Abstract
BACKGROUND: Intraoperative periarticular injection (PAI) with local anesthetic is an important component of multimodal pain control in total joint arthroplasty (TJA). A potential risk of this practice is serum anesthetic toxicity resulting from the autotransfusion of blood collected from a reinfusion drain. The purpose of this study is to evaluate the levels of bupivacaine in blood collected in an autotransfusion system after use of a PAI in TJA. METHODS: In this prospective study, each TJA patient had an identical PAI consisting of 20 cc of liposomal bupivacaine, 30 cc of 0.25% bupivacaine with epinephrine, and 10 cc of normal saline. An autologous reinfusion drain was utilized in all patients. At 2 and 5 hours postoperatively, blood was collected from the autotransfusion canister and sent to the laboratory to quantify bupivacaine levels. The sums of these levels were compared to the lowest reported serum bupivacaine dose associated with toxicity (1.1 mg/kg). RESULTS: Eleven unilateral TJA patients were enrolled (6 total knee arthroplasties, 5 total hip arthroplasties). The average 2-hour serum bupivacaine level was 2.9 μg (range 0.8-5.6) while the average 5-hour serum bupivacaine level was 4.5 μg (range 0.4-10.0). The average sum of the 2-hour and 5-hour serum bupivacaine level was 5.6 μg (range 0.8-13.6). Each of the 11 patient samples were well below their minimum serum bupivacaine dose toxicity. CONCLUSIONS: Use of a reinfusion drain after PAI with liposomal bupivacaine in TJA appears safe, as bupivacaine levels in the autotransfused blood remains well below the reported minimum serum toxic dose. LEVEL OF EVIDENCE: IV.