Intravenous Local Anesthetic Compared With Intraperitoneal Local Anesthetic in Laparoscopic Colectomy: A Double-blind Randomized Controlled Trial.

INTRODUCTION: Controlling perioperative pain is essential to improving patient experience and satisfaction following surgery. Traditionally opioids have been frequently utilized for postoperative analgesia. Although they are effective at controlling pain, they are associated with adverse effects, including postoperative nausea, vomiting, ileus, and long-term opioid dependency.Following laparoscopic colectomy, the use of intravenous or intraperitoneal infusions of lidocaine (IVL, IPL) are promising emerging analgesic options. Although both techniques are promising, there have been no direct, prospective randomized comparisons in patients undergoing laparoscopic colon resection. The purpose of this study was to compare IPL with IVL. METHODS: Double-blinded, randomized controlled trial of patients undergoing laparoscopic colonic resection. The 2 groups received equal doses of either IPL or IVL which commenced intra-operatively with a bolus followed by a continuous infusion for 3 days postoperatively. Patients were cared for through a standardized enhanced recovery after surgery program. The primary outcome was total postoperative opioid consumption over the first 3 postoperative days. Patients were followed for 60 days. RESULTS: Fifty-six patients were randomized in a 1:1 fashion to the IVL or IPL groups. Total opioid consumption over the first 3 postoperative days was significantly lower in the IPL group (70.9 mg vs 157.8 mg P < 0.05) and overall opioid consumption during the total length of stay was also significantly lower (80.3 mg vs 187.36 mg P < 0.05. Pain scores were significantly lower at 2 hours postoperatively in the IPL group, however, all other time points were not significant. There were no differences in complications between the 2 groups. CONCLUSION: Perioperative use of IPL results in a significant reduction in opioid consumption following laparoscopic colon surgery when compared to IVL. This suggests that the peritoneal cavity/compartment is a strategic target for local anesthetic administration. Future enhanced recovery after surgery recommendations should consider IPL as an important component of a multimodal pain strategy following colectomy.

Plasma Ropivacaine Concentrations Following Local Infiltration Analgesia in Total Knee Arthroplasty: A Pharmacokinetic Study to Determine Safety Following Fixed-Dose Administration.

BACKGROUND AND OBJECTIVES: The primary aim of this study was to examine the pharmacokinetics of ropivacaine in patients undergoing elective total knee arthroplasty with local infiltration analgesia as the primary analgesic method. We also sought to determine the incidence of biochemical toxicity through measurement of plasma ropivacaine concentrations over the first 24 hours postoperatively. METHODS: This was a prospective, observational study of 15 patients undergoing elective total knee arthroplasty. Local infiltration analgesia was administered by standard technique with 300 mg ropivacaine and epinephrine 5 µg/mL. Total ropivacaine concentrations were taken at specified time intervals in the 24 hours after tourniquet release and analyzed by liquid chromatography-mass spectrometry. RESULTS: Fifteen patients were enrolled into the study. The median peak ropivacaine concentration was 0.57 µg/mL, with a range of 0.32 to 0.88 µg/mL, and occurred between 6 and 24 hours. Age (P = 0.04), weight (P = 0.04), creatinine (P = 0.02), and female sex (P = 0.03) were important predictors of peak concentration. Age (P = 0.02), female sex (P = 0.01), and baseline α1 acid glycoprotein concentrations (P = 0.03) were important predictors for the area under the curve from a ropivacaine concentration versus time plot. CONCLUSIONS: The peak total ropivacaine concentration was below quoted toxic concentrations (2.2 µg/mL) in all patients. This peak occurred later than has previously been described in those undergoing neuraxial or peripheral nerve block, occurring between 6 and 24 hours. The influence of age, weight, and renal function on systemic ropivacaine concentration should be considered when planning local infiltration analgesia. Female sex is a factor that has not previously been associated with peak ropivacaine concentrations.