[Shearwater Blog] Why UPTD calculations should not be used

[MadUKDiver]

Thought provoking article on the recent Shearwater Blog by Barbara Shykoff (NEDU)

The UPTD model that showed promise in 1970 has been displaced by later evidence. It is time for the diving community to pay attention to the last 40 years of evidence. UPTDs are not a useful measure.

Of course most divers do not have to worry about UPTD (or OTU) but when doing repetitive long multi-dive and multi-day deep diving on CCR it becomes much more relevant.

The Shearwater article does not propose any alternatives but a quick search of this useful list of NEDU milestones shows Barbara’s research at NEDU was published in 2015 in a paper titled “Residual oxygen time model for oxygen partial pressure near 130 kPa (1.3 atm)”.

The paper gives "A two-part residual oxygen time model predicts the probability of detectible pulmonary oxygen toxicity P(P[O2tox]) after dives with oxygen partial pressure (PO2) approximately 130 kPa, and provides a tool to plan dive series with selected risk of P[O2tox]."

Does anyone know if this model has been incorporated into any dive planning software or dive computer firmware?

[gobfish1]

to me
its just more number,s

on dives time and ppo2 that dont fit what we do ,

made me laugh the first link , so you take a pot ride and your vc will take 1 to 3 days to recover lol,
like ill be back in the sea next day ,

run your own numbers for 4 and 6h dives on ppo2 of 1.3 or 1.4 , half lifes are still in the ball park , i say ball park cos that all we have on matter what Flavor we pick ,

if thay can tell me when im going to tox then im all ears , if all thay can tell me is im going to have a sore chest after iv sucked up 9500l of o2 over time, then thats old news

cant see it going on a computer firmware,
what you going to do when it says vc is low take the day off,
and your not even wheezing yet lol.

snip for the other link

It cannot be used
to determine recovery time between hyperbaric oxygen
treatments, or for dives with oxygen-accelerated de-
compression or other exposures to higher PO2

ill stick with repex for tho mo,