Anesthesia for Acute Head Injury
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What is the estimated number of acute head injuries that occur every year in the United States?

  • 2 million
  • 500,000
  • 3 million
  • 1.5 million (correct)

    • What is the primary objective for induction and maintenance of anesthesia in the context of acute head injury?

  • To induce respiratory failure and decrease oxygenation
  • To decrease elevated intracranial pressure and optimize cerebral perfusion (correct)
  • To induce hypotension and decrease cardiac output
  • To increase intracranial pressure and reduce cerebral perfusion

    • What percentage of patients presenting for craniotomy for acute head injury exhibit pupillary abnormalities?

  • 30% to 40%
  • 40% to 50%
  • 10% to 20%
  • 20% to 30% (correct)

    • What is the typical location of epidural hematomas in adults?

    <p>Temporoparietal and temporal regions</p> Signup and view all the answers

    What is a major contributor to poor outcomes after acute brain injury?

    <p>Hypotension with systolic blood pressure ≤100 mm Hg</p> Signup and view all the answers

    What is a common cardiovascular response observed in the compensatory stage of acute head injury?

    <p>Tachycardia and increased cardiac output</p> Signup and view all the answers

    What is a common respiratory response observed in acute head injury?

    <p>Hyperventilation and apnea</p> Signup and view all the answers

    What is a potential consequence of substantial blood loss and/or a progressive or irreversible stage of injury?

    <p>Hypotension and decreased cardiac output</p> Signup and view all the answers

    What is the primary consequence of increased ICP on cerebral function?

    <p>Diffuse and profound hypoperfusion and hypometabolism</p> Signup and view all the answers

    What is the primary cause of cerebral ischemia after acute brain injury?

    <p>Acute brain swelling and cerebral edema</p> Signup and view all the answers

    What is the key factor in deciding whether to perform a craniotomy for AHI?

    <p>Glasgow Coma Score (GCS) and pupillary examination</p> Signup and view all the answers

    What is the primary consequence of loss of cerebral autoregulation after acute brain injury?

    <p>Decreased CBF and CMRO2</p> Signup and view all the answers

    What is the primary mechanism of cell death after acute brain injury?

    <p>Oxidative stress and inflammation</p> Signup and view all the answers

    The scalp incision during a frontotemporal craniotomy begins posterior to the tragus and continues superiorly in a straight line to the frontal area.

    <p>False</p> Signup and view all the answers

    The skull is punctured using a surgical scalpel at the temporal site.

    <p>False</p> Signup and view all the answers

    The anterior burr hole is placed below the frontal sinus.

    <p>False</p> Signup and view all the answers

    A drain is always placed and extends through the same incision as the surgical site.

    <p>False</p> Signup and view all the answers

    The bone flap is always reapplied at the time of surgical closure regardless of the degree of cerebral edema.

    <p>False</p> Signup and view all the answers

    An ICP monitor is always placed at the beginning of surgery to monitor intraoperative ICP.

    <p>False</p> Signup and view all the answers

    What is the primary concern for patients with AHI undergoing craniotomy regarding their airway?

    <p>Partial or complete airway obstruction caused by the tongue blocking the posterior pharyngeal space</p> Signup and view all the answers

    When is rapid sequence induction with in-line neck manual axial stabilization appropriate for patients with AHI?

    <p>When the patient is found to be hemodynamically stable</p> Signup and view all the answers

    What is the target PaCO2 level for mechanical ventilation in patients with AHI undergoing craniotomy?

    <p>35 mm Hg</p> Signup and view all the answers

    When is hypoventilation instituted in patients with AHI undergoing craniotomy?

    <p>When cerebral edema is extreme</p> Signup and view all the answers

    What is the consequence of intubation in patients with AHI undergoing craniotomy?

    <p>An elevation in blood pressure and ICP</p> Signup and view all the answers

    What is the rationale for administering a nondepolarizing muscle relaxant after securing the airway in patients with AHI?

    <p>To facilitate mechanical ventilation and reduce ICP</p> Signup and view all the answers

    What is the primary objective for induction and maintenance of anesthesia in a patient presenting for craniotomy resulting from acute head injury?

    <p>Decrease ICP, optimize cerebral perfusion and oxygenation, and avoid secondary injury</p> Signup and view all the answers

    Which medication is relatively contraindicated in patients with increased ICP due to its sympathomimetic action?

    <p>Ketamine</p> Signup and view all the answers

    What is the effect of inhalation agents on CBF and ICP?

    <p>Increase CBF and ICP</p> Signup and view all the answers

    What is the role of dexmedetomidine in induction of anesthesia in patients with acute head injury?

    <p>To preserve existing blood pressure</p> Signup and view all the answers

    What is the effect of propofol on ICP, CMRO, CBF, and brain metabolism?

    <p>Decreases ICP, CMRO, CBF, and brain metabolism</p> Signup and view all the answers

    What is a beneficial effect of ketamine administration in patients with acute head injury?

    <p>Antagonizes N-methyl-D-aspartate (NMDA) receptors</p> Signup and view all the answers

    What is the recommended concentration of inhalation agents to minimize their negative effects on ICP?

    <p>≤ 1 MAC</p> Signup and view all the answers

    What is the mechanism by which etomidate decreases ICP?

    <p>Decreases CMRO, CBF, and brain metabolism</p> Signup and view all the answers

    What is the formula for calculating cerebral perfusion pressure (CPP)?

    <p>CPP = MAP - ICP</p> Signup and view all the answers

    What is the normal range for cerebral perfusion pressure (CPP)?

    <p>80-100 mm Hg</p> Signup and view all the answers

    What is the effect of increased ICP on cerebral blood flow (CBF)?

    <p>It decreases CBF</p> Signup and view all the answers

    What is the ideal CPP for patients with increased ICP?

    <p>80-100 mm Hg</p> Signup and view all the answers

    What is the effect of hyperventilation on CBF?

    <p>It decreases CBF</p> Signup and view all the answers

    What is the recommended PaCO2 level for hyperventilation?

    <p>25-30 mm Hg</p> Signup and view all the answers

    What is the effect of mannitol administration on CBF?

    <p>It increases CBF</p> Signup and view all the answers

    What is the maximum serum osmolarity level recommended during mannitol administration?

    <p>320 mOm/L</p> Signup and view all the answers

    What is the optimal degree of head elevation to facilitate cerebral venous and CSF drainage and reduce ICP?

    <p>30 degrees</p> Signup and view all the answers

    What is the recommended serum sodium level threshold beyond which hypertonic saline should not be administered?

    <p>160 mEq/L</p> Signup and view all the answers

    What is the primary goal of fluid resuscitation in patients undergoing craniotomy for acute brain injury?

    <p>Maintain CPP &gt; 60 mm Hg</p> Signup and view all the answers

    Why should glucose-containing solutions be avoided in acute brain-injured patients undergoing craniotomy?

    <p>They cause hyperglycemia, leading to poor neurologic outcomes</p> Signup and view all the answers

    What is the recommended crystalloid solution for rapid infusion to restore intravascular volume in patients undergoing craniotomy for acute brain injury?

    <p>Isotonic normal saline</p> Signup and view all the answers

    What is the importance of monitoring coagulation status in patients with acute head injury?

    <p>To guide blood transfusions and fluid resuscitation</p> Signup and view all the answers

    What is the recommended threshold for considering blood transfusion in patients with acute brain injury?

    <p>Hematocrit &lt; 30%</p> Signup and view all the answers

    What is the consequence of severe flexing or turning of the head in patients undergoing craniotomy for acute brain injury?

    <p>Increased ICP</p> Signup and view all the answers

    Where is the optimal location for placing a CVP catheter if the patient has a possible risk for venous air embolism (VAE) during surgery?

    <p>Subclavian vein</p> Signup and view all the answers

    What is the purpose of Doppler ultrasound during craniotomy?

    <p>To monitor for venous air embolism (VAE)</p> Signup and view all the answers

    What is a potential complication in the postoperative period after craniotomy for AHI?

    <p>Seizures</p> Signup and view all the answers

    What is the treatment for a patient demonstrating postoperative seizures after craniotomy for AHI?

    <p>Administering a loading dose of phenytoin 1 g intravenously</p> Signup and view all the answers

    What is the optimal location for the tip of the CVP catheter in the heart?

    <p>Right atrium-superior vena cava junction</p> Signup and view all the answers

    What is the purpose of placing the patient's head 10 cm above the midthorax during craniotomy for AHI?

    <p>To reduce the risk of venous air embolism (VAE)</p> Signup and view all the answers

    What is the recommended treatment for a patient with postoperative hematoma after craniotomy for AHI?

    <p>Administering fresh frozen plasma and platelets</p> Signup and view all the answers

    What is the primary objective of postoperative care for a patient undergoing craniotomy for AHI?

    <p>To maintain a CPP of 60-70 mm Hg</p> Signup and view all the answers

    What is the recommended management for a patient with metabolic or electrolyte disturbances after craniotomy for AHI?

    <p>Obtaining postoperative electrolytes and correcting imbalances</p> Signup and view all the answers

    What is the purpose of continuous ventilatory support in the intensive care unit for a patient undergoing craniotomy for AHI?

    <p>To support respiratory function and maintain adequate oxygenation</p> Signup and view all the answers

    What is the primary mechanism by which hypothermia reduces ICP in patients with acute head injury?

    <p>By suppressing excitatory neurotransmitters</p> Signup and view all the answers

    What is the consequence of hyperthermia on neurologic outcomes in patients with acute head injury?

    <p>It is associated with poor neurologic outcomes</p> Signup and view all the answers

    What is the primary purpose of inserting a CVP catheter intraoperatively for a craniotomy for AHI?

    <p>To measure central venous pressure</p> Signup and view all the answers

    What is the recommended placement of the intraarterial transducer to improve accuracy?

    <p>At the level of the tragus of the ear at the external auditory canal</p> Signup and view all the answers

    What is the benefit of controlled hypothermia for cerebral protection in patients with acute head injury?

    <p>It reduces metabolic demand and suppresses excitatory neurotransmitters</p> Signup and view all the answers

    What is the primary concern regarding the use of hypothermia to reduce ICP in patients with acute head injury?

    <p>It may cause hypotension and cardiac arrhythmias</p> Signup and view all the answers

    What is the effect of hypothermia on CMRO2 in patients with acute head injury?

    <p>It decreases CMRO2 by 7% per degree Celsius</p> Signup and view all the answers

    What is the primary reason why hypothermia is not routinely recommended for reducing ICP in patients with acute head injury?

    <p>It has significant side effects, including coagulopathy and pneumonia</p> Signup and view all the answers

    Which of the following signs is NOT typically associated with increased ICP?

    <p>Tachycardia</p> Signup and view all the answers

    A patient with increased ICP is likely to exhibit which of the following respiratory patterns?

    <p>Irregular respirations</p> Signup and view all the answers

    Which of the following is a late sign of increased ICP?

    <p>Papilledema</p> Signup and view all the answers

    Which of the following is a common ocular finding in patients with increased ICP?

    <p>Unilateral pupillary dilation</p> Signup and view all the answers

    What is the primary consequence of increased ICP on cerebral function?

    <p>Impaired cerebral autoregulation</p> Signup and view all the answers

    Study Notes

    Craniotomy for Acute Head Injury

    • 1.5 million acute head injuries (AHIs) occur every year in the United States, often caused by motor vehicle accidents, sports injuries, and falls.

    Anesthesia Objectives

    • Primary objectives for induction and maintenance of anesthesia: decrease elevated intracranial pressure (ICP), optimize cerebral perfusion and oxygenation, and avoid secondary injury from hypoxia and hypotension.

    Hypotension and Outcomes

    • Hypotension with systolic blood pressure ≤100 mm Hg is a major contributor to poor outcomes after acute brain injury.

    Pupillary Abnormalities

    • Pupillary abnormalities (size, light reflex, and symmetry) occur in 20%-30% of patients presenting for craniotomy for AHI.

    Epidural Hematoma

    • Epidural hematoma: a focal brain injury caused by direct mechanical impact and acceleration-deceleration stress onto the skull and brain tissue, resulting in skull fractures and intracranial lesions.
    • Often caused by skull fracture and laceration of the middle meningeal artery or anterior cerebral artery, allowing bleeding between the skull and dura.
    • Commonly located in the temporoparietal and temporal regions of the brain in adults.

    Physiologic Compensatory Mechanisms

    • Multitude of physiologic compensatory mechanisms initiated to increase cerebral perfusion.
    • Cardiovascular responses: tachycardia, hypertension, and increased cardiac output.
    • Respiratory responses: apnea and abnormal respiratory patterns, respiratory insufficiency, and hyperventilation.

    Cerebral Blood Flow and Metabolism

    • Decreased cerebral blood flow (CBF) and cerebral metabolic rate of oxygen consumption (CMRO2) in the core area of injury.
    • Increased ICP leads to diffuse and more profound hypoperfusion and hypometabolism of the brain.

    Acute Brain Swelling and Cerebral Edema

    • Acute brain swelling and cerebral edema develop concomitantly after acute brain injury, decreasing CBF and resulting in cerebral ischemia.
    • Cerebrovascular autoregulation impaired.

    Decision to Perform Craniotomy

    • Decision to perform craniotomy based on patient's Glasgow Coma Score (GCS), pupillary examination, associated comorbidities, CT scan findings, and ICP values.

    Secondary Neurologic Insults

    • Secondary neurologic insults: blood-brain barrier disruption, loss of cerebral autoregulation, release of inflammatory and excitatory mediators, and oxidative stress leading to cell death.

    Surgical Procedure for Epidural Hematoma Evacuation

    • Location of injury determines surgical approach
    • Frontotemporal craniotomy is the typical surgical procedure for most acute hematoma interventions

    Pre-Operative Preparation

    • Patient's head is secured in a headrest using pins, suction cups, or horseshoe, based on surgeon's preference
    • Patient is anesthetized prior to the procedure

    Scalp Incision and Exposure

    • Scalp incision begins anterior to the tragus and continues superiorly in a question mark shape to the frontal area
    • Scalp is peeled back to expose the skull bone

    Cranial Access

    • Cranial drill is used to puncture the skull at the temporal site
    • Additional burr holes are made in the skull, avoiding major venous structures
    • Anterior burr hole is placed above the frontal sinus

    Dural Access and Hemostasis

    • Formal bone flap is removed to access the dura
    • Bleeding is controlled, and lacerations in the dura are repaired

    Closure and Post-Operative Care

    • Bone flap may or may not be reapplied at the time of closure, depending on degree of cerebral edema
    • A drain may be placed through a separate incision near the surgical site
    • ICP (Intracranial Pressure) monitor may be placed at the end of surgery to monitor postoperative ICP

    Preoperative Period for Anesthetic Management in AHI Patients

    • Patients with Acute Hypertension (AHI) often exhibit partial or complete airway obstruction due to the tongue blocking the posterior pharyngeal space.
    • Additional complications in AHI patients requiring craniotomy include full stomach, decreased intravascular volume, and potential cervical spine injury.
    • Immediate oxygenation and securing of the airway with an endotracheal tube (ETT) may be necessary during the preoperative assessment.
    • Rapid sequence induction with in-line neck manual axial stabilization is appropriate for hemodynamically stable patients.
    • However, intubation may cause an elevation in blood pressure and Intracranial Pressure (ICP).
    • In hemodynamically unstable patients, induction drug dosages are decreased or omitted depending on the level of consciousness.
    • Once the airway is secured, a nondepolarizing muscle relaxant should be administered, followed by mechanical ventilation.
    • The goal of mechanical ventilation is to achieve low normocarbia and a partial arterial pressure carbon dioxide (PaCO2) of approximately 35 mm Hg.
    • In extreme cases of cerebral edema, hypoventilation may be instituted to improve operating conditions.
    • Prolonged and aggressive hyperventilation of PaCO2 should be avoided.

    Anesthesia for Craniotomy Patients with Acute Head Injury (AHI)

    • The primary objective for induction and maintenance of anesthesia is to decrease elevated ICP, optimize cerebral perfusion and oxygenation, and avoid secondary injury from hypoxia and hypotension.

    Induction of Anesthesia

    • Laryngoscopy with ETT placement is best achieved using medications that blunt response to stimulation of laryngoscopy and decrease ICP, while maintaining SBP ≥ 100 mm Hg.
    • Hypnotic agents decrease ICP, CMRO, CBF, and brain metabolism.
    • Propofol and etomidate are good choices for induction of anesthesia in AHI patients, provided blood pressure at the time of induction is adequate or easily supported with fluids and vasopressors.
    • Dex-medetomidine can be used to preserve existing blood pressure in hemodynamically unstable patients.

    Maintenance of Anesthesia

    • Inhalation agents are appropriate for maintaining anesthesia during craniotomy.
    • Isoflurane, desflurane, and sevoflurane all decrease CMRO2 and have a minor effect on metabolic suppression and CBF.
    • However, inhalation agents can cause cerebrovascular dilation and increase CBF, which may further increase ICP, but this effect is dose-dependent and can be minimized with concentrations ≤ 1.0 MAC.

    Ketamine Use

    • Ketamine is relatively contraindicated in AHI patients due to its sympathomimetic action, which increases CBF and ICP.
    • However, some evidence suggests that ketamine may have beneficial effects due to its antagonism of N-methyl-D-aspartate (NMDA) receptors and decrease in glutamate release.

    Cerebral Perfusion Pressure (CPP)

    • CPP is directly related to both mean arterial pressure (MAP) and intracranial pressure (ICP), calculated as CPP = MAP - ICP or CVP.
    • Normal ICP is equal to or less than 10 mm Hg, and normal CPP varies between 80 and 100 mm Hg.
    • If ICP is increased and becomes greater than MAP, CPP is reduced, resulting in reduced CBF.

    Management of Increased ICP

    • Ideal CPP for patients with increased ICP is between 80 and 100 mm Hg.
    • Hyperventilation to a PaCO2 of 25 to 30 mm Hg can be used to manage severely increased ICP.
    • Prolonged hypocarbia is associated with poor neurologic outcome.
    • CBF becomes less sensitive to the effects of hyperventilation within 24 to 48 hours.
    • Periodic hyperventilation is recommended for severe increases in ICP as a temporizing measure.

    Diuretic Therapy

    • Mannitol, an osmotic diuretic, can provide effective ICP reduction intraoperatively.
    • Mannitol administration: 1 g/kg over 10 minutes or slow infusion 0.25 to 1 g/kg over 20 minutes.
    • Mannitol may improve CBF and oxygen delivery by reducing blood viscosity.
    • Hypotension and hypovolemia are possible side effects with mannitol administration.
    • Serum osmolarity should not exceed 320 mOm/L.

    Other Management Techniques

    • Increasing the level of the patient's head from 10 to 30 degrees can lower ICP.
    • Hypertonic saline can decrease cerebral edema.
    • Hypertonic saline 3%: 250 mL can be infused IV over 30 minutes.

    Fluid Requirements and Circulatory Management

    • Hypotension with SBP ≤100 mm Hg is a major contributor to poor neurologic outcome after acute brain injury.
    • Fluid resuscitation and circulatory management should begin immediately.
    • Inotropic and vasopressor medications should be considered to stabilize blood pressure.
    • Administration of dopamine or phenylephrine infusions are recommended to maintain CPP 60 to 110 mm Hg.
    • Fluid resuscitation should be guided by assessing blood pressure, urinary output, and central venous pressure (CVP) readings.
    • Rapid administration of crystalloid and colloid solutions should be monitored to achieve an CPP >60 mm Hg.
    • Isotonic normal saline is the crystalloid of choice to be given via rapid infusion.
    • Monitoring the coagulation status is crucial in patients with an AHI.
    • Blood transfusions may be necessary, and patients with hematocrit below 30% may need a transfusion to promote oxygen delivery to the brain.

    Effects of Temperature on ICP

    • Hypothermia reduces metabolic demand, suppresses excitatory neurotransmitters, diminishes free radical formation, and reduces brain edema.
    • Each degree Celsius decrease in temperature reduces CMRO2 by 7%.
    • Hyperthermia depletes ATP stores, increases calcium influx into cells, and is associated with poor neurologic outcomes.

    Intraoperative Monitoring Modalities

    • Standard American Society of Anesthesiologists (ASA) monitors are essential for intraoperative monitoring.
    • Intraarterial blood pressure measurement, CVP monitoring, and urine output are used.
    • Intraarterial line measurement is necessary for managing CPP and correlating arterial blood gases with ETCO2.
    • CVP catheter placement depends on the risk of VAE and can be inserted in an antecubital vein, subclavian vein, or internal jugular vein.

    Postoperative Complications and Management

    • Delayed awakening: Consider preoperative neuro-logic baseline, residual anesthetic effects, and opioid use.
    • Hypothermia: Use slow active rewarming with forced-air warming device.
    • Seizures: Treat with antiseizure drugs, such as phenytoin, to avoid hypotension.
    • Postoperative cerebral edema: Administer mannitol or furosemide, limit fluids, and monitor CVP readings.
    • Metabolic or electrolyte disturbances: Obtain postoperative electrolytes and correct imbalances.
    • Hematoma: Evaluate with CT scan, obtain coagulation studies, and correct coagulopathy with fresh frozen plasma and platelets.
    • Irregular respiratory pattern and inability to extubate: Consider brainstem ischemia and treat with continuous ventilatory support and serial blood draws.

    Signs Associated with Increased ICP

    • Cushing's Triad: Characterized by widening pulse pressure, bradycardia, and irregular respirations
    • Cardiovascular signs: Widening pulse pressure (increased systolic blood pressure) and bradycardia (slowed heart rate)
    • Neurological signs: Headache, nausea, papilledema (swelling of the optic disc), and altered level of consciousness
    • Ocular signs: Unilateral pupillary dilation, nystagmus (abnormal eye movements), abducens (lateral rectus muscle) palsies, and oculomotor (third cranial nerve) palsies
    • Seizure activity: Increased ICP can lead to seizures

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    This quiz covers the anesthesia objectives and management of acute head injuries, including craniotomy and hypotension. It's essential for anesthesiologists and medical professionals to understand the primary objectives and potential complications.

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