Ultrasound Plus Nerve Stimulator Versus Nerve Stimulator Guided Lumbar Plexus Block
Condition: Knee Arthroscopy Surgery
Study type: Interventional

Summary: 
      Ultrasound imaging, an effective tool to localize peripheral nerves, may facilitate block
      performance. It allows direct visualization of nerve structures, needle guidance in real-time
      to the target, and observation of local anesthetic diffusion. Some case series have
      demonstrated significantly faster onset time for interscalene blocks, supraclavicular blocks
      and axillary brachial plexus blocks under ultrasound than with conventional techniques.
      Ultrasound guidance also enhances the quality of popliteal sciatic nerve block at the
      popliteal fossa compared with single injection, nerve stimulator-guided block using either a
      tibial or peroneal endpoint. Despite this impressive profile, the application of the
      ultrasound for lumbar plexus blocks has not been studied extensively. It is likely that
      lumbar plexus block (LPB) combined with either a sciatic nerve block or sedation or both is
      equivalent to general anesthesia and neuraxial anesthesia for knee arthroscopy. The lumbar
      plexus block is traditionally performed using surface anatomical landmarks and nerve
      stimulation. Ultrasound imaging of the anatomy relevant for LPB is challenging because of its
      deep anatomic location and the "acoustic shadow" of the overlying transverse processes.
      Recently, Karmakar M.K. etc. has demonstrated that a paramedian transverse scan (PMTS) of the
      lumbar paravertebral region with the ultrasound beam being insonated through the
      intertransverse space (ITS) and directed medially toward the intervertebral foramen
      (PMTS-ITS) may overcome the problem of the "acoustic shadow" and allow clear visualization of
      the anatomy relevant for LPB. However, the application of a PMTS-ITS used for lumbar plexus
      blocks has not been studied extensively and its advantages are not validated in a clinical
      study. Thus, we designed this prospective, randomized, subject and assessor blinded,
      parallel-group, active-controlled study to compare a PMTS ultrasound-guided lumbar plexus
      block combined with nerve stimulation and a conventional technique on time required to
      readiness for surgery in patients undergo knee arthroscopy surgery.
    


Intervention name(s): Ultrasound and nerve stimulator guided lumbar plexus block; Nerve stimulator guided lumbar plexus block
Intervention type(s): Procedure; Procedure
Intervention description(s): An insulated nerve block needle connected to a nerve stimulator that was delivering a current of 1.5 mA at a frequency of 2 Hz was then inserted in the long axis (in- plane) of the ultrasound transducer towards the the hypoechoic psoas compartment. If the quadriceps contraction which produces patella twitching was elicited with an initial current of 1.5mA,then the current should be reduced until contraction is still present between 0.3 to 0.5 mA .Afterward, the lumbar plexus nerve block was performed by using 30mL of 0.5% ropivacaine. Contraction should stop below a current of 0.3mA, otherwise intraneural needle position should be suspected.; The block was conducted following traditional Winnie approach. The accepted end point for the lumbar plexus is stimulation of the femoral nerve component, observed by contraction of the quadriceps muscle. Quadriceps contraction which produces patella twitching should be sought with an initial current of 1.5mA, and once elicited the current should be reduced until contraction is still present between 0.3 to 0.5 mA. Afterward, the lumbar plexus nerve block was performed by using 30mL of 0.5% ropivacaine. Contraction should stop below a current of 0.3mA, otherwise intraneural needle position should be suspected.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Care Provider, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Lumbar plexus block; Ultrasound guidance; Nerve stimulator