Novel 3D-ultrasound-guided midline lumbar epidural placement, utilizing Epiguide needle guide in porcine model: a comparison of standard versus Pajunk epidural needles
Abstract Number: F-34
Abstract Type: Original Research
Introduction: We developed a real-time 3D ultrasound (3DUS) thick slice rendering technique and innovative Epiguide needle-guide as an adjunct to single-operator midline epidural needle insertions. Study goals: determine feasibility of the technique in a pig model and compare visibility of standard (SN) and echogenic needle (EN).
Methods: 37 lumbar needle insertions were performed on 6 intact porcine spines ex vivo. Puncture sites were first identified by palpation. The ligamentum flavum (LF) was then identified using 3DUS (Ultrasonix, Canada). Using the Epiguide, the needle was guided into the epidural space in the midline plane, watched in real-time on the 3DUS. Success was judged by achieving a loss of resistance (LOR) to fluid. Palpation site to puncture site distance, and insertion depth from needle tip to a zero-mark on the Epiguide were recorded. Needle visibility was rated by the anesthetist performing epidural using a 4-point scale^1 (0=cannot see, 1=poor, 2=satisfactory, 3=excellent). This was repeated at multiple randomly-selected lumbar levels using the SN and EN (Pajunk®, Germany). Images were saved and needle visibility was later rated by a blinded assessor. Calibrated 3DUS depth from zero point to LF was also measured.
Results: Successful LOR was achieved in 78% of needle insertions; 100% success when needle visibility was ‘excellent’ (Fig. 1). Needle visibility with EN (2.4±0.6, 94.4% satisfactory/excellent) was significantly greater than SN (0.6±0.7, 10.5% satisfactory/excellent) at p<0.001. Inter-observer agreement was good (Kappa=0.68). Mean distance between palpated puncture site and 3DUS guided insertion was 3.3±4.4mm. Insertion depth was greater than 3DUS depth to the LF (8.5±5.4mm).
Discussion: It is feasible to perform 3DUS-guided real-time single-operator midline epidural insertions, with EN consistently improving both needle visibility and successful LOR. Insertion depth error is consistent with previous work on ultrasound^2, and can be explained by the thickness of the rendered LF (5.4±1.2 mm), and small overshoot of the needle past LF. It is recommended that 3DUS, together with Epiguide, be used to aid both the selection of puncture sites and the needle trajectory, but LOR should be used as the endpoint of insertion into the epidural space.
1:Gofield M et al., Pain Phys, 2013;16(6):725-730.
2:Tran D, Rohling R, IEEE Biomed Eng, 2010;57(9), 2248-2256.