The Shamrock lumbar plexus block: A dose-finding study

Axel R. Sauter*, Kyrre Ullensvang, Geir Niemi, Havard T. Lorentzen, Thomas Fichtner Bendtsen, Jens Børglum, Are Hugo Pripp, Luis Romundstad

*Corresponding author af dette arbejde

Publikation: Bidrag til tidsskriftArtikelForskningpeer review


BACKGROUND The Shamrock technique is a new method for ultrasound-guided lumbar plexus blockade. Data on the optimal local anaesthetic dose are not available. OBJECTIVE The objective of this study is to estimate the effective dose of ropivacaine 0.5% for a Shamrock lumbar plexus block. DESIGN A prospective dose-finding study using Dixon's upand- down sequential method. SETTING University Hospital Orthopaedic Anaesthesia Unit. INTERVENTION Shamrock lumbar plexus block performance and block assessment were scheduled preoperatively. Ropivacaine 0.5% was titrated with the Dixon and Massey up-and-down method using a stepwise change of 5ml in each consecutive patient. Combined blocks of the femoral, the lateral femoral cutaneous and the obturator nerve were prerequisite for a successful lumbar plexus block. PATIENTS Thirty patients scheduled for lower limb orthopaedic surgery completed the study. MAIN OUTCOME MEASURES The minimum effective anaesthetic volume of ropivacaine 0.5% (ED50) to achieve a successful Shamrock lumbar plexus block in 50% of the patients. Further analysis of the data was performed with a logistic regression model to calculate ED95 and to estimate the effective doses for a sensory lumbar plexus block not requiring a motor block of the femoral nerve. RESULTS The Dixon and Massay estimate of the ED50 was 20.4 [95% confidence interval (95% CI) 13.9 to 30.0] ml ropivacaine 0.5%. The logistic regression estimate of theED95 was 36.0 (95% CI 19.7 to 52.2) ml ropivacaine 0.5%. For a sensory lumbar plexus block, the ED50 was 17.1 (95%CI 12.3 to 21.9) ml and the ED95 was 25.8 (95% CI 18.6 to 33.1) ml. CONCLUSION A volume of 20.4 ml ropivacaine 0.5% provided a successful Shamrock lumbar plexus block in 50% of the patients. A volume of 36.0 ml would be successful in 95% of the patients. TRIAL REGISTRATION identifier NCT01956617.

Sider (fra-til)764-770
Antal sider7
TidsskriftEuropean Journal of Anaesthesiology
Udgave nummer11
StatusUdgivet - nov. 2015


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