Anesth Analg 2006;103:1038-1039
© 2006 International Anesthesia Research Society
doi: 10.1213/01.ane.0000239015.88751.b2
LETTER TO THE EDITOR
Editor-in-Chief Steven L. Shafer
In Defense of the Peripheral Nerve Stimulation Technique
Denis Jochum,
Gabriella Iohom,
Louis-Jean Dupré, and
Hervé Bouaziz
Department of Anesthesiology; Private Hospital Group of Center Alsace; Colmar, France (Jochum)
Department of Anesthesiology; Cork University Hospital; Cork, Ireland (Iohom)
Department of Anesthesiology; Clinique Cléret; Chambéry, France (Dupré)
Department of Anesthesiology; University Hospitals; Nancy, France; h.bouaziz{at}chu-nancy.fr (Bouaziz)
To the Editor:
Voelckel et al. (1) recently demonstrated an increased risk of nerve damage when nerve stimulators elicit a motor block at current intensities below 0.2 mA. The minimal current to produce an effective block is unknown. It can be defined as the value below which an appropriate motor response is no longer obtained after a search within the three axes of space (2). A systematic search for the minimum current may reduce the risk of neural injury (3). Jochum et al. (4) showed a correlation between the minimal stimulating current and success rate, but never recommended eliciting a motor response with stimulating current intensities as low as 0.1–0.2 mA.
Using a nerve stimulator requires precision and knowledge of its performance characteristics, particularly in the low-current range. The authors chose a relatively long impulse duration of 0.3 ms. Pither et al. (5) pointed out that impulses of short duration provide better discrimination between observed responses.
In our view, optimal needle localization should be based on a combination of criteria (4) rather than relying on minimum current intensity alone. These criteria include the minimal current intensity of a defined duration delivered via an unrestrained and immobile needle, the sensation of penetrating the relevant fascia, a clear motor end point, the disappearance of a muscular contraction following the injection of 1 mL of local anesthetic solution, the ease of reproducing this contraction by increasing once more the current intensity, and painless injection without resistance. It is hard to know whether these were taken into account in this experimental study design. It is under these conditions that it will be possible on one hand to further improve the risk–benefit ratio of nerve stimulation, and on the other hand to establish predictors of success that will enhance our practice.
REFERENCES
- Voelckel WG, Klima G, Krismer AC, et al. Signs of inflammation after sciatic nerve block in pigs. Anesth Analg 2005;101:1844–6.[Abstract/Free Full Text]
- Dupré LJ. Neurostimulateur en anesthésie loco-régionale [The neurostimulator in loco- regional anesthesia]. Cah Anesthésiol 1992;40:503–10.[Medline]
- Peripheral nervous blocks in adults. Recommendations for clinical practice. French Society of Anesthesia and Intensive Care, 2003. Available at www.sfar.org.
- Jochum D, Roedel R, Gleyze P, Balliet JM. Bloc interscalénique et chirurgie de l'épaule. Etude prospective d'une série continue de 167 patients [Interscalenic block and surgery of the shoulder: a prospective study of a continuous series of 167 patients]. Ann Fr Anesth Reanim 1997;16:114–9.[Web of Science][Medline]
- Pither CE, Raj PP, Ford DJ. The use of peripheral nerve stimulators for regional anesthesia. A review of experimental characteristics, technique and clinical applications. Reg Anesth 1985;10:49–58.
|
