Anesth Analg 2006;102:649
© 2006 International Anesthesia Research Society
doi: 10.1213/01.ANE.0000190746.29732.12
LETTER TO THE EDITOR
Not All Reasons for Difficult Peripheral Nerve Blocks Are at the Proximal End of the Needle
Matthias Hübler, MD, DEEA, and
Sebastian N. Stehr, MD
Department of Anesthesiology, University Hospital Carl Gustav Carus, Technical University Dresden, Dresden, Germany, matthias.huebler{at}uniklinikum-dresden.de
To the Editor:
We would like to report an unusual case of equipment failure during peripheral nerve blockade. A very obese female patient (body mass index, 60.1) was scheduled for endoprosthetic knee surgery under peripheral nerve blockade. In the anesthesia induction room the patient was placed in the lateral decubitus position. After disinfection and local anesthesia of the appropriate skin areas, the sciatic nerve was located using the posterior approach. We used our standard nerve stimulator (B. Braun AG, Melsungen, Germany) and a 150-mm insulated needle with facet tip (19.5-gauge; Pajunk GmbH, Geisingen, Germany) aiming at intensity <0.5 mA with a pulse width of 0.1 ms. After injection of the local anesthetic, the needle was withdrawn. The identification of the lumbar plexus was then performed with the same needle using the posterior lumbar approach as described for psoas compartment blockade (1). Because of the very challenging anatomy, several attempts were necessary to identify the transverse spinal processus. Finally, the processus was identified in a distance to skin of 9 cm. The needle’s position was corrected cranially and advanced 3 cm more. The electric stimulation of the lumbar plexus was confirmed by quadriceps muscle contractions. Unfortunately, the stimulation energy could not be decreased to <0.9 mA (pulse width 0.1 ms). We attempted to optimize the needle’s position, aiming for an electric intensity <0.5 mA. To do this, the needle was withdrawn to the subcutis and advanced again ... and again ... and again ..., but a muscular response was not observed. Finally, we decided to give up. After removal of the needle, we inspected its tip very closely and were very surprised to observe that parts of the insulation were missing (Fig. 1). Using a new needle and already knowing the patient’s anatomy, the lumbar plexus was located easily.
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Figure 1. The two photos on the left side show the tip of a used catheter. The two photos on the right side show the tip of the catheter, with which we were unable to obtain a muscular response.
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This unusual case emphasizes that the insulation of peripheral stimulation needles should be inspected closely if they are used for numerous attempts. Usually, failure to perform peripheral regional anesthesia is attributed to the proximal end of the needle because the material is considered to be indestructible. We were glad that for once, this was not the case.
Reference
- Capdevila X, Macaire P, Dadure C, et al. Continuous psoas compartment block for postoperative analgesia after total hip arthroplasty: new landmarks, technical guidelines, and clinical evaluation. Anesth Analg 2002;94:1606-13.[Abstract/Free Full Text]
