| 1. |
- Hjelte, Carl, et al.
(författare)
-
Risk assessment of SWEN21 a suggested new dive table for the Swedish armed forces : bubble grades by ultrasonography
- 2023
-
Ingår i: Diving and Hyperbaric Medicine. - : South Pacific Underwater Medicine Society and the European Underwater and Baromedical Society. - 1833-3516. ; 53:4, s. 299-305
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: To develop the diving capacity in the Swedish armed forces the current air decompression tables are under revision. A new decompression table named SWEN21 has been created to have a projected risk level of 1% for decompression sickness (DCS) at the no stop limits. The aim of this study was to evaluate the safety of SWEN21 through the measurement of venous gas emboli (VGE) in a dive series. Methods: A total 154 dives were conducted by 47 divers in a hyperbaric wet chamber. As a proxy for DCS risk serial VGE measurements by echocardiography were conducted and graded according to the Eftedal-Brubakk scale. Measurements were done every 15 minutes for approximately 2 hours after each dive. Peak VGE grades for the different dive profiles were used in a Bayesian approach correlating VGE grade and risk of DCS. Symptoms of DCS were continually monitored. Results: The median (interquartile range) peak VGE grade after limb flexion for a majority of the time-depth combinations, and of SWEN21 as a whole, was 3 (3-4) with the exception of two decompression profiles which resulted in a grade of 3.5 (3-4) and 4 (4-4) respectively. The estimated risk of DCS in the Bayesian model varied between 4.7-11.1%. Three dives (2%) resulted in DCS. All symptoms resolved with hyperbaric oxygen treatment. Conclusions: This evaluation of the SWEN21 decompression table, using bubble formation measured with echocardiography, suggests that the risk of DCS may be higher than the projected 1%. Copyright: This article is the copyright of the authors who grant Diving and Hyperbaric Medicine a non-exclusive licence to publish the article in electronic and other forms.
|
|
| 2. |
|
|
| 3. |
- Frånberg, Oskar, et al.
(författare)
-
A Metabolic Simulator for Unmanned Testing of Breathing Apparatuses in Hyperbaric Conditions
- 2014
-
Ingår i: Aviation, Space and Environmental Medicine. - 0095-6562 .- 1943-4448. ; 85:11, s. 1139-1144
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 4. |
- Frånberg, Oskar
(författare)
-
Anordning och förfarande för att producera oxygen : Device and method for producing oxygen
- 2005
-
Patent (populärvet., debatt m.m.)abstract
- The invention relates to a medical device for producing oxygen, wherein the device comprises means for providing first conditions, and means for changing said first conditions to second conditions, the device being configured to during a charging phase extract oxygen from air by, under said first conditions, bringing said air (A) into contact with an agent (SfF) constituted by a reversibly oxygen-fixating agent, i.e. an oxygen selective material, such that the oxygen of the air is adsorbed by said agent, and to remove nitrogen under said first conditions, and configured to during a discharging phase release the oxygen from the agent by means of changing said first conditions to said second conditions. The invention also relates to a method for producing oxygen for individual medical purposes.
|
|
| 5. |
- Frånberg, Oskar
(författare)
-
Breathing apparatus
- 1999
-
Patent (populärvet., debatt m.m.)abstract
- A breathing apparatus is described, having a breathing circuit comprising a mouthpiece (8) and one or more gas carrying conduits (60), a compressed gas source (2) and a counterlung (5). The compressed gas source (2) is in communication with the counterlung (5) via the breathing circuit. The counterlung (5) has an expansion assisting means (3) and a contraction assisting means (20), and a control allows selective activation of the expansion assisting means (3) and the contraction assisting means (20). The counterlung has primary (12) and secondary (10) chambers, and inflation of the secondary chamber (10) causes inflation of the primary chamber (12). The expansion assisting means (3) is a flow of compressed gas to inflate the secondary chamber (10).
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Frånberg, Oskar, et al.
(författare)
-
Investigation of a demand-controlled rebreather in connection with a diving accident
- 2011
-
Ingår i: Undersea & Hyperbaric Medicine. - 1066-2936. ; 38:1, s. 61-72
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 9. |
|
|
| 10. |
- Frånberg, Oskar, 1976-, et al.
(författare)
-
Measurement and modeling of oxygen content in a demand mass ratio injection rebreather
- 2015
-
Ingår i: Undersea & Hyperbaric Medicine. - : Undersea and Hyperbaric Medical Society. - 1066-2936. ; 42:6, s. 573-592
-
Tidskriftsartikel (refereegranskat)abstract
- Mechanical semi-closed rebreathers do not need oxygen sensors for their functions, thereby reducing the complexity of the system. However, testing and modeling are necessary in order to determine operational limits as well as the decompression obligation and to avoid hyperoxia and hypoxia. Two models for predicting the oxygen fraction in a demand constant mass ratio injection (DCMRI) rebreather for underwater use were compiled and compared. The model validity was tested with an IS-MIX, Interspiro AB rebreather using a metabolic simulator connected to a breathing machine inside a water-filled pressure chamber. The testing schedule ranged from 0.5-liter (L) to 3-liter tidal volumes, breathing frequencies from five to 25 breaths/minute and oxygen consumptions from 0.5 L/minute to 4 L/minute. Tests were carried out at surface and pressure profiles ranging to 920 kPa(a) (81 meters of sea water, 266 feet of sea water). The root mean squared error (RMSE) of the single-compartment model was 2.4 percent-units of oxygen for the surface test with the 30% dosage setting but was otherwise below 1% unit. For the multicompartment model the RMSE was below 1% unit of oxygen for all tests. It is believed that these models will aid divers in operational settings and may constitute a helpful tool when developing semi-closed rebreathing apparatuses.
|
|
