Preoperative Assessment for Specific Locations

17.1 Non-Operating Room Anesthesia

Yasmeen Beg

As technologies continue to emerge, anesthesiologists increasingly are asked to provide anesthesia outside of the traditional operating room setting. Many aging patients undergo noninvasive procedures before or in lieu of surgical treatments. Often, these patients are “too sick for the operating room” and therefore scheduled for nonsurgical approaches. These patients may be unstable and not medically optimized. Consequently, even a simple outpatient procedure can be risky.

Patients in nonoperating room anesthesia (NORA) locations are often medically challenging with complex comorbidities. The anesthesiologist may be asked to anesthetize a patient in a less than ideal state of health on an urgent or semi-urgent basis. A patient on DAPT with a recent coronary stent with significant gastrointestinal (GI) bleeding is an example.

Preoperative assessment for NORA patients can be difficult. Proceduralists may have little knowledge of the patient’s medical history. Often, patients are referred to tertiary care centers for NORA procedures and their routine care is elsewhere. Gathering medical and surgical histories, records and test results can be logistically complicated. Patients may travel long distances and therefore be unwilling or unable to be seen in a preoperative clinic visit before their procedure. Despite these constraints, care of patients follows the same principles as for the operating room (1). The American Society of Anesthesiologists (ASA) Guidelines for Preanesthesia Evaluation (2) indicate that minimum requirements are:

Patient interview including review of medical, surgical, anesthetic, and medication history as well as a physical examination
Review of relevant diagnostic information/laboratory tests
ASA status assignment
Formulation of anesthetic plans and presentation of these to the patient

Ahead of time, if possible, a chart review of NORA patients may avoid costly and frustrating delays or cancellations. Phone screens or in-person assessment may have added value. If a patient has numerous comorbidities, or inadequate primary care, evaluation in a preoperative clinic has advantages (3). Preprocedural testing is determined by patient history, comorbidities, and the planned procedure (4). NORA procedures do not require additional testing in and of themselves. A thorough understanding of both the procedure and the comorbidities of the patient are essential to appropriately plan care.

Each NORA site has unique challenges and perils. However, some commonalities exist in providing anesthesia away from the operating room. When evaluating a patient for a NORA procedure, it is important to be aware of the challenges:

An anesthesia machine may not be standard in the procedure suite
Operating room equipment and personnel support are not immediately available
Emergency equipment may be limited
Medications may not be readily available
Limited information about patients’ medical and anesthetic history
Expectations of short emergence times, quick procedures
Recovery of patients by nurses unfamiliar with recovering postanesthesia patients
Lengthier travel time and distance to recovery area
Quick turnovers between cases
Competing goals of efficiency and patient safety
Radiation exposure to patients and staff
Proceduralists’ unfamiliarity with anesthesia and potential complications (e.g., loss of airway)
Lack of knowledge of fasting guidelines for anesthesia
Inadequate or incomplete medication and NPO instructions
Procedure bed limits for larger weight patients
Beds with limited mobility (e.g., lack of Trendelenburg option)
Unique positioning (e.g., prone)
Occult or overt bleeding and transfusion needs

Patients with extreme anxiety, chronic pain, claustrophobia, significant ascites, obesity or obstructive sleep apnea, may not tolerate lying on a flat, firm table for prolonged periods. Obesity and patient movement interfere with imaging and procedures. The patient must remain still during critical portions of many procedures. Deeper sedation or general anesthesia may be required. Providing a general anesthetic can be time consuming and inefficient in an unprepared NORA setting.

GASTROINTESTINAL PROCEDURES IN THE ENDOSCOPY SUITE

Over the past few decades the number of endoscopic GI procedures has steadily increased (5). Routine screening colonoscopies to complex endoscopic submucosal dissections were historically done with moderate sedation. However, moderate sedation is often inadequate for patients with complex medical histories, or healthy patients having complex procedures.

Endoscopic procedures can be diagnostic or therapeutic, often with the patient in the prone position. For many endoscopic procedures, but especially for endoscopic retrograde cholangiopancreatography (ERCP) it is essential that the patient is immobile. Even with “sedation” bispectral index scores of patients undergoing GI procedures have been found to be in the general anesthesia range (6).

Endoscopists often utilize carbon dioxide to insufflate the GI tract. If a sedated patient is undergoing a prolonged procedure, ventilation may be inadequate in light of the additional carbon dioxide, especially with pre-existing pulmonary compromise. A general anesthetic may be required. Increasingly, endoscopists are performing more complicated and lengthy procedures in their endoscopy suites which may also
necessitate general anesthetics. Endoscopic mucosal resections are often used for staging and treatment of superficial neoplasms of the GI tract (7). In addition to extraluminal biopsies, other advanced extraluminal techniques can be carried out endoscopically. Pancreatic necroscectomies involve removal of necrotic tissue as a treatment for pancreatic abscesses and necrosis. Natural orifice transluminal endoscopic surgery (NOTES) may be increasingly used in the future for cholecystectomies and appendectomies (8).

INTERVENTIONAL PULMONARY PROCEDURES

Patients undergoing bronchoscopy are usually high-risk patients and many procedures requiring anesthesia are more complex than simple bronchoscopy including:

Endobronchial biopsy, laser treatment, cauterization, cryotherapy
Endobronchial stenting
Balloon dilation
Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA)
Electromagnetic navigation bronchoscopy (ENB)
Fiducial marker implantation

An EBUS procedure utilizes ultrasound to visualize the bronchi, mediastinal lymph nodes, and peribronchial anatomy. Computed tomography data are used to create a virtual lung reconstruction with sophisticated computer software in ENB. This allows the bronchoscopist to be guided to the appropriate location. Fiducial markers can be placed via bronchoscopy or ENB before stereotactic radiosurgery (9).

BILIARY AND HEPATIC INTERVENTIONS

Biliary and hepatic interventions include transhepatic cholangiography, percutaneous transhepatic biliary drainage, liver biopsy, portal vein embolization (PVE), and creation of transjugular intrahepatic portosystemic shunt (TIPS). These procedures are among the most challenging performed outside of the operating room. These patients are usually complex with significant compromise. Patients can present with jaundice, cholangitis, or biliary leaks. Contraindications for these procedures include a bleeding diathesis, inability to tolerate contrast, large AVMs, significant ascites, or hydatid disease.

TIPS procedures are often used as a bridge to liver transplantation. During a TIPS procedure, a long vascular sheath is inserted via transjugular access (10). These procedures can be lengthy, stimulating, and usually require a general anesthetic. It is prudent to have blood available for these procedures because these patients are often coagulopathic and there is potential for significant blood loss.

ELECTROCONVULSIVE SHOCK THERAPY

Treatment of major depression and other psychiatric disorders may involve electroconvulsive shock therapy (ECT). ECT-induced seizures activate both the sympathetic and parasympathetic nervous systems (11). Bradycardia and hypotension followed by increased cardiac output, tachycardia and hypertension related to a catecholamine
surge ordinarily resolve a few minutes after seizure termination. Patients with cardiovascular or cerebrovascular disease may be at risk of complications, though ECT treatments have a strong safety record.

Initiation of, or increases in, beta-blocker dose may decrease seizure duration and the efficacy of ECT (12). ECT should be postponed in patients who have had a myocardial infarction within 6 weeks (12). Patients who have rate-controlled atrial fibrillation may proceed with ECT. Therapeutic anticoagulation is recommended in these patients as occasionally ECT may result in conversion to normal sinus rhythm (13). Pacemakers and implantable cardioverter defibrillators (ICDs) are not a contraindication to ECT. However, since ECT can cause transient electrocardiographic changes (increased P-wave amplitude, alterations in QRS morphology, ST/T-wave abnormalities) devices with tachyarrhythmia therapies should have them disabled during ECT. For patients who are pacemaker dependent, it may be advisable to have their pacemaker placed in an asynchronous mode prior to ECT (14,15).

Patients with a history of ischemic or hemorrhagic stroke may proceed with ECT as long as their stroke occurred greater than 30 days previously. Patients with known vascular lesions or aneurysms require a neurosurgical consultation before ECT. In both situations, tight blood pressure control is required (16). In patients with a history of chronic obstructive pulmonary disease, asthma, heart failure, diabetes mellitus, or renal failure it is generally safe to proceed with ECT if the patient is medically optimized and at their baseline.

MAGNETIC RESONANCE IMAGING

Patients requiring an anesthetic for their magnetic resonance imaging (MRI) procedure are a unique subset of patients. Many of these patients have anxiety and are claustrophobic. They are unable to lie still without sedation, even for a diagnostic MRI. Some patients require a general anesthetic for these tests. The requesting physician is not present for the test and often the anesthesiologist, whom the patient usually meets a few minutes prior to the procedure, is the only physician involved in their care. If assessment of a medically complex patient is left to minutes before their procedure, one can see the potential for delays and cancellations. In addition, there is also a need to have procedures in place to ensure that these patients are also given appropriate NPO as well as medication instructions prior to their arrival.

As the MRI scanner utilizes ionizing magnetic fields and radio waves to create images, one must also ensure that patients, and any implanted devices, are screened for MRI compatibility. In general, patients with pacemakers, ICDs, cochlear implants, pumps, nerve stimulators, aneurysmal clips, or other metal fragments should not be scanned as these objects are subject to heating and movement. It is possible for patients with nonferromagnetic materials such as orthopedic implants, staples, vascular clips, and heart valves to undergo MRI scanning (17).

OTHER NORA-RELATED CONCERNS

Contrast Material

Imaging-guided interventions often require that contrast be administered. Contrastrelated reactions can be dose or concentration dependent and occur in 5% to 8% of
patients. Anaphylactoid reactions are unrelated to administered dose or concentration (18). Reactions can include laryngeal edema, bronchospasm, pulmonary edema, hypotension, and respiratory arrest or seizures. Pretreatment with steroids and diphenhydramine in patients with a history of contrast reactions is recommended. Patients with renal insufficiency are at risk for contrast-induced nephropathy. Pre- and posttreatment with N-acetyl cysteine and hydration is recommended for these patients.

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