Diving decompression models and bubble metrics: Modern computer syntheses

Pre-dive Whole-Body Vibration Better Reduces Decompression-Induced Vascular Gas Emboli than Oxygenation or a Combination of Both

“…However, all models can only partly describe reality and are by essence incomplete; they merely serve to “organize our ignorance” of the phenomenon. Therefore, the past 15 years or so, have witnessed changes and additions to diving protocols and table procedures, such as shorter nonstop time limits, slower ascent rates, shallow safety stops, ascending repetitive profiles, deep decompression stops, helium-based breathing mixtures, permissible reverse profiles, multilevel techniques, both faster, and slower controlling repetitive tissue halftimes, smaller critical tensions, longer flying-after-diving surface intervals, and others (Wienke, 2009). Nonetheless, VGE are still known to form in the body after many dives, even those done well within the limits of the accepted decompression model.…”

Theoretical tissue compartment inert gas pressures during a deep dive with and without deep decompression stops: a case analysis

“…Recreational diving beyond traditional "no stop" time and depth limits (recreational technical diving), has undergone explosive growth in recent years [1,2]. Empirically-derived "Haldanean" decompression models such as those developed by Bühlmann are being replaced in personal dive computers and in desktop decompression planning software by a new generation of "bubble models" [3]. To our knowledge, the algorithms these models use have not been validated either with human trials or probabilistically through fitting to existing human trials data.…”

Understanding Dive Computers

“…Able to process depth-time readings in fractions of a second, modern dive computers routinely estimate hypothetical dissolved gas loadings, bubble buildup, ascent and descent rates, diver ceilings, time remaining, decompression profiles, oxygen toxicity, and many related variables. Estimates of these parameters made on the fly rely on two basic approaches [3], namely, the classical dissolved gas model (DGM) and the modern bubble phase model (BPM). Both have seen meaningful correlations with real diving data over limited ranges but differ in staging regimens.…”

“…In applications, the critical phase volume, Φ, is taken near 600 microns 3 and surface tension, γ, is taken around 20 dyne/cm. Diffusivity times solubility, DS, is also fitted to diving data.…”

“…Modern digital dive computers [1][2][3][4][5] date to the early 80s, though analog devices simulating tissue gas uptake and elimination through porous membranes date back to the 70s. Analog devices were limited to nonstop diving and had a short shelf life.…”