Increased Intracranial Pressure And Cerebral Edema

Intracranial hypertension is operationally defined as sustained ICP > 20 mmHg. A patient with suspected elevated ICP and a deteriorating level of consciousness requires invasive ICP monitoring (44). IVCs are considered the gold standard ICP monitor. This form of external ventricular drainage is also useful in treatment of elevated ICP because IVCs allow cerebro-spinal fluid drainage. Recommendations to use antibiotic prophylaxis and to periodically exchange IVCs are largely the result of routine practice, which is institution related rather than data driven. Optimal head position can be adjusted according to ICP values. Evidence in the literature is insufficient to support the prophylactic use of mannitol or hypernatremia; hyponatremia should, however, be avoided to prevent the development or worsening of cerebral edema. In the presence of elevated ICP or herniation syndromes, osmotherapy, using either mannitol with a serum osmolality goal of 310 to 315 mOsm/Lt or hypertonic saline with a serum sodium target of 145 to 155 mEq/Lt, is recommended (45). Controlled hyperventilation with a PaCO2 goal of 27 to 30 mmHg lowers ICP faster than osmotherapy, because it causes cerebral vasoconstriction and an almost immediate reduction in cerebral blood volume, although peak ICP reduction might take up to 30 minutes. The ICP reducing effects of hyperventilation cease when the cerebrospinal fluid pH reaches equilibrium. In practice, however, this might take several hours. Gradual normalization of serum PCO2 over 24 to 48 hour is recommended, so as to avoid rebound intracranial hypertension.

Corticosteroid use in the management of perihematoma brain edema has failed to demonstrate a positive impact on the outcome of ICH patients (46,47). The limitations of these studies, however, are multiple. Current knowledge of outcome predictors following ICH (48) (initial GCS, admission pulse pressure, hematoma volume, presence of IVH, and hydrocepha-lus) were not considered and, therefore, not controlled for in any of these studies, as most of them were performed in the early 1980s, and some even before CT scan technology was available. Contemporary studies on the use of corticosteroids or other immunosuppressant therapy with potential to prevent or treat perihematoma brain edema will certainly improve our knowledge in this area.

Neuromuscular paralysis in combination with adequate sedation can reduce elevated ICP by preventing increases in intrathoracic and venous pressure, commonly associated with coughing, straining, and endotracheal suctioning. If needed, patients with critically elevated ICP should be pretreated with an intravenous bolus of a muscle relaxant or endotracheal lido-caine before airway suctioning is performed. Barbiturate coma remains a treatment option in individual patients when all other forms of ICP control have failed, although few studies have assessed the outcomes of this subgroup of ICH patients with ICP that is refractory to all other forms of therapy (49). Common complications of barbiturate coma include hypotension, predisposition to infections, cardiac depression, paralytic ileus, and coagulopathy. Less-studied forms of treatment for elevated ICP include systemic hypothermia and, in certain cases, decom-pressive craniectomy (50,51). Possible indications for emergency decompressive craniotomy are reviewed in Chapter 31.

Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

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