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Pediatric Resident Curriculum for the PICU




                    HEAD INJURY AND
                    INTRACRANIAL HYPERTENSION
          Pediatric Resident Curriculum for the PICU
                                                                 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
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                                                               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
                                                                   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
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                                                       • Assault or nonaccidental trauma
                                                          – Most head injuries in kids < 1 yr are
                                                            from NAT and falls
          Pediatric Resident Curriculum for the PICU
                                                                      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”
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                                                          – Falx cerebri compartmentalizes R and L
                                                            hemispheres
                                                          – Tentorium separates infra- and supratentorial
                                                            regions
          Pediatric Resident Curriculum for the PICU      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
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                                                               compressive, tensile, and shear
                                                               strain in brain tissue
          Pediatric Resident Curriculum for the PICU
                                                       COUP - CONTRECOUP
                                                             INJURY
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                                                          LifeArt: Williams & Wilkins
                                                               http://www.lifeart.com
          Pediatric Resident Curriculum for the PICU   TYPES OF PRIMARY INJURIES

                                                       • Focal injuries      • Diffuse injuries
                                                          – Skull fracture      – Diffuse axonal
                                                          – Parenchymal           injury
                                                            contusion           – Diffuse vascular
                                                          – Parenchymal           injury
                                                            laceration
                                                          – Vascular injury
                                                            resulting in
                                                            hematoma (subdural,
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                                                            extradural, or
                                                            parenchymal)
          Pediatric Resident Curriculum for the PICU
                                                               SKULL FRACTURES
                                                       • Most are uncomplicated
                                                       • Basilar skull fractures
                                                          – Battles sign, “raccoon eyes”
                                                          – CSF rhinorrhea, CSF otorrhea possible
                                                          – Cranial nerve injury possible
                                                       • Depressed skull fractures represent more severe
                                                         injury
                                                          – 1/3 are associated with dural laceration
                                                          – 1/3 are associated with cortical laceration
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                                                          – May require surgical elevation
                                                       • Fracture crossing path of major vascular
                                                         structure increases risk for significant bleeding
                                                          – Middle meningeal artery
                                                          – Large dural sinus
          Pediatric Resident Curriculum for the PICU
                                                                   CONTUSION
                                                       •Usually frontal or
                                                       temporal lobe
                                                       •Small cortical
                                                       vessels and neural
                                                       tissue damaged
                                                       •Damaged vessels
                                                       may thombose,
                                                       leading to ischemia
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                                                                                      WebPath: University of Utah
                                                            http://www-medlib.med.utah.edu/WebPath/webpath.html
          Pediatric Resident Curriculum for the PICU
                                                             INTRACEREBRAL
                                                              HEMORRHAGE
                                                       •Usually frontal or
                                                       temporal lobe
                                                       •Can be bilateral
                                                       (contracoup injury)
                                                       •Can act as mass
                                                       lesions and cause
                                                       intracranial
                                                       hypertension
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          Pediatric Resident Curriculum for the PICU
                                                           EPIDURAL HEMATOMA
                                                       •Usually arterial in origin
                                                       •Between skull and dura,
                                                       limited by suture lines
                                                       •Often from tear in middle
                                                       meningeal artery
                                                       •Initial injury may seem
                                                       minor, followed by “lucid
                                                       interval,” then neurologic
                                                       deterioration
                                                       •May expand rapidly and
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                                                       require emergency
                                                       craniotomy
                                                                                     WebPath: University of Utah
                                                           http://www-medlib.med.utah.edu/WebPath/webpath.html
          Pediatric Resident Curriculum for the PICU
                                                          SUBDURAL HEMATOMA
                                                                               •Usually venous bleeding
                                                                               (bridging veins)
                                                                               •On surface of cortex, beneath
                                                                               dura and outside arachnoid, not
                                                                               limited by suture lines.
                                                                               •Typically requires greater force
                                                                               to produce than epidural
                                                                               hematoma
                                                                               •Usually associated with severe
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                                                                               parenchymal injury

                                                       WebPath: University of Utah
                                                       http://www-medlib.med.utah.edu/WebPath/webpath.html
                                                                       . ...... . ..



          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
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                                                          – 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
                                                         SECONDARY ISCHEMIC BRAIN
                                                                 INJURY
                                                       • Compounds the potential for adverse
                                                         neurologic outcome
                                                       • Caused by:
                                                          – Post injury hypotension
                                                          – Hypoxemia
                                                          – Intracranial hypertension which
                                                            impairs cerebral blood flow
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          Pediatric Resident Curriculum for the PICU
                                                                INTRACRANIAL
                                                                HYPERTENSION
                                                       • Vascular etiologies       • Nonvascular etiologies
                                                          – Vasogenic edema           – Cytotoxic edema
                                                            • BBB impaired,             • Ionic gradients
                                                              protein rich fluid          impaired and cells
                                                              leaks to ECF                swell
                                                         – Hyperemia                  – Obstruction to CSF
                                                            • Occurs days 1 to 3        outflow
                                                              after injury            – Hematoma
                                                         – Obstructed venous          – Osmotic brain edema
                                                           drainage                     • Decreased osmolality
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                                                            • Hydrostatic                 from iatrogenic
                                                              pressure                    hemodilution or
                                                              increased, protein          SIADH
                                                              poor fluid leaks
                                                              into ECF
          Pediatric Resident Curriculum for the PICU
                                                               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
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          Pediatric Resident Curriculum for the PICU
                                                       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
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                                                           hypertension
                                                         – Avoid measures that decrease cerebral
                                                           perfusion
          Pediatric Resident Curriculum for the PICU
                                                                 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
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                                                         –   Rapid neurologic deterioration
                                                         –   If needed for other injuries
          Pediatric Resident Curriculum for the PICU
                                                         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
                                                         – C-spine injuries in as many as 10% of head
                                                           injury patients
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                                                         – In-line axial stabilization by an assistant
                                                           recommended
          Pediatric Resident Curriculum for the PICU
                                                       DRUGS FOR RAPID SEQUENCE
                                                              INTUBATION
                                                       • Analgesia/sedation • Neuromuscular blockade
                                                          – Fentanyl, etomidate – Succinyl choline
                                                             • little effect on BP    • short acting
                                                          – Thiopental                • muscle
                                                             • decreases ICP but        fasciculations can
                                                               can drop BP              increase ICP
                                                       • Anxiolysis                   • use with
                                                          – Midazolam                   defasciculating
                                                                                        dose of
                                                             • little effect on BP      nondepolarizing
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                                                       • Lidocaine IV              – Non depolarizing
                                                             • blunts                 • vecuronium
                                                               sympathetic
                                                               response to            • longer acting and
                                                               intubation               no increase in ICP
          Pediatric Resident Curriculum for the PICU   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)
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                                                          – Hyperventilate
                                                          – Give mannitol
          Pediatric Resident Curriculum for the PICU
                                                       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
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                                                          – Cannot be recalibrated
                                                          – Exhibits drift in values measured over
                                                            time
          Pediatric Resident Curriculum for the PICU
                                                       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
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          Pediatric Resident Curriculum for the PICU   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
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                                                             result in a falsely low calculated CPP
          Pediatric Resident Curriculum for the PICU   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
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          Pediatric Resident Curriculum for the PICU
                                                       FACTORS AFFECTING INTRACRANIAL
                                                                 PRESSURE
                                                       • Increases ICP          • Decreases ICP
                                                          – hypercarbia           – hyperoxia
                                                          – hypoxia (pO2 <        – hypothermia
                                                            50)
                                                                                  – barbiturates
                                                          – seizures or
                                                            shivering             – hypocapnia
                                                          – hyperthermia             • via cerebral
                                                          – arousal                    vasoconstrictio
                                                                                       n
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                                                             • pain, anxiety
                                                          – venous                   • lowers CPP and
                                                            congestion                 is undesirable
                                                             • fluid overload
                                                             • intrathoracic
          Pediatric Resident Curriculum for the PICU
                                                            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
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                                                            prevent
                                                            impending
                                                            herniation but
                                                            will worsen
                                                            secondary
                                                            ischemic injury
          Pediatric Resident Curriculum for the PICU
                                                        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
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                                                          – Watch for and treat hypotension
                                                       • Seizure prophylaxis
                                                          – Phenytoin or phosphenytoin
          Pediatric Resident Curriculum for the PICU   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
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                                                            by several mm Hg
                                                          – Maintain temp < 37.5 o C
                                                            • Scheduled acetaminophen, body
                                                              exposure, cooling blanket
          Pediatric Resident Curriculum for the PICU
                                                         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
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                                                            •   Hypotension
                                                         – Follow serum osmolality and Na
                                                            • Hold mannitol if serum osm > 320
                                                              mOsm/l
          Pediatric Resident Curriculum for the PICU
                                                        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
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                                                           cerebral edema has obliterated or
                                                           significantly compressed ventricles
          Pediatric Resident Curriculum for the PICU
                                                        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
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                                                         –   hypothermia
          Pediatric Resident Curriculum for the PICU
                                                               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
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                                                              pupils while large doses may cause mid
                                                              position to 5 mm nonreacting pupils
                                                            • Watch for hypotension
          Pediatric Resident Curriculum for the PICU
                                                              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
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                                                         – 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
                                                              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
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                                                            • Hypokalemia
                                                            • Increased risk of infection
          Pediatric Resident Curriculum for the PICU
                                                         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
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                                                            • 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
                                                         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
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                                                         – 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
                                                         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
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                                                         – Follow electrolytes closely
                                                            • Avoid hyponatremia
                                                            • Mannitol can cause electrolyte
                                                              abnormalities
                                                            • Watch for SIADH, diabetes insipidus,
          Pediatric Resident Curriculum for the PICU
                                                         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
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                                                              healthy
                                                         – Avoid hyperglycemia
                                                            • Associated with poor neurologic outcome
                                                            • Watch serum glucose closely if dextrose
                                                              containing fluids used
          Pediatric Resident Curriculum for the PICU
                                                         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
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                                                           active bleeding or if surgical intervention
                                                           anticipated
                                                         – Maintain normal hematocrit to optimize
                                                           oxygen delivery
          Pediatric Resident Curriculum for the PICU
                                                         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 dextrose-
                                                              containing fluids
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                                                              Continuous vasopressin infusion or DDAVP
                                                              (subQ or intranasal) q 12 to 24 hrs
          Pediatric Resident Curriculum for the PICU
                                                         MANAGEMENT OF OTHER
                                                              SYSTEMS
                                                       • Endocrine
                                                         – CEREBRAL SALT-WASTING
                                                            • ANP-like substance released from brain,
                                                              inducing natriuresis and diuresis

                                                         – SIADH
                                                            • Elevated level of ADH inappropriate for
                                                              prevailing osmotic or volume stimuli
                                                            • Hyponatremia, hypo-osmolality, urine osm
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                                                              > plasma osm, high urine Na
                                                            • Treatment is water restriction
          Pediatric Resident Curriculum for the PICU
                                                                     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
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                                                         – Avoid factors that increase ICP
                                                         – Treat intracranial hypertension

				
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