Is breakthrough pain better managed by adding programmed intermittent epidural bolus to a background infusion during labor epidural analgesia? A randomized controlled trial.

Background: Breakthrough pain (BTP) is a common problem during labor analgesia. Programmed intermittent epidural bolus (PIEB) has demonstrated superior to background epidural infusion (BEI) concerning BTP, but the effect of combining both modes remains unknown. We hypothesized that this combination could reduce BTP incidence.

Oxidative stress induced by tert-butyl hydroperoxide causes vasoconstriction in the aorta from hypertensive and aged rats: role of cyclooxygenase-2 isoform.

We analyzed the mechanisms involved in the effect of tert-butyl hydroperoxide (t-BOOH) in isolated aortic rings with and without endothelium from normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) at 6, 18, and 24 months of age. t-BOOH (1 microM-10 mM) induced concentration-dependent contractions that were scarcely modified by aging and potentiated in SHR and by endothelium removal. The nitric oxide synthase and prostacyclin synthase inhibitors N(G)-nitro-L-arginine methyl ester (100 microM) and tranylcypromine (100 microM), respectively, increased both basal tone and the t-BOOH-induced contractions in intact segments from WKY, with these effects not observed in SHR.