TĂNG ÁP LỰC NỘI SỌ Ơ NGƯỜI

Increased Intracranial Pressure Bs Phùng Nguyễn Thế Nguyên BM Nhi- ĐHYD Content Physiology Difinition Clinical symtoms Causes Treatments Monitor Objectives Define ICP and related terminology Identify symtoms and signs with elevated ICP Identify causes of elevated ICP Aply treatment inceased ICP Physiology  Intracranium: protected by the skull, fixed internal volume  Intracranial contents include:  Brain parenchyma — 80%  Cerebrospinal fluid (CSF) — 10%  Blood — 10%  In adult: total volume of 1450 mL: 1300 mL of brain, 65 mL of CSF, and 110 mL of blood Physiology  CBF = Carotid AP – V Jugular P + Cerebral VR  PaO2 < 50 mmHg: vasodilation  PaCO2 > 35 mmHg: vasodilation  PaCO2 < 25: Vasocontriction  Response to PaCO2: quickly Physiology  Autoregulation - (CBF):  metabolic activity, primarily through changes in CVR, increase metabolic activity (seizures, fever) result in increased CBF  mean arterial pressures of 60 to 150 mmHg  the brain is able to maintain a normal cerebral blood flow (CBF) with a CPP ranging from 50 to 150 mm Hg  CPP < 50 mm Hg, the brain may not be able to compensate adequately Physiology  Cerebral perfusion pressure (CPP):  CPP = MAP – ICP  Normal CPP 50 to 60 mmHg If MAP cannot increase:  Increased ICP = Decreased CPP  Decreased CPP = Tissue ischemia  Tissue ischemia = Edema Physiology  Cerebral edema:  Cytotoxic edema:  direct cell injury (traumatic brain injury, hypoxic-ischemic injury) irreversibly injured, poor outcome although treatment  reversible cytotoxic edema with water intoxication  Vasogenic edema: increased permeability of capillary endothelial cells (tumors, intracranial hematomas, infarcts, abscesses, and central nervous system infections)  Interstitial edema: Increased CSF hydrostatic pressure Difinition  Normal ICP:  Adult: 10 - 15 mmHg  young children: to mm Hg  term infants: 1.5 to mm Hg  Increase ICP: > 20 mmHg (upto date) 10 Hypothermia  a prospective, blinded, randomized multicenter trial of 225 children with severe brain injury caused by blunt trauma found no benefit and possibly worse outcomes < 32 to 33ºC  Based on these findings, controlled hypothermia, as performed in this protocol, is not recommended 61 Steroids  Steroids may have a role in reducing vasogenic edema and other inflammatory processes  helpful in the management of vasogenic edema associated with mass lesions (eg, tumors and abscesses)  However, they are not recommended for the treatment of increased ICP [40]  Studies in children have demonstrated that the use of corticosteroids does not significantly reduce ICP, and there is no difference in longterm outcomes in children treated with corticosteroids [41]  not useful in the management of elevated ICP from infarction, hemorrhage, or head trauma 62 Steroids  Dexamethasone: 0.25 to 0.5 mg/kg/6 hours 63 Etomidate  A recent study evaluated the use of etomidate to reduce ICP in children with severe TBI  Eight children were given a dose of 0.3 mg/kg of etomidate  All patients had a significant reduction in ICP and improvement in CPP [42]  Further investigation is needed to confirm these results,  but etomidate may be another reasonable treatment option Because it has a short onset of action and short duration of action, it may be useful for acute increases in ICP 64 65 66 CONTRAINDICATED THERAPIES  Nitroglycerin and nitroprusside  Ketamine: increase CBF  Hypotonic solutions (eg, D5W), that deliver too much free water and can exacerbate cerebral edema  hyperglycemia and hypoglycemia 67 Monitoring  There are main types of devices for monitoring ICP4  Intraventricular Catheters  Fiber optic Monitors  Subarachnoid Bolts  Epidural Monitors 68 Monitoring 69 Intraventricular Catheters4  Most widely used devices – Most Accurate  A catheter is actually placed inside one of the ventricles  Allows treatment and monitoring simultaneously  Can be used to take out excess CSF, thereby decreasing ICP 70 Fiber optic Monitors4  Relatively new technology  A fiber-optic probe is inserted  Into the Brain  Ventricles  Subdural space  The probe contains a transducer on the tip that measures pressure 71 72 73 Subarachnoid Bolts4  These consist of an actual metal “bolt” that is inserted into the skull so that the tip is resting in the subarachnoid space  Easy to install (hey… it’s what they said!)  Limited accuracy 74 Epidural Monitors4  Recording devices that are placed into the epidural space  This is a potential space that is located between the inner surface of the skull and the dura matter 75 ... 110 mL of blood Physiology  CBF = Carotid AP – V Jugular P + Cerebral VR  PaO2 < 50 mmHg: vasodilation  PaCO2 > 35 mmHg: vasodilation  PaCO2 < 25: Vasocontriction  Response to PaCO2: quickly... syndrome, macrocephaly, hormonal abnormalities)  Lethargy  Personality change 14 Signs  Papilledema: it takes several days to become apparent 15 Signs  macrocephaly, split sutures or bulging fontanel... obstruction and reabsorption  Impaired venous outflow 27 Treatment  Goals of therapy Maintain ICP at less than 20 to 25 mm Hg Maintain CPP at greater than 60 mm Hg by maintaining adequate MAP Avoid factors