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A 3-month-old, former 33-week-gestation premature, male infant presents with a history of increasing irritability and lethargy and vomiting of 2 days’ duration. The infant has a history of a grade III intraventricular hemorrhage in the newborn period that required a ventriculoperitoneal (VP) shunt. The neurologist and neurosurgeons have already obtained an x-ray and have determined that the existing VP shunt is blocked. He is scheduled for an emergency VP shunt revision.
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PREOPERATIVE CONSIDERATIONS
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Hydrocephalus is not a disease in itself but a consequence of a disease process. In the neonatal period, the most common causes for hydrocephalus are anatomic anomalies associated with myelodysplasia and prematurity (intraventricular hemorrhage). Other causes include obstruction or a mass effect caused by tumors or a decrease in cerebrospinal fluid resorption secondary to scar or fibrin deposition postcraniotomy. Patients present with bulging fontanelles and ophthalmoplegia (in the newborn period), headaches, irritability, lethargy, and vomiting. This can progress to seizures and finally to herniation of the brain stem.
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The presence or absence of increased intracranial pressure (ICP) must be assessed prior to induction. If increased ICP is present, no premedication should be given. Other factors to consider should be pulmonary status (especially if the patient is a former premature infant), seizure history and medications, and physical limitations.
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ANESTHETIC MANAGEMENT
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In patients with longstanding hydrocephalus, the head circumference will be increased. Accessing the oral cavity with the laryngoscope may be challenging if the occiput causes extreme flexion of the head, so consider elevating the patient’s shoulders and/or torso to put the head in a neutral position.
Induce anesthesia via IV or inhalation, if a full stomach is not a consideration.
If the patient has not been fasted appropriately or is vomiting, then consider a rapid-sequence induction using a nondepolarizing muscle relaxant such as rocuronium (1 mg/kg IV) rather than a depolarizing muscle relaxant to prevent an increase in gastric pressure and vomiting and an increase in intracranial pressure. The use of a depolarizing muscle relaxant is not absolutely contraindicated and should be considered if the need for immediate control of the airway outweighs the risks of a transient increase in intracranial pressure.
In the premature infant especially, use the lowest possible fraction of inspired oxygen (FiO2) needed to maintain oxygen saturations above 90% to minimize the risk of retinopathy of prematurity.
Avoid hypercapnia and a halogenated agent, especially in the patient with an elevated ICP, until the cranium is opened.
Consider using an intravenous anesthetic rather than an inhalational anesthetic to avoid vasodilation.
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POSTOPERATIVE CONSIDERATIONS
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The premature and former premature infant is at risk for postoperative apneic episodes for a period lasting up to 60 weeks postconception and should have cardiorespiratory monitoring for 24 hours postoperatively.
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