title: Doppler ultrasound surveillance in deep tunneling compressed-air work with Trimix breathing: bounce dive technique compared to saturation-excursion technique.
abstract: The Western Scheldt Tunneling Project in The Netherlands provided a unique opportunity to evaluate two deep-diving techniques with Doppler ultrasound surveillance. Divers used the bounce diving techniques for repair and maintenance of the TBM. The tunnel boring machine jammed at its deepest depth. As a result the work time was not sufficient. The saturation diving technique was developed and permitted longer work time at great depth. Thirty-one divers were involved in this project. Twenty-three divers were examined using Doppler ultrasound. Data analysis addressed 52 exposures to Trimix at 4.6-4.8 bar gauge using the bounce technique and 354 exposures to Trimix at 4.0-6.9 bar gauge on saturation excursions. No decompression incidents occurred with either technique during the described phase of the project. Doppler ultrasound revealed that the bubble loads assessed in both techniques were generally low. We find out, that despite longer working hours, shorter decompression times and larger physical workloads, the saturation-excursion technique was associated with significant lower bubble grades than in the bounce technique using Doppler Ultrasound. We conclude that the saturation-excursion technique with Trimix is a good option for deep and long exposures in caisson work. The Doppler technique proved valuable, and it should be incorporated in future compressed-air work.
authors.affiliation: Coronel Institute of Occupational Health, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: T P van Rees
authors.initials: TP
authors.lastname: Vellinga
authors.forename: W
authors.initials: W
authors.lastname: Sterk
authors.forename: A G E M
authors.initials: AG
authors.lastname: de Boer
authors.forename: A J
authors.initials: AJ
authors.lastname: van der Beek
authors.forename: A C
authors.initials: AC
authors.lastname: Verhoeven
authors.forename: F J H
authors.initials: FJ
authors.lastname: van Dijk
mesh_terms: D000328:Adult; D015992:Body Mass Index; D020378:Confined Spaces; D003664:Decompression / Q000379:methods; D003665:Decompression Sickness / Q000000981:diagnostic imaging*; D004242:Diving / Q000502:physiology*; D004738:Engineering; D006371:Helium / Q000008:administration & dosage*; D006801:Humans; D009426:Netherlands; D009584:Nitrogen / Q000008:administration & dosage*; D010100:Oxygen / Q000008:administration & dosage*; D012449:Safety; D013997:Time Factors; D014463:Ultrasonography; D014940:Work Schedule Tolerance / Q000502:physiology; D016526:Workload
chemical_list: D006371:Helium; C045257:trimix; D009584:Nitrogen; D010100:Oxygen