Minerva Anestesiologica 2021 Feb 16

DOI: 10.23736/S0375-9393.21.15012-6

Copyright © 2021 EDIZIONI MINERVA MEDICA

lingua: Inglese

Determination of the initial minimum effective dose of 0.5% bupivacaine with 20mcg of fentanyl for an operative fixation of fractured neck of femur. A prospective, observational trial

Tomas HITKA ¹ ✉, Jane O'SULLIVAN ², Szilard SZUCS ³, Gabriella IOHOM ⁴

¹ Clinical Fellow in Regional Anaesthesia, Department of Anaesthesia and Intensive Care, Cork University Hospital, Cork, Ireland; ² Anaesthesia SHO, Department of Anaesthesia and Intensive Care, Tallaght University Hospital, Dublin, Ireland; ³ Clinical Lecturer, Department of Anaesthesia and Intensive Care, Cork University Hospital, Cork, Ireland; ⁴ Consultant Anaesthetist and Senior Lecturer, Cork University Hospital and University College Cork, Cork, Ireland

BACKGROUND: Fractured Neck of femur (FNF) is a common cause of morbidity and mortality in elderly. Spinal catheter allows fractionation of local anaesthetic dose which combined with intrathecal opioid leads to a dose reduction and better haemodynamic stability. The primary objective is to investigate the initial minimum local anaesthetic dose (iMLAD) of 0.5% isobaric bupivacaine with 20mcg of fentanyl administered via spinal catheter in order to commence the operative fixation of FNF.
METHODS: A prospective, single-blinded, adaptive clinical trial with patients undergoing dynamic hip screw implantation (DHS) or hemiarthroplasty (HEMI) due to FNF. The Dixon and Massey’s up and down method was used to determine the ED50 of intrathecal bupivacaine. This figure was confirmed with Probit analysis, in addition to the ED95.
RESULTS: Using the Dixon and Massey’s approach, the iMLADED50 for DHS was 0.29 ml (1.45mg) and the iMLADED50 for HEMI was 0.33 ml (1.65mg) of 0.5% isobaric bupivacaine. The Probit analyses demonstrated that the iMLADED95 for DHS and HEMI were 0.32 ml (1.6mg) and 0.34ml (1.7mg) respectively. The mean cumulative dose of 0.5% bupivacaine for the whole surgery was 0.67 ml (3.35mg) and 0.87 ml (4.35mg) in the DHS and HEMI groups respectively.
CONCLUSIONS: This study demonstrates that the placement of a spinal catheter allows for careful titration of local anaesthetic, enabling a reduction of the initial intrathecal dose of 0.5% isobaric bupivacaine below 0.4ml (2mg) and leading to a significant reduction of a dose required for the whole surgery when combined with an intrathecal opioid.

KEY WORDS: Neuraxial anaesthesia; Spinal catheter; Femoral neck fracture