TITLE: NAPROXEN IMPROVES POST CESAREAN ANALGESIA AFTER SPINAL MORPHINE

AUTHORS: Pamela J. Angle, MD, FRCPC, DABA, Stephen Halpern, MD FRCPC, Barbara Leighton, MD DABA, Donna Wilson, RN, K. Gnanendran, MD FRCPC, Jean Kronberg, MD FRCPC
AFFILIATION: Sunnybrook and Women's College Health Sciences Center, Toronto, Ontario, Canada.

INTRODUCTION: Few studies have examined the efficacy of regularly-dosed non-steroidal anti-inflammatory drugs after cesarean section.¹ We performed a prospective randomized double blind placebo-controlled trial to examine the efficacy of adding naproxen to conventional pain therapy after spinal morphine.
METHODS: 80 ASA I-II parturients scheduled for elective cesarean section were given a standardized spinal anesthetic (heavy marcaine 0.75%, 1.2-2.0cc; fentanyl 10-20mcg; preservative free morphine 0.2mg) and randomized into 2 treatment groups at the end of surgery. Group 1 received inactive placebo every 12 hours; Group 2 received naproxen, 500mg (suppository) followed by oral naproxen sodium, 550mg every 12 hours (6 doses total). Interviews using pre-tested questionnaires were used to assess pain type (incision, uterine cramping, gas) and pain severity with rest and sitting (10cm VAS scale) as well as interval worst pain scores (numeric rating score 0- 10). Interval overall pain relief was measured regularly using a 6 point scale. Interval analgesic requirements, time to first analgesic request (TTFA) and maternal and neonatal side effects were assessed. Primary outcome was incisional pain on sitting at 48hours (VAS). Secondary outcomes included: VAS pain scores; analgesic requirements; quality of analgesia; and side effects. Statistical analysis included parametric and non-parametric tests as appropriate. A p value <0.05 was considered significant.
RESULTS: Overall pain relief (Fig.1) differed significantly over 0- 24 (p<0.001) and 25-48 hours(p<0.001, Mann Whitney U test) with an increase in very good and excellent pain relief ratings in Group 2 despite a significant reduction in narcotic use (oral codeine equivalents (Group l vs. Group 2) Day 1: 165mg17SEM vs. 62mg ±14 SEM, p=0.0000; Day 2: 231mg±18SEM vs. 135mg±18 SEM, p<0.001; Day 3: 215mg±28 SEM vs. 115mg±20SEM, p<0.01). Acetaminophen requirements were similarly reduced. TTFA request differed significantly with 83% (58% <12hours) of Group 1 receiving additional analgesia within 24hours compared with 51% (24% <12hrs) in Group 2. VAS scores for uterine cramping were reduced in Group 2 at 24 hours (25.4±3.1 SEM vs. 11.9±3.1 SEM, p<0.01) and 36hours (35.8±4.8 SEM vs. 13.8±3.7 SEM, p<0.001) as well as for gas pain at 36hours (27.8±4.8 SEM vs. 14.4±3.9 SEM). No significant difference in side-effects was found. 15% (5/33) of Group 2 left hospital early (<72hours) compared with 3% (1/40) in Group 1.
CONCLUSION: Addition of regularly dosed naproxen im-proves overall pain relief on days 1 and 2 after cesarean section with spinal morphine as well as recing interval analgesic requirements.
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