Presentation on theme: "Sophia R. Smith, MD WRAMC November 2, 2005"— Presentation transcript:
1Sophia R. Smith, MD WRAMC November 2, 2005 ICP & Head TraumaSophia R. Smith, MDWRAMCNovember 2, 2005
2IntroductionHead injuries are one of the most common causes of disability and death in children.The Centers for Disease Control and Prevention (CDC) estimates that more than 10,000 children become disabled from a brain injury each year.Head injuries can be defined as mild as a bump to severe in nature.
3Prevalence of Pediatric Trauma Trauma is the leading cause of death in infants and childrenTrauma is the cause of 50% of deaths in people between 5 and 34 years of ageMotor vehicle related accidents account for 50% of pediatric trauma cases$16 billion is spent annually caring for injuries to children less than 16 years of age
4Traumatic Brain Injury Primary Brain InjuryResults from what has occurred to the brain at the time of the injurySecondary Brain InjuryPhysiologic and biochemical events which follow the primary injury
7Factors that Effect Secondary Brain Injuries Blood PressureOxygenationTemperatureControl of Blood GlucoseFluid Volume StatusIncreased Intracranial Pressure
8SOME of the SECONDARY EVENTS IN TRAUMATIC BRAIN INJURY diffuse axonalinjuryinflammationBBBdisruptionapoptosisnecrosisedemaformationBrain traumaischemiaenergy failurecytokinesEicosanoidsendocannabinoidsCalciumpolyaminesAcetylCholineROSShohami, 2000Green – pathophysiological processes; Yellow – various mediators
9Anatomy of the craniumThere are various brain contents that are localized within a rigid structure.CraniumThe cranial vault contents include:The brainThe cerebral spinal fluidThe cerebral blood
10Cerebral Spinal Fluid CSF 150 cc in adults at all times Children slightly lessProduced by choroid plexus – 20 cc/hrCSF is absorbed into venous system at the subarachnoid villi
11Cerebral blood and brain Sum of blood in capillaries, veins, and arteriesBrain80% of the total intracranial volumeAll of these contents are a balanced pressure referred to as intracranial pressure (ICP)
12Monro-Kellie Doctrine The ICP within the skull is directly related to the volume of the contents.Defined as the Monro-Kellie DoctrineThis doctrine states that any increase in volume of the contents within the brain must be met with a decrease in the other cranial contents.
15Cerebral Blood FlowCBF is directly linked to the metabolic requirements of the brain.As the brain metabolic activity increases, CBF increasesVasodilatation of cerebral vesselsIncrease in cerebral blood volumeConsequent increase in ICP
16Cerebral blood flow CBF maintained when MAP range is 50mmHg to 150mmHg Cerebral auto regulationAs BP increase baroreceptors sense event and cerebral arteries vasoconstrict CBF maintained with a CBV decreaseAs BP decrease cerebral arteries dilate to increase flow CBV increase
17Auto regulation This process is lost in pathological states Esp. Head traumaCBF decreases linearly to MAP below rangeResults is ischemia (strokes) to brain regionsCBF increases linearly to MAP above auto regulation rangeHTN encephalopathy as CBV and ICP increase
19Mediators of CBFLocal and global mediators of CBF and metabolism are important.Hypoxia and pH are most importantAs local paO2 decreases, CBF increasesCBF is affected by pH (and its surrogate pCO2)
20Blood: Cerebral Blood Flow The brain has the ability to control its blood supply to match its metabolic requirementsChemical or metabolic byproducts of cerebral metabolism can alter blood vessel caliber and behavior
21Studies of hyperventilation & ICP This relationship has been well studied as a therapeutic option in particular intentional hyperventilation to lower cerebral blood flow and thus intracranial pressure.No longer a practiceModest hyperventilation
22On callSo, you are in the ER on your first night of call and the next thing you know you get your very first trauma patient.How do you evaluate?
25Glascow Coma ScaleEye Opening Spontaneous 4 To Voice 3 To Pain 2 None 1 Best Verbal Oriented 5 Confused 4 Inappropriate Words 3 Incomprehensible Sounds 2 None 1 Best Motor Obeys Commands 6 Localizes Pain 5 Withdraws to Pain 4 Flexion to Pain 3 Extension to Pain 2 None 1
27Severe TBI Indications for Intubation GCS< 8 Fall in GCS of 3 Unequal pupilsInadequate respiratory effort or significant lung/chest injuryLoss of gagapnea
28TreatmentIntubation.Pretreatment with lidocaine 1 mg/kg IV may prevent rise in intracranial pressure (ICP).
29Treatment Hyperventilation to maintain PO2 >90 torrs, PCO2 30 to 32 torrs.Hyperventilation may actually increase ischemia in at risk brain tissue if PCO2 <25 torr by causing excessive vasoconstriction and has fallen out of favor. Prophylactic hyperventilation for those without increased ICP is contraindicated and worsens outcomes.PEEP relatively contraindicated because reduces cerebral blood flow.
30Maintain normal cardiac output. If hypotensive from other cause such as multi-trauma, treat shock as usual.Normal saline is preferred over LR since LR is slightly hypotonic.Hypertonic saline (3% or 7.5%) can be used. Especially if you see ICP changes.
31Maintain normal cardiac output. If markedly hypertensive, consider labetalol or nitroprusside.Avoid lowering the blood pressure unless diastolic blood pressure is >120 mm Hg.
32Diuresis Mannitol 1 g/kg IV over 20 minutes induces osmotic diuresis. Avoid if hypotensive or have CHF/renal failure.Some suggest furosemide (Lasix and others).Avoid if hypotensive.
33ICP Precautions Elevate head of bed 30 degrees. Seizure prophylaxis: Phenytoin will reduce seizures in the first week after injury but does not change the overall outcome.Steroids are ineffective in controlling ICP in the trauma setting.
35Manipulation of CPP CPP = MAP - ICP Maintain adequate intravascular volumeCVPIncrease MAPUtilize alpha agonist--dopamine, phenylephrine, norepinephrineWhat is appropriate goal for children?
36CPP for children Aim for a CPP of >60 mmHg by maintaining an adequate MAP and control of ICPMAP – ICP = CPPMinimizing the morbidity of TBI in children
37Additional therapiesPrevent hyperglycemia: exacerbates ischemic cerebral damageAttention to electrolyte status. These patients are prone to electrolyte abnormalities due to osmotic diuresis, cerebral salt losing states, SIADH and diabetes insipidus
38Manipulation of ICP Blood Decrease cerebral metabolic demand sedation, analgesia, barbituratesavoid hyperthermiaavoid seizuresHyperventilationdecreases blood flow to brainonly acutely for impending herniationMannitol
39Manipulation of ICP Brain Mannitol Hypertonic saline dehydrate the brain, not the patient!monitor osmolalityHypertonic salineDecompressive craniectomy
40ICP MonitoringICU patients who have sustained head trauma, brain hemorrhage, brain surgery, or conditions in which the brain may swell might require intracranial pressure monitoring.The purpose of ICP monitoring is to continuously measure the pressure surrounding the brain.
43Manipulation of ICP CSF External drainage therapeutic as well as diagnostictechnical issuesinfectious issues
44What to do with the information... Goal: adequate oxygen delivery to maintain the metabolic needs of the brain.Intracranial pressure <20Cerebral perfusion pressure >50-70 mm Hg CPP=MAP-ICP
45Indications for ICP monitoring Glasgow coma scale <8Clinical or radiographic evidence of increased ICPPost-surgical removal of intracranial hematomaLess severe brain injury in the setting which requires deep sedation or anesthesia
47Near-infrared Spectroscopy Uses absorption characteristics of oxy Hgb, deoxy Hgb, and [o] cyt aa3Uses the ability to penetrate the superficial brainTherefore the state of oxygenation can be determined.Good assessment of cerebral oxygenation
48Transcranial Doppler US TCD is a noninvasive technique used to determine cerebral blood velocity in large intracranial arteries.Assessment ofBrain deathReperfusion injuryIdentify regions S/P TBI that are adversely effected
49Cerebral Microdialysis Measuring the partial pressure of oxygen of brain parenchyma and metabolites using microdialysisElectrode in vulnerable brain region measures O2 concentrationMeasures also local brain metabolism