Chapter 17 – Anesthesia for Neurointerventional Radiology

Chapter 17 Anesthesia for Neurointerventional Radiology

Mary Landrigan-Ossar

Introduction

Anesthesiologists caring for pediatric patients in the neurointerventional suite have many tasks. As experts in the physiology of anesthesia and its expected alterations during a proposed procedure, they are the final arbiters of whether a patient is medically prepared to undergo a procedure in an offsite location with limited access to backup. They coordinate the team in the procedure room, ensuring that every person regardless of their role is focused on patient safety and procedural success (in that order). They act as a psychological support to fearful patients and parents prior to the procedure. Only by successfully integrating all of these tasks can a consistently safe and successful pediatric neurointerventional service be facilitated.

For many anesthesiologists, the interventional radiology (IR) suite is a supremely undesirable anesthetizing location. With the currently rare exception of hybrid angiography operating rooms, IR is remote from the main operating rooms and is perceived as terra incognita for many reasons: unfamiliar staff and equipment, unfamiliar procedures, and greater patient acuity. This prejudice against the supposed terrors of IR must fall before the fact that it is increasingly utilized for the treatment of patients with neurosurgical pathology, particularly neurovascular issues.

This chapter deals with several common procedures that are encountered in a pediatric neurointerventional suite, with suggestions for their safe and effective management.

Case 1

An 8-year-old female with suspected moyamoya syndrome presents for diagnostic cerebral angiography in preparation for an upcoming craniotomy and pial synangiosis. She had experienced several seizures; magnetic resonance imaging (MRI) showed carotid narrowing concerning for moyamoya.

Diagnostic Angiography

Diagnostic cerebral angiography is the most common pediatric neurointerventional procedure. It is fortunately the procedure resulting in the least physiologic derangement. While noninvasive imaging such as computed tomography (CT) and MRI continually gains in sophistication, catheter-based angiography remains the gold standard for characterizing neurovascular pathology. Cerebral angiography may be used to investigate vasculature in the setting of hemorrhage, stroke, and vasculopathies such as moyamoya disease and after operative cerebrovascular interventions.

Preoperative Issues

Preoperative preparation for procedures in the neurointerventional suite is most safely accomplished when it mirrors preanesthesia workup for the main operating room. Consistent standards for chart review and the need for communication with consulting services will ensure that patients receive appropriate assessment and optimization before they arrive in radiology for their procedure. For uniformity throughout an institution, this is ideally accomplished by, or in close consultation with, the anesthesiology department. In a similar vein, anesthesia equipment should be as similar as practicable to that used in the operating rooms. Unfamiliar machines and monitors in a remote anesthetizing location increase user discomfort and the risk of error in an already challenging physical location (Figure 17.1).¹

Figure 17.1. Typical room configuration in interventional radiology, with anesthesiologist at some distance from the patient.

While simple cerebral angiography itself does not warrant anything more than a day surgical visit, careful consideration must be given to patient comorbidities that would increase patient risk with anesthesia and perhaps warrant pre- or postprocedure admission. For example, moyamoya disease risk is increased in patients with conditions including sickle cell disease, trisomy 21, and neurofibromatosis. Consultation with a patient’s specialty services to ensure preoperative medical optimization and consideration of the issues that go along with those conditions are necessary when planning for anesthesia.²

Intraoperative Management

Cerebral angiography is a relatively short procedure, usually taking less than 1 hour. Intermittent periods of apnea are ideal for suitable images. An emotionally mature teenager may be able to tolerate the procedure without sedation or with anxiolysis; deeper levels of sedation run the risk of a disinhibited patient, or a patient too sleepy to cooperate with breath holding. For this reason, it is common to perform the procedure on younger or more anxious patients with general anesthesia and an endotracheal tube. Should anesthesiologists determine that sedation is the safest choice for a patient, it is essential that they discuss this with their neuroradiology colleague to determine if this will result in acceptable image quality.

When anesthetizing any patient with potential cerebrovascular disease, careful consideration must be given to blood pressure and fluid management. Especially on induction of anesthesia, one must avoid hypotension that can put patients with a vasculopathy such as moyamoya at risk for cerebral hypoperfusion. It may be advisable to schedule such patients early in the day to minimize their fasting time. On the other hand, acute hypertension that could precipitate catastrophic bleeding in an unstable aneurysm or arteriovenous malformation (AVM) must also be avoided. An arterial line for this short procedure is generally unnecessary if reliable readings can be obtained from a noninvasive blood pressure cuff. Normocapnia is desirable in the vast majority of cases, and any proposed acute hypocapnia should be discussed with the neuroradiologist. While the risk of significant bleeding is extremely low, intravenous access that is sufficient to allow for adequate hydration is necessary. Normo- to slight hypervolemia will offset the diuretic effect of nonionic contrast medium and reduce the slight chance of any contrast-induced nephropathy.

Postoperative Concerns

Complications after cerebral angiography in pediatric patients are quite rare. Several series from high volume pediatric centers have demonstrated rates less than 0.4% with experienced neuroradiologists.³ The most common of these rare problems is bleeding or hematoma at the site of femoral puncture. Neurologic or vascular problems as a result of catheterization are very rare, as are nephrologic consequences of contrast administration.

One major challenge for a pediatric patient after a cerebral angiogram is that they must lie flat for several hours to ensure hemostasis of the femoral artery. While behavioral techniques and the presence of parents can help reassure and distract an older or more cooperative child, medications have a role for younger or less cooperative children. Deep extubation when feasible and a period of quiet sleep in the recovery area with narcotics, benzodiazepines, or α-2 agonists as adjuncts can make this experience much less stressful. Pain after the procedure is minimal, and most patients are discharged from the recovery room needing only nonopiate pain medications thereafter.

Case 2

A 3-day-old male is scheduled to come to IR for embolization of a massive vein of Galen AVM (Figure 17.2). He was born in high-output heart failure and is currently intubated and being treated with vasopressor infusions.