Date Published: August 5, 2012
Publisher: Hindawi Publishing Corporation
Author(s): Torben Breindahl, Ole Simonsen, Peter Hindersson, Bjarne Brødsgaard Dencker, Mogens Brouw Jørgensen, Sten Rasmussen.
Aims. To study the safety of autotransfusion following local infiltration analgesia (LIA) with ropivacaine. Background. Knowledge of blood concentrations of ropivacaine after LIA and autotransfusion is crucial. However, very limited data are available for toxicological risk assessment. Methods. Autotransfusion was studied in patients after total knee arthroplasty (TKA: n = 25) and total hip arthroplasty (THA: n = 27) with LIA using 200 mg ropivacaine, supplemented with two postoperative bolus injections (150 mg ropivacaine). Drainage blood was reinfused within 6 h postoperatively. Results. Reinfusion caused a significant increase in the serum concentration of total ropivacaine for TKA from 0.54 ± 0.17 (mean ± SD) to 0.79 ± 0.20 μg/mL (P < 0.001) and a nonsignificant increase for THA from 0.62 ± 0.17 to 0.63 ± 0.18 μg/mL. The maximum free (unbound) concentration after reinfusion was 0.038 μg/mL. Peak total and free venous ropivacaine concentrations after 8 h and 16 h postoperative bolus injections were 2.6 μg/mL and 0.11 μg/mL, respectively. All concentrations observed were below the threshold for toxicity and no side effects were observed. Conclusion. Autotransfusion of patients undergoing knee or hip arthroplasty after local infiltration analgesia with 200 mg ropivacaine can be performed safely, even supplemented with 8 h and 16 h postoperative bolus injections.
Total knee and hip arthroplasty (TKA, THA) for osteoarthritis is still performed on broader indications even in elderly patients and in patients with previous or current medical conditions. In particular, comorbidity-like cardiovascular diseases and conditions with increased risk of bleeding or previous thromboembolic events are major challenges.
Drainage blood volume after THA was significantly lower than after TKA (P = 0.007) (Table 1). Total serum concentration of ropivacaine before autotransfusion was 0.54 ± 0.17 μg/mL after TKA and 0.62 ± 0.17 μg/mL after THA. Autotransfusion caused a significant increase in total ropivacaine concentration to 0.79 ± 0.20 μg/mL for TKA (P < 0.001) and a non-significant increase to 0.63 ± 0.18 μg/mL for THA. Maximum amount of reinfused ropivacaine was 7.2 mg. The total serum concentration of ropivacaine measured at the end of autotransfusion did not exceed 1 μg/mL (Table 1). The peak free concentration observed for all patients was 0.038 μg/mL. No signs of toxicity were observed for any patient during the study. We conclude that autotransfusion of patients undergoing knee or hip arthroplasty after local infiltration analgesia with 200 mg ropivacaine can be performed safely, even supplemented with 8 h and 16 h postoperative bolus injections. All concentrations observed were below the estimated threshold for systemic toxicity and no side effects were observed after autotransfusion. However, infiltration techniques imply usage of large amounts of local anaesthetics and there is a lack of knowledge concerning safe reinjection protocols. Future studies concerning dose and timing for optimal bolus injections are relevant, as well as simulations, mathematical modelling, and population pharmacokinetic analyses. Source: http://doi.org/10.1155/2012/458795