SonixGPS – the role of operator experience

We wish to comment on the performance of the SonixGPS™ needle guidance system in nurse anaesthetists for needle handling in a porcine phantom model, as reported recently by Tielens et al. 1. We studied this system in 30 medical students using a gel phantom model for simulated vascular access 2. Unlike Tielens et al., we did not find a difference in performance between GPS and non-GPS modes for in-plane and out-of-plane approaches. Twenty-six (83%) medical students had no prior experience of ultrasound-guided procedures. In contrast, Tielans et al. state in their discussion that the nurse anaesthetists they recruited had experience comparable with consultants and anaesthesia trainees. Experienced users understand how topographic positioning of the hand and needle correlate with the final objective of visualising the needle tip and task completion. As a result, they are more likely to demonstrate an improvement in performance with the GPS mode. It is therefore surprising why the authors were only able to demonstrate an improvement in performance with GPS during an out-of-plane approach. We were also interested to know whether the authors analysed their data for any ‘learning’ effect based on choice of initial modality. In our study, we noticed that in-plane GPS use led to a statistically significant improvement in time to task completion compared with in-plane non-GPS use (p = 0.013) 2. The authors found ‘ease of use’ scores were better with GPS modality during the out-of-plane approach but not during the in-plane approach. This is in contrast to our findings where the task load scores indicative of ‘ease of use’ were better during GPS versus non GPS for both in-plane and out-of-plane approaches. We wonder if these differences are also a reflection of how novices deal with SonixGPS technology compared with trained nurse anaesthetists. A majority of our students (87%) expressed a preference for the GPS mode as opposed to non-GPS mode for task performance. What were the overall preferences expressed by the nurse anaesthetists in the authors' study? We noticed that the authors placed three Kirschner wires of 0.3 cm diameter within the pork phantom – did they observe any ferromagnetic interference with signals from the SonixGPS and if so how, did they resolve this problem? In our experience, it was not possible to use the SonixGPS on patients who were lying on a metal trolley, due to ferromagnetic interference. Overall, between 27 May 2011 and 30 October 2012, we performed a total of 141 SonixGPS-guided interventions, as summarised in Table 2 3-8. Our experience suggests that the SonixGPS system offers the greatest benefit during out-of-plane interventions and has a useful role for teaching novices.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.