There is NO Doubt!
This fascia iliaca video shows several key ultrasound cues that should always lead you to a successful nerve block. After the needle is advanced in a cranial direction, the initial injection reveals a very thin distribution of local anesthetic which does not inject easily (noted by assistant). Further, upon this injection, the fascia iliaca becomes more evident just beneath the local anesthetic spread. This local was initially given within the connective tissue surrounding the sartorius muscle. A second video that I will post soon will demonstrate a transverse view after the injection that demonstrates local anesthetic in this location as well as in the appropriate position.
As the needle is advanced slightly, a brief ‘tenting’ downward of the fascia iliaca is seen and felt as well. Once the second injection begins, there is a clear difference in the way the local spreads. Under very little pressure, the local spreads quickly in a cranial direction and widely spreads the space between the iliopsoas muscle and the fascia iliaca. Notice that there are no ‘blotchy muscular striations’ within and around the final injection which would indicate that it is actually within the body of the muscle.
If you do not see the clear cranial spread into the pelvis, as we note with the initial injection, you are probably within the sartorius muscle and just above your target. Since the sartorius muscle attaches to the ASIS just above this location, the spread will not move that direction very easily at all. I have mentioned before that it is ok -and sometimes necessary to go through the sartorius muscle when the patient has a very narrow ‘Triangle’ (see other post on this subject). It is just important to scan medially and laterally to confirm the appearance and thickening of the sartorius muscle as you move laterally to confirm that it is exactly what you thought it was!