Skip Navigation U.S. Department of Health and Human Services
Agency for Healthcare Research Quality
Archive print banner

This information is for reference purposes only. It was current when produced and may now be outdated. Archive material is no longer maintained, and some links may not work. Persons with disabilities having difficulty accessing this information should contact us at: Let us know the nature of the problem, the Web address of what you want, and your contact information.

Please go to for current information.

Chapter 37. Pain Management

Erica Brownfield, M.D.
Emory University School of Medicine

Approximately 23 million people undergo surgery each year in the United States.1 Despite pharmacologic interventions, at least 40-50% of postoperative patients report inadequate pain relief.2 In addition, the practice of withholding analgesics due to fear of masking symptomatology and delaying diagnosis is still widespread in many emergency rooms and acute care settings. The Joint Commission on Accreditation of Healthcare Organizations (JCAHO) and the Agency for Health Care Policy and Research (AHCPR) have established guidelines for the appropriate assessment and management of pain in general and postoperatively. Yet efforts to educate clinicians as to appropriate pain management, particularly in emergency departments (ED) and following surgery, have lagged behind the available evidence.

We have taken the point of view that untreated pain represents a patient safety problem. This chapter reviews pain management techniques and interventions in 4 domains: use of analgesics in patients with acute abdominal pain, the use of acute pain services, prophylactic antiemetics during patient-controlled analgesia therapy, and non-pharmacologic interventions for postoperative pain.

Return to Contents

Subchapter 37.1. Use of Analgesics in the Acute Abdomen


The use of analgesics in patients with acute abdominal pain has traditionally been condemned. The 1987 edition of Cope's Early Diagnosis of the Acute Abdomen states "though it may appear crude, it is really prudent to withhold morphine until a reasonable diagnosis has been made and a plan of action formulated."1 The most recent edition of Cope's Early Diagnosis of the Acute Abdomen (1996) begins to question this long-accepted dogma, but still states that analgesia medication should be given only after a "responsible surgeon" takes a thorough history and performs a thorough physical examination.3 As patients with acute abdominal pain are rarely evaluated by a surgeon within the first few hours of presentation, it seems inappropriate and inhumane to withhold pain medication if this practice is not supported by evidence.

Practice Description

Prescribing analgesics to patients with acute abdominal pain is infrequently done. When prescribed, dosages and routes vary, from intramuscular to intravenous morphine in 5 to 10 mg increments, or 0.1 mg/kg of body weight. Although JCAHO and AHCPR have established guidelines for the appropriate assessment and management of pain in general and postoperatively, neither addresses pain management in patients with acute abdomens. Therefore, the traditional practice of withholding analgesia in this setting has not been seriously challenged.

Prevalence and Severity of the Target Safety Problem

According to the National Center of Health Statistics, there were 100,385,000 total visits to US emergency departments in 1998. The most frequent principal reason for visits was stomach or abdominal pain (5.9 million).4 Despite studies suggesting that the early administration of pain medication is safe and does not interfere with, and may actually facilitate, the ability to make a correct diagnosis, recent surveys of emergency room physicians and surgeons indicate that the majority withhold analgesics in patients presenting with an acute abdomen. Wolfe et al2 surveyed 443 emergency medicine physicians and found that although 85% believe that the conservative administration of pain medication did not change important physical findings, 76% choose not to give an opiate analgesic until after the examination by a surgeon. Graber et al5 surveyed 131 practicing surgeons in Iowa and found 67% agreed that pain medications interfere with diagnostic accuracy, and 82% cited their concerns about diagnostic accuracy when deciding to withhold pain medication.

Opportunities for Impact

Limited data suggest that the number of patients with acute abdominal pain who actually receive pain relief before surgical evaluation is small. Therefore, by educating providers in appropriate pain management for these patients, the potential impact in emergency departments across the country is large.

Study Designs

Five prospective randomized controlled trials (Level 1) were evaluated. Four of the 5 used a double-blind design. In each study, patients were randomly assigned to receive opiate analgesia or placebo, and evaluated pre- and post-intervention for pain using variations of visual analog scales (Table 37.1.1).

Study Outcomes

All 5 studies evaluated the effects of analgesia on pain relief (Level 1), and diagnoses and treatment decisions (Level 2) in patients with acute abdominal pain. Two studies evaluated the effects of analgesia on physical examination findings and one evaluated the effects of analgesia on the diagnostic performance of ultrasonography in patients with acute abdominal pain (Level 3).

Evidence for Effectiveness of the Practice

All 5 studies showed that provision of analgesia decreased pain more than it decreased localization of tenderness. None of the 5 studies indicate that the practice of providing early analgesia is harmful. Specifically, no study found compromises in diagnosis or treatment of the acute abdomen after increasing the use of analgesia.

Potential for Harm

The traditional belief that analgesic use in patients with acute abdominal pain may mask signs and symptoms, delay diagnosis, and lead to increased morbidity and mortality was not supported in these studies. All 5 studies analyzed diagnostic or management errors that occurred in each group.

Attard et al6 found no difference in localization of physical signs, and no difference in the surgeon's diagnostic confidence or management decision (to operate or to observe) between the 2 groups (opioids vs. placebo). The decision to operate or to observe was incorrect in 2 patients in the opioid group (4%) and in 9 patients in the placebo group (18%). The surgeon's initial diagnosis one hour after the injection was incorrect in all of these patients. These same 2 patients in the opioid group were incorrectly diagnosed as having non-specific abdominal pain when first assessed, but the diagnosis was subsequently changed and both patients had an inflamed appendix removed within 24 hours of admission. Neither appendix was perforated. There were no deaths or side effects from the injection for either group.

LoVecchio et al7 documented changes in localization of physical examination findings and differences in diagnosis between patients receiving opioid analgesia and placebo. The use of opioids was associated with some change in tenderness and localization in half the patients but led to no delays in care or eventual morbidity. The emergency department diagnosis differed from the final discharge diagnosis in 4 of the 49 total patients. One such patient had received placebo and 3 had received high-dose morphine (no significant difference). There was no delay in outcome or time to treatment in any patient.

Zoltie8 demonstrated that 17/134 (12%) of those receiving opioids had altered physical signs. Of the 50 patients (out of 288 in the total opiate and placebo groups) whose signs changed during the evaluation, the most common change (n=32) was alteration in bowel sounds. The remaining 18 had altered sites of tenderness, in most cases a migration of a large region to a smaller, more precise area. In no case was the diagnosis altered by a change in physical signs. To the contrary, the correct diagnosis was facilitated in several cases, particularly in the 18 cases where the site of pain changed.

Vermeulen et al9 also found that the use of opioids did not change the appropriateness of the surgeons' decision making. Among female patients, the decision to operate was appropriate more often in the opioid group, but the difference between this group and the placebo group was not statistically significant. In male patients and overall, opiate analgesia did not influence the appropriateness of the decision. The appropriateness to discharge patients without surgery was 100% in both groups. No patient who had left the hospital after 24 hours of observation without surgery was readmitted or operated on at another local hospital. The study also assessed the impact of analgesia on the accuracy of abdominal sonography. For diagnosis of appendicitis, ultrasound had lower sensitivity (71.1%) and higher specificity (65.2%) in the opioid group than in the placebo group, 80.6% and 53.8%, respectively.

Similarly, Pace et al10 found 3 diagnostic or management errors in each group (out of 35 morphine and 36 control patients). The use of opioids did not alter the physicians' ability to evaluate accurately and treat patients appropriately.

Costs and Implementation

The costs associated with implementing appropriate analgesic practice for patients with acute abdominal pain are limited to physician education programs and the cost of the analgesia and associated monitoring. There were no cost outcomes reported in any of the 5 studies.


From the available evidence, we conclude that appropriate use of analgesics in patients with acute abdominal pain effectively decreases pain and does not interfere with diagnosis or treatment. Recent surveys suggest many physicians believe conservative administration of pain medication does not interfere with diagnosis and treatment of patients with acute abdominal pain. Despite this recognition, the gap between understanding and practice remains large, and abdominal pain is often undertreated.

Table 37.1.1. Randomized controlled trials of analgesia in patients with acute abdominal pain*

Study Study Participants; Intervention Outcomes Resultsa
Zoltie, 19868 268 adults with acute abdominal pain admitted to a hospital in the UK; sublingual buprenorphine vs. placebo Level 1

Pain better after 1 hour: 64/134 vs. 59/122 (p=NS). Only 6/32 (19%) patients who received no tablet reported pain was better after 1 hour

Change in physical signs after 1 hour: 22/134 (16%) vs. 24/122 (20%); when site of tenderness changed, it usually was resolution of a large region to a smaller, precise area

In no case was the diagnosis altered by a change in physical signs

Attard, 19926 100 selected adults admitted with clinically significant abdominal pain; intramuscular papaveretum vs. placebo Level 1

Pain score: 3.1 vs. 8.3 (p<0.0001)

Tenderness score: 5.1 vs. 8.3 (p<0.0001)

Diagnostic or management errors: 2/50 vs. 9/50 (p=0.05)

Pace, 199610 75 patients with acute abdominal pain at a US military emergency department; morphine Level 1

Improvement in painb: 3.9±2.8 vs. 0.8±1.5 (p<0.01)

Accuracy of provisional diagnosis: no difference between groups

Diagnostic or management errors: 3/35 vs. 3/26 (p=NS)

LoVecchio, 19977 49 adults with acute abdominal pain and peritoneal signs ("acute abdomen") admitted to the emergency department of a tertiary care hospital in NY; intravenous morphine vs. placebo Level 1

Pain after 15 minutes: subjective and objective improvement with morphine (p<0.005) but not with placebo (p≥0.05)

Significant change in physical exam with regard to tenderness and localization: 16/32 vs. 1/16 (p<0.005)c

Initial and final diagnosis differed in 4 patients (morphine 3, placebo 1) but there was no delay in outcome or time to treatment (by retrospective chart review)

Vermeulen, 19999 340 adults with pain in the right lower part of the abdomen at a university hospital emergency department; intravenous morphine vs. placebo Level 1

Pain after approx. 45 minutes: significantly reduced with placebo and, to a greater extent, with morphine (p<0.001)

Ultrasound had lower sensitivity (71.1% vs. 80.6%, p<0.05) and higher specificity (65.2% vs. 53.8%, p<0.05) in patients who received morphine.

The negative predictive value of US was significantly lower in female patients who received morphine rather than placebo. Other changes in predictive value did not achieve statistical significance.

Opiate analgesia did not significantly influence the appropriateness of the decision to operate

* NS indicates not statistically significant.

a Results are reported as intervention group vs. control group.

b Pain was measured on visual analog scale; larger values represented greater pain relief.

c Change in tenderness from 2 or more quadrants to one and the loss of rebound tenderness or vice versa were considered significant


1. Silen W. Cope's early diagnosis of the acute abdomen, 17th ed. New York: Oxford University Press; 1987.

2. Wolfe JM, Lein DY, Lenkoski K, Smithline HA. Analgesic administration to patients with an acute abdomen: a survey of emergency medicine physicians. Am J Emerg Med 2000;18:250-153.

3. Silen W. Cope's Early Diagnosis of the Acute Abdomen. 19th ed. New York: Oxford University Press; 1996.

4. Centers for Disease Control and Prevention. NCHS-FASTATS-Emergency Department Visits. Available at: Accessed April 1, 2001.

5. Graber MA, Ely JW, Clarke S, Kurtz S, Weir R. Informed consent and general surgeons' attitudes toward the use of pain medication in the acute abdomen. Am J Emerg Med 1999;17:113-116.

6. Attard AR, Corlett MJ, Kidner NJ, Leslie AP, Fraser IA. Safety of early pain relief for acute abdominal pain. BMJ 1992;305:554-556.

7. LoVecchio F, Oster N, Sturmann K, Nelson LS, Flashner S, Finger R. The use of analgesics in patients with acute abdominal pain. J Emerg Med 1997;15:775-779.

8. Zoltie N, Cust MP. Analgesia in the acute abdomen. Ann R Coll Surg Engl 1986;68:209-210.

9. Vermeulen B, Morabia A, Unger PF, Goehring C, Skljarov I, Terrier F. Acute appendicitis: influence of early pain relief on the accuracy of clinical and US findings in the decision to operate—a randomized trial. Radiology 1999;210:639-643.

10. Pace S, Burke TF. Intravenous morphine for early pain relief in patients with acute abdominal pain. Acad Emerg Med 1996;3:1086-1092.

Return to Contents

Subchapter 37.2. Acute Pain Services


The concept of an acute pain service (APS) was first reported in 1988. Its genesis was the recognition of the problems wrought by inadequate postoperative pain management and appreciation that acute pain may prolong recovery or precipitate complications. Over the past 15 years, in the United States and worldwide, hospitals have created multidisciplinary acute pain services, with specially trained staff and resources geared toward providing up-to-date techniques and education. The APS creates a framework in which postoperative pain can be managed more effectively, hopefully leading to less discomfort and fewer postoperative complications.

Practice Description

An APS attempts to bridge the gap between physicians, nurses and patients to coordinate pain management. The roles of the APS are 1) educating patients, 2) educating nurses and physicians, 3) selecting appropriate analgesic techniques for different situations, 4) preparing guidelines for different analgesic regimens, 5) helping to manage acute pain problems, and 6) performing quality control activities.

Most acute pain services in the United States are anesthesiology-based. The comprehensive pain management teams usually consist of staff anesthesiologists, resident anesthesiologists, specially trained nurses, pharmacists and physiotherapists. Some services are nurse-based rather than anesthesia-based.

Prevalence and Severity of the Target Safety Problem

Approximately 50% of patients undergoing surgery do not receive adequate pain relief.1 Failure to appropriately treat pain stems from lack of knowledge and skills on the part of healthcare providers and those responsible for healthcare system management, and insufficient patient education. The "safety" problem targeted by the practice of implementing an APS is postoperative pain and morbidity.

Opportunities for Impact

Approximately 34-44% of hospitals in Europe2,3 and most major institutions in the United States4 have organized APSs. In general, few smaller hospitals have an APS. Therefore, there are many opportunities to institute acute pain services in hospitals.

Study Designs

Six articles were reviewed for this chapter. All are observational studies; one with a control, 5 without controls. All 6 studies looked at the intervention of an acute pain service in patients undergoing surgery (Table 37.2.1).

Study Outcomes

Three of the 6 studies assessed postoperative pain (Level 1). Two of the 6 studies assessed adverse effects and safety (Level 2) and one assessed knowledge and attitudes, perceived adequacy of patients' pain relief and the effect on staff workload and relationships.

Evidence for Effectiveness of the Practice

All 3 studies that assessed postoperative pain scores found improvements. Bardiau et al2 showed that differences in pain score were most pronounced (around 50%) in patients undergoing vascular, maxillofacial, gynecologic, oral and urologic surgeries. Gould et al5 showed a reduction in median visual analog scores for pain during relaxation, movement and deep inspiration. Tighe et al6 showed a significant improvement in patient perception of pain relief after introduction of an APS.

Schug and Torrie7 found no complications resulting in sustained morbidity or mortality when anesthesiology-based APS provided postoperative pain relief. Potentially severe complications (without sequelae) occurred in 0.53% of patients. In one study by Tsui et al,8 1.8% of patients developed respiratory complications (bradypnea, hypercapnia, oxygen desaturation), 1.2% developed hypotension, and 28.8% and 15.1%, respectively, developed nausea and vomiting. None suffered long-term sequelae.

Although the postoperative setting is a logical place for acute pain services, they may also be useful in patients who experience pain as part of a disease process. Although used more for managing chronic conditions such as cancer and low back pain, acute pain services are also gaining popularity in treating hospitalized patients with pain due to a medical condition. There are no rigorous trials of APSs as they are used for medical patients.

Potential for Harm

Fragmentation of care (i.e., lack of continuity between the anesthesiologist performing preoperative evaluation and anesthesiologist providing postoperative pain control, or fragmentation of care among multiple physicians) and decreased attention by the physician-of-record may result in problems from the intervention. However, no studies have examined these concerns.

Costs and Implementation

Although none of the studies directly examined costs of implementing an acute pain service, one study estimated that an APS might be cost-effective.6 Some data suggest that a nurse-based APS may be more cost-effective than an anesthesiologist-based APS, although there are no formal analyses of this supposition.9

Principal obstacles to implementing such acute pain services include financial constraints, the challenges of educating newly qualified doctors regarding pain management, and the complexity of published guidelines.9


Studies of APSs are mostly observational, measuring postoperative pain, adverse outcomes and staff knowledge and attitudes regarding its implementation. Although these studies indicate that acute pain services can improve postoperative pain without endangering patient safety, no formal recommendation can be made in the absence of high quality, systematic reviews of the benefits, costs and feasibility of implementing these services.

Table 37.2.1. Studies of acute pain services in postoperative pain management*

Study Setting Study Design, Outcomes Results
1304 patients in the pre-APS inception phase and 671 patients after its implementation undergoing various surgeries in a university teaching hospital2 Level 3, Level 1 Significant reduction of all pain indicators after APS inception (p<0.0001); major improvement (>50%) in patients undergoing vascular, maxillofacial, gynecologic, urologic and oral surgeries
2035 patients undergoing various surgical operations at a university hospital5 Level 3, Level 1 Reduction in mean pain from 45 (95% CI: 34-53) to 16 (95% CI: 10-20) after APS
1518 patients undergoing various surgeries at a district general hospital6 Level 3, Level 1 Significant reduction of pain (p<0.0001) after APS
2509 patients under APS care at a tertiary referral teaching hospital; 1759 received systemic analgesia, 590 epidural; 160 other techniques8 Level 3, Level 2 Side effects were unusual (1.8% respiratory, 1.2% hypotension, 28.8% nausea, 15.1% vomiting)
3016 patients treated by an APS for postoperative pain7 Level 3, Level 2 0.53% potentially severe adverse reactions and no severe complications
48 staff members (36 nurses, 12 house officers) working in two surgical units10 Level 3, Level 3 Two-thirds of staff thought APS decreased their workload; perception of patient pain relief significantly better in APS unit

* APS indicates acute pain service; CI, confidence interval.


1. AHCPR. Acute pain management: operative or medical procedures and trauma, part 1. Clin Pharm 1992;11:309-331.

2. Bardiau FM, Braeckman MM, Seidel L, Albert A, Boogaerts JG. Effectiveness of an acute pain service inception in a general hospital. J Clin Anesth 1999;11:583-589.

3. Hall PA, Bowden MI. Introducing an acute pain service. Br J Hosp Med 1996;55:15-17.

4. Ready LB. How many acute pain services are there in the US and who is managing patient-controlled analgesia? Anesth 1995;82:322.

5. Gould TH, Crosby DL, Harmer M, Lloyd SM, Lunn JN, Rees GAD, Roberts DE, Webster JA. Policy for controlling pain after surgery: effect of sequential changes in management. BMJ 1992;305:1187-1193.

6. Tighe SQ, Bie JA, Nelson RA, Skues MA. The acute pain service: effective or expensive care? Anaesth 1998;53:382-403.

7. Schug SA, Torrie JJ. Safety assessment of postoperative pain management by an acute pain service. Pain 1993;55:387-391.

8. Tsui SL, Irwin MG, Wong CML, Fung SKY, Hui TWC, Ng, KFJ, Chan WS, O'Reagan AM. An audit of the safety of an acute pain service. Anaesth 1997;52:1042-1047.

9. Rawal N. Ten years of acute pain services—achievements and challenges. Reg Anesth Pain Med 1999;24:68-73.

10. McLeod GA, Davies HTO, Colvin JR. Shaping attitudes to postoperative pain relief: the role of the acute pain team. J Pain Symptom Manage 1995;10:30-34.

Return to Contents
Proceed to Next Section


The information on this page is archived and provided for reference purposes only.


AHRQ Advancing Excellence in Health Care