Safety of blood reinfusion drains after local infiltration analgesia in total joint replacement.

BACKGROUND: Local infiltration analgesia (LIA) is frequently administered to patient undergoing joint replacement surgical procedures. The aim of the present research was to verify the safety of collected shed blood to be reinfused postoperatively, by measuring levobupivacaine levels in drainage blood in patients undergoing LIA during knee replacement surgery. PATIENTS AND METHODS: 24 patients who underwent total knee arthroplasty (TKA) and 12 scheduled for total hip arthroplasty (THA) who received intraoperative LIA were considered. Blood samples were collected from shed blood which was present in drainage 2 and 5 hours after surgery and serum was analysed by liquid chromatography-tandem mass spectrometry. RESULTS: At 2 hours postoperatively, the median levobupivacaine serum concentration in the collected shed blood was 1.2 mg/L (SD: 4.2) for TKA and 17.13 mg/L (SD: 24.4) for THA. At 5 hours, levobupivacaine concentration was 1.84 mg/L (SD: 2.2) for TKA and 17.5 mg/L (SD: 25.2) for THA. Higher values of average serum levobupivacaine concentration were reported in drains collected from patients who had undergone THA compared to TKA (p<0.001). BMI significantly influenced levels of serum drug, that resulted to be higher in patients with BMI<25 (p= 0.01). CONCLUSION: Levobupivacaine from collected shed blood that would have been returned to the patient, was below toxicity level at 2 and 5 hours after LIA during total joint replacement. The average serum levobupivacaine concentration was found to be higher in drains taken from THA patients than TKA patients. Patients with lower BMI demonstrated the highest levels of levobupivacaine in shed blood and a lower blood volume needed for central nervous system toxicity. Therefore, in patients with a lower BMI undergoing THA, anaesthetic dosage should be reduced or autotransfusion should be avoided to prevent potential risks of toxicity.

Acute normovolemic hemodilution.

Acute normovolemic hemodilution (AHN) is a well known but poorly used "blood saving" method. The authors, based on their own experience and on the "low hematocrit" physiology, present some concepts on AHN and a clinical experience to demonstrate the usefulness and affordability of this method. Consequently we offer several tools concerning both the realization of AHN and the safe use of such dilution, suggesting simple and exciting methods to determine if, when and how to apply this blood saving system.