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

Abstract

Study objectiveDescribe 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). DesignA single center retrospective cohort study between May 2018 and November 2022. SettingA major academic hospital. PatientsPatients who had both a PAI and PNB while undergoing primary, revision, total, partial, unilateral, or bilateral knee arthroplasty. InterventionsNone. MeasurementsCalculate 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 resultsThere 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. ConclusionsOver 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.