Charles Hamilton

Current Status of Blood Transfusion and Antifibrinolytic Therapy in Orthopedic Surgeries

1 Department of Anesthesiology, Wexner Medical Center, Ohio State University, Columbus, OH, USA 2 Department of Neurological Surgery, Wexner Medical Center, Ohio State University, Columbus, OH, USA 3 Department of Neuroscience, Ohio State University, Columbus, OH, USA 4 Drexel University College of Medicine, Philadelphia, PA, USA 5 Temple University School of Medicine, Philadelphia, PA, USA 6 College of Medicine, Wexner Medical Center, Ohio State University, Columbus, OH, USA 7 Orthopedic One, Columbus, OH, USA *Correspondence: nicoleta.stoicea@osumc.edu

Ultrasound-guided supine posterior approach for popliteal sciatic nerve block

To the Editor: Blockade of the sciatic nerve in the popliteal fossa is used for anesthesia and analgesia below the knee. Two common techniques used today are the prone posterior and the supine lateral approaches [1, 2]. The posterior approach with prone positioning is time consuming and problematic, especially for patients who are large and/or difficult to sedate. The supine lateral approach requires passage of the needle through the large lateral muscle groups of the leg, which can be painful, though the parallel needle path to the ultrasound transducer is ideal for visualizing the needle. With a lateral approach, however, some anesthesiologists have difficulty keeping the needle in plane, given the separation between the lateral needle insertion point and the transducer position on the back of the leg. This approach is made more challenging in patients with large legs. We believe the ultrasound-guided supine posterior approach is a novel technique for blocking the two divisions of the sciatic nerve in the popliteal fossa. The patient is supine with the leg elevated (Fig. 1). The sciatic nerve is visualized with a high-frequency linear ultrasound transducer oriented on the back of the leg in the transverse plane to the sciatic nerve. The bifurcation of the common peroneal nerve and posterior tibial nerve is identified near the popliteal fossa. Lidocaine 1% is used to anesthetize the skin and subcutaneous tissue. A 50 mm block needle is introduced out-of-plane and guided into the space between the common peroneal and posterior tibial nerves. Local anesthetic is then injected and the spread pattern is observed. Frequently a single injection is sufficient for the local anesthetic to spread around both nerves. Occasionally one or twominor needle adjustmentsmay be required to obtain spread of local anesthetic around both nerves. We believe the advantages of the supine posterior approach are 4-fold: 1) it allows for supine positioning of the patient during block placement, 2) with an out-of-plane approach, the distance the needle tip must travel to the target is shortened, 3) the needle insertion point is adjacent to the transducer, and 4) the popliteal vessels are probably less likely to be traversed, as they are typically located anterior and medial to the nerves. Initially using an out-of-plane needle insertion approach has the disadvantage of poor needle visualization. However, as experience is gainedwith this approach, the anesthesiologistwill be able to discern needle tip location by locating tissue movement, using hydrolocation, or visualizing the tip of the needle. We choose to place the block needle in the space between the common peroneal and posterior tibial nerves for two reasons. First, faster onset may be achieved by blocking the sciatic nerve distal to its bifurcation [3]; and second, we like to think that aiming the block needle towards this fat-filled space (between the nerves)may provide an additionalmargin of safety by avoiding the popliteal vessels as well as minimizing inadvertent needle contactwith nerve(s) (shouldwe be uncertain of the needle tip location given the out-of-plane approach).