Patient screening and evaluation

For patients to safely undergo invasive procedures in a nonhospital environment, underlying medical conditions must be identified, evaluated, and stabilized prior to the scheduled procedure. There are no contraindications for patients with significant but stable underlying disease (i.e., American Society of Anesthesiologists, [ASA] physical status categories 3 and 4) to undergo an invasive procedure or operation in an ambulatory setting if the procedure is unlikely to exacerbate the underlying condition or conditions. In 2002, the ASA issued a practice advisory indicating that preoperative testing, particularly laboratory studies, does not significantly improve the preoperative preparation nor significantly alter perioperative management decisions unless indicated by symptoms, clinical findings, or preexisting conditions that warrant evaluation. There is no evidence that perioperative adverse outcomes are influenced when preoperative evaluations are eliminated in healthy or medically stable patients.

A preoperative telephone interview with the patient can often determine the presence and stability of significant underlying diseases (e.g., angina, chronic obstructive pulmonary disease) or special anesthetic concerns (e.g., latex allergy, malignant hyperthermia, obstructive sleep apnea [OSA], a history of difficult intubations) meriting further preoperative evaluation or scheduling considerations. If the intended procedure could impact the stability of a patient’s underlying condition or conditions, a more extensive evaluation can and should be performed before the day of surgery. The telephone interview also provides an opportunity for confirming with the patient the arrival time, place, and directions, as well as a review of preoperative fasting recommendations. This simple intervention reduces day-of-surgery delays and cancellations.

Preoperative fasting is a common issue that must be addressed in any setting in which sedation or anesthesia is anticipated because it influences practice efficiency. The ASA recommends the interval between ingestion and sedation or anesthesia be 2 h for clear fluids, 4 h for breast milk, and 6 h for nonhuman milk and solid food. In most circumstances, preoperative overnight fasting of both food and water has been abandoned prior to elective surgical procedures. Ingestion of clear fluids up until 2 h prior to receiving sedation or anesthesia in patients without risk for aspiration of gastric contents (e.g., no gastroesophageal reflux disease, bowel obstruction) improves patient comfort while preventing dehydration.

OSA is a common diagnosis (9% of middle-aged women, 24% of middle-aged men) of such importance to anesthesia practice that the ASA issued a practice guideline addressing this condition. At this time, there is insufficient evidence to recommend one particular anesthetic technique over another. However, OSA is negatively impacted by the use of intravenously administered sedative and hypnotic agents, as well as inhaled anesthetic agents. Postprocedure recovery and respiratory monitoring warrant significantly longer observation periods in both the inpatient and outpatient settings. The ASA guidelines recommend that, compared with patients without OSA, those with OSA be monitored for 7 h after the last episode of airway obstruction or hypoxemia while breathing room air and for 3 h longer on room air before being discharged to home. These guidelines functionally result in patients with OSA being admitted for overnight or 23-h observation in most cases of untreated OSA or for patients who are noncompliant with recommended continuous positive airway pressure therapy for OSA, as prescribed by the patient’s treating physician. The presence of OSA should not automatically preclude a particular patient from being considered for an ambulatory procedure. However, consideration must be made for the potential implications for airway management and postoperative monitoring for even the most routine procedural interventions.

Anesthetic techniques for ambulatory procedures

Surgical or invasive procedures performed in the ambulatory surgical setting might be prolonged but should not expose the patient to a risk for significant fluid shifts, significant postoperative discomfort, or a need for hospitalization. Similar to nearly any other surgical practice, local anesthesia, monitored anesthetic care, regional anesthesia, and general anesthesia are all reasonable approaches to patient management for ambulatory operations or other outpatient invasive procedures. Local anesthesia infrequently requires the participation of an anesthesia provider. Conscious Sedation is increasingly performed by “sedation nurses” who lack extensive anesthesia training. In circumstances in which a non–anesthesia-trained nurse (or other provider) is administering sedative agents, the potential for achieving a level of sedation that is indistinguishable from monitored anesthesia care or from a general anesthetic is quite possible. As a result, to ensure that sedation provided by individuals other than anesthesiologists, nurse anesthetists, and anesthesia assistants is conducted in a manner that affords prompt recognition and intervention of the deeply sedated or anesthetized patient, the ASA recently released a guideline for practices in which individuals other than anesthesia provider’s deliver sedation. This guideline has been adopted by the Joint Commission and is followed by facilities seeking accreditation from the Joint Commission.

Regional anesthesia offers many benefits for procedures performed in ambulatory surgical centers. This anesthetic approach affords profound analgesia and anesthesia with a lower incidence of PONV, drowsiness, and pain than do general anesthetics. Peripheral nerve blocks (PNBs), however, are infrequently performed in ambulatory surgical centers. Common impediments for utilizing PNBs relate to the additional time necessary to perform the block, delayed onset time, variability of obtaining surgical anesthesia, and the lack of obvious benefit of PNB versus general anesthesia on outcomes beyond 24 h. The introduction and increasing application of ultrasound technologies to facilitate PNB placement and reliability is likely to influence PNB utilization in ambulatory settings even though patient outcomes may not be significantly influenced.

General anesthesia is the most common mode of anesthesia for ambulatory surgical procedures. However, PONV is increased after general anesthesia, compared with after regional anesthesia or PNB, occurring in nearly 30% of patients. Propofol is the anesthesia induction agent of choice because of its low incidence of associated PONV and rapid emergence. Sevoflurane and desflurane have low blood and fat solubilities, allowing more rapid patient awakening, compared with isoflurane or propofol infusions. A multimodal approach for perioperative analgesia attempts to reduce opioid-related somnolence and PONV. Fentanyl is the most commonly administered opioid in ambulatory surgery; remifentanil has a more rapid offset but is associated with a greater incidence of PONV. Nonsteroidal antiinflammatory drugs or acetaminophen, administered by mouth before the operation, or administered intravenously during the operation, demonstrate benefit in terms of patient comfort at lower opioid doses when evaluated postoperatively. The use of nonsteroidal agents is associated with increased postoperative bleeding, particularly in head and neck operations, and should be avoided in these procedures. Gabapentin (600 mg – 1200 mg) taken orally prior to the operation appears to have some benefit in reducing postoperative pain, but side effects may warrant a more selective approach for use in the perioperative period. Infiltration of surgical incision sites with local anesthetic agents has also been demonstrated to reduce opioid needs and improve postoperative comfort. There is no evidence that infiltrating the surgical site prior to incision impacts patient comfort. Installation of local anesthetic agents on surgical beds (e.g., cholecystectomy site) or intraarticular loading of opioids or local anesthetics appear to have only minimal short-lived benefit on patient comfort even though these practices are commonly performed.

Issues in the postanesthesia care unit

The main source for unexpected delayed discharge or hospital admission after ambulatory surgical procedures is PONV. Without prophylactic intervention, PONV occurs in 20% to 30% of the general surgical population, with higher rates in at-risk patients (Box 169-1). At this time, antiemetic medications used in anesthesia are relatively inexpensive and have minimal side effects (e.g., ondansetron), affording their routine use without significant concerns regarding overall cost or complications; the numbers required to treat to demonstrate an advantage of prophylactic antiemetic therapy is very low. Transdermal scopolamine appears to augment the effects of other antiemetics, particularly in patients with a history of motion sickness. Scopolamine should be used cautiously in men with symptoms of prostatic hypertrophy in whom urinary retention may become problematic. Although patients may initially feel well and recover from their anesthesia uneventfully, PONV may occur several hours postoperatively, suggesting a contribution from oral analgesic agents. More attention appears to be needed for improving oral analgesic-related nausea and vomiting.

The main source of patient complaint after ambulatory surgery is pain. One of the most important sources for moderate-to-severe postoperative pain is preoperative pain. Younger age is also associated with increased postoperative pain, with speculation being that younger people are more active and more likely to attempt resumption of usual activities earlier than are the elderly. Sex is not a predictor of postoperative pain but does influence the incidence of PONV.

Increasingly, prompt patient recovery from ambulatory surgical procedures, sometimes facilitated by PNB or neuraxial blockade, sometimes facilitated by new potent, ultrashort-duration medications, is allowing patients to bypass the postanesthesia care unit (PACU) immediately following the operation. Criteria addressing level of consciousness, hemodynamic stability, adequate oxygenation at low inspired O₂ concentrations, and the absence of PONV or significant pain may safely allow bypass of the PACU and improve efficiency. Reducing the number of patients in a PACU requiring treatment allows nursing resources to be better allocated and focused or to be reduced overall. The cost of newer anesthetic agents used in ambulatory settings could be offset by reduced PACU utilization.

Although the goal for patients treated at ambulatory surgical centers is to have prompt recovery and return to their preoperative state, except for those given only local anesthesia, none should be considered competent to drive home following the procedure. Any patient who was provided sedation in any form requires an escort who must remain present and immediately available for 24 h following discharge. The unescorted patient undergoing any procedure in which sedation is provided requires admission for observation.