Many different recommendations for blood pressure management exist, but none are evidence-based and driven by outcomes. Hyperglycemia likely is best avoided, but the goals of glycemic management in patients with ICH remain unclear. Hyperthermia is also thought to be best avoided, but the means of intervention and the temperature at which interventions should be initiated are not well studied. Whether hypothermia improves outcomes specifically in patients with ICH is far from completely studied.

future opportunities

Future studies should identify interventions that improve outcomes, including the most basic of interventions. Identification of outcomes from these types of interventions will likely require large-scale randomized clinical trials. The studies should be targeted to maximize the potential for success by initiating proposed therapies as early in the course of treatment as possible. Some such studies will likely be started in the emergency department or prehospital environment with coordinated transition to the NICU. Other studies may be started within the NICU, and all studies will require carefully standardized care in order to determine the actual effect of the intervention being studied. As with all clinical research, the coordination of care that allows such studies to be done properly may itself have an impact on patient outcomes.

Despite the lack of evidence from randomized clinical trials, coordinated care performed by experts in a discipline can improve outcome in patients with ICH. Some comfort can be taken in the fact that nonrandomized studies do support this effect of dedicated NICUs. While looking forward to the results of controlled trials that examine individual interventions, recognize that the creation of the environment in which such trials can be done may well affect outcome.

REFERENCES

1. Ellrodt G, Cook DJ, Lee J, et al. Evidence-based disease management. JAMA. 1997;278(20):1687-92.
2. Kasner SE. Clinical interpretation and use of stroke scales. Lancet Neurol. 2006;5(7):603-12.
3. Becker KJ, Baxter AB, Cohen WA, et al. Withdrawal of support in intracerebral hemorrhage may lead to self-fulfilling prophecies. Neurology. 2001;27:766-72.
4. Mirsen TR. Futility in stroke care-still a concept in progress. Crit Care Med. 2004;32:2365-6.
5. Hemphill JC 3rd, Newman J, Zhao S, Johnston SC. Hospital usage of early do-not-resuscitate orders and outcome after intracerebral hemorrhage. Stroke. 2004;35(5):1130-4.
6. Diringer MN, Edwards DF. Admission to a neurologic/neurosurgical intensive care unit is associated with reduced mortality rate after intracerebral hemorrhage. Crit Care Med. 2001;29:635-40.
7. Mirski MA, Chang CW, Cowan R. Impact of a neuroscience intensive care unit on neurosurgical patient outcomes and cost of care: evidence-based support for an intensivist-directed specialty ICU model of care. J Neurosurg Anesthesiol. 2001;13:83-92.
8. Varelas PN, Conti MM, Spanaki MV, et al. The impact of neurointensivist-led team on a semiclosed neurosciences intensive care unit. Crit Care Med. 2004;32:2191-8.
9. Suarez JI, Zaidat OO, Suri MF, et al. Length of stay and mortality in neurocritically ill patients: impact of a specialized neurocritical care team. Crit Care Med. 2004;32:2311-7.
10. Alberts MJ, Latchaw RE, Selman WR, et al. Recommendations for comprehensive stroke centers: a consensus statement from the Brain Attack Coalitions. Stroke. 2005;36:1597-618.
11. Hemphill JC, Bleck T, Carhuapoma JR, et al. Is neurointensive care really optimal for comprehensive stroke care? Stroke. 2005;36:2344-5.
12. Diringer MN. Bringing order to chaos. Crit Care Med. 2004;32:2346.
13. Gore DC, Prough DS. Impact of intensivists on outcome of critically ill neurologic and neurosurgical patients. Crit Care Med. 2004;32:2363-4.