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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
                                                           tissue deformation at the moment of
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                                                           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