AANN Core Curriculum, 7th Edition, Ch. 10 Intracranial Pressure Management: Digital Version-Chapter 10

Chapter 10

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Intracranial pressure (ICP) reflects the balance among brain tissue, cerebrospinal fluid (CSF), and blood volume under the Monro–Kellie doctrine. Normal supine ICP is 0–15 mmHg; intracranial hypertension is generally defined as ICP above 20 mmHg for at least five minutes. Adult treatment is commonly recommended above 22 mmHg, with pediatric targets generally below 20 mmHg. Elevated ICP can cause secondary brain injury and herniation.<br /><br />Major causes include brain masses, hematomas and edema; impaired CSF flow or absorption causing hydrocephalus; increased cerebral arterial blood volume from factors such as seizures, fever, hypoxia or hypercapnia; and impaired venous drainage. Idiopathic intracranial hypertension is another cause. Monitoring is used when ICP is suspected or anticipated, particularly in severe traumatic brain injury (TBI), and may also guide care in selected cases of hemorrhage, subarachnoid hemorrhage, hydrocephalus, hepatic failure and other conditions.<br /><br />Symptoms include altered consciousness, headache, nausea or vomiting, visual changes, seizures, pupillary or cranial nerve abnormalities, and motor dysfunction. Late signs may include Cushing’s triad: hypertension with widened pulse pressure, bradycardia and abnormal breathing. Infants may have poor feeding, irritability, bulging fontanels or separated sutures.<br /><br />The normal ICP waveform has three peaks: P1 (arterial pulse), P2 (tissue compliance) and P3 (venous/aortic-valve component). A higher P2 relative to P1 can suggest reduced compliance. A waves are severe, sustained pressure plateaus that may precede herniation; B waves reflect rhythmic pressure fluctuations and may precede A waves; C waves are smaller and faster.<br /><br />Management aims to prevent secondary injury and maintain cerebral perfusion. Interventions include ensuring oxygenation, draining CSF when indicated, maintaining appropriate blood pressure and cerebral perfusion pressure, and using hypertonic saline or mannitol for raised ICP. Sedation, analgesia, seizure control, fever prevention, appropriate positioning and minimizing coughing, straining and other ICP-provoking activities can also help. Monitoring must account for the patient’s examination, ICP trends, device accuracy and treatment effects.

Keywords

intracranial pressure

intracranial hypertension

cerebrospinal fluid

Monro-Kellie doctrine

hydrocephalus

traumatic brain injury

Cushing triad

brain herniation

hypertonic saline

mannitol