Introduction
When the freestanding ambulatory surgery movement was initiated there was a need to establish a strong safety profile and credibility with all involved consumers, i.e., patients, physicians, and third party payers. Consequently, only “healthy” patients were ‘acceptable candidates’ for ambulatory surgery. Today, the sub-specialty of ambulatory anaesthesia has progressed to the total complex care of a broad spectrum of surgical patients undergoing thousands of different procedures under all types of anaesthetics. The 21st century brings a new era of cost- containment to the arena of ambulatory surgery which forces the practitioner of modern ambulatory anaesthesia to reevaluate our practice patterns. This article will provide an update on current controversial issues in adult outpatient anaesthesia, including online preoperative evaluation, patient preparation and selection, laboratory screening, fast tracking and a discussion of a new and exciting class of peri-operative analgesics.

Value- Based Anaesthesia Care: What is it? What Does it Mean to Anaesthesiologists?
The increased interest in cost-containment, limited resources and growing concerns about patient outcomes will require anaesthesiologists to continually assess the cost to benefit ratio of each facet of their anaesthetic practice. It has been suggested that purchasers of health care might seek to obtain “value based care – essentially the best patient outcome achievable at a reasonable cost.” Objective evaluations of each facet of our practice must be performed as an integrated package if health care provider groups are to remain economically viable. For example, excessive concern over drug acquisition costs, to the exclusion of the impact of the drug acquisition costs on clinical outcomes, may be penny-wise but pound-foolish.

The How’s and Why’s of Preoperative Evaluation
The continued growth of outpatient surgery has created new potential role for the anaesthesiologist which seemingly demands skills in addition to “giving a good anaesthetic”. Particularly in the freestanding and office environments, it is often the anaesthesiologist who is most involved in the direct medical care of the patient. We are the physicians who must ensure that the patient is properly screened, evaluated and informed prior to the day of surgery. Indeed the anaesthesiologist/patient relationship which sometimes develops often takes on a primary care quality. Although sometimes difficult to arrange, the preoperative interview and evaluation by a consultant anaesthesiologist (particularly in high risk patients) can be extraordinarily beneficial. In addition to lessening anxiety about the surgery and anaesthesia, in most cases, the anaesthesiologist will be able to identify the potential medical problems in advance, determine the aetiology, and if indicated, initiate appropriate corrective measures. In most facilities, the goal is to resolve preoperative problems well in advance of the day of surgery, thereby minimizing the numbers of both cancellations and complications.

At the present time, there are several commonly used approaches to screening patients for ambulatory surgery. These include: (1) facility visit prior to the day of surgery, (2) office visit prior to the day of surgery, (3) telephone interviews/no visits, (4) review of health survey/no visit, (5) preoperative screening and visit on the morning of the surgery, and (6) computer assisted information gathering. Each system has its own advantages and disadvantages which will be reviewed more thoroughly. Patients who have been adequately screened and prepared pre operatively are much more likely to proceed to surgery in a more cost- efficient manner.

The preoperative patient testing centre at the Thomas Jefferson University Hospital in Philadelphia has recently been transformed to a computerized system; Scheduling and tracking of patients is now done on the Jefferson system for routing, interviewing and tracking – JeffSprint. This system makes liberal use of drop down lists, check boxes and mouse- click interactions. Thus, the use of such technology enables the clinic to process more patients everyday.

At the Cleveland Clinic and its many associated facilities, Dr. Walter Maurer has pioneered the use of the HealthQuest System. This electronic preoperative screening system can be utilized at a variety of sites including hospitals, ambulatory service centres and even surgeons offices. Implementation and widespread use of this system has dramatically improved preoperative screening efficiency and patient satisfaction. This group has presented on cost analysis using the HQ patient assessment programme. Over a 3 year period, total of 50,967 patients utilized their HQ system in the office, resulting in 22,694 patients, who were able to bypass a clinical visit. For those patients meeting HQ “express” criteria, an unneeded step in the preoperative process, was eliminated. The savings generated can be used to offset additional operating expenses.

Should Patients Age or ASA Physical Status Influence Case Selection?
Although the vast majority of individuals scheduled for outpatient surgery are relatively healthy (ASA physical status 1 and 2), practitioners are constantly being pressured to consider “simple outpatient surgery” for patients with significant baseline disease. In the past, many individuals had arbitrarily stated that freestanding ambulatory surgical facilities were severely limited in the type of patients they could anaesthetize, particularly with regard to age and physical status. Recent clinical experience suggests otherwise. In a retrospective study of over 1500 cases of patients anaesthetized for ambulatory surgery, Meridy was unable to demonstrate an age-related effect on the duration of recovery or on the incidence of postoperative complications. Natof concluded that ASA 3 patients whose systemic diseases were well controlled preoperatively were at no higher risk for postoperative complications than ASA 1 or 2 patients. Furthermore, in 1987 the Federated Ambulatory Surgery Association (FASA) published the results of a survey involving over 87,000 patients and concluded that there appeared to be little or no cause and effect relationship existing between pre-existing disease and the incidence of peri-operative complications. In summary, outpatient surgery is no longer restricted to young healthy patients. Geriatric and higher risk (physical status 3 and 4) patients may be considered acceptable candidates for outpatient surgery, if their systemic diseases are well controlled and the patient’s medical condition is optimized preoperatively.

The Inappropriate Patient – Who’s OK and Who’s Not

• Unstable ASA physical status 3 and 4.
• Malignant hyperpyrexia
• Monoamine oxidase inhibitors
• Complex morbid obesity/complex sleep apnoea
• Acute substance abuse
• Psychosocial difficulties.

There are few data to reliably categorize the inappropriate adult surgical outpatient. As anaesthesiologists have become more experienced with the anaesthetic management of the problem surgical outpatient, the list of “inappropriate” patients has dwindled. We must individualize our decision with regard to each patient; with few exceptions, the appropriateness of a case for outpatient surgery is determined by a combination of factors including patient considerations, surgical procedures, anaesthetic technique, and anesthesiologist’s comfort level.

• Unstable ASA physical status 3 and 4: At the present time we are reluctant to proceed with elective ambulatory surgery in a medically unstable patient. Instead, we use our preoperative evaluation clinic to screen these patients, refer them to appropriate medical consultants, and together with the primary care surgeon, establish a plan to proceed with surgery after medical stabilization. Contrary to the original “ground rules” of ambulatory surgery, neither studies involving tens of thousands of patients seem to suggest that neither increasing age nor the presence of stable pre- existing disease after the incidence of postoperative complications in the surgical outpatient.
• Malignant hyperpyrexia: Overnight hospitalization and observation is usually indicated for patients with a history of malignant hyperpyrexia. However, patients who are well educated, have a good understanding of their disease process, and have ready access to medical care may be treated as outpatients by some centres.
• Monoamine oxidase inhibitors: Because of the haemodynamic instability associated with the anaesthetic management of patients currently receiving monoamine oxidase inhibitors, these medications are discontinued at least 2 weeks prior to elective surgery. However, this practice has recently been questioned particularly in light of the resurgence of monoamine oxidase inhibitor use in the general population.
• Complex morbid obesity/complex sleep apnoea: Although patients who have a history of sleep apnoea or who are morbidly obese without systemic disease are acceptable candidates for ambulatory surgery, overnight hospitalization and postoperative observation for morbidly obese surgical patients with pre- existing cardiac, pulmonary, hepatic or renal compromise or those patients with a history of complex sleep apnoea is preferred.
• Acute substance abuse: Because of increased likelihood of acute untoward cardiovascular responses when one administers an anaesthetic to a patient who has recently abused illicit drugs.
• Psychosocial difficulties: Patients who refuse to electively proceed with their surgery on an ambulatory basis cannot be forced to do so. Patients who have received anaesthesia should be discharged in the care of a responsible adult.

What Labs Are Really Needed?
Under the false belief that “shotgun” labs are best for patient and doctor, many ambulatory surgery programmes continue to obtain substantial batteries of preoperative laboratory studies for their patients. However, the majority of tests which are actually ordered and obtained do not contribute beneficially to peri-operative management. Although laboratory tests can help to optimize a patient’s peri-operative condition once a disease is diagnosed, they inherently possess some shortcomings: (1) They frequently fail to uncover pathologic conditions, (2) The abnormalities they sometimes discover do not necessarily improve patient care or outcome, (3) They are quite simply inefficient in screening for diseases which are not identifiable through a careful history and physical examination, (4) Abnormalities which are discovered through laboratory screening are not appropriately followed up and (5) False positives on laboratory screening often lead to increased patient anxiety, increased operating room delays and costs, may lead to more invasive diagnostic tests and therapies, which may actually injure patients.

Many facilities now determine which pre-operative tests are “required” based on the operative feature procedure and the patient’s age, pre-existing medical disease, and medication history. For example, Roizen suggests a bare minimum of pre-operative laboratory screening for healthy patients, but emphasizes that patients with significant baseline disease (hypertension, coronary heart disease, diabetes) will need additional studies (ECG, electrolytes, chest X-ray). However, age at above should not dictate the need for additional studies.

How Well Do We Manage Pain?
The international association for the study of pain has defined the word pain as “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage”. Acute pain is a complex and subjective response and may be produced in a variety of situations, including surgical settings, renal colic, and acute medical conditions. Acute pain, including “surgical” pain, following ambulatory surgery, results in a wide variety of physiologic changes, including the general neuro-endocrine stress response, as well as, secondary effects on respiratory, cardiovascular, gastrointestinal, genitourinary and musculoskeletal system. Inadequate pain relief is believed to lead to significant deleterious outcomes; relief of post surgical pain may in and of itself, play a role in mediating post-operative responses.

As the sub-speciality of ambulatory anaesthesia has expanded to include the total complex care of a broad spectrum of surgical patients, practitioners have been challenged to improve their peri-operative pain management techniques. 77% of patients still experience pain peri-operatively. In outpatients, 80% of patients experienced pain after discharge, with 82% of those patients reporting their pain was moderate, severe or extreme.

Discharge criteria

• Awake, alert, oriented, responsive (Or return to baseline).
• Minimal pain
• No active bleeding
• Vital signs stable (not likely to need pharmacologic intervention).
• Minimal nausea
• No vomiting
• If non depolarizing neuromuscular blocking agent used, patient can perform 5 second head lift.
• Oxygen saturation of 94% on room air (3 mins or longer) or return of oxygen saturation to baseline or higher.

In order to be eligible to bypass phase 1 recovery (PACU), the patient must meet all of the above criteria, and in the judgement of the anaesthesiologist, be capable of transfer to the step down unit, with apt care and facility for patient management at that location.

Summary
Today, there is a continued trend to expand the indications for ambulatory surgery. Because outpatient anaesthesia is a break from our traditional training, we are constantly being confronted with the need for change in our clinical practice patterns. We have recognized that the needs of the surgical outpatient may be very different from the inpatient and are now trying to adapt our practice patterns to meet the psychological and pharmacologic requirements of the compacted peri-operative management, the outpatient receives.

Consultant Anaesthetist, Intensivist and Pain Physician,Bombay Hospital Institute of Health Sciences, Mumbai 400 020.