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ORIGINAL RESEARCH |
From the Departments of Obstetrics, Gynecology and Reproductive Medicine, and Surgery, Division of Gynecologic Oncology, State University of New York at Stony Brook, Stony Brook, New York.
Address reprint requests to: Michael L. Pearl, MD, Long Island Gynecologic Oncologists, P.C., 994 Jericho Turnpike, Smithtown, NY 11787; E-mail: mlpearl{at}notes.cc.sunysb.edu.
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ABSTRACT |
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METHODS: Over a 2.5-year period, 227 gynecologic oncology patients undergoing intra-abdominal surgery were enrolled in a randomized controlled trial of early oral versus traditional parenteral analgesia. All patients initially received parenteral morphine via a patient-controlled analgesia (PCA) pump with a basal dose of 0.5 mg/h and a PCA dose of 1 mg with a 10-minute lockout. On the first postoperative day, all patients began a clear liquid diet, which was advanced as tolerated. Patients allocated to early oral analgesia were switched from parenteral to oral morphine. They received a scheduled dose of 20 mg every 4 hours with an additional dose of 10 mg every 2 hours as needed for breakthrough pain. Patients allocated to traditional parenteral analgesia continued to receive parenteral morphine via a PCA pump with basal and PCA doses. On the second postoperative day, the scheduled oral and basal parenteral doses were discontinued. The oral and parenteral PCA doses were continued until 24 hours before discharge, at which time the patient was switched to oxycodone 5 mg/ acetaminophen 325 mg.
RESULTS: There were no significant differences among the groups in any demographic or clinical indices, including age, case distribution, surgery length, blood loss, time to return of bowel function, length of hospital stay, pain, sedation, and satisfaction scores, and incidence of nausea, vomiting, or major postoperative complications.
CONCLUSIONS: Early oral analgesia in gynecologic oncology patients undergoing intra-abdominal surgery is safe and efficacious.
Many patients with gynecologic malignancies undergo extensive intra-abdominal surgery, either primarily for tumor staging and debulking, or secondarily for treatment of complications related to prior therapy. Traditionally, gynecologic oncologists used a nasogastric tube to decompress the stomach during the immediate postoperative period. Oral feeding was withheld until return of bowel function, as evidenced by passage of flatus in the absence of nausea, vomiting, or symptomatic bowel distension.1 Contemporary data, though, indicate that routine use of a nasogastric tube does not provide any substantial benefit and that early oral feeding with a clear liquid diet is safe and well-tolerated.2,3 Thus, we have eliminated postoperative nasogastric tube decompression except in highly selected circumstances and routinely provide our patients a clear liquid diet on the first postoperative day.
Because it was believed that patients were unable to tolerate early oral feeding, the administration of postoperative pain medication has been limited to parenteral routes. At the State University of New York at Stony Brook, most patients undergoing major surgery receive postoperative parenteral opioids via a patient-controlled analgesia (PCA) pump. Recently, the need to delay oral analgesic use has been questioned in the literature. Patients undergoing cholecystectomy have received oral analgesics as early as 4 hours after surgery.4 Furthermore, it has been suggested that early oral feeding actually reduces postoperative analgesic requirements.5 However, in our prior trial of early oral feeding, the patients in the early feeding group also received oral pain medication with oxycodone 5 mg/acetaminophen 325 mg.2 The incidence of nausea in this group was nearly twice the incidence in the traditional feeding group. One possible explanation for the increased incidence is oral analgesia–induced nausea.
This prospective randomized controlled trial was undertaken to evaluate the safety and efficacy of early oral analgesia after intra-abdominal surgery in gynecologic oncology patients.
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MATERIALS AND METHODS |
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All surgical procedures were performed by the authors or by residents under the authors’ direct supervision. The anesthetic and recovery room management of the study patients were standardized and recorded. No prophylactic antiemetics were allowed. A variety of demographic and clinical indices were recorded.
All patients initially received parenteral morphine via a PCA pump with a basal dose of 0.5 mg/h and a PCA dose of 1 mg with a 10-minute lockout. On the first postoperative day, all patients began a clear liquid diet, which was advanced as tolerated in the absence of nausea, vomiting, or symptomatic abdominal distension. Patients allocated to early oral analgesia were switched from parenteral to oral morphine. They received a scheduled dose of nonsustained release oral morphine liquid, 20 mg every 4 hours, with an additional dose of 10 mg every 2 hours as needed for breakthrough pain. These doses were chosen based upon the results of a pilot trial demonstrating that they were effective and well-tolerated.6 Patients were allowed to refuse oral doses at any point throughout the study. Patients allocated to traditional parenteral analgesia continued to receive parenteral morphine via a PCA pump with basal and PCA doses. On the second postoperative day, the scheduled oral and basal parenteral doses were discontinued. The oral and parenteral PCA doses were continued until 24 hours before discharge, at which time the patient was switched to oxycodone 5 mg/acetaminophen 325 mg.
All patients rated their pain on a 10-point linear analogue scale, and nurses rated the patients’ sedation according to a 10-point sedation scale. Dose adjustments were made at 4-hour intervals according to a combination of these scores (Table 1
). Patients who reported intolerable pain or intractable symptoms despite dose adjustment were considered treatment failures and received alternative pain medication, including different opioids or a nonsteroidal anti-inflammatory drug (NSAID). On the day of discharge, the patients completed a discharge questionnaire. Standard criteria for discharge were used for all study patients.
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value of .05 and a ß value of .2, a minimum of 107 patients were required in each group.
Statistical analysis was performed using NCSS 2000 (Number Cruncher Statistical Systems, Kaysville, UT) on a Dell Dimension XPS T700r (Dell Computers, Round Rock, TX). Categoric variables (ie, incidence of postoperative complications, data from the discharge questionnaire) were analyzed by the 
2 test with Yates correction or Fisher exact test as appropriate. Continuous variables (ie, time to first passage of flatus) were initially assessed for normality numerically by testing skewness, kurtosis, and omnibus normality, and visually with a probability plot. Normally distributed continuous variables were analyzed by the unpaired Student t test. Non-normally distributed continuous variables were analyzed by the Wilcoxon rank-sum test. Tests were two-tailed when appropriate, and P < .05 was considered significant.
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RESULTS |
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Tables 2 and 3 summarize the demographic and surgical distribution. The early oral analgesia and traditional parenteral analgesia groups were similar in age, disease, and surgical procedure distribution, surgery length, and estimated blood loss.
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summarizes the morphine dose information. The groups received similar amounts of parenteral morphine via the PCA on the initial postoperative day. On subsequent days, taking bioavailability differences between oral and parenteral morphine into account, there were no clinically meaningful differences between the two groups with respect to opioid use or requirements to obtain similar analgesic outcomes.
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summarizes mean pain and sedation scores. There was no difference between the two groups with respect to mean pain or sedation score at any time point. No patient was taken off study for intolerable pain or intractable side effects.
Table 5 summarizes the gastrointestinal outcome. There was no difference between the two groups with respect to nausea, vomiting, abdominal distension, or intervals measured (time to flatus and regular diet and length of hospital stay). No patient required placement of a nasogastric tube for treatment of intractable nausea or vomiting.
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summarizes the incidence of major postoperative complications. There was no difference between the two groups with respect to any major postoperative complication.
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DISCUSSION |
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As scientific evidence accumulates to refute these historical dictums, the management of the postoperative patient has undergone substantial changes. Patients are no longer subjected to routine nasogastric tube use and are commonly provided a clear liquid diet within 24 hours of their surgery. An ongoing trial at our institution is investigating the immediate institution of a regular diet after surgery. However, patients are still denied access to early administration of oral analgesia.
One area of concern regarding early administration of oral analgesia is safety. In the present trial, the incidence of postoperative nausea was comparable in both groups, as was the incidence of vomiting and abdominal distension. These findings lay to rest the concern that early administration of oral analgesia was responsible for the increased incidence of nausea we observed in our prior trial.2 Although 14–23% of the current patients developed nausea or vomiting, the episodes were transient. These episodes occurred most frequently within the first 24 hours and may have been associated with residual effects of anesthesia or surgical manipulation of peritoneum or retroperitoneal structures. No patient required a nasogastric tube or was taken off the study for intractable nausea or vomiting. Importantly, the incidence of major complications was not increased in the early oral analgesia group.
Similar results have been reported in several studies comparing administration of oral with parenteral morphine for postoperative analgesia following non–intra-abdominal surgery (primarily orthopedic).10,11 It has been clearly shown that patients undergoing intra-abdominal surgery can tolerate oral intake within 24 hours of surgery.2,12,13 Furthermore, surgeons routinely reinstitute other oral medications immediately after surgery, including cardiac or antihypertensive agents, and there does not seem to be any reason to exclude opioids. Given that many of the patients in the current trial had multiple concomitant medical problems and underwent multiple procedures during their surgery, our results generalize the previously published recommendations to a much larger group of patients.
A second area of concern with early administration of oral analgesia is efficacy. In the current trial, the mean pain and sedation scores were comparable in both groups and showed a gradual decline over the 3-day period of the study. By the second postoperative day, the mean pain scores were minimal in both groups, reflecting excellent pain relief with both routes of administration. Furthermore, the groups were equally satisfied with their pain management. The majority would recommend their method to others and would request the same method in the future.
As anticipated, there was no difference in the mean morphine dose between the groups when each received parenteral morphine administered via a PCA pump. Subsequently, the mean morphine dose, measured as total milligrams of drug (without regard to relative bio-availability) was significantly greater in the early oral analgesia group (approximately 2:1 ratio). However, the equi-analgesic ratio between oral and parenteral morphine is not 1:1, but ranges from 2:1 to 6:1 according to a variety of factors.14 Taking this into account, the groups used comparable amounts of morphine to achieve comparable pain relief, substantiating the conclusion that oral morphine solution is well-absorbed enterally in the postoperative period. The wide variation within the groups reflects the known substantial interpatient variability in analgesic requirements. Interestingly, the early oral analgesia group only used 50% of the expected amount of morphine had they received all of their scheduled doses on the first postoperative day (63.3 mg vs. 120 mg). This indicates that, on average, the group refused half of their scheduled doses suggesting that the scheduled dose of 20 mg every 4 hours was too high. In contrast, the traditional parenteral group received 26 PCA doses in addition to their basal dose, suggesting that a basal dose of 0.5 mg/h was inadequate. Once the scheduled oral and basal parenteral doses were discontinued, the total daily dose in both groups remained the same, reflecting an increase in demand doses. However, both groups used substantially less morphine than was available to them.
The final area of concern with early administration of oral analgesia is bioavailability. It has been shown that absorption of oral morphine is delayed in the postoperative period, possibly due to gastric stasis.11,15 In contrast to the current trial, these studies used controlled-release tablets that are absorbed markedly differently than liquid morphine. Liquids are released from the stomach more rapidly than solid particles and may be released despite minimal gastric activity. Even if absorption is delayed, it is only the rate and not the extent that is altered, and scheduled dosing will still provide an effective clinical concentration. Once absorbed, orally administered opioids undergo extensive first-pass metabolism. However, there are no data to suggest that the extent of first-pass metabolism is increased in the postoperative period. Neither of these factors should be an issue as long as dosing is based upon the patients’ response, rather than providing a fixed dose.
The results of our trial indicate that early initiation of oral analgesia using an opioid in solution is safe and effective in gynecologic oncology patients undergoing major intra-abdominal surgery. We chose oral morphine because it has many potential benefits compared with parenteral morphine. It is simple to administer and titrate, has a rapid onset, is readily acceptable, widely available, and inexpensive. In our institution, an average course of postoperative oral morphine costs the pharmacy 86 cents (160 mg total, 20 mg/mL, $12.89/120 mL) compared with $7.25 for parenteral administration with a PCA machine (110 mg total requiring single nonreusable 150-mg cassette, $7.25 per cassette). This estimate does not take into account ancillary costs (nursing or pharmacy time, pump maintenance, etc). It has been estimated that the ‘true’ cost of PCA administration ranges from $27.79 to $35.82 per day.16 Based on these results and those of other published studies,16 we have discontinued using a PCA machine in favor of regularly scheduled intramuscular injections for the first postoperative night and switching to oral medication for the remainder of the hospitalization. This approach should achieve equal efficacy with substantial cost savings.16 Ultimately, patients may be able to dispense their own oral medication via an oral PCA system.17 A scheduled oral morphine dose of 10 mg every 4 hours and an as-needed dose of 5 mg every 2 hours should provide effective pain control with minimal side effects. As is standard with other routes of administration, the dosing should be individualized according to the patient’s needs and side effects.
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Footnotes |
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Received October 2, 2001. Received in revised form January 4, 2002. Accepted January 31, 2002.
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REFERENCES |
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2. Pearl ML, Valea FA, Fischer M, Chalas E. A randomized controlled trial of postoperative nasogastric tube decompression in gynecologic oncology patients undergoing intra-abdominal surgery. Obstet Gynecol 1996;88:399–402.[Abstract]
3. Pearl ML, Valea FA, Fischer M, Mahler L, Chalas E. A randomized controlled trial of early post-operative feeding in gynecologic oncology patients undergoing intra-abdominal surgery. Obstet Gynecol 1998;92:94–7.[Abstract]
4. Treen DC, Downes TW, Hayes DH, McKinnon WM. Outpatient cholecystectomy simulated in an inpatient population. Am Surg 1991;57:39–45.[Medline]
5. Moss G, Regal ME, Lichtig L. Reducing postoperative pain, opioids and length of hospitalization. Surgery 1986; 99:206–10.[Medline]
6. McCormack JP, Warriner CB, Levine M, Forster-Coull J. Regularly scheduled oral morphine for post surgical orthopedic pain. Canadian Journal of Hospital Pharmacy 1992; 45:101–5.
7. Meehan DA, McRae ME, Rourke DA, Eisenring C, Imperial FA. Analgesic administration, pain intensity and patient satisfaction in cardiac surgical patients. AM J Crit Care 1995;4:435–42.
8. Ferrante FM, Orav EJ, Rocco AG, Gallo J. A statistical model for pain in patient-controlled analgesia and conventional intramuscular and opioid regimens. Anesth Analg 1988;67:457–61.
9. McGrath D, Thurston N, Wright D, Prenshaw R, Fermin P. Comparison of one technique of patient-controlled postoperative analgesia with intramuscular meperidine. Pain 1989;37:265–70.[Medline]
10. Bourke M, Hayes A, Doyle M, McCarrol M. A comparison of regularly administered sustained release oral morphine with intramuscular morphine for control of postoperative pain. Anesth Analg 2000;90:427–30.
11. Derbyshire DR, Bell A, Parry PA, Smith G. Morphine sulfate slow release. Comparison with IM morphine for postoperative analgesia. Br J Anaesth 1985;57:858–65.
12. Hessov L, Larsen KR, Sondergaard K. Improved early alimentation after radical hysterectomies without the traditional use of stomach tube. Acta Obstet Gynecol Scand 1988;67:225–8.[Medline]
13. Soriano D, Dulitzki M, Keidar N, Barkai G, Mashiach S, Seidman DS. Early oral feeding after cesarean delivery. Obstet Gynecol 1996;87:1006–8.[Abstract]
14. Inturrisi, C. Management of cancer pain. Pharmacology and principles of management. Cancer 1989;63:2308–20.[Medline]
15. Lew JK, Mobley KA, Achola KJ, Horne A, Smith G. Postoperative absorption of controlled-release morphine sulfate. A study in patients given parenteral opioids. Anesthesia 1989;44:101–3.
16. Rittenhouse BE, Choiniere M. An economic evaluation of pain therapy after hysterectomy. Int J Technol Assess Health Care. 1999;15:548–62.[Medline]
17. Pasero C. Oral patient-controlled analgesia. Am J Nurs 2000;100:24.
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M. L. Pearl, M. Frandina, L. Mahler, F. A. Valea, P. A. DiSilvestro, and E. Chalas A Randomized Controlled Trial of a Regular Diet as the First Meal in Gynecologic Oncology Patients Undergoing Intraabdominal Surgery Obstet. Gynecol., August 1, 2002; 100(2): 230 - 234. [Abstract] [Full Text] [PDF]
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