Managing Increased Intracranial
Pressure
Introduction
• The cranium is a rigid compartment.
• Contains the brain, vessels and cerebrospinal fluid.
• Can not expand after closure of the skull sutures.
• It’s ability to accommodate volume changes is limited.
Cranial Contents
Monroe-Kellie Doctrine
Monroe-Kellie Doctrine
Presentation
• Headache.
• Visual Symptoms.
• Vomiting.
• Altered level of consciousness.
• Papilledema.
Etiology
• Space occupying lesions.
• Trauma.
• Hydrocephalus.
• Meningitis.
• Bleeding.
• Idiopathic intracranial hypertension.
Effect on Cerebral Perfusion
• Normal blood flow to the grey matter is 75 ml/100 gm/min, and 45
ml/100 gm/min.
• Ischemia ensues at 20 ml/100 gm/min.
• Irreversible damage at 10 ml/100gm/min.
• Cerebral Perfusion Pressure is the most significant measure of blood
flow.
Effect on Cerebral Perfusion
• CPP: the effective blood pressure gradient across the brain.
• Calculated as: CPP= MAP-ICP.
*CPP: cerebral perfusion pressure, MAP: mean arterial pressure, ICP: intracranial pressure.
• Increased ICP decreases CPP, leading to ischemia.
Cerebral Autoregulation
• The ability of the brain to maintain blood flow across a wide range of
CPPs.
• Increases in CPP cause vasoconstriction and vice versa.
• CO2 tension controls autoregulation.
• Hyperventilation leads to decreased CO2 tension leading to
vasoconstriction.
Cerebral Auto regulation
Failure of Autoregulation
• Autoregulation is limited to CPPs ranging from 50-150 mmHg.
• Failure of autoregulation occurs when CPP exceeds 150 mmHg.
• Blood flow increases and leads to vasogenic edema.
• Hypotension may contribute to worsening of the process. (CPP=MAPICP).
Monitoring ICP
• ICP is the most important indicator of morbidity and mortality.
• Indicated in patients presenting with head trauma and spontaneous
subarachnoid hemorrhage, as well as a GCS score between 3-8 and
abnormal CT scans.
• Two main techniques of monitoring: intraventricular and
intraparenchymal.
Monitoring ICP
ICP waveforms
ICP Waveforms
Treatment
• Aims at decreasing ICP and optimizing perfusion to brain tissue.
• Utilizes auto regulatory mechanisms to achieve the required balance.
• Several targets of therapy lead to synergistic effect on ICP.
Non-pharmacological
Head Elevation
• Rapid, easy and effective.
o
• Keeping the head elevated at 30-45 .
• Uses the force of gravity to promote venous drainage.
• Head must be forward facing.
• Contraindicated in hypovolemic patients.
Head Elevation
Hyperventilation
• Leads to decreased blood flow to the brain by vasoconstriction.
• Rapidly decreases ICP.
• Target Pco2: 30-35 mmHg.
• Sustained hyperventilation may lead to ischemia.
• Target: Cerebral blood volume.
Hyperventilation
Hypothermia
• Core temperature target of 32-35o for a few days.
• Controversial, but more centers are starting to embrace it.
• High incidence of manageable complications.
• Efficacious.
• Eurotherm3235 trial currently underway.
Hypothermia
Hyperbaric Oxygen
• Class I evidence suggests decreased mortality.
• Class IV evidence suggest acute decrease in ICP.
• Functional outcome controversial.
Hyperbaric Oxygen
Summary of Non- Pharmacologic Management
Pharmacologic Management
Sedation
• Intubation indicated when the patient is unable to protect airway or
breath spontaneously.
• Propofol is the agent of choice due to short action and effect on brain
metabolism.
Target: decreasing cerebral metabolism.
Sedation
Mannitol
• Osmotic agent most commonly used in high ICP.
• Effect is two-fold:
1- Creation of osmotic gradient which increases intravascular volume,
leading to vasoconstriction.
2- Cumulative osmotic gradient causes interstitial fluid to enter
vasculature leading to decreased edema.
Mannitol
• Given in boluses of 0.25 g to 1 g/kg at 4 to 6-hour intervals.
• Most useful in the initial 48 to 72 hours.
• Monitoring of kidney functions, urine osmolality and electrolytes
needed.
Mannitol
Hypertonic Saline Therapy
• Emerging as an effective alternative to mannitol.
• Similar efficacy and mechanism of action.
• May be used beyond 72 hours.
• Superior to mannitol in hypovolemia and hypotension.
Hypertonic Saline Therapy
• Boluses of 30 ml of 23.4% hypertonic saline
• Infused over 15 minutes through a central line.
• Sustained use may lead to electrolyte imbalances.
Hypertonic Saline Therapy
Barbiturate Coma
• Controversial.
• Drug of choice is Thiopental.
• Requires intensive monitoring of vitals signs.
• May lead to hypotension.
Barbiturate Coma
Opioids
• Conflicting evidence, mostly due to use along with other ICP lowering
agents.
• Used alone, they are thought to increase ICP and CBF.
• Fentanyl most commonly used, with remifentanyl emerging as a
substitute.
Opioids
Corticosteroids
• Evidence against use.
• May increase mortality.
• Some agents have shown promising results.
Corticosteroids
Progesterone Therapy
• Potentially neuroprotective, with very weak evidence on outcome.
• No effect on ICP, possible better functional outcome.
Progesterone Therapy
Summary of Pharmacological Therapy
Summary of Pharmacological Therapy
Surgical Management
CSF Drainage
• Decreases CSF volume.
• Allows for ICP monitoring.
CSF Drainage
Decompressive Craniectomy
• Bifrontal craniectomy or hemicraniectomy including the frontal
temporal and parietal bones.
• Cancels the Monroe-Kellie Doctrine and allows the brain to expand.
• Evacuation of an underlying hematoma if present.
• Remains controversial due to lack of class I evidence.
Decompressive Craniotomy
References
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