On the theoretical evaluation of one yo-yo diving profile on air for fish-farming

Abstract

On the theoretical evaluation of one yo-yo diving profile on air
for fish-farming

Abstract:
A yo-yo diving profile is one with very rapid and repeated depth changes. Due to the speed of depth changes in excess of 20 m/min and the quickly repeated ascents and descents within 1 to 5 min, a standard decompression model based on perfusion or a dive computer or a logging device can no longer track the changes in the inertgasload in the diver’s body properly.

One form of ubiquitious yo-yo diving is done in fish-farming, clearly needed to change air-tanks, tools, debris and locations within a multiple array of the
fish-nets.

The already available historic sources ([1], [2], [4], [5] & [6]) address this topic clearly and the connected risks but without hints of complete mitigation.

We propose simple & straightforward modifications of an existing perfusion model [12] to mitigate the risk of decompression sickness and/or arterial/
cerebral air embolism.

Full text

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On the theoretical evaluation of
one yo-yo diving profile on air
for fish-farming
DOI: 10.13140/RG.2.2.: t.b.d.!

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Abstract:
A yo-yo diving profile is one with very rapid and repeated depth changes.
Due to the speed of depth changes in excess of 20 m/min and the quickly
repeated ascents and descents within 1 to 5 min, a standard
decompression model based on perfusion or a dive computer or a logging
device can no longer track the changes in the inertgasload in the diver’s
body properly.
One form of ubiquitious yo-yo diving is done in fish-farming, clearly needed
to change air-tanks, tools, debris and locations within a multiple array of the
fish-nets.
The already available historic sources ([1], [2], [4], [5] & [6]) address this
topic clearly and the connected risks but without hints of complete
mitigation.
We propose simple & straightforward modifications of an existing perfusion
model [12] to mitigate the risk of decompression sickness and/or arterial/
cerebral air embolism.

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Methods (1):
The yo-yo profile in question is the one from: [5], p. 24:

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Methods (2):
A quick check with available desktop deco software programs (pls. cf. the
„Bonus Material“ at the end of this presentation and [3]) confirmed
the findings from [1], [4], [5] & [6];
the calculated
inertgas loads
do not suggest
any decompression
or safety stop:
(the used color
scheme for the
heat maps was
proposed by DAN
within the
DSL framework)

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Methods (3):
To keep track on the inertgas loads in the various theoretical tissue-
compartments during the rapid pressure changes due to fast ascents and
descents, compartments with very small half-times (HT), i.e.
high perfusion rates, have to be introduced.
Since 6 halftimes are needed to saturate (or desaturate) these theoretical
compartments, haltimes in the minute resp. sub-5-minute ranges are clearly
required, so one compartment with a halftime of ca. 70 secs and a 2 min
compartment are added on the fast side of the halftime-spectrum from [12];
and one intermediate compartment with a HT of ca. 9 min is added as well
([7]).
These new fast compartments are pretty well in-line with the data,
extracted from Paulev [9], [10] & [11] resp. [8] on p.19.

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Methods (4):
With [7], p. 6 and the aid of [12], p. 129:
where, in the a-coefficient, the 3rd. root of the half-time τ is, according to
Buehlmann, an indicator to the excess volume of inertgas and thus could
be mapped onto the simulated bubble volumes of [7].

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Methods (5):
Source: [7], p. 5:
[7], p. 6:

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Methods (6):
The new compartments were tailored to the a-/b coefficient scheme of the
ZH-L 16 framework [12] with a clear stress to fast compartments to keep
track of the expedited change in inertgas loads. The yellow display are the
new and overpressure-
sensitive fast compartments.
Compartment #2 with
2 min halftime (TAU) is
calculated according to the
rule from [12], p. 129, but was
never used by Buehlmann.
The rest of the compartments
are original Buehlmann et.al.,
the gradient factors High &
Low equal to 1.0, i.e.: 100 %.

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Methods (7):
Since Haldane [13], p. 346 the abundance of inertgas (micro-)bubbles is
associated with delayed de-saturation, i.e. prolonged half-times. This is as
well addressed, for example, in the EL-algorithm used for the new USN air
diving tables ([14]).
Here, we use a compartment matrix with increased halftimes of 50 % in the
first 8 compartments only for
the 5 ascents of this
yo-yo profile:

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Results (1):
By using these modified ZH-L coefficients matrices
(pls. cf. slide #8 for descent, slide #9 for ascent) already during the first
ascent a decompression / safety stop of ca. 1 min is suggested:
This even more so after the
consecutive 4 descents/ascents:

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Results (2):
During the consecutive ascents the ceiling / safe ascent depth
increases from ca. 2.35 m to 2.45 and the stop times accumulate from
1 min to ca. 4 min: after the complete series of 5 bottom times and 5 ascent
spikes, our modified model suggests a
decompression stop > 4 min at a stop depth of ca. 4 +/-2 m.
However:
an even higher benefit
in terms of reduced
inertgas load could be
achieved by changing
the breathed gas to
100 % oxygen at
approx. 6 m
during the last,
the 5th. ascent
and a final stop:

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Discussion:
The extreme form of repetitive diving like the yo-yo profiles
used for professional fish-farming can not be adequately
adressed neither by standard perfusion models like the ZH-L16 or a Workman
algorithm ([2], [5], [6]) nor by standard diffusion models ([1], [4]) since the used
compartment half-times resp. diffusion coefficients are not fitting to the fast
inertgas absorption / release processes during the spikes of the yo-yo profile.
Instead, fast compartments with half-times in the sub-minute region should be
added.
We extracted fast-compartment data [8] with a half-time of ca. 70 sec
from [9]  [11] which are in-line with a recently developped new model [7].
Thus the tested profile required short and shallow decompression resp.
safety stops already for the first spike of the yo-yo series. After the complete
series of spikes, our model suggest a stop > 4 min @ 4 m +/- 2 m.

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Sources / References (1):
[1] Smart DR, Van den Broek C, Nishi R, Cooper PD, Eastman D.
Field validation of Tasmania’s aquaculture industry bounce-diving
schedules using Doppler analysis of decompression stress. Diving and
Hyperbaric Medicine. 2014 September:44(3):124-136
[2] Bühlmann, A.A. (1987) Decompression after repeated dives, Undersea
Biomed Res. Vol. 14, #1, p. 59 - 67 (3810993)
[3] the SubMarineConsulting Group(1991) DIVE: a decompression suite;
pls. cf. slide #16
[4] Diving methods and decompression sickness incidence of Miskito Indian
underwater harvesters RG DUNFORD, EB MEJIA, GW SALBADOR, WA
GERTH, NB HAMPSON, UHM 2002, Vol. 29, #2, p. 75 -85
(12508972)

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Sources / References (2):
[5] Hahn, Max. H. (1995) Workman-Bühlmann Algorithm for Dive
Computers: a critical analysis; in: Hamilton, R.W. (ed.) The effectiveness of
dive computers in repetitive diving; p. 19 – 25
[6] Hahn, M.H. (1992) Dive Computers – Today and Tomorrow; in: Wendling
/Schmutz (eds.) Safety Limits of Dive Computers, Dive Computer
Workshop, p. 30 – 35
[7] SaulGoldman,J.M.Solano-Altamirano (2015) Decompressionsickness in
breathholddiving and its probable connection to the growth and dissolution
of small arterial gasemboli, Mathematical Biosciences262(2015)1–9;
http://dx.doi.org/10.1016/j.mbs.2015.01.001
[8] Salm, Albrecht (2018) Essay on fast and super-fast compartments;
DOI: 10.13140/RG.2.2.30451.35366
Or there: Tech Diving Mag, Issue 30 / 2018:
On Fast- and Super-fast Compartments, p. 10 -20

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Sources / References (3):
[9] PAULEV, P. Decompression sickness following repeated breathhold dives.
J. Appl. Physiol. 20(5) : 1028-1031. 1965
[10] PAULEV, POUL-ERIK, AND NOE NAERAA. Hypoxia and carbon dioxide
retention following breath-hold diving. J. Appl. Physiol. 22(3) : 436-440. 1967.
[11] PAULEV, POUL-ERIK. Nitrogen tissue tensions following repeated
breath-hold dives. J. Appl. Physiol. 22(4): 714-718. 1967
[12] Bühlmann, Albert A., Völlm, Ernst B. (Mitarbeiter), Nussberger, P. (2002):
Tauchmedizin, 5. Auflage, Springer, ISBN: 3-540-42979-4
[13] Haldane, J S. Respiration, Yale University Press,
1922, 1927
[14] Thalmann ED, Parker EC, Survanshi SS, Weathersby PK. Improved
probabilistic decompression model risk predictions using linear-exponential
kinetics. Undersea Hyper. Med. 1997; 24(4): 255 – 274

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Bonus Material (1):
Source for
DIVE Version 3_09
Download free of charge:
DIVE V 3_09
(https://www.divetable.info/DIVE_V3/index.htm)
 and the german manual
https://www.divetable.info/DIVE_V3/DOXV3_0.pdf
The release train for
the english version (V3_04) is somewhat slower …
DIVE V 3_09 is not compatible with all older versions!
https://www.divetable.info/DIVE_V3/V3e/index.htm

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Bonus Material (2):
3 ASCII (text) files with the data,
for easy reference & download
The nitrogen coeffcients matrix für saturation
(descents & bottom time), slide #8:
https://www.divetable.info/beta/Fishfarm/N2COEFF.TXT
The nitrogen coeffcients matrix für de-saturation
(ascents & decompression / safety stops), slide #9:
https://www.divetable.info/beta/Fishfarm/F10.TXT
The calculated inertgas pressures in the 16 compartments,
after the 5th. spike, that is: the completed yo-yo profile,
prior to ascent, i.e. run-time 46.5 min):
https://www.divetable.info/beta/Fishfarm/Fishfarm.TXT

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Bonus Material (3):
 the heat-map, prior to the last stop, run-time 48 min

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The paradigm dive from above via these commands,
the input of commands and parameters are in the quotes: „ “
„d“ (simulation of one spike of the yo-yo box profile with these
parameters:)
„15.“ (bottom depth)
„8.“ (bottom time)
„a“ (ascent)
the manipulation of the coefficients matrices is done via:
„nc“ (nitrogen coefficients):
with the option 3 the matrices from
slides #8 & 9 could be loaded
into the service engine of the
DIVE software.
The heat maps are generated via:
 „%p“
Handling of DIVE:

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Fine tuning could be done via the commands:
 ascent rate („AR“)
ambient atmospheric pressure at start („L“)
the respiratory coefficient („R“)
the ambient (water)-temperature („te“)
the water density („di“)
Buehlmann Safety Factor („B“)
last stop depth („LS“)
And with: „a“ we recieve the complete decompression prognosis;
i.e.: the stop times in min per stage, modulo 3 m
and the responsible leading compartment & the rounded up TTS in
min. The latest DIVE Version for beta testing is always staged there:
https://www.divetable.info/beta/index.htm
along with information on production date, size in bytes, new features and
the checksums for verifying the download.
Fine tuning of DIVE: