VOLUME 29, Issue 1

Several recent publications have compared the efficacy between UGRA and NSRA. Liu’s review ^[1] concluded that UGRA produced a non-inferior block success rate with potential patient-oriented benefits such as faster block performance, fewer needle passes, less local injections, less patient discomfort, and a non-significant difference in side effects from block performance. Recent prospective studies by Thomas, Meierhoferl, and Farag separately associated USRA with less procedural time and thus less economic cost ^[2-4]. Luyet ^[5] and Maalouf ^[6] reported less local anesthetic volumes while using ultrasound guidance. No difference was found between UGRA and NSRA in post op pain ^[2,4,6], post op analgesic requirements ^[2,4,6], length of stay ^[4], and patient satisfaction ^[2,3,7].

Onset of surgical anesthesia continued to be controversial as Thomas ^[2] reported faster time to onset of nerve block with UGRA, while no significant difference was identified by Meierhofer ^[3] and Liu ^[7]. Finally, Orebaugh ^[8] retrospectively analyzed over five thousand nerve blocks and reported that eight block-related adverse events (five seizures and three nerve injuries) were associated with 3290 nerve stimulator blocks while none was associated with 2146 ultrasound-guided blocks. Subgroup analysis by Orebaugh ^[8] concluded that upper extremity NSRA was weakly associated with seizure (4/988 in NSRA vs. 0/1313 in UGRA, P=0.044), while no association was found between anesthesia techniques and major neurologic injury. The data suggests that in the hands of experienced providers, UGRA resulted in slightly more favorable adverse event profiles while consistently provided more patient-oriented benefits compared to NSRA.

Despite well-documented novice behaviors creating difficult learning curves with ultrasound, several publications have investigated on the success of early trainee experience with ultrasound-guided nerve blocks. Williams established prospectively that senior trainees with prior regional anesthesia experiences utilized UGRA at a faster pace compared to NSRA ^[8]. Sites suggested that ultrasound guidance allowed a reduction in procedure time by 30% and 40% on the second and third attempts, respectively ^[9]. Orebaugh reported in his retrospective study that trainees performing nerve blocks using both ultrasound and nerve stimulator had less procedure time and fewer needle passes than with only nerve stimulator ^[10]. In another retrospective analysis, Luyet ^[5] showed higher block success when using UGRA after 10, 20, 30, or after 40 blocks in novice anesthetic providers compared to NSRA.

On the other hand, a 2011 prospective randomized controlled trial by Thomas ^[2] concluded that shorter procedure time, faster onset of surgical anesthesia, and longer anesthetic duration were achieved by inexperienced trainees using UGRA despite equivalent block success rate between UGRA and NSRA. Additionally, multiple nerve block studies involving early trainees using ultrasound noted significantly fewer surrogates of adverse events, such as intravascular punctures ^{[5, 10]}. Suffice to say, novice behavior is not a limitation for UGRA performance in trainees who are also equally inexperienced in NSRA.

The debate remains: should graduating residents rely solely on ultrasound- guided regional anesthesia training, as in many residency programs? Or should residents be trained in both techniques, even though ultrasound-guided regional anesthesia offers multiple advantages over nerve stimulation? The future may hold that proficiency in ultrasound-guided techniques is sufficient with the number of surgical centers without available ultrasound machines rapidly dwindling. However, current graduating residents are still getting jobs at centers that practice regional anesthesia without ultrasound capability. In addition to all of the current residency training in UGRA, it is our opinion that programs should still make an effort to teach some nerve blocks with nerve stimulation.

Learning some of the “bread-and-butter” blocks using nerve stimulation such as femoral and interscalene blocks, commonly used to treat pain after knee and shoulder surgery, would be of great benefit to anesthesiologists working in outpatient centers. In addition, learning how to use nerve stimulation for axillary and sciatic blocks in the popliteal fossa would also be helpful. Furthermore, by training with nerve stimulator techniques, trainees may benefit from learning the superficial anatomy and landmarks to determine optimal skin puncture – a lost art with the almost exclusive use of ultrasound guidance. Despite weak evidence on superior outcome of ultrasound over nerve stimulator, the complementary nature of UGRA and NSRA should promote programs to train residents in both techniques to provide regional anesthetic care in all parts of the country, as current practicing environment suggested.

References:

1. Liu SS, Ngeow JE, Yadeau JT. Ultrasound-guided regional anesthesia and analgesia: A qualitative systematic review. Reg Anesth Pain Med 2009; 34: 47-59.
2. Thomas LC, Graham SK, Osteen KD, Porter HS, Nossaman BD. Comparison of ultrasound and nerve stimulation techniques for interscalene brachial plexus block for shoulder surgery in a residency training environment: a randomized, controlled, observerblinded trial. Ochsner J. 2011 Fall; 11: 246-52.
3. Meierhofer JT, Anetseder M, Roewer N, Wunder C, Schwemmer U. Guidance of axillary multiple injection technique for plexus anesthesia: Ultrasound versus nerve stimulation. Anaesthesist. 2014 Jul; 63: 568-73.
4. Farag E, Atim A, Ghosh R, Bauer M, Sreenivasalu T, Kot M, Kurz A, Dalton JE, Mascha EJ, Mounir-Soliman L, Zaky S, Ali Sakr Esa W, Udeh BL, Barsoum W, Sessler DI. Comparison of three techniques for ultrasound-guided femoral nerve catheter insertion: a randomized, blinded trial. Anesthesiology 2014; 121: 239-48.
5. Luyet C, Schüpfer G, Wipfli M, Greif R, Luginbühl M, Eichenberger U. Different Learning Curves for Axillary Brachial Plexus Block: Ultrasound Guidance versus Nerve Stimulation. Anesthesiology Research and Practice 2010; 2010:309462.
6. Maalouf D, Liu SS, Movahedi R, Goytizolo E, Memtsoudis SG, Yadeau JT, Gordon MA, Urban M, Ma Y, Wukovits B, Marcello D, Reid S, Cook A. Nerve stimulator versus ultrasound guidance for placement of popliteal catheters for foot and ankle surgery. J Clin Anesth 2012; 24: 44-50.
7. Liu SS, Zayas VM, Gordon MA, Beathe JC, Maalouf DB, Paroli L, Liguori GA, Ortiz J, Buschiazzo V, Ngeow J, Shetty T, Ya Deau JT. A prospective, randomized, controlled trial comparing ultrasound versus nerve stimulator guidance for interscalene block for ambulatory shoulder surgery for postoperative neurological symptoms. Anesth Analg 2009; 109: 265-71.
8. Williams SR, Chouinard P, Arcand G, Harris P, Ruel M, Boudreault D, Girard F. Ultrasound guidance speeds execution and improves the quality of supraclavicular block. Anesth Analg 2003; 97: 1518-23.
9. Sites BD, Gallagher JD, Cravero J, Lundberg J, Blike G. The learning curve associated with a simulated ultrasound-guided interventional task by inexperienced anesthesia residents. Reg Anesth Pain Med 2004; 29: 544-8.
10. Orebaugh SL, Williams BA, Kentor ML. Ultrasound guidance with nerve stimulation reduces the time necessary for resident peripheral nerve blockade. Reg Anesth Pain Med 2007; 32: 448-454.