Ultrasound for peripheral nerve blocks
- Edward Yap, MD
Edward Yap, MD
- HS Assistant Professor
- Department of Anesthesia and Perioperative Care, UCSF School of Medicine
- Andrew Gray, MD, PhD
Andrew Gray, MD, PhD
- Professor of Clinical Anesthesia
- UCSF School of Medicine
Ultrasound imaging is increasingly used to guide peripheral nerve blocks. Ultrasound guidance allows real-time visualization of nerves, surrounding structures, and the needle-tip to maximize block success and minimize complications. Unlike other imaging modalities (ie, magnetic resonance imaging [MRI] and computerized tomography [CT]), ultrasound equipment is portable and carries no risk of ionizing radiation.
This topic will discuss the basic principles of ultrasound imaging, the equipment used, and techniques for ultrasound guidance for peripheral nerve block. Ultrasound guidance for venous access, obstetric ultrasound, echocardiography, and other clinical applications for ultrasound are discussed separately. (See "Principles of ultrasound-guided venous access" and "Echocardiography essentials: Physics and instrumentation" and "Ultrasound examination in obstetrics and gynecology".)
Techniques for specific peripheral nerve blocks and other issues common to all peripheral nerve blocks are also discussed separately. (See "Upper extremity nerve blocks: Techniques" and "Lower extremity nerve blocks: Techniques" and "Nerve blocks of the scalp, neck, and trunk: Techniques" and "Overview of peripheral nerve blocks".)
The following are definitions of commonly used ultrasound-related terms.
●Ultrasound – The term "ultrasound" refers to sound waves of a frequency greater than that which the human ear can detect; namely, frequencies greater than 20,000 cycles/second, or Hertz (Hz). Medical imaging requires sound waves of much higher frequency, between 1 and 20 million Hertz (ie, between 1 and 20 megahertz [MHz]).To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:
- Madsen EL, Dong F, Frank GR, et al. Interlaboratory comparison of ultrasonic backscatter, attenuation, and speed measurements. J Ultrasound Med 1999; 18:615.
- Garcia T, Hornof WJ, Insana MF. On the ultrasonic properties of tendon. Ultrasound Med Biol 2003; 29:1787.
- Soong J, Schafhalter-Zoppoth I, Gray AT. The importance of transducer angle to ultrasound visibility of the femoral nerve. Reg Anesth Pain Med 2005; 30:505.
- Goldstein A, Madrazo BL. Slice-thickness artifacts in gray-scale ultrasound. J Clin Ultrasound 1981; 9:365.
- Lin DC, Nazarian LN, O'Kane PL, et al. Advantages of real-time spatial compound sonography of the musculoskeletal system versus conventional sonography. AJR Am J Roentgenol 2002; 179:1629.
- Szabo TL, Lewin PA. Ultrasound transducer selection in clinical imaging practice. J Ultrasound Med 2013; 32:573.
- Karmakar MK, Li JW, Kwok WH, et al. Sonoanatomy relevant for lumbar plexus block in volunteers correlated with cross-sectional anatomic and magnetic resonance images. Reg Anesth Pain Med 2013; 38:391.
- Swenson JD, Klingler KR, Pace NL, et al. Evaluation of a New Needle Guidance System for Ultrasound: Results of a Prospective, Randomized, Blinded Study. Reg Anesth Pain Med 2016; 41:356.
- Gray AT. Ultrasound-guided regional anesthesia: current state of the art. Anesthesiology 2006; 104:368.
- Filly RA, Sommer FG, Minton MJ. Characterization of biological fluids by ultrasound and computed tomography. Radiology 1980; 134:167.
- Maturen KE, Wasnik AP, Bailey JE, et al. Posterior acoustic enhancement in hepatocellular carcinoma. J Ultrasound Med 2011; 30:495.
- Gray AT, Schafhalter-Zoppoth I. "Bayonet artifact" during ultrasound-guided transarterial axillary block. Anesthesiology 2005; 102:1291.
- Turnbull DH, Wilson SR, Hine AL, Foster FS. Ultrasonic characterization of selected renal tissues. Ultrasound Med Biol 1989; 15:241.
- Silvestri E, Martinoli C, Derchi LE, et al. Echotexture of peripheral nerves: correlation between US and histologic findings and criteria to differentiate tendons. Radiology 1995; 197:291.
- SUNDERLAND S. The relative susceptibility to injury of the medial and lateral popliteal divisions of the sciatic nerve. Br J Surg 1953; 41:300.
- Hörmann M, Traxler H, Ba-Ssalamah A, et al. Correlative high-resolution MR-anatomic study of sciatic, ulnar, and proper palmar digital nerve. Magn Reson Imaging 2003; 21:879.
- Schafhalter-Zoppoth I, McCulloch CE, Gray AT. Ultrasound visibility of needles used for regional nerve block: an in vitro study. Reg Anesth Pain Med 2004; 29:480.
- Hopkins RE, Bradley M. In-vitro visualization of biopsy needles with ultrasound: a comparative study of standard and echogenic needles using an ultrasound phantom. Clin Radiol 2001; 56:499.
- THE WAY ULTRASOUND WORKS
- ULTRASOUND EQUIPMENT
- Ultrasound machines
- - Spatial compound imaging
- - Doppler modes
- ULTRASOUND TECHNIQUE
- Preparation for scanning
- - Ergonomics
- - Time out
- - Gel
- - Scout scan
- - Sterile technique
- Needle orientation
- Ultrasound artifacts
- Image acquisition
- - Transducer manipulation
- - Finding the nerve or space
- - Optimizing the image
- Manipulating the transducer
- Minimizing artifact
- Maximizing machine settings
- - Visualizing the needle
- Injection of local anesthetic
- SUMMARY AND RECOMMENDATIONS