A Double-blinded, Randomized, Placebo Controlled Study of the Effect a Small Dose of Ketamine has on Postoperative Pain of Sevoflurane-remifentanil Anesthesia / 대한마취과학회지

BACKGROUND: Remifentanil is a useful and relatively safe opioid, but acute tolerance to it frequently develops, as patients who have received remifentanil based anesthesia often suffer postoperative hyperalgesia.This study investigated whether a small dose of ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, can attenuate postoperative pain suffered with remifentanil anesthesia. METHODS: 32 patients who were scheduled to undergo laparoscopic cholecystectomy were randomly assigned to two groups: a ketamine group (group K) and a control group (group C).All patients were given remifentanil by target controlled infusion (TCI) to the effect site (concentrations:4.0-6.0 ng/ml).Just before incision patients in group K received 0.15 mg/kg ketamine intravenously and patients in group C received the same volume, but only of normal saline.Pain scores measured by Numerical Rating Scale (NRS) and additional use of analgesics were immediately recorded by a blinded investigator at the post-anesthesia care unit (PACU) and general ward up to 24 hours after surgery. RESULTS: The average NRS scores upon arrival to PACU, 5, 10, 15 and 30 min in PACU, and 5 hours after discharge from PACU were significantly lower in group K than group C.The frequency of additional analgesics use was also significantly lower in group K. CONCLUSIONS: It is suggested that a small dose of ketamine attenuates the postoperative pain felt with remifentanil anesthesia. This finding also suggests that ketamine may decrease the possible acute tolerance developed with remifentanil anesthesia.

Investigation of Orphanin FQ-stimulated 35SGTPgammaS Binding in the Whole Brain of Mice: Does Orphanin FQ Have Anti-opioid Effect in the Level of Receptor-ligand Interaction and 35SGTPgammaS Activation? / 대한마취과학회지

BACKGROUND: This study was examined whether or not the orphanin FQ (OFQ)-stimulated [35S]GTPgammaS activity interact with DAMGO in the whole brain of mice. METHODS: ICR mice (male, n = 20, 20-25 g) were euthanized for the membrane preparations. In the agonist-stimulated [35S]GTPgammaS binding dose-response curves by OFQ, Ro-64-6198 and DAMGO, the EC50 (effective concentration 50, nM) and maximum stimulation (% over basal) were determined in the presence or absence of J-113397 (10 nM), a NOP (nociceptin-opioid peptide) receptor antagonist. OFQ (1micrometer), Ro-64-6198 (10micrometer), DAMGO (10micrometer) and their combination cocktail were used to determine the interaction between the NOP and MOP (micron-opioid peptide) receptor. RESULTS: The values of EC50 and maximum stimulation of [35S]GTPgammaS binding were as follows: OFQ (9.2 +/- 0.2 nM/17.9 +/- 0.1%), Ro-64-6198 (143.5 +/- 0.5 nM/18.1 +/- 0.4%), and DAMGO (680.6 +/- 0.7 nM/18.1 +/- 0.5%). J-113397 produced a 8.7 and 7.1 fold rightward shifting in the OFQ and Ro-64-6198-stimulated [35S]GTPgammaS binding dose-response curve respectively, but not in the DAMGO. OFQ combined with DAMGO-stimulated [35S]GTPgammaS binding had an additive effect, but not in the OFQ combined with Ro-64-6198. CONCLUSIONS: OFQ, Ro-64-6198 and DAMGO-stimulated [35S]GTPgammaS binding in the brain of mice has receptor selectivity. The [35S]GTPgammaS stimulation of OFQ and DAMGO had an additive effect rather than an anti-opioid effect on the level of intracellular signal transduction through agonist-stimulated [35S]GTPgammaS bindings.

The Maternal and Neonatal Effect of Remifentanil in General Anesthesia for Cesarean Section

BACKGROUND: In case of general anesthesia for cesarean section, giving remifentanil has been described, but its maternal and neonatal effects and safety have not been investigated by a controlled study. METHODS: 20 healthy women undergoing elective cesarean section under general anesthesia at term were allocated randomly to receive remifentanil as effect site concentration of 3.0 ng/ml (R group, n = 10) and same amount of normal saline (C group, n = 10) just before endotracheal intubation. Each group was assessed for bispectral index (BIS), blood pressure, and heart rate at preinduction, arrival to target concentration, intubation, and 1 and 3 minutes after intubation and delivery. Neonatal effect was assessed by Apgar score at 1 and 5 minutes. RESULTS: The BIS of remifentanil group was lower than that of control group at 1 min after intubation (P < 0.05). The systolic blood pressure of remifentanil group were lower than those of control group at immediately after intubation (P < 0.05) and 1 min after intubation (P < 0.01). There were no significant differences in heart rate between two groups. CONCLUSIONS: We found that infusing remifentanil just before tracheal intubation was effective and safe to both mother and neonate.