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General information on Ambulatory Anesthesia

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Chapter 32
Ambulatory Anesthesia
J. Lance Lichtor
Key Points
  • Procedures appropriate for ambulatory surgery are those associated with postoperative care that is easily managed at home and with low rates of postoperative complications that require intensive physician or nursing management.
  • Whatever their age, ambulatory surgery is no longer restricted to patients of 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 the 2006 ASA 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, that the procedure can also be performed as an ambulatory procedure.
  • For adults, airflow obstruction has been shown to persist for up to 6 weeks after viral respiratory infections. For that reason, surgery should be delayed if an adult presents with a URI until 6 weeks have elapsed.
  • In 1999, the ASA published practice guidelines for preoperative fasting. The guidelines allow a patient to have a light meal up to 6 hours before an elective procedure and support a fasting period for clear liquids of 2 hours for all patients.
  • In a meta-analysis of peripheral nerve and centroneuraxial blocks compared to general anesthesia, time until discharge from the ambulatory surgery unit was no different for the three groups.
  • Postoperative pain control is best with regional techniques.
  • Nerve blocks using catheters can be placed before surgery that can be used to provide analgesia after the operation.
  • After induction doses of propofol or thiopental, impairment after thiopental can be apparent for up to 5 hours, but only for 1 hour after propofol.
  • Although many factors affect the choice of agents for maintenance of anesthesia, two primary concerns for ambulatory anesthesia are speed of wake-up and incidence of postoperative nausea and vomiting.
  • It is important to distinguish between wake-up time and discharge time. Patients may emerge from anesthesia with desflurane and nitrous oxide significantly faster than after propofol or sevoflurane and nitrous oxide, though the ability to sit up, stand, and tolerate fluids and the time to fitness for discharge may be no different.
  • Nausea, with or without vomiting, is probably the most important factor contributing to a delay in discharge of patients and an increase in unanticipated admissions of both children and adults after ambulatory surgery.
  • In addition to the PACU, many ambulatory surgery centers in the United States have another area, often known as a phase II recovery room, where patients may stay until they are able to tolerate liquids, walk, and/or void.
Place, Procedures, and Patient Selection
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. Physicians' offices may also serve for procedures. 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. Some hospitals have lost emergency department coverage for an entire surgical specialty because that surgical specialty works exclusively in a freestanding facility.
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The Centers for Medicare and Medicaid Services (CMS) is the U.S. federal agency that administers Medicare. CMS, in a set of regulations that were disclosed in July 2007, generally will pay ambulatory centers 65% of what hospital outpatient surgical facilities receive. For device-intensive procedures, though, ambulatory surgery centers will be paid the same as hospitals. For procedures that usually are performed in an office, ambulatory surgery centers will receive the lesser of 65% or Medicare's standard physician practice fee. This payment rate will be phased in from 2008 to 2011. The payment system may force some ambulatory facilities to decide whether they accept Medicare patients. At that time also, CMS added more than 700 procedures to the acceptable list of ambulatory procedures, making the total number of covered procedures about 3,300.
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 surgery.1 Patients receive one point if they are older than 65 years, have an operating time longer than 120 minutes, cardiac diagnoses, peripheral vascular disease, cerebrovascular disease, malignancy, positive human immunodeficiency virus status; and if regional anesthesia is used. Patients who receive general anesthesia get 2 points. Patients with a score of 3 have 21 times the odds of hospital admission of those with a score of 0 or 1, and patients with scores >3 have 32 times the odds.
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. Free-standing dialysis facilities commonly receive blood shipped from a blood bank located elsewhere and the same can be set up with free standing ambulatory surgery facilities. The key is to have proper procedures established.
Some have wondered about the safety of performing liposuction in an office, following reports of death after the procedure in Florida. Thrombophlebitis was the cause of death in 9 of 11 patients who died in Florida from 2000 to 2006 after abdominoplasty and liposuction.2 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 if their age is <60 weeks but they also have a history of chronic lung or neurologic disease, or who have anemia (hemoglobin <6 mmol/L) should be monitored for 12 hours after their procedure because they are at risk of developing apnea even without a history of apnea.4 Infants older than 46 weeks and <60 weeks without disease should be monitored for 6 hours after their procedure. 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.5 Intravenous caffeine, 10 mg/kg, may help prevent apnea in infants (see also Chapter 44).
At the other extreme of life, advanced age alone is not a reason to disallow surgery in an ambulatory setting. Age, however, does affect the pharmacokinetics of drugs. Even short-acting drugs such as midazolam and propofol have decreased clearance in older individuals. In addition, as previously mentioned, 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.6 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 258 morbidly obese patients who underwent outpatient surgery, compared with patients who were not morbidly obese, there was not a greater incidence of unplanned admissions, minor complications, or unplanned contact with health care professionals.7 In another study, 3,900 patients received a risk factor questionnaire after ambulatory surgery; symptoms were not related to body mass index.8 The ASA has published practice guidelines for the perioperative management of patients with OSA.9 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 32-1 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 someone to 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 hospital. Patients for certain procedures such as laparoscopic cholecystectomy or transurethral resection of the prostate should live close to the ambulatory
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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.
Table 32-1 Consultant Opinions Regarding Procedures that may be Performed Safely on an Outpatient Basis for Patients at Increased Perioperative Risk From Obstructive Sleep Apnea
Type of Surgery/Anesthesia Consultant Opinion
Superficial surgery/local or regional anesthesia Agree
Superficial surgery/general anesthesia Equivocal
Airway surgery (adult, e.g., UPPP) Disagree
Tonsillectomy in children <3 years old Disagree
Tonsillectomy in children >3 years old Equivocal
Minor orthopaedic surgery/local or regional anesthesia Agree
Minor orthopaedic surgery/general anesthesia Equivocal
Gynecologic laparoscopy Equivocal
Laparoscopic surgery, upper abdomen Disagree
Lithotripsy Agree
UPPP, uvulopalatopharyngoplasty.
From Gross JB, Bachenberg KL, Benumof JL et al: Practice guidelines for the perioperative management of patients with obstructive sleep apnea: A report by the American Society of Anesthesiologists Task Force on Perioperative Management of patients with obstructive sleep apnea. Anesthesiology 2006; 104: 1081, with permission.
Preoperative Evaluation and Reduction of Patient Anxiety
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 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. In a study of the usefulness of a preoperative screening telephone call, patients were less likely to cancel surgery if they had been screened beforehand.10 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., nothing to eat or drink after midnight, 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 with 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.11
Automated history-taking may also prove beneficial during the screening of a patient. Computerized questionnaires or checklists with plastic overlays automate the taking 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.
Upper Respiratory Tract Infection
For adults, airflow obstruction has been shown to persist for up to 6 weeks after viral respiratory infections. For that reason, surgery should be delayed if an adult presents with an upper respiratory infection (URI) until 6 weeks have elapsed. In the case of children, whether surgery should be delayed for that length of time is questionable. In one study of 1,078 children 1 month to 18 years of age, risk factors for adverse respiratory events in children with URIs were examined.12 The authors could find no difference in laryngospasm or bronchospasm if the children had active URIs, a URI within 4 weeks, or no symptoms. But children with active or recent URIs had more episodes of breath holding, incidences of desaturation <90%, and more respiratory events compared with children without symptoms (Fig. 32-1). Although a case may be cancelled because a child is symptomatic, the child may develop another URI when the procedure is rescheduled. In children, URI has not been shown to be associated with an increased length of stay in the hospital after a procedure. Independent risk factors for adverse respiratory events in children with URIs include use of an endotracheal tube (versus use of a laryngeal mask airway [LMA] or face mask), history of prematurity, history of reactive airway disease, history of parental smoking, surgery involving the airway, presence of copious secretions, and nasal congestion. Generally, if a patient with a URI has a normal appetite, does not have a fever or an elevated respiratory rate, and does not appear toxic, it is probably safe to proceed with the planned procedure.
Restriction of Food and Liquids Before Ambulatory Surgery
To decrease the risk of aspiration of gastric contents, patients are routinely asked not to eat or drink anything (non per os [NPO]
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or “nothing by mouth”) for at least 6 to 8 hours before surgery. However, prolonged fasting can be detrimental to a patient. Indeed, in one study infants who fasted longer had greater drops in intraoperative blood pressure (Fig. 32-2).13 No trial has shown that a shortened fluid fast increases the risk of aspiration. Gastric volumes are actually less when patients are allowed to drink some fluids before surgery. Admittedly, though, the majority of studies have not been specifically performed in individuals who are at an increased risk for aspiration. An excellent review of this topic has been published.14
Figure 32-1. Adverse respiratory events are similar between children with an upper respiratory infection (URI) and a recent URI, and this similarity persists for at least 4 weeks after the URI.12 *p <0.05 versus no URI. (Reprinted from Tait AR, Malviya S, Voepel-Lewis T et al: Risk factors for perioperative adverse respiratory events in children with upper respiratory tract infections. Anesthesiology 2001; 95: 299, with permission.)
Figure 32-2. Blood pressure is lower in children 1 to 6 months of age who fast more than 8 hours, compared with those who fast for less than 4 hours.13 Illustrated are changes in systolic blood pressure from baseline to the time when 2 minimum alveolar concentration halothane was reached in 250 infants and children. *p <0.05 versus 0- to 4-hour fasting group. (Reprinted from Friesen RH, Wurl JL, Friesen RM: Duration of preoperative fast correlates with arterial blood pressure response to halothane in infants. Anesth Analg 2002; 95: 1572, with permission.)
In 1999, the ASA published practice guidelines for preoperative fasting. The guidelines allow a patient to have a light meal up to 6 hours before an elective procedure and support a fasting period for clear liquids of 2 hours for all patients. Coffee and tea are considered clear liquids. Coffee and tea drinkers should follow fasting guidelines but should be encouraged to drink coffee prior to their procedure because physical signs of withdrawal (e.g., headache) can easily occur. It is not clear if the guidelines should apply to patients with diabetes or dyspepsia. There is some evidence that shorter periods of preoperative fasting are accompanied by less postoperative nausea and vomiting (PONV). Yet, it is unclear whether rehydration during surgery is equivalent to a shorter fast before surgery in relation to PONV.
To ensure patients are optimally medically managed before their outpatient surgery, given the fact that clear liquids can be taken up to 2 hours before surgery, patients should be encouraged to take their chronic medications.
Anxiety Reduction
Clearly, some patients scheduled to undergo surgery are anxious, and they are probably anxious long before they come to the outpatient area. Preoperative reassurance from nonanesthesia staff and providing booklets with information about the procedure also reduce preoperative anxiety. However, use of booklets is less effective than a preoperative visit by the anesthesiologist. Audiovisual instructions also reduce preoperative anxiety. However, not all outpatients are anxious. For example, although insomnia and anxiety are related, in a study of sleep characteristics of outpatients before elective surgery, no differences in sleep quality were found between patients before surgery and a community control group,15 Indeed, physicians often tend to overestimate the level of anxiety that patients are actually experiencing.16 Some operations can certainly generate more anxiety than others. If in doubt about patient anxiety, ask the patient.
Like adults, children should have some idea of what to expect during a procedure. But much of a child's anxiety before surgery concerns separation from a parent or parents. A child is more likely to demonstrate problematic behavior from the time of separation from parents to induction of anesthesia if a procedure has not been explained preoperatively. Parents and children need to be involved in some preoperative discussions together so the anxiety of the parents is not transmitted to the child. The transmission of anxiety is at least as problematic as is the separation itself (e.g., experiences of children being left with babysitters). If the parents are calm and can effectively manage the physical transfer to a warm and playful anesthesiologist or nurse, premedication is not necessary. Semisedation may be awkward, and recovery after premedication may be prolonged.
If a child is accompanied by a parent during the induction of anesthesia, the child's anxiety can be reduced. Some parents can become upset when they see their anesthetized child, who appears to be dead, albeit breathing and with a beating heart. Separation anxiety on the part of the parents is probably no different if the child is awake or asleep. Those children who have preoperative instructions and coaching both for themselves and their families, and their parent/s present during induction have less anxiety preoperatively, less postoperative delirium, shortened discharge time after surgery, and reduced analgesic consumption after surgery.17
Family-centered care has become popular and is useful for decreasing preoperative anxiety in children. In one study, 408 children undergoing elective ambulatory surgery received either standard care, had a parent present during induction, received oral midazolam prior to surgery, or received family-centered care prior to surgery.17 Family-centered therapy consisted of providing the families of children with a videotape, three pamphlets, and a mask practice kit during their preoperative visit. One pamphlet was designed to help parents understand what to expect on the day of surgery and some recommendations for them to decrease their anxiety and their child's anxiety. Another gave them instructions for distracting their child on the day of surgery. A third gave instructions to teach the child what to do when in the operating room (OR), such as getting on the OR bed, and using the mask for induction. Parents were also given an induction mask, and a hairnet. On the day of surgery, children in the family-centered therapy group were given toys, designed to be age-appropriate and distracting (e.g., puzzles, brainteasers), unlike the other children who were simply given toys. Patients in the family-centered group, compared with the other three groups, preoperatively were less anxious. Parents were also less anxious. In addition, the patients had less severe emergence delirium symptoms, needed less fentanyl postoperatively, and were discharged earlier.
Managing the Anesthetic: Premedication
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.
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Most premedicants do not prolong recovery when given in appropriate doses for appropriate indications, although drug effects may be apparent even after discharge.
Benzodiazepines
Although historically many classes of drugs (e.g., barbiturates, antihistamines) have been used to reduce anxiety and induce sedation, benzodiazepines are currently the drugs most commonly used. Midazolam is the benzodiazepine most commonly used preoperatively. It can be used intravenously and orally. In adults, it can be used to control preoperative anxiety and, during a procedure alone or in combination with other drugs, for intravenous sedation. For children, oral midazolam in doses as small as 0.25 mg/kg produces effective sedation and reduces anxiety.18 With this dose, most children can be effectively separated from their parents after 10 minutes and satisfactory sedation can be maintained for 45 minutes. Discharge may be delayed, though, when given before a short procedure. Oral diazepam is useful to control anxiety in adult patients, either the day before surgery or the day of surgery and before an intravenous line has been inserted.
Fatigue associated with the effects of anxiolytics may delay or prevent the discharge of patients on the day of surgery, although more frequently patients are not discharged because of the effects of the operation. With regard to anesthesia effects, patients normally stay in the hospital not because they are too sleepy but because they are nauseous. In adults, particularly when midazolam is combined with fentanyl, patients can remain sleepy for up to 8 hours (Fig. 32-3).19 Although children may be sleepier after oral midazolam, discharge times are not affected.
Figure 32-3. Patients can remain sleepy after receiving midazolam and fentanyl, even 8 hours after drug administration.19 The abscissa represents time (hours) after sedation. The ordinate represents sleep latency (i.e., time to fall asleep). Data are the mean time to fall asleep. An individual is sleepier if less time is required to fall asleep. Subjects receiving the midazolam and fentanyl combination were much sleepier than the same subjects receiving other types of sedation. Although not seen in the figure, up to 8 hours after sedation, some subjects were still sleepier than before they received drug. (Reprinted from Lichtor JL, Alessi R, Lane BS: Sleep tendency as a measure of recovery after drugs used for ambulatory surgery. Anesthesiology 2002; 96: 878, with permission.)
At proper doses, neither midazolam nor diazepam place patients at any additional risk for cardiovascular and respiratory depression. Decreased oxygen saturation has been reported after injection of midazolam. Routine administration of supplemental oxygen with or without continuous monitoring of arterial oxygenation is recommended whenever benzodiazepines are given intravenously. This precaution is important not only when midazolam is given as a premedicant, but also when it is used alone or with other drugs for conscious sedation. The potential for amnesia after premedication is another concern, especially for patients undergoing ambulatory surgery. Anterograde amnesia certainly occurs. Although benzodiazepines facilitate retrograde memory, in one study there was no immediate retrograde amnesia after intravenous midazolam, 2 to 10 mg.20 For benzodiazepines, the effects on memory are separate from the effects on sedation. In addition, amnesia is not simply an effect of drug administration but, among other factors, it is also a function of stimulus intensity.
Opioids and Nonsteroidal Analgesics
Opioids can be administered preoperatively to sedate patients, control hypertension during tracheal intubation, and decrease pain before surgery. Meperidine (but not morphine or fentanyl) is sometimes helpful in controlling shivering in the OR or the postanesthesia care unit (PACU), although treatment is usually instituted at the time of shivering and not in anticipation of the event. The effectiveness of opioids in relieving anxiety is controversial and probably nonexistent, particularly in adults.
Opioids are useful in controlling hypertension during tracheal intubation. Opioid premedication prevents increases in systolic pressure in a dose-dependent fashion. After tracheal intubation, systolic, diastolic, and mean arterial blood pressures sometimes decrease below baseline values.
Preoperative administration of opioids or nonsteroidal anti-inflammatory drugs (NSAIDs) may be useful for controlling pain in the early postoperative period. In one study, controlled-release oxycodone, 10 mg, when given before surgery, was effective in managing pain after laparoscopic tubal ligation surgery and was even associated with less PONV.21 In a similar study of patients undergoing laparoscopic tubal ligation surgery, though, premedication with controlled-release oxycodone, 15 mg, did not improve the postoperative pain management.22
Celecoxib, up to 400 mg, is effective in reducing postoperative pain.23 Ibuprofen or acetaminophen can be given rectally to children around the time of induction. If rectal acetaminophen is used in children, an initial loading dose of 40 mg/kg is appropriate; subsequent doses of 20 mg/kg every 6 hours can be used.24 And, when preoperative rectal acetaminophen is combined with ketoprofen, particularly for more painful procedures, postoperative pain is less than when the drugs are given individually.25
Preoperative sedation is not needed for every patient. The following is our practice when patients require drugs to relieve anxiety. For the patient who has been seen at least 24 hours before a scheduled procedure and expresses a desire for medication to relieve anxiety or has anxiety that cannot be relieved with comforting, oral diazepam, 2 to 5 mg per 70 kg body weight, is prescribed for the night before and at 6:00 AM on the day of surgery (even if surgery is scheduled for 1:00 PM or later). For patients seen for the first time in the preoperative holding area who seem to need medication, midazolam, 0.01 mg/kg, is administered intravenously, or the patient is brought into the OR and propofol, 0.7 mg/kg, is injected intravenously. For children, when necessary, oral midazolam, 0.25 mg/kg, is
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administered in the preoperative holding area. When the child is asleep, acetaminophen, 40 mg/kg rectally, and ketorolac, 0.5 mg/kg intravenously, are administered prior to initiation of surgery.
Intraoperative Management: Choice of Anesthetic Method
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.26 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.
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.27 Conversely, in a study of patients undergoing shoulder surgery who received either general or regional anesthesia, patients who received regional anesthesia were more often able to bypass first-stage recovery, had less pain, were able to ambulate, and were eligible for discharge earlier than the general anesthesia group.28 In a meta-analysis of peripheral nerve and centroneuraxial blocks compared with general anesthesia, time until discharge from the ambulatory surgery unit was no different for the three groups.29 Interestingly also, postoperative nausea in the centroneuraxial 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.30 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.
For some procedures such as arthroscopy, patients might prefer a regional anesthetic simply because they are curious and want to watch the surgery.31 Postoperative pain is less after regional anesthesia, which is discussed in more detail later in this section. Also, with regional anesthesia or sedation, some of the side effects of general anesthesia can be avoided, although no form of medical care is without side effects. Whenever drugs are given that affect memory, patients might complain that they do not remember events that occur after the procedure. Although with regional anesthesia more time is required to place a block than it takes to induce a general anesthetic, a meta-analysis of several studies showed this increased time to be on average no more than 8 to 9 minutes.29 In one survey of orthopaedic surgeons, the majority of surgeons who direct their patients' choice of anesthetic choose regional anesthesia, although the potential delay in establishing a block and perceived unpredictable success detracted from their enthusiasm with regional anesthesia (Fig. 32-4).32
Figure 32-4. Operating room (OR) delays are the major reasons orthopaedic surgeons do not favor regional anesthesia.32 GA, general anesthesia. (Reprinted from Oldman M, McCartney CJ, Leung A et al: A survey of orthopedic surgeons' attitudes and knowledge regarding regional anesthesia. Anesth Analg 2004; 98: 1486, with permission.)
One adverse effect associated with spinal anesthesia is headache, but headaches are also experienced by patients after general anesthesia. The incidence of headache after either technique may be similar especially when smaller spinal needles are used. Patients may experience backache after spinal anesthesia, although sore throat and nausea are higher after general anesthesia than spinal type. Larger studies of patients undergoing ambulatory surgery are needed that compare sedation with regional and general anesthesia.
Regional Techniques
Local anesthesia and regional anesthesia have long been used for ambulatory surgery. As early as 1963, for example, 56% of ambulatory procedures were performed with the use of these techniques.33 Regional techniques commonly used for ambulatory surgery, in addition to spinal and epidural anesthesia, include local infiltration, brachial plexus and other peripheral nerve blocks, and intravenous regional anesthesia. General anesthesia can also be supplemented with regional nerve blocks.
Performing a block takes longer than inducing general anesthesia, and the incidence of failure is higher. Unnecessary delays can be obviated by performing the block beforehand in a preoperative holding area. Because a postoperative nursing intervention, usually associated with general anesthesia, is associated with a 27- to 45-minute delay, the increased setup time for a regional anesthetic may be associated with a shorter time to discharge.34 Postoperative pain control is best with regional techniques.
An occasional patient may experience syncope when the needle for the regional block is inserted. In the experience of oral and maxillofacial surgeons in Massachusetts in the late 1990s, 1 of 160 patients fainted when local anesthesia was injected.35 When sedation accompanies local anesthesia injection, the incidence of syncope is reduced. Patients usually experience less postoperative pain when local or regional anesthesia has been used. Patients may still have a numb extremity (e.g., after a brachial plexus block) but otherwise meet all criteria for discharge. In such instances, the extremity must
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be well protected (e.g., with a sling for an upper extremity procedure) and patients must be cautioned to protect against injury because they are without normal sensations that would warn them of vulnerability. Reassurance that sensation will return should be provided.
Spinal Anesthesia
Children
Spinal anesthesia is used in some centers particularly for children undergoing inguinal hernia repair. One group described a series of >1,000 patients where spinal anesthesia was used for children aged 6 months to 14 years for procedures on the lower part of the body.36 Muscle relaxation with the technique was excellent. In this series, all children left the OR awake and pain-free. The anesthesiology team used 0.5% hyperbaric bupivacaine at a dose of 0.2 mg/kg. Theoretically, PONV should be less after spinal anesthesia. That was the case in one study, although discharge times or patient satisfaction were no different when compared with patients who received general anesthesia.37
Adults
The use of spinal needles with pencil point, noncutting tips has prompted a resurgence of spinal anesthesia for ambulatory surgery in adults. Spinal anesthesia is suitable for pelvic, lower abdominal, and lower extremity surgery. One group described use of spinal anesthesia for ambulatory laparoscopic cholecystectomy with spinal needle insertion at L10, although even these authors recommended their technique not be used routinely because of the potential for direct contact of neural tissue by the spinal needle.38
Motor block of the legs may delay a patient's ability to walk. However, the use of a short-acting local anesthetic will minimize this problem. Nausea is much less frequent after epidural or spinal anesthesia than after general anesthesia.
Different drugs and drug concentrations have been used for spinal anesthesia. Lidocaine and mepivacaine are ideal for ambulatory surgery because of their short duration of action, although lidocaine use has been problematic because of transient neurologic symptoms. Transient neurologic symptoms can be seen after other local anesthetics, but the risk is 7 times more after intrathecal lidocaine than after bupivacaine, prilocaine, or procaine.39
Chloroprocaine spinal anesthesia has rapid onset and offset. In a study of nonpatient volunteers, after 40 mg of 2-chloroporcaine, the study participants could void after 110 minutes.40 In that study, when 20 µg of fentanyl was included, regression time to L1 was lengthened and tourniquet tolerance was improved, although overall block length was minimally affected. Forty milligrams of preservative-free 2-chloroporcaine produces a similar onset time and block height when compared with 40 mg of lidocaine.41 In one study, the authors showed that 40 and 50 mg of 2-chloroprocaine provided adequate spinal anesthesia for outpatient procedures lasting 45 to 60 minutes, whereas after 30 mg, the duration of block was inadequate.42
Both ropivacaine and bupivacaine have been used for ambulatory surgical procedures, but recovery time is relatively long. In a study comparing 7.5 mg bupivacaine and 15 mg ropivacaine for spinal anesthesia for knee arthroscopy, time to ambulation for both drugs was about 5 hours.43
Although headache is a common complication of lumbar puncture, smaller-gauge needles result in a lower incidence of postdural puncture headache. For those patients who do receive spinal anesthesia, it is incumbent on the anesthesiologist and the facility to have follow-up with telephone calls to ensure no disabling symptoms of headache have developed. If the headache does not respond to bed rest, analgesics, and oral hydration, the patient must return to the hospital for a course of intravenous caffeine therapy or an epidural blood patch.
Spinal anesthesia should not be avoided in ambulatory surgery patients simply because they may be more active postoperatively than inpatients. Bed rest does not reduce the frequency of headache. Indeed, early ambulation may decrease the incidence. Further study is needed to assess the relative risk–benefit ratio of spinal anesthesia as a technique for the ambulatory surgery patient.
Epidural and Caudal Anesthesia
Epidural anesthesia takes longer to perform than spinal anesthesia. Onset with spinal anesthesia is more rapid, although recovery may be the same with either technique. In one study of patients undergoing knee arthroscopy, spinal anesthesia with small-dose lidocaine and fentanyl was compared with 3% 2-chloroporcaine administered in the epidural space: intraoperative conditions, discharge characteristics and times, and recovery profiles were similar.44 Also, failure rates for the two techniques, although low, were the same. Some studies suggest that bicarbonate can be added to solutions for faster onset of epidural anesthesia. An advantage of the epidural block is that it can be performed outside the OR, and after the surgical procedure is completed, the problem of postdural puncture headache is usually avoided.
Caudal anesthesia is a form of epidural anesthesia commonly used in children before surgery below the umbilicus as a supplement to general anesthesia and to control postoperative pain. Bupivacaine, 0.175 to 0.25%, or ropivacaine, 0.2%, in a volume of 0.5 to 1.0 mL/kg, may be used; a safe maximal dose is 2.5 mg/kg. Epinephrine, 1:200,000, when added to the anesthetic solution, may allow earlier detection of intravenous, rather than epidural, injection. Other useful albeit controversial additives for increasing duration of blockade include opioids, ketamine, clonidine, and neostigmine.45 The block may be more difficult in children, particularly those who weigh >10 kg and are obese, if landmarks for the block are difficult to locate. The block is usually administered while the child is anesthetized. After injection, the depth of general anesthesia can be reduced. Because of better pain control after a caudal block, children can usually ambulate earlier and be discharged sooner than without a caudal block. Pain control and discharge times are no different whether the caudal block is placed before surgery or after it is completed.
Nerve Blocks
In a survey mailed to members of the Society for Ambulatory Anesthesia in 2001, there was shown to be widespread use of axillary and interscalene blocks for surgery in the upper extremity, and of ankle and femoral blocks for lower extremity surgery.46 Nerve blocks improve postoperative patient satisfaction—PONV and postoperative pain are less. Costs are also less. One nonrandomized study of outpatients in a university setting showed that PACU admissions, hospital cost, and unexpected hospital admission were all reduced when nerve block was used for anterior cruciate ligament repair reconstruction.47 For knee arthroscopy, psoas compartment block or spinal anesthesia is superior to general anesthesia in terms of postoperative pain management and patient satisfaction.48 After more complex knee surgery, patients who received femoral-sciatic nerve block required fewer nursing interventions for pain; and, if patients received either that block or only a femoral nerve block, unplanned hospital admissions were less compared with patients who underwent the procedure without a block.49 In a comparison of patients who underwent either infraclavicular brachial plexus block or general anesthesia for upper extremity surgery, after brachial plexus block more patients were able to bypass phase I PACU care, had less pain on PACU arrival, and were discharged much sooner (Fig. 32-5).50
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Figure 32-5. Recovery was faster when an infraclavicular brachial plexus block with a short-acting local anesthetic was used, compared with general anesthesia and wound infiltration for outpatients undergoing hand and wrist surgery.50 Times are calculated from the end of anesthesia. (Reprinted from Hadzic A, Arliss J, Kerimoglu B et al: A comparison of infraclavicular nerve block versus general anesthesia for hand and wrist day-case surgeries. Anesthesiology 2004; 101: 127, with permission.)
Certain procedures can be quite painful, and hospitalization may be required to control pain. Nerve blocks using catheters that can be used to provide analgesia after the operation can be placed before surgery. Paravertebral somatic nerve block can be used for breast surgery, followed by a continuous perineural infusion of local anesthetic at home for 24 to 48 hours.51 Perineural catheters in the sciatic nerve through the popliteal fossa can be used to control pain after foot surgery for both adults and children.52,53 Femoral nerve catheters left in for about 2 days after anterior cruciate ligament reconstruction surgery after patients were discharged have been shown to decrease postoperative pain up to 4 days after surgery.54 Interscalene perineural catheters, kept in for 4 days after surgery, have been used for patients undergoing moderately painful shoulder surgery.55 Compared with patients who have regional anesthesia for surgery and then treatment afterward with narcotics, patients who go home with the interscalene perineural catheters attached to an infusion pump with ropivacaine can leave the hospital earlier the day after surgery, and once home have less pain and require less narcotics (Fig. 32-6). Continuous cervical paravertebral block may also be useful for analgesia after shoulder surgery.56 Popliteal catheters have been used for lower extremity surgery such as hallux valgus surgery.57
Patients who go home with catheters inserted must be taught about pump function, understand signs of local anesthesia toxicity, and have someone else at home who can provide assistance. In addition, the patients must be able to communicate with someone by phone. The number of patients who have been sent home with catheters is increasing but is not large. More study is needed in order to demonstrate patient safety.
Sedation and Analgesia
Many patients who undergo surgery with local or regional anesthesia prefer to be sedated and to have no recollection of the procedure. Sedation is important, in part, because injection with local anesthetics can be painful and lying on a hard OR table can be uncomfortable. Levels of sedation vary from light, during which a patient's consciousness is minimally depressed, to very deep, in which protective reflexes are partially blocked and response to physical stimulation or verbal command may not be appropriate. When patients are unsuitable for outpatient general anesthesia, surgery can often be performed if local or regional anesthesia is supplemented with conscious sedation. However, serious risk, such as death, is probably no different after sedation than after general anesthesia. Children who have surgery usually will not remain immobile unless they are deeply sedated or receive general anesthesia.
Figure 32-6. Patients who continued to receive an interscalene infusion of ropivacaine after surgery could be discharged home much earlier compared with patients who received postoperative narcotics.55 Discharge criteria included adequate analgesia, independence from intravenous opioids, and the ability to tolerate at least 50% of passive shoulder motion targets during physical therapy. (Reprinted from Ilfeld, BM, Vandenborne, K, Duncan, PW, et al: Ambulatory continuous interscalene nerve blocks decrease the time to discharge readiness after total shoulder arthroplasty: A randomized, triple-masked, placebo-controlled study. Anesthesiology 2006; 105: 999, with permission.)
For adults, the proper dose might be selected by having the patient control the dosage. Yet, at least for ambulatory surgical procedures, patient-controlled sedation is not popular. This may be because a member of the anesthesia care team must be continuously present anyway.
General Anesthesia
The drugs selected for general anesthesia determine how long patients stay in the PACU after surgery, and for some patients, whether they can be discharged to go home.
Induction
The popularity of propofol as an induction agent for outpatient surgery in part relates to its half-life: the elimination half-life of propofol is 1 to 3 hours, shorter than that of methohexital (6 to 8 hours) or thiopental (10 to 12 hours). Although the effect of drugs given for induction seems to be transient, these drugs can depress psychomotor performance for several hours. After induction doses of propofol or thiopental, impairment after thiopental can be apparent for up to 5 hours, but only for 1 hour after propofol.
Pain on injection can be a problem with propofol. Pain is more likely on injection into dorsal hand veins and is minimized if forearm or larger antecubital veins are used. Some individuals, though, experience pain if the drug is injected into proximal larger veins. Nonetheless, thrombophlebitis does not appear to be a problem after intravenous administration of this agent, whereas it can be evident after thiopental.
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Intravenous lidocaine, 0.2 mg/kg, can be used to decrease the incidence and severity of pain; other techniques have been tried, including ketamine, 0.1 mg/kg, immediately before propofol injection or lidocaine, 20 mg, plus metoclopramide, 10 mg.58,59 Some have questioned the stability of mixing more than 20 mg lidocaine with 20 mL propofol.60
Most children and some adults prefer not to have an intravenous catheter inserted before the start of anesthesia. Sevoflurane has a relatively low blood-gas partition coefficient and the speed of induction is similar to, albeit somewhat slower than, that of propofol. Induction with sevoflurane can be hastened when the patient is told to breathe out to residual volume, take a vital capacity breath through a primed anesthesia circuit, and then hold the breath.
For short procedures, some patients may not require neuromuscular-blocking drugs; others may need brief paralysis (e.g., with succinylcholine) to facilitate tracheal intubation. Nondepolarizing drugs can be used to facilitate intubation and also during the procedure. Nondepolarizing drugs such as rocuronium have rapid onset times that are similar to those with succinylcholine. Of course, paralysis is not needed to insert an endotracheal tube; drug combinations such as propofol, alfentanil or remifentanil, and lidocaine obviate the need for paralysis.61 Succinylcholine should be used with caution in children because of the possibility of cardiac arrest related to malignant hyperthermia or unsuspected muscular dystrophy, particularly Duchenne disease.
Maintenance
Although many factors affect the choice of agents for maintenance of anesthesia, two primary concerns for ambulatory anesthesia are speed of wake-up and incidence of PONV.
Anesthesia Maintenance and Wake-Up Times
Time to recovery may be measured by various criteria; however, for an ambulatory center, a patient may be considered awake when he or she is able to leave the center. Actual discharge from an ambulatory center, though, may depend on administrative issues such as a written order from a surgeon or anesthesiologist. The time necessary before a patient can be taken from the OR after completion of surgery, or a patient's ability to skip the PACU and go directly to a step-down unit, may be directly related to the anesthetic and may result in cost savings for an institution. Does choice of maintenance agent affect recovery after anesthesia? Propofol, desflurane, and sevoflurane have characteristics that make them ideal for maintenance of anesthesia for ambulatory surgery. Propofol has a short half-life and, when used as a maintenance agent, results in rapid recovery and few side effects. Desflurane and sevoflurane, halogenated ether anesthetics with low blood-gas partition coefficients, seem to be ideal for general anesthesia for ambulatory surgery. Sevoflurane, unlike desflurane, facilitates a smooth inhalation induction of anesthesia, the preferred technique to ensure rapid recovery of children in ambulatory surgery centers.
It is important to distinguish between wake-up time and discharge time. Patients may emerge from anesthesia with desflurane and nitrous oxide significantly faster than after propofol or sevoflurane and nitrous oxide, although the ability to sit up, stand, and tolerate fluids and the time to fitness for discharge may be no different. When the bispectral index (BIS) or other guide of anesthetic depth is used, the difference between drugs and wake-up times may not be as great.62 Conversely, if fast wake-up times can translate to bypass of phase I, there may be cost savings.
Intraoperative Management of Postoperative Nausea and Vomiting
Nausea, with or without vomiting, is probably the most important factor contributing to a delay in discharge of patients and an increase in unanticipated admissions of both children and adults after ambulatory surgery. Patients hate vomiting. Studies have been performed in which patients are asked how much they would pay to avoid PONV or postoperative pain. Patients are willing to pay the most to prevent either of these outcomes, although the actual amount is a function, in part, on patient income.63 Women, especially those who are pregnant, have a higher incidence of PONV. Other risk factors include a previous history of motion sickness or postanesthetic emesis, surgery within 1 to 7 days of the menstrual cycle, not smoking, and procedures such as laparoscopy, lithotripsy, major breast surgery, and ear, nose, or throat surgery. The greater the number of risk factors, the greater risk for nausea or vomiting after surgery. Inhalation agents are associated with an increased risk of PONV, particularly in the early stages of recovery; postoperative narcotic use is associated with PONV >2 hours after surgery.64
The vomiting pathway starts peripherally, where emerogenes through enterochromaffin cells in the gastrointestinal tract and/or other sensory neurons activate vagal afferents to the group of brainstem nuclei in the area postrema, the nucleus tractus solitarius, and the dorsal motor nucleus of the vagus. This area in the brain is otherwise known as the vomiting center. Although the pathways for vomiting are not completely understood, the area postrema is highly vascular, lacks a complete blood–brain barrier, and has receptors for neurotransmitters and hormones.65 Receptor antagonists, specifically selective serotonin antagonists (ondansetron, dolasetron, and granisetron), have been shown to have similar efficacy to help alleviate nausea and vomiting. Dopamine antagonists, antihistamines, and anticholinergic drugs are useful and are generally less expensive, but are associated with extensive side effects. Neurokinin (NK1) receptor antagonists may also be useful to control PONV. Therapies useful in controlling PONV include acupuncture (Fig. 32-7).66 supplemental fluid therapy,67 clonidine (perhaps in part because it decreases anesthesia requirement),68 and dexamethasone.69,70 In one study, acupuncture therapy was effective in controlling both PONV and postoperative pain.71 Acupressure is most effective when it is administered after surgery,72 although if, intraoperatively, leads to
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monitor patient paralysis are placed at the P6 acupuncture point, PONV is reduced.73
Figure 32-7. The P6 acupuncture point in relation to other hand structures is illustrated.87 (1) P6 acupuncture point, (2) palmaris long tendon, (3) flexor carpi radialis tendon, (4) median nerve, and (5) palmar aponeurosis. (Reprinted from Wang SM, Kain ZN: P6 acupoint injections are as effective as droperidol in controlling early postoperative nausea and vomiting in children. Anesthesiology 2002; 97: 359, with permission.)
Combination therapy is probably the most effective way to control PONV. Therapy includes avoidance of nitrous oxide; avoidance of inhalation agents; avoidance of muscle relaxant reversal, if clinically indicated; avoidance of narcotics; fluid hydration; and administration of a 5-HT3 antagonist, an antiemetic from a different drug class, and dexamethasone. Risk, of course, is a function of other factors, as previously described. In one study in which combination therapy was used, nausea incidence was <10% and was even lower for certain procedures and types of patients.74
Because of its ability to decrease PONV, propofol is the best general anesthetic for ambulatory anesthesia. For example, in a study of 5,161 patients, propofol, compared with a volatile anesthetic, reduced nausea and vomiting by 19%; and nitrogen compared with nitrous oxide reduced the incidence by 12% (Fig. 32-8).70 Propofol is now generic so the decision to use the drug should not be based on cost.
The use of nitrous oxide for ambulatory anesthesia is an issue because the incidence of emesis may be greater after nitrous oxide than after other inhalation agents. Although many studies have shown that nitrous oxide can be used successfully for ambulatory anesthesia, there is evidence that nitrous oxide should be avoided, except for inhalation induction of anesthesia. In one study of patients undergoing major, albeit not ambulatory, surgery, avoidance of nitrous oxide reduced postoperative complications, including postoperative fever, wound infection, pneumonia, pulmonary atelectasis, and severe nausea or vomiting.75 Whether the changes found in that study would be as dramatic in ambulatory patients is not clear. Yet, many would argue that nitrous oxide is no longer needed except for inhalation induction of anesthesia.
Paralysis
Muscle paralysis for ambulatory anesthesia extends beyond the time of paralysis for intubation, particularly when nondepolarizing drugs are used. The duration of action of rocuronium, vecuronium, rapacuronium, and atracurium ranges from 25 to 40 minutes. Reversal agents must be used unless there is no doubt that muscle relaxation has been fully reversed.
Figure 32-8. Postoperative nausea and vomiting (PONV) is least after a propofol anesthetic with air.70 Illustrated is the incidence of PONV when different anesthetics and different numbers of prophylactic antiemetic treatments are administered. (Reprinted from Apfel CC, Korttila K, Abdalla M et al: A factorial trial of six interventions for the prevention of postoperative nausea and vomiting. N Engl J Med 2004; 350: 2441, with permission.)
Intraoperative Management of Postoperative Pain
Opioids, when given intraoperatively, are useful to supplement both intraoperative and postoperative analgesia. Fentanyl is probably the most popular drug, although all other available narcotics have been tried. All narcotics can cause nausea, sedation, and dizziness, which can delay a patient's discharge. Nonsteroidal analgesics are not effective as supplements during general anesthesia, although they are useful in controlling postoperative pain, particularly when given before skin incision. To control postoperative pain, combination therapy is most useful. (See also the previous discussion on opioids and nonsteroidal analgesics in “Opioids and Nonsteroidal Analgesics.”)
Depth of Anesthesia
Use of BIS, and entropy, or auditory-evoked potential monitors can decrease anesthesia requirement without sacrificing amnesia during general anesthesia. Because less anesthesia is used, titration of anesthesia with these monitors results in earlier emergence from anesthesia. In a meta-analysis of BIS monitoring for ambulatory anesthesia, BIS monitoring was shown to reduce anesthetic use by 19%, with more modest decreases in PACU duration (4 minutes) and PONV (6%; Fig. 32-9).76 Results are even more modest, albeit mixed, in terms of later recovery end points. Sympatholytic drugs, instead of anesthesia, can be used to control autonomic responses to anesthesia. In fact, recovery is faster and side effects are fewer in ambulatory patients whose blood pressure is controlled by sympatholytics instead of inhalation agents.77 In a study of almost 5,000 patients who underwent general anesthesia and who were paralyzed and/or were intubated, awareness was significantly reduced in the group of patients who were monitored with a BIS compared with the group who were not monitored with the BIS.78 Entropy, auditory-evoked potential, and cerebral state monitors are similar to BIS. Because these monitors result in less use of anesthesia, there is the possibility that intraoperative awareness and myocardial ischemia might be increased.
Airways
The use of an LMA, or similar type of airway, provides several advantages for allowing a patient to return to baseline status quickly. Muscle relaxants required for intubation can be avoided. Coughing is less than with tracheal intubation. Anesthetic requirements are reduced. Hoarseness and sore throat are also reduced. Overall, cost savings result with the use of LMAs. Because of gastric insufflation, though, nausea and vomiting may be greater. The use of the LMA has been described for laparoscopic procedures, although the potential for aspiration exists because of an inflated abdomen during laparoscopy.
Figure 32-9. Bispectral index (BIS) (Aspect Medical Systems, Inc., Norwood, MA), monitoring reduces anesthetic consumption, cost to treat postoperative nausea and vomiting (PONV), and postanesthesia care unit (PACU) time; the cost of the electrode reverses cost savings.76 The ordinate represents cost difference per case pooled from three studies (i.e., costs for the control group minus cost for the group that used BIS). The capital cost for the BIS monitor was not included. (Adapted from Liu SS: Effects of bispectral index monitoring on ambulatory anesthesia: A meta-analysis of randomized controlled trials and a cost analysis. Anesthesiology 2004; 101: 311, with permission.)
Management of Postanesthesia Care
Many recovery issues are part of patient selection and perioperative management and must be considered before the patient enters the PACU. Managing common problems in the PACU quickly and effectively is as important as appropriate patient selection and choice of anesthetic technique if the patient is to return home on the day of surgery. The three most common reasons for delay in patient discharge from the PACU are drowsiness, nausea and vomiting, and pain. All three are a function of intraoperative management, but nausea, vomiting, and pain also can be treated in the PACU.
Reversal of Drug Effects
Reversal of muscle relaxants is not unique to the ambulatory surgery patient and is not discussed here. Reversal of opioids may sometimes be necessary. Flumazenil, a benzodiazepine receptor antagonist, has primarily been used to reverse the effects of sedation after endoscopy and spinal anesthesia. Reversal of psychomotor impairment with flumazenil is not complete, and the subjective experience of sedation is not necessarily attenuated. Reversal of amnesia with flumazenil is only partial, and the duration of the reversal effect may not be long enough to be clinically significant. Flumazenil should not be used routinely as a benzodiazepine antagonist, but may be used when sedation appears to be excessive. In addition, reversal of benzodiazepine-induced sedation by flumazenil should not replace appropriate ventilatory assistance and, if necessary, placement of an endotracheal tube.
Nausea and Vomiting
Nausea and vomiting are the most common reasons both children and adults have protracted stays in the PACU or unexpected hospital admission due to anesthesia. Nausea and vomiting are also the most common adverse effect in patients in the PACU. Much research has been undertaken to study prophylactic treatment of this problem before surgery, as well as techniques in the OR that can minimize nausea and vomiting in the PACU. The treatment of this problem, once it occurs in the PACU, has not received as much study. Yet, there are a variety of drugs that are effective in treating the problem. The 5-HT3 antagonists seem particularly effective. For example, in one study of children who underwent strabismus surgery and were then nauseous during the first 3 hours after recovery from anesthesia, emesis-free episodes were greater after granisetron, 40 µg/kg (88%), compared with droperidol, 50 µg/kg (63%), or metoclopramide, 0.25 mg/kg (58%).79 In adults, granisetron, 40 µg/kg; metoclopramide, 0.2 mg/kg; or hydroxyzine, 25 mg, are also effective. Dexamethasone, 8 mg, given with other antiemetics can enhance treatment of established PONV in the PACU.80
Midazolam and propofol, although more commonly used for sedation, have antiemetic effects that are longer in duration than their effects on sedation. For example, when patients in the PACU were nauseous and then received either propofol, 15 mg, or midazolam, 1 or 2 mg, subsequent nausea was no different than with ondansetron, 4 mg.81 Acupressure bands or acupressure stimulation in the region of the P6 acupuncture point can help reduce PONV. When a ReliefBand (Neurowave Medical Technologies,™ Chicago, IL) acustimulation device was compared with ondansetron for patients who were nauseous in the PACU after receiving metoclopramide or droperidol and undergoing laparoscopic surgery, nausea was most effectively treated with both the ReliefBand and ondansetron, although both therapies were equally effective individually in treating PONV.82 If patients have already received ondansetron prophylaxis in the OR, and then are nauseous in the PACU, another repeat dose might not be effective. Based on a retrospective analysis of patients with nausea after receiving prophylactic ondansetron, established PONV was more effectively treated with promethazine than ondansetron; and promethazine, 6.25 mg intravenously, rather than higher doses was most effective.83 More work is obviously needed to study effective therapies for treatment PONV in the PACU. Finally, because pain may be associated with nausea, treatment of pain frequently decreases nausea.
Pain
Postsurgical pain must be treated quickly and effectively. It is important for the practitioner to differentiate postsurgical pain from the discomfort of hypoxemia, hypercapnia, or a full bladder. Medications for pain control should be given in small intravenous doses (e.g., 1 to 3 mg/70 kg morphine or 10 to 25 µg/70 kg fentanyl). Intramuscular injection of opioid for pain control in the PACU is probably not necessary. Onset of action of drugs is faster after intravenous catheter administration than after oral administration. Control of postoperative pain may include administration of opioid analgesics or NSAIDs, which are not associated with respiratory depression, nausea, or vomiting. Fentanyl is the narcotic frequently used to control postoperative pain that ambulatory surgery patients experience, although the effects of morphine last longer. Patients who receive fentanyl for pain control may require additional injections and go home no sooner compared with patients who receive morphine. Nonsteroidal medications, such as ketorolac or ibuprofen, can also effectively control postoperative pain and, compared with narcotics, can give pain relief for a longer period and are associated with less nausea and vomiting. NSAIDs can increase bleeding, although there is no evidence at this time of such a danger for most ambulatory surgery procedures. When swelling and pain are problematic postoperatively, NSAIDs can be more effective than opioids in relieving both.
We manage pain in both adults and children initially either with a short-acting opioid analgesic such as fentanyl (25 µg/ 70 kg), or with an injection of ketorolac, 30 to 60 mg/70 kg intramuscularly or intravenously. Fentanyl is repeated at 5-minute intervals until pain is controlled. For children, we also use an elixir of acetaminophen containing codeine (120 mg acetaminophen and 12 mg codeine, in each 5 mL of solution). Five milliliters is administered to children between the ages of 3 and 6, and 10 mL to children between the ages of 7 and 12. Children are returned to parental care as soon as they are awake. We find frequently that infants younger than 6 months of age usually need to be reunited with their mothers for nursing or bottle feeding after a procedure not associated with severe pain. For older infants and young children in the PACU, acetaminophen, 60 mg per year of age (given orally or rectally), is commonly used to relieve mild pain. Intravenous fentanyl (up to a dose of 2 µg/kg) is preferred for more severe pain. Meperidine (0.5 mg/kg) and codeine (1 to 1.5 mg/kg) can be given intramuscularly if an intravenous route has not been established.
Preparation for Discharging the Patient
In addition to the PACU, many ambulatory surgery centers in the United States have another area, often known as a phase II recovery room, where patients may stay until they are able to tolerate liquids, walk, and/or void. With the anesthetics that are typically used in ambulatory surgery ORs, patients who are awakened in the OR and are evaluated as 9 or 10 according to the modified Aldrete scoring system may be transferred directly to phase II recovery from the OR. Patients who undergo procedures under monitored anesthesia care can usually go straight to the phase II area from the OR. After general anesthesia, LMA use and pain control using nonopioid analgesics facilitates fast-tracking. In one study, 35 to 53% of patients who underwent laparoscopic gynecologic surgery were able to bypass the PACU.84 In that study, residual sedation was the most common reason the PACU was not bypassed. In another study of patients who underwent outpatient knee surgery bypassed the PACU and were in the phase II recovery area, 31% required nursing interventions and were 3 times more likely to need a nursing intervention, compared with 16% who required a nursing intervention who first went to the PACU. Yet, discharge times were faster and unplanned hospital admissions were fewer if patients were able to bypass the PACU.85 In a similar study, those authors found that even though direct transfer to phase II recovery may decrease time spent in the hospital, nursing workload was no different than if patients first went to phase I recovery.86
Some criteria for discharge to home were created without scientific basis. One criterion is the ability to tolerate liquids before being discharged. Postoperative nausea may be greater if patients are required to drink liquids prior to discharge. Even though it is warranted after spinal or epidural anesthesia, the requirement that low-risk patients void before discharge may only lengthen stay in the hospital, particularly if patients are willing to return to a medical facility if they are unable to void. Practical criteria for patient discharge from the OR, from the PACU, and from the phase II recovery area are needed that in no way compromise patient safety. The value of psychomotor tests to measure different phases of recovery (except for research purposes) is questionable.
Although scoring systems may be used to guide transfer from the PACU to the phase II recovery room and from phase II recovery to home, they do little to test higher levels of function, such as the ability to use one's hands, to drive a car, or to remain alert long enough to drive. Patients may feel fine after they leave the hospital, but they should be advised against driving for at least 24 hours after a procedure. Patients and responsible parties should be reminded that the patient should not operate power tools or be involved in major business decisions for up to 24 hours. Once the patient leaves the medical facility, supervision may not be as good as it was in the hospital. Therefore, before a patient is discharged, dressings should be checked. It is wise to include the responsible person in all discharge instructions, which are best made available on printed forms.
Patients should also be informed that they may experience pain, headache, nausea, vomiting, or dizziness and, if succinylcholine was used, muscle aches and pains apart from the incision for at least 24 hours. A patient will be less stressed if the described symptoms are expected in the course of a normal recovery. Written instructions are important. The addition of written and oral education techniques at discharge has a significant impact on improving compliance.
For patients with a language barrier (e.g., in a population with a high percentage of immigrants), consent forms, procedural explanation, and discharge information may have to be written in languages other than English and the services of an interpreter may be necessary. Nursing staff should assess the adult who will take the patient home to determine whether he or she is a responsible person. A responsible person is someone who is physically and intellectually able to take care of the patient at home. Facilities should develop a method of follow-up after the patient has been discharged. At some facilities, staff members telephone the patient the next day to determine the progress of recovery; others use follow-up postcards.
Whenever we become innovative in the management of our outpatients, we must assess how a cost-effective, “no frills” approach to care affects patient safety. We must determine what we can do for the patient who lives alone, for the patient whose responsible person is unable to manage his or her needs, for the patient without means of transportation, and for the patient with limited insurance coverage. Hospital beds can be set aside for patients who require observation. Patients in these beds after an ambulatory surgical procedure are still considered outpatients. They are charged for the hours spent in the observation area. Some hospitals have joined with management firms to build a hospital hotel or medical motel close to the hospital itself. The hotel, usually a nonmedical facility, offers the outpatient a comfortable, inexpensive, and convenient place to recuperate while being cared for by family or nurses. Home health care nursing may be appropriate after surgical procedures such as reduction mammoplasty, abdominoplasty, vaginal hysterectomy, and major open ligament repairs of the knee. The various services for management and/or observation of outpatients after surgery stand today where techniques for management of outpatients during surgery stood in the health care delivery system 20 years ago. Prospective studies are needed to assess the quality of care and the effect that these innovative approaches have on patient safety.
Patient, procedure, availability and quality of aftercare, and anesthetic technique must be individually and collectively assessed to determine acceptability for ambulatory surgery. A delicate balance must be maintained between the physical status of the patient, the proposed surgical procedure, and the appropriate anesthetic technique, to which must be added the expertise level of the anesthesiologist caring for a patient.
Anesthesia for ambulatory surgery is a rapidly evolving specialty. Patients who were once believed to be unsuitable for ambulatory surgery are now considered to be appropriate candidates. Operations once believed unsuitable for outpatients are now routinely performed in the morning so patients can be discharged in the afternoon or evening. The appropriate anesthetic management before these patients come to the OR, during their operation, and then afterward is the key to success. The availability of both shorter-acting anesthetics and longer-acting analgesics and antiemetics enables us to care for patients in ambulatory centers effectively.
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