Pediatric Anesthesia Outside the Operating Room

Anesthesiology teams care for children in diverse locations, including diagnostic and interventional radiology, gastroenterology and pulmonary endoscopy suites, radiation oncology units, and cardiac catheterization laboratories. To provide safe, high-quality care, anesthesiologists working in these environments must understand the unique environmental and perioperative considerations and risks involved with each remote location and patient population. Once these variables are addressed, anesthesia and procedural teams can coordinate to ensure that patients and families receive the same high-quality care that they have come to expect in the operating room. This article also describes some of the considerations for anesthetic care in outfield locations.

Key points

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Each location in which anesthesia may be provided outside the operating room has specific procedural and logistical challenges. These challenges must be accounted for in making a plan for safe, high-quality anesthesia.
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Monitored anesthesia care or anesthesia with a natural airway is more likely to be administered in a non–operating room environment compared with an operating room.
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Procedures requiring anesthesia outside the operating room vary in their length, need for immobility, presence of painful stimuli, and procedural risk; anesthetic plans need to vary to accommodate these differences.
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In some remote locations, risk stratification regarding patient selection, planned intervention, involved staff or resources, and postoperative disposition must be considered.
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Patient monitoring is more likely to be remote, which may involve the potential for delay in recognition of and intervention for adverse events, placing the patient at increased risk of harm.

Anesthetic management in off-site locations

When planning an anesthetic for a non–operating room procedure, several factors should be considered. Procedures can vary in length and may require patient immobility and perhaps intervals of apnea. Painful stimuli may or may not be expected, and access to the patient may be limited. Anesthetic considerations may vary depending on these features. Table 1 lists several types of procedures and these characteristics. Other considerations include patient comorbidities and their relative severity and stability, the skill and comfort level of the anesthesia providers, distance from the operating room, available emergency response systems, and whether it will be necessary to transport the patient under anesthesia from one location to another or even from one facility to another. ^, National Anesthesia Clinical Outcomes Registry data show that monitored anesthesia care and general anesthesia with an unsecured airway are more common in non–operating room anesthesia compared with the main operating room. The most important aspect of choosing an anesthetic is a collegial discussion with the proceduralist to ensure that the planned anesthetic is safe for the patient and compatible with procedural goals.

Table 1

Types of non–operating room procedures

Procedure Type	Procedure Length ^a	Painful	Need for Immobility	Access to Patient During Procedure
Diagnostic radiology; ie, CT scan	Short	−	+	+/−
Diagnostic radiology; ie, MRI, nuclear medicine	Long	−	+	−
Interventional radiology	Variable	+	+/−	Limited
Cardiac catheterization	Variable	+/−	+	Limited
GI procedures	Short	+	+/−	+
Radiation oncology	Short but frequent repeats	−	+	−

Abbreviations: CT, computed tomography; GI, gastrointestinal.

a Short, less than 1 hour; long, greater than 1 hour.

Diagnostic radiology

Diagnostic radiology, consisting of radiography, fluoroscopy, MRI, computed tomography (CT), and nuclear medicine scans, comprises the largest proportion of pediatric outfield anesthesia. These painless scans require a motionless patient for acceptable image quality. Radiology departments have made great progress in helping patients avoid sedation for diagnostic scans. The technique of feed and wrap allows many neonates to avoid anesthesia for scans, reducing both the immediate sedation risk and the potential for anesthetic neurotoxicity. The important role Child Life specialists and prescan patient preparation in helping children successfully complete scans without sedation cannot be overemphasized.

When anesthesia is required, procedures can often be performed while the child is deeply sedated with propofol, dexmedetomidine, or a medication combination. ^, Apnea is occasionally required, necessitating intubation. If the anesthesiologist is concerned about anesthetic risk when a long scan is requested in a child with medical comorbidities, a conversation between the radiologist and anesthesiologist can clarify the relative risks of radiation and anesthesia and the need for a particular imaging modality; it is possible that a shorter nonsedated scan, such as CT, may be used, or that the MRI sequences can be decreased. ^, Overall, anesthesia and sedation for diagnostic radiology is very safe. The Wake Up Safe database focusing on pediatric anesthesia shows a 0.05% incidence of adverse events ( Table 2 ). The Pediatric Sedation Research Consortium, which reports sedation data from multiple physician specialties, reports a serious adverse event rate of 0.3% to 0.9% for diagnostic radiology. ^, It is common to combine several diagnostic scans or minor procedures into 1 anesthetic. Wake Up Safe data show that transport of patients under anesthesia increases risk ; this risk must be carefully considered when planning a combination procedure.

Table 2

Location of perioperative adverse events from the Wake Up Safe database

From Uffman JC, Tumin D, Beltran RJ, Tobias JD. Severe outcomes of pediatric perioperative adverse events occurring in operating rooms compared to off-site anesthetizing locations in the Wake Up Safe Database. Paediatr Anaesth. 2019;29(1):38-43; with permission.

Location	Severe AEs ^a(n = 819)	Less Severe AEs (n = 775)
Operating room	610 (74%)	622 (80%)
Off-site location ^b	209 (26%)	153 (20%)
CT scan	12 (1%)	5 (0.7%)
Cardiac catheterization	118 (14%)	80 (10%)
Endoscopy suite	17 (2%)	4 (0.5%)
Interventional radiology	26 (3%)	25 (3%)
MRI	30 (4%)	33 (4%)
Nuclear medicine	1 (0.1%)	1 (0.1%)
PET scan	0	2 (0.3%)
Radiation oncology	1 (0.1%)	2 (0.3%)
Sedation unit	2 (0.2%)	1 (0.1%)
Treatment room	2 (0.2%)	0

Abbreviation: AEs, adverse events.

a AEs resulting in temporary, severe, or permanent severe harm, death, or escalation of care.

b Percentages of specific out of operating room (OOR) locations listed here add up to total percentage of all OOR locations shown in this row.

Advanced diagnostic imaging

PET/MRI and PET/Computed Tomography

PET/MRI in the pediatric setting is an emerging modality that has seen increasing investigation and clinical application; at this point, initial operational and logistical costs limit this modality mainly to tertiary care hospitals. Oncologic investigations remain one of the most common applications of PET/MRI, and reports have shown favorable application for staging and treatment planning in many cancer types. PET/MRI combines the excellent soft tissue contrast of MRI with complementary physiologic information supplied by PET. When paired with MRI, PET/MRI yields certain advantages compared with conventional PET/CT, which include superior soft tissue imaging and the potential decreased need for multiple anesthetics if both PET/CT and MRI are required. Another major advantage of PET/MRI in the pediatric population is a 70% to 80% dose reduction in radiation exposure compared with PET/CT ^, ^, ; this may have a significant impact on total cumulative radiation exposure associated with serial imaging to monitor disease progression. In general, PET/MRI in the pediatric population is clinically indicated whenever a PET scan is required. Although combined scans have required prolonged time under anesthesia, improvements in imaging are reducing scan and anesthesia time for these procedures. Because it brings significant research interest, PET/MRI units may be located in proximity to a research and cyclotron center (ie, investigation of radionuclide tracers), which may require significant anesthesia planning and logistical coordination.

Magnetoencephalography

Magnetoencephalography (MEG) has played an increasing role in the management of medically intractable epilepsy. MEG records magnetic fields generated by passive or provoked synchronized neuronal activity. MEG’s clinical advantages include (1) the ability to localize foci in patients with MRI-negative epilepsy, (2) the capacity to differentiate between focal and multifocal disease, (3) the potential to avoid the risks of invasive phase 2 confirmation (ie, subdural grid placement), and (4) the ability to localize seizure foci with respect to eloquent areas of the brain (ie, motor cortex, areas for expressive language), which could potentially alter surgical approach. When coregistered with MRI, termed magnetic source imaging, the stereotactic data obtained can provide three-dimensional information crucial to presurgical epilepsy evaluation.

Sedation or general anesthesia for adequate clinical MEG-electroencephalography recording has been suggested by the America Clinical MEG Society’s Clinical Practice Guidelines. Because the postsynaptic potential of neurons is measured in the femtotesla range, MEG is performed in a magnetically shielded room (MSR), composed of mu-metal and aluminum, which diverts lower and higher frequencies, respectively. Anesthesia equipment and monitors create additional electromagnetic interference, so extensions of breathing circuits, monitoring lines, and infusion tubing are fed into the MSR via portholes and patient monitoring occurs remotely. Because MRI may also be required in sequence with MEG, transport concerns and magnetic field precautions should be anticipated. The anesthesia team should be prepared to manage the high likelihood of seizures encountered in this remote location.

There are limited data regarding the ideal anesthetic management for MEG. Anesthetic regimens that excessively induce or suppress interictal epileptiform activity or expand the region of epileptiform foci should be avoided. For example, Szmuk and colleagues reported that midazolam as premedication was associated with a high MEG failure rate versus chloral hydrate (73% vs 5.8%). Despite potential anticonvulsant properties at higher concentrations, propofol-based anesthesia for successful MEG recording has been described, with fewer artifacts reported when using lower infusion rates (ie, <100–150 μg·kg ⁻¹ ·min ⁻¹ ) supplemented by opiates or other adjuncts. ^, Case reports also describe etomidate infusions for successful MEG sedation. Dexmedetomidine has shown promise as an effective anesthetic in MEG sedation with no reported effect on interictal activity and is used in many centers. ^, Larger, prospective controlled studies examining a variety of anesthetic protocols may better identify the ideal anesthetic management for pediatric MEG patients in an outpatient setting.

Interventional radiology

Interventional radiology (IR) procedures for children can range from short procedures such as biopsies and drain placements to interventional or neurointerventional treatment of complex vascular anomalies lasting up to 12 hours. ^, In trauma and CF-associated hemoptysis, IR is used for rapid control of hemorrhage. ^, Catheter-delivered chemotherapy as well as cryoablation and radiofrequency ablations are being used in oncology patients. ^, IR physicians are also consulted for the placement of challenging long-term venous access. In the authors’ experience, up to 50% of procedures in IR are same-day add-ons, and these tend to involve patients with American Society of Anesthesiologists (ASA) physical status III or higher, limiting the time available for preoperative assessment. Safety data specific to pediatric IR are sparse. The Wake Up Safe database shows that 3% of severe adverse events were occurring in IR, although incidence data are lacking in this analysis (see Table 2 ).

A small amount of patient movement may be tolerable for short procedures away from vital structures, whereas more complex procedures generally require intubation and prolonged immobility. With the exception of trauma, blood loss is unlikely, although adequate intravenous access for hydration to offset the diuretic effect of contrast and sclerosant-associated hemoglobinuria is necessary. Reactions to contrast are anaphylactoid and require treatment similar to that for true anaphylaxis. Patients who have previously reacted to contrast require pretreatment with antihistamines and steroid before repeat exposure. Postoperative care of IR patients should include consideration of whether the patient needs to remain supine in the recovery room after solid organ biopsy or femoral artery access; if distraction does not suffice, supplementation with benzodiazepines or alpha-2 agonists such as dexmedetomidine may be helpful. ^, Postprocedure disposition should be discussed between the IR physician and the anesthesiologist to determine the appropriate level of care. Similarly, some procedures may be considered to be too high risk for off-site care (eg, patients with a difficult airway or mediastinal mass), and it may be necessary to move a procedure to the operating room for better access to support and emergency resources.

Radiation oncology

Radiation Therapy: Photons and Protons

Fractionated radiotherapy plays an essential role in multimodal management of early-stage or late-stage malignancy. Ionizing radiation is delivered in the form of photons (x-rays, γ-rays) or particle radiation (ie, proton therapy) using precise targeting systems. ^, Treatments are typically divided into 20 to 33 short sessions or fractions, which occur daily or twice daily over 4 to 6.5 weeks; the protracted course allows healthy cells to repair inadvertent DNA breaks and minimize radiation toxicity. Treatments are painless, but children must lie completely motionless alone in a vault, sometimes confined by a mask or restraint. Despite methods to avoid sedation through Child Life specialists, toys or award systems, or distraction devices such as the AVATAR (audiovisual-assisted therapeutic ambience in radiation therapy [RT]) system, anesthesia may still be required.

The initial encounter is focused on creation of immobilization devices (ie, thermoplastic mask, vacuum-formed cushion) for daily positioning, placement of reference markers (often small tattoos), and CT imaging in the immobilization device for treatment planning. Because head and neck treatments typically require a mask, vigilance to ensure proper head position during mask creation is critical, because this fixed airway position will be encountered during subsequent procedures. Sometimes, positioning for treatment makes spontaneous ventilation difficult, as in head flexion for craniospinal treatment. At 1 author’s (C.T.S.) institution, holes are cut to allow for airway access and the cut end of a laryngeal mask airway is placed between the teeth during CT simulation to replicate use of an advanced airway for future treatments if needed. Mask fit may become difficult over time because of weight gain from steroid treatment, and repeat simulation with mask creation may ultimately be required.

Anesthetic management for these procedures has evolved. Ketamine sedations were associated with a 23% to 24% incidence of complications and included uncontrolled patient movement, sialorrhea, hallucinations, and slow recovery. As propofol sedation has been adopted, review of safety data has revealed a trend toward fewer complications. An international, multi-institutional survey of 15,000 proton therapy anesthetics per year revealed that 72% of children less than 4 years of age received general anesthesia, with intravenous propofol used in 57% of procedures, and sevoflurane with a laryngeal mask airway used in 36% of procedures.

Safety data for pediatric sedation in RT are limited to individual institutions or smaller numbers of patients. Complication rates of 0.01% to 3.5% ^, ^, have been reported, with airway complications being most prevalent. ^, Anghelescu and colleagues’ retrospective review of 3833 anesthetics in 177 patients reported an increased incidence of complications during simulation sessions, suggesting that the required head manipulation, repositioning, and need for additional transport could be contributory. Christensen and colleagues’ evaluation of the Wake Up Safe database identified 6 major adverse events. In 1 procedure, the process of mask molding was complicated by laryngospasm. In 3 cases of medication errors (ie, incorrect infusion pump programming), remote monitoring of equipment in poor lighting conditions may have prevented earlier recognition. Indwelling central venous access devices are common and can be accessed for daily treatments, but they must be treated with care whenever accessed. Line-related complications, including sepsis, thrombosis, infiltration, and dislodgement, were found in 15% to 23% of patients in early studies, with ports being less problematic than peripherally inserted central catheter lines. ^, ^, Collisions and clearance issues between patient, gantry, or couch are commonly reported in RT and stereotactic radiation surgery, ^, despite standard collision safety mechanisms, such as closed-circuit television, touch-guard sensors, and infrared detection. One study found that the use of 3 additional cameras resulted in a blind-spot reduction of up to 87% and 10-fold reduction in vault reentry. The use of multiple adjustable pan-tilt-zoom network cameras may increase sensitivity of patient monitoring in these environments and should be considered when assessing a new location that involves similar remote monitoring ( Fig. 1 ).

In some cases of neuro-oncologic malignancy, craniospinal irradiation (CSI) is used to treat subarachnoid disease spread. CSI’s target volume encompasses the calvarium and spinal canal, resulting in exit-dose irradiation of multiple tissues anterior to the spinal canal. Acute and late toxicities are correlated with the radiation sensitivity of tissue affected, target volume, and the treatment time course. ^, These conditions include pneumonitis and pulmonary fibrosis, neurocognitive defects, ototoxicity, impaired vertebral bone growth, cardiac damage, vascular disease, endocrine dysfunction, and late-onset secondary malignancies. ^, ^, ^, Pediatric patients are particularly susceptible to long-term toxicity compared with adults because of higher numbers of susceptible proliferating cells and a longer life expectancy at time of exposure. Although there is debate regarding the advantages of proton therapy, which may include reduction of secondary damage in CSI treatments, and the financial, logistic, and ethical issues associated with the transition from conventional photon therapy, the use of proton therapy has become a standard at some centers. ^,

Palliative Radiation Interventions

RT is occasionally used to alleviate the symptoms of advanced or metastatic disease, such as pain, dyspnea, bleeding, spinal cord compression or other neurologic sequelae, bowel or bladder dysfunction, or inability to eat. ^, Representing approximately 11% of RT procedures, these treatments are typically limited in terms of duration, field extent, and cumulative dose. Benefits of palliative RT include decreased medication side effects (ie, narcotics), reduced overall hospital stay, minimized need for invasive procedures, and improved routine life at home.

These cases present challenges to the anesthesia team, from a logistical as well as a clinical standpoint. Palliative patients can present with debilitating symptoms, such as intractable vomiting, respiratory compromise, coagulopathy, and unstable neurologic symptoms, which all create additional anesthetic risk and necessitate a higher level of postoperative care. It is important for providers to specify the intent of these treatments to parents, and this indication must similarly be considered in the anesthetic plan when weighing the utility and inherent risks of sedation.

Stereotactic Radiosurgery

Stereotactic radiosurgery (SRS) is used for the treatment of various benign (ie, arteriovenous malformations) and malignant intracranial lesions. SRS is indicated for treating unresectable tumors (ie, located deep in eloquent areas), tumors with recurrence after prior radiotherapy, or residual disease. In contrast with fractionated radiotherapy, which uses repeated small doses of radiation, SRS relies on the delivery of a single or limited number of large doses of radiation to a precisely localized target. Although data are limited, newer technologies in frameless SRS have shown precision similar to conventional frame-based radiosurgery, and may have applications to pediatric patients, especially patients for palliation. ^,

Frame-based SRS poses unique anesthetic challenges ( Fig. 2 ). Imaging, planning, and SRS treatment all occur during 1 session, requiring immobility and often prolonged wait times; general anesthesia is often required in young or uncooperative patients. Anesthetic considerations include multiple locations with their associated risks (ie, radiation and magnetic fields), frequent transfers, and possible intrafacility transport of the anesthetized patient in a bulky head frame, remote patient monitoring, unpredictable duration of treatment, and increased risk of positioning injury or hypothermia. Each site in the process (angiography and/or MRI suite, SRS procedure room, holding area) must be fully set up and prepared for pediatric anesthesia. A preinduction time-out with all involved members to discuss the sequence of diagnostic and interventional procedures, assess readiness of each location, and anticipate potential obstacles is essential for safety. Propofol-based intravenous anesthesia has the advantage of allowing transport while maintaining a titratable depth of anesthesia in variable locations. Use of portable monitors can expedite seamless monitoring and portable infusion pumps allow reliable delivery of intravenous anesthetic agents and carrier fluids.