[Music] the pectoralis or pex blocks are a set of fascial plane blocks used for anesthetizing nerves of the chest wall and in this video we'll discuss the anatomy approach and some tips for success for pecs one and two there are two pex blocks and they each serve a different purpose although they're often done together the first aims to put local anesthetic in the plane between the pec major and minor muscles thereby blocking the medial and lateral pectoral nerves these nerves supply the pec muscles themselves but no overlying skin this has been termed the pecs one block if we place local anesthetic one plane deeper so between pec minor and serratus anterior muscles this results in an expanse of local anesthetic spreading along the side of the chest wall anesthetizing the lateral cutaneous branches of roughly t2 to t6 this is commonly known as pex 2. while the original description of the pex 2 incorporated the pex one block most anesthesiologists describe them separately referring to the first block as pecs one and the second as pex two here we see contrast spreading in two distinct fascial planes the pex1 injection is sandwiched between two pec muscles and the much more expansive spread of injectate is the result of the pex2 injection you can appreciate how local anesthetic in this location would surely anesthetize lateral cutaneous branches as they emerge from between the origins of the serratus muscle on the lateral ribs pex 1 is an excellent block for anything involving the pec muscles themselves we use them routinely for breast reconstruction with sub-muscular implants or tissue expanders as it relieves that dull achy sensation associated with stretching of the pec we'll also include the pecs one if the surgical oncologist is performing a modified radical mastectomy where the pec major fascia is being stripped off the muscle we've also had great success using this for thoracoscopic surgery and minimally invasive heart surgery pecs 2 achieves a sensory block of the skin breast and soft tissue corresponding to the t2t6 nerve roots this is conveniently well suited to breast surgery and this is our major indication for pex2 blocks we also use it for chest wall procedures and because it reliably gets both t2 and t3 the axilla is well covered it's therefore very useful for axillary dissection or sentinel node biopsy the intercostal brachial nerve a branch of t2 is also consistently blocked and we commonly add this block to a brachial plexus block for additional skin coverage during av fistula creation note that the midline of the chest is spared because we don't get the anterior cutaneous branches with this technique that's easily fixed with some additional local infiltration in that area for positioning the arm should be abducted 90 degrees to stretch the pec muscles out and to allow for probe movement over to the lateral chest wall the probe is placed on the chest wall just medial to the coracoid process in a parasagital orientation we typically stand at the head of the bed so the needle can be easily guided in plane toward the target with a probe in this orientation you'll see the typical sono anatomy associated with infraclavicular brachial plexus block including the pec major and minor muscles and the axillary artery there is a sequence of important probe maneuvers that set you up to see the correct anatomy and increase block success the first is to tilt medially and then twist so the transducer is in line with a delta pectoral groove this has the effect of bringing the chest wall into view underneath the axillary vessels counting the ribs is crucial and we want to know which rib is which the rib directly underneath the axillary vein is a second rib from here the probe is translated inferiorly and laterally until the next rib is encountered this is the third rib you can appreciate the fascial plane between the two pec muscles here this is the target for the pex one block the probe is then translated in the same inferior and lateral direction until the fourth rib is visualized usually at this point we can see a new slip of muscle that appears overlying the rib underneath the pec minor this is serratus anterior and the plane between these two muscles pec minor and serratus is the target for the pex two block okay let's look at this in real time here's the pec major and minor and the third rib you can see pleura on either side of the rib the needle enters from the cephalat aspect passing through the pec major and entering the fascial plane between the two pec muscles after negative aspiration 10 mils of local anesthetic is administered there's often a visible artery in this plane above the third rib this is the pectoral branch of the thoracoacromial artery it's a good landmark as it's close to the medial and lateral pectoral nerves but take care not to injure it moving down a few centimeters we now see the fourth rib the two pec muscles and the serratus anterior muscle the needle passes through both pec muscles and then finds the fascial plane you can see the two layers unzippering here nicely this requires slightly more volume and we find that 20 mils does the job nicely the choice of local anesthetic depends on the indication and the desired duration of action but in general these are small nerves and don't require a high concentration of local anesthetic to get a good effect here are some tips for pec success number one if you decide to perform both blocks do the pex 2 first it's deeper so you don't obscure your visualization with your first injection also as a needle is being withdrawn it tends to fall right into the correct pex one plane over the third rib where you can put your final 10 ml of local anesthetic it's very common for beginners to lose sight of the ribs they become fuzzy and indistinct this is almost always because the beam is directed too laterally and you're missing the chest wall the solution is to tilt or translate more immediately like we see here the recommended volumes are easy to remember 10 mils for one 20 for two and finally if the patient's quite big or has a lot of soft tissue to deal with it's often easier and perhaps safer to come out of plane rather than lose your needle trying to go in plane using the fourth rib as a backstop for the pex2 block the needle can be carefully advanced to contact the bone and then 20 mils of local anesthetic administered deep to the serratus muscle comparative studies suggest that the block dynamics are roughly the same whether the locals deposited above or below serratus pex blocks are safe easy to do and in some studies appear to be equivalent to pair vertebral blocks for post-operative analgesia following mastectomy we've had good success with them for breast procedures as well as a variety of other axilla and chest wall procedures and they are firmly part of our regional anesthesia toolkit