head-trauma1 - Pediatric Resident Curriculum for the PICU...

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Unformatted text preview: Pediatric Resident Curriculum for the PICU UTHSCSA HEAD INJURY AND INTRACRANIAL HYPERTENSIO Pediatric Resident Curriculum for the PICU UTHSCSA HEAD INJURY • • • • Major cause of morbidity and mortality in children Leading cause of death in children > 1 yr is trauma Head injuries responsible for most trauma deaths Adverse outcomes result from – Primary injury • Result of mechanical forces producing tissue deformation at the moment of injury – Secondary ischemic injury • Associated with post injury hypotension, hypoxemia, and intracranial hypertension Pediatric Resident Curriculum for the PICU UTHSCSA ETIOLOGIES • Motor vehicle accidents – Responsible for most severe head injuries • Falls – Usually in children < 4 yrs and usually mild • Recreational activities – Half of these are bicycle accidents • Assault or nonaccidental trauma – Most head injuries in kids < 1 yr are from NAT and falls Pediatric Resident Curriculum for the PICU UTHSCSA ANATOMY • Uniquely susceptible to injury • Brain – Inelastic and noncompressible – Has no internal support • Cranium – Rigid and unyielding after sutures fused – Bony buttresses at anterior poles and temporal poles • Membranous “slings” – Falx cerebri compartmentalizes R and L hemispheres – Tentorium separates infra­ and supratentorial regions Pediatric Resident Curriculum for the PICU UTHSCSA MECHANISM OF BRAIN INJURY • Brain is thrown against bony irregularities or membranous slings or compressed against these surfaces by… – Contact injury • Head strikes or is struck by an object – Acceleration/deceleration injury • Violent head motion causes compressive, tensile, and shear strain in brain tissue Pediatric Resident Curriculum for the PICU UTHSCSA COUP ­ CONTRECOUP INJURY LifeArt: Williams & Wilkins http://www.lifeart.com Pediatric Resident Curriculum for the PICU UTHSCSA TYPES OF PRIMARY INJURIES • Focal injuries • Diffuse injuries – Skull fracture – Diffuse axonal injury – Parenchymal contusion – Diffuse vascular – Parenchymal laceration injury – Vascular injury resulting in hematoma (subdural, extradural, or parenchymal) Pediatric Resident Curriculum for the PICU UTHSCSA SKULL FRACTURES • Most are uncomplicated • Basilar skull fractures – – – Battles sign, “raccoon eyes” CSF rhinorrhea, CSF otorrhea possible Cranial nerve injury possible – – – 1/3 are associated with dural laceration 1/3 are associated with cortical laceration May require surgical elevation • Depressed skull fractures represent more severe injury • Fracture crossing path of major vascular structure increases risk for significant bleeding – Middle meningeal artery – Large dural sinus Pediatric Resident Curriculum for the PICU UTHSCSA CONTUSION •Usually frontal or Usually temporal lobe temporal •Small cortical Small vessels and neural tissue damaged tissue •Damaged vessels Damaged may thombose, leading to ischemia leading WebPath: University of Utah http://www-medlib.med.utah.edu/WebPath/webpath.html Pediatric Resident Curriculum for the PICU UTHSCSA INTRACEREBRAL HEMORRHAGE •Usually frontal or Usually temporal lobe temporal •Can be bilateral Can (contracoup injury) (contracoup •Can act as mass Can lesions and cause intracranial hypertension hypertension Pediatric Resident Curriculum for the PICU UTHSCSA EPIDURAL HEMATOMA EPIDURAL HEMATOMA •Usually arterial in origin •Between skull and dura, Between limited by suture lines limited •Often from tear in middle Often meningeal artery meningeal •Initial injury may seem Initial minor, followed by “lucid interval,” then neurologic deterioration deterioration •May expand rapidly and May require emergency craniotomy WebPath: University of Utah http://www-medlib.med.utah.edu/WebPath/webpath.html Pediatric Resident Curriculum for the PICU UTHSCSA SUBDURAL HEMATOMA •Usually venous bleeding Usually (bridging veins) (bridging •On surface of cortex, beneath On dura and outside arachnoid, not limited by suture lines. limited •Typically requires greater force Typically to produce than epidural hematoma hematoma •Usually associated with severe Usually parenchymal injury parenchymal WebPath: University of Utah http://www-medlib.med.utah.edu/WebPath/webpath.html UTHSCSA Pediatric Resident Curriculum for the PICU . ...... . .. DIFFUSE BRAIN INJURY • Diffuse axonal injury – Usually from rapid acceleration/deceleration – Shear forces disrupt small axonal pathways • After disruption, axons degenerate, fragment, then disappear • The neurons then undergo Wallerian degeneration – Spectrum from mild to severe • Diffuse vascular injury – Microvasculature more resistant to shear than axons – Results in multiple small hemorrhages throughout brain – Usually seen in fatal head injuries Pediatric Resident Curriculum for the PICU UTHSCSA SECONDARY ISCHEMIC BRAIN INJURY • Compounds the potential for adverse neurologic outcome • Caused by: – Post injury hypotension – Hypoxemia – Intracranial hypertension which impairs cerebral blood flow Pediatric Resident Curriculum for the PICU UTHSCSA INTRACRANIAL HYPERTENSION • Vascular etiologies – Vasogenic edema • Nonvascular etiologies – Cytotoxic edema • BBB impaired, protein rich fluid leaks to ECF – Hyperemia • Occurs days 1 to 3 after injury – Obstructed venous drainage • Hydrostatic pressure increased, protein poor fluid leaks into ECF • Ionic gradients impaired and cells swell – Obstruction to CSF outflow – Hematoma – Osmotic brain edema • Decreased osmolality from iatrogenic hemodilution or SIADH Pediatric Resident Curriculum for the PICU UTHSCSA INTRACRANIAL HYPERTENSION • Normal intracranial pressure: – Adults: < 10 mm Hg – Infants/children: somewhat lower, depending on age • Elevated ICP impairs cerebral perfusion • Risk for herniation with ICP > 40 mm Hg • Herniation can occur at lower ICP’s when mass lesion is present Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF HEAD INJURY • Goals of resuscitation and treatment is to minimize secondary ischemic brain injury by promoting and preserving cerebral perfusion Prevent or treat post injury hypotension Prevent or treat hypoxemia and reduce oxygen demand of the brain – Prevent or treat intracranial hypertension – Avoid measures that decrease cerebral perfusion – – Pediatric Resident Curriculum for the PICU UTHSCSA RESUSCITATION • • A, B,C’s Major early risk is hypotension – Adequate fluid resuscitation to restore normal BP does NOT worsen neurologic outcome – Avoid hypotonic fluids • Emergent airway control for – – – – GCS 8 or less GSC 10 or less with abnormal head CT Rapid neurologic deterioration If needed for other injuries Pediatric Resident Curriculum for the PICU UTHSCSA INTUBATION OF PATIENT WITH HEAD INJURY • • Preserve cerebral oxygenation Maintain cerebral perfusion – – – – Adequate analgesia and anxiolysis Avoid meds that increase ICP Avoid meds that cause hypotension Avoid Trendelenburg position • Avoid aggravating C spine injury – C­spine injuries in as many as 10% of head injury patients – In­line axial stabilization by an assistant recommended Pediatric Resident Curriculum for the PICU UTHSCSA DRUGS FOR RAPID SEQUENCE INTUBATION • Analgesia/sedation • Neuromuscular blockade – Fentanyl, etomidate – Succinyl choline • little effect on BP • short acting – Thiopental • muscle fasciculations can increase ICP • decreases ICP but can drop BP • use with defasciculating dose of nondepolarizing • Anxiolysis – Non depolarizing – Midazolam • vecuronium • little effect on BP • longer acting and no • Lidocaine IV increase in ICP • blunts sympathetic response to intubation Pediatric Resident Curriculum for the PICU UTHSCSA RULE OUT & PREVENT NEUROSURGICAL EMERGENCIES • Head CT as soon as possible – Initial CT may be normal in severe head injury – Repeat CT in 12 to 24 hours • Moderate hyperventilation advisable during transport and initial evaluation • If signs of impending herniation develop (lateralizing signs, pupil asymmetry) – Hyperventilate – Give mannitol Pediatric Resident Curriculum for the PICU UTHSCSA MONITORING OF INTRACRANIAL PRESSURE • Ventriculostomy catheter – Catheter tip in frontal horn of lateral ventricle – Can drain CSF – Can be recalibrated as necessary • Transducer tipped catheter – Intraparenchymal or subdural – Cannot drain CSF – Cannot be recalibrated – Exhibits drift in values measured over time Pediatric Resident Curriculum for the PICU UTHSCSA MONITORING OF INTRACRANIAL PRESSURE • Indications – – – GCS < 8 after resuscitation Abnormal head CT Rapid neurologic deterioration • ICP monitoring is continued for as long as treatment of intracranial hypertension is required Pediatric Resident Curriculum for the PICU UTHSCSA CEREBRAL PERFUSION PRESSURE • Can be determined from ICP and mean arterial pressure: CPP = MAP ­ ICP • Calculated CPP does not reflect perfusion of entire brain – CPP further decreased in areas of injury – Factors that cause cerebral vasoconstriction without lowering MAP result in a falsely low calculated CPP Pediatric Resident Curriculum for the PICU UTHSCSA CEREBRAL PERFUSION PRESSURE • Goal of therapy CPP > 60 mm Hg if ICP < 22 mm Hg or CPP > 70 mm Hg if ICP > 22 mm Hg – Lowering ICP while maintaining MAP will increase CPP – Increasing MAP will increase CPP Pediatric Resident Curriculum for the PICU UTHSCSA FACTORS AFFECTING INTRACRANIAL PRESSURE • Increases ICP • Decreases ICP – hypercarbia – hyperoxia – hypoxia (pO2 < 50) – hypothermia – seizures or shivering – barbiturates – hyperthermia – hypocapnia – arousal • via cerebral • pain, anxiety vasoconstriction – venous congestion • lowers CPP and is • fluid overload undesirable • intrathoracic pressure Pediatric Resident Curriculum for the PICU UTHSCSA EFFECT OF pCO2 and pO2 ON CBF AND CPP • Hypoxia increases CBF by vasodilation • Hypercapnia increases CBF • Hyperventilation and resulting hypocapnia decrease CBF – Hyperventilation is useful to prevent impending herniation but will worsen secondary ischemic injury Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF INCREASED ICP • Head position – Head elevated 30 degrees and midline • Sedation and pain control – Analgesic + anxiolytic • Fentanyl, morphine, or propofol plus a benzodiazepine • Continuous infusions or scheduled doses to maintain sedation – Watch for and treat hypotension • Seizure prophylaxis – Phenytoin or phosphenytoin Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF INCREASED ICP • Neuromuscular blockade – Facilitates mechanical ventilation and control of pCO2 – Prevents shivering – Use if movement increases ICP • Temperature control – A rise in temp of 1o C increases cerebral metabolic rate by 10%, increasing ICP by several mm Hg – Maintain temp < 37.5 o C • Scheduled acetaminophen, body exposure, cooling blanket Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF INCREASED ICP • Osmotherapy with mannitol – Decreases extracellular fluid in brain – Intermittent doses for ICP spikes or scheduled if elevated ICP is persistent – Adverse effects: • • • • Hypernatremia, hypokalemia Hyperosmolality Hemodilution and drop in hematocrit Hypotension – Follow serum osmolality and Na • Hold mannitol if serum osm > 320 mOsm/l Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF INCREASED ICP • Drainage of CSF – Possible if ventricular catheter is in place – CSF drainage pressure usually set at 20 cm H2O – CSF drains when ICP exceeds drainage pressure – Ventricular catheters cannot be placed if cerebral edema has obliterated or significantly compressed ventricles Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF INCREASED ICP • Second tier therapies for intracranial hypertension refractory to sedation, muscle relaxation, osmotherapy, and moderate hypothermia: – – – – barbiturate “coma” induced hypertension decompressive craniotomy hypothermia Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF INCREASED ICP • Barbiturate “coma” – ICP control is the principal endpoint – EEG burst suppression is a useful guide to optimal barbiturate dosage • Pentobarbital 10mg/kg followed by infusion at 1 mg/kg/hr, titrated to effect • May give additional boluses during infusion for acute spikes in ICP • Moderate doses cause sluggishly reactive pupils while large doses may cause mid position to 5 mm nonreacting pupils • Watch for hypotension Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF INCREASED ICP • Induced hypertension – Inotropes to increase MAP, even beyond normal for age, to achieve an optimal CPP • Dopamine • Norepineprine – Rise in ICP in tandem with a rise in MAP implies total loss of autoregulation and is a poor prognostic sign • Decompressive craniotomy – Large portion of cranium removed to allow room for brain to swell and minimize ischemia – Dura must be opened as well Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF INCREASED ICP • Hypothermia – Core body temp of 32o to 33o C – Reduced cerebral metabolic activity, reducing ICP – Also has cytoprotective effects – Adverse effects • Arrythmias • Coagulopathies • Hypokalemia • Increased risk of infection Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF OTHER SYSTEMS • Respiratory – Maintain normocapnia • Hyperventilation only appropriate during early diagnosis and management or if herniation is impending – Maintain oxygenation • pO2 > 100 is optimal – PEEP to maintain alveolar recruitment • ARDS, neurogenic pulmonary edema frequent complications • Hypoxemia has more deleterious effects on brain than modest venous congestion caused by PEEP • PEEP of 5 to 10 cm H2O not shown to have detrimental effect on neurologic outcome Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF OTHER SYSTEMS • Cardiovascular – Maintain normal blood pressure • Hypotension significantly reduces CPP • Inotropes if necessary to maintain normal BP – Induced hypertension if necessary • Gastrointestinal – Stress gastritis prophylaxis with H2 blocker – Jejunal feeds to maintain healthy intestinal mucosa and prevent bacterial translocation from gut Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF OTHER SYSTEMS • Fluids, Electrolytes, Nutrition – Goal is NORMOVOLEMIA • Total fluid intake should be @ 100% maintenance • Bolus as necessary to achieve normal CVP – Avoid hypotonic fluids • Lactated Ringer’s and 0.9% saline w/ 20 mEq KCl/l are good choices for maintenance fluids – Follow electrolytes closely • Avoid hyponatremia • Mannitol can cause electrolyte abnormalities • Watch for SIADH, diabetes insipidus, cerebral salt wasting Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF OTHER SYSTEMS • Fluids, electrolytes, nutrition – Provide calories to meet metabolic demands of patient • Increased metabolic demands during acute phase of injury • Heavily sedated, relaxed, cooled patient has decreased metabolic demands • Enteral feedings via nasojejunal catheter preferable to TPN if gut deemed to be healthy – Avoid hyperglycemia • Associated with poor neurologic outcome • Watch serum glucose closely if dextrose containing fluids used Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF OTHER SYSTEMS • Renal – Place foley for strict I’s and O’s • Hematologic – Coagulopathy common with head injuries • Brain derived thromboplastin activator substances released – Follow PT/PTT or DIC screens – Blood component replacement if evidence of active bleeding or if surgical intervention anticipated – Maintain normal hematocrit to optimize oxygen delivery Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF OTHER SYSTEMS • Endocrine – DIABETES INSIPIDUS • Complete or partial failure of ADH secretion from shearing of pituitary stalk • Polyuria, hypernatremia, urine osm < plasma osm • Treatment: Run maintenance fluids @ 100% Replace urine output cc for cc with dextrose­containing fluids Continuous vasopressin infusion or DDAVP (subQ or intranasal) q 12 to 24 hrs Pediatric Resident Curriculum for the PICU UTHSCSA MANAGEMENT OF OTHER SYSTEMS • Endocrine – CEREBRAL SALT­WASTING • ANP­like substance released from brain, inducing natriuresis and diuresis – SIADH • Elevated level of ADH inappropriate for prevailing osmotic or volume stimuli • Hyponatremia, hypo­osmolality, urine osm > plasma osm, high urine Na • Treatment is water restriction Pediatric Resident Curriculum for the PICU UTHSCSA SUMMARY • Identify and treat primary brain injury – Rule out neurosurgical emergency • Minimize secondary ischemic brain injury by promoting cerebral perfusion – – – – – Maintain normovolemia and adequate BP Maintain normal electrolytes and euglycemia Maintain normocapnia and adequate oxygenation Avoid factors that increase ICP Treat intracranial hypertension ...
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This note was uploaded on 12/24/2011 for the course STEP 1 taught by Professor Dr.aslam during the Fall '11 term at Montgomery College.

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