Change search
ReferencesLink to record
Permanent link

Direct link
Investigation of a demand-controlled rebreather in connection with a diving accident
KTH, School of Technology and Health (STH), Environmental Physiology.
2011 (English)In: Undersea & Hyperbaric Medicine, ISSN 1066-2936, Vol. 38, no 1, 61-72 p.Article in journal (Refereed) Published
Abstract [en]

This paper describes the examination of a Halcyon RB80 semi-closed underwater breathing apparatus used in a diving accident in 2007. The apparatus was supplied with trimix (oxygen, nitrogen and helium) containing 31% oxygen. The duration of the dive was 105 minutes at 28 meters' average depth in fresh water, with a 19-minute oxygen decompression stop at 6 meters. Upon surfacing the diver experienced seizures and signs of severe neurological deficits. The apparatus was tested with regard to the oxygen fraction drop from the supply gas to the breathing loop - i.e., the oxygen fraction inhaled by the diver (FiO2) was investigated. The FiO2 was measured and found to be lower than the value stated on the manufacturer's web page at the time of the accident. This investigation suggests that during the dive, the actual FiO2% was 17.9-25.3%, which is considerably lower than the FiO2% used for decompression calculations (30%). The underestimation of FiO2 resulted in too short and/or too few decompression stops during ascent. The low FiO2 would also put a diver at risk of hypoxia at shallow depths. It is concluded that inadequate information on the performance of the rebreather was a major contributing factor to this accident.

Place, publisher, year, edition, pages
2011. Vol. 38, no 1, 61-72 p.
National Category
Medical and Health Sciences
URN: urn:nbn:se:kth:diva-31589ISI: 000287180200008PubMedID: 21384764ScopusID: 2-s2.0-79953035179OAI: diva2:406426
QC 20110325Available from: 2011-03-25 Created: 2011-03-21 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

Open Access in DiVA

No full text


Search in DiVA

By author/editor
Frånberg, Oskar
By organisation
Environmental Physiology
In the same journal
Undersea & Hyperbaric Medicine
Medical and Health Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 60 hits
ReferencesLink to record
Permanent link

Direct link