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.
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Subchapter 37.1. Use of Analgesics in the Acute Abdomen
Background
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.
Comment
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
References
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: http://www.cdc.gov/nchs/fastats/ervisits.htm.
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.
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Subchapter 37.2. Acute Pain Services
Background
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
Comment
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.
References
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.
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