The use of portable 2D echocardiography and 'frame-based' bubble counting as a tool to evaluate diving decompression stress

Peter Germonpré, Virginie Papadopoulou, Walter Hemelryck, Georges Obeid, Pierre Lafère, Robert J. Eckersley, Meng Xing Tang, Costantino Balestra

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Introduction: 'Decompression stress' is commonly evaluated by scoring circulating bubble numbers post dive using Doppler or cardiac echography. This information may be used to develop safer decompression algorithms, assuming that the lower the numbers of venous gas emboli (VGE) observed post dive, the lower the statistical risk of decompression sickness (DCS). Current echocardiographic evaluation of VGE, using the Eftedal and Brubakk method, has some disadvantages as it is less well suited for large-scale evaluation of recreational diving profiles. We propose and validate a new 'frame-based' VGE-counting method which offers a continuous scale of measurement. Methods: Nine 'raters' of varying familiarity with echocardiography were asked to grade 20 echocardiograph recordings using both the Eftedal and Brubakk grading and the new 'frame-based' counting method. They were also asked to count the number of bubbles in 50 still-frame images, some of which were randomly repeated. A Wilcoxon Spearman rho calculation was used to assess test-retest reliability of each rater for the repeated still frames. For the video images, weighted kappa statistics, with linear and quadratic weightings, were calculated to measure agreement between raters for the Eftedal and Brubakk method. Bland-Altman plots and intra-class correlation coefficients were used to measure agreement between raters for the frame-based counting method. Results: Frame-based counting showed a better inter-rater agreement than the Eftedal and Brubakk grading, even with relatively inexperienced assessors, and has good intra- and inter-rater reliability. Conclusion: Frame-based bubble counting could be used to evaluate post-dive decompression stress, and offers possibilities for computer-automated algorithms to allow near-real-time counting.

    Original languageEnglish
    Pages (from-to)5-13
    Number of pages9
    JournalDiving and Hyperbaric Medicine
    Volume44
    Issue number1
    Publication statusPublished - 2014

    Keywords

    • Arterial gas embolism
    • Bubbles
    • Decompression sickness
    • Diving research
    • Doppler
    • Echocardiography
    • Risk assessment
    • Venous gas embolism

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