Neurostimulation in ultrasound guided interscalene catheter placement: a comparison of an ultrasound and neurostimulation needle endpoint
Michael Fredrickson
Auckland City Hospital, Auckland, New Zealand
Introduction: Neurostimulation during single shot interscalene block has a < 100% sensitivity for close needle-nerve proximity as assessed by ultrasound. 1 Compared to single shot block, interscalene catheter (ISC) placement commonly involves Tuohy needles inserted longitudinally to the brachial plexus. 2 This study aimed compare an ultrasound and a neurostimulation needle endpoint for ISC placement.
Materials and Methods: 44 consecutive patients presenting to the author for elective shoulder surgery. Non-stimulating ISCs placed under ultrasound guidance. Needle tip position prospectively randomized to ultrasound or < 0.5 mA needle endpoint. Neurostimulation not used in ultrasound group. Catheters advanced blindly via a Raulerson syringe 2-3 cm past needle tip. Anaesthesia conduct and ISC ambulatory management as previously described. 2 ISC needle times under the skin (as an indirect measure of needle manipulations), pain score during insertion and indices of ISC effectiveness during the first 48 postoperative hours recorded.
Results: One patient in the ultrasound group excluded because of failure to obtain satisfactory ultrasound image - necessitated < 0.5 mA needle endpoint. Ultrasound needle endpoint associated with reduced needle time under the skin (p = 0.024). Pain scores during ISC insertion and indices of ISC effectiveness similar in both groups.
Conclusions: An ultrasound guided ISC needle endpoint is a feasible alternative to a neurostimulation endpoint and may enable a reduction in the number of needle manipulations required for accurate placement.
References
- Sinha SK: Anesth Analg 2007; 105: 848
- Fredrickson MJ: Reg Anesth Pain Med 2008; 33 (2)
