Considerations for non-operating room anesthesia (NORA)

INTRODUCTION — Advanced technologies have resulted in development of imaging techniques for diagnosis and interventional treatment of various medical conditions and injuries that once required open surgical procedures in an operating room (OR). Patients with significant comorbidities may require complex or prolonged procedures in these hospital settings that are remote from the main OR area. For these reasons, the need for non-operating room anesthesia (NORA) care is increasing in locations such as interventional radiology (IR), transesophageal echocardiography (TEE), electrophysiology (EP), interventional cardiology, endoscopy, magnetic resonance imaging (MRI), computed tomography (CT), and interventional pulmonary suites [1,2].

Special preparations are typically necessary to provide anesthetic care in these locations. This topic will review general considerations for NORA care of patients undergoing various procedures in IR suites, TEE suites, and other locations that are distant from the main OR. Additional details regarding specific considerations that are relevant in certain locations are discussed in separate topics:

●Intracranial neurovascular procedures (see "Anesthesia for endovascular therapy for acute ischemic stroke in adults" and "Anesthesia for intracranial neurovascular procedures in adults")

●Endovascular aortic repair or peripheral arterial balloon angioplasty, embolization, or thrombolysis (see "Anesthesia for endovascular aortic repair" and "Anesthesia for infrainguinal revascularization")

●MRI or CT (see "Anesthesia for magnetic resonance imaging and computed tomography procedures")

●Procedures in the EP suite (see "Anesthetic considerations for electrophysiology procedures")

ANESTHETIC CHALLENGES IN NON-OPERATING ROOM LOCATIONS — Challenges in providing anesthetic care for procedures performed in interventional radiology (IR), transesophageal echocardiography (TEE), electrophysiology, cardiac catheterization, endoscopy, magnetic resonance imaging (MRI), computed tomography (CT), and interventional pulmonary suites include distance from the main operating room area, access to equipment, ergonomics, staffing, and communication issues (table 1) [1-3]. We agree with consensus recommendations developed by the Anesthesia Patient Safety Foundation (APSF) for Safe Conduct of Non-operating Room Anesthesia (NORA) [4]. These include guidelines for preprocedure evaluation and postanesthesia recovery; standards for anesthesia and monitoring equipment, supplies, and medications; need for interdisciplinary communication during the procedure; and immediate availability of emergency equipment, drugs, and crisis manuals appropriate for the patient population and procedures in these locations.

Preparation of anesthetic equipment — The American Society of Anesthesiologists (ASA) and the APSF have provided recommendations for management of patients receiving anesthetic care in off-site locations [4,5]. Preparation typically requires extra time to complete the following tasks [4]:

●Remote settings with permanent anesthesia equipment – The anesthesia provider must establish familiarity with the anesthesia machine, monitors, medication cart, and oxygen and suction sources that are present in a remote location. Such equipment often differs from that used in the main ORs. In many institutions, new anesthesia equipment is installed in the main OR area, while older equipment with different components and monitors is rotated to off-site locations. (See "Anesthesia machines: Prevention, diagnosis, and management of malfunctions", section on 'Malfunction of anesthesia machine components' and "Anesthesia machines: Prevention, diagnosis, and management of malfunctions", section on 'Malfunction of integrated anesthesia monitors'.)

●Remote settings with no anesthesia equipment – Anesthesia personnel must transport equipment such as the anesthesia machine, monitors, warming devices, and other equipment, as well as anesthetic agents and other medications to the remote location. Potential clinical problems that might require special anesthetic equipment or specific pharmacologic agents must be anticipated. Due to the remote location, there is a high likelihood of a significant delay if additional items or assistance is needed.

Furthermore, if inhalation anesthetic agents are to be administered via the anesthesia machine, the availability of compatible connections from the scavenger system to waste anesthesia gas disposal (WAGD) outlets or medical vacuum outlets is a consideration in some off-site locations [6]. WAGD outlets are typically only found in operating or procedure rooms where anesthesia care is routinely provided. Waste gas hoses from anesthesia machines may not be compatible with the medical vacuum outlets found in other locations (picture 1). Potential solutions for these issues when anesthesia machines are used in locations outside the ORs include (see "COVID-19: Intensive care ventilation with anesthesia machines", section on 'Unique safety issues'):

•Refrain from use of inhalation anesthetics – If the anesthesia machine has an open scavenger system that is not connected to a WAGD or medical vacuum outlet, refrain from administering inhalation anesthetic agents. No modifications are necessary if there are no waste anesthetic gases to be scavenged.

•Modify an anesthesia machine with a closed scavenger system – If the anesthesia machine has a closed scavenger system (a reservoir bag), modifications are necessary to prevent inappropriate continuous positive airway pressure, excessive positive end-expiratory pressure (PEEP), and high peak pressures even if no inhalation anesthetic agent is used [6]. Options include disconnecting the scavenger system from the hoses coming from the breathing system and ventilator, or removing the reservoir bag altogether (picture 2).

•Special preparations for planned use of inhalation anesthetics – Regardless of whether the anesthesia machine has an open or closed scavenger system, scavenging will be required if an inhalation anesthetic agent will be used. The anesthesia machine must be connected to an available WAGD or medical vacuum outlet. Alternate tubing or connectors or connection adapters may be necessary to make this connection.

Also, if high fresh gas flow will be used, then the scavenger system will require high vacuum flow, and the scavenger suction must be adjusted upward to ensure proper function.

Positioning of anesthesia equipment — Many off-site suites are not designed for delivery of anesthetic care, and there is no specific space allocated for anesthesia equipment [4]. After transport of the anesthesia machine, monitors, and medication cart to the location, anesthesia personnel typically must position these bulky items in relation to radiology or other equipment that is already located within the suite. Circuit extenders for the anesthesia machine may be necessary to facilitate ventilation and monitoring respiratory gases (eg, end-tidal carbon dioxide [ETCO₂], expired inhaled anesthetic concentrations), particularly if the patient is to be moved into an imaging tube for MRI, CT, or other radiographic imaging. Extension tubing for the patient’s intravenous (IV) lines may also be necessary in these settings (see "Anesthesia for magnetic resonance imaging and computed tomography procedures", section on 'Positioning in the MRI suite'). After induction of anesthesia and prior to draping, we move the fluoroscopy machine through its full range of motion, checking that all lines and tubes are out of the way.

After final positioning, the anesthesia provider may not have easy access to the anesthesia machine and monitors or to the patient. Ideally, the room setup will allow the anesthesiologist to view both the patient and the anesthesia machine and monitors. In some off-site locations, direct observation is possible. In other instances, patient and monitors are viewed from a shielded control room via a video monitor.

In all settings, IV anesthetic agents, airway equipment, and emergency drugs should be immediately accessible as interventions such as increasing or decreasing anesthetic depth or managing an airway or cardiopulmonary emergency may be suddenly necessary. (See 'Management of emergencies' below.)

Need for interdisciplinary communication — The multidisciplinary team members including the anesthesiologist, subspecialized nursing personnel, technicians, and interventionalist (eg, radiologist, cardiologist, gastroenterologist, pulmonologist) in many off-site locations may not work together regularly and may be unfamiliar with the procedures and techniques planned by the other [4]. For this reason, we discuss planned events in a preprocedure briefing. Issues include how and where anesthesia will be induced (eg, in the imaging room itself or in a separate induction room), how the patient will be transported to the imaging room and positioned, specific requirements for the imaging procedure (eg, periods of apnea for thoracic imaging), and where the patient will recover from anesthesia. As with briefings in an OR setting, availability and proper functioning of all necessary anesthetic and monitoring equipment is also verified [4]. (See "Patient safety in the operating room", section on 'Timeouts and briefing in the operating room'.)

Management of emergencies

Complications during elective cases — The ASA closed claims analysis has noted a higher incidence of malpractice claims for death after NORA care compared with OR settings [7]. Nonanesthesia personnel working in off-site settings are often unfamiliar with anesthetic care, particularly urgent or emergency interventions that may be necessary due to loss of control of the airway or cardiac arrest. Likewise, anesthesia personnel may be unfamiliar with life-threatening complications associated with the planned interventional procedure. Advance planning and strategies to manage such emergencies include:

●Ensure ready access to specialized resuscitative equipment that might be necessary for high-risk patients (eg, difficult airway cart, invasive monitoring equipment) by prior placement in the immediate vicinity of the off-site suite.

●Ensure ready availability of cognitive aids for specific emergency situations [4]. This is particularly important if personnel in the off-site location only rarely participate in crisis management for anesthesia-related emergencies [8]. (See "Cognitive aids for perioperative emergencies".)

●Prearrange communication protocols with anesthesiology and other specialized personnel outside the off-site location to ensure rapid response to an emergency call for assistance [4]. For pediatric cases, responding personnel should be subspecialized in pediatric resuscitation. (See 'Challenges during emergency cases' below.)

●Ensure a process for multidisciplinary review of emergency events (ie, debriefings). (See "Patient safety in the operating room", section on 'Debriefing'.)

Challenges during emergency cases — Additional challenges exist during anesthetic management of hemodynamically unstable emergency cases such as a patient with traumatic injuries:

●When there is lack of time for preparation due to emergency presentation, we request immediate help from anesthesia personnel for delivery of equipment and assistance with ongoing resuscitation. This may include insertion and monitoring of an intra-arterial and/or central venous catheter to administer medications, fluids, and blood transfusions. Trauma centers should have full monitoring capabilities and be stocked with routine and advanced airway capabilities, equipment for rapid transfusion, and a variety of catheters for intravascular and intra-arterial access in off-site locations. If necessary, the radiologist can assist with emergency placement of intravascular cannulae. (See "Anesthesia for adult trauma patients", section on 'General principles'.)

●Additional blood loss and unresolved hemodynamic instability may occur even after successful embolization treatment after a traumatic injury due to other injuries to visceral organs or major blood vessels. Arrangements for access to blood products without delay are particularly critical to provide adequate resuscitation of traumatically injured patients in an off-site location. (See "Anesthesia for adult trauma patients".)

Radiation risks

●Risks for anesthesiologists – In IR, CT, EP, and interventional cardiology suites, the anesthesia provider will likely be exposed to ionizing radiation. Dosimeter badges should be worn by anesthesiologists who are regularly exposed to radiation risks so that cumulative radiation exposure may be monitored [9].

Radiation dose is determined by (see "Radiation-related risks of imaging"):

•Distance – The amount of radiation to anesthesiologists decreases in proportion to the square of their distance from the source (ie, doubling the distance from the tube decreases the amount of radiation by a factor of four). Generally, the anesthesiologist should be physically located in an observation room distant from the source of radiation, or stand as far away as possible behind a portable shield and wear suitable shielding equipment, as noted below [9,10].

•Time – Anesthesiologists may be exposed to longer durations and higher doses of radiation than radiologists and other personnel during IR or CT imaging because the radiology team members can perform their duties within the shielded control room, while the anesthesiologist may be exposed during adjustments of doses of anesthetic agents or while troubleshooting monitoring equipment. In some cases (eg, a sedated patient with a potentially difficult airway), the anesthesiologist must remain by the patient's side at all times.

•Shielding – Availability of portable shields, lead aprons, thyroid collars, and eye protection should be ensured and used by all anesthesia personnel to mitigate risk [9,10]. Although lead aprons are always worn, the dose of radiation may become excessive over time.

●Risks for patients – Risks for all patients undergoing exposure to ionizing radiation are discussed in a separate topic. (See "Radiation-related risks of imaging".)

Specific risks for children are discussed separately. (See "Radiation-related risks of imaging", section on 'Children and adolescents' and "Ischemic stroke in children: Clinical presentation, evaluation, and diagnosis", section on 'CT safety considerations'.)

Due to potential risks for the fetus, potential for pregnancy is assessed in all women of childbearing age during the preanesthesia consultation. (See 'Preanesthesia evaluation' below and "Diagnostic imaging in pregnant and lactating patients", section on 'Fetal risks'.)

PREANESTHESIA EVALUATION — A member of the interventionalist team in the off-site location (eg, interventional radiologist or cardiologist) typically consults anesthesia personnel to determine what type of anesthetic care is recommended. The anesthesiologist reviews the pathology for which the procedure is being performed, the interventionalist's specific requirements for completion of the procedure, and patient-related factors that affect choice of anesthetic technique. (See "Preoperative evaluation for anesthesia for noncardiac surgery" and 'Selection of anesthetic technique' below.)

Patients undergoing interventional radiology (IR) procedures are often receiving care from a different in-hospital service or are referred for the procedure from an outside practitioner. In many cases, the anesthesiologist serves as a liaison between the interventionalist and the referring clinician (primary care clinician and/or other specialists) during the preprocedure evaluation. For elective cases, the anesthesiologist ensures that preprocedure medical status is optimal and that patient education regarding periprocedural expectations has been accomplished.

Special preparations are necessary for some patient-specific issues. Examples include:

●Need for prophylactic medications – Antibiotic and/or deep vein thrombosis (DVT) prophylaxis may be necessary in selected cases.

Prophylactic measures are taken if the patient has a history of allergic reactions to any agents that will be administered (eg, contrast material, protamine), or the agent is avoided. (See "Patient evaluation prior to oral or iodinated intravenous contrast for computed tomography", section on 'Prevention'.)

●Patients who are pregnant – Patients of childbearing age are assessed for the possibility of pregnancy. In patients who are known to be pregnant, the following considerations may be applicable:

•The anesthesiologist serves as a liaison between the interventionalist and the obstetrician.

•Preparations are made for fetal heart rate monitoring, if indicated, during and after the procedure. Immediate availability of an obstetrician is ensured if emergency cesarean delivery may become necessary.

•Preparations are made for management of a potentially difficult airway and aspiration risk in case immediate conversion to endotracheal intubation and general anesthesia becomes necessary. (See "Anesthesia for nonobstetric surgery during pregnancy", section on 'Preparation for anesthesia'.)

•Ideally, the patient’s position during the procedure should allow for uterine displacement to ensure optimal hemodynamics, while considering adequate access of the imaging equipment and the interventionalist. (See "Anesthesia for nonobstetric surgery during pregnancy", section on 'Positioning'.)

●Patients who are receiving palliative care – Some palliative procedures are performed in the IR suite (eg, gastrostomy tube placement in a patient with inability to swallow due to advanced amyotrophic lateral sclerosis causing significant bulbar weakness). Preoperative challenges for anesthetic care include:

•A full discussion of advanced directives with the patient, interventionalist, referring neurologist, and palliative care specialist is necessary, especially for patients requesting that general anesthesia with endotracheal intubation be avoided. The anesthesiologist serves as a liaison between the patient, family members, and these other specialists.

-If endotracheal intubation is an option, determine whether preparations for difficult airway management are necessary, as well as preparations for transport and further management in an intensive care unit in case weaning from controlled ventilation cannot be achieved. (See "Transport of surgical patients" and "Transport of surgical patients", section on 'Considerations for critically ill patients'.)

-If endotracheal intubation is not an option, ensure that preprocedure preparations are made for immediate availability of noninvasive ventilation support if this becomes necessary to achieve adequate oxygenation and ventilation in the IR suite (eg, continuous positive airway pressure, bilevel positive airway pressure, high-flow nasal cannulae oxygen delivery). (See "Modes of mechanical ventilation", section on 'Continuous positive airway pressure' and "Modes of mechanical ventilation", section on 'Bilevel positive airway pressure' and "Heated and humidified high-flow nasal oxygen in adults: Practical considerations and potential applications".)

●Selected severe comorbidities – Severe comorbid conditions may be present in some patients undergoing a percutaneous interventional rather than an open surgical procedure. As an example, for a patient with advanced cardiomyopathy who is undergoing radiofrequency ablation (RFA) of a primary adrenal tumor, the anesthesiologist:

•Ensures that the patient's preoperative coagulation parameters are within normal limits.

•Serves as a liaison to communicate directly with the referring endocrinologist and interventionalist to determine whether pretreatment with antihypertensive agents (eg, alpha and beta blockers) is adequate before this semi-elective procedure.

•Ensures preprocedure communication with a thoracic surgeon for emergency treatment of hemorrhage or a tension pneumothorax since inadvertent puncture of surrounding vascular structures or lung tissues is possible [11]. (See "Thoracostomy tubes and catheters: Indications and tube selection in adults and children", section on 'Tension pneumothorax'.)

•Prepares for invasive blood pressure (BP) monitoring since RFA of adrenal tumors is associated with hypertensive crises (defined as diastolic BP >120 mmHg and/or systolic BP >180 mmHg) due to release of catecholamines from the adrenal gland. In some cases, preparations are made to establish adequate central venous access for infusion of vasoactive agents (eg, nicardipine).

ANESTHETIC MANAGEMENT

Monitoring — Standard American Society of Anesthesiologists (ASA) monitoring (eg, electrocardiography [ECG], pulse oximetry [SpO₂], noninvasive blood pressure [NIBP] cuff measurements), and continuous capnography to monitor end-tidal carbon dioxide (ETCO₂) is necessary to rapidly diagnose respiratory or cardiovascular instability (table 2) [4]. Temperature is monitored, and patient warming may be necessary in some cases. During general anesthesia, intermittent airway pressures and volumes are monitored in addition to standard ASA monitoring. (See "Basic patient monitoring during anesthesia", section on 'Standards for monitoring during anesthesia'.)

Positioning the patient — As in cases performed in an operating room (OR), it is important to consider prevention of nerve injuries during procedures performed in other locations [12]. If general anesthesia is planned, a trial position may be tested before induction. (See "Patient positioning for surgery and anesthesia in adults".)

Selection of anesthetic technique

General considerations — Monitored anesthesia care (MAC) with sedation, regional or neuraxial anesthesia, or general anesthesia may be selected depending on procedure-specific and patient-specific considerations [13,14]:

●Procedure-specific factors

•Type of procedure.

•Anticipated duration and complexity of the procedure.

•Need for uncomfortable or unconventional patient positioning.

•Requirement for absence of movement or intermittent apnea.

•Potential for development of hemodynamic instability.

•Need for endotracheal intubation due to planned use of transesophageal echocardiography (TEE).

●Patient-specific factors

•Critical illness or hemodynamic instability. Administration of sedatives or general anesthetic agents may exacerbate hemodynamic instability. Patients receiving vasoactive infusions are at particularly high risk due to inconvenient access to the patient and infusion pumps during imaging.

•Altered level of consciousness with risk for aspiration or unwanted patient movement.

•Inability to cooperate for other reasons (eg, chronic or acute pain, severe anxiety).

•Inability to lie supine due to pain or dyspnea.

•History of difficult airway.

•Obstructive sleep apnea (OSA) or class II obesity resulting in risk for oversedation and inadequate oxygenation and/or ventilation [15-17].

•Tolerance to opioids.

•Patient preferences.

In some cases, the patient must remain immobile during the procedure regardless of the type of anesthesia selected (eg, if very small movements would cause image artifacts). In all cases, the anesthesiologist should be prepared to induce general anesthesia if necessary.

Monitored anesthesia care — If MAC rather than general anesthesia is selected, moderate sedation with a natural airway and spontaneous ventilation are maintained if possible (table 3). In some cases, sedation is provided to supplement a regional or neuraxial anesthetic technique. MAC can be provided using sedative-hypnotics and analgesics through various delivery systems [18].

Maintenance of depth of sedation sufficient to prevent movement may be challenging. A patient's inability to cooperate due to delirium, agitation, or extreme claustrophobia may lead to administration of relatively deep sedation, whereby the patient cannot be easily aroused, but still responds purposefully to painful stimulation, and may require assistance in maintaining a patent airway (table 3). Deep sedation may result in hypoxemia, hypercarbia, or airway compromise, particularly in obese patients or those with OSA (see "Intraoperative management of adults with obstructive sleep apnea"). Interruption of the procedure may be necessary if the anesthesia provider needs immediate access to the patient to manage the airway. In some cases, conversion to general anesthesia becomes necessary. (See "Monitored anesthesia care in adults".)

General anesthesia

●Induction – If a general anesthetic is selected, induction may be accomplished inside the off-site suite or, in some cases, in a holding area just outside the suite.

●Maintenance – Either an inhalation anesthetic technique, total intravenous anesthesia (TIVA), or a combination of these techniques may be employed to maintain general anesthesia [19]. (See "Maintenance of general anesthesia: Overview", section on 'Inhalation anesthetic agents and techniques' and "Maintenance of general anesthesia: Overview", section on 'Intravenous anesthetic agents and techniques'.)

Typically, a relatively light anesthetic depth may be maintained if painful stimuli are minimal. However, for some types of cases, the patient must remain immobile throughout the duration of the imaging and/or the intervention, since even small movements cause artifacts in the image. If coughing or other movement occurs, anesthetic depth is increased. For some patients, it may be necessary to temporarily support blood pressure with a vasopressor (eg, phenylephrine) to maintain depth of anesthesia sufficient to prevent movement. (See "Hemodynamic management during anesthesia in adults", section on 'Selection and dosing of anesthetic agents'.)

The imaging or interventional procedure can be briefly interrupted if it becomes necessary for the anesthesiologist to leave the control room to assure airway patency and/or administer a neuromuscular blocking agent (NMBA) to maintain immobility.

INTERVENTIONAL RADIOLOGY PROCEDURES: SPECIFIC CONSIDERATIONS — Anesthetic considerations and potential complications differ for specific procedures performed in an interventional radiology (IR) suite.

Neurologic procedures — Neurologic IR procedures include emergency and elective intracranial or spine interventions.

Intracranial interventions — Anesthetic management for specific intracranial endovascular interventions is discussed in separate topics:

●Emergency endovascular therapy for acute ischemic stroke [20]. (See "Anesthesia for endovascular therapy for acute ischemic stroke in adults".)

●Endovascular embolization of ruptured or unruptured intracranial aneurysms. (See "Anesthesia for intracranial neurovascular procedures in adults", section on 'Endovascular therapy for intracranial aneurysm'.)

●Endovascular embolization for brain arteriovenous malformations or fistulas, dural arteriovenous fistulas, or lymphatic malformations. (See "Anesthesia for intracranial neurovascular procedures in adults", section on 'Embolization for brain arteriovenous malformation'.)

●Intracranial angioplasty or stenting for large vessel lesions or vasospasm. (See "Anesthesia for intracranial neurovascular procedures in adults", section on 'Anesthesia for vasospasm treatment' and "Intracranial large artery atherosclerosis: Treatment and prognosis".)

Other intracranial procedures include:

●Intracranial venous stenting (pseudotumor cerebri) or thrombectomy (cerebral venous thrombosis, dural sinus stenosis). (See "Idiopathic intracranial hypertension (pseudotumor cerebri): Prognosis and treatment", section on 'Venous sinus stenting' and "Cerebral venous thrombosis: Treatment and prognosis", section on 'Endovascular treatment' and "Septic dural sinus thrombosis".)

●Endovascular intervention for blunt cerebrovascular injury. (See "Blunt cerebrovascular injury: Treatment and outcomes".)

Spinal interventions — For spinal interventional procedures, selection of anesthetic technique is individualized on a case-by-case basis depending on the interventionalist's requirements and patient preferences. Moderate sedation is often sufficient for biopsies or interventional pain procedures.

Many IR procedures for the spine are for cancer-related pathology. Such patients may be at the end of life, with considerations similar to those discussed below for palliative gastrostomy tube placement. (See 'Gastrostomy tube placement' below.)

In rare cases, somatosensory or motor evoked potentials may be monitored during interventions on the spine in the IR suite to prevent neural injury [21]. Anesthetic management for cases requiring such neuromonitoring is discussed separately. (See "Neuromonitoring in surgery and anesthesia".)

Specific spinal interventional procedures include:

●Spine biopsy for impending or complete pathologic fracture in a patient with a solitary bone lesion, with or without a history of cancer. (See "Clinical presentation and evaluation of complete and impending pathologic fractures in patients with metastatic bone disease, multiple myeloma, and lymphoma", section on 'Diagnostic biopsy'.)

●Vertebroplasty, kyphoplasty, or spinal instrumentation for patients with pathologic spine fractures secondary to metastatic disease. General anesthesia is often selected for these procedures because they are performed in the prone position with limited access to the patients' airway, are painful, and require immobility to minimize risk of damage to surrounding structures. However, kyphoplasty can be completed in selected patients with monitored anesthesia care (MAC) and sedation, with administration of an additional intravenous bolus dose of a sedative-hypnotic and/or analgesic agent before painful cement injections.

Additional information regarding these procedures can be found in the following topics:

•(See "Overview of therapeutic approaches for adult patients with bone metastasis from solid tumors", section on 'Vertebroplasty and kyphoplasty'.)

•(See "Treatment and prognosis of neoplastic epidural spinal cord compression", section on 'Role of vertebroplasty, kyphoplasty, and percutaneous spinal instrumentation'.)

•(See "Management of complete and impending pathologic fractures in patients with metastatic bone disease, multiple myeloma, and lymphoma", section on 'Vertebral augmentation procedures'.)

●Radiofrequency ablation (RFA) – RFA may be an alternative to surgical intervention for epidural spinal cord compression related to vertebral metastases in selected patients. (See "Image-guided ablation of skeletal metastases", section on 'Radiofrequency ablation'.)

●Other techniques for treatment of bone lesions – Other palliative or curative treatments for benign or malignant spine lesions that may be performed in the IR suite include cryotherapy, microwave ablation, laser ablation, and high-frequency intensity ultrasound [21]. In some cases, embolization of the arterial supply of a bony lesion may be employed. (See "Image-guided ablation of skeletal metastases", section on 'Techniques'.)

●Neuraxial techniques for chronic or cancer-related pain management

•Implantation of spinal cord neurostimulators – Spinal cord stimulation (ie, dorsal column stimulation) is a neuromodulation technique used to treat neuropathic and sympathetically mediated chronic pain. Electrodes are implanted in the epidural space using a percutaneous or open surgical technique, and a battery is implanted to supply power. Details regarding the procedure are available in other topics. (See "Spinal cord stimulation: Placement and management".)

•Neuraxial infusion – Placement of catheters for continuous infusion of medications into the epidural or intrathecal space for targeted drug delivery is an option occasionally employed for patients with cancer-related pain refractory to systemic pharmacotherapy. (See "Interventional therapies for chronic pain".)

Procedures for hepatic pathology — Patients with significant liver disease may undergo procedures in the IR suite; preoperative evaluation of these patients is discussed in a separate topic. Notably, pharmacokinetics and pharmacodynamics of most anesthetic drugs are altered in patients with significant liver disease [22]. (See "Anesthesia for the patient with liver disease", section on 'Preoperative evaluation and optimization' and "Anesthesia for the patient with liver disease", section on 'Effects of liver disease on anesthetic drug administration'.)

Transjugular intrahepatic portosystemic shunt procedures — Transjugular intrahepatic portosystemic shunt (TIPS) procedures are performed in patients with portal hypertension who have significant hepatic dysfunction and coagulopathy [23,24]. The TIPS procedure involves creating a shunt between the hepatic and portal veins, which decompresses the portal circulation, thereby reducing portal hypertension and the associated risks of bleeding from esophageal varices or ascites formation. Either sedation with MAC or general anesthesia can be used, but the latter is often preferred in patients with hepatic encephalopathy or ascites with associated risk of aspiration, or if a prolonged procedure duration is anticipated. (See "Overview of transjugular intrahepatic portosystemic shunts (TIPS)" and "Anesthesia for the patient with liver disease", section on 'Anesthesia for transhepatic portosystemic shunt'.)

Potential complications of TIPS procedures include vascular injury, dysrhythmias, hemorrhage from catheter insertion, and pneumothorax. (See "Overview of transjugular intrahepatic portosystemic shunts (TIPS)", section on 'Intraprocedure complications'.)

Procedures for treatment of hepatic tumors — Selected procedures to treat hepatic tumors are performed in the IR suite. These include RFA or cryoablation, as well as embolization of the vascular supply to large tumors in selected cases (eg, colorectal liver metastasis, tumors that are difficult to surgically resect, or combined embolization plus surgical resection) [25]. Anesthetic techniques vary according to practice-specific and patient-specific needs; these include local anesthetic infiltration, paravertebral block, thoracic epidural anesthesia, and newer fascial plane blocks (eg, serratus anterior plane, erector spinae plane, quadratus lumborum, and pectoral nerve blocks), as well as general anesthesia [14].

Procedures for gynecological pathology — Several IR procedures involving percutaneous transcatheter embolization are used to manage gynecological pathology. Sedation with MAC is employed for most of these procedures. Examples include:

●Uterine fibroid embolization (see "Uterine fibroids (leiomyomas): Treatment with uterine artery embolization")

●Uterine artery embolization for adenomyosis (see "Uterine adenomyosis", section on 'Uterine artery embolization, as an alternative')

●Uterine artery embolization for arteriovenous malformation (see "Managing an episode of acute uterine bleeding", section on 'Role of uterine artery embolization')

●Uterine artery embolization as emergency treatment for intractable postpartum acute uterine hemorrhage (see "Postpartum hemorrhage: Medical and minimally invasive management", section on 'Consider uterine or hypogastric artery embolization')

●Ovarian vein embolization for pelvic congestion syndrome (see "Vulvovaginal varicosities and pelvic congestion syndrome", section on 'Management of PCS')

Nephrostomy tube placement — Percutaneous nephrolithotomy is the primary treatment for large or multiple kidney stones, and percutaneous nephrostomy tube placement may be performed to treat obstruction between the kidney and the ureter due to pelvic tumors, retroperitoneal fibrosis, or prior injury. Patients may present with acute or chronic renal insufficiency, or with sepsis due to urinary tract infection. (See "Placement and management of indwelling ureteral stents" and "Kidney stones in adults: Surgical management of kidney and ureteral stones", section on 'Percutaneous nephrolithotomy'.)

Sedation with MAC or neuraxial anesthesia (ie, spinal anesthesia, epidural anesthesia, or combined spinal-epidural anesthesia) may be used in many cases, depending on urgency of the procedure, hemodynamic stability, patient preferences, and positioning for the procedure. However, general anesthesia is typically preferred for procedures performed in a prone position [26,27].

Gastrostomy tube placement — Gastrostomy tubes are placed for feeding and/or suctioning of gastrointestinal contents in patients with defects in the mouth, esophagus, or stomach due to congenital lesions, trauma, prior cancer surgery, or neurologic conditions that make swallowing and eating difficult. To facilitate the procedure, the stomach may be inflated after insertion of a nasogastric tube [28]. (See "Gastrostomy tubes: Placement and routine care".)

Choice of anesthetic technique for endoscopic placement of gastrostomy tubes is based in part on the procedure-specific requirements, including expected duration and complexity. Patient-specific factors may also confer unique anesthetic considerations. Examples include:

●Neurologic disorders such as amyotrophic lateral sclerosis. (See "Perioperative care of the surgical patient with neurologic disease".)

●Neuromuscular disorders such as myasthenia gravis. (See "Anesthesia for the patient with myasthenia gravis".)

●Oropharyngeal or gastrointestinal space occupying lesions that have a high risk of regurgitation and aspiration. General anesthesia with rapid sequence induction and endotracheal intubation is typically selected for these patients. (See "Rapid sequence induction and intubation (RSII) for anesthesia".)

If there are no risk factors for aspiration, moderate or deep sedation may be selected. However, the anesthesiologist should be prepared to induce general anesthesia if necessary. (See "Anesthesia for gastrointestinal endoscopy in adults", section on 'Choice of anesthetic technique'.)

In some cases, palliative gastrostomy tube placement is necessary for a patient who may be at the end of their life (see 'Preanesthesia evaluation' above). Examples include:

●End-stage neurologic disorders with inability to swallow due to central nervous system involvement. (See "Gastrostomy tubes: Uses, patient selection, and efficacy in adults", section on 'Patients with neurologic disorders'.)

●Advanced oropharyngeal cancer or distal mechanical gastrointestinal obstruction after radiation or surgical treatments. (See "Palliative care of bowel obstruction in cancer patients", section on 'Enteric tube decompression'.)

Such patients often request conscious sedation rather than general anesthesia to avoid endotracheal intubation. Consultation with the referring neurologist, oncologist, or palliative care specialist is helpful. Guidance for clinical decision-making in these situations can be found in separate topics:

●(See "Informed procedural consent".)

●(See "Advance care planning and advance directives".)

●(See "Ethical issues in palliative care".)

●(See "Legal aspects in palliative and end-of-life care in the United States".)

●(See "Palliative care: Issues in the intensive care unit in adults".)

Vascular procedures — Certain elective vascular procedures such as endovascular aortic repair, or peripheral arterial balloon angioplasty, embolization, or thrombolysis may be performed in an IR suite. The anesthetic technique selected for these procedures may be sedation with MAC, neuraxial, or general anesthesia. Anesthetic management is described in detail in other topics. (See "Anesthesia for endovascular aortic repair" and "Anesthesia for infrainguinal revascularization".)

For some percutaneous mechanical thrombectomy procedures using devices that either fragment or extract intravascular thrombus, general anesthesia is typically necessary [29]. Invasive cardiovascular monitoring and/or transesophageal echocardiography (TEE) may be employed in patients who have risks for development of hemodynamic instability. For centrally located thrombi (eg, inferior vena cava, pulmonary artery, intracardiac location), the procedure is often performed in a hybrid suite in the operating room (OR) area since conversion to an open vascular or cardiac surgical procedure may become necessary [29].

For the following types of elective or semi-elective vascular procedures, sedation with MAC is typically sufficient:

●Vena cava filter placement (see "Placement of vena cava filters and their complications")

●Dialysis catheter placement (see "Central venous catheters for acute and chronic hemodialysis access and their management")

●Management of chronic venous disease (eg, varicose vein, superficial vein insufficiency) (see "Overview of lower extremity chronic venous disease", section on 'Management' and "Approach to treating symptomatic superficial venous insufficiency")

Endovascular management of traumatic injuries — Some traumatic injuries to vascular structures of the abdomen, retroperitoneum, and pelvis are managed as emergencies in the IR suite [30-32]. (See 'Challenges during emergency cases' above and "Abdominal vascular injury" and "Overview of blunt and penetrating thoracic vascular injury in adults".)

In selected patients (eg, those with noncompressible torso hemorrhage following traumatic injury), resuscitative endovascular balloon occlusion of the aorta (REBOA) is a temporizing measure to support vital organ perfusion, decrease the amount of bleeding distal to the occluded site, and provide a window of opportunity for resuscitation and definitive hemorrhage control [33-35] (see "Endovascular methods for aortic control in trauma"). Anesthetic management of REBOA is described in detail separately. (See "Anesthesia for adult trauma patients", section on 'Resuscitative endovascular balloon occlusion of the aorta'.)

Patients with severe pelvic injuries may require pelvic embolization to control bleeding from the pelvic venous plexus. (See "Severe pelvic fracture in the adult trauma patient".)

Conservative rather than surgical management is advocated for most patients with blunt solid organ injuries (eg, kidney, liver, spleen). However, hepatic embolization procedures may be required to control bleeding.

●Hepatic injury (see "Management of blunt and penetrating renal trauma")

●Splenic injury (see "Management of hepatic trauma in adults")

●Kidney injury (see "Management of splenic injury in the adult trauma patient")

TRANSESOPHAGEAL ECHOCARDIOGRAPHY PROCEDURES

General considerations — Indications for diagnostic transesophageal echocardiography (TEE) include identification of cardiac source of embolism, evaluation of valve disease, endocarditis, aortic dissection, and detection of intracardiac thrombus immediately before cardioversion or other electrophysiology (EP) procedures. (See "Transesophageal echocardiography: Indications, complications, and normal views" and "Role of echocardiography in atrial fibrillation", section on 'Transesophageal echocardiography'.)

TEE is considered an aerosol-generating procedure, which poses potential risk for transmission of coronavirus disease 2019 (COVID-19) and other air-borne pathogens. Details regarding management of nonelective TEE examination in patients with suspected or known active COVID-19 infection are discussed separately. (See "Intraoperative transesophageal echocardiography for noncardiac surgery", section on 'Considerations for patients with COVID-19' and "Transesophageal echocardiography: Indications, complications, and normal views", section on 'COVID-19 precautions'.)

Anesthetic choice

●Local anesthesia – Insertion of the TEE probe is the most stimulating portion of the procedure because probe placement elicits upper airway and gag reflexes. We attenuate these reflexes by administering a topical oropharyngeal anesthetic (eg, lidocaine, typically 200 to 400 mg of a 4% solution sprayed into the mouth).

●Monitored anesthesia care (MAC) – In most patients, TEE examination is performed with topical oropharyngeal local anesthesia and mild or moderate nurse-administered sedation under the direction of the echocardiographer [36]. (See "Anesthetic considerations for electrophysiology procedures", section on 'Minimal or moderate nurse-administered sedation'.)

In selected patients (eg, severe anxiety, tolerance to opioids, obesity, a potentially difficult airway, or potential hemodynamic instability), the echocardiographer consults the anesthesia team to provide MAC with or without deeper levels of sedation. The anesthetic goal is for the patient to maintain spontaneous respiration throughout the procedure, without needing additional airway support other than oxygen administration.

•Oxygen administration – We administer oxygen via nasal cannulae. Advanced airway equipment should be immediately available. In patients with severe cardiorespiratory compromise, high-flow nasal cannula oxygen may be administered [37]. For prolonged cases, noninvasive ventilation techniques using masks designed to allow for insertion of an echocardiography probe can be employed to provide ventilatory support [38].

•Administration of anesthetic agents – After topical oropharyngeal local anesthesia, we administer a moderate dose of intravenous (IV) propofol (eg, 20 to 100 mg), then insert the TEE probe. An alternative technique is administration of small bolus doses of IV midazolam 1 to 2 mg, with or without small bolus doses of fentanyl 25 to 100 mcg.

Although the TEE examination is not painful after probe insertion, patients may experience chest pressure during manipulation of the probe, particularly when it is passed through the lower esophageal sphincter for acquisition of transgastric images. Thus, additional small doses of propofol (eg, 20 mg) may be administered as necessary. For prolonged cases, an infusion of propofol (eg, 25 to 75 mcg/kg per minute) is a reasonable alternative to bolus dosing.

●General anesthesia with endotracheal intubation – Rarely, general anesthesia is requested by the echocardiographer (eg, a hypertensive patient with suspected aortic dissection). Endotracheal intubation is usually necessary for airway control due to the presence of the oral TEE probe. Since the TEE examination is typically brief, long-acting anesthetic or neuromuscular blocking agents (NMBAs) are avoided.

POSTANESTHESIA RECOVERY — Care in the postanesthesia period is discussed separately. (See "Overview of post-anesthetic care for adult patients".)

Some interventional radiology (IR), transesophageal echocardiography (TEE), or other "off-site" suite areas have an attached post-anesthesia care unit (PACU). This arrangement eliminates the need for patient transport over long distances or to a different hospital floor, which incurs risk for heavily sedated or critically ill patients. Considerations for transport of patients to a centrally located PACU (or to an intensive care unit) is discussed separately. (See "Transport of surgical patients".)

SUMMARY AND RECOMMENDATIONS

●Anesthetic challenges in remote locations – Challenges for non-operating room anesthesia (NORA) care in interventional radiology (IR) suites and other hospital locations distant from the main operating room (OR) area include (table 1):

•Transport and preparation of anesthesia equipment – In settings with permanent anesthesia equipment, the anesthesia provider must establish familiarity with the anesthesia machine, monitors, medication cart, and oxygen and suction sources in the remote location. In settings without such equipment, anesthesia personnel must transport the anesthesia machine, monitors, and other equipment, as well as anesthetic agents and other medications to the remote location. (See 'Preparation of anesthetic equipment' above.)

•Positioning of equipment – The anesthesia machine, monitors, and medication cart are bulky items that must be positioned in relation to the radiology and other equipment in the suite. After final positioning, the anesthesia provider may not have easy access to the anesthesia machine and monitors or to the patient; however, the room setup should allow the anesthesiologist to view both the patient and the anesthesia equipment via direct observation or a video monitor. (See 'Positioning of anesthesia equipment' above.)

•Interdisciplinary communication – Multidisciplinary team members (eg, radiologists, anesthesiologists, subspecialized nursing personnel) may be unfamiliar with the procedures and techniques planned by each of the other specialists. Planned events including induction of anesthesia, positioning, specific requirements for the imaging procedure, and postprocedure recovery from anesthesia are discussed in a preprocedure briefing. (See 'Need for interdisciplinary communication' above.)

•Management of emergencies

-Ensure ready access to specialized resuscitative equipment, cognitive aids, and prearrange emergency assistance from specialized personnel. For pediatric cases, responding personnel should be subspecialized in pediatric resuscitation. (See 'Complications during elective cases' above.)

-For emergency cases (eg, traumatically injured patients), we request immediate help from anesthesia personnel for delivery of equipment and assistance with ongoing resuscitation including insertion and monitoring of intraarterial and/or central venous catheters. If necessary, the radiologist can assist with emergency placement of intravascular cannulae. (See 'Challenges during emergency cases' above.)

•Radiation risks – In IR, CT, and electrophysiology (EP) suites, the anesthesia provider will likely be exposed to ionizing radiation. Generally, the anesthesiologist should be physically located in an observation room distant from the source of radiation or stand as far away as possible behind a portable shield and wear suitable shielding equipment. Anesthesiologists who are regularly exposed to radiation risks should wear dosimeter badges to monitor cumulative radiation exposure. (See 'Radiation risks' above.)

●Preanesthesia evaluation – The anesthesiologist reviews the pathology for which the procedure is being performed, the interventionalist’s specific requirements for completion of the procedure and patient-related factors that affect choice of anesthetic technique. In some cases, special preparations are necessary for patient-specific issues (eg, patients who are pregnant, receiving palliative care, or have selected severe comorbidities. (See 'Preanesthesia evaluation' above.)

●Monitoring – Standard American Society of Anesthesiologists (ASA) monitoring (eg, electrocardiography [ECG], pulse oximetry [SpO₂], noninvasive blood pressure [NIBP] cuff measurements) are monitored, including continuous capnography to monitor end-tidal carbon dioxide [ETCO₂]), and intermittent airway pressures and volumes during general anesthesia (table 2). (See 'Monitoring' above.)

●Selection of anesthetic technique – Monitored anesthesia care (MAC) with minimal or deep sedation, regional or neuraxial anesthesia, or general anesthesia may be selected depending on procedure-specific and patient-specific considerations. (See 'Selection of anesthetic technique' above.)

•Monitored anesthesia care – We prefer MAC for most patients rather than general anesthesia. Moderate sedation with a natural airway and spontaneous ventilation are maintained if possible. Deep sedation may result in hypoxemia, hypercarbia, or airway compromise necessitating interruption of the scan to manage the airway. Conversion to general anesthesia may be necessary in some cases (table 3).

•General anesthesia – Either an inhalation anesthetic technique, total intravenous anesthesia (TIVA), or a combination of these techniques may be employed to maintain general anesthesia. Typically, a relatively light anesthetic depth may be maintained since there are no painful stimuli. However, the patient must remain immobile throughout the duration of the scan.

●Considerations for specific IR procedures – Specific IR procedures that may require NORA include IR for neurologic procedures (intracranial or spinal interventions), procedures to treat gynecologic or hepatic pathology, placement of a nephrostomy or gastrostomy tube, elective or emergency vascular procedures. (See 'Interventional radiology procedures: Specific considerations' above.)

●Considerations for transesophageal echocardiography (TEE) procedures – Selected patients (eg, severe cardiovascular disease, inability to cooperate) are referred for anesthetic management. We employ topical local anesthesia (eg, 4% lidocaine spray, total dose 200 to 400 mg) sprayed into the mouth to attenuate upper airway and gag reflexes before sedation with MAC. The goal is to maintain spontaneous respiration throughout the procedure, without needing additional airway support other than oxygen administration. Rarely, general anesthesia is necessary. (See 'Transesophageal echocardiography procedures' above.)

●Postanesthesia recovery – Some IR and other "off-site" suite areas have an attached post-anesthesia care unit (PACU), eliminating the need for patient transport over long distances or to a different hospital floor. Transport to a centrally located PACU or intensive care unit is discussed separately. (See "Transport of surgical patients".)