Puncture

The needle is introduced at the point of puncture perpendicular to the skin into strictly antero-posterior a para-median plan. The intensity of stimulation is regulated between 2 and 4 mA for one duration of 0.1 ms stimulation. The needle progresses slowly through the mus-cular masses until the contact of the apophysis costiforme or until the required stimulation of the femoral nerve on the level of the lumbar plexus (rise of the knee cap). We believe that a response to 0.6 or 0.8 mA is sufficient. Careful aspiration is performed to ensure the absence of blood or CSF.

For a single injection a volume of 30 ml of
anesthetic solution is necessary. The injection
must slow and in gradual. This volume assures
adequate spread of local anesthetic (Figures
on right correspond to the psoatic opacifica-
tion of space). The form in spindle corres-
ponds to the drawing of the muscle psoas
with the pool showing the space between the
muscle psoas and the quadratus lumbarum. It
is important to rule out the epidural spread,
as well intra-peritoneal, epidural or too cepha-
lad placement of the catheter.

When a continuous catheter is placed, the tip should be inserted 5 cm beyond the needle opening.