Spinal mepivacaine with fentanyl for outpatient knee arthroscopy surgery: a randomized controlled trial.

BACKGROUND: The foremost limitation of local anesthetic solutions for spinal anesthesia in the outpatient setting is prolonged motor blockade and delayed ambulation. The purpose of this study was to determine if the addition of intrathecal fentanyl to low-dose spinal mepivacaine provides adequate anesthesia with shorter duration of functional motor blockade for ambulatory knee surgery compared with spinal mepivacaine alone. METHODS: Following institutional review board approval and informed consent, 34 patients undergoing unilateral knee arthroscopy were enrolled in this study. The patients were randomly assigned to receive either 30 mg of isobaric mepivacaine 1.5% plus fentanyl 10 microg (M + F group) or 45 mg of isobaric mepivacaine 1.5% alone (M group) intrathecally. Postoperatively, the times to achieve sensory block regression to the S1 dermatome and to attain functional motor block recovery enabling ambulation were recorded. All assessments were blinded. RESULTS: The time to completion of Phase I recovery was shorter in the M + F group (104.6 +/- 28.4 min) than in the M group (129.1 +/- 30.4 min; P = 0.023). Regression of sensory blockade to S1 was earlier in the M + F group (118.4 +/- 53.5 min) than in the M group (169.7 +/- 38.9 min; P = 0.003). Patients in the M + F group (176.4 +/- 40.3 min) were able to ambulate significantly earlier than those in the M group (205.6 +/- 31.4 min; P = 0.025). No cases of transient or persistent neurological dysfunction were noted. CONCLUSIONS: When compared with 45 mg isobaric mepivacaine 1.5%, an intrathecal dose of 30 mg isobaric mepivacaine 1.5% plus 10 microg fentanyl produces reliable anesthesia, hastens block regression, shortens stay in Phase I recovery, and enables earlier ambulation for patients undergoing unilateral knee arthroscopy (Registration no. NCT00803725).

Feasibility and efficacy of ultrasound-guided block of the saphenous nerve in the adductor canal.

BACKGROUND AND OBJECTIVES: Saphenous nerve (SN) block can be technically challenging because it is a small and exclusively sensory nerve. Traditional techniques using surface landmarks and nerve stimulation are limited by inconsistent success rates. This descriptive prospective study assesses the feasibility of performing an ultrasound-guided SN block in the distal thigh. METHODS: After the research ethics board's approval and written informed consent, 20 patients undergoing ankle or foot surgery underwent ultrasonography of the medial aspect of the thigh to identify the SN in the adductor canal, as it lies adjacent to the femoral artery (FA), deep to the sartorius muscle. An insulated needle was advanced in plane under real-time guidance toward the nerve. After attempting to elicit paresthesia with nerve stimulation, 2% lidocaine with 1:200,000 epinephrine (5 mL) and 0.5% bupivacaine (5 mL) were injected around the SN. RESULTS: The SN was identified in all patients, most frequently in an anteromedial position relative to the FA, at a depth of 2.7 +/- 0.6 cm and 12.7 +/- 2.2 cm proximal to the knee joint. Complete anesthesia in the SN distribution developed in all patients by 25 mins after injection. CONCLUSIONS: In this small descriptive study, ultrasound-guided SN block in the adductor canal was technically simple and reliable, providing consistent nerve identification and block success.

Implications of a permanent cardiac pacemaker in peripheral nerve blockade.

Patients with permanent cardiac pacemakers (PPMs) are vulnerable to electromagnetic interference from electrical equipment used in the operating room environment. Electromagnetic interference may lead to PPM malfunction with potential harmful effects to the patient. Conventional techniques for peripheral nerve blockade include the use of electrical nerve stimulation (NS) for nerve localization. The hazards of NS, especially when applied near the implanted PPM sites, are not known. In the absence of available guidelines regarding the safe use of NS in the setting of an implanted PPM, we recommend a combined guidance approach for peripheral nerve blockade using ultrasound for nerve localization along with low-current NS for nerve identification.

The role of a preprocedure systematic sonographic survey in ultrasound-guided regional anesthesia.

BACKGROUND AND OBJECTIVES: The presence of neurovascular abnormalities may increase the risk of complications following regional anesthesia techniques. Use of conventional nerve localization methods may fail to detect such abnormalities and potentially result in block failure and/or unintentional neurovascular injury. METHODS: We use 2 examples to illustrate this, and the concept that systematic use of a preprocedure ultrasound (US) scan may serve as an aid both for diagnosis of abnormal anatomy, and in planning the appropriate anesthetic technique. RESULTS: Use of a preprocedure US scan helped to diagnose abnormal anatomy and assisted in planning a more appropriate anesthetic technique. CONCLUSIONS: We believe that a systematic sonographic survey prior to regional anesthesia can be a valuable bedside screening tool to assess the suitability and challenges involved in performing US-guided peripheral nerve block.