///2009 Abstract Details
2009 Abstract Details2019-08-03T15:55:31-06:00

Effect of a low dose of ketamine on postoperative pain after elective cesarean delivery according the presence of a preoperative Temporal Summation

Abstract Number: 111
Abstract Type: Original Research

Patricia M Lavand'homme MD, PhD1 ; Fabienne Roelants MD2

Introduction: Individual differences in endogenous pain modulation place individuals at greater risk to develop severe pain (Edwards R. Neurology 2005). Temporal summation (TS) the human phenomenon of a successively increased reaction to repeated nociceptive stimuli is an indirect method to evaluate CNS sensitization and nociceptive system hyperexcitability. The phenomenon relies on NMDA receptors activation (Eide PK, Eur J Pain 2000). The study assessed the effect of an antihyperalgesic dose of ketamine (KET) on postoperative pain after elective cesarean delivery (CD) according the presence of a preoperative TS.

Methods: Healthy parturients (>36 weeks) scheduled for elective CD underwent preoperative evaluation of TS on volar forearm as following: pricking pain score (VAS, 0-100) was recorded after single application and after the last application of a train of 10 mechanical stimuli (rate 1 Hz) with a 180 g von Frey filament. The difference between the two scores was calculated as mechanical TS. Patients were then randomly allocated to receive either IV KET 0.15 mg/kg or saline before surgical incision. Surgery was realized under spinal anesthesia and postoperative analgesia was provided by PCA morphine and systemic diclofenac. At 24h and 48h, postoperative pain scores (VAS, 0-100) at rest and movement, pain from uterine contractions and morphine use were recorded. For data analysis, patients were classified into 4 groups according to the presence or not of a preoperative positive TS (value > 15/100). Statistical analysis used ANOVA one way and posthoc tests, P <0.05 was significant.

Results: The groups did not differ for average age 325 years, nulliparas, repeated CD. Preoperative TS score was 3314 in TS+ group (n=17), 55 in TS- group (n=23), 2710 in KET TS+ group (n=14) and 45 in KET TS- group (n=22). At 24 h, TS+ patients displayed higher pain scores at movement than TS- patients and than TS+ patients who received preincisional KET (KET TS+) (Figure; (*) P <0.05 with TS+ group). At 48h, pain scores did not differ. PCA morphine use was similar among the groups.

Discussion: The presence of a positive TS is associated to enhanced postoperative pain during the first 24h. Those patients will benefit from preincisional KET antihyperalgesic dose. The present results may explain inconstant effects reported after KET administration (Sen et al, EJA 2005) and argue for individualizing medical treatments.

SOAP 2009