Development and validation of metrics for assessment of ultrasound-guided fascial block skills

Graeme A. McLeod, Jonathan Seeley, Matthew Wilson, Daniel Hind, Ashley Cole, David Hewson, Marie Hyslop, Anju Keetharuth, Alan MacFarlane, Martin Wilby, Mel McKendrick, Gary McKendrick, Ayman Mustafa, Alwin Chuan, Pavan Raju, Nicholas Record, Ines Rombach, Amy Sadler, Liz Swaby, Alasdair TaylorShiva Tripathi, Niamat Aldamluji

Research output: Contribution to journalArticlepeer-review


Lumbar disc surgery is painful. Few anaesthetists provide lumbar erector spinae block for
disc surgery and a need arises to provide training in order to conduct a randomised
controlled investigating pain relief after spinal surgery (NIHR153170).

The primary objective of the study was to measure the construct validity of a checklist for
assessment of skills while performing lumbar and thoracic erector spinae fascial plane
injection in soft embalmed Thiel cadavers. Our secondary objectives were to assess the:
construct validity of a global rating scale; construct validity of pectoral, serratus and fascia
iliaca blocks in the same cadavers; correlation between the checklist and global rating scale;
identify the most important checklist items and measure the variability of our observations.
Twenty-four UK consultant regional anaesthetists completed two iterations of a Delphi
questionnaire. The final checklist consisted of 11 steps conducive to best practice. Thereafter,
we validated the checklist by comparing the performance of 12 experts with 12 novices, each
performing lumbar and thoracic ESP injections; fascia iliaca, serrato-pectoral (PEC II) and
serratus injections, randomly allocated to the left and right sides of 6 soft embalmed Thiel
cadavers. Six expert, trained raters blinded to operator and site of block examined 120 videos

The mean (95%CI:) internal consistency of the 11-item checklist for ESP injection was 0.72
(0.63 – 0.79) and interclass correlation was 0.88 (0.82 – 0.93)
The checklist showed construct validity for lumbar and thoracic erector spinae injection,
experts vs novices (median (IQR [range]) 8.0 (7.0 to 10.0 [1 to 11]) vs 7.0 (5.0 to 9.0 [4 to 11]),
difference 1.5 (1.0 to 2.5) P < 0.001). Global rating scales showed construct validity for
lumbar and thoracic erector spinae injection, 28.0 (24.0 to 31.0 [7 to 35]) vs 21.0 (17.0 to
24.0 [7 to 35]), difference 7.5 (6.0 to 8.5), P < 0.001.

The most difficult items to perform were: identifying the needle tip before advancing the
needle and always visualising the needle tip. Instrument handling and flow of procedure
were the areas of greatest difficulty on the Global Rating Scale. Checklists and GRS scores
correlated. There was homogeneity of regression slopes controlling for status, type of
injection and rater. Generalizability analysis showed a high reliability using the checklist and
GRS for all fascial plane blocks [(Rho (ρ2) 0.93-0.96): Phi (ϕ) (0.84 – 0.87)].

We showed construct validity of an 11-point checklist for fascial plane injection.
Original languageEnglish
JournalBritish Journal of Anaesthesia
Publication statusAccepted/In press - 7 Jun 2024


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