Assessing the Effect of Augmented Reality on Procedural Outcomes During Ultrasound-Guided Vascular Access

Abstract

Objective: Augmented reality devices are increasingly accepted in health care, though most applications involve education and pre-operative planning. A novel augmented reality ultrasound application, HoloUS, was developed for the Microsoft HoloLens 2 to project real-time ultrasound images directly into the user's field of view. In this work, we assessed the effect of using HoloUS on vascular access procedural outcomes.

Methods: A single-center user study was completed with participants with (N = 22) and without (N = 12) experience performing ultrasound-guided vascular access. Users completed a venipuncture and aspiration task a total of four times: three times on study day 1, and once on study day 2 between 2 and 4 weeks later. Users were randomized to use conventional ultrasound during either their first or second task and the HoloUS application at all other times. Task completion time, numbers of needle re-directions, head adjustments and needle visualization rates were recorded.

Results: For expert users, task completion time was significantly faster using HoloUS (11.5 s, interquartile range [IQR] = 6.5-23.5 s vs. 18.5 s, IQR = 11.0-36.5 s; p = 0.04). The number of head adjustments was significantly lower using the HoloUS app (1.0, IQR = 0.0-1.0 vs. 3.0, IQR = 1.0-5.0; p < 0.0001). No significant differences were identified in other measured outcomes.

Conclusion: This is the first investigation of augmented reality-based ultrasound-guided vascular access using the second-generation HoloLens. It demonstrates equivalent procedural efficiency and accuracy, with favorable usability, ergonomics and user independence when compared with traditional ultrasound techniques.

Keywords: Augmented reality; Head-mounted display; HoloLens; Ultrasound guidance; Vascular access.

Fig. 1

The two main modules of the HoloUS application: the transmit and display modules. The HoloUS application communicates wirelessly with the ultrasound machine and HoloLens 2 device to render holographic ultrasound images and register them in space with an augmented reality marker on the ultrasound transducer.

Fig. 2

Photos of a HoloUS user’s view taken with the HoloLens 2 camera. The holographic ultrasound image as well as the physical surroundings are shown as they appear to the user. In Tracking Mode (A), the default ultrasound image location is directly beneath the ultrasound transducer in its corresponding anatomical position based on tracking of 3D-printed ArUco markers. HoloUS “tracks” the transducer and automatically adjusts the image location. In Floating Mode (B), the default ultrasound image location is directly in the user’s line of sight. The image position can be adjusted with voice commands based on the user’s preference.

Fig. 3

The 3-vessel vascular phantom used for the user study (A, B). Users were instructed to target the center of the vessel prior to its bifurcation (C, D). Simultaneous photos taken by an external observer and digital camera (C) and by the user and the HoloLens’ camera (D) are shown. User study timeline (E).

Fig. 4

Task outcome results for all users (A – E, N = 32) and expert users (F – J, N = 20). Task completion time in seconds (A, F), number of attempts (B, G), number of needle redirections (C, H), number of head adjustments (D, I), and needle visualization rate (E, J) (%). Time is plotted as median ± interquartile range (A, F) (IQR), all others plotted as mean ± SEM (B – E, G – J). * = P < 0.05, ** = P < 0.01, *** = P < 0.001, **** = P < 0.0001.

Fig. 5

NASA-Task Load Index (TLX) survey results by specialty and level of training. Total score (A) as well as mental (B), physical (C), temporal (D), performance (E), effort (F), and frustration (G) outcome measures were analyzed.