MODERN DECOMPRESSION ALGORITHMS B.R.Wienke
MODERN DECOMPRESSION ALGORITHMS:
MODELS, COMPARISONS, AND STATISTICS
B.R. Wienke
Los Alamos National Laboratory
Applied Physics Division
Los Alamos, N.M. 87545
INTRODUCTION
Overview
The subject of decompression theory in general is the study of pressure changes in blood and tissues. And today,
we still do not know all the answers, maybe even less, the questions. But for diving applications, we need regimens and
protocols to stage diver ascents on any given breathing mixture, and that is the focus of this short paper. Deterministic
models are broadly catergorized as dissolved gas (Haldane) or dual phase (dissolved plus free gas), and both are described
and contrasted. Probabilisticmodels fold risk parameters over statistical data inmaxinum likelihood, employing
metrics and variables computed directly in deterministic models. The statistics associated with decompression illness
(DCI) are also discussed.
DEEP STOPS AND DEEP HELIUM Bruce R. Wienke and Timothy R. O'Leary
DEEP STOPS AND DEEP HELIUM
RGBM Technical Series 9
Bruce R. Wienke and Timothy R. O’Leary
NAUI Technical Diving Operations
Tampa, Florida 33619
BASICS
Deep stops – what are they?
Actually, just what the name suggests. Deep stops are decompression stops made at deeper depths than those
traditionally dictated by classical (Haldane) dive tables or algorithms. They are fairly recent (last 15 years) protocols,
suggested by modern decompression theory, but backed up by extensive diver practicum with success in the mixed gas
and decompression arenas - so called technical diving. Tech diving encompasses scientific, military, commercial, and
exploration underwater activities. The impact of deep stops has been a revolution in diving circles. So have slower
ascent rates across recreational and technical diving. In quantifiable terms, slower ascent rates are very much akin to
deep stops, though not as pronounced as decompression stops. Deep stops plus slow ascent rates work together. And
they work together safely and efficiently.
Understanding M-values By Erik C. Baker, P.E
Understanding M-values
By Erik C. Baker, P.E.
In conjunction with an array of hypothetical "tissue" compartments, gas
loading calculations and M-values compose the major elements of the
dissolved gas or "Haldanian" decompression model. Through the use of
widely-available desktop computer programs, technical divers rely on this
model for their decompression safety. A good understanding of M-values
can help divers to determine appropriate conservatism factors and evaluate
the adequacy of various decompression profiles for a particular dive.
Deep Stops By Erik C. Baker, P.E
Clearing Up The Confusion
About “Deep Stops”
By Erik C. Baker, P.E.
The old adage, “an ounce of prevention is worth a pound of cure,” is certainly applicable to the
various symptoms of decompression sickness (DCS). The best treatment of all for these maladies
is to complete a sufficient decompression profile in the first place. Technical divers have
observed that many ailments can be avoided by including “deep stops” in their profiles. A closer
examination of the decompression model reveals that this practice serves to reduce or eliminate
excessive overpressure gradients. Knowing this, the model can be modified to provide precise
control of gradients and stops can be calculated within the decompression zone to the depth of the
“deepest possible decompression stop.”
Comparison of V-Planner VPM-B to GAP RGBM and GF Deco Tables
Ascents from 200 ft (61m)
Dives on Trimix 18/45
Comparison of V-Planner VPM-B
to GAP RGBM and GF Deco Tables
•This compilation demonstrates that VPM-B is linearly correlated to
RGBM, and is dissimilar to GF decompression for an array of dive profiles.
•Analytical dive planning is also discussed, with consideration of lost gas
scenarios, rules for VPM-B deco-on-the-fly, and gas consumption vs.
bottom times and deco gas sets.
Gas Exchange Partial Pressure Gradients and the Oxygen Window
Johnny E. Brian, Jr., M.D.
Associate Professor
Department of Anesthesia
University of Iowa College of Medicene
The oxygen window. Inherent unsaturation.Partial pressure vacancy. Most divers with an
interest in decompression diving have likely encountered one of these termes at some
time. All three terms are used to describe the same physical phenomenon.