[Music] the transversus abdominis plane block is a useful technique to provide analgesia for procedures on the lower abdomen in this video we'll describe the anatomy sono anatomy and some tips and tricks to ensure your patients get the most out of your tap blocks the abdominal wall is made up of several muscles posteriorly we have the psoas major the erector spinae group the quadratus lumborum and latissimus dorsi running down the anterior midline is the rectus abdominis muscle the lateral wall of the abdomen consists of three stacked muscles and fascia layers the innermost is the transversus abdominis the middle and the thickest layer is the internal oblique and the outermost is the external oblique muscle the spinal intercostal nerves exit the vertebral foramina and wind their way around the trunk between the transversus abdominis and the internal oblique they penetrate the rectus sheath before emerging anteriorly to innervate the anterior midline at the mid-axillary line they also give off a lateral cutaneous branch which divides to innervate the anterolateral and posterolateral aspects of the trunk together the anterior cutaneous and lateral cutaneous branches innervate the majority of the truncal surface minus the area at the posterior midline the intermuscular fascial plane the nerves travel in within the abdomen is called the transversus abdominis plane we're going to block the nerves here upstream of the lateral branch takeoff so we get the maximum effect here we see the superficial muscles of the abdomen on the left the external oblique and its aponeurosis cover the entire lateral abdominal wall on the right we've peeled away the external and internal obliques and we can see the transversus abdominus and rectus abdominus muscles we've done this with a purpose so we can see both the lateral and anterior cutaneous branches of the relevant nerves and where they travel first we have the lateral and anterior cutaneous branches of t10 you can see that the lateral branch divides and sends a twig posteriorly while the anterior branch two layers deeper keeps on trucking until it pops out through the rectus t11 is very much the same story the t12 or subcostal nerve sends a lateral continuous branch down over the iliac crest and innervates the skin over the gluteus medius the anterior branch also ends up terminating superficial terractus the iliohypogastric nerve has a twig to the gluteal region before continuing on towards the suprapubic area and finally the ilioinguinal nerve runs alongside the inguinal ligament these last two nerves are primarily derived from l1 of course there are other nerves in the upper abdomen but these aren't relevant to our tap block discussion and they'll be covered in a different video the aim of the block is to deposit local anesthetic here in the transverse's abdominis plane if we stay at or posterior to the midaxillary line we'll be sure to catch the takeoff of those lateral cutaneous branches and ensure we'll cover both the midline and the lateral aspects of the lower abdomen with the patient's supine the probe is applied to the mid-axillary line between the iliac crest and the costal margin a blocked needle is inserted in plane from the anterior aspect and advance to the target fascial plane here's a typical sonogram for the tap block note the three layers of muscle with subcutaneous fat above and the abdominal cavity below the top plane is the bright fascial line between the internal oblique and transversus abdominis muscle this is where the nerves travel a needle will be seen entering the screen from the anterior aspect a good way to make sure you're looking at the correct muscles is to start scanning near the abdominal midline here we see the thick internal oblique inserting into the linea semilunaris as we travel more laterally the external oblique and transversus abdominis muscle appear superficially and deep respectively we continue to follow these three muscles around to the mid axillary line where the transversus comes to an end this is an important landmark for the tap lock you want to ensure that your local anesthetic reaches this point to provide the best possible spread and therefore sensory block to the nerves here we see the needle approaching from the anterior aspect located within the internal oblique muscle the needle tip enters the top plane and a small test injection of saline confirms we're in the right location we then switch to the local anesthetic and continue to inject the needle is continually advanced within the dissected plane in order to leverage hydraulic force to unzipper the two muscles as a needle is advanced we move the probe in the same posterior direction to keep the tip on the screen and here we see that we've reached the end of the transverse's abdominus which is our goal for injection once the injection is finished the needle is removed and the block is repeated on the contralateral side this is a volume block and we seem to get our best results when we use 25 to 30 mils on each side make sure you're careful with your concentrations when using large volumes of local anesthetic these are small nerves and dilute solutions work well to get a good effect we can expect to get the lower part of the abdomen from about the umbilicus to the pubis and including the skin on the lateral aspect of the pelvis and hip joint we use a tap block for cesarean delivery lower abdominal pelvic incisions such as for hysterectomy bladder surgery and some oncologic procedures we also use it for anterior approaches to lumbar spine surgery what tap is less ideal for is anything above the umbilicus it really isn't designed for that and we have other blocks such as the subcostal tap the ql and the esp block and here are some tap tips number one use the tectonic sign to define the layers in a slim patient it's often not hard to identify the three muscle layers in the screen in many patients however instead of three layers the screen looks like a seven layer bean dip now remember that the internal and external oblique muscles are oriented at 90 degrees to each other and because of that if you fan your probe in a cephalocodot fashion the muscle layers will appear to run back and forth with respect to each other like tectonic plates sliding during an earthquake the transversus muscle and the fat don't tend to give the illusion of motion and so you can quickly identify the obliques and work from there number two you want to hit the top plane at a very shallow angle because you need to move that needle along if you have to turn a 60 degree corner after hitting the plane it's not going to be a satisfying block calculate your depth to the tap plane on the screen and then insert your needle that far out from your probe surface to hedge for safety you can always start by aiming laterally at your probe surface and once you see your needle on the screen walk it down sequentially until you're in the correct plane and lastly i'll say it again you need to stick and move stick and move in the early days of tap we got a lot of results like this danish volunteer study and it was because we were landing the needle in one spot injecting and then high-fiving each other and walking away and because all the locals stayed in one location we got less than ideal results the tap plane often doesn't peel apart like a buttery rectus sheath block you need to use the hydraulic pressure head of your solution to unzipper that plane and ensure that you have the greatest degree of spread possible when we pay attention to this technical aspect of the block our results are consistent and reliable