neurologic disorders
Overview of Coma and Impaired Consciousness
Treatment
Immediate stabilization (airway, breathing, circulation, or ABCs) Admission to an intensive care unit (ICU) Supportive measures, including, when necessary, control of ICP Treatment of underlying disorder Airway, breathing, and circulation must be ensured immediately. Treatment must be corrected. Patients with impaired consciousness are admitted to the ICU so that respiratory and neurologic status can be monitored. If hypertension is present, blood pressure should be reduced carefully; lowering blood pressure below the patient's usual level can lead to brain ischemia. Because some patients in coma are undernourished and susceptible to Wernicke Encephalopathy , thiamin 100 mg IV or IM should be given routinely. If plasma glucose is low, patients should be given 50 mL of 50% If trauma is involved, the neck is immobilized until CT is done to rule out damage to the cervical spine. Some patients in a stupor or coma after head trauma benefit from treatment with drugs that can improve nerve cell function (eg,amantadine). Such treatment lead to improvement in neurologic responsiveness for as long as the drug is continued. However, such treatment may not make any difference in improvement over the long term. If opioid overdose is suspected,naloxone2 mg IV is given and repeated as necessary. If a recent (within about 1 hour) overdose of certain drugs is possible, Gastric emptying (with airway protection) can be done through a large-bore orogastric tube (eg, ≥ 32 Fr) after endotracheal intubation. Coexisting disorders and abnormalities are treated as indicated. For example, metabolic abnormalities are corrected. Core body temperature may need to be corrected (eg, cooling for severe hyperthermia, warming for hypothermia). Patients with any of the following require Tracheal Intubation to prevent aspiration and ensure adequate ventilation: Infrequent, shallow, or stertorous respirations Low oxygen saturation (determined by pulse oximetry or ABG measurements) Impaired airway reflexes Severe unresponsiveness (including most patients with a Glasgow Coma Scale score≤8) If increased ICP is suspected, intubation should be done via rapid-sequence oral intubation (using a paralytic drug) rather than via nasotracheal intubation; nasotracheal intubation in a patient who is breathing spontaneously causes more coughing and gagging, thus increasing ICP, which is already increased because of intracranial abnormalities. To minimize the increase in ICP that may occur when the airway is manipulated, some clinicians recommend givinglidocaine1.5 mg/kg IV 1 to 2 minutes before giving the paralytic. Patients are sedated before the paralytic is given.Etomidateis a good choice in hypotensive or trauma patients because it has minimal effects on blood pressure; IV dose is 0.3 mg/kg for adults (or 20 mg for an average-sized adult) and 0.2 to 0.3 mg/kg for children. Alternatively, if hypotension is absent and unlikely and ifpropofolis readily available,propofol0.2 to 1.5 mg/kg may be used. Succinylcholine1.5 mg/kg orrocuronium1 mg/kg IV is typically used as a paralytic. Paralytics should be used only when they are deemed necessary for intubation and needed to avoid further increases in ICP. Otherwise, paralytics should be avoided because rarely, drugs such assuccinylcholinecan lead to malignant hyperthermia and can mask neurologic findings and changes. Pulse oximetry and ABGs (if possible, end-tidal CO2) should be used to assess adequacy of oxygenation and ventilation. If intracranial pressure (ICP) is increased, clinicians should monitor intracranial and cerebral perfusion pressure, and pressures should be controlled. The goal is to maintain ICP at≤20 mm Hg and cerebral perfusion pressure at 50 to 70 mm Hg. ICP is usually lower in children than in adults. In neonates, ICP can be below the atmospheric pressure. Thus, children are evaluated independently from adult guidelines. Control of increased ICP involves several strategies: Sedation:Sedatives may be necessary to control agitation, excessive muscular activity (eg, due to delirium), or pain, which can increase ICP.Propofolis often used in adults (contraindicated in children) because onset and duration of action are quick; dose is 0.3 mg/kg/hour by continuous IV infusion, titrated gradually up to 3 mg/kg/hour as needed. An initial bolus is not used. The most common adverse effect is hypotension. Prolonged use at high doses can cause pancreatitis. Benzodiazepines (eg,midazolam,lorazepam) can also be used. Because sedatives can mask neurologic findings and changes, their use should be minimized and, whenever possible, avoided. Antipsychotics should be avoided if possible because they can delay recovery. Sedatives are not used to treat agitation and delirium due to hypoxia; oxygen is used instead. 25 mm Hg should be avoided because it may reduce cerebral blood flow excessively and result in cerebral ischemia. Other Increased intracranial pressure may be used. Hydration:Isotonic fluids are used. Providing free water through IV fluids (eg, 5%dextrose, 0.45% saline) can aggravate cerebral edema and should be avoided. Fluids may be restricted to some degree, but patients should be kept euvolemic. If patients have no signs of dehydration or fluid overload, IV fluids with normal saline can be started at 50 to 75 mL/hour. The rate can be increased or decreased based on serum sodium, osmolality, urine output, and signs of fluid retention (eg, edema). Diuretics:Serum osmolality should be kept at 295 to 320 mOsm/kg. Osmotic diuretics (eg,mannitol) may be given IV to lower ICP and maintain serum osmolality. These drugs do not cross the blood-brain barrier. They pull water from brain tissue across an osmotic gradient into plasma, eventually leading to equilibrium. Effectiveness of these drugs decreases after a few hours. Thus, they should be reserved for patients whose condition is deteriorating (eg, those with acute brain herniation) or used preoperatively for patients with hematomas.Mannitol20% solution is given 0.5 to 1 g/kg IV (2.5 to 5 mL/kg) over 15 to 30 minutes, then given as often as needed (usually every 6 to 8 hours) in a dose ranging from 0.25 to 0.5 g/kg (1.25 to 2.5 mL/kg).Mannitolmust be used cautiously in patients with severe coronary artery disease, heart failure, renal insufficiency, or pulmonary vascular congestion becausemannitolrapidly expands intravascular volume. Because osmotic diuretics increase renal excretion of water relative to sodium, prolonged use ofmannitolmay result in water depletion and hypernatremia.Furosemide1 mg/kg IV can decrease total body water, particularly when transient hypervolemia associated withmannitolis to be avoided. Fluid and electrolyte balance should be monitored closely while osmotic diuretics are used. A 3% saline solution is another potential osmotic agent to control ICP. Blood pressure (BP) control:Systemic antihypertensives are needed only when hypertension is severe (>180/95 mm Hg). How much BP is reduced depends on the clinical context. Systemic BP needs to be high enough to maintain cerebral perfusion pressure even when ICP increases. Hypertension can be managed by titrating anicardipinedrip (5 mg/hour, increased by 2.5 mg every 5 minutes to a maximum of 15 mg/hour) or by boluses oflabetalol(10 mg IV over 1 to 2 minutes, repeated every 10 minutes to a maximum of 150 mg). Corticosteroids:Corticosteroids are useful for treating vasogenic brain edema. Vasogenic edema results from disruption of the blood-brain barrier, which may occur in patients with a brain tumor. Cytotoxic edema results from cell death and breakdown, which may occur in patients with stroke, cerebral hemorrhage, or trauma; it may also occur after hypoxic brain damage due to cardiac arrest. Treatment with corticosteroids is effective only for tumors and sometimes abscesses of the brain when vasogenic edema is present. Corticosteroids are ineffective for cytotoxic edema and can increase plasma glucose, exacerbating cerebral ischemia and complicating management of diabetes mellitus. For patients without brain ischemia, an initial dose ofdexamethasone20 to 100 mg, followed by 4 mg once a day appears to be effective while minimizing adverse effects.Dexamethasonecan be given IV or orally. Removal of cerebrospinal fluid (CSF):CSF can be slowly removed through a shunt inserted into the ventricles to help lower increased ICP. CSF is removed at a rate of 1 to 2 mL/minute for 2 to 3 minutes. Continuous drainage of CSF (eg, through a lumbar drain) should be avoided because it may lead to brain herniation. Position: Positioning the patient to maximize venous outflow from the head can help minimize increases in ICP. The head of the bed can be elevated to 30° (with the head above the heart) as long as cerebral perfusion pressure remains at the desired range. The patient’s head should be kept in a midline position, and neck rotation and flexion should be minimized. Tracheal suctioning, which can increase ICP, should be limited. If ICP continues to increase despite other measures to control it, the following may be used: When ICP is increased after head trauma or cardiac arrest, hypothermia in the range of 32 to 35° C has been used to reduce ICP to < 20 mm Hg. However, use of hypothermia to lower ICP is controversial; some evidence suggests that this treatment may not effectively lower ICP in adults or children and may have adverse effects ( Treatment references ). Pentobarbitalcoma:Pentobarbitalcan reduce cerebral blood flow and metabolic demands. However, its use is controversial because the effect on clinical outcome is not consistently beneficial, and treatment withpentobarbitalcan lead to complications (eg, hypotension). In some patients with refractory intracranial hypertension that does not respond to standard hyperventilation and hyperosmolar therapy,pentobarbitalcan improve functional outcome. Coma is induced by givingpentobarbital10 mg/kg IV over 30 minutes, followed by 5 mg/kg/hour for 3 hours, then 1 mg/kg/hour. The dose may be adjusted to suppress bursts of EEG activity, which is continuously monitored. Hypotension is common and is managed by giving fluids and, if necessary, vasopressors. Other possible adverse effects include arrhythmias, myocardial depression, and impaired uptake or release of potentially neurotoxic glutamate in the brain. Craniotomy with duraplasty can be done to provide room for brain swelling. This procedure can prevent deaths, but overall functional outcome may not improve much, and it may lead to complications such as hydrocephalus in some patients ( Treatment references ). It may be most useful for large cerebral infarcts with impending herniation, particularly in patients Patients require meticulous long-term care. Stimulants, sedatives, and opioids should be avoided. Enteral Tube Nutrition is started with precautions to prevent aspiration (eg, elevation of the head of the bed); a percutaneous endoscopic jejunostomy tube is placed if necessary. Early, vigilant attention to skin care, including checking for breakdown especially at pressure points, is required to prevent Prevention . Patients require frequent turning and position changes to prevent pressure ulcers, but the head should be kept elevated. Special air mattresses may help manage pressure ulcers. Topical ointments to prevent desiccation of the eyes are beneficial. Passive range-of-motion exercises done by physical therapists and taping or dynamic flexion splitting of the extremities may prevent contractures. Initiating physical therapy early can improve functional outcome in patients with polyneuropathy and myopathy. Measures are also taken Prevention and 1.Moler FW, Silverstein FS, Holubkov R, et al: Therapeutic hypothermia after in-hospital cardiac arrest in children.N Engl J Med376 (4):318-329, 2017. doi: 10.1056/NEJMoa1610493 2.Su TM, Lan CM, Lee TH, et al: Risk factors for the development of posttraumatic hydrocephalus after unilateral decompressive craniectomy in patients with traumatic brain injury.J Clin Neurosci63:62–67, 2019. doi: 10.1016/j.jocn.2019.02.006 Epub 2019 Mar 1. 