Safety and Pharmacokinetics of Levobupivacaine Following Fascia Iliaca Compartment Block in Elderly Patients.

BACKGROUND: Fascia iliaca compartment block (FICB) is an increasingly popular analgesic technique in elderly patients with hip fracture. Despite requiring large volumes of local anaesthetic, there are no plasma pharmacokinetic data on FICB in elderly patients. OBJECTIVES: The objective of this study was to determine the pharmacokinetic profile of a levobupivacaine 75 mg (30 mL 0.25%) FICB dose in patients aged ≥ 80 years with fractured femur. METHODS: This was a single-arm descriptive pilot study. Twelve adults aged ≥ 80 years with hip fracture received FICB performed under ultrasound guidance. Venous blood was sampled at 10, 20, 30, 45, 60, 75, 90, 105, 120 and 240 min after injection. Total plasma levobupivacaine concentration was measured by mass spectrometry. The main outcome measures were pharmacokinetic parameters, including maximum observed plasma concentration (Cmax), time to reach Cmax (tmax) and area under the plasma concentration-time curve. RESULTS: The median (interquartile range [IQR]) Cmax was 0.82 µg/mL (0.47-1.03). tmax was 45 min (41:20-60:00). No evidence of toxicity was identified. Plasma levobupivacaine concentrations were below the threshold associated with toxicity in younger, healthy patients (2.6 µg/mL). No association was found between individual patient Cmax and α1-acid glycoprotein, weight or body mass index, although the study was not powered for these outcomes. CONCLUSIONS: Absorption of levobupivacaine was slow and all patients had plasma concentrations below the toxic threshold. This pharmacokinetic analysis concludes that the technique appears to be well-tolerated and efficacious at reducing pain and is associated with systemic plasma concentrations unlikely to be associated with major adverse effects in elderly patients. CLINICAL TRIAL REGISTRATION: ISRCTN27364035 (UK Clinical Trials Gateway).

Is circumferential injection advantageous for ultrasound-guided popliteal sciatic nerve block?: A proof-of-concept study.

BACKGROUND: Ultrasound (US) guidance, in some instances, can increase the success rate and reduce the onset and procedure times for peripheral nerve blockade compared with traditional nerve localization techniques. The presumptive mechanism for these benefits is the ability to accurately inject local anesthetic circumferentially around the target nerve. We aimed to determine whether ensuring circumferential spread of local anesthetic is advantageous for US-guided popliteal sciatic nerve block. METHODS: Sixty-four adult patients undergoing US-guided popliteal sciatic block for elective foot and ankle surgery were randomly assigned to 1 of 2 groups, circumferential or single-location injection. Using a short-axis nerve view and out-of-plane needle approach, the needle tip was advanced to the posterior external surface of the sciatic nerve. A 30-mL local anesthetic admixture (1:1 lidocaine 2%/bupivacaine 0.5% with 1:200,000 epinephrine) was injected either entirely at this location (single location) or incrementally at multiple locations to ensure circumferential spread around the sciatic nerve (circumferential). Sensory and motor functions were assessed by a blinded observer at predetermined intervals. The primary outcome was sensory block defined as loss of sensation to pinprick in the distribution of both tibial and common peroneal nerves at 30 mins after injection. RESULTS: Sensory block was achieved in 94% of patients in the circumferential injection group compared with 69% in the single-location injection group (P = 0.010). There were no differences detected in block performance time, pain during block performance, or block-related complications between groups. CONCLUSIONS: Ultrasound-guided circumferential injection of local anesthetic around the sciatic nerve at the popliteal fossa can improve the rate of sensory block without an increase in block procedure time or block-related complications compared with a single-location injection technique.

Dexamethasone added to mepivacaine prolongs the duration of analgesia after supraclavicular brachial plexus blockade.

BACKGROUND AND OBJECTIVES: Corticosteroids have been used successfully to prolong the duration of local anesthetic action after peripheral nerve and epidural blockade. We hypothesized that the addition of dexamethasone to mepivacaine would prolong the duration of analgesia after ultrasound-guided supraclavicular brachial plexus block for patients undergoing upper-limb surgery. METHODS: After Federal Health Department and institutional review board approval, 45 adult patients undergoing elective hand or forearm surgery under supraclavicular brachial plexus blockade were randomized to receive either 30 mL mepivacaine 1.5% plus dexamethasone 8 mg (4 mg/mL), or 30 mL mepivacaine 1.5% plus 2 mL normal saline. The primary outcome measure was duration of analgesia. Secondary outcomes included onset times of sensory and motor blockade, pain and satisfaction scores, analgesic consumption, and block-related complications. RESULTS: Patient characteristics were similar between groups. The median duration of analgesia was significantly prolonged in the Dexamethasone group (332 mins; interquartile range, 225-448 mins) compared with the Normal Saline group (228 mins; interquartile range, 207-263 mins; P = 0.008). The onset times of sensory and motor block were similar between the groups. Complications were minor and transient and did not differ between groups at 2 weeks postoperatively. CONCLUSIONS: The addition of dexamethasone to mepivacaine prolongs the duration of analgesia but does not reduce the onset of sensory and motor blockade after ultrasound-guided supraclavicular block compared with mepivacaine alone.