Plain articaine or prilocaine for spinal anaesthesia in day-case knee arthroscopy: a double-blind randomized trial.

BACKGROUND: Both prilocaine and articaine are short-acting local anaesthetics suited for spinal anaesthesia for day-case knee arthroscopy. Articaine is thought to have a faster onset and shorter duration of action than prilocaine, although no comparative study has been published in the anaesthetic literature. METHODS: In this prospective randomized double-blind study, spinal anaesthesia was performed in 72 ASA I-II patients undergoing knee arthroscopy with 50 mg of either plain prilocaine or plain articaine. The primary outcome variable was duration of motor block. Secondary outcomes were onset of sensory and motor blocks, maximum spread of the sensory block, time to spontaneous voiding, and side-effects. RESULTS: Time to full motor function recovery was shorter after articaine than prilocaine [mean (SD) 140 (33) vs 184 (46) min, respectively, P<0.001]. Time to spontaneous voiding was shorter after articaine than prilocaine [mean (SD) 184 (39) vs 227 (45) min, respectively, P<0.001]. One patient in the articaine group reported mild transient neurological symptoms (TNS) limited to the first postoperative day, but there were no significant differences in adverse effects between the groups. CONCLUSIONS: Spinal anaesthesia with plain articaine 50 mg resulted in a faster recovery of motor function and earlier spontaneous voiding compared with plain prilocaine 50 mg. Surgical anaesthesia was not different. The incidence of TNS was low.

The pharmacokinetics of ropivacaine after four different techniques of brachial plexus blockade.

Arterial plasma concentrations of ropivacaine were measured after brachial plexus blockade using four different approaches: lateral interscalene (Winnie), posterior interscalene (Pippa), axillary and vertical infraclavicular. Four groups of 10 patients were given a single 3.75 mg.kg(-1) injection of ropivacaine 7.5 mgxml(-1). The pharmacokinetics of ropivacaine were evaluated for 1 h after local anaesthetic injection. The supraclavicular techniques (lateral and posterior) were associated with earlier and higher peak plasma concentrations of local anaesthetic than the infraclavicular techniques (axillary and vertical infraclavicular): mean (SD) values = 3.30 (0.65) microgxml(-1) vs 2.55 (0.62) microgxml(-1) (p = 0.001) in 13.4 (6.9) min vs 25.0 (10.8) min (p = 0.0002). More ropivacaine is taken up by the systemic circulation in the first hour after the supraclavicular approaches; the mean (SD) area under the concentration-time curve was larger: 2.63 (0.51) microgxml(-1).h vs 2.10 (0.49) microgxml(-1).h (p = 0.002). These results show that the technique used for brachial plexus blockade significantly influences the systemic uptake of ropivacaine.

Ultrasound-guided training in the performance of brachial plexus block by the posterior approach: an observational study.

The application of ultrasonography in guiding and controlling the path of the stimulating needle to the brachial plexus via the posterior approach (Pippa technique) was studied. In 21 ASA physical status 1 and 2 patients, scheduled for surgery of the shoulder or upper arm, needle insertion was monitored by ultrasonography and the interaction between needle, surrounding structures and brachial plexus was followed. During injection, the spread of local anaesthetic was visualised and a prediction of block success was made. One failure was predicted. Complete block was achieved in 20 (95%) patients. One potential complication, puncture of the carotid artery, was prevented using ultrasound. Ultrasound is a useful tool in the training and performance of a neurostimulation-guided brachial plexus block by the posterior approach. Ultrasonographic guidance may prevent serious complications associated with this approach to the brachial plexus.

A comparison of the vertical infraclavicular and axillary approaches for brachial plexus anaesthesia.

BACKGROUND: This prospective, randomized study compared the efficacy of the vertical infraclavicular and axillary approaches using a single injection blockade of the brachial plexus. The primary endpoint was complete blockade in dermatomes C5-Th1, while secondary endpoints included onset time, motor block, block performance time, surgical success rate, patient satisfaction, and side-effects/complications. METHODS: Sixty patients, American Society of Anesthesiologists physical status I or II, scheduled for surgery of the forearm or hand received either a vertical infraclavicular (n = 30) or an axillary block (n = 30). A single injection of 0.5 ml/kg ropivacaine 7.5 mg/ml was made after electrolocalization of nerve fibres corresponding to the median nerve at maximum 0.5 mA (2 Hz, 0.1 ms). Onset and distribution of analgesia and motor block were assessed at 5, 10, 15, 20, 30 and 60 min after the local anaesthetic injection. A complete block was defined as analgesia in all dermatomes (C5-Th1) at 60 min post-injection. RESULTS: The vertical infraclavicular approach provided complete blockade in 29 patients (97%) and the axillary approach in 23 patients (77%). Analgesia in C5-C6 dermatomes and corresponding motor block occurred significantly more frequently in the vertical infraclavicular approach, which also had the shortest onset time. Block procedure was quicker in the axillary approach. Side-effects were similar in both groups, and there were no permanent sequelae. Patient satisfaction was equally high in both groups. CONCLUSION: The vertical infraclavicular approach provides a more complete block than the axillary approach when using a single injection technique and equal volumes/doses of local anaesthetic.

Steady state bupivacaine plasma concentrations and safety of a femoral "3-in-1" nerve block with bupivacaine in patients over 80 years of age.

OBJECTIVES: Fracture of the upper femur is a common injury in the elderly. Several anesthetic techniques exist for surgery of traumatic hip fracture. The aim of this investigation was to study plasma concentrations and safety of 2 mg/kg bupivacaine in a femoral "3-in-1" nerve block in patients older than 80 years of age. SUBJECTS AND METHODS: A 3-in-1 femoral nerve block, combined with a general anesthetic was used in 10 elderly patients aged over 80 years. They were undergoing emergency surgery for stabilization of their fractured femur. Bupivacaine plasma concentrations of radial artery blood samples were assessed over a 6-hour period after a femoral 3-in-1 injection of 2 mg/kg bupivacaine 0.375% with epinephrine (1:400,000). RESULTS: No toxic reactions to bupivacaine were seen. In 8 of the 10 patients per- and postoperative analgesia were adequate as a result of the nerve block. Patients experienced loss of sensation and analgesia for 26.6 +/- 4.6 hours (mean +/- SD). This was inversely related to the apparent steady state concentration of bupivacaine. The mean of the individual peak plasma concentrations of bupivacaine (C(max) was 0.74+/- 0.64 microg/ml. The highest plasma concentration was 1.83 microg/ml. Large variations in plasma concentrations were detected in these patients. Bupivacaine metabolites were not detected. CONCLUSIONS: A femoral 3-in-1 nerve block, using 2 mg/kg bupivacaine with epinephrine, provides prolonged pain reliefwithout local anesthetic toxicity in elderly patients. It is a satisfactory supplementary analgesic technique for hip and knee surgery in the elderly.