Discontinued group (n=33) Analysis of the risk factor of discontinuation of fentanyl based intravenous patient-controlled analgesia after lumbar spinal fusion surgery Shigehiko Urabe1, Yoshiaki Terao1, Shozo Tominaga1, Natsuko Oji1, Makito Oji1, Makoto Fukusaki1, Tetsuya Hara2 1Department of Anesthesia, Nagasaki Rosai Hospital, Sasebo, Nagasaki, 2Department of Anesthesiology, Nagasaki University School of Medicine, Nagasaki, Nagasaki Japan. BACKGROUND Postoperative period ・Metoclopramide 10mg was injected intravenously when the patients reported PONV and required the antiemetics during postoperative period. The nursing staffs discontinued FIPCA when the patients reported intolerable PONV and required FIPCA discontinuation after metoclopramide administration. 　We compared these parameters between the group of patients continued with FIPCA (C group) and the group of patients discontinued with FIPCA (D group) . Statistical Analysis ・Intergroup comparisons were performed with Mann-Whitney U test or chi-square test. Multivariate logistic regression analysis for discontinuation of FIPCA were performed. A p value < 0.05 was considered statistically significant. MATERIALS and METHODS Table 1 　Background data on each group of patients Table 3 Multivariate logistic regression analysis Explanatory variables p Sex 0.048 Antiemetics use 0.012 Smoking 0.082 Intraoperative fentanyl dosage (㎍/kg) Fentanyl based intravenous patient-controlled analgesia (FIPCA) is a well-established for postoperative pain control in patients undergoing lumbar spinal fusion surgery. However, fentanyl increases the incidence of postoperative nausea and vomiting (PONV). PONV is a major risk factor of unexpected discontinuation of FIPCA because of intolerable discomfort. Continued group Discontinued group p Number 247 33 Age (years) 67 (60, 85) 76 (62, 82) 0.007 Male / Female (n) 157 / 90 13 / 20 0.008 Height (cm) 160 (153, 168) 155 (149, 160) 0.016 Weight (kg) 60 (51, 70) 52 (48, 66) 0.040 Standard weight (kg) 56 (51, 62) 53 (49, 56) Body mass index (kg/㎥) 23 (21, 26) 22 (21, 26) 0.330 Smoker / Non smoker (n) 141 / 106 11 / 22 0.010 Intraoperative fentanyl dosage (㎍/kg) 6.7 (4.6,8.6) 5.3 ( 4.6,8.4) 0.442 Postoperative fentanyl administration rate (㎍/kg/h) 6.7 (4.6, 8.6) 5.3 (4.6, 8.4) Inhalation anesthesia / Total intravenous anesthesia (n) 21 / 12 0.474 DISCUSSION PURPOSE ・ Kaufmann et al. found that adding metoclopramide to morphine did not influence the incidence or severity of emesis. However, Silverman et al. studies have found that the addition of droperidol (0.05–0.2 mg / ml) to morphine PCA has reduced the incidence of nausea and vomiting 1). ・ De Oliveira Jr et al. demonstrated that 10 mg i.v. metoclopramide is effective to prevent PONV in patients having surgical procedures under general anaesthesia 2). ・ Apfel et al showed that reduction of PONV was not significantly associated with reduction of morphine equivalents; however, it was associated with a reduction in pain intensity 3). ・ Schaub et al concluded that droperidol at doses of 1mg or less is antiemetic, and that adverse drug reactions are likely to be dose-dependent, there is an argument to stop using doses above 1 mg 4). The aim of this retrospective study is to identify the risk factors of unexpected discontinuation of FIPCA after lumbar spinal fusion surgery. MATERIALS and METHODS Patients ・Total 280 patients administered with FIPCA after lumbar spinal fusion surgery from January to December 2015. Anesthesia ・The anesthesiologists chose the manners of anesthesia, antiemetics and FIPCA according to clinical requirements. The following information was obtained from the medical chart of each patient: patient characteristics types of general anesthesia the fentanyl dosage used during anesthesia the concentration of fentanyl in FIPCA types of antiemetics (metoclopramide 10mg , droperidol 1.25-2.5 mg or no administration) mixed in FIPCA and administrated during anesthesia. RESULTS ・Table 1 There were significant differences in age, sex, height, weight, standard weight and number of smokers between two groups. There were no significant differences in types of general anesthesia, the dose of fentanyl during anesthesia and the concentration of fentanyl in FIPCA between two groups. ・Table 2 In the FIPCA continued group, patients receiving droperidol were significantly more than those who did not receive antiemetics.This means that droperidol showed a significant antiemetic effect, compared with no administration of antiemetics. ・Table 3 Multivariate logistic regression analysis showed that female gender and no administration of the antiemetics were independent risk factors for unexpected discontinuation of FIPCA. Our data showed that droperidol may be effective against PONV under FIPCA administration after lumbar spinal fusion Surgery. Our data was consistent with the above argument in some respects. Table 2 Comparison of types of antiemetics administered during anesthesia between two groups Continued group (n=247) Discontinued group (n=33) p Metoclopramide / droperidol / unused (n) 61 / 121 / 65 8 / 10 / 15 0.052 Metoclopramide / droperidol (n) 61 / 121 8 / 10 0.352 Metoclopramide / unused (n) 61 / 65 8 / 15 0.228 Droperidol / unused (n) 121 / 65 10 / 15 0.015 CONCLUSIONS This study showed that female gender and no administration of the antiemetics were independent risk factors for unexpected discontinuation of FIPCA. Low dose of droperidol may be effective against PONV under FIPCA administration after lumbar spinal fusion surgery. References: 1, Anaesthesia; 52: 770-775. 1997. 2, British Journal of Anaesthsia; 109; 688-697. 2012 3, PAIN; 154: 677-689. 2013 4, European Journal of Anaesthesiology; 29: 286-294. 2012