Systemic Ropivacaine Concentrations Following Local Infiltration Analgesia and Femoral Nerve Block in Older Patients Undergoing Total Knee Arthroplasty

Sigita Kazune; Inga Nurka; Matiss Zolmanis; Arturs Paulausks; Dace Bandere

doi:10.2147/LRA.S425353

Systemic Ropivacaine Concentrations Following Local Infiltration Analgesia and Femoral Nerve Block in Older Patients Undergoing Total Knee Arthroplasty

Local Reg Anesth. 2023 Sep 15:16:143-151. doi: 10.2147/LRA.S425353. eCollection 2023.

Authors

Sigita Kazune^{1

2}, Inga Nurka², Matiss Zolmanis², Arturs Paulausks^{3

4}, Dace Bandere^{4

5}

Affiliations

¹ Department of Anesthesiology and Intensive Care, Riga Stradins University, Riga, Latvia.
² Department of Anesthesiology, Hospital of Traumatology and Orthopedics, Riga, Latvia.
³ Laboratory of Finished Dosage Forms, Faculty of Pharmacy, Riga Stradins University, Riga, Latvia.
⁴ Baltic Biomaterials Centre of Excellence, Headquarters at Riga Technical University, Riga, Latvia.
⁵ Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Riga Stradins University, Riga, Latvia.

Abstract

Purpose: The study examined the pharmacokinetic profile of fixed formulation mixtures comprising 225 mg of ropivacaine for local infiltration analgesia with or without epinephrine, and femoral nerve block in older patients presenting for orthopedic surgery and explored potential influences of block type, age, and body weight on this profile.

Patients and methods: Twenty four patients scheduled for total knee arthroplasty were randomly assigned to three groups: femoral nerve block, local infiltration analgesia with epinephrine and local infiltration analgesia without epinephrine. Blood samples were collected at 10, 30, 60, and 120 min following the block and total plasma concentrations of ropivacaine were quantified by high performance liquid chromatography.

Results: The mean individual peak total plasma concentrations of ropivacaine in local infiltration analgesia with and without epinephrine, and femoral nerve block group were 0.334, 0.490 and 0.545 μg mL^-1 (p = 0.16). Local infiltration with epinephrine group had significantly lower plasma ropivacaine concentrations at 30, 60 and 120 minutes. The plasma ropivacaine concentrations exceeded 2.2 μg mL^-1 in one patient. Age, but not body weight, had a moderate correlation with peak plasma ropivacaine concentration (r = 0.37, p = 0.08).

Conclusion: Administration of a fixed 225 mg dose of ropivacaine for local infiltration analgesia with epinephrine and femoral nerve block results in plasma ropivacaine concentrations below the toxicity threshold, indicating their safety. The use of local infiltration analgesia with epinephrine provides a greater safety margin, as local infiltration analgesia without epinephrine may lead to ropivacaine concentrations associated with symptoms of local anesthetic toxicity.

Keywords: anesthetic techniques; anesthetics local; arthroplasty; local anesthetics; regional; ropivacaine; toxicity.

Grants and funding

The authors acknowledge support from the European Union’s Horizon 2020 research and innovation program under grant agreement No. 857287 (Baltic Biomaterials Centre of Excellence).