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AMBULATORY ANESTHESIA

A Comparison of Three Antiemetic Combinations for the Prevention of Postoperative Nausea and Vomiting

M. J. Sanchez-Ledesma, MD PhD^*, L. López-Olaondo, MD PhD^*, F. J. Pueyo, MD PhD^*, F. Carrascosa, MD PhD^*, and A. Ortega, MD PhD

Departments of *Anesthesiology and Critical Care and Pharmacology, University Clinic, School of Medicine, University of Navarra, Pamplona, Spain

Address correspondence and reprint requests to Javier Pueyo, Avda. Pio XII, 36, 31007 Pamplona, Spain. Address e-mail to jpuevi{at}unav.es

	Abstract

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In this study we compared the efficacy and safety of three antiemetic combinations in the prevention of postoperative nausea and vomiting (PONV). Ninety ASA status I–II women, aged 18–65 yr, undergoing general anesthesia for major gynecological surgery, were included in a prospective, randomized, double-blinded study. A standardized anesthetic technique and postoperative analgesia (intrathecal morphine plus IV patient-controlled analgesia (PCA) with morphine) were used in all patients. Patients were randomly assigned to receive ondansetron 4 mg plus droperidol 1.25 mg after the induction of anesthesia and droperidol 1.25 mg 12 h later (Group 1, n = 30), dexamethasone 8 mg plus droperidol 1.25 mg after the induction of anesthesia and droperidol 1.25 mg 12 h later (Group 2, n = 30), or ondansetron 4 mg plus dexamethasone 8 mg after the induction of anesthesia and placebo 12 h later (Group 3, n = 30). A complete response, defined as no PONV in 48 h, occurred in 80% of patients in Group 1, 70% in Group 3, and 40% in Group 2 (P = 0.004 versus Groups 1 and 3). The incidences of side effects and other variables that could modify the incidence of PONV were similar among groups. In conclusion, ondansetron, in combination with droperidol or dexamethasone, is more effective than dexamethasone in combination with droperidol in women undergoing general anesthesia for major gynecological surgery with intrathecal morphine plus IV PCA with morphine for postoperative analgesia.

IMPLICATIONS: The combination of ondansetron plus dexamethasone or droperidol was significantly better than the combination of dexamethasone plus droperidol in the prophylaxis of postoperative nausea and vomiting in women undergoing general anesthesia for major gynecological surgery, with intrathecal and IV morphine (patient-controlled analgesia) for management of postoperative pain.

	Introduction

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Postoperative nausea and vomiting (PONV) are the most common complaints after anesthesia and surgery. Patients often perceive PONV as one of the most bothersome anesthesia-related adverse effects and may consider it as distressing as the pain associated with the surgical procedure (1). PONV can contribute to the development of medical complications (2–4), and patients with PONV consume more resources and require additional health care professional time compared with patients in whom these complications are avoided.

The overall incidence of PONV during the first 24 h after surgery is approximately 30%, with considerable variability (5). This percentage may be larger depending on preoperative patient characteristics, factors related to the operation and anesthesia, and the intensity of pain and its management in the postoperative period (6). For example, the incidence of PONV in women undergoing abdominal or gynecological surgery with general anesthesia and IV patient-controlled analgesia (PCA) with morphine for postoperative pain can be as frequent as 72% (7) and 80% (8).

Intrathecal and systemic opioids provide highly satisfactory postoperative analgesia but are associated with a frequent incidence of PONV (9,10). Single-drug prophylaxis, despite being better than placebo, has a very frequent failure rate in situations with severe, frequent PONV. It is rational to give a combination of antiemetics with different mechanisms of action, and there is evidence that combinations can act synergistically (11,12).

We compared the efficacy and safety of the combinations of ondansetron plus droperidol, dexamethasone plus droperidol, or ondansetron plus dexamethasone in the prevention of PONV in patients undergoing general anesthesia for major gynecological surgery, with intrathecal morphine and IV morphine PCA for postoperative pain.

	Methods

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A prospective, double-blinded, randomized study was conducted. The study had local Ethics Committee approval, and signed, informed consent was obtained from each patient. Ninety women, ASA status I–II, aged 18–65 yr, weighing 45–90 kg, undergoing major elective gynecological surgery, were studied. Those who had taken opioids, nonsteroidal antiinflammatory drugs, steroids, or antiemetics during the previous month; were hypersensitive to droperidol, ondansetron, or steroids; or had any exclusion criteria for receiving intrathecal opioid analgesia were excluded. Patients were allocated randomly to one of the three groups of antiemetic prophylaxis. An independent person did the randomization. It was a single aleatory assignment.

The night before surgery, we recorded age, weight, and height; previous general anesthesia and abdominal surgery; history of PONV, motion sickness, or headache; cigarette consumption; phase of menstrual cycle; and grade of anxiety. All patients were taught how to use the PCA pump and were told to call the nurse as soon as they felt nausea or had any emetic episode (EE) in the postoperative period. Once in the operating room, 0.2 mg of preservative-free morphine was administered intrathecally to every patient.

Each patient received two syringes just after the induction of anesthesia and one 12 h later, all of them with 2 mL of solution. Our pharmacy department prepared these syringes. Patients in Group 1 received ondansetron 4 mg and droperidol 1.25 mg after the induction and 1.25 mg of droperidol 12 h later. Women in Group 2 received dexamethasone 8 mg and droperidol 1.25 mg after the induction and 1.25 mg of droperidol 12 h later. Those in Group 3 received ondansetron 4 mg and dexamethasone 8 mg and received 2 mL of saline 0.9% 12 h later.

The intraoperative anesthetic and postoperative analgesic management was standardized in all patients. General anesthesia was induced with atropine (0.01 mg/kg), thiopental (5 mg/kg), atracurium (0.5 mg/kg), and fentanyl (2 µg/kg). A nasogastric tube and a urinary bladder catheter were inserted in all patients. Anesthesia was maintained with nitrous oxide in oxygen (40%) supplemented with desflurane (2%–3% expired concentration). It was not necessary to antagonize residual neuromuscular block in any patient. No other sedative, analgesic, or antiemetic drug was administered. Postoperative analgesia was provided by morphine with IV PCA (Provide Pain Management^®; Abbott Laboratories, North Chicago, IL).

Postoperative variables were collected in the recovery room (2 h after the end of anesthesia) and in the hospitalization area (12, 24, and 48 h after recovery from anesthesia). Antiemetic efficacy was assessed by monitoring the incidence of PONV and the need for rescue antiemetic. Patients were asked if they felt nauseated in each period, with two possible answers: "yes," if they did for at least 10 min, or "no." Retching and vomiting were grouped together under the common category EE and were assessed as present or absent. The primary end point of the study was the complete response and was defined as no nausea or EE during the 48-h postoperative period. Patients were specifically advised to call the nurse as soon as they felt any symptom, not only PONV but also any side effect. If patients experienced nausea for 30 min or had more than one EE in 15 min, they received metoclopramide 10 mg every 8 h.

Pain intensity scores, with and without active movement, were measured with the visual analog scale (VAS). The scale was explained to patients in the preoperative period. If patients asked for analgesics or experienced pain with a VAS more than 3, they received 2 g of IV propacetamol. Total morphine consumption was also recorded.

The severity of sedation was classified into 5 categories: 4 = fully awake, open eyes; 3 = drowsy, closed eyes; 2 = asleep, responds to verbal commands; 1 = asleep, responds to touch or pain; 0 = does not respond. Other side effects and their management were also considered.

Trained nurses recorded information, and nausea and EE were also assessed by the same anesthesiologist interviewing the patient. Both were blinded to the antiemetic combination the patient received.

It was estimated that with 30 patients per prophylaxis group, a difference of 35% in clinical efficacy among groups could be found with a statistical power of 80% and a cutoff point for significance of 0.05. Gaussian distribution of variables was checked by the Shapiro-Wilks test. Differences in continuous variables among the three alternatives were evaluated by a parametric analysis of variance test or a Kruskal-Wallis test according to variable distribution. A Tukey test and Mann-Whitney U-test with Bonferroni’s correction were used for post hoc comparisons. Frequencies were compared by a contingence test based on ² and Fisher’s exact tests. The influence of antiemetic combinations in the incidence of PONV, adjusted for other clinical variables, was determined by multiple logistic regression analysis. To include a variable in this analysis we used the maximum likelihood test, which is more sensible than the Wald ² test. Parametric data are presented as mean (SD) and nonparametric data as median (interquartile range). In every statistical test, the cutoff point for significance was 0.05. The statistical analysis was performed with SPSS for Windows Version 8.0 (SPSS Inc., Chicago, IL) (13).

	Results

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There were no significant differences among the groups in factors that could modify the incidence of PONV as background factors, factors related to the operation, or anesthesia (Table 1).

View larger version (37K): [in this window] [in a new window]   Figure 1. Number of patients without postoperative nausea and vomiting in each group from the end of surgery until the moment of each evaluation. Group 1 = ondansetron plus droperidol; Group 2 = dexamethasone plus droperidol; Group 3 = ondansetron plus dexamethasone. *P < 0.05, Group 1 versus Group 2 and Group 3; **P < 0.01, Group 1 versus Group 2 and Group 3.

There was no significant difference in pain intensity among groups at any period. At 48 h, no patient at rest and 21 with movement had a VAS score more than 3. Among all patients, 17 required analgesic rescue. Only 1 patient from Group 1 asked for more analgesia in the first 12 h, as did 11, equally distributed in the 3 groups, in the 12- to 24-h period. No patient required more than one dose of propacetamol in each period. Opioid requirements were no different among groups. The mean consumption of morphine in the periods 0 to 24 h and 24 to 48 h from the end of surgery was 10 mg (interquartile range, 5.8–19.5 mg) and 9.5 mg (4.5–20.0 mg) in Group 1, 8.5 mg (interquartile range, 4.8–19.5) and 6.0 mg (3.0–10.5 mg) in Group 2, and 15.5 mg (interquartile range, 6.0–23.0 mg) and 8.0 mg (3.0–11.0 mg) in Group 3. We did not find significant differences in sedation or other side effects (abdominal distention and itching were not associated with a large consumption of morphine) (Table 3).

	Discussion

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The advantages of combining ondansetron and droperidol are based on their different mechanisms of antiemetic activity and their efficacy when used in combination. Pueyo et al. (7) studied women undergoing intraabdominal surgery (75% gynecological). Antiemetic therapy was given in a randomized, double-blinded manner at the induction of anesthesia and 12 hours later. There were four groups: placebo then placebo; droperidol 2.5 mg then droperidol 1.25 mg; ondansetron 4 mg then placebo; and droperidol 2.5 mg plus ondansetron 4 mg then droperidol 1.25 mg. Ondansetron and droperidol were superior to placebo, but the combination was significantly more effective than monotherapy. The overall incidence of PONV up to 48 hours after surgery was 8% in the combination group, compared with 40% and 44% in the droperidol and ondansetron groups, respectively. McKenzie et al. (14) also demonstrated the benefits of ondansetron/droperidol combination therapy compared with monotherapy. Others have confirmed this phenomenon (15), but it is not a consistent finding. For example, a combination of ondansetron and droperidol was not superior to droperidol alone for the prevention of PONV in children undergoing strabismus surgery (16) or in adults after major gynecological surgery (17).

We must remember that when droperidol was used as an adjunct to PCA or in repeated doses, it was as effective as ondansetron (7,18,19). So, as other authors have suggested, we recommended giving a subsequent prophylactic dose of droperidol to further sustain the decrease in PONV found in the first hours of the postoperative period. We used a 1.25-mg dose of droperidol because it is an effective dose, and at this dose the incidences of dysphoria, restlessness, drowsiness, and sedation do not differ compared with ondansetron (15,20,21). The smaller effective dose of ondansetron is 4 mg in the prophylaxis of PONV (22). The efficacy of the combination, found in this study, is less than in other studies with similar methodology. Pueyo et al. (7) found an incidence of PONV in the combination group of only 8%, and in this study it was 20%. The only differences between the trials were the administration of intrathecal morphine and a smaller dose of droperidol at the induction in this study.

McKenzie et al. (23) were the first to demonstrate that the combination of ondansetron and dexamethasone was better than ondansetron alone in women undergoing general anesthesia for major gynecological surgery. Patients received ondansetron 4 mg plus saline or plus dexamethasone 8 mg. The complete response, defined as no emesis and no need for antiemetic rescue during the 24-hour postoperative period, occurred in 38% and 58% of the patients, respectively (P = 0.048).

López-Olaondo et al. (8) studied women undergoing major gynecological surgery. Antiemetics were given at the induction of anesthesia: placebo, ondansetron 4 mg, dexamethasone 8 mg, or a combination of dexamethasone 8 mg and ondansetron 4 mg. Both ondansetron and dexamethasone were significantly better than placebo, but the combination was significantly more effective than all groups. The incidence of PONV at 24 hours was 48% in the ondansetron group and 40% in the dexamethasone group, compared with 80% in the placebo group. The incidence of PONV in the combination group was only 16%. We used an 8-mg dose because a quantitative systematic review of dexamethasone for the prevention of PONV recommended that dose (24). Moreover, recently there was a dose-range study of dexamethasone in women undergoing abdominal hysterectomy under epidural anesthesia who received epidural morphine for postoperative analgesia, and the authors recommended a 5-mg dose (25). We administered a single dose because the plasma elimination half-life of dexamethasone is approximately 4–4.5 hours, similar to that of other antiemetics usually administered in a single dose (26). Here, again, we found that the incidence of PONV in this combination group was more frequent than that in other studies with similar methodology. López-Olaondo et al. (8) found an incidence of 16%, and in our study it was 30%. In this case, the only difference was the administration of intrathecal morphine.

We have shown that the combination of ondansetron with dexamethasone or droperidol is better than the combination of dexamethasone with droperidol. There is only one study comparing this combination with others. It was performed in women undergoing major gynecological surgery. The authors concluded that the combination of granisetron with dexamethasone was more effective than the combination of dexamethasone with droperidol or metoclopramide (27).

The side effects of antiemetics may limit their use. Increased drowsiness and restlessness have been reported with large doses of droperidol, and headaches have been associated with the administration of ondansetron (28). The most frequent reported side effect of dexamethasone is perineal itching during IV administration. In this study, 39% of patients reported adverse events. Most of them were minor. The total incidence of adverse events (except PONV), including sedation, was similar in all groups. The dose of droperidol used in this study may explain why there was no difference in sedation among groups, although the small size of the groups could also be the cause. No patient complained of headache in our study, in spite of the incidence of headache associated with ondansetron and dural puncture because of intrathecal morphine. To avoid perineal itching with dexamethasone, we administered it, as well as the other antiemetics, after the induction of anesthesia. The most commonly reported adverse effect was abdominal distention, followed by itching; these were not associated with a large consumption of morphine.

In conclusion, the combination of ondansetron with droperidol or dexamethasone is significantly better than the combination of dexamethasone with droperidol in the prophylaxis of PONV in women undergoing gynecological surgery who received intrathecal opioids and IV PCA morphine for the management of postoperative pain.

	References

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Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999