The editors and publisher would like to thank Dr. Douglas G. Merrill for contributing to this chapter in the previous edition of this work. It has served as the foundation for the current chapter.
Outpatient anesthesia embodies many of the technologic and pharmacologic perioperative advances of the past 200 years. Currently, most surgery is conducted on an outpatient basis; patients arrive from home at a surgical facility, have an interventional procedure or surgery, and return home with their friends and families to heal. The outpatient surgical and anesthetic experience, however, begins well before, and extends well beyond, the day of surgery and anesthesia.
The vision for outpatient anesthesia began 100 years ago when Dr. Ralph Waters opened the first modern ambulatory surgery center (ASC) in downtown Sioux City, Iowa, “the Downtown Anesthesia Clinic.” In the late 1950s and early 1960s, outpatient surgery facilities were opened in Canada and the United Kingdom to relieve waitlists for elective surgery in hospitals. In 1962, Dr. David Cohen and Dr. John Dillon opened an outpatient surgery clinic, which would be a precursor to the modern “surgicenter.” They proposed attention to quality measures, patient evaluation and selection, and availability of equipment with an emphasis on standardizing the patient pathway and flow. They demonstrated significant savings to patients and insurance companies with good outcomes. In 1970 when inpatient surgery became more expensive, Drs. Wallace Reed and John Ford opened the first modern American ASC, the Phoenix Surgicenter, with the primary goal of decreasing the cost of surgery for patients while maintaining quality and safety. These sites embodied the value that surgery centers and office-based surgical practices still provide today: high quality, convenience, and cost savings to patients, their families, and the surgical team. Timeliness, effective operations, and excellent clinical outcomes regarding the patient experience are fundamental to that convenience.
This chapter serves as a primer on the unique aspects of modern outpatient anesthesia practice with an emphasis on optimizing outcomes and the patient experience while modulating costs.
Outpatient Anesthesia is Different
In 1985, when it was founded, the Society for Ambulatory Anesthesia (SAMBA) sought to define the field of outpatient anesthesia. Through promulgating standards of care and a myriad of guidelines, SAMBA shaped clinical care, research, and education. With technologic advances in surgery and pharmacologic advances in anesthesiology, many surgeries performed nationally shifted to the ambulatory setting and with the shift, the practice patterns of the ambulatory anesthesia provider soon evolved. Although not all anesthesia providers are expected to provide anesthesia for complicated cardiac valve replacement surgery, they may be expected to administer a successful ambulatory anesthetic. An ambulatory or outpatient anesthetic is not simply an anesthetic that is followed by a patient discharge home. An outpatient anesthetic procedure respects the patient’s and surgeon’s time as valuable resources and maximizes predictability through preparation and prevention of even the most minor morbidities in the hours to days that follow the procedure. Outpatient anesthesia is multidisciplinary, readily accessible, cost-effective, patient-centered, and at its penultimate, a model for the “Surgical Home” (also see Chapter 51 ).
Outpatient Anesthesia is Patient-Centered
Ambulatory surgery requires a minimally invasive anesthetic with maximal emphasis on patient safety, comfort, and recovery. The challenges inherent to this requirement have led to innovative and highly patient-centered methods by ambulatory groups. To provide the best service, the expectations of the patient and his or her family should be understood. Box 37.1 outlines these expectations. Patient expectations and familial support should be assessed and addressed before performing outpatient anesthesia and surgery to ensure that the facility and its personnel can meet the patient’s expectations. To achieve the goals desired by patients, families, and the medical team, the anesthesia providers and the facility’s leadership should subscribe to specific aims. Key aims for an outpatient care facility are described in Box 37.2 .
Safety during procedure
Relief of pain
Freedom from nausea
Rapid return to normal daily routine
Minimal burden to patient caretakers, which may include family or friends
Maintain a predictable environment through critical case and procedure selectivity
Promote a culture of vigilance and patient safety that exceeds that of the hospital setting
Monitor peer-reviewed literature and track patient outcomes and experience to develop evidence-based “best practices”
Standardize workflow with “best practices” that leverages predictability to create consistently excellent outcomes for patients, families, and surgeons
Defining the Value of Ambulatory Care
Outpatient surgery can be performed in various settings, and is typically defined by a same-day “come and go” experience for patients. The procedures can take place near or far from a hospital, in an office, freestanding ASC, freestanding hospital outpatient department, or a hospital-based outpatient department. The facility ownership can be equally diverse ( Table 37.1 ). In both Canada and the United States, ambulatory surgical facilities have an established safety record. Through accreditation and multidisciplinary oversight, well-established patient safety-related standards of care, careful patient and procedure selection, and a specialized workforce, favorable outcomes in a large volume of procedures are accomplished with a modicum of complications and an extremely small or even rare mortality rate.
|Facility||Potential Ownership Structure|
|Hospital outpatient department||Hospital or investment group, cannot be physician owned as of 2010, PPACA mandate|
|Ambulatory surgery center||Hospital, physician group, nonphysician investors, ownership may preclude referring providers such as primary care physicians to preserve compliance with the Stark antikickback legislation|
|Surgeon, dentist, or proceduralist’s office||Hospital, physician group, nonphysician investors|
Ambulatory surgical care has several economic and social benefits for patients, surgeons, and insurance payers. The outpatient surgical setting offers significant cost reduction with excellent outcomes in patient safety and satisfaction. From 1981 to 2011, outpatient procedures grew almost 10-fold and accounted for 19% to more than 60% of all surgeries performed in the United States. Surgeries take less time at ASCs than at an inpatient facility. From 2008 to 2010, new freestanding ASCs opened primarily in economically advantageous markets with the least amount of competition. Commercial payer rates, case volume, cost control, and specialized billing practices influence ASC profitability.
Enabling successful outcomes requires the careful selection, evaluation, and preparation of patients with regard to comorbid conditions and social structure. Selectivity enables providers to anticipate the likely duration of the intake and preparation process, anesthesia evaluation, surgical period, and recovery. The ideal surgical candidate may differ depending on the practitioners involved, scheduled procedure, and the practice setting. Patient and procedure selection aimed at avoiding unexpected events is undoubtedly the reason that ASCs are historically safe venues. Yet, more must be known about the patient characteristics (e.g., comorbid conditions and baseline pathophysiologic derangements) that occasionally can lead to quality and safety failures.
Many comorbid conditions require intraoperative and postoperative consideration. Failure to recognize comorbid conditions may result in increased cost and, more importantly, perioperative morbidity. Facilities typically implement care pathways to ensure consistent, evidence-based care. No single list of acceptable patients or case types will work for all venues. These conditions should be approached in an organized and meticulous fashion, incorporating the existing guidelines from professional societies to create a personalized patient plan while seeking to minimize complexity and maximize predictability.
Ambulatory anesthesia providers embody a distinct set of skills that, like all subspecialists, set them apart from their peers. An ambulatory anesthesia provider appreciates the value of standardized work, effectively communicates with the team, values the patient’s and surgeon’s time, employs broad but cost-effective multimodal analgesia, and administers minimally invasive short-acting, fast emergence anesthesia for a rapid and safe recovery. The specialization of the team that works in an operating suite is a primary determinant of the duration and predictability of operative room time and postanesthesia care unit (PACU) stay.
Leadership is critical to the well-being of outpatient care facilities. Differences exist between the specific practices of the various outpatient anesthesia venues, yet standardized monitoring of patient safety, crisis preparedness, personnel education, and cost control are required regardless of site and depend on the direction provided by the facility’s leadership team.
ASC and office anesthesia providers typically find their responsibilities expanded to fulfill the role of medical director, helping the site maintain compliance with regulatory and legislative directives. Continued compliance requires awareness of state, payer, and federal regulations for a multitude of issues including, but not limited to, keeping medication records, restrictions on facility size, maintenance of emergency equipment, sterilizing systems, personnel-to-patient ratio, and availability of recovery beds. Because anesthesia providers are often present for the longest periods at ASCs and offices, they typically become advisors to the administrative teams who manage the facility and frequently become the de facto medical director. There are no courses or curricula for becoming a medical director of an ambulatory surgery facility. The ambulatory track at the annual meetings of the American Society of Anesthesiologists (ASA) and the SAMBA offer a modicum of continuing education in medical direction and a network for guidance and mentorship. A highly functioning medical director is essential to the success of the daily workflow of the facility as well as to the patient experience and safety. Maintenance of accreditation is a shared responsibility of the facility spearheaded by the medical director.
Multidisciplinary Leadership and Standardized Care
Unnecessary variation and a hierarchical culture that fosters a lack of transparency and teamwork are often the sources of unsafe, inefficient, and high-cost practices in the delivery of health care. One effective response is for health care delivery teams to integrate published studies and guidelines with analysis of local outcomes. The data should then be developed. Algorithm-driven policies to modulate or eliminate unnecessary variation should be used. The ASC or office is a uniquely suitable location for this work. It is a homogeneous environment in which fewer providers perform a smaller set of procedures when compared to the inpatient operating suite. Patient-care decisions in the most stable clinical environments achieve the best outcomes and best practice.
To achieve maximal predictability, consistent guidelines and directives for management of specific patient comorbid conditions should be agreed upon by surgeons, facility leadership, and anesthesia providers and written into durable policies and procedures for reference. The most effective means to develop standard care plans use multidisciplinary teams of physicians and nurses to assay the literature, visit model peer sites, create protocols with specific exclusion criteria, measure the clinical outcomes of practitioners who do and do not adopt the protocols, and report those outcomes to the entire team. Guidelines of this sort vary by venue and should be reevaluated frequently to keep up with the dynamic landscape of patient care. The expectation should be that providers follow set practice guidelines or care pathways, unless an alternative method induces equal or better results than the published “best practice.” At that time leadership should reassess the currently existing practice guidelines.
The ancillary care staff in the outpatient setting is a specialized workforce that contributes substantively to the achievement of the facility’s goals. Specialized nursing and anesthesia personnel typically are trained and rehearsed in emergency care in the freestanding or office setting because of the facility’s relative isolation. ASC operating room providers are often required by accrediting bodies to complete Advanced Cardiac Life Support (ACLS) and Pediatric Advanced Life Support (PALS) training because these individuals are primary caregivers in an emergency situation, usually for a longer period than is a nurse in the operating room of a tertiary care facility.
Much like patient selection, procedure selection seeks to minimize complexity to ensure a predictable operative course and recovery. A facility’s resources, personnel, and patient population may make complex procedures possible. Among the majority of ambulatory surgical procedures are lens and cataract operations, orthopedic procedures, and laparoscopic cholecystectomy (also see Chapter 29, Chapter 31, Chapter 32 ). Increased complexity should be weighed against the potential for case delays, delayed discharge, unanticipated admission, and their impact on patient satisfaction and facility efficiency. Patients who have surgeries with a duration more than 1 hour and who are ASA physical status III or IV, of advanced age (also see Chapter 35 ), and have a large body mass index (BMI) have an increased risk of unanticipated admission.
Some combinations of elective outpatient procedures increase the risk of venous thromboembolism. Outpatient cholecystectomy has specifically been reported safe and, as a consequence, is frequently performed as an ambulatory procedure. Yet, same-day discharge after appendectomy may be a challenge. Emergency laparoscopic appendectomy may be feasible in an ASC when a predictive scoring system is utilized to select candidates who need less than 12 hours of postoperative observation. However, many patients need their appendectomy performed at hours when the ambulatory center is not open. Hospital admission or observation times can be reduced when patients meet the validated criteria for a truncated observation.
Postoperative complication rates resulting in revisits may also determine procedure selection. Same-day thyroidectomy and parathyroidectomy have good postoperative morbidity and mortality profiles but may require revisits within the first postoperative week for hypocalcemia, bleeding, seroma, or hematoma. Such complications can result in acute postoperative airway compromise, which strongly suggests that these cases be performed in locations where inpatient care can be obtained expeditiously.
Place (Surgical Facility)
Maximizing predictability also influences the site selected for surgery. Location and resources typically foster or preclude procedures of significant complexity. Access to hospital-based care must be considered when nonhospital facilities are selected for the care of sicker patients or more complex procedures. If 98% of patients who have a specific surgery can be discharged home the same day, but 2% require overnight observation, that specific surgery should take place where 23-hour postoperative observation is possible. A hospital transfer, which is a rare event, serves as a quality metric for outpatient surgery. The rate of hospital-based acute care encounters via the emergency department in one series was nearly 30-fold more frequent than hospital transfer. The modern challenge for outpatient anesthesia is to safely incorporate more complex cases into the ambulatory setting.
Historically, ASCs were thought to be a safer location to perform surgery than an office. The reasons given for the supposed discrepancy were the careful attention to case and patient selection as well as the on-site preparation practiced by freestanding ASCs. A 2014 study indicates that office-based anesthesia can be as safe as hospital- and ASC-based procedures. Office accreditation, proper procedure and patient selection, provider credentialing, facility accreditation, patient safety checklists, and implementing professional society guidelines improve safety in office-based surgery.
Dental surgery, plastic surgery, and an ever-widening variety of surgical procedures are now being performed in offices rather than ambulatory surgery facilities or hospitals. The office setting is convenient, private, and cost-efficient. The facility requirements, case selection, and anesthesia techniques for office locations have been well defined. The outcomes of office-based procedures have generally been excellent. A few notably high-profile tragedies after procedures in offices highlight the need for vigilant anesthesia care and oversight, regardless of the site of service. A comparison of risk for anesthesia and surgery in an office setting, ASCs, or hospitals is difficult because reporting mechanisms for all are insufficient. The Institute for Safety in Office-Based Surgery has developed a safety checklist to improve preparedness for office-based procedures. Most remote-site injuries related to anesthesia occur as a result of inadequate monitoring, not errors in patient selection. Factors associated with increased risk in the office setting include the use of unqualified surgical or anesthesia staff, a lack of proper equipment and training for resuscitation and other emergencies, and a lack of access to hospitals for the occasional life-threatening emergency. If these factors are eliminated, office-based anesthesia administered by qualified providers in an accredited facility appears to be equally safe.
Simulation and Drills: Site Preparedness
Site preparation for unanticipated emergency situations must be meticulous. ASC and office personnel should simulate common emergencies to enhance system and provider readiness for such events. A SAMBA-endorsed publication provides in-depth drill scenarios with educational material for outpatient practices to assess and improve on preparedness and responsiveness for common emergencies. Like their real counterparts, simulations and drills can be stressful and should be followed by debriefings that emphasize the potential improvements in system design and teamwork rather than individual failings. Simulations may also afford insight into needed changes in patient and procedure selection and the policies and guidelines that shape them.
The Perioperative Journey of an Ambulatory Surgical Patient
An Itinerary for Success
In the ambulatory setting, the patient experience begins well before arrival at an ASC and lasts long after discharge from the recovery room. The need for predictability in ambulatory surgery necessitates a formalized discrete itinerary. The patient flow schematic depicted in Fig. 37.1 illustrates the patient’s journey from selection through postsurgical follow-up and beyond. The ambulatory schematic may differ from site to site but in general several phases exist. Understanding the phases of care and the goals and challenges associated with each one is essential to delivering high value ambulatory care.
Preoperative Phase: Days to Weeks Before Surgery
Patient, procedure, and site selection take place preliminarily in the surgeon’s office and are congruent with the guidelines, policies, and procedures developed by the medical site’s leadership. The preoperative screening of candidates identifies patient characteristics that jeopardize predictability or create complexity or risk in the intraoperative, postoperative, or postdischarge phases of care (also see Chapter 13 ).
Assessing for Adequate Social Support
The patient screening queries about social support, which includes an escort on the day of surgery, a driver to take the patient home, and a caregiver for postsurgical care and assistance with activities of daily living. On the day of surgery, every patient should have an escort on site or immediately available. A driver to take the patient home also should be immediately available. Some centers require a signed statement by the patient that he or she will have a caregiver for the first night after surgery. The escort is present during patient admission and preparation for surgery. If the patient is not able to obtain an escort, driver, or caregiver the night after surgery, the procedure is not scheduled. These requirements are not popular with a few patients, but early identification of patients who lack these resources reduces patient risk and the potential for case cancellation of surgery on the day of surgery. The only patients who might be released alone are those who received only a small dose of local anesthesia and no other anesthesia-related drugs.
Evaluation and Testing: Before the Day of Surgery
Outpatient centers develop workflows for patient screening to avoid cancellations on the day of surgery and to ensure selection of the optimal care setting. Patients are deemed outpatient surgical candidates by their surgeon, but medical issues relevant to intraoperative care and recovery may preclude this outpatient status. The preliminary clinical history submitted at the time of surgical evaluation drives the initial preoperative evaluation and can be augmented by health assessment forms completed by the patient. Relevant health status can be assessed with a form completed on site for preoperative surgical evaluation. The completed form provides a review of systems, medical history, and identification of social support. The form is then transmitted to the surgery facility’s anesthesia group with the booking for the case. A licensed practitioner from the group (physician, advanced practice nurse, certified registered nurse anesthetist [CRNA], or anesthesiology assistant) reviews the forms and determines whether a follow-up phone call is needed based on surgery type and patient comorbid condition. The status of medical conditions is reviewed and a preliminary anesthesia evaluation is then conducted. The need for further testing or evaluation is decided based on medical society guidelines, facility policies, and the anesthesia provider’s judgment.
Testing should be cost-effective and evidence-based. Preoperative testing is overused in patients undergoing low-risk, ambulatory surgery despite a lack of influence on postoperative outcomes. A systematic review has corroborated these findings in elective, noncardiac surgery as well. Although practice in ASCs and office settings has reduced the cost of care delivery, routine preoperative evaluation for low-risk outpatient surgery remains costly. In 2011, 53% of Medicare beneficiaries undergoing cataract surgery had a preoperative evaluation. The health care costs for this cohort in the month preceding the cataract surgery were $12.4 million more than in the preceding 11 months. A subsequent Cochrane Review found that routine testing beforehand did not increase safety for cataract surgery. Yet not all ambulatory procedures have the favorable risk profile of cataract surgery and its minor anesthetic exposure. Preoperative screening should determine a patient’s eligibility for specific outpatient procedures and the setting in which they are performed.
According to published guidelines there is a shift from routine testing to risk stratification-driven specific testing to modify risk and stabilize an existing medical condition. A 2014 review offers current evidence regarding central topics in risk assessment and management for the ambulatory surgical patient. Successful ambulatory anesthesia groups use screening paradigms according to guidelines and communication with patients before the day of surgery to minimize last-minute cancellations, delayed discharge, unanticipated admission, and patient dissatisfaction. Several important clinical issues that should trigger further discussion before the day of surgery are reviewed here.
Cardiovascular Risk Assessment (Also See Chapter 13 )
The 2014 American College of Cardiology/American Heart Association (ACC/AHA) guidelines offer an algorithm for the perioperative cardiovascular evaluation and care of patients with coronary artery disease who are having noncardiac surgery. Because most ambulatory surgery procedures have infrequent perioperative cardiac complications, the guidelines recommend that a patient demonstrate a functional capacity of at least four metabolic equivalent (MET) values for activities; for example, the ability to asymptomatically ascend two flights of stairs. The risk of major adverse cardiac events depends on the surgical procedure and patient characteristics. The guidelines recommend utilizing one of two risk-calculating methods to determine combined risk before surgery. The surgical risk calculator of the National Surgical Quality Improvement Program or the revised cardiac risk index identifies high-risk patients.
After detailed assessment and risk stratification, ambulatory procedures may be attempted in patients with a risky profile once medical status issues have been properly analyzed and addressed. Several key characteristics are associated with increased risk of perioperative complications ( Table 37.2 ) (also see Chapter 13 ). Patients with the associated characteristics require in-depth evaluation and may not be candidates for ambulatory surgery. According to the guidelines, a preoperative resting 12-lead electrocardiogram (ECG) is performed only for patients with known coronary heart disease, significant arrhythmia, peripheral arterial disease, or cerebrovascular disease having intermediate- or high-risk procedures. Such risk assessment is best performed well before the day of surgery (also see Chapter 13 ).
|Organ System||Symptom or Medical Concern|
|Cardiovascular||New-onset or unstable angina |
Myocardial infarction within 6 months
Newly diagnosed cardiac dysrhythmia
Decompensated heart failure
Severe valvular disease
Drug-eluting stent within 12 months
Bare metal stent within 4 weeks
|Pulmonary||Symptomatic bronchospasm |
Increased work of breathing
Severe obstructive sleep apnea
Hypoxia (decreased oxygen saturation)
|Renal||Unknown or insufficient recent dialysis therapy|
|Endocrine||Symptomatic hypoglycemia |
|Neurologic||Recent cerebrovascular accident or unmanaged transient ischemic attack |
Dementia or delirium
|Hematologic||Insufficient cessation of anticoagulants|
Obstructive Sleep Apnea (Also See Chapter 27 , Chapter 50 )
Obstructive sleep apnea (OSA) influences patient physiology and intraoperative and postoperative care. OSA activates sympathetic neurons and leads to hypertension and cardiovascular abnormalities that can cause morbidity or even death perioperatively. OSA, which is undiagnosed in most patients, increases the potential for cerebrovascular events, myocardial infarction, bleeding, perioperative respiratory events, difficult intubation, and death. This diagnosis is critical to establish before ambulatory surgery.
In an ambulatory surgical cohort, patients with established OSA, regardless of severity or compliance with continuous positive airway pressure (CPAP) therapy, had no unanticipated admissions or delayed discharges, suggesting good patient selection and monitoring. The ability to identify patients with OSA preoperatively may improve outcomes through risk stratification and preparation or through referral to a hospital setting. The ASA and SAMBA have updated separate guidelines on the perioperative management of patients with OSA. Patients can be screened at the surgical evaluation or via telephone with a validated screening tool such as the STOP-BANG questionnaire ( Table 37.3 ). The ASA does not recommend a specific screening tool. A thorough preoperative assessment identifies patients at risk and establishes whether associated comorbid conditions are well managed. A licensed practitioner (physician, registered nurse [RN], CRNA, anesthesiology assistant) should screen patients with known or suspected OSA in a systematic fashion before surgery via telephone at a minimum. The assessment confirms the presence or absence of an OSA diagnosis, compliance with CPAP therapy, the presence of a CPAP machine and well-fitting mask, and control of associated comorbid conditions. The type of surgery, the ability to minimize opioid exposure via local or regional anesthetic techniques, and the facility’s ability to treat the complications associated with undiagnosed or uncontrolled OSA and its comorbid conditions may determine suitability. An inability to provide this heightened level of care should defer management to a hospital setting. Table 37.4 lists the comorbid conditions and perioperative concerns associated with OSA and patient characteristics associated with sleep-disordered breathing.
|Components (each worth 1 point)||Interpretation of Scores|
|S noring |
T iredness during the day
O bserved apnea
P ressure: increased blood pressure
B ody mass index (BMI) > 35 kg/m 2
A ge > 50 years
N eck circumference > 40 cm
G ender = male
|<3 points: Low likelihood of OSA |
3 to 6 points: Adequate positive screen, further testing needed
≥5 points: High likelihood of OSA
|Comorbid Conditions||Disease-Related Potential Complications||Characteristics That May Increase OSA|
Ischemic heart disease
Decreased vitality and social functioning on SF-36 (reduced quality of life)
|Difficult mask ventilation |
Oxygen desaturation and hypoxemia
Exacerbation of cardiac comorbid conditions
Risk of reintubation
Prolonged recovery room stay
Hypoxic brain injury
|Down syndrome |
History of difficult intubation
Enlarged tongue or tonsil size
Diabetes Mellitus (Also See Chapter 29 )
There is no hemoglobin A 1c (HbA 1c ) value that precludes a patient from having outpatient surgery; however, adverse perioperative outcomes are associated with an HbA 1c that is more than 7%. Poor glucose control may indicate the presence of other organ system dysfunction including cardiovascular and renal comorbid conditions, making the specific ambulatory procedure relevant. The underlying principle on the day of surgery is to prevent hypoglycemia while perioperatively maintaining basal physiologic insulin levels. The preoperative degree of baseline blood glucose control, end-organ dysfunction from hyperglycemia, and the current therapy must be known. Such information is obtained before the day of surgery. A SAMBA consensus statement provides practical expertise in perioperative management of the diabetic patient in the ambulatory setting.
Chronic Pain (Also See Chapter 44 )
Patients with chronic pain, opioid dependence, or history of severe uncontrolled postsurgical pain or who are receiving buprenorphine or methadone therapy are best identified well in advance of the day of surgery for proper treatment planning. With pain and nausea as common causes of delayed discharge and unanticipated admission, a formal plan for postoperative pain control and follow-up should be established for patients with potential tolerance or intolerance to pain therapy, or for those patients who are currently under the care of a pain physician (also see Chapter 40, Chapter 44 ).
In the absence of neural blockade, opioid-dependent patients may require a 100% to 200% dose increase in baseline opioids postoperatively. Such “uptitration” may not be within the scope of practice of some surgeons or surgical facilities. For some surgeries or patients, regional anesthesia may not be indicated. Preoperative screening and planning may reduce pain-related unanticipated admission, discharge delays, or emergency department visits. Patients with chronic pain may have little faith preoperatively in their ability to go home immediately after surgery. Such fear or expectation should be identified preoperatively and addressed through treatment planning, patient education, and possible hospital-based care.
Preoperative Phase: Day(s) Before Surgery
Once preoperative assessment, evaluation, and preparation are completed and the results reviewed, the patient’s appointment with the facility is confirmed (also see Chapter 13 ). At that time, information regarding an escort and ride is also verified. A preoperative phone call several days before surgery confirms arrival time, reiterates medication and oral intake instructions, answers patient questions, and reconfirms the availability of the escort, ride, and postoperative caregiver. Within 24 hours of surgery a designated facility employee confirms the information about arrival time and need for an escort and ride. These measures reduce case delay and cancellation as well as the consumption of resources required for caring for an abandoned patient.
The days or weeks preceding the surgery are ample time for preliminary assessment of the patient’s candidacy by the anesthesia group. The anesthesia provider may not be assigned to the case until the day before. Upon assignment, the final preparations commence. Health assessment forms are available the day before surgery for review by the anesthesia provider who will be caring for the patient. Timely review detects omissions or oversights in treatment planning so that additional directives or treatment can be added. Although such last-minute preparation is not ideal, even that is not possible if the chart review is delayed until the following morning.
Preoperative Phase: Day of Surgery
The Anesthesia Preoperative Assessment (Also See Chapter 13 )
The ASA and Center for Medicaid Services (CMS) have determined that a preoperative review of the patient’s medical and social history and a physical examination by an anesthesia provider are necessary. As more complicated procedures and patients are accepted in the outpatient setting, the act of conducting a detailed history cannot be abbreviated. Anesthesia providers frequently uncover significant changes in patient health that can affect postoperative and long-term health. Because physical status correlates with unanticipated admission and delayed discharge, a thorough assessment of the medical status of a patient may affect outcome. A brief motivational interview and counseling by anesthesia providers on preventive health issues, such as smoking cessation, can also be effective with minor time commitment.
When patients present for day surgery not in their usual state of health, the anesthesia provider is faced with the challenging question: should we proceed with surgery for this patient today? The essence of this question is whether a patient’s risk is increased. If not, does the added complexity jeopardize the predictability of the procedure and the anesthetic effects? The anesthesia provider asks this untimely question when patients become acutely ill, when the preoperative preadmission evaluation is incomplete, or when patients are noncompliant with previous recommendations for essential consultation, testing, or therapy. Several clinical conditions significantly impact outcome and are described in Table 37.2 . The decision to proceed with surgery is always an individualized assessment best decided in an evidence-based, multidisciplinary manner.
Acute Pulmonary Conditions
If a patient has been given therapy sufficient to achieve optimal medical condition (e.g., medications have been reviewed by the primary physician and no other therapy is believed to be needed) but is still symptomatic (e.g., wheezing at rest, a bedside forced expiratory time of less than 6 seconds, unable to climb a flight of stairs because of dyspnea) or has pulmonary hypertension, surgery should be performed in the hospital environment where respiratory therapy services are ideal. Complicated pediatric airway surgery is not scheduled for a freestanding center but may be performed in a hospital-based center if pediatric intensivists and respiratory therapists with pediatric expertise are readily accessible (also see Chapter 34 ).
Present or recent acute upper respiratory infection (URI) is, in some instances, sufficient reason for postponing a case because of the potential for respiratory complications perioperatively. Supraglottic edema, stridor, laryngospasm, desaturation, and coughing can occur during general anesthesia in patients with URI, particularly when endotracheal intubation has been performed. Although the use of supraglottic airway devices may be associated with fewer problems in these patients, there is still an opportunity for severely negative outcomes, such as laryngeal edema after use of a supraglottic airway device in a patient with a recent URI. The choice of a particular type of anesthetic or technique, the value of an antisialagogue, or the decision to extubate the trachea while the patient is deeply or lightly anesthetized is not clear.
Elective surgery can proceed in patients with a current or recent mild URI if the procedure can be performed safely without endotracheal intubation, the patient has no other cardiac or pulmonary problems (i.e., congenital heart disease, asthma, or chronic obstructive pulmonary disease [COPD]), and the surgical procedure will not impact the airway. Severe, functionally compromising active, or recent pulmonary symptoms necessitate scrutiny and possible delay in elective surgery if more than a local anesthetic is required. Even then, the patient may best initially seek primary care rather than a procedure that could further limit function or activities of daily living during recovery.
Hypertension (Also See Chapter 40 , Chapter 44 )
Patients with hypertension requiring medication who undergo surgery have as much as a 50% more frequent risk of adverse cardiovascular problems in the first 30 days after a procedure. Although angiotensin-converting enzyme (ACE) inhibitors improve hypertension, they may be associated with profound hypotension after induction of general anesthesia. Others have questioned this conclusion. For patients who experience postinduction of anesthesia hypotension, postoperative morbidity and mortality rates increase. The decision to omit antihypertensive drugs preoperatively may increase arterial blood pressure even in a short 24-hour period. Although sedation and general anesthesia can decrease arterial blood pressure, the neurohumoral response to surgical stimuli can be profound, resulting in postoperative lability and difficult-to-treat hypertension in an at-risk population.
If new-onset angina, chronic unstable angina, new cardiac arrhythmia, signs of decompensated congestive heart failure, or recent angioplasty or percutaneous coronary stenting are identified, elective ambulatory surgery is best deferred. No set arterial blood pressure reading calls for cancellation of surgery, but severe preoperative hypertension should trigger a multidisciplinary discussion. The patient’s baseline arterial blood pressure range is a helpful reference for intraoperative management and for deciding whether a surgery should be delayed. If there are symptoms of hypertensive emergency, the ambulatory procedure is rescheduled, and the patient is transferred to acute care.
The Difficult Airway (Also See Chapter 16 )
The “difficult” airway presents a serious challenge in the ambulatory setting. A history of difficult airway should be identified well before the day of surgery through preoperative communication with the patient or review of the health questionnaire. On the day of surgery, a preoperative airway assessment is requisite for reduction of risk. A facility should be prepared for comprehensive airway management for every case. The occult lingual tonsil is defined by its unanticipated nature. For this reason and many others, the equipment required for fully employing the ASA’s difficult airway algorithm should be immediately available and regularly checked for functionality. If regional or neuraxial anesthesia is selected for the patient with a known difficult airway, the contingency for inadequate anesthesia should be discussed preoperatively with the patient and surgeon to ensure all parties appreciate the risks “a touch of sedation” could carry. Endotracheal intubation with the patient awake (i.e., may include a small dose of preoperative medication) may be the safest option despite its perceived delay in workflow.
Pregnancy Testing (Also See Chapter 33 , Chapter 34 )
Some facilities require pregnancy tests for all women of childbearing age, and others offer it only to those women who say they may be pregnant. In one study, mandating that all women undergo pregnancy testing resulted in a cost of over $3000 per positive test, a particularly troubling price in view of an unknown level of benefit. A separate study found that the cost per positive result was $1,005.32 with an unknown benefit of not performing elective surgery on a pregnant woman. Some providers screen patients during preoperative evaluation: “Is there any chance you could be pregnant today?” A “yes” response triggers a test, and a “no” response triggers a statement of confirmation and further counseling: “If there is any chance, we should confirm to make sure we do not unknowingly expose a developing fetus to anesthesia.”
Preoperative Medications (Also See Chapter 13 )
Anxious patients may benefit from a variety of nonpharmacologic techniques for anxiolysis including aromatherapy or listening to music of their choice. Administration of short-acting benzodiazepines or 1200 mg of gabapentin may also improve the anxious or catastrophizing patient’s perioperative experience. Administration of acetaminophen, gabapentin, or pregabalin, and nonsteroidal antiinflammatory drugs (NSAIDs) during the preoperative period initiates preventive analgesia so that serum concentrations are therapeutic before surgical stimuli, potentially reducing secondary hyperalgesia, postoperative opioid requirements, and opioid-related side effects. Preoperative administration of dexamethasone also may improve the patient’s emotional state, physical state, and pain dimensions postoperatively. Postoperative nausea and vomiting (PONV) in the high-risk patient can be mitigated preoperatively with transdermal scopolamine (also see Chapter 39 ). A scopolamine patch applied before transfer to the operating room can be as effective as droperidol or ondansetron in prevention of PONV in adults.
Intraoperative Phase: Anesthesia Techniques
The overall goals of outpatient anesthesia today are unchanged from those espoused many decades ago by Drs. Ralph Waters, Wallace Reed, and John Ford: convenience, small cost, patient safety and care in alignment with the patient’s and surgeon’s goals. Accordingly, the techniques of anesthesia should be chosen for safety and to diminish or eliminate pain, nausea and vomiting, and prolonged cognitive impairment postoperatively. Anesthetic techniques are selected to enable timely recovery. Efficiency, however, should not put patients at risk or jeopardize their comfort or satisfaction. For example, with remifentanil recovery is reliable and rapid, but the risk of hyperalgesia makes it unsuitable for patients having painful surgery or a history of chronic pain. Table 37.5 lists the benefits and adverse effects of various anesthesia types.
|Anesthesia Type||Benefits||Adverse Effects|
|General inhalational||Neuromuscular blockade and intraperitoneal procedures |
Maximal intraoperative airway control when performed with intubation
|PONV, PDNV |
Residual neuromuscular blockade
|General intravenous||Less PONV with propofol |
Neuromuscular blockade and intraperitoneal procedures
Maximal intraoperative airway control with intubation
|Airway injury |
Residual neuromuscular blockade
|Regional||Prolonged postoperative analgesia |
Less risk of airway injury
Reduced exposure to anesthesia
|Local anesthetic systemic toxicity |
Peripheral nerve injury
Spinal headache with neuraxial blockade
Recall of operation and the associated stress
|Monitored anesthesia care (MAC)||Less exposure to anesthetic doses |
Low incidence of sore throat
|Minimal airway control |
Patient dissatisfaction from unexpected recall
Operating room fires with an open system
The anesthetic selection of sedation, general anesthesia, or regional anesthesia depends on several factors: patient characteristics, expectations and positioning, surgical anatomy and technique, surgeon preference, anesthesia provider preference, and risk-reducing or efficiency-driven policies or facility guidelines (also see Chapter 14 ). Although no anesthetic technique is best for all patients, standardizing care may improve outcomes. Treatment pathways require patient education, patient selection, and potentially, various detours in the pathway for individualized care within the standardization. Presence of psychological concerns, need for a language translator, or other patient comorbid conditions may exclude a patient from the typically selected pathway. Ethically, a fine line exists between preserving outpatient center efficiency and impeding access to care. Such deviation from the “typical” pathway should be identified in advance and accounted for in the day’s schedule or the overall planned utilization of personnel and operating rooms.
Monitored anesthesia care (MAC), a term of anesthesia billing, describes sedation by an anesthesia provider. Titrated sedation and continuous monitoring often transition the patient in and out of general anesthesia, as required by changes in patient or surgical conditions. Only providers with anesthesia privileges should administer this technique. Thus sedation/general anesthesia by an anesthesia provider or MAC differs from other light sedation techniques used by nonanesthesia personnel.
Deep sedation (i.e., in between light sedation and general anesthesia) is chosen when general or regional anesthesia is considered too invasive or prolonged for the procedure or patient. The potential for catastrophic outcomes with deep sedation may be equal to or more than that associated with general anesthesia, with particular risks for oversedation and operating room fires. Vigilance and monitoring are critical during deep sedation because of the possibility of hypoventilation and hypoxemia. When choosing deep sedation or general anesthesia, the possible need for oxygen supplementation has to be considered. If the procedure will be so uncomfortable that the patient must be predominantly unresponsive, increased levels of supplemental oxygen may be required. When combined with electrocautery and surgery proximate to the airway, deep sedation without a secured airway may carry the risk of combustion from accumulated oxygen under the surgical drapes. General anesthesia in a closed system allows for safer supplemental oxygen delivery. A history of OSA, uncontrolled gastroesophageal reflux disease, or difficult endotracheal intubation or ventilation may create challenges or conflicts in patient safety if deeper planes of anesthesia are anticipated during deep sedation.
Regional Anesthesia (Also See Chapter 17 , Chapter 18 )
Regional anesthesia—alone or in conjunction with general anesthesia or sedation—may benefit patients and the facility. The modern ambulatory anesthesia provider is an expert in regional anesthesia who modifies tried and true techniques while learning and applying new techniques as they are discovered. Performing regional nerve blocks in a preoperative area for patients undergoing orthopedic procedures decreases overall anesthesia time without increasing turnover time, when compared to general anesthesia. PACU discharge time can be shortened and the immediate postoperative period made more pleasant for the patient. Between 1994 and 2006 the use of peripheral nerve blocks during ambulatory ankle arthroscopy procedures increased from 6% to 26%, reflecting increased utilization by practitioners. The use of regional catheters, in the presence of safe postdischarge conditions, can reduce pain for days after surgery while improving rehabilitation.
Regional anesthesia techniques have revolutionized hernia and breast surgery. Paravertebral regional block decreases opioid exposure, PONV, urinary retention, and pain scores as compared to general or neuraxial anesthetics. Multilevel paravertebral blocks combined with total intravenous anesthesia for breast tumor resection were reliable and improved postoperative analgesia, enhanced quality of recovery, and expedited PACU discharge compared with inhaled anesthetics or opioid-based general anesthesia. Paravertebral block for patients undergoing mastectomy may decrease the incidence of chronic postsurgical chest wall pain and tumor recurrence or metastasis. The serratus anterior plane block and pectoral nerve blocks (pecs I and II) are novel interfascial plane blocks for breast surgery analgesia.
Central Neuraxial Anesthesia (Also See Chapter 17 )
Neuraxial blockade, with or without sedation, has been reported to reduce the incidence of PONV and pain after lower extremity, gynecologic, and abdominal surgery and for patients with chronic respiratory disease. A short-duration “speed spinal” provides substantial value in the ambulatory setting. Spinal doses of lidocaine, mepivacaine, and 2-chloroprocaine provide superb anesthesia for shorter procedures such as knee arthroscopy and inguinal hernia repair. Low-dose spinal bupivacaine (e.g., 4 mg with 20 μg fentanyl) is effective, quick-acting, and rapidly resolving for transurethral procedures in elderly males, without delaying discharge. For outpatient knee arthroscopy, 7.5 mg of 0.5% hyperbaric ropivacaine provides sufficient anesthesia, but with a duration of up to 2.5 hours and a time to discharge of up to 3.5 hours, much longer than with 2-chloroprocaine.
The natural airway creates a potential for risk for some patient-procedure combinations, especially those involving surgery in the airway. The decision to provide general anesthesia with or without endotracheal intubation should be determined by patient and procedure-related risk factors. General anesthesia carries the potential for increased risk of PONV, postdischarge nausea and vomiting (PDNV), airway injury, postoperative hypothermia, postoperative cognitive dysfunction, and delayed discharge when compared to deep sedation or regional anesthesia. General anesthesia may be necessary, however, for procedures that require neuromuscular blockade or peritoneal insufflation. Some patients may refuse regional anesthesia or have conditions that contraindicate it, thus necessitating a general anesthetic.
General anesthesia can be accomplished through total intravenous techniques, combined maintenance with volatile anesthesia and intravenous drugs, or solely with volatile anesthetics. Nitrous oxide may be an adjunct to general anesthesia. Limiting duration of nitrous oxide exposure has been shown to reduce the risk of PONV. Infrequent perioperative morbidity is possible with total intravenous anesthesia or volatile anesthesia. Low-dose propofol infusions, multimodal analgesia, and antiemetic methods further reduce the postoperative risk for nausea and vomiting after general anesthesia. The literature supports several principles for anesthetic selection described in Box 37.3 .