| 1. |
- Andersson, Johan, et al.
(författare)
-
Arterial oxygen desaturation during apnea in humans
- 1998
-
Ingår i: Undersea & Hyperbaric Medicine. - 1066-2936. ; 25:1, s. 5-21
-
Tidskriftsartikel (refereegranskat)abstract
- We studied the effect of the human diving response, defined as bradycardia and reduced peripheral blood flow, on arterial hemoglobin desaturation. We induced a diving response of different magnitudes by using apnea in air and apnea with face immersion. Each of 21 subjects performed five apneas in air and five apneas with face immersion in 10 degrees C water. Periods of apnea in both conditions were of the same duration in any individual subject (average: 126.4 s) and the order of air and water was equally distributed among subjects. Heart rate, skin capillary blood flow, arterial blood pressure, arterial hemoglobin oxygen saturation during apneas, and end-tidal fractions of CO2 after apneas were recorded with non-invasive methods. The bradycardia and capillary blood flow reduction during apnea in air (7.8 and 37.7% change from control, respectively) were significantly potentiated by face immersion (13.6 and 55.9%, respectively). Arterial hemoglobin desaturated more during apnea in air (2.7%) compared to during apnea with face immersion (1.4%). We conclude that the potentiation of the human diving response with face immersion in cold water leads to a smaller decrease in arterial hemoglobin saturation, which may reflect an oxygen-conserving effect.
|
|
| 2. |
|
|
| 3. |
- Blogg, S. Lesley, et al.
(författare)
-
Observed decompression sickness and venous bubbles following 18-msw dive profiles using RN Table 11
- 2017
-
Ingår i: Undersea & Hyperbaric Medicine. - : Undersea & Hyperbaric Medical Society. - 1066-2936. ; 44:3, s. 211-219
-
Tidskriftsartikel (refereegranskat)abstract
- The venous bubble load in the body after diving may be used to infer risk of decompression sickness (DCS). Retrospective analysis of post-dive bubbling and DCS was made on seven studies. Each of these investigated interventions, using an 18 meters of sea water (msw) air dive profile from Royal Navy Table 11 (Mod Air Table), equivalent to the Norwegian Air tables. A recent neurological DCS case suggested this table was not safe as thought. Two-hundred and twenty (220) man-dives were completed on this profile. Bubble measurements were made following 219 man-dives, using Doppler or 2D ultrasound measurements made on the Kisman-Masurel and Eftedal-Brubakk scales, respectively. The overall median grade was KM/EB 0.5 and the overall median maximum grade was KM/EB 2. Two cases of transient shoulder discomfort ("niggles") were observed (0.9% (95% CL 0.1% 3.3%)) and were treated with surface oxygen. One dive, for which no bubble measurements were made, resulted in a neurological DCS treated with hyperbaric oxygen. The DCS risk of this profile is below that predicted by models, and comparison of the cumulative incidence of DCS of these data to the large dataset compiled by DCIEM [1, 2], show that the incidence is lower than might be expected.
|
|
| 4. |
- Blogg, S.L., et al.
(författare)
-
The effect of breathing hyperoxic gas during simulated submarine escape on venous gas emboli and decompression illness
- 2003
-
Ingår i: Undersea & Hyperbaric Medicine. - 1066-2936. ; 30:3, s. 163-174
-
Tidskriftsartikel (refereegranskat)abstract
- Raised internal pressure in a distressed submarine rapidly increases the risk of decompression sickness (DCS) following submarine escape. The hypothesis that breathing a hyperoxic gas during escape may reduce the risk of DCS was tested using goats. Shallow air saturation and simulated submarine escape dives were carried out either singularly or in combination (saturation, escape, or saturation followed by escape) using air or 60% / 40% oxygen (O2) / nitrogen (N2) mixture as breathing gas during the escapes. Post-surfacing, animals were observed for signs of DCI and O2 toxicity. Precordial Doppler ultrasound was used to score venous gas emboli (VGE) using the Kisman Masurel (KM) scale. Following escape from 2.5 MPa, the rate at which VGE disappeared in the hyperoxic group (n = 8) was significantly faster(p < 0.05) than the air group (n = 7). One case of pulmonary barotrauma with arterial gas embolism occurred in the air group, but no cases of DCS were observed. After saturation at 0.18 MPa followed by escape from 2.5 MPa, DCS occurred in four of 15 animals in the air group and in two of 16 animals in the hyperoxic group. The rate of disappearance of VGE was significantly faster (p < 0.01) in the hyperoxic group. O2 toxicity was not discernible in any of the animals.
|
|
| 5. |
- 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.
|
|
| 6. |
- 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.
|
|
| 7. |
- Gennser, Mikael, et al.
(författare)
-
Oxygen and carbogen breathing following simulated submarine escape
- 2014
-
Ingår i: Undersea & Hyperbaric Medicine. - 1066-2936. ; 41:5, s. 387-392
-
Tidskriftsartikel (refereegranskat)abstract
- Escape from a disabled submarine exposes escapers to a high risk of decompression sickness (DCS). The initial bubble load is thought to emanate from the fast tissues; it is this load that should be lowered to reduce risk of serious neurological DCS. The breathing of oxygen or carbogen (5% CO2, 95% O-2) post-surfacing was investigated with regard to its ability to reduce the initial bubble load in comparison to air breathing. Thirty-two goats were subject to a dry simulated submarine escape profile to and from 240 meters (2.5 MPa). On surfacing, they breathed air (control), oxygen or carbogen for 30 minutes. Regular Doppler audio bubble grading was carried out, using the Kisman Masurel (KM) scale. One suspected case of DCS was noted. No oxygen toxicity or arterial gas embolism occurred. No significant difference was found between the groups in terms of the median peak KM grade or the period before the KM grade dropped below III. Time to disappearance of bubbles was significantly different between groups; oxygen showed faster bubble resolution than carbogen and air. This reduction in time to bubble resolution may be beneficial in reducing decompression stress, but probably does not affect the risk of fast-tissue DCS.
|
|
| 8. |
- Hagberg, Mats, 1951, et al.
(författare)
-
Incidence and risk factors for symptoms of decompression sickness among male and female dive masters and instructors--a retrospective cohort study.
- 2003
-
Ingår i: Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc. - 1066-2936. ; 30:2, s. 93-102
-
Tidskriftsartikel (refereegranskat)abstract
- The aim was to determine the incidence of symptoms of decompression sickness (DCS) in dive masters and instructors in relation to number of dives and possible risk factors. STUDY DESIGN: Retrospective cohort study of dive masters and instructors in Sweden. STUDY BASE: All dive masters and instructors listed with PADI, NAUI and CMAS in Sweden as of January 1st 1999 (2380 divers). METHODS: The dive masters and instructors received a validated questionnaire on diving activities and symptoms of DCS in 1999. 1516 men and 226 women answered, i.e. 73% of the initial study base. RESULTS: DCS symptoms were reported by 190 divers. The incidence of DCS symptoms was 1.52 for males and 1.27 for females per 1000 dives. Dive masters, divers not performing decompression-stop dives, divers not practicing advanced diving and divers with a low number of total lifetime dives had a higher proportion (p < 0.05) of DCS symptoms per 1000 dives. There were no major differences in DCS symptom incidence related to sex, age, asthma, overweight or alcohol abuse in this study.
|
|
| 9. |
- Larsson, Agneta, et al.
(författare)
-
Nitrox permits direct exit for attendants during extended hyperbaric oxygen treatment
- 2012
-
Ingår i: Undersea & Hyperbaric Medicine. - 1066-2936. ; 39:1, s. 605-612
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Intermittent breathing of oxygen-enriched air, nitrox (1:1 air:oxygen, 60.5%O-2), for attendants in multiplace hyperbaric chambers should enable treatment protocols (HOPAN hyperbaric oxygen protocol attendants' nitrox) of up to 200 minutes at 2.8 atmospheres absolute (ATA), while retaining the option of a direct decompression and exit.Methods: HOPAN with cycles of 15 minutes of nitrox breathing followed by 10 minutes of chamber air for attendants were occasionally used from 2007-2009. HOPAN vs. LTP (local treatment protocols) were evaluated via an anonymous enquiry among attendants; patients' medical records were followed six months post-HBO2 treatment (HBO2T).Results: 88 HOPANs, with 59 chamber attendants assisting 30 patients, were documented. HOPAN duration ranged from 55-167 minutes (median 140 minutes). 31/59 attendants answered the enquiry. Perceived comfort of each protocol (HOPAN vs. LTP) by attendants was reported as equal. Symptoms, both minor (parestesias) and severe (joint pain), were reported in connection with LTP, while only one occurrence (mild joint pain) was reported in connection with HOPAN. No complications were documented among the attendants or the patients. It is suggested that nitrox breathing for chamber attendants provide flexible HBO2T for patients at 2.8 ATA for up to 200 minutes within no-decompression limits, facilitating future studies of HBO2T dosage.
|
|
| 10. |
- Lindholm, Peter, et al.
(författare)
-
Profound hypercapnia but only moderate hypoxia found during underwater rugby play
- 2022
-
Ingår i: Undersea & Hyperbaric Medicine. - : UNDERSEA & HYPERBARIC MEDICAL SOC INC. - 1066-2936. ; 49:3, s. 367-372
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Underwater rugby is a team sport where players try to score points with a negatively buoyant ball while submerged in a swimming pool. Reports of syncope incidents at the Swedish Championships led to us to investigate end-tidal oxygen and carbon dioxide levels during simulated match play. Methods: Eight male underwater rugby club players of varying experience participated. Repetitive measurements were made while players were defending during simulated match play. Each time a player surfaced they exhaled through a mouthpiece connected to a flow meter and a gas analyzer to measure tidal volume, PETO2 and PETCO2. Results: Measurements were made over 12 dives, with an average dive duration of 18.5 seconds. The mean maximal PETCO2 across the eight participants was 10.0 kPa (similar to 75 mmHg) (range, 9.1-11.7 [-68-88]). The corresponding mean minimum PETO2 was 7.6 kPa (similar to 57 mmHg) (6.3-10.4 [similar to 47-78)). PETCO2 drifted upward, with the mean upward change from the first to last dive for each participant being +1.8 (similar to 13.5 mmHg) (SD 1.74) kPa. A similar trend for PETO2 was not detected, with a mean change of similar to 0.1 (similar to 0.75 mmHg) (SD 3.79) kPa. Conclusion: Despite high PETCO2 values that were close to narcotic being recorded, these players seemed to regulate their urge to breathe based on hypoxia rather than hypercapnia.
|
|
