Ultrasound Plus Nerve Stimulator Versus Nerve Stimulator Guided Lumbar Plexus Block

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.