Ambulatory surgery occurs in a variety of settings. Some centers are within a hospital or in a freestanding satellite facility that is either part of or independent from a hospital. The independent facilities are often for-profit and not located in rural or inner-city areas. Some private companies acquire or build ambulatory facilities and then work usually with local surgeons who become the company’s affiliated staff. Physician’s office may also serve procedures (see Chapter 31 Office-based Anesthesia). Freestanding, independent facilities will continue to grow in number and popularity, although some consumers prefer care in units affiliated with hospitals.

A major concern of freestanding ambulatory surgery growth is that the surgery centers may force some hospitals out of business. This issue can be particularly problematic in areas in which population density or median income is low. Hospitals usually are nonprofit and care for patients who both can and cannot pay. Freestanding ambulatory facilities may also be nonprofit but usually do not provide charity care.

Some surgeons may work exclusively in a freestanding facility and not be on the staff of a hospital. A requirement for hospital staff privileges frequently is that a physician provides coverage for the hospital’s emergency department. Hospitals may try to expand emergency department coverage, but are pressured by some specialist surgeons. Some hospitals have lost emergency department coverage for an entire surgical specialty because that surgical specialty works exclusively in a freestanding facility.

Costs are lower for ASCs. Scheduling can be more predictable because the variety of cases is low. Turnaround times are usually also lower. The profits, particularly for freestanding facilities, do not have to subsidize more expensive areas of the hospital, such as ICUs. They also tend to serve only well-insured patients. Medicare also pays ASCs at a lower percent than what they pay hospitals for the same procedure. Medicare can then save money, though the payment system may force some ambulatory facilities to decide whether they accept Medicare patients.

Procedures appropriate for ambulatory surgery are those associated with postoperative care that are easily managed at home and with low rates of postoperative complications that require intensive physician or nursing management. Establishing a low rate of postoperative complication depends on the relative aggressiveness of the facility, surgeon, patient, and payer. For example, procedures that postoperatively result in intense pain may be treated with continuous regional techniques that are continued at home whereas in other settings, these procedures are limited to inpatients.

Scoring systems have been developed to help determine the likelihood of hospital admission after ambulatory surgery. One system is based on patients who were hospitalized after ambulatory surgery¹ (Table 30-1).

Many facilities set a 4-hour limit as a criterion for performing a procedure. Patients undergoing longer procedures should have their operations earlier in the day, primarily because in most freestanding facilities, the anesthesiologist cannot leave until the last patient is discharged. The need for transfusion is also not a contraindication for ambulatory procedures. Some patients undergoing outpatient liposuction, for example, are given autologous blood. Because of blood banking issues, though, ambulatory procedures that require the use of a blood bank are more commonly performed in larger facilities. Freestanding dialysis facilities commonly receive blood shipped from a blood bank located elsewhere and the same can be set up with freestanding ambulatory surgery facilities. The key is to have proper procedures established.

Some have wondered about the safety office-based procedures, following reports of deaths in Florida (see Chapter 31 Office-based Anesthesia). In one series from Florida that reviewed office surgical incidents from January of 2000 to January of 2006 that resulted in death, injury, or hospital transfer, 46 deaths were identified.² Thrombophlebitis was the cause of death in the majority of patients. In a survey of 7,010 patients undergoing abdominal liposuction, the incidence of deep vein thrombosis was 0.04% and that of pulmonary embolus was 0.02%.³ It is hoped that organizations will soon provide better guidelines for stratifying risk and strategies to prevent venous thromboembolism after liposuction surgery.

Infants whose postconceptual age is <46 weeks, or whose actual age is <60 weeks should be monitored for 12 hours after their procedure because they are at risk of developing apnea even without a history of apnea (Fig. 30-1).⁴ Infants older than 46 weeks and <60 weeks without disease should be monitored for 6 hours after their procedures. In one series of 127 premature patients who underwent inguinal hernia surgery, though, none had postoperative apnea.⁵ Some have found that spinal anesthesia without the use of other drugs intraoperatively or postoperatively is not associated with apnea; although in one study of 62 premature and former-premature infants who underwent surgery using spinal anesthesia, postoperative apnea was seen in 5 of
55 premature infants.⁶ Intravenous caffeine, 10 mg/kg, may help prevent apnea in infants, though the use of caffeine in the care of ambulatory patients at risk for apnea has not been studied.

At the other extreme of life, advanced age alone is not a reason to disallow surgery in an ambulatory setting. In a study of 89 patients who were 65 years and older randomized to receive either inpatient or outpatient care before undergoing inguinal hernia repair, all patients who were randomized to receive care as an outpatient were discharged on the day of surgery.⁷ Up to 2 weeks later, outcome was no different between groups. Increasing age, however, does affect the pharmacokinetics of drugs (see Chapter 7 Basic Principles of Clinical Pharmacology). Even short-acting drugs such as midazolam and propofol have decreased clearance in older individuals. In addition, as mentioned above, increased age may be a factor that affects the likelihood of unanticipated admission.

Admission, by itself, is not necessarily bad if it results in a better quality of care or uncovers the need for more extensive surgery. With proper patient selection for ambulatory procedures, which are usually elective, the incidence of readmission should be very low. Most medical problems that older individuals may experience after ambulatory procedures are not related to patient age, but to specific organ dysfunction. For that reason, all individuals, whether young or old, deserve a careful preoperative history and physical examination.

Whatever their age, ambulatory surgery is no longer restricted to patients of American Society of Anesthesiologists (ASA) physical status I or II. Patients of ASA physical status III or IV are appropriate candidates, providing their systemic diseases are medically stable. In a review of ASA III patients who were compared with ASA I or II patients undergoing outpatient surgery, no significant increase in unplanned admissions, unplanned contact with health professionals, and postoperative complications was found.⁸ Certainly, not all life-threatening diseases have been studied as to how appropriate such patients with these diseases might be if they were to undergo ambulatory surgery. Yet, of those patients with such diseases who have been studied, the disease label itself does not seem to preclude an ambulatory surgical procedure.

Patients who are obese represent a special situation. They are not more likely to have adverse outcomes, although they have a higher incidence of obstructive sleep apnea (OSA). In a review of 235 obese patients (body mass index [BMI] >40) who underwent outpatient surgery and were matched with control patients, unplanned admissions did not differ between groups.⁷,⁹ In a study of obstructive sleep apnea in patients undergoing ambulatory surgery, undiagnosed OSA was relatively common, and there was no relationship between OSA and unplanned hospital admission. Patients with OSA, though, had a higher likelihood of difficult intubation, needed more pressors, and needed more oxygen management in the PACU.¹⁰ Some feel that patients who need more narcotics may be at greater risk for apnea and should be observed for a longer period after their procedure. The ASA published practice guidelines for the perioperative management of patients with OSA.¹¹ In those guidelines, the authors state that for patients with OSA, if a procedure is typically performed as an outpatient procedure and local or regional anesthesia is used, the procedure can also be performed as an ambulatory procedure. Yet for patients who are at increased risk for perioperative complications, the procedure should not be performed in a freestanding ambulatory surgery facility. Table 30-2 presents a more complete list of recommended ambulatory procedures for patients with OSA, based on the ASA guidelines.

Patients who undergo ambulatory surgery should have an adult take them home and stay with them afterward to provide care. Before the procedure, the patient should receive information about the procedure itself, where it will be performed, laboratory studies that will be ordered, and dietary restrictions. The patient must understand that he or she will be going home on the day of surgery. The patient, or some responsible person, must ensure all instructions are followed. Once at home, the patient must be able to tolerate the pain from the procedure, assuming adequate pain therapy is provided. The majority of patients are satisfied with early discharge, although a few prefer a longer stay in the facility. Patients for certain procedures such as laparoscopic cholecystectomy or transurethral resection of the prostate should live close to the ambulatory facility because postoperative complications may require their prompt return. “Reasonable” distance and time for the patient to get care if problems arise are not easily defined. This issue must be addressed by each facility and by each patient, and also depends on the type of surgery to be performed.

Each outpatient facility should develop its own method of preoperative screening to be conducted before the day of surgery. The patient may visit the facility, or the staff members may telephone to obtain necessary information about the patient, including a complete medical history of the patient and family, the medications the patient is taking, and the problems
the patient or the patient’s family may have had with previous anesthetics. Screened patients may be less likely to cancel surgery. The screening may uncover the need for transportation to the facility or the need for child care. The process also provides the staff with an opportunity to remind patients of arrival time, suitable attire, and dietary restrictions (e.g., when to stop eating and drinking, no jewelry or makeup). Staff members can determine whether a responsible person is available to escort the patient to and from the facility and care for the patient at home after surgery. The screening is the ideal time for the anesthesiologist to talk to the patient, but if that is not possible, the anesthesiologist may review the screening record to determine whether additional evaluation by other consultants is necessary and whether laboratory tests must be obtained. Patients who do not show up for their clinic appointment may be more likely not to show up for their operation.¹²

Automated history-taking may also prove beneficial during the screening of a patient. Computerized questionnaires or checklists with plastic overlays automate the acquisition of patient histories, flag problem areas, and suggest laboratory tests to be ordered. Such devices can also be used in a surgeon’s office, both to guide the surgeon in the selection of laboratory tests and to serve as a medical summary for the anesthesiologist. Such devices are particularly useful to control the cost of preoperative testing. They enable test ordering based on information obtained from a patient’s responses to health questions, thus eliminating requests for tests that are not warranted by history or physical examination.

The outpatient is not that different from the inpatient undergoing surgery. In both, premedication is useful to control anxiety, postoperative pain, nausea and vomiting, and to reduce the risk of aspiration during induction of anesthesia. Because the outpatient is going home on the day of surgery, the drugs given before anesthesia should not hinder recovery afterward. Most premedicants do not prolong recovery when given in appropriate doses for appropriate indications, although drug effects may be apparent even after discharge.

There are several choices among anesthetic methods: General anesthesia, regional anesthesia, and local anesthesia. Regional and local anesthesia can be used with or without sedation. Except for obstetric cases, for which regional anesthesia may be safer than general anesthesia, all three types are otherwise equally safe. However, even for experienced anesthesiologists, there is a failure rate associated with regional anesthesia.

Certainly, some procedures are possible only with a general anesthetic. For others, the preference of patients, surgeons, or anesthesiologists may determine selection. The cost of sedation is usually less than the cost of a general or regional anesthetic. In a comparison of costs for patients undergoing inguinal hernia surgery in ten hospitals in Sweden, for example, intraoperative and postoperative costs were least in patients who received local anesthesia.²⁹ Those patients who received local anesthesia also spent less time in the OR, had less postoperative pain, and the least problems with urination. The three types of anesthesia, though, are not an option for all operations. In another study that compared groin hernia repair after either general, regional or local infiltration, medical complications were more common after regional versus general anesthesia and urologic complications were more common after regional versus local infiltration.³⁰ Less cost, then, may not always also be accompanied by improved quality. Where spinal anesthesia was compared to general anesthesia for patients undergoing hip or knee replacement procedures, costs for drugs and supplies were less for spinal anesthesia; recovery costs were also less due to less cost for pain management.³¹

Time to recovery may also influence the choice of anesthetic method. In a study of patients undergoing prostate biopsy, discharge after general anesthesia was faster than after spinal anesthesia.³² Conversely, in a study of patients undergoing upper limb trauma surgery, pain in the PACU and time to meet criteria for hospital discharge was less than for patients who underwent
general anesthesia for the procedure.³³ In a meta-analysis of peripheral nerve and central neuraxial blocks compared with general anesthesia, time until discharge from the ambulatory surgery unit was no different for the three groups.³⁴ Interestingly also, postoperative nausea in the central neuraxial block group was not different from the general anesthesia group. In a study of patients undergoing spinal or general anesthesia for knee surgery, recovery times were equivalent, but after spinal anesthesia, postoperative side effects were fewer.³⁵ In a study of stop-flow perfusion, a chemotherapeutic technique, where spinal anesthesia and general anesthesia were compared, anesthesia preparation was 5 minutes longer for spinal anesthesia, though using the study’s standards for PACU admission, only patients receiving general anesthesia needed PACU admission.³⁶ Also, pain and PONV were greater in the general anesthesia group. When applying studies of regional anesthesia to everyday practice, remember that the studies come from centers where the authors are experienced in performing regional anesthesia and that might not be the case in other practices.