In this prospective randomized pilot study on APG in total knee arthroplasty, differences in favour of the use of platelet gel were found, but these were subjective evaluations, marginal in effect, or did not reach statistical significance. The use of drains might have decreased the concentration of delivered platelets and may have diminished the effect. However, in this study, a statistically significant clinically important effect in favour of platelet gel application was not found. Further studies with larger numbers of patients, and without the use of drains, are warranted to investigate the possible benefits of autologous platelet gel in total knee arthroplasty.

AIMSNo pharmacokinetic data exist on doses of ropivacaine larger than 300 mg for peripheral nerve block in man, although in clinical practice higher doses are frequently used. The purpose of the present study was to describe the pharmacokinetic profile in serum of 450 mg ropivacaine with and without epinephrine in patients undergoing anterior cruciate ligament reconstruction. METHODSTwelve patients were randomly allocated to receive a single shot combined sciatic/femoral nerve block with 60 ml of either ropivacaine 0.75% alone (group R, n = 6) or ropivacaine 0.75% plus epinephrine 5 mg ml -1 (group RE, n = 6). Venous blood samples for total and free ropivacaine serum concentrations were obtained during 48 h following block placement. Pharmacokinetic parameters were calculated using a non-compartmental approach. RESULTSResults are given as mean (SD) for group R vs. group RE (95% CI of the difference). Total Cmax was 2.81 (0.94) mg ml -1 vs. 2.16 (0.21) mg ml -1 (95% CI -0.23, 1.53). tmax was 1.17 (0.30) h vs. 1.67 (0.94) h (95% CI -1.40, 0.40). The highest free ropivacaine concentration per patient was 0.16 (0.08) mg ml -1 vs. 0.12 (0.04) mg ml -1 (95% CI -0.04, 0.12). t1/2 was 6.82 (2.26) h vs. 5.48 (1.69) h (95% CI -1.23, 3.91). AUC was 28.35 (5.92) mg ml -1 h vs. 29.12 (7.34) mg ml -1 h (95% CI -9.35, 7.81). CONCLUSIONSFree serum concentrations of ropivacaine with and without epinephrine remained well below the assumed threshold of 0.56 mg ml -1 for systemic toxicity. Changes in pharmacokinetics with epinephrine co-administration did not reach statistical significance. WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• For peripheral nerve blocks, larger doses of local anaesthetic than recommended are frequently used. In the absence of pharmacokinetic data, using higher than recommended doses may pose a medico-legal problem in cases of local anaesthetic systemic toxicity. WHAT THIS STUDY ADDS• This is the only study describing the pharmacokinetic profile in serum of 450 mg ropivacaine with and without epinephrine for combined sciatic/femoral nerve block. Free serum concentrations of ropivacaine in both groups remained well below the assumed threshold of 0.56 mg ml -1 for systemic toxicity.

P Pu ur rp po os se e: : To report successful resuscitation of ventricular fibrillation induced by accidental intravascular injection of ropivacaine.C Cl li in ni ic ca al l f fe ea at tu ur re es s: : A 15-yr-old healthy girl weighing 59 kg was scheduled for transposition of the tibial tuberosity under combined sciatic/three-in-one block. No premedication was given. In the induction room, an iv infusion was started, along with electrocardiogram monitoring, non-invasive blood-pressure measurement and pulse-oximetry. The sciatic nerve was found with the use of a nerve stimulator at the first attempt by the classical approach of Labat. Aspiration for blood was negative and the injection of ropivacaine 0.75% without epinephrine started. Convulsions, followed within seconds by ventricular fibrillation occurred at the end of the injection of 18 mL ropivacaine 0.75%. Oxygen was administered by face mask ventilation and immediate defibrillation was successful on the second attempt (2 × 200 joules). Within two minutes convulsions stopped and normal cardiac rhythm returned. Propofol and sufentanil were injected and a laryngeal mask inserted to start general anesthesia for surgery. Postoperatively no evidence of sciatic block could be demonstrated. The patient did not remember the event and was discharged the following day with no residual effects.

Both approaches are comparable regarding clinical efficacy for anesthesia of the shoulder and upper arm.

The practical advantages of the stimulating catheter, as reported by previous investigators, were not obvious in this clinical situation. In terms of outcome measures such as pain scores and morphine consumption, we found no significant differences between stimulating and non-stimulating catheters.