Thoracic epidural insertion using extended reality hologram assistance: a randomised trial of regional anaesthesia skill performance on the soft embalmed Thiel cadaver

Background
Medical extended reality projects a 3D digital image onto live surface anatomy via a wearable device while allowing operators to interact with the real world. We have developed a 3D hologram of the thoracic spine from CT images of a soft embalmed Thiel cadaver and visualised spinal anatomy through a Microsoft Hololens2 headset. The primary objective of this study was to test whether thoracic epidural training performance on the cadaver was improved using extended reality compared with the landmark insertion technique.

Methods
The study comprised psychometric evaluation of anaesthetists of all grades, a lecture, needling practice on both a plastic simulator, and a soft embalmed Thiel cadaver and familiarisation with the Hololens2. Testing of cadaveric thoracic epidural procedural performance occurred at 10 randomly allocated anatomical sites between T1/2 and T 10/11, randomised equally to the landmark paramedian technique or hologram guidance. Both groups used loss of resistance to fluid as the procedural endpoint. The primary outcome was the log-log slope of Global Rating Scale assessments.

Results
For 58 anaesthetists who completed the study, Global Rating Scale slopes did not differ between groups or by grade of anaesthetist. Secondary endpoints showed differences: the mean log number of needle movements was reduced in the extended reality group: 0.94 (0.95) vs 1.49 (0.97), P<0.001; and ideal performance, defined as a single needle insertion through skin and two or fewer subsequent needle movements, was higher in the extended reality group, 52% vs 28%, Relative Risk (RR) 1.50 (0.91–2.53).

Conclusions
Extended reality hologram-assisted thoracic epidural insertion did not alter Global Rating Scale scores for the holographic vs landmark techniques, but reduced needle movements.