New Method Measures Nitrogen Absorption in Divers, Could Improve Decompression Safety
Researchers have developed a technique to precisely track how divers' bodies absorb and expel nitrogen during submersion, filling a critical data gap in decompression sickness prevention. The breakthrough could enable more accurate risk models for diving operations, potentially reducing injuries and liability for commercial diving companies and military programs.
Originaltitel: Measuring whole-body inert gas uptake and washout during submersion
En rebreather-baserad mätmetod kan för första gången kvantifiera inertgaskinetiken hos dykare under nedsänkning — data som saknats för att förbättra riskmodeller för dekompressionsjuka. Svenska Försvarsmakten och Lund University utvecklade metoden genom att mäta förändrad flytkraft under dykningar. Den återspeglar stickväxling av kväve under konstant syretryck. I studien genomförde två dykare åtta dykningstillfällen på 2,5 bar (botten) respektive 1,3–1,4 bar (dekompressionsfas). Uppmätt kväveupptagning var 0,96 liter under bottenfasen och utsöndring 0,67 liter under dekompression. Med åtta försöken uppnåddes en detektionsprecision (MDD) på 0,28 liter respektive 0,26 liter vid 80 procents statistisk kraft. Resultaten öppnar väg att samla användbar data på gaskinetik kopplat till dekompressionsjukerisker — relevant för både säkerhetsprotokoll inom yrkesdykning och framtida hyperbarmedicinsk klinisk praxis.
Introduction: Quantifying inert gas uptake and washout is critical for understanding decompression sickness (DCS). However, the limited amount of data has made it difficult to integrate inert gas kinetics into risk models for DCS. Measuring whole-body inert gas kinetics during submersion is technically challenging. This study presents a novel method for quantifying inert gas uptake and washout in human divers using a rebreather-based system. Methods: During constant-depth diving with a closed-circuit system that maintains a constant oxygen partial pressure, changes in buoyancy will reflect the kinetics of inert gas. Two divers completed four dives each, with a bottom phase at 2.5 bar and a decompression phase at 1.3 bar or 1.4 bar. Load cell data were converted into equivalent changes in volume of nitrogen standardised for temperature and pressure (VN2, STP). Power analysis was conducted to quantify the resolution by which the method could detect nitrogen uptake and washout volumes. Results: Distinct uptake and washout curves were obtained, comparable to previous studies using other techniques. Mean VN2 uptake during the bottom phase was 0.96 L (SD 0.29), while mean washout during decompression was 0.67 L (SD 0.26). The minimal mean detectable difference (MDD) with eight dives was 0.28 L for the bottom phase and 0.26 L for the decompression phase, considering standard 80% power and a 0.05 significance level. Conclusions: This novel method quantifies inert gas kinetics during submersion with acceptable precision and accuracy. It could facilitate the collection of inert gas kinetics data during submersion, potentially yielding valuable correlations with the risk of DCS.