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A Metabolic Simulator for Unmanned Testing of Breathing Apparatuses in Hyperbaric Conditions
KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology.
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2014 (English)In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 85, no 11, 1139-1144 p.Article in journal (Refereed) Published
Abstract [en]

Background: A major part of testing of rebreather apparatuses for underwater diving focuses on the oxygen dosage system. Methods: A metabolic simulator for testing breathing apparatuses was built and evaluated. Oxygen consumption was achieved through catalytic combustion of propene. With an admixture of carbon dioxide in the propene fuel, the system allowed the respiratory exchange ratio to be set freely within human variability and also made it possible to increase test pressures above the condensation pressure of propene. The system was tested by breathing ambient air in a pressure chamber with oxygen uptake (VO2) ranging from 1-4 L.min(-1), tidal volume (V-T) from 1-3 L, breathing frequency (f) of 20 and 25 breaths/min, and chamber pressures from 100 to 670 kPa. Results: The measured end-tidal oxygen concentration (FO2) was compared to calculated end-tidal FO2. The largest average difference in end-tidal FO2 during atmospheric pressure conditions was 0.63%-points with a 0.28%-point average difference during the whole test. During hyperbaric conditions with pressures ranging from 100 to 670 kPa, the largest average difference in FO2 was 1.68%-points seen during compression from 100 kPa to 400 kPa and the average difference in FO2 during the whole test was 0.29%-points. Conclusion: In combination with a breathing simulator simulating tidal breathing, the system can be used for dynamic continuous testing of breathing equipment with changes in V-T, f, VO2, and pressure.

Place, publisher, year, edition, pages
2014. Vol. 85, no 11, 1139-1144 p.
Keyword [en]
respiratory measurement, machine testing, oxygen consumption
National Category
Medical Engineering
URN: urn:nbn:se:kth:diva-156103DOI: 10.3357/ASEM.4047.2014ISI: 000343642500012ScopusID: 2-s2.0-84910068714OAI: diva2:778234

QC 20150109

Available from: 2015-01-09 Created: 2014-11-21 Last updated: 2015-09-03Bibliographically approved
In thesis
1. Oxygen content in semi-closed rebreathing apparatuses for underwater use: Measurements and modeling
Open this publication in new window or tab >>Oxygen content in semi-closed rebreathing apparatuses for underwater use: Measurements and modeling
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The present series of unmanned hyperbaric tests were conducted in order to investigate the oxygen fraction variability in semi-closed underwater rebreathing apparatuses. The tested rebreathers were RB80 (Halcyon dive systems, High springs, FL, USA), IS-Mix (Interspiro AB, Stockholm, Sweden), CRABE (Aqua Lung, Carros Cedex, France), and Viper+ (Cobham plc, Davenport, IA, USA). The tests were conducted using a catalytically based propene combusting metabolic simulator. The metabolic simulator connected to a breathing simulator, both placed inside a hyperbaric pressure chamber, was first tested to demonstrate its usefulness to simulate human respiration in a hyperbaric situation. Following this the metabolic simulator was shown to be a useful tool in accident investigations as well as to assess the impact of different engineering designs and physiological variables on the oxygen content in the gas delivered to the diver by the rebreathing apparatuses. A multi-compartment model of the oxygen fractions was developed and compared to the previously published single-compartment models. The root mean squared error (RMSE) of the multi-compartment model was smaller than the RMSE for the single-compartment model, showing its usefulness to estimate the impact of different designs and physiological variables on the inspired oxygen fraction.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. x, 48 p.
TRITA-STH : report, ISSN 1653-3836 ; 2015:6
Diving, rebreather, underwater breathing apparatus, unmanned testing, hyperbaric, metabolic simulator, scuba, semi-closed
National Category
Other Medical Engineering
Research subject
Medical Technology
urn:nbn:se:kth:diva-172949 (URN)978-917595-616-9 (ISBN)
Public defence
2015-09-25, D2, Lindstedtsvägen 5, KTH, Stockholm, 09:00 (English)

QC 20150903

Available from: 2015-09-03 Created: 2015-09-02 Last updated: 2015-09-03Bibliographically approved

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Frånberg, OskarGennser, Mikael
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