Translation of sonoelastography from Thiel cadaver to patients for peripheral nerve blocks*

Abstract

SummaryUltrasound guidance is now common in regional anaesthesia practice, but remains limited by poor visibility of the needle tip and poor quantification of local anaesthetic spread. Sonoelastography based on tissue compression is a technique depicting tissue strain. Hitherto used largely for tumour diagnosis, we used it in both Thiel embalmed cadavers and two patients receiving interscalene and femoral blocks to observe changes in tissue strain during local anaesthetic injection. The primary aim of our study was to measure the area under the curve (weighted for time) of the strain pattern in Thiel perineural tissue when using a range of volumes of embalming fluid (0.25, 0.5, 1, 2.5, 5 and 7.5 ml) for interscalene and femoral blocks using sonoelastography. Our secondary aims were to evaluate static images of anatomy and videos of needle insertion and perineural injection using combined B-Mode ultrasound and sonoelastography. Independent raters assessed the anatomy and spread using a 7-point Likert scale, ranked from extremely poor to extremely good. We performed 83 blocks in cadavers. Concordance between both raters was good, with weighted Kappa (95% CI) 0.66 (0.61-0.71). The characteristics of spread were similar with both interscalene and femoral block; spread increased with injectate volume up to 1 ml. Analysis of variance showed differences in spread between injection volumes (p = 0.009), but not between regional blocks (p = 0.05). Post-hoc analysis showed greater spread with 1 and 2.5 ml volumes compared with 0.25 ml. In patients, visibility of strain during injection was better with sonoelastography than with B-Mode ultrasound and showed a dose response from 1 to 5 ml volumes of local anaesthetic. Colour strain recognition using sonoelastography offers the ability to differentiate between nerve and surrounding tissue during local anaesthetic injection by improving visibility of spread (p = 0.04).

Comparison of modified thiel embalming and ethanol‐glycerin fixation in an anatomy environment: Potentials and limitations of two complementary techniques

“…However, the financial efforts have to be weighed against the tissue characteristics resulting from the fixation agents. As shown in our study and by others (Thiel, ; Wolff et al, ; Benkhadra et al, ; Pattanshetti and Pattanshetti, ; Jaung et al, ; Hölzle et al, ; Munirama et al, ; Prasad et al, ; Eisma et al, ), Thiel‐fixed donors provide outstanding visual and haptic properties. Our modifications may likely aid saving costs in order to make the Thiel technique available to a broader user group (Benkhadra et al, ).…”

“…The wide range of joint motion allows orthopedic and trauma surgeons to perform interventions under realistic conditions, which is not the case after ethanol and formaldehyde fixation. Thiel fixation is also suitable for training laparoscopic techniques (Pattanshetti and Pattanshetti, ; Prasad et al, ) and ultrasound‐assisted interventions such as biopsies and nerve blocks (Munirama et al, ). Even muscle‐ or skin‐flaps can be accomplished by head and neck (Alberty et al, ), plastic (Wolff et al, ), oral surgeons and implantologists (Hölzle et al, ), since the Thiel fixatives prevent blood clot formation.…”

Benefits and pitfalls of cadavers as learning tool for ultrasound-guided regional anesthesia

“…used sonoelastography to study the interstitial, intra-arterial, and intraneural spread of local anesthetics in Thiel cadavers and found that these can be used for objective assessment of the learning. [827] These cadavers can also be used for testing new technology and developing new techniques in UGRA. [5]…”

Walter Thiel's Embalming Method: Review of Solutions and Applications in Different Fields of Biomedical Research

“…Studies have been done on a supraomohyoid plexus block to avoid complications or collateral effects on other nerves (Feigl et al, 2006) and the spread of local anesthetic to block peripheral nerves (Munirama et al, 2012). For their part, Feigl et al (2013b), identified a simple orientation mark to carry out the vertical obturator nerve block.…”