NCI200147_Layout 1 09/07/11 6:20 PM Page 177 AACN Advanced Critical Care Volume 22, Number 3, pp.177–182 © 2011, AACN Drug Update Earnest Alexander, PharmD, and Gregory M. Susla, PharmD Department Editors Management of Intracranial Hypertension: Focus on Pharmacologic Strategies Kelly M. Ennis, PharmD Gretchen M. Brophy, PharmD, BCPS hypertension is a medical emergency requiring prompt attention Ithentracranial and intervention to prevent devastating neurologic outcomes. Approaches to management of elevated intracranial pressure (ICP) include pharmacologic and nonpharmacologic strategies, both of which are relevant to the critical care nurse practitioner. The aim of this column is to briefly familiarize the reader with the normal physiology and principles of ICP as well as provide a focused review of pharmacologic strategies to reduce elevated ICP. Mannitol (Osmitrol) and hypertonic saline will be reviewed in detail, including dosing, administration, potential adverse effects, and monitoring issues for each. The role of analgesia and sedation in managing elevated ICP also will be discussed. Finally, the use of barbiturates as well as nonpharmacologic measures will be reviewed briefly. Physiology and Principles of ICP Understanding the basic anatomy and physiology of the central nervous system is paramount to understanding the pathophysiology of intracranial hypertension. The skull is a fixed compartment containing approximately 80% brain tissue, 10% cerebrospinal fluid (CSF), and 10% blood volume.1 The key to understanding the strategies in the management of elevated ICP, both pharmacologic and nonpharmacologic, is the Monroe-Kellie principle. This theory states that the total volume in this system is fixed, and the individual components must compensate if a pathologic process affects the normal quantities of any one of these components; that is, an increase in brain size, blood volume, or CSF must be accompanied by an equal decrease in 1 of these components or an elevation in ICP will occur.1,2 Therefore, reducing ICP may be achieved by 1 or more of the following approaches: reducing brain size (edema) through the use of hyperosmolar therapies, reducing CSF via physical drainage, reducing blood volume by inducing hyperventilation and vasoconstriction, or surgical removal of a space-occupying lesion such as a tumor or hematoma.1 Normal ICP ranges from 5 to 15 mm Hg for adults. Severe intracranial hypertension is considered present at pressures greater than 20 to 25 mm Hg and typically requires some form of treatment.3 Elevated ICP leads to a decrease in cerebral perfusion pressure (CPP) and decreased flow, resulting in cerebral Kelly M. Ennis is PGY2 Critical Care Pharmacy Resident, Department of Pharmacy Services, Virginia Commonwealth University Health System, 401 N 12th St, PO Box 980042, Richmond, VA 23298 ([email protected]). Gretchen M. Brophy is Professor of Pharmacotherapy & Outcomes Science and Neurosurgery, Virginia Commonwealth University, Medical College of Virginia Campus, Richmond, VA. DOI: 10.1097/NCI.0b013e318214564b 177 NCI200147_Layout 1 09/07/11 6:20 PM Page 178 Drug Update A AC N ischemia. Intracranial pressure values consistently greater than 40 mm Hg represent lifethreatening intracranial hypertension because of the risk for brain herniation. Autoregulation allows the brain to maintain adequate cerebral blood flow (CBF) when CPP is in a normal range (50–150 mm Hg).2 In patients with elevated ICP, it may be necessary to maintain a higher MAP as a method to keep CPP approximately 50 to 70 mm Hg. Cerebral perfusion pressure values less than 50 mm Hg have been associated with cerebral ischemia and poor outcomes.1,3 Elevated ICP Elevated ICP or intracranial hypertension may have a variety of etiologies, including a primary or intracranial process, an extracranial process, or it may be a complication of a neurosurgical procedure. Primary or intracranial processes may be a result of a brain lesion (malignant or infectious in nature), neurotrauma, intracerebral hemorrhage, ischemic stroke, or hydrocephalus. Extracranial processes may include airway obstruction, hypoventilation, dysregulation of blood pressure, posture, fever, seizure activity, hepatic failure, or drug toxicity.4 Elevated ICP may also occur after neurosurgical procedures because of hematoma, residual edema, excess vasodilation, or disturbances in CSF.2 Pharmacologic Treatment of Elevated ICP The pharmacologic management of elevated ICP centers mostly around the use of hyperosmolar agents, including mannitol and hypertonic saline. For many years, the mainstay of hyperosmotic therapy for elevated ICP was mannitol, with the use of hypertonic saline becoming more prevalent recently. Several comparative studies have been done with these 2 agents with inconclusive results; no evidence supports one therapy over the other.5–9 Each patient’s clinical scenario should be taken into account when choosing between these hyperosmolar therapies. Mannitol Mannitol is an osmotic diuretic that is most commonly used in the reduction of ICP. Mannitol reduces ICP in 2 ways. First, it expands plasma volume, leading to decreased blood viscosity and increased CBF and oxygen delivery. It also increases serum osmolality, resulting in the creation of an osmotic gradient between the intravascular space and extracel- lular space in the brain. This gradient allows fluid from the cerebral parenchyma to be drawn into the serum, resulting in a reduction in cerebral edema, subsequently reducing ICP. In cases of intracranial hypertension, mannitol is administered via intravenous (IV) bolus over 20 to 30 minutes. The dose ranges from 0.25 to 1.5 g/kg IV as a 20% solution. Doses of 1 g/kg or more are used when an urgent reduction of ICP is necessary. Administration as an IV bolus results in a reduction in ICP in less than 5 minutes, with the peak effect occurring between 15 and 30 minutes after administration. The duration of the reduction in ICP may last from 1.5 to 6 hours, depending on the clinical condition. For patients requiring prolonged reduction in ICP, doses of 0.25 to 1 g/kg may be repeated every 2 to 6 hours.2,3 Although the administration of mannitol may be lifesaving, there are concerns related to the administration and potential adverse effects of this drug. Mannitol is a vesicant or an agent that may cause tissue blistering; therefore, care should be taken to avoid extravasation; administration via central IV access is preferable. This product should be inspected for crystal formation before administration. If crystals are present, the product should be redissolved by warming the solution. Because of the potential for crystal formation, mannitol must be administered through a 5-micron, in-line filter set. Mannitol may not be administered with blood products because of the risk of agglutination or clumping of red blood cells. It is important to monitor patients for adverse effects that may result from the administration of mannitol. Although mannitol draws fluid from the cerebral parenchyma into the intravascular space, it also induces profound diuresis. Intravascular volume depletion as well as electrolyte loss may be induced after administration. Intake and output should be monitored closely, and fluid lost during this process should be replaced. Because of its diuretic effect, mannitol is relatively contraindicated in hypovolemic patients. Other adverse effects that may occur include nephrotoxicity, rebound increases in ICP upon discontinuation, as well as respiratory distress resulting from fluid overload in patients with cardiovascular disease. Mannitol is primarily eliminated in the urine as an unchanged drug; therefore, adverse effects are most likely to be seen in patients with reduced renal function or after repeated administration of high doses. Nephrotoxicity may be prevented 178 NCI200147_Layout 1 09/07/11 6:20 PM Page 179 Drug Update VO L U M E 2 2 • N U M B E R 3 • J U LY – S E P T E M B E R 2 011 by avoiding the use of mannitol in patients with preexisting renal disease or sepsis, by targeting serum osmolality less than 320 mOsm/L, and by avoiding the use of other nephrotoxic medications.3,10,11 Hypertonic Saline Human and animal studies have shown that hypertonic saline possesses the ability to reduce ICP through administration both as a bolus and as a continuous infusion.3,12 Similar to the mechanism of action of mannitol, hypertonic saline reduces ICP through its osmotic effects. Sodium chloride administered in hypertonic concentrations ranging from 3% to 23.4% creates an osmotic gradient that forces fluid (cerebral edema) to the intravascular space, thereby reducing ICP. Bolus doses are usually administered in response to a measured ICP and may be repeated as needed until either the ICP is in an acceptable range or serum sodium concentrations have risen above normal (greater than 145–155 mEq/L).12 Table 1 summarizes various regimens of hypertonic saline that have been studied and may be seen in practice.6,13–16 Limited data also suggest that hypertonic saline administered as a continuous infusion may result in a reduction in ICP. Continuous infusions of 3% hypertonic saline may be titrated to treatment goals including serum sodium of 145 to 155 mEq/L and serum osmolality of 310 to 320 mOsm/L.17,18 Hypertonic saline in concentrations of 3% or more must be administered through central IV access because of its high osmolarity and tonicity. A 3% sodium chloride solution has an osmolarity of 1027 mOsm/L and contains 513 mEq/L of sodium, compared with 0.9% sodium chloride, which has an osmolarity of 308 mOsm/L and contains 154 mEq/L of sodium. The Institute for Safe Medication Practices includes this medication among its list of drugs that may cause significant patient harm when used in error at concentrations greater than 0.9%. The Joint Commission recommends that concentrated electrolyte solutions such as hypertonic saline be obtained from pharmacy services and not be readily available in patient care areas. For this reason, mannitol may be a more convenient option in an urgent clinical situation. Table 1: Evidence-Based Hypertonic Saline Regimens Trial Study Design Regimen ICP Threshold* (mm Hg) Outcome Kerwin et al13 Retrospective review, single center, N ⫽ 22 23.4% sodium chloride solution: 30 mL administered IV over ⱖ30 min ⬎20 HS: ↓ ICP more than mannitol Huang et al14 Prospective, observational, single center, N ⫽ 18 3% sodium chloride solution: 300 mL administered IV over 20 min ⬎20 Rapid infusion of HS is safe to ↓ ICP Ware et al15 Retrospective review, single center, N ⫽ 13 23.4% sodium chloride solution: 30 mL administered IV (Patients included had become tolerant to mannitol.) ⬎20 HS: ↓ ICP comparable to mannitol Vialet et al6 Prospective, randomized, single center, N ⫽ 20 7.5% sodium chloride solution: 2 mL/kg administered IV over 20 min ⬎25 HS: ↓ no. of elevated ICP episodes Munar et al16 Prospective, nonrandomized, single center, N ⫽ 14 7.2% sodium chloride solution: 1.5 mL/kg administered IV over 15 min ⬎15 HS: sig.↓ ICP without sig. change in CBF Abbreviations: CBF, cerebral blood flow; HS, hypertonic saline; ICP, intracranial pressure; IV, intravenous. *ICP Threshold ⫽ ICP at which hypertonic saline was administered in patients included. 179 NCI200147_Layout 1 09/07/11 6:20 PM Page 180 Drug Update A AC N Hypertonic saline may be the osmotic therapy of choice in hypovolemic or hypotensive patients because it remains in the intravascular space, thereby expanding intravascular volume and increasing mean arterial pressure. Despite these positive effects, potentially deleterious effects may result from administering high concentrations of sodium chloride. Hypertonic saline administration has been shown to cause natriuresis secondary to increased renal perfusion pressure and associated diuresis. Despite this natriuretic response, serum sodium increases after the administration of hypertonic saline. Prolonged hypernatremia may result in hypokalemia because of sodium and potassium exchange at the distal tubule of the kidney, as well as nonspecific symptoms such as lethargy, weakness, and in more severe instances seizure or coma. These more severe symptoms may result from abrupt changes in sodium concentrations, such as an increase of greater than 10 to 12 mEq/L in a 24-hour period. Rapid changes in serum sodium concentrations may result in osmotic demyelination syndrome. This syndrome results from a rapid decrease in brain volume in response to a rapid increase in serum sodium. Resulting neurologic changes range from mild confusion that is reversible to severe irreversible disability including seizure or coma.19 Other adverse effects that may result from the administration of hypertonic sodium chloride include hyperchloremic acidosis resulting from excess chloride administration. One strategy to avoid hyperchloremic acidosis is to administer a sodium acetate infusion rather than sodium chloride or a combination of the 2.15,17,20 Other potential complications are cardiovascular and/or respiratory compromise resulting from intravascular fluid overload as well as bleeding. The bleeding risk results from prolongation of prothrombin and activated partial thromboplastin times and decreased platelet aggregation due to an unknown mechanism.21 Further research is necessary to fully understand the process by which this adverse effect occurs. As with mannitol, the risk of rebound intracranial hypertension exists after discontinuation. Important monitoring parameters include strict recording of intake and output, and judicious monitoring of serum electrolytes, and neurologic, cardiovascular, and respiratory status. Analgesia, Sedation, and Neuromuscular Blockade In addition to the methods listed earlier, ICP elevations may be reduced by providing the patient with adequate analgesia, sedation/anxiolysis, and, in some cases, paralysis via neuromuscular blockade. Although there are no randomized controlled trials showing a beneficial effect of these strategies on mortality or Glasgow Outcome Score, it has been shown that controlling pain and agitation significantly reduces ICP and resistance to mechanical ventilation.3,13,22 The neurologic examination may be compromised when patients are under the influence of analgesics and sedatives; therefore, agents with a quick onset and short duration of action are viewed more favorably. Agents commonly chosen for these patients include fentanyl, which has an immediate onset and duration of effect of approximately 30 minutes to 1 hour, and propofol, which has an onset of 1 to 2 minutes and duration of effect of approximately 3 to 10 minutes.23 Barbiturates In addition to the usual sedation and analgesia provided in the intensive care unit environment for a patient with elevated ICP, a barbiturateinduced coma may be considered. Barbiturate coma is typically used only for patients with elevated ICP refractory to other treatment options because of the risks associated with high-dose barbiturates as well as the inability to perform a neurologic assessment on a comatose patient. The mechanism of action of barbiturate coma is severalfold, including reducing the CBF and cerebral metabolic rate of oxygen consumption, resulting in a decreased cerebral blood volume and subsequently reduced ICP.2,3 To date, there is no evidence supporting a beneficial effect of barbiturate coma on outcomes in head injury.3 The most recent comment from the Brain Trauma Foundation regarding the use of barbiturates to control elevated ICP recommends barbiturate therapy in hemodynamically stable patients with severe traumatic brain injury and associated elevation in ICP refractory to maximum medical and surgical treatment.3 The most commonly used barbiturate in this setting is pentobarbital administered IV in a loading dose of 10 mg/kg over 1 to 2 hours followed by additional 5 mg/kg bolus doses as needed with a goal of achieving burst suppression on electroencephalogram. The maintenance dose is then initiated at 1 to 2 mg/kg/h and may be titrated up to a maximum of 4 mg/kg/h in the setting of continuous electroencephalographic technology. Complications related to pentobarbital 180 NCI200147_Layout 1 09/07/11 6:20 PM Page 181 Drug Update VO L U M E 2 2 • N U M B E R 3 • J U LY – S E P T E M B E R 2 011 administration include hypotension, hypokalemia, respiratory depression, infections, and hepatic and renal dysfunction. Barbiturates as a pharmacologic class cause widespread suppression of all excitable tissue, including the central nervous system. This central nervous system depression may range from calmness and sleep to unconsciousness and coma, which may progress in a dose-dependent fashion to respiratory and cardiovascular depression if left unmonitored. For this reason, patients receiving continuous barbiturate therapy must be mechanically ventilated and undergo continuous cardiac monitoring. The risk for rebound intracranial hypertension exists after discontinuation of pentobarbital; therefore, the weaning process should take place slowly, with the rate of administration decreased by one-half over each 24-hour period until discontinued.2,3 Nonpharmacologic Management of Elevated ICP Nonpharmacologic measures may be used to assist in reducing ICP in addition to drug therapy. These include positional strategies, airway and ventilation manipulation, surgical management, and potentially hypothermia. To maximize outflow of CSF from the intracranial compartment to the spinal compartment minimizing ICP, keep the head of the patient’s bed elevated at 30⬚.2 After the airway has been secured, if ICP ⬍20 mm Hg, ventilator settings should allow a slight hyperventilation with a target PaCO2 of approximately 35 mm Hg. This reduction in PaCO2 increases the serum pH and, in turn, the pH of the CSF. This produces arterial vasoconstriction, which increases cerebral vascular resistance resulting in reduced CBF, cerebral blood volume, and ICP.1 Hyperventilation may become more aggressive, with a target PaCO2 between 30 and 35 mm Hg if elevated ICP persists despite other interventions. An additional option for patients with refractory intracranial hypertension is the use of decompressive craniectomy to relieve ICP.1–3 The use of therapeutic hypothermia (goal core body temperature of 33°C) in the management of elevated ICP is somewhat controversial. Although hypothermia has been shown to be effective in reducing ICP, it is unclear whether these patients have improved neurologic outcomes after rewarming.3 Therapeutic hypothermia is not a benign process and has an effect on the body’s metabolic processes, including drug metabolism.24 It is important to understand that the metabolism of drugs may be impaired in these patients, resulting in elevated circulating drug concentrations. This is especially true of medications whose primary route of metabolism is hepatic (eg, fentanyl, midazolam, phenytoin, propofol). Limited data exist surrounding the specific pharmacokinetic profiles of drugs used in the hypothermic patient; therefore, specific recommendations for dose adjustments are not available. Discussion Prolonged intracranial hypertension results in compromised CPP and subsequent cerebral ischemia. Health care providers must understand the various strategies used to manage elevated ICP, including hyperosmolar therapy, sedatives, and analgesics, as well as barbiturate coma. The agents used for hyperosmotic therapy are mannitol and hypertonic saline, which both act by creating an osmotic gradient between the intracranial and intravascular spaces. Mannitol is limited by its potential for nephrotoxicity when administered to a patient with serum osmolality more than 320 mOsm/L. Administration of hypertonic saline is limited by both serum sodium and serum chloride levels after repeated doses. Both agents carry a risk of rebound intracranial hypertension upon discontinuation. Adequate analgesia and sedation have been shown to be beneficial in assisting with reduction of ICP. Barbiturate comas are typically reserved for patients with intracranial hypertension refractory to all other available medical and surgical management. Nonpharmacologic measures are also used in the management of elevated ICP, including elevation of the head of bed, hyperventilation, surgical intervention, and potentially hypothermia. Understanding the benefits and risks of these therapies is imperative to optimally manage the patient with elevated ICP. REFERENCES 181 1. Vincent JL, Berré J. Primer on medical management of severe brain injury. Crit Care Med. 2005;33:1392–1399. 2. Rangel-Castillo L, Robertson C. Management of intracranial hypertension. Crit Care Clin. 2007;22:713–732. 3. Brain Trauma Foundation. Guidelines for the management of severe traumatic brain injury, 3rd ed. J Neurotrauma. 2007;24(suppl 1):S1–S106. 4. Stravitz RT. Critical management decisions in patients with acute liver failure. Chest. 2008;134(5):1092–1102. 5. Battison C, Andrew PJD, Graham C, et al. Randomized, controlled trial on the effect of a 20% mannitol solution and a 7.5% saline/6% dextran solution on increased intracranial pressure after brain injury. Crit Care Med. 2005;33:196–202. 6. Vialet R, Albanese J, Thomachot L, et al. Isovolume hypertonic solutes (sodium chloride or mannitol) in the treatment NCI200147_Layout 1 09/07/11 6:20 PM Page 182 Drug Update 7. 8. 9. 10. 11. 12. 13. 14. 15. A AC N of posttraumatic intracranial hypertension: 2 mL/kg 7.5% saline is more effective than 2 mL/kg 20% mannitol. Crit Care Med. 2003;31:1683–1687. Cooper DJ, Myles PS, Mcdermott FT, et al. Prehospital hypertonic saline resuscitation of patients with hypotension and severe traumatic brain injury: a randomized controlled trial. JAMA. 2004;291:1350–1357. White H, Cook D, Venkatesh B. The use of hypertonic saline for treating intracranial hypertension after traumatic brain injury. Anesth Analg. 2006;102:1836–1846. De Vivo O, Del Gaudio A, Ciritella P, et al. Hypertonic saline solution: a safe alternative to mannitol 18% in neurosurgery. Minerva Anesthesiol. 2001;67:603–611. Gondim FA, Aiyagari V, Shackleford A. Osmolality not predictive of mannitol-induced acute renal insufficiency. J Neurosurg. 2005;103:444–447. Rabetoy GM, Fredericks MR, Hostettler CF. Where the kidney is concerned, how much mannitol is too much? Ann Pharmacother. 1993;27:25–28. Doyle JA, Davis DP, Hoyt DB. The use of hypertonic saline in the treatment of traumatic brain injury. J Trauma. 2001;50:367–383. Kerwin AJ, Schinco MA, Tepas JJ III, et al. The use of 23.4% hypertonic saline for the management of elevated intracranial pressure in patients with severe traumatic brain injury: a pilot study. J Trauma. 2009;67:277–282. Huang SJ, Chang L, Han Y, et al. Efficacy and safety of hypertonic saline solutions in the treatment of severe head injury. Surg Neurol. 2006;65:539–546. Ware ML, Nemani VM, Meeker M, et al. Effects of 23.4% sodium chloride solution in reducing intracranial pressure in patients with traumatic brain injury: a preliminary study. Neurosurgery. 2005;57:727–736. 16. Munar F, Ferrer AM, de Nadal M, et al. Cerebral hemodynamic effects of 7.2% hypertonic saline in patients with head injury and raised intracranial pressure. J Neurotrauma. 2000;17:41–51. 17. Qureshi AI, Suarez JI, Castro A, et al. Use of hypertonic saline/acetate infusion in treatment of cerebral edema in patients with head trauma: experience at a single center. J Trauma. 1999;47:659–665. 18. Qureshi AI, Suarez JI, Bhardwaj A, et al. Use of hypertonic (3%) hypertonic saline/acetate infusion in the treatment of cerebral edema: effect on intracranial pressure and lateral displacement of the brain. Crit Care Med. 1999;26:440–446. 19. Sterns RH, Riggs JE, Schochet SS, et al. Osmotic demyelination syndrome following correction of hyponatremia. N Engl J Med. 1986;314:1535–1542. 20. Qureshi AI, Suarez JI. Use of hypertonic saline solutions in treatment of cerebral edema and intracranial hypertension. Crit Care Med. 2000;28:3301–3313. 21. Reed RL II, Johnston TD, Chen Y, et al. Hypertonic saline alters plasma clotting times and platelet aggregation. J Trauma. 1991;31:8–14. 22. Kelly PF, Goodale DB, Williams J, et al. Propofol in the treatment of moderate and severe head injury: a randomized, prospective double-blinded pilot trial. J Neurosurg. 1999;90:1042–1057. 23. Jacobi J, Fraser GL, Coursin DB, et al. Clinical practice guidelines for the sustained use of sedatives and analgesics in the critically ill adult. Crit Care Med. 2002;30:119–141. 24. Henderson WR, Dhingra VK, Chittock DR, et al. Hypothermia in the management of traumatic brain injury: a systematic review and meta-analysis. Intensive Care Med. 2003;29:1637–1644. 182 NCI200162_Layout 1 16/07/11 2:30 AM Page 183 AACN Advanced Critical Care Test writer: Jane Baron, RN, CS, ACNP Contact hour: 1.0 Synergy CERP: Category A Passing score: 9 correct (75%) DOI: 10.1097/NCI.0b013e31822bb822 CE Test Instructions To receive CE credit for this test (ID# ACC223), mark your answers on the form below, complete the enrollment information and submit it with the $10 processing fee (nonmembers only; payable in US funds) to the American Association of Critical-Care Nurses (AACN). Answer forms must be postmarked by July 1, 2013. Within 6 weeks of AACN’s receiving your test form, you will receive an AACN CE certificate. The American Association of Critical-Care Nurses (AACN) is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center’s Commission on Accreditation. AACN has been approved as a provider of continuing education in nursing by the State Boards of Nursing of Alabama (#ABNP0062), California (#01036), and Louisiana (#ABN12). AACN programming meets the standards for most other states requiring mandatory continuing education credit for relicensure. CE Test Form Test ID#: ACC223 FORM EXPIRES July 1, 2013 Fee: $10 (no fee for members of AACN) Management of Intracranial Hypertension: Focus on Pharmacologic Strategies Mark your answers clearly in the appropriate box. There is only one correct answer per question. You may photocopy this form. 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Date _________ Signature____________________________________________________ Program Evaluation Objective 1 was met Objective 2 was met Objective 3 was met The content was appropriate My expectations were met This method of CE is effective for this content Yes ❍ No ❍ ❍ ❍ ❍ ❍ ❍ ❍ ❍ ❍ ❍ ❍ The level of difficulty of this test was: ❍ easy ❍ medium ❍ difficult To complete this program, it took me ____________ hours/minutes. Mail to: AACN 101 Columbia Aliso Viejo, CA 92656 183 Or fax to 949-362-2021 Or take test online at www.aacn.org>ContinuingEducation NCI200162_Layout 1 16/07/11 2:30 AM Page 184 CE Test Questions Management of Intracranial Hypertension: Focus on Pharmacologic Strategies Objectives: 1. Review physiology and principles of intracranial pressure (ICP). 2. Examine pharmacologic treatment of elevated ICP. 3. Describe 3 nonpharmacologic treatment modes for elevated ICP. 1. Which statement correctly outlines the Monroe-Kellie principle? a. Increase of brain size must be accompanied by decrease in cerebrospinal fluid (CSF) or blood volume to prevent increased ICP. b. Increase of brain size must be accompanied by decrease in CSF or blood volume to cause increased ICP. c. Increase of blood volume must be accompanied by increase in CSF or brain size to prevent increased ICP. d. Increase of CSF must be accompanied by decrease in brain size or blood volume to cause increased ICP. 7. Which statement is true? a. Mannitol reduces ICP by increasing serum osmolarity and expanding plasma volume. b. To reduce ICP, mannitol is administered as a continuous IV drip. c. Mannitol is safest given through peripheral IV lines. d. Crystal formation from mannitol can be resolved by refrigerating the solution. 8. What are two adverse effects of mannitol administration? a. Hepatotoxicity and extravascular volume depletion b. Nephrotoxicity and respiratory distress c. Intravascular volume depletion and gastroparesis d. Cardiotoxicity and sepsis 2. Which ICP reading could cause a decrease in cerebral perfusion pressure (CPP)? a. 4 mm Hg b. 9 mm Hg c. 14 mm Hg d. 24 mm Hg 9. What is the advantage of using hypertonic saline over mannitol? a. Mannitol can only be given as an IV infusion. b. Hypertonic saline solution of 3% can be given peripherally. c. Mannitol’s effect lasts only 30 minutes. d. Hypertonic saline possesses the ability of lowering ICP through bolus and continuous IV infusion. 3. What is the normal range of CPP? a. 25-50 mm Hg b. 50-150 mm Hg c. 150-200 mm Hg d. 200-300 mm Hg 4. What CPP level is associated with cerebral ischemia? a. 25-50 mm Hg b. 50-150 mm Hg c. 150-200 mm Hg d. 200-300 mm Hg 10. What syndrome results from rapid decrease in brain volume in response to rapid increase in serum sodium? a. Decreasing ICP syndrome b. Hypertonic saline syndrome c. Osmotic demyelination syndrome d. Displacement syndrome 5. Which of the following is not a potential cause of elevated ICP? a. Brain lesion b. Intracerebral hemorrhage c. Airway obstruction d. Myocardial infarction 11. Which medications are used to provide adequate analgesia and sedation of short duration? a. Pentobarbital and valium b. Mannitol and fentanyl c. Hypertonic saline and valium d. Fentanyl and propofol 6. Which statement is true? a. Primary processes that increase ICP are hypoventilation and fever. b. Extracranial processes that increase ICP include ischemic stroke and hydrocephalus. c. Neurosurgical procedures can increase ICP if hematoma or excess vasodilation occurs. d. Hepatitis C is a major cause of increased ICP. 12. Which of the following nonpharmacologic measures will increase ICP? a. Hyperthermia b. Decompressive craniectomy c. Head of bed at 30 degrees d. Hyperventilation with target PaCO2 of 30 mm Hg 184
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