Plasma concentrations of ropivacaine following ultrasound-guided or nerve-stimulator-guided femoral nerve block: A prospective randomised study

A single center descriptive study of local anesthetic dose in knee arthroplasty: Was there evidence of local anesthetic systemic toxicity?

STUDY OBJECTIVE

Describe dosing of local anesthetic when both a periarticular injection (PAI) and peripheral nerve block (PNB) are utilized for knee arthroplasty analgesia, and compare the dosing of local to suggested maximum dosing, and look for evidence of local anesthetic systemic toxicity (LAST).

DESIGN

A single center retrospective cohort study between May 2018 and November 2022.

SETTING

A major academic hospital.

PATIENTS

Patients who had both a PAI and PNB while undergoing primary, revision, total, partial, unilateral, or bilateral knee arthroplasty.

INTERVENTIONS

None.

MEASUREMENTS

Calculate the dose of local anesthetic given via PAI, PNB, and both routes combined as based on lean body weight and compare that to the suggested maximum dosing. Look for medications, clinical interventions, and critical event notes suggestive of a LAST event.

MAIN RESULTS

There were 4527 knee arthroplasties where both a PAI and PNB were performed during the study period. When combining PAI and PNB doses, >75% of patients received more than the suggested maximum dose of 3 mg/kg lean body weight. The median local anesthetic dosing over the study period, 4.4 mg/kg (IQR 3.5,5.9), was 147% of the suggested maximum dose (IQR 117,197). There was no conclusive evidence of LAST among any of the patients in the study.

CONCLUSIONS

Over the course of our study, we had 4527 knee arthroplasties with a median PAI and PNB local anesthetic dose that was 147% of the suggested maximum without any clear clinical evidence of a LAST event.

Antitumor Proliferation and Related Mechanism of Ultrasound Irradiation Combined with Safflower Yellow

Ultrasound irradiation is now the best method for evaluating benign and malignant tumor nodules. Chemotherapy has always played an important role in the treatment of malignant tumors. With the large-scale application of chemotherapy drugs, the problem of multidrug resistance of tumors has become more and more prominent, which has become one of the difficulties in tumor chemotherapy. This study mainly explores the antitumor proliferation and related mechanisms of ultrasound irradiation combined with safflower yellow. The breast cancer cell line 4T1 derived from BALB/c mice was selected. BALB/c is an albino laboratory mouse, which, like many commonly used sublines, originated from Mus musculus. BALB/c mice have been bred for more than 200 generations in research institutions around the world and are widely used in animal experiments in immunology and physiology. When the cell proliferation reached 80%-90% of the bottom area of the culture flask, it was resuspended, passaged, frozen, and resuscitated according to experimental needs. The 4T1 breast cancer cell line was cultured by conventional methods. 4T1 breast cancer cells in the logarithmic proliferation phase were collected. After 0.25% was digested with pancreatin, it was washed twice with PBS to adjust the concentration to 1 × 107/mL. A 0.1 mL tumor cell suspension was subcutaneously inoculated on the edge of the mouse chest, thereby establishing a breast cancer model of BALB/c mice. After 6-15 days, the tumor volume grew rapidly and became larger. When the length of the tumor is 2.5 × 2.5, the modeling is successful. Ultrasound-targeted microbubble destruction technology, as a novel drug delivery method with high efficiency and low toxicity, can form transient pores (sonoporation effect) on the cell surface, widen the intercellular space, and increase the membrane permeability, and thus effectively. The transport of drugs, genes, proteins, etc., is promoted to target organs and tissues. Tumor-forming mice were randomly divided into the following four groups: control group, safflower yellow group, ultrasound irradiation group, and ultrasound irradiation combined with safflower yellow group. From the second day of inoculation to the end of the experiment, the body weight of the mice successfully inoculated with 4T1 cells was measured every day; from the 5th day, tumors in each group were calculated body volume and tumor inhibition rate (TIR) of each group. The combined treatment group has a higher tumor inhibition rate than the ultrasound irradiation group, and the difference is statistically significant (P < 0.05). Ultrasound irradiation combined with safflower yellow pigment can effectively inhibit tumor proliferation, maintain, or even improve the efficacy of chemotherapy, thereby improving the patient's tolerance to chemotherapy.

Population pharmacokinetics of ropivacaine used for local infiltration anaesthesia during primary total unilateral and simultaneous bilateral knee arthroplasty

BACKGROUND

Ropivacaine is commonly used in local infiltration anaesthesia (LIA) as pain management after total knee arthroplasty (TKA). Although considered safe, no studies evaluated the pharmacokinetics of high-dose ropivacaine infiltration in simultaneous bilateral TKA.

METHODS

We studied 13 patients undergoing unilateral and 15 undergoing bilateral TKA. Standard LIA technique was used with ropivacaine 0.2%, 200 ml (400 mg) injected peri-articularly in each knee. Free and total plasma concentrations of ropivacaine were measured within 24 h using liquid chromatography-mass spectrometry. A population pharmacokinetic model was built using non-linear mixed-effects models.

RESULTS

Peak free ropivacaine concentration was 0.030 (0.017-0.071) μg ml^-1 (mean [99% confidence interval]) vs 0.095 (0.047-0.208) μg ml^-1, and peak total ropivacaine concentration was 0.756 (0.065-1.222) μg ml^-1vs 1.695 (0.077-3.005) μg ml^-1 for unilateral and bilateral TKA, respectively. The pharmacokinetics was ascribed a one-compartment model with first-order absorption. The main identified covariates were protein binding, allometrically scaled body weight on clearance and volume, and unilateral or bilateral surgery on volume.

CONCLUSIONS

This is the first study to investigate the pharmacokinetics of free and total ropivacaine after unilateral and bilateral TKA. A population model was successfully built and peak free ropivacaine concentration stayed below previously proposed toxic thresholds in patients undergoing unilateral and bilateral TKA receiving LIA with high-dose ropivacaine.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04702282.

Regional anesthesia to ameliorate postoperative analgesia outcomes in pediatric surgical patients: an updated systematic review of randomized controlled trials

Regional anesthesia is becoming increasingly popular among anesthesiologists in the management of postoperative analgesia following pediatric surgery. The main objective of this review was to systematically evaluate the last 5 years of randomized controlled trials on the role of regional anesthesia techniques in alleviating postoperative pain associated with various pediatric surgical procedures. Forty studies on 2,408 pediatric patients were evaluated. The majority of the articles published from 2013 to 2017 reported that the use of regional anesthesia minimized postoperative pain and reduced opioid consumption. Only a few surgical procedures (cholecystectomy, inguinal hernia repair, and non-laparoscopic major abdominal surgery) reported no significant difference in the postoperative pain relief compared with the standard anesthetic management. The growing number of randomized controlled trials in the pediatric literature is very promising; however, additional confirmation is needed to reinforce the use of specific regional anesthesia techniques to provide optimal postoperative pain relief for a few surgical procedures (reconstructive ear surgery, chest wall deformity, hypospadias, umbilical hernia, cleft palate repair) in pediatric patients. More randomized controlled trials are needed to establish regional anesthesia as an essential component of postoperative analgesia management in children.