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. 2022 Mar 2:9:831778.
doi: 10.3389/fmed.2022.831778. eCollection 2022.

Accuracy of Optic Nerve Sheath Diameter Measurements in Pocket-Sized Ultrasound Devices in a Simulation Model

Garrett G R J Johnson  1 , Tomislav Jelic  2 , Angela Derksen  3 , Bertram Unger  4 , Frederick A Zeiler  5   6   7   8   9 , Markus T Ziesmann  1 , Lawrence M Gillman  1
Affiliations

Accuracy of Optic Nerve Sheath Diameter Measurements in Pocket-Sized Ultrasound Devices in a Simulation Model

Garrett G R J Johnson et al. Front Med (Lausanne). .

Abstract

Introduction: Transorbital sonographic measurement of optic nerve sheath diameter (ONSD) is an emerging non-invasive technique for the identification and monitoring of intracranial hypertension. In recent years, new pocket ultrasound devices have become available, and it is uncertain if they have the resolution to measure such small structures appropriately as compared to their predecessors. In this study, we measure the performance of three ultrasound units on a simulation model to establish their precision and accuracy.

Methods: ONSD was measured by three expert point-of-care sonographers using ultrasound machines three times on each of seven discrete ONS model sizes ranging from 3.5 to 7.9 mm. Two pocket ultrasounds (IVIZ, Sonosite, and Lumify, Philips) and one standard-sized portable ultrasound (M-Turbo, Sonosite) were used. Measurements were analyzed for mean error and variance and tested for significance using blocked covariance matrix regression analyses.

Results: The devices differed in their variances (Lumify: 0.19 mm2, M-Turbo: 0.26 mm2, IVIZ: 0.34 mm2) and their mean error (Lumify: -0.05 mm, M-Turbo: 0.10 mm, IVIZ: -0.10 mm). The difference in mean error between users is not significant (p = 0.45), but there is a significant difference in mean error between devices (p = 0.02).

Conclusions: Accurate ONSD measurement is possible utilizing pocket-sized ultrasound, and in some cases, may be more accurate than larger portable ultrasound units. While the differences in these devices were statistically significant, all three were highly accurate, with one pocket device (Lumify) outperforming the rest. Further study in human subjects should be conducted prior to using pocket ultrasound devices for in vivo diagnosis of intracranial hypertension.

Keywords: intracranial hypertension; intracranial pressure; optic nerve; point-of-care; simulation; ultrasound.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
(A) Simulation model made with a short segment of intravenous or nasogastric tube suspended in gelatin, under a gelatin eyeball. (B) Image of simulation model obtained from Onsite M-turbo (standard sized portable ultrasound) zoomed in with superimposed arrows to highlight measurement technique. (C) Image of simulation model from Sonosite IVIZ (pocket ultrasound) device. (D) Image of simulation model from Philips Lumify (pocket ultrasound) device. All measurements performed at 3 mm behind the simulated orbit. Calipers used to measure distance behind the globe not shown in (C,D).
Figure 2
Figure 2
Box and whisker plot of measurement error (individual observed values minus predicted) stratified by the ultrasound device.
Figure 3
Figure 3
The Box and whisker plot of measurement error (individual observed values minus predicted) stratified by user.
Figure 4
Figure 4
The Box and whisker plot of percent measurement error (individual observed values minus predicted) stratified by predicted size of model optic nerve sheath diameter.
See this image and copyright information in PMC

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