RECOVERY AND DISCHARGE

AMBULATORY ANESTHESIA

0889-8537/96 $0.00

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20

RECOVERY AND DISCHARGE Suzanne E. Rapp, MD

The quality and speed of recovery from anesthesia and surgery are a reflection of the anesthetic management of the patient as well as the type and duration of surgery and inherent characteristics of the patient involved. The recovery process is also influenced by the skills and procedures employed by those overseeing care of the patient during recovery. This article focuses on the procedural aspects of recovery and individual factors that contribute to making a smooth transition from the operating room to home.55,81 GUIDELINES

Standard guidelines for recovery from all types of anesthesia and surgery were established in the 1970s, notably by Aldrete2and Steward.” Since that time modifications have been made to provide guidelines specifically relevant to ambulatory surgery.’2 In 1990, discharge standards for outpatient surgery were published by the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) with the help of an advisory committee comprised in part of anesthesiologists. Of particular concern was the requirement that patients be discharged by the anesthesiologist responsible for delivery of anesthesia. Following formulation of standards, the American Society of Anesthesiologists (ASA) and the Society for Ambulatory Anesthesia (SAMBA) were allowed to provide comments. The JCAHO Guidelines were then modified to permit delegation of the task of ”discharge” to qualified personnel providing that established criteria for discharge were applied. These guidelines provided a framework for institutions developing a practical checklist to be completed prior to a patient’s discharge. The fundamental provisos stipulated by JCAHO included the following: (1) a licensed practitioner must be immediately available in the facility to provide emergency care, (2) specific discharge criteria must be formulated and approved by the medical staff, (3) these discharge criteria be applied by the physician

From the Department of Anesthesiology, University of Washington School of Medicine; and the Multidisciplinary Pain Center, University of Washington Medical Center, Seattle, Washington

ANESTHESIOLOGY CLINICS OF NORTH AMERICA VOLUME 14 NUMBER 4 * DECEMBER 1996

817

818

RAPP

responsible for the patient (or their designee), (4) the name of the responsible physician must be identified on the chart, (5) the patient must be provided written instructions, and (6) the patient be discharged into the company of a responsible adult capable of assisting the patient.39The JCAHO guidelines allow for great latitude by practitioners; however, serious consideration must be given to the formulation of institutional discharge criteria that must then be rigorously applied. Griffith,3I an attorney, takes a strong stand with respect to adhering to discharge criteria. “Departures from established criteria are just invitations to the courthouse,” he voices. He emphasizes that criteria be formulated based on medical data and provision of patient safety. Deviations from the standard may place both patients and healthcare providers at risk.31 RECOVERY

Recovery from outpatient anesthesia includes dissipation of anesthetic agents, normalization of physiological functioning, observation for medical or surgical complications, treatment of immediate side effects of anesthesia and surgery, and ultimately, discharge home. It is recommended that patients recovering from ambulatory surgery be followed in two separate post anesthesia care units (PACU), traditionally referred to as phase I and phase I1 recovery.79Formal guidelines require only “a post anesthesia area.” Early or phase I recovery consists of emergence from anesthesia including recovery of protective airway reflexes and stabilization of cardiopulmonary status. Prior to transfer to a phase I1 unit, patients should be able to maintain an adequate airway and oxyhemoglobin saturation, be oriented and able to communicate, and pain and emesis should be reasonably controlled. Select patients who have undergone local or regional anesthesia with minimal or no sedation or general anesthesia with short-acting agents who are conversant, mobile, and physiologically stable, requiring minimal monitoring, may be able to bypass phase I. Institutions should formulate specific guidelines for these patients to minimize unnecessary time in phase I. Phase I1 recovery is the period during which coordination and the ability to ambulate independently occur together with further improvement in mental acuity. Typically, patients have been required to drink fluid without vomiting, and void prior to discharge. Patients are then judged “fit for discharge“ and ready to go home in the care of a responsible adult. Discharge medications (or prescriptions) are obtained and written and oral instructions provided to the patient (and their escort) when ready for discharge. The final phase of recovery, which constitutes return of fine psychomotor skills, occurs hours or days after cessation of anesthesia. Assessment by psychomotor test batteries or real driving tests are not practical in the ambulatory surgery setting.”2From volunteer studies, it can be anticipated that for a short anesthetic (< 2 hours) psychomotor and cognitive impairment persists for at least 10 to 12 hours,’2 with the anticipation of longer recovery for longer anesthetics. Therefore, the recommendation has evolved that patients should not sign important documents, make serious life decisions, or drive for 24 to 48 hours postoperatively. After local anesthesia alone (without sedation) a lesser period of restriction (i.e., 2 hours after lidocaine anesthesia) may be acceptable. Whenever possible, patients are telephoned at home on the first postoperative day to identify symptoms or complications that may require intervention. This is also a valuable tool for assessing quality of care and patient satisfaction.

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RECOVERY SCORING SYSTEMS

A scoring system must be practical, easy, and reliably indicate progressive recovery from all types of anesthetics. An early postanesthetic recovery score (PARS) was proposed by Aldrete and Kroulik whereby numeric values from 1 to 3 were assigned to five attributes similar to the Apgar Score that could readily be observed during recovery.2A score of 8 to 10 indicated adequacy of phase I recovery. The systems of both S t e ~ a r d and '~ represent similar numeric grading systems; however, all of these scales are directed at phase I recovery. The greater challenge has been to provide a scoring system that ensures a safe and comfortable trip to the homecare setting. With this goal in mind, Chung developed the Post-Anesthesia Discharge Scoring System (PADSS) for phase I1 recovery?" Although similar in concept to the Aldrete scoring system, an acceptable discharge score is now higher at 9 to 10. Chung subsequently modified the original PADSS, basically eliminating reference to fluid intake and the need to void and establish separate categories for control of pain and emesis (Table 1).l2 The modified PADSS is reasonably complete as long as the JCAHO requirement for discharge in the care of a "responsible person" is adhered to and an adequate home support system exists. Some record of having provided written guidelines to patients, including a no driving proviso, who to call for assistance, understanding of the need for accompaniment home, and availability of help at home should be signed by the patient with a copy for the medical record. To help prevent unnecessary and irritating cancellations, Ogg suggested in 1972 that several of these items appear on the operative consent (no driving, need for a ride home).5MIn current day practice, these requirements should be clearly communicated to the patient at the time of the pre-operation visit in advance of surgery. TREATMENT OF COMMON RECOVERY SYMPTOMS

The need for recovery of cardiovascular, respiratory, and neurologic functions are appreciated by all practitioners and not peculiar to ambulatory anestheTable 1. MODIFIED POST-ANESTHESIA DISCHARGE SCORING SYSTEM Vital Signs

Ambulation and Mental Status

Nausea and Vomiting

Pain

Surgical Bleeding

2 1 0 2 1 0 2 1 0 2 1 0 2 1 0

= = =

Within 20% of preoperative value 20% to 40% of preoperative value 40% of preoperative value

= = =

With assistance

= =

= = = = = = =

Steady gaitho dizziness None/dizziness Minimal Moderate Severe Minimal Moderate Severe Minimal Moderate Severe

Maximum total score is 10. Patients scoring 9 or 10 are considered fit for discharge home. From Chung F: Are discharge criteria changing? J Clin Anesth 5665, 1993; 0 1993 Elsevier Science, with permission.

sia. The following discussion relates primarily to problems that commonly complicate recovery after outpatient surgery and may result in significant delay of discharge or unplanned admission. In a recent survey at the author's institution the most common causes of delayed discharge from phase I and phase I1 recovery were identified. Not surprisingly, persistent drowsiness was the most common medical cause cited for prolonged phase I recovery (> 45 minutes) followed by uncontrolled pain and emetic symptoms. Similarly, uncontrolled pain and emetic symptoms were the most common medical causes of prolonged phase I1 recovery (> 60 minutes) followed by inability to void. Clearly, efforts to improve speed and quality of recovery should be focused on preventing and treating pain and emetic symptoms and selecting anesthetic agents that are least likely to cause prolonged drowsiness or nausea. A discussion of anesthetic techniques designed to promote rapid emergence and recovery of mental function is beyond the scope of this review. A variety of newer anesthetic agents exist (desflurane, sevoflurane, propofol, short-acting opioids) that are known to be associated with rapid recovery. At least equally important, however, is the management of postoperative pain and emetic symptoms. PAIN

Pain has historically been undertreated. Inadequate pain control has been estimated to affect about 75% of patients undergoing abdominal surgery.14A similar incidence of "undertreatment" of pain has been reported among outpat i e n t ~It. ~is~important to effectively treat pain because inadequate pain relief is not only a negative patient experience but also can result in increased health care use after discharge from the ambulatory surgery center.2h Postoperative pain is caused by stimulation of somatic visceral and neurogenic afferent nerve endings, resulting from tissue damage and inflammation. The neuroanatomy, neurophysiology and chemistry of pain are detailed elsewhere?, 5, lo Recently there has been great interest in the phenomenon of "preemptive analgesia," which theoretically might minimize or prevent postoperative pain. Animal models have demonstrated that brief, well-localized chemical, heat, or mechanical stimuli produce long-lasting neuronal sensitization (increased traffic in spinothalamic tract neurons).**,42, 72 This sensitization has been prevented by pre-injury administration of local anesthesia or ~pioids.'~, 21 A state of activitydependent enhanced responsiveness of dorsal horn neurons ("wind-up") is provoked by noxious afferent stimulation.8z,83 Therefore, it has been proposed that preemptive analgesia via local or regional anesthesia or opioids may reduce postoperative pain more effectively than postoperative medication administered after "the With the basic concept demonstrated in animals, numerous clinical studies have been reported relating to this phenomenon. Many are methodologically flawed in not comparing prophylactic with postsurgical treatments. In general, the results have been somewhat confusing, often contradictory, and the success of preemptive analgesia for postoperative pain remains somewhat controversial. A related concept that has attained recent prominence is the use of a "multimodal" approach to treat (or prevent) postoperative pain. This approach combines the use of several modalities, most commonly use of local anesthetics, anti-inflammatory drugs, and opioids, to achieve pain control.

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Local Anesthetics

A variety of avenues exist for using local anesthetics to promote postoperative analgesia (Table 2). Local wound infiltration, intraperitoneal, intrapleural, or intra-articular installation of local anesthetic, and nerve blocks of extremities (wrist blocks, ankle blocks, digital blocks, penile blocks, ilioinguinal and hypogastric blocks, and pudendal blocks) have all been advocated and demonstrated to be effective in reducing pain in the immediate postoperative period. This type of treatment can be employed preemptively (i.e., before surgery) or at the end of a procedure, and is an excellent method of reducing requirements for opioids or other analgesics, thereby minimizing side effects related to analgesic use. Use of this mode of therapy should be considered whenever it is feasible or practical to do so; however, patients must be made aware that resolution of the block may be associated with a rather abrupt increase in analgesic requirement. Nonsteroidal Anti-inflammatory Analgesics

Nonsteroidal anti-inflammatory drugs (NSAIDs) are a rational analgesic choice postoperatively because of the anticipated inflammatory response to surgery. The potential benefits include decreased inflammation secondary to inhibition of the cyclooxygenase system and hence prostaglandin synthesis, decreased synthesis of inflammatory mediators, such as bradykinin, substance P, serotonin, and histamine in the peripheral tissues as well as some central analgesic action, and the reduction of troublesome symptoms related to opioid administration, such as nausea, vomiting, sedation, and urinary retention.I7 Preoperative NSAID administration has clearly been shown to decrease opioid requirements in the immediate postoperative period and improve patient comfort on initial awakeningz7,34, 68 The added benefit of preoperative versus postoperative administration in the ambulatory surgery setting may be to have a more comfortable patient immediately postoperatively who may then require only oral medications to control their pain. Although preoperative NSAIDs may lower opioid requirements, postoperative pain scores do not necessarily differ whether administrated pre- or postoperatively as demonstrated by Dunn in outpatient laparoscopy ~atients.2~ Similar findings have been reported by others, Table 2. REGIONAL BLOCKS FACILITATING POSTOPERATIVE PAIN RELIEF Ophthalmology Oralhasal surgery Upper extremity surgery Lower extremity surgery

Retrobulbar and peribulbar blocks Mandibular and intra-oral nerve blocks, local infiltration Axillary block, interscalene, wrist blocks, digital blocks, Bier block with ketorolac, 60 mgh0 mL local anesthetic Knee surgery-Femoral nerve block; intra-articular local anesthetic injection with or without morphine 1 mg/20 mL Foot surgery-Ankle blocks; transmetatarsal block Groin surgery-llioinguinal and iliohypogastric nerve blocks, field block, wound infiltration Penile surgery-Dorsal nerve penis block Pelvic surgery-Paracervical and pudendal blocks Lower abdomen-Wound infiltration, peritoneal irrigation, infiltration of mesovarium

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RAPF

leading one to question the relevance of preemptive analgesia versus simple analgesia by NSAIDs in postsurgical patients. Many NSAIDs from different chemical groups (acetic acids, proprionic acids, oxicams, fenamates, salicylates) are available from which to choose (Table 3). Rational selection of a particular NSAID is challenging because of significant interpatient variability with respect to analgesia and side effects, which may be pharmacokinetic, pharmacodynamic, or both.I8 There are several factors to be considered: relative efficacy, route of administration, dosing schedule, and side effects.6o Concurrent medications and coexisting medical problems should be taken into account when selecting an appropriate drug to avoid unwanted interaction or side effects. Only one NSAID should be used at a time. Route of Administration and Dosing Schedule

When selecting the route of administration one first considers the least invasive, most practical route. The rectal route may mitigate against gastrointestinal side effects, and although it may not be socially acceptable to the awake patient, it might be considered for preoperative administration after induction of anesthesia. Injectable NSAIDs provide more rapid absorption than the oral route and are readily administered intraoperatively before awakening. Of those tested for parenteral use, ketorolac and diclofenac provide analgesia with fewest side NSAIDs have been shown to be more effective if constant blood levels are maintained; therefore, time contingent dosing is recommended. Some medications are dosed less frequently, which may be an advantage for many patients (see Table 3). Efficacy

There are few studies comparing the plethora of NSAIDs currently available. One early arthritis study comparing fenoprofen, ibuprofen, ketoprofen, and naproxen reported fewer side effects with ibuprofen and naproxen, and recommended naproxen as being slightly more effective.36Additionally, in the author's practice of acute, chronic and cancer pain patients, naproxen has appeared superior to other NSAIDs, (e.g., easy for patients with twice-a-day dosing if the gastrointestinal (GI) side effects can be tolerated); however, it is unclear whether differences observed would also pertain to patients undergoing outpatient surgery. Unfortunately, there are few studies comparing newer agents and no large series comparing the nonacetylated salicylates, which possess fewer GI and hematologic side effects than other agents. Side Effects/Toxicity

Toxicity needs to be considered from the outset. The most significant potential adverse responses with NSAIDs concern altered coagulation, GI ulceration, inflammation or irritation, and nephrotoxicity. Of the currently available NSAIDs, most, with the exception of the nonacetylated salicylates, are associated with some minor alterations of coagulation. Thus, ketorolac in normal volunteers causes decreased platelet aggregation and prolongs bleeding time, although the bleeding time typically still remains within the normal range.8 These studies leave some room for speculation as to whether the increase in bleeding time is clinically significant.15It has been shown in hysterectomy as well as in tonsillec-

W

03 h,

Acetaminophen

Tylenol

500-750

Disalcid 325-1.000

25-75 200 500-1,000 250-500

250-500

500-750

Ketoprofen Fenoprofen Aspirin Diflusinal

Naproxen

Trilasate

25-75 1000 10 (1-0 P) 150 20 200-800

Choline Magnesium Salicylate Salsate

Voltaren Relafen Toradol

Diclofenac Nabumetone Ketorolac

200-400 150-200

Meclomen Feldene Motrin, Advil,? Rufen, Nuprin Naprosyn, Anaprox, Alevet Orudist Nalfon Anacin Dolobid

Tolectin Clinoril

Tolmetin Sulindac

25-50

Dose (mg)

Meclofenamate Piroxicam Ibuprofen

lndocin

Product Name

lndomethacin

Generic Name

4-6

12

12

6-8 4-6 4-6 8-12

12

6-8 24 4-8

6-1 2 12-24 4-6

8 12

6-8

Dosing Interval (hr)

1

2

2

0.5-2 1-2 0.5 2

1

1-15 5.5 0.5

1-3 4 1-1.5

1-2 0.5-1

1-2

Onset (hr)

PO, P'

PO

PO

PO PO PO, Pr PO

PO

PO PO PO

PO PO PO

PO PO

PO, P'

Route

'Cost is per lowesl dose pill pharmacy acquisition cost; there is usually an additional institutional cost in prescribing tAvailable over the counter. GI = gastrointestinal; im = intramuscular; PO = per orum; pr = per rectum; PMS = premenstrual syndrome.

P-aminophenol derivative

Salicylates Nonacetylated salicylates

Fenamate Oxicam Proprionic acids

Acetic aids

Chemical Class

Table 3. NONOPlOlD ANALGESICS

Minimal GI; no platelet toxicity Usually well tolerated

Minimal GI; no platelet toxicity Minimal GI; no platelet toxicity

GI, platelet, renal GI, platelet, renal

GI, platelet, renal

GI, platelet, renal GI, platelet GI, platelet, renal

GI, platelet, renal Low GI toxicity GI, platelet, renal

GI, platelet, renal GI platelet

GI, platelet, renal

Main Side Effects

$0.01

$0.04

$0.50

$0.32 $0.16 $0.01 $0.31

$0.08

$0.43 $0.78 $0.99 PO $7.0 im $0.11 $0.17 $0.02

$0.02 PO $1.33 pr $0.55 $0.10

Cost'

Overdose produces hepatic toxicity

Available in liquid

Not antipyretic

May have additional central site of action

Used in PMS Available in liquid

High GI irritability

Less renal toxicity than most; used for renal colic

Other Attributes

tomy patients that blood loss increases after preoperative ketorolac70; however, in patients undergoing knee arthroscopy, thromboxane B, was markedly reduced, but bleeding time, platelet aggregometry, and thromboelastography were unchanged 45 minutes after ketorolac admini~tration.~~ Thus, the significance of altered coagulation remains controversial and must be evaluated by surgical procedure or on an individual basis. It may be prudent in some instances to delay treatment with NSAIDs until after surgery, when normal coagulation mechanisms have had a chance to be effective. GI irritation with nausea, vomiting, or diarrhea occurs relatively commonly with most NSAIDs, but they appear to be better tolerated than opioids. Serious problems, such as ulceration, occur less commonly and most likely occur with chronic use. With regard to continued administration after surgery, Kehlet and Dah141reported in a meta-analysis of gastrointestinal complications from NSAIDs that there was no increase in incidence of serious complications in the first week of treatment. GI protection by antacids or H, blockers may be warranted for continued use but have not been studied for short-term use in postoperative outpatients. Many NSAIDs, as well as aspirin, are known to affect prostaglandin synthesis and may diminish renal blood flow. Significant effects on renal function have generally occurred only in the setting of prolonged use; however, prudence would suggest avoiding these drugs where renal blood flow may be compromised. Therefore, although there is significant potential advantage of pre- or postoperative NSAID use in ambulatory surgical patients, such as improved analgesia upon awakening, a well-documented decreased opioid requirement, and a potential decrease in opioid side effects, this must be weighed against the risk of increased bleeding that might be expected to vary among surgical procedures. NSAIDs are indicated for mild postoperative pain but should be considered as adjuvants for moderate to severe postoperative pain when opioids are indicated. There are limited studies assessing the efficacy among NSAIDs. Opioids

Intravenous opioids remain the mainstay for treatment of postoperative pain. Generally, agents of short duration (i.e., fentanyl) are preferred in efforts to reduce prolonged sedation, as may occur with morphine and other longacting opioids; however, use of drugs of intermediate duration (i.e., meperidine) may be advantageous in attaining sustained control of pain initially.37Meperidine has the added benefit of decreasing shivering upon anesthetic emergence. When able, patients should be switched to oral medication and, if possible, adequacy of pain relief judged before discharge (this may not be possible for patients discharged with persistent nerve blocks). In general, mixed agonist/ antagonists, such as nalbuphine and pentazocine, have been associated with greater sedation relative to analgesia when compared to traditional opioids, and do not appear to be particularly advantageous for outpatients. Opioids commonly administered orally may include (in order of potency) codeine, meperidine, hydrocodone, and oxycodone (Table 4). They are usually prescribed to be taken 1 to 2 tablets every 4 to 6 hours and in combination with acetaminophen. For patients sensitive to these agents, oral hydromorphone (Dilaudid) or morphine may be prescribed. The peak levels of these medications are achieved at 2.5 to 3.5 hours, so to achieve adequate analgesia one might need dosing every 3 Larger opioid requirements may be anticipated in

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Table 4. ORAL OPlOlD EQUIVALENTS Drug Name

Short Acting* Codeinett Hydrocodone*§ Hydromorphone (dilaudid) Meperidine (dernerol) Morphine Oxycodonell Propoxyphenetll (darvon) Tramadol (ultrarn) Long Acting Methadone (dolophine, others) Morphine

Equivalent Doses

Dosing Interval (hrs)

Starting Doses (adults)

4-6 4-6 4-6

30-60 rng 5-10 rng 1-2 rng

300 mg

4-6

50-100 rng

10-30 mg 30 rng 520 rng

4-6 4-6 4-6

10-30 mg 5-10 rng 65-130 rng

4-6

50-100 mg

10 rng

6-8

5-10 rng

60 rng

8

15-30 mg

200 rng

30 rng 7.5 rng

500 rng**

'Above short-acting medication doses equivalent to 10 mg parenteral morphine. Most of these medications are available or can be formulated in liquid form. tAvailable in combination with Tylenol as Tylenol 111. *May be ordered by telephone. §Available in combination with Tylenol as vicodin, lorcet, zydone, bancap, and with aspirin as adzine. IlAvailable in combination with Tylenol as percocet, tylox, roxicodone, and with aspirin as percodan. (Available in combination with acetaminophen (darvocet) and aspiridcaffeine (Darvon Compound

65). "Approximate dose-equivalent based on clinical experience.

patients with prior opioid use.@Meperidine is the only opioid with significant toxicity caused by accumulation of normeperidine, which has a tl,* of 12 hours and may lead to seizures.37To minimize nausea, oral medications should be provided with small sips of liquid and biscuits. If a patient is uncomfortable after the initial dose of oral opioids and is opioid tolerant, the first strategy should be to add a third tablet immediately, before changing agents or reverting to intravenous administration. The author's surgical staff typically prescribe these medications and may require some on-the-spot tutoring to ensure patient comfort. Tramadol is a new analgesic that is somewhat unique in that it combines both opioid and nonopioid mechanisms of analgesia. It is of approximately equal potency to m e ~ e r i d i n e ~ it ~has ; not yet been extensively studied in the ambulatory surgery population. It has been used in Germany since 1977, and is currently available in approximately 70 countries. It has weak agonist activity at all types of opioid receptors with some selectivity for the mu Nonopioid mechanisms of action, although not fully understood, include inhibition of neuronal noradrenaline uptake and serotonin release.23Although side effects are similar to those of pure opioids, there is some data to suggest they may be less severe.35,38, 65 Tramadol has been used epidurally in patient-controlled analgesia pumps and compared to morphine in patients after major It is available for use in both oral and parenteral form in Europe, but only orally in the United States. Based on a review of the literature, tramadol

may be relied upon to provide relief for mild to moderate but not severe pain; 75 this is the type of pain expected among most ambulatory surgery Tramadol is not recommended as an adjunct to anesthesia as its use has been reported to be associated with an increased incidence of intraoperative awareness not shown with other analgesics.47,50 Perineural, plexus, and intra-articular opioid injections have been tested in an attempt to improve and prolong analgesia. Morphine and meperidine have been injected intra-articularly after knee arthroscopy with variable Meperidine, when compared with morphine, provided early but not sustained a n a l g e ~ i aMost . ~ ~ studies revealed an immediate decrease in opioid requirement with the longest analgesia when bupivacaine was included in the i n j e ~ t a t e . ~ ~ Factors important in intra-articular injection include using an adequate opioid to saturate or bind to all local receptors but avoid a systemic effect, and long enough tourniquet time (10 minutes) to avoid hyperkinetic blood flow in the articular region, resulting in a washout effect. It is unclear at this point whether the volume of injectate alters effecti~eness.~~ Low-dose morphine (1mg) has also been added to brachial plexus blocks without significant benefit.25,28 In larger doses (0.1 mg/kg) a decrease in 24-hour pain medication requirement has been demonstrated in that model7;however, in none of these studies was the presence or absence of inflammation noted, which is important because the presence of inflammation favors the expression of peripheral opioid receptors.61It is also uncertain at what dose systemic effects begin to contribute to the effect. Outcome in terms of earlier discharge has not been assessed. Other injectate additives have been studied. Intravenous regional anesthesia with ketorolac, but not meperidine, as part of the injectate decreased tourniquet pain and enhanced postoperative analgesia both in PACU and at home.', hh Steroid added to ilioinguinal nerve block did not improve analgesia.54 There is reluctance to add opioids to conductive anesthesia because of the risk of delayed respiratory depression. The addition of fentanyl to lidocaine subarachnoid block prolongs sensory block to the same extent as epinephrine,5I but without prolongation of motor block as occurs with epinephrine. Delayed effects may be anticipated with morphine but are less prominent with more lipophilic agents.16 To date, use of intrathecal or epidural morphine are not recommended in outpatients for pain control. Fentanyl may be an acceptable drug because of its short duration of action.

POSTOPERATIVE NAUSEA AND VOMITING

Contributing factors for nausea and vomiting include female gender, pain, anesthetic agents, analgesic agents, sudden movement or position change, pain, history of post-surgical nausea, history of motion sickness, hypotension, menstrual cycle variables, type of surgery, and obesity.8O Postoperative nausea and vomiting (POW) continues to be cited as one of the most important factors in determining home readiness and unanticipated admission following ambulatory surgery. These symptoms are also distressing to patients and result in morbidity and inability to work after discharge? Propofol's antiemetic properties have been demonstrated alone in short cases (< 30 minutes) when used for induction and when used in moderate supplemental doses as compared with isoflurane and desflurane.6,30 It has also been demonstrated to prevent opioid-induced emetic symptoms when infused at low rates (in sedative doses) both during and for several hours after termina-

RECOVERY AND DISCHARGE

827

tion of infusion.62Therefore, in susceptible patients, low-dose intraoperative propofol infusion may be of some benefit. The ideal antiemetic agent, one which provides universal prophylaxis or treatment with minimal side effects, has yet to be identified. It is also unclear as to when is the best time to administer antiemetics, although numerous studies are now suggesting that prophylactic administration can be of benefit in susceptible patient^.'^ A list of common antiemetics and their mechanism of action is found in Table 5. If one elects not to treat prophylactically, then criteria as to when to treat need to be established (i.e., first mention of symptom, persistence longer than 10 minutes, etc.). A variety of categories of antiemetics exist, and within each category several different drugs are available, with various advantages and disadvantages. Of the dopamine inhibitors, droperidol has been shown to cause restlessness and anxiety (dysphoria) in up to 23% of patients when administered preoperatively in the absence of other drugs. This appears to be less common with metaclopramide. Droperidol may also cause temporary sedation. Both droperidol and metaclopramide may rarely cause extrapyramidal symptoms (EPS), particularly in patients known to develop EPS with phenothiazines. In contrast, ondansetron (and presumably other serotonin inhibitors) appears to be equally if not more effective than either of the commonly used dopamine antagonists, and is relatively free of undesirable side effects. It is, however, considerably more expensive (approximately $0.48 for droperidol, 2.5 mg versus $17.00 for ondansetron, 4 mg [pharmacy acquisition charges]). Ephedrine, a sympathomimetic, given 0.5 mg/ kg intramuscularly (im), has been shown in one study to be as equally effective as droperidol and may be useful in young healthy patients, particularly females.69Ephedrine is a central Table 5. COMMON ANTIEMETICS ~

Drug Name Droperidol (inapsine) Metaclopramide (reglan) Ephedrine

Site of Action

6

CTZt

Dizziness

Dopaminergic

10-20 wglkg . - . iv or im 10 mg iv or PO

6

Dystonia

Sympathomimetic

0.5 mglkg im or

4

5-HT, CTZt CTZt .1 vagal tone V*

Category of Drug Dopaminergic

Dose

5-10 rng iv

Scopalamine

Anticholinergic

Ondansetron (zofran)

H, serotonin

Hydroxyzine (vistaril) Prochlorperazine (compazine)

Antihistamine*

Promethazine (phenergan)

~~~~

Duration (hrs)

inhibitor

Phenothiazine, antihistamine, anticholinergic Phenothiazine, anticholinergic, antihistamine

0.5 mg transdermally (behind mastoid) 4-8 mg iv; 8 mg PO

50-100 mg im; 25-50 mg PO 5-10 mg im or PO; 2.5-10 rng iv; 25 mg PR 12.5-25 mg PO, im, iv, pr

72

4-6 6

ToxicityISide Effects

Hypotension Confusion, blurred vision

GI tract Headache 5-HT3 receptor CTZt Drowsiness

4-6 12 (PR)

CTZt

EPS Drowsiness

4-6

VS

EPS Drowsiness

*Antihistamines are often used in combination with phenothiazines for improved efficacy and minimization of EPS. tchemotactic trigger zone $Vomiting center

828

RAPP

stimulant, and in some patients appears to also cause increased alertness, which may be beneficial. Scopolamine, an anticholinergic, has been demonstrated to be effective when applied in transdermal form (scopolamine patch, 1.5 mg, releases 5 Fg/hour for 72 hours). It requires 4 to 6 hours for peak effect and is most useful when applied before surgery, but can be applied postoperatively and be expected to provide sustained effect after discharge; however, it does cause visual blurring in 20% of patients and occasionally confusion, especially in children or the elderly. Therefore, it is currently not recommended for patients less than 12 or older than 60 years old. Antihistamines, although relatively effective antiemetics, are often associated with drowsiness, which has tended to limit their use in ambulatory surgery. Phenothiazines, although advantageous because they potentially affect several different types of receptors believed to mediate nausea, also have been avoided as first-line drugs because of the general tendency to cause sedation as well as EPS; however, a recent study has suggested that perphenazine was equally or more effective than either droperidol or ondansetron without causing any detectable ~edati0n.l~ Clearly, more studies are required to test the relative efficacy of various antiemetics weighed against relative cost. Although prophylactic antiemetics in selected high-risk patients may improve quality of patient recovery, Dexter and Tinkerz0predicted on the basis of a computer-simulated study that antiemetics would not decrease recovery room costs. In a capitated medical system cost certainly increases when overnight admission due to nausea and vomiting is required; however, due to the significant proportion of PACU costs that are related to cost of personnel, PACU costs might not significantly decrease if all P O W was prevented. Nevertheless, quality of recovery is a significant goal and should not be neglected in the current quest for cost ~ o n t a i n m e n t . ~ ~ UNANTICIPATED ADMISSIONS Hospital admission following outpatient surgery is an undesirable outcome. Admissions are disruptive to patients' lives, the smooth operation of the surgical center, and now carry increasingly punitive fiscal considerations due to stringent insurance reimbursement policies, managed care, and capitation. Although 50% of surgeries are now performed in US hospitals on an outpatient basis, there has been no change over time in the rate of unanticipated admissions (o.090/0-16~~)."5, 29, The variation in rates undoubtedly reflect different institutions, patient selection, and types of surgeries performed. A review of studies evaluating causes of unplanned admissions finds marked similarities over time: uncontrolled P O W and pain are the most frequent anesthetic-related cause of admission, extensive procedures have a propensity to lead to admission, and surgical issues are the most common cause of admission (Table 6). Indeed, Wetchler cites a review of 32,010 patients, noting that 75% of patients were admitted for surgical issues.79Anesthesia admissions accounted for 18%, with social admissions accounting for approximately 6%. An important issue is whether many "unplanned admissions" could be avoided through better planning preoperatively, or alternatively by improved care during and after anesthesia and surgery. In a study of "unplanned admissions" Twersky et aln reported that 58% of admissions were unavoidable, 23% potentially avoidable, and 16% avoidable. Their analysis included admissions for surgical, medical, and anesthetic cornpli~ations.~~

m

10.000

9616

10,000

39.654

2160

2268 236

3340

18,321

2470

2039

7

8

9

11

12

13 14

15

21

22

28 5.00%

3.60%

1.20%

0.50%

1.30% 2.10%

1.60%

1.10%

0.70%

1.OO%

0.90%

9.50% 0.28%

Admission Rates

Extensive surgery; hemorrhage; perforated viscus Vomiting; extensive surgery; hemorrhage Vomiting; hemorrhage; postoperative pain

Extensive surgery; vomiting; drowsiness Vomiting; extensive surgery; respiratory Extensive surgery; hemorrhage; apnedbradycardia Vomiting; pain; drowsiness Extensive surgery; vitreous loss; slow awakening Hemorrhage; dehydration; emesis

Extensive surgery; dizziness; pain Bleeding; surgical complication; extensive surgery Protracted vomiting; extensive surgery; croup Pain; bleeding; vomiting

3 Most Frequent Causes for Admission

1989

1986-89

1984-90

1980-88

1985-86 NR

1982-86

1955-85

1982-87

198446

198346

1987 1977-87

Year Surveyed

Gynecological surgery only United Kingdom

Freestanding; tonsillectomy and adenoidectomy only Australia

Ophthalmic Cataract surgery

Pediatric

Pediatric

University based; adult England

Hospital based Canadian hospital based Pediatric

Comments

From Gold BS: Unanticipated admissions. In McGoldrick KE (ed): Ambulatory Anesthesiology: A Problem-oriented Approach. Baltimore, Williams & Wilkins, 1995, p 676; with permission.

4

1971 90,234

Number of Patients

1

Reference

Table 6. REASONS FOR ADMISSION

Urologic surgery was associated with a four times greater risk for admission than other types of surgery. The major reasons cited for this high admission rate was the need for catheterization (hematuria) and more extensive surgery than originally anticipated. Potentially avoidable admissions included PONV, pain, and inability to void, symptoms that may have been more optimally treated if anticipated. Avoidable admissions included extensive surgery (appropriateness for ambulatory surgery), late start in the operating room, and a few with no escort or home support. Unavoidable included primarily more extensive surgery, bleeding, and need for additional medical observation. Interestingly, neither ASA status nor age were predictors for unplanned admission.77 With the changes in healthcare reimbursement it behooves all providers to critically assess the cause of unanticipated admissions for avoidable factors, appropriateness of procedure for outpatients (e.g., longer duration/extensive procedures), and surgical scheduling during the day. It seems clear from these authors' results that an institutionally integrated approach should be in place, starting with surgical planning, scheduling, and on through to symptom treatment in recovery. Procedures known to be associated with relatively prolonged recovery might be best scheduled in the early morning. Others might be best served by "planned admission." As already described, early aggressive treatment to prevent or control pain and nausea are high priority items, both as a means of eliminating the necessity of admission and improving patient comfort. This was well demonstrated by Michaloliakou et aF6in patients undergoing outpatient laparoscopic cholecystect~my.~~

CONTROVERSIES IN DISCHARGE CRITERIA: INPUT AND OUTPUT

There are several criteria that have traditionally been considered as necessary prior to discharge after ambulatory surgery that are now undergoing revision in many institutions, in particular, the ability to tolerate oral intake and void before discharge. The concern regarding whether to force oral fluids or not relates to the desire to ensure that patients are able to tolerate oral intake; however, oral fluids may provoke vomiting in patients who are otherwise well. Schreiner7' looked at voluntary versus mandatory oral intake in children. He found no difference in the frequency of PONV or admission between the two groups, although time to discharge was greater in the mandatory drinkers. Most emetic symptoms are time limited and resolve during the first 24 to 48 hours.' Inability to void is another cause for discharge delay. Potential causes include postoperative obstruction secondary to instrumentation of the urinary system during surgery, overdistension of the bladder secondary to aggressive fluid resuscitation, catheterization, dehydration, prolonged effects of general anesthesia (particularly neuraxial blockade), and certain diseases that may be associated with autonomic dysfunction, such as diabetes. It is useful to note that certain patients are routinely catheterized intraoperatively and would be expected to have an empty bladder at termination of surgery. It may be unrealistic to expect them to void prior to discharge. It is possible to anticipate that certain groups may have trouble. A treatment plan should be developed to include expected exigencies. One-time in-and-out catheterization has been used as a strategy by some imtitutions with a follow-up number to call for problems.

RECOVERY AND DISCHARGE

831

COST CONTAINMENT

Pharmacologic costs incurred during anesthetic administrations are often targeted in cost reduction. Indeed, it has been shown that formulation of group practice guidelines can impact drug costs." 44, 52 The basis for cost reduction is physician awareness of cost as well as establishment of guidelines for the more expensive agents; however, when PACU costs are tabulated, personnel constitute greater than 95% of total cost. In a computer simulation study using current PACU costs, Dexter and Tinkerzofound the major determinant of PACU costs is the distribution of admissions. They also concluded that practically achievable decreases in discharge time would not significantly impact the peak number of patients during the day, and therefore would not alter the personnel requirements in PACU, which constitutes the major expense of recovery room care.2o,52 The establishment of value-based care focuses on a multidimensional approach to cost reduction involving the administration and all caregivers. Individual savings, although small, may achieve small but significant reductions in cost when multiplied by a large patient load. The recently introduced short-acting anesthetic agents may in the multidimensional context be better able to facilitate home readiness despite their increased cost." Similarly, various advances in treatment of pain and emetic symptoms may ultimately be demonstrated to be cost effective; however, as of yet, few definable fiscal benefits have been demonstrated from variations in anesthetic care. Clearly, one goal of future clinical research should be to critically examine how modifications of anesthetic care affect quality and duration of recovery from ambulatory surgery. Examination of cost is but one aspect of this type of analysis. It is to be hoped that optimal patient care will continue to be the foremost concern in determining therapy. References 1. Acalovschi I, Cristea T: Intravenous regional anesthesia with meperidine. Anesth Analg 81:539, 1995 2. Aldrete JA, Kroulik D A postanesthetic recovery score. Anesth Analg 49:924, 1970 3. Bastrin RD, Villamaria FJ: Use of practice parameters to control drug costs. Anesthesiology 83:A1059, 1995 4. Bonica JJ: Anatomic and physiologic basis of nociception and pain. In Bonica JJ (ed): The Management of Pain, ed. 2. Philadelphia, Lea & Febiger, 1990, p 28 5. Bonica JJ, Yaksh TL, Liebeskind JC, et al: Biochemistry and modulation of nociception and pain. In Bonica JJ (ed): The Management of Pain, ed. 2. Philadelphia, Lea & Febiger, 1990, p 95 6. Borgeat A, Wilder-Smith SHG, Saian M, et al: Subhypnotic doses of propofol possess direct antiemetic properties. Anesth Analg 74:539, 1992 7. Bourke DL, Furman WR Improved postoperative analgesia with morphine added to axillary block solution. J Clin Anesth 5:114, 1993 8. Buchanan GR, Martin V, Levine PH, et al: The effects of "anti-platelet" drugs on bleeding time and platelet aggregation in normal human subjects. Am J Clin Pathol 68:355, 1977 9. Carroll NV, Miederhoff P, Cox FM, et al: Postoperative nausea and vomiting after discharge from outpatient surgery centers. Anesth Analg 80:903, 1995 10. Chapman CR, Turner JA: Psychologic and psychosocial aspects of acute pain. In Bonica JJ (ed): The Management of Pain, ed. 2. Philadelphia, Lea & Febiger, 1990, p 122 11. Chittleborough MC, Osborne GA, Ridkin GE, et al: Double-blind comparison of patient recovery after induction with propofol or thiopentone for day-case relaxant general anaesthesia. Anaesth Intensive Care 70:169, 1992

12. Chung F Are discharge criteria changing? J Clin Anesth 5:64S, 1993 13. Coderre TJ, Vaccarino AL, Melzack R Central nervous system plasticity in the tonic pain response to subcutaneous formalin injection. Brain Res 535:155, 1990 14. Cohen FL: Postsurgical pain relief: Patients’ status and nurses’ medication choices. Pain 9:265, 1980 15. Conrad KA, Fagan TC, Mackie MJ, et a1 Effects of ketorolac tromethamine on hemostasis in volunteers. Clin Pharmacol Ther 43:542, 1988 16. Cousins MJ, Mather LE: Intrathecal and epidural administration of opioids. Anesthesiology 61:276, 1984 17. Dahl JB, Kehut H: Nonsteroidal anti-inflammatory drugs: Rationale for use in severe postoperative pain. Br J Anaesth 66:703, 1991 18. Day RO, Brooks PM: Variations in response to non-steroidal anti-inflammatory drugs. Br J Clin Pharmacol 23:655, 1987 19. Desilva PHDP, Darvish AH, McDonald SM, et al: The efficacy of prophylactic ondansetron, droperidol, perphenazine, and metoclopramide in the prevention of nausea and vomiting after major gynecologic surgery. Anesth Analg 81:139, 1995 20. Dexter F, Tinker JH: Analysis of strategies to decrease postanesthesia care unit costs. Anesthesiology 8294, 1995 21. Dickinson AH, Sullivan A F Subcutaneous formalin-induced activity of dorsal horn neurones in the rat: Differential response to an intrathecal opiate administered pre- or post-formalin. Pain 30349, 1987 22. Dougherty PM, Willis WD: Enhancement of spinothalamic neuron responses to chemical and mechanical stimuli following combined micro-ion to phoretic application of N-methyl-D-aspartic acid and Substance P. Pain 4785, 1991 23. Driessen B, Reimann W: Opioid and non-opioid components independently contribute to the mechanism of action of tramadol, an “atypical” opioid analgesic. Br J Pharmacol 105147, 1992 24. Dunn TJ, Clark VA, Jones G: Preoperative oral naproxen for pain relief after day case laparoscopic sterilization. Br J Anaesth 7512, 1995 25. Flory N, Van-Gessel E, Donald F, et al: Does the addition of morphine to brachial plexus block improve analgesia after shoulder surgery? Br J Anaesth 7523, 1995 26. Ghosh S, Sallam S Patient satisfaction and postoperative demands on hospital and community services after day surgery. Br J Surg 81:1635, 1994 27. Gillies GWA, Kenny GNC, Bullingham RES, et a1 The morphine sparing effect of ketorolac tromethamine: A study of a new, parenteral non-steroidal anti-inflammatory agent after abdominal surgery. Anaesthesia 42727, 1987 28. Gobeaux D, Landais A. Utilisation de deux morphiniques dans les blocs du plexus brachial. Cah Anesthesiol 36:437, 1988 29. Gold BS Unanticipated admission. In McGoldrick KE (ed): Ambulatory Anesthesiology: A Problem-Oriented Approach. Philadelphia, Williams & Wilkins, 1995, p 670 30. Green G, Jonsson L Nausea: The most important factor determining length of stay after ambulatory anaesthesia: A comparative study of isoflurane and/or propofol techniques. Acta Anaesthesiol Scand 37742, 1993 31. Griffith JL, McLaughlin S H Legal implications. In Wetchler BV (ed): Anesthesia for Ambulatory Surgery. Philadelphia, JB Lippincott, 1985, p 33 32. Herbert M, Healy TEJ, Bourke JB, et al: Profile of recovery after general anesthesia. Br Med J 286:1539, 1983 33. Hertz CM, Glass PSA, Can TJ, et al: Nausea and vomiting: A costly anesthetic complication? Anesthesiology 83:A1036, 1995 34. Hodsman NBA, Bems J, Blyth A, et al: The morphine sparing effects of diclofenac sodium following abdominal surgery. Anaesthesia 421005, 1987 35. Houmes RJM, Voets MA, Verkaaik A, et a1 Efficacy and safety of tramadol versus morphine for moderate and severe postoperative pain with special regard to respiratory depression. Anesth Analg 74:510, 1992 36. Huskisson EC, Woolf DL, Balme H W , et a1 Four new anti-inflammatory drugs: Responses and variations. Br Med J 481048, 1976 37. Jaffee JH, Martin WR Opioid analgesics and antagonists. In Gilman A, Rall TW, Nies

RECOVERY AND DISCHARGE

833

AS, et a1 (eds): The Pharmacological Basis of Therapeutics, ed. 8. San Francisco, McGraw Hill, Inc, 1993, p 485 38. Jensen EM, Ginsberg F: Tramadol versus dextropropoxyphene in the treatment of osteoarthritis: A short term double-blind study. Drug Invest 8:211, 1994 39. Joint Commission on Accreditation for Hospitals 1990. Hospital Sponsored Ambulatory Care Services. SA 1.31, 2.1-1.32.3, p 31, 1990 40. Kallar SK, Chung F Practical application of postanesthetic discharge scoring system: PADSS. Anesthesiology 77:A12, 1992 41. Kehlet H, Dahl JB: Are perioperative nonsteroidal anti-inflammatory drugs ulcerogenic in the short term? Drugs 44(suppl 5):38, 1992 42. Kenshalo DR Jr, Leonard RB, Chung JM, et al: Responses of primate spinothalamic neurons to graded and to repeated noxious heat stimuli. J Neurophysiol42:1370, 1979 43. Khoury GF, Chen ACN, Garland DE, et al: Intra-articular morphine, bupivacaine and morphine/bupivacaine for pain control after knee videoarthroscopy. Anesthesiology 79:263, 1992 44. Kirsch M, Borra H, Ragan R Do anesthesia group practice decisions have an impact on hospital pharmacy drug costs? Anesthesiology 83:A1061, 1995 45. Lane L: Outpatient surgery trends. Ambulatory Care Trendlines, American Hospital Association, No. 1, 1992 46. Lee CR, McTavish D, Sorkin EM: Tramadol: A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential in acute and chronic pain states. Drugs 46313, 1993 47. Lehmann KA, Krauskopf K-H: Awareness during balanced anesthesia. A randomized double-blind study with fentanyl, pentazocine and ketamine. Anaesthetist 41:373, 1992 48. Lehmann KA, Horrich G, Hoeckle W: Tramadol as an intraoperative analgesic: A randomized double-blind study with placebo. Schmerz 7:146, 1986 49. Lehmann KA, Jung C, Hoekle W Tramadol and pethidine in postoperative pain therapy: A randomized double-blind trial with intravenous on-demand analgesia. Schmerz 6238, 1985 50. Lehmann KA, Kratzenberg U, Schroeder-Bark 8, et al: Postoperative patient-controlled analgesia with tramadol: Analgesic efficacy and minimum effective concentrations. Clin J Pain 6212, 1990 51. Liu S, Chiu AA, Carpenter RI, et al: Fentanyl prolongs spinal anesthesia without prolonging recovery. Anesth Analg 80:730, 1995 52. Lubarsky DA, Smith LR, Glass PSA: A comparison of maintenance drug costs of isoflurane, desflurane, sevoflurane, and propofol with OR and PACU labor costs during a 60 minute outpatient procedure. Anesthesiology 83:A1035, 1995 53. Lyons B, Lohan D, Flynn CG, et al: Intra-articular analgesia for arthroscopic meniscectomy. Br J Anaesth 75:552, 1995 54. McCleane G, Mackle E, Stirling I: The addition of triamcinolone acetonide to bupivacaine has no effect on the quality of analgesia produced by ilioinguinal nerve block. Anaesthesia 49:819, 1994 55. McGoldrick KE (ed): A Problem Oriented Approach. Philadelphia, Williams & Wilkins, 1995 56. Michaloliakou C, Chung F, Sharma S Preoperative multimodal analgesia facilitates recovery after ambulatory laparoscopic cholecystectomy. Anesth Analg 84:44, 1996 57. Niemi L, Pitkanen M, Touminen M: Intra-articular morphine for pain relief after knee arthroscopy performed under regional anaesthesia. Acta Anaesthesiol Scand 38:402, 1994 58. Ogg TW:An assessment of postoperative outpatient cases. Br Med J 4:573, 1972 59. OHara DA: Injectable nonsteroidable anti-inflammatory drugs. Anesthesiology Clinics of North America 11:815, 1993 60. Orme M: Profile of non-steroidal anti-inflammatory drugs. Prescribers Journal 30:95, 1990 61. Parsons CG, Czlonknowski A: Peripheral opioid receptors mediating antinociception in inflammation: Activation by endogenous opioids and role of the pituitary adrenal axis. Pain 41:81, 1990 62. Pavlin DJ, Coda B, Shen DD, et al: Effects of combining propofol and alfentanil

834

63. 64. 65. 66.

67. 68. 69. 70. 71.

72. 73. 74. 75. 76. 77. 78. 79. 80. 81. 82.

83.

RAPP

on ventilation, analgesia, sedation, and emesis in human volunteers. Anesthesiology 84:23, 1996 Payne FL, Ghia JN, Levin KJ, et al: The relationship of preoperative and intraoperative factors on the incidence of pain following ambulatory surgery. Ambulatory Surgery 3:127, 1995 Rapp SE, Ready LB, Nessly MR Acute pain management in patients with prior opioid consumption: A case controlled retrospective review. Pain 61:195, 1995 Rauck RL, Ruoff GE, McMillen JI: Comparison of tramadol and acetaminophen with codeine for long-term pain management in elderly patients. Curr Ther Res 55:1417, 1994 Reuben SS, Stein RB, Duprat KM: Intravenous regional anesthesia using lidocaine and ketorolac. Anesth Analg 81:110, 1995 Robertson GS, MacGregor DM, Jones CJ: Evaluation of doxapram for arousal from general anesthesia in outpatients. Br J Anaesth 49:133, 1977 Rogers JEG, Fleming BG, Macintosh KC, et al: Effect of timing of ketorolac administration on patient-controlled opioid use. Br J Anaesth 75:15, 1995 Rothenberg DM, Parnass SM, Litwack K, et al: Efficacy of ephedrine in the prevention of postoperative nausea and vomiting. Anesth Analg 72:58, 1991 Rusy LM, Houck CS, Sullivan LJ, et al: A double-blind evaluation of ketorolac tromethamine versus acetaminophen in pediatric tonsillectomy: Analgesia and bleeding. Anesth Analg 80:226, 1995 Schreiner MS, Nicolson SC, Martin T, et al: Should children drink before discharge from day surgery? Anesthesiology 76:528, 1992 Simone DA, Sorkin LS, Oh U, et al: Neurogenic hyperalgesia central neural correlates in responses of spinothalamic tract neurons. J Neurophysiol 66:228, 1991 Steward DJ: A simplified scoring system for the postoperative recovery room. Canad Anaesth SOCJ 22:111, 1975 Tang J, Sun R, White PF: Clinical efficacy of prophylactic antiemetics for outpatients at high-risk of postoperative emesis. Anesthesiology 83:A9, 1995 Tawfik MO, Elborolossy K, Nasr F: Tramadol hydrochloride in the relief of cancer pain: A double blind comparison against sustained release morphine [abstract]. Pain (suppl 5):S377, 1990 Thwaites BK, Nigus DB, Bouska GW: Intravenous ketorolac tromethamine does not worsen platelet function during knee arthroscopy under general anesthesia. Anesth Analg 81:119, 1995 Twersky RS, Abiona M, Thorne AC: Admissions following ambulatory surgery: Outcome in seven urban hospitals. Ambulatory Surgery 3:141, 1995 Wall PD: The prevention of postoperative pain. Pain 33289, 1988 Wetchler BV: Postoperative management, discharge and follow-up outpatient anesthesia. Anesthesiology Clinics of North America 1:113, 1987 Wetchler BV Postoperative nausea and vomiting in day-case surgery. Br J Anaesth 69(suppl 1):33S, 1992 White PF (ed): Anesthesia for ambulatory surgery. Int Anesthesiol Clin 132, 1994 Woolf C, King A: Physiology and morphology of multireceptive neurones with C-fibre afferent inputs in the deep dorsalhorn of the rat lumbar spinal cord. J Neurophysiol 58:460, 1987 Woolf C, Wall P: Morphine-sensitive and morphine-insensitive actions of C-afferent fiber input on the rat spinal cord. Neurosci Lett 64:221, 1986

Address reprint requests to Suzanne E. Rapp, MD University of Washington Department of Anesthesiology Mail Box 356540 Seattle, WA 98195-6540