Out-of-plane ultrasound-guided paravertebral blocks improve analgesic outcomes in patients undergoing video-assisted thoracoscopic surgery

Corey Amlong, Moltu Guy, Kristopher M Schroeder, Melanie J Donnelly Department of Anesthesiology, University of Wisconsin Hospital and Clinics, Madison, WI, USA Purpose: Paravertebral blocks (PVBs) are a method of limiting postoperative pain for patients undergoing video-assisted thoracoscopic surgery (VATS). We began providing ultrasound-guided PVBs for patients undergoing VATS in the spring of 2011, using an out-of-plane approach. The aim of this study was to evaluate this practice change. Methods: Following institutional review board approval, we reviewed the charts of 114 patients undergoing VATS by one surgeon at our institution between January 2011 and July 2012. Of the 78 eligible patients, 49 patients received a PVB prior to surgery. We evaluated opioids administered in the perioperative period, pain scores, and side effects from pain medications. Results: Patients who received a preoperative PVB required fewer narcotics intraoperatively and during their hospital stay (P=0.001 and 0.011, respectively). Pain scores on initial assessment and in recovery were lower in patients who received a PVB (P=0.005), as were dynamic and resting pain scores at 24 hours after surgery (P=0.003 and P<0.001, respectively). Patients receiving a PVB had fewer episodes of treated nausea both in the postanesthesia care unit (P=0.004) and for the first 24 hours after surgery (P=0.001). These patients also spent less time in recovery (P=0.025) than the patients who did not receive a block. Conclusion: The current study suggests improved outcomes in patients who underwent VATS with a preoperative PVB. All variables showed a trend toward improved results in patients who obtained a preoperative PVB. Keywords: nerve blocks, video-assisted thoracoscopic surgery, anesthesia, pai

Lipid-free fluoropolymer-based propofol emulsions and lipid reversal of propofol anesthesia in rats

Background: Propofol, as a lipid-based emulsion, is effective at inducing anesthesia. It does, however, suffer from several drawbacks, including microbial growth, hyperlipidemia, and pain on injection. In this study, the authors examined the ability of four lipid-free propofol nanoemulsions to induce anesthesia in rats and tested whether a subsequent lipid bolus would accelerate emergence from anesthesia. Methods: The authors administered five formulations of propofol intravenously to six rats, delivering five different doses five times each, in a repeated-measures randomized crossover design and measured time to loss and recovery of righting reflex. The formulations included (1) Diprivan (AstraZeneca, United Kingdom); (2) L3, incorporating a semifluorinated surfactant plus egg lecithin; (3) B8, incorporating a semifluorinated surfactant only; (4) F8, incorporating a semifluorinated surfactant plus perfluorooctyl bromide; and (5) L80, incorporating egg lecithin only. In a second phase of the study, the authors administered a lipid bolus immediately after a dose of B8 or Diprivan. Results: All formulations except L80 impaired the righting reflex without apparent toxic effects. The authors estimated the threshold dose for induction by determining the x-intercept of the linear regression between time to recovery versus log dose. Threshold doses ranged from 5.8 (95% CI, 5.5 to 6.2) to 8.6 (95% CI, 7.2 to 10.2) mg/kg. A 15 ml/kg lipid bolus resulted in an accelerated clearance. Conclusions: Three of the four novel lipid-free fluoropolymer-based formulations showed efficacy in producing anesthesia, which was comparable to that of Diprivan, and a lipid bolus hastened recovery. These novel propofol formulations have the potential to avoid complications seen with the existing lipid-based formulation.2031-01-0