Analgesic efficacy of continuous wound infiltration compared with continuous intravenous fentanyl after gynaecological surgery: a non-inferiority, randomised controlled trial.

OBJECTIVE: The present trial aimed to prove the non-inferiority of the analgesic efficacy of continuous wound infiltration (CWI) to that of continuous intravenous fentanyl (IV) and to compare the safety of the two methods. METHODS: This trial was a prospective, single-centre, two-arm, non-inferiority, randomised controlled trial. Patients participating in the trial were randomised to a CWI group or an IV group. The VAS (visual analogue scale), additional analgesic usage and side effects were then compared between the groups. RESULTS: In total, 61 patients were enrolled; two in CWI were excluded, leaving 59 (30 in the CWI group and 29 in the IV group) for analysis. The difference in the VAS score at 24 h (CWI group - IV group) was -3.2 (95% confidence interval [CI] -14.7 to 8.2), which was less than the non-inferiority margin of 15. The mean amount of total fentanyl use at postoperative hour 48 was 1395 (95% CI 886-1903) µg in the CWI group and 3186 (95% CI 2716-3658) µg in the IV group. The amount of other analgesics and the incidence of adverse effects did not differ significantly between the groups. CONCLUSION: CWI was non-inferior to IV in terms of its analgesic effect, and has an opioid sparing effect in open gynaecological surgery.

Management of labor and delivery in myasthenia gravis: A new protocol.

AIM: Pregnancy with myasthenia gravis (MG) is known to be associated with an increased cesarean section rate, presumably due to maternal fatigue during labor. Although epidural labor analgesia (ELA) appears to be a good option for circumventing maternal fatigue, a protocol for managing MG deliveries has not been established. This study, based on a review of our case series, aimed to evaluate the validity of our management protocol for maternal MG, in which ELA is used depending on MG severity. METHODS: Parturients with systemic muscle weakness or worsening symptoms were classified as Category A (A), and those without symptoms were classified as Category B (B). In A, ELA was given at the onset of labor. Immediate vacuum delivery was done once the fetal head descended to station +2. For B, spontaneous vaginal delivery was chosen. The duration, blood loss, fetal weight, Apgar score and MG symptoms on post-partum day (PPD) 1, 14 and 30 were recorded. RESULTS: Six patients were enrolled. Four were classified in A, and two were classified in B. No adverse events occurred during labor. Transvaginal delivery was successfully achieved in all the patients. Symptoms of MG were well-controlled. MG symptoms were stable on PPD 1 in all the patients although two patients complained of worsening symptoms after PPD 14. CONCLUSION: Women with MG can safely undergo spontaneous or operative vaginal delivery. ELA is a good option for circumventing the effects of maternal fatigue on delivery. Our protocol may lower the cesarean section rate in maternal MG.

Valproate attenuates the development of morphine antinociceptive tolerance.

Morphine is a potent opioid analgesic. Repeated administration of morphine induces tolerance, thus reducing the effectiveness of analgesic treatment. Although some adjuvant analgesics can increase morphine analgesia, the precise molecular mechanism behind their effects remains unclear. Opioids bind to the mu opioid receptor (MOR). Morphine tolerance may be derived from alterations in the intracellular signal transduction after MOR activation. Chronic morphine treatment activates glycogen synthase kinase 3ß (GSK3ß), whose inhibition diminishes morphine tolerance. Valproate is widely prescribed as an anticonvulsant and a mood stabilizer for bipolar disorders because it increases the amount of γ-aminobutyric acid (GABA) in the central nervous system. Although the activation of GABAergic neurons may be responsible for the chief pharmacologic effect of valproate, recent studies have shown that valproate also suppresses GSK3ß activity. We examined the effect of valproate on the development of morphine antinociceptive tolerance in a mouse model of thermal injury. Mice were treated with morphine alone or with morphine and valproate twice daily for 5 days. The resulting antinociceptive effects were assessed using a hot plate test. While mice treated with morphine developed tolerance, co-administration of valproate attenuated the development of tolerance and impaired the activation of GSK3ß in mice brains. Valproate alone did not show analgesic effects; nevertheless, it functioned as an adjuvant analgesic to prevent the development of morphine tolerance. These results suggest that the modulation of GSK3ß activity by valproate may be useful and may play a role in the prevention of morphine tolerance.

BiP, an endoplasmic reticulum chaperone, modulates the development of morphine antinociceptive tolerance.

Morphine is a potent analgesic, but the molecular mechanism for tolerance formation after repeated use is not fully understood. Binding immunoglobulin protein (BiP) is an endoplasmic reticulum (ER) chaperone that is central to ER function. We examined knock-in mice expressing a mutant BiP with the retrieval sequence deleted in order to elucidate physiological processes that are sensitive to BiP functions. We tested the thermal antinociceptive effect of morphine in heterozygous mutant BiP mice in a hot plate test. Paw withdrawal latencies before and after a single administration of morphine were not significantly different between the wild-type and mutant BiP mice. Repeated morphine administration caused the development of morphine tolerance in the wild-type mice. The activation of glycogen synthase kinase 3b (GSK-3b) was associated with morphine tolerance, because an inhibitor of GSK-3ß prevented it. On the other hand, the mutant BiP mice showed less morphine tolerance, and the activation of GSK-3b was suppressed in their brain. These results suggest that BiP may play an important role in the development of morphine tolerance. Furthermore, we found that a chemical chaperone which improves ER protein folding capacity also attenuated the development of morphine tolerance in wild-type mice, suggesting a possible clinical application of chemical chaperones in preventing morphine tolerance.

Buprenorphine activates mu and opioid receptor like-1 receptors simultaneously, but the analgesic effect is mainly mediated by mu receptor activation in the rat formalin test.

Buprenorphine is a mixed opioid receptor agonist-antagonist. Recently, buprenorphine was reported to act as an agonist to opioid receptor like-1 (ORL1) receptor. In the present study, we examined the role of spinal and supraspinal mu receptors and spinal and supraspinal ORL1 receptors in producing an analgesic effect by intrathecal (i.t.), intracerebroventricular (i.c.v.), or i.p. administration of buprenorphine in the rat formalin test. Male rats were prepared with i.t. catheters or i.c.v. injection cannulas. The paw formalin injection (50 microl of 5% formalin) induces biphasic flinching (phase 1, 0-6 min; phase 2, 10-60 min) of the injected paw. Buprenorphine, naloxone (a mu-opioid receptor antagonist), or (1-[(3R,4R)-1-cyclooctylmethyl-3-hydroxymethyl-4-piperidyl]-3-ethyl-1,3-dihydro-2H-benzimidazol-2-one (J113397) (an ORL1 receptor-selective antagonist) was administered i.t., i.c.v., or i.p.. Intrathecal, i.c.v., or i.p. injection of buprenorphine produces an analgesic effect in a dose-dependent manner. The effect of i.c.v. buprenorphine was antagonized by i.c.v. naloxone or i.c.v. J113397, and the effect of i.t. buprenorphine was antagonized by i.t. naloxone or i.t. J113397. The effect of i.p. buprenorphine was antagonized by i.p. or i.t. naloxone but not by i.c.v. naloxone. The analgesic effect of i.p. buprenorphine was enhanced by i.p. J113397 or i.c.v. J113397. Intraperitoneal, but not i.t. or i.c.v., buprenorphine decreased the number of Fos-like immunoreactivity positive neurons in the L4-L5 spinal dorsal horn. These data indicated that buprenorphine affects nociceptive processing by acting at both supraspinal and spinal mu and ORL1 receptors. The analgesic effect of systemically administered buprenorphine was suppressed by the concomitant activation of supraspinal ORL1 receptor.

Anti-hyperalgesic effects of intrathecally administered neuropeptide W-23, and neuropeptide B, in tests of inflammatory pain in rats.

Neuropeptide W-23 (NPW23) is an endogenous ligand of both GPR7 and GPR8, and neuropeptide B (NPB) is an endogenous ligand of GPR7. GPR7 mRNA has been detected in regions of the cortex, the hippocampus, the hypothalamus, and the spinal cord in the rat, but GPR8 has not been found in rodents. GPR7 and GPR8 receptors have structural features in common with both opioid and somatostatin receptors. The effects of intrathecal (i.t.) application of NPW23 and NPB were tested in two inflammatory pain models (plantar injection of formalin or carrageenan) and two thermal nociceptive tests (52.5 degrees C and 50.5 degrees C hot plates) and one mechanical nociceptive test in the rat. I.t. injection of either NPW23 or NPB decreased the number of agitation behaviors induced by paw formalin injection and attenuated the level of mechanical allodynia, but not the level of thermal hyperalgesia, induced by paw carrageenan injection in a dose-dependent manner at a dose between 0.1 and 10 microg, significantly. The effects of either 10 microg of NPW23 or 10 microg of NPB were not antagonized by 10 microg of naloxone. I.t. injection of either NPW23 or NPB had no effect in both the 52.5 degrees C hot plate test or in the 50.5 degrees C hot plate tests at a dose between 1 and 100 microg. I.t. injection of either 10 microg of NPW23 or 10 microg of NPB had no effect in the mechanical nociceptive test. I.t. injection of either 10 microg of NPW23 or 10 microg of NPB significantly suppressed the expression of Fos-like immunoreactivity of the L4-5 spinal dorsal horn induced by paw formalin injection. These data suggest that both spinally-applied NPW23 and NPB suppressed the input of nociceptive information to the spinal dorsal horn, produced an analgesic effect in the formalin test, and attenuated the level of mechanical allodynia in the carrageenan test, and that either spinally applied NPW23 or spinally applied NPB had no effect in the physiological condition.

[Experience using an improved bronchial blocker (Phycon TCB bronchial blocker)].

We recently had opportunities to use an improved bronchial blocker (Phycon TCB bronchial blocker) in surgical patients who needed separation of the lungs and/or one-lung ventilation. This blocker provides a high torque control and can be easily manipulated into the desired site of the lungs. Our clinical experience shows that this blocker is useful particularly when the quick and sure separation of the lungs is crucial or when the insertion of a double-lumen tube is very difficult.