Preventing pain after cardiac surgery

From theory to practice: preventing pain after cardiac surgery

Jocelyn Reimer-Kent

A pain management guideline was developed at the Royal Columbian Hospital, New Westminster, British Columbia, to prevent pain after cardiac surgery. The guideline was based on a wellness model and was predicated on the World Health Organization’s analgesic ladder. Patients are given nonopioids around the clock and throughout the postoperative stay and are given an opioid to prevent procedural pain and treat breakthrough pain. In an evaluation of the guideline, records from 133 cardiac surgery patients were retrospectively reviewed. The type and dose of analgesics administered for the first 6 days after surgery, the effectiveness of the pain management plan, the occurrence of adverse effects, time to extubation, and postoperative lengths of stay were determined. Ninety-five percent of patients had effective pain relief Almost all patients received acetaminophen around the clock. A total of 89% received indomethacin. All patients received opioids intermittently. Doses of opioids were converted to morphine oral equivalents, which peaked on day 1 after surgery (38 equivalents) and decreased sharply by day 2 (<10 equivalents). Median postoperative length of stay was 5 days for patients who had bypass surgery and 6 days for patients who had valve surgery. This proactive, low-tech, low-risk, well-tolerated pain management approach is cost-effective, simple, and feasible to use. The findings support use of this approach in managing pain after cardiac surgery. (American Journal of Critical Care. 2003;12:136-143)

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Pain management is an important issue in patient care that transcends institutional, regional, national, and international boundaries. Universally, the goal is to provide effective pain relief. The World Health Organization (WHO) has addressed this goal by developing a framework for managing pain. (1) Accreditation standards have evolved and now include specific expectations about the management of pain. (2,3)

Pain is also a topic of interest in practice and research. (4,5) A review of the research literature revealed that pain is often inadequately managed. (6-8) Sadly, this knowledge has had little impact on practice. (9,10) For example, although postoperative pain is moderate to severe and persists long after the surgery, practice is often based on the mistaken belief that pain is mild and diminishes quickly. (10-12) An added concern is that a lack of attention to relieving acute pain may contribute to the onset of chronic pain. (4,10,13)

Acute Postoperative Pain

Acute pain after surgery is inevitable because of the associated trauma to many pain-sensitive structures. (4,10,14) An inflammatory response to this trauma triggers the release of numerous chemical mediators in the periphery. These mediators lower the nociceptor threshold, making the receptors more responsive to painful stimuli. The dorsal horn receives these peripheral impulses and transmits them via central pathways to the brain. (4,13,15)

Pain is more than just a physical process; it is a complex, subjective phenomenon. (4,16,17) Pain can impair the hematologic, immune, hormonal, cardiac, and respiratory systems. (9,18) Pain also can limit mobility, (10,14,18) interfere with sleep and rest, and contribute to agitation, psychosis, aggressive behavior, and delirium. (4,18,19)

Unfortunately, patients are often undermedicated and so do not have effective pain relief. (4,10,20) Numerous factors appear to influence undertreatment. (4) Healthcare providers may underestimate the amount of pain a patient is experiencing and overestimate the effectiveness of analgesics they are administering. (4,16,21) They may also tightly control analgesics to avoid contributing to drug dependency (4,20,22) and/or having to deal with drug-induced adverse effects. (8,20)

Patients fear unrelieved pain. (23) Despite this fear, they may inadvertently contribute to being undermedicated, because they may be reluctant to complain and/or to voluntarily ask for analgesics. (6) Patients also worry about drug dependency and drug-induced adverse effects. (2,4,6)

Surgical centers need to pay attention to pain management, because there appears to be a direct relationship between unrelieved pain and cost of medical care, (18) time spent in an intensive care unit, (24) and hospital length of stay. (4,18,20)

Traditional Approaches to Postoperative Pain Management

Traditionally, postoperative pain has been managed either reactively with drugs given as needed (21) or proactively with continuous infusion of analgesics. (14,25) Evidence suggests that reactive pain management is ineffective. With a reactive approach, analgesics are administered at the discretion of nurses and only on an as-needed basis. Consequently, treatment takes place after pain occurs, (20,21) causing some patients to experience severe pain. (14,21,24) In contrast, proactive pain management improves effectiveness, because treatment is given before pain occurs. (9,21) With a proactive approach, analgesics are often administered via a continuous peripheral or epidural infusion. However, because this approach may entail added risk, (4,14) is short-term, (4) hightech, (4,26) equipment dependent, (25,26) and often self-administered, (4,25) it is neither available nor appropriate for all surgical patients. (19)

Innovative Approach to Postoperative Pain Management

A challenge in healthcare is ensuring cost-effective, high-quality patient care. Decreasing length of stay is a common strategy to contain or reduce costs and an essential feature of rapid recovery programs. Quality care and patients’ safety can be maintained when care delivery systems are redesigned, as shown at the Royal Columbian Hospital in New Westminster, British Columbia. More than 600 cardiac surgeries are performed annually in this 400-bed acute care facility. In 1996, a multidisciplinary, cardiac surgery, quality improvement team created an innovative and cost-effective rapid recovery program.

To address the needs of patients and patients’ families, the team based the rapid recovery program on an evolving wellness-focused model of care. Preventing common postoperative problems, such as pain, nausea, constipation, respiratory compromise, and immobility, was pivotal to achieving the program’s expected outcomes. Care and treatment processes were streamlined to guide the clinical practice for treating each of these 5 interconnected problems. The assumption of this synergistic wellness model is that patients who are free of pain, nausea, and constipation will be more likely than patients who experience these problems to tolerate earlier feeding, (4,18) aggressive respiratory care, (14,18,19) and participation in an accelerated activity plan. (4,14,18) Further, length of stay (4,20) and overall cost of care (20) may be decreased, and access to care may be improved when a state of well-being is achieved quickly after surgery and is maintained throughout the postoperative stay. These assumptions were supported in an initial evaluation of the program.

The results of the 1996 evaluation did, however, suggest areas for improvement. The docunentation system needed revision, because no consistent method was available for retrieving data on the effectiveness of the pain management plan. Additionally, clinical attention was needed to further improve the approach to preventing postoperative pain. In the original clinical practice guideline, a less invasive, proactive pain management plan replaced continuous infusion of analgesics (peripheral or epidural catheter) controlled by either a nurse or the patient. The new plan had consisted of around-the-clock, intermittent doses of intravenous morphine (before extubation) along with around-the-clock, regular doses of 100 mg of indomethacin given rectally every 12 hours for 5 doses. After extubation, acetaminophen with codeine was administered as needed. This reactive approach was the only analgesic protocol used after the last dose of indomethacin and for patients for whom indomethacin was not appropriate.

The team noted that patients who received regular doses of indomethacin appeared to have more effective pain relief during the course of treatment than did patients who did not receive this medication. In an attempt to better manage pain immediately after surgery, some staff requested orders for around-the-clock, regular doses of acetaminophen suppositories. The staff noted that patients who were given acetaminophen also had less pain than did patients not given this drug.

The use of acetaminophen with codeine was also questioned. Although in 1996 most patients (81%) had their first postoperative bowel movement within 3 days of surgery, the team wondered whether this drug combination was contributing to a high frequency (60%) of postoperative nausea reported by the patients. In addition, staff were concerned that pain might be undertreated once acetaminophen with codeine was the only analgesic used for pain management.

The pain prevention guideline was changed in 2000 on the basis of recommendations in the literature and the WHO analgesic ladder. A regular dose of analgesics would be administered around the clock (9,19,24) and as needed to prevent procedural pain (10,27,28) and to treat breakthrough pain. (19,29) This strategy would be used throughout patients’ postoperative stay (10,24) and would include care designed to prevent and/or treat adverse effects associated with the use of analgesics. (14,20,24) This plan was to be research based, simple, feasible, and cost-effective. (20,26)

Multimodal or balanced analgesia, like that outlined in the WHO analgesic ladder, is strongly recommended for management of postoperative pain. (11,18,20) The WHO 3-step plan advocates giving patients nonopioids and opioids to reach a pain-free state. (1) In the first rung of treatment, acetaminophen and/or nonsteroidal anti-inflammatory drags (NSAIDs) are given to treat mild to moderate pain. If nonopioids do not alleviate pain, treatment proceeds to the second rung, and an opioid is added to the medication regimen. If pain persists or increases, treatment proceeds to the third rung, and nonopioids are continued and a stronger opioid is added. The WHO cancer protocol recommends that patients in moderate to severe pain start immediately on the second or third rung. Separating treatment with the nonopioid from treatment with the opioid allows around-the-clock, regular doses of nonopioids to be administered along with individually titrated around-the-clock, intermittent doses of an opioid to prevent procedural pain and to treat breakthrough pain.

Our multimodal, balanced analgesic guideline (Figure 1) includes concurrent use of acetaminophen and an NSAID (ie, indomethacin) as the nonopioids and morphine as the opioid. Although nonopioids are not expected to relieve moderate to severe postoperative pain, they harmonize well with opioids. With our approach, balance occurs because both acetaminophen and NSAIDs have a marked opioid-sparing effect on severe pain. As a result, fewer opioid-related adverse effects occur. (30-32)

[FIGURE 1 OMITTED]

Acetaminophen is a relatively safe, well-tolerated drug at therapeutic doses. (4,30,31) The exact site of action is unknown, but the drug is thought to have a primary effect on the central nervous system and a weak effect on the peripheral system. (4,30,31) A dose of 650 mg of acetaminophen is given rectally immediately after surgery, and additional doses of 650 mg are given every 6 hours thereafter. This around-the-clock regimen of regular doses is continued throughout the postoperative stay. Once the patient resumes oral intake, the dose is changed to 1000 mg orally 4 times a day. Patients are advised to continue this preventive l000-mg regimen after discharge from the hospital.

Indomethacin, a weak analgesic, is a potent NSAID because of its ability to inhibit the enzyme cyclooxygenase and the production of prostaglandins; this inhibition mitigates the effects of chemical mediators associated with inflammation. (4,20,30) Short-term use of NSAIDs is usually well tolerated. (4) However, NSAIDs can cause gastrointestinal distress (33) and renal, hepatic, and hematologic dysfunction. (4,29,30) Patients with a serum creatinine level greater than 110 [micro]mol/L (normal range 30-130 [micro]mol/L) and those with active peptic ulcer disease are excluded from receiving NSAIDs. Serum creatinine levels are monitored throughout NSAID therapy. If the level exceeds 110 [micro]mol/L, treatment is discontinued.

NSAIDs inhibit platelet aggregation and prolong bleeding time. (4) Administration of NSAIDs is started as soon as patients achieve stable hemostasis (ie, chest tube losses of blood [less than or equal to] 150 mL in the first 2 hours after surgery). Patients who qualify receive indomethacin (100 mg rectally every 12 hours) for a total of 5 doses.

Morphine has a primary effect in the brain and a secondary effect on the peripheral nervous system, where it selectively blocks nociceptor pathways. (4,22,34) Small, intermittent doses of morphine are usually well tolerated. (4) Major adverse effects include sedation, respiratory depression, and gastrointestinal distress. (4,20,34) Around-the-clock, individually titrated, (4,22) intermittent doses of morphine are started immediately after surgery. Morphine is administered to effect throughout the postoperative stay to treat breakthrough pain and/or to prevent procedural pain. The intravenous dose is 2 to 4 mg as needed; the oral dose, 5 to 10 mg as needed.

Implementation

Before this guideline was implemented, a set of preprinted doctor’s orders (Table 1), preprinted medication records, and a preprinted clinical pathway were reviewed with staff. The clinical pathway is also a documentation tool; it is used to record information on outcomes, including whether or not the patient experienced effective pain relief. The information on pain relief is obtained during nursing assessments, and although it is obtained during assessment of vital signs and as needed, it is charted only once a shift as a summary note in the clinical pathway. Patients rate their pain by using a 0 to 10 verbal numerical pain-rating scale, with 0 indicating no pain, and 10 indicating the worst imaginable pain. (4,34) Pain is rated at rest and during movement, deep breathing, and coughing. Because mild pain corresponds to a pain rating of 1 to 4, (28) a pain rating greater than 3 was to be treated as breakthrough pain. Our definition of effective pain relief was a pain rating throughout a 12-hour shift that never exceeded 3. (11)

Evaluation

Evaluation of the pain management plan was conducted between January and the end of March 2000 and was part of an overall reevaluation of the rapid recovery program. During this period, 133 (87%) of the 153 patients who had cardiac surgery were considered appropriate candidates for rapid recovery. A review of the charts revealed that 119 of the 133 patients had coronary artery bypass grafting and 14 had valve replacement or repair. The mean age was 65 years (range 38-83 years) for patients who had bypass surgery and 67 years (range 47-79 years) for those who had valve surgery. Eighty percent of the patients were men.

In order to evaluate the pain management plan, data were collected from various records. Data on effective pain relief were obtained from the clinical pathway. Information on use of nonopioids and opioids was obtained from preprinted medication records. Data on postoperative psychosis, confusion, and/or delirium were obtained from coded data on health records. The number of patients who experienced nausea, time to first postoperative bowel movement, time to extubation, and length of stay after surgery were obtained from the clinical pathway. Because this documentation system was new, some data were missing.

Information related to effective pain relief is charted as a nominal summary note (ie, “effective ” or “ineffective”) in the clinical pathway at the end of each 12-hour shift. Complete documentation was available on 120 of the 133 charts reviewed. Of these 120 patients, 114 (95%) had effective pain relief on every shift for either the first 6 days after surgery or for the entire postoperative stay if the patient was discharged in 6 days or less.

Immediately after surgery, 128 (96%) of the 133 patients received around-the-clock, regular doses of acetaminophen rectally. Once oral intake was resumed, 1000 mg of acetaminophen was given orally 4 times a day to all but 1 of the 133 patients.

Data on indomethacin use was available on 132 patients. Of these 132 patients, 117 (89%) qualified for indomethacin and were started on around-the-clock, regular doses. Figure 2 shows the number of indomethacin suppositories administered. Among the 132 patients, 61 (46%) received 5 doses.

All 133 patients received around-the-clock, intermittent doses of morphine intravenously and/or orally. Meperidine is not ordered as an analgesic because of the potential for toxic metabolites. (19,22,27) However, 72 (54%) of the 133 patients received some meperidine to control postoperative shivering. Because meperidine is also an opioid, these doses, along with the parenteral doses of morphine, were converted to morphine oral equivalents (MOE). MOE was calculated by using the following equations: 1 mg of morphine given intravenously = 3 mg of morphine given orally, and 1 mg of meperidine given intravenously = 0.3 mg of morphine given orally. (35) Table 2 gives the type of opioid administered, mean dose administered per day, MOE for each opioid per day, and total MOE administered per day for the first 6 postoperative days. On the day of surgery, patients received close to 36 MOE. This amount increased slightly on day 1 after surgery (38 MOE), then precipitously decreased by day 2 (<10 MOE).

Evaluating known adverse effects of pain and/or analgesics revealed that only 1 of 133 patients experienced postoperative psychosis, confusion, and/or delirium. Postoperative nausea was experienced by 12% of 121 patients. Data on time to postoperative bowel movement were recorded for 100 patients. Of these, 2 had their first postoperative bowel movement the day of surgery. By the third postoperative day, 96 had had a bowel movement, and by the fourth postoperative day, all 100 had had a bowel movement.

Data on time to extubation were available for 131 patients. Among these 131 patients, the mean time to extubation was 8 hours and 38 minutes. Mean postoperative length of stay for the 119 patients who had bypass surgery was 5.7 days (range 4-22 days), with a median and mode of 5 days. Mean postoperative length of stay for the 14 patients who had valve surgery was 7 days (range 5-14 days), with a median and mode of 6 days.

Discussion

This clinical practice guideline offers a comprehensive plan for preventing pain after cardiac surgery. No prior study was found that examined the use of nonopioids and opioids as discussed here. However, our findings support using this approach for treatment of acute postoperative pain.

Because 95% of patients experienced effective pain relief, members of the team were interested in data on the types and doses of analgesics administered. Acetaminophen with codeine was eliminated from the original guideline. In its place, around-the-clock, regular doses of acetaminophen were given to most patients. The team members credit the effectiveness of the pain management plan, in part, to this over-the-counter analgesic. (4,30,31)

For all patients, codeine was replaced with individually titrated, around-the-clock, intermittent doses of morphine. The mean morphine dose was 10 mg intravenously on the day of surgery, 12 mg intravenously and 2 mg orally on day 1 after surgery, and 1.8 mg intravenously and 4 mg orally on day 2. Because morphine was administered to effect, there was no predetermined maximum dose, making it difficult to comment on what the team considered a small mean dose. If this mean dose was indeed small, then our results may support the hypothesis that nonopioids have an opioid-sparing effect on acute pain. (30,32)

The main reason for including indomethacin in the analgesic plan was to treat the profound peripheral inflammatory response that results from surgical trauma. The dose, route, and duration of indomethacin administration did not change in 2000. Of interest to the team was the finding that only 46% of all patients received all 5 doses of indomethacin. When data were reviewed with them, staff members conjectured that some patients might have refused indomethacin because of the rectal route of administration. The team used this information to enhance teaching of staff and patients, because patients need to understand their role in the treatment plan and the clinical importance of being pain-free. (4)

The statistics related to adverse effects were encouraging. The frequency of postoperative nausea decreased considerably, from 60% in 1996 to 12% in 2000. Although we have not established a definitive cause for this dramatic improvement, we speculate that minimizing pain and eliminating codeine were contributing factors.

The percentage of patients who had their first postoperative bowel movement within 3 days of surgery was 96% in 2000 compared with 81% in 1996. Eliminating codeine may have played a role in this increase. In addition, almost all patients received analgesic suppositories, which may have caused rectal stimulation.

The prevalence of postoperative psychosis, confusion, and/or delirium was less than 1%, much lower than the 3% to 18% reported in the literature. (36,37) This low frequency may be associated with this preventive approach to postoperative pain.

In our cardiac surgery program, we continually look for ways to improve care. Currently, we are making several changes to the pain management plan. They include beginning administration of both acetaminophen and indomethacin during the perioperative period, (11) changing the route of administration of the NSAID from rectal to oral when the patient resumes oral intake, and continuing NSAID therapy in an around-the-clock, regular dosing regimen for the first 5 days after surgery. (11)

The results from this review may be limited because of the method used and the lack of comparison data. Clinical practice associated with our pain management guideline evolved and did not lend itself to a randomized clinical trial. However, practitioners who are using continuous infusions and/or reactive pain management approaches may be able to design a study in which usual care is compared with this comprehensive, preventive approach to postoperative pain.

Summary

Our clinical practice guideline for preventing pain after cardiac surgery is based on a wellness model that unites theory with practice and is predicated on the WHO 3-step analgesic ladder. Use of the following medications provided effective pain relief with minimal adverse effects: acetaminophen throughout the postoperative stay (around-the-clock, regular doses); indomethacin, if the patient qualified, during the first 48 hours after surgery (around-the-clock, regular doses); and morphine throughout the postoperative stay to prevent procedural pain and treat breakthrough pain (around-the-clock, intermittent doses).

This preventive, low-tech, low-risk, well-tolerated pain management approach is cost-effective, simple, and feasible. The results of our evaluation support using this approach to manage patients who have acute pain after cardiac surgery.

Table 1 Preprinted doctor’s orders

Pain Management–Aim for patient comfort ie, [greater than or equal to] 3 (0-10) numeric pain rating scale

* If serum creatinine is [greater than or equal to] 110 and NO history of active peptic ulcer disease–TOTAL 5 doses post-op–Indomethacin Suppository 100 mg PR q 12h

* Until oral intake established–Acetaminophen suppository 650 mg PR q6h

* Until oral intake established–Morphine 2-4 mg IV PRN to treat pre-procedural and breakthrough pain

* When oral intake established–Acetaminophen 1000 mg po qid reassess 7 days post-op

* When oral intake established–Morphine solution 5-10 mg po PRN to treat pre-procedural and breakthrough pain

IV indicates intravenously; mg, milligrams; po, orally; post-op, postoperatively; PR, rectally; PRN, as needed; qid, four times a day; q6h, every 6 hours; q12h, every 12 hours.

Reprinted with permission from Royal Columbian Hospital, New Westminster, British Columbia.

Table 2 Summary of opioids: type, daily mean dose, daily mean dose in

morphine oral equivalents (MOE), and daily total MOE

Day after surgery

0 1 2 3

Mean, Mean, Mean, Mean,

Opioids mg MOE mg MOE mg MOE mg MOE

Intravenous 19.0 5.7 0.0 0.0 0.0 0.0 0.0 0.0

meperidine

Intravenous 10.0 30.0 12.0 36.0 1.8 5.4 0.2 0.6

morphine

Oral 0.0 0.0 2.0 2.0 4.0 4.0 3.3 3.3

morphine

Total MOE 35.7 38.0 9.4 3.9

Day after surgery

4 5 6

Mean, Mean, Mean,

Opioids mg MOE mg MOE mg MOE

Intravenous 0.0 0.0 0.0 0.0 0.0 0.0

meperidine

Intravenous 0.0 0.0 <0.1 0.2 0.0 0.0

morphine

Oral 2.4 2.4 1.4 1.4 1.8 1.8

morphine

Total MOE 2.4 1.6 1.8

ACKNOWLEDGMENTS

I gratefully acknowledge the contribution of the multidisciplinary cardiac surgery team at the Royal Columbian Hospital for their help in developing and implementing this initiative. Help with data collection from Dotsie Clarke-Mastin, RN, BScN, Lori Hughes, RN, BScN, and Andree Bamforth, RN, BScN, and with data analysis from Connie Magnusson, RN, BSN, MEd, is also acknowledged and greatly appreciated.

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Jocelyn Reimer-Kent, RN, MN. From the Cardiac Surgery Program, Royal Columbian Hospital, Fraser Health Authority, New Westminster, British Columbia, and the School of Nursing, University of British Columbia, Vancouver, British Columbia.

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