Principles of Ultrasound Techniques
Surgery of the upper and lower extremity presents anesthesiologists with an alternative to general anesthesia (GA), that being regional anesthesia (RA). RA is most often performed for postoperative analgesia, but RA may also be utilized as the primary technique for intraoperative anesthesia under certain circumstances and with certain patients. For years, neuraxial techniques (spinal or epidural) have been used as the sole regional anesthetic of choice for the lower limb. The advent of low molecular weight heparins (i.e., enoxaparin, fondaparinux) and the potential risk for the development of neuraxial hematomas have limited neuraxial technique use and have led to a much higher use of peripheral nerve blocks (PNBs) in everyday practice. Since the mid-2000s, great improvements have been made in equipment used to perform PNB, including stimulating peripheral nerve catheters and the use of ultrasound to guide in the placement of RA and to assist in the identity of nerves and nerve plexus (Marhofer et al. 2007).