Omitted Decompression

[wazza]

A question:
If we had an Omitted Decompression, what can we do?
And how many ways we have to redo the Decompression.
And can we do it in water or that is it to the Chamber???
Do we keep the diver on O2 after he finishes the Omitted deco,
or do we have to take him 2 the chamber, or do we have other options ??????????????
Thanks in advanced for the help

 

[Dr Deco]

Dear wazza:

Decompression In General

This is really a question of how much decompression time was omitted. Decompression sickness is a function of the “dose” of nitrogen that you receive. Up to a point, nothing will happen when you decompress. What that point is will vary from person to person, and, to some extend, on a daily basis in any given individual.

The “No-Decompression Limits” (NDL) is the name applied to the depth/time curve. It is not really a limit in the sense that it defines a “bends/no bends” limit. There is no question that every diver could have developed for them an NDL that was specific to their physiology. This curve would be far different from the NDL that appears on a dive table. There is safety margin built into the dive tables. We are not “threading the needle” or “going through a keyhole” in any case in recreational diving. How much of a safety margin an individual has is not know, but suffice it to say, you are never on the “fine edge.”

Omitted Decompression

If we are thus speaking about a few minutes of omitted decompression, almost assuredly, there will not be any observable effect. If you had a Doppler ultrasound bubble detector on the diver, you would probably find more vascular bubbles compared to a dive that included the decompression time. The more decompression that is omitted (say, by increasing the bottom time at a given depth), the more Doppler bubbles would be found and eventually DCS would manifest itself. This can be a study performed in a diving laboratory, but definitely you would not want to do this in the field.

Now What

If the omitted time is but several minutes, one should simply watch the diver on the boat. One should never engage in any type of strenuous exercise (run around, climb ladders, etc) since this could provoke the formation of tissue microbubbles. It would be best to end the diving for that day for that person.

If the omission were larger, surface oxygen would be a very good idea. I would not really recommend reentering the water for decompression. That is probably not necessary. Clearly if any signs (what others see) or symptoms (what the diver feels) appear, then it is back to a shore.

Serious Omissions

As described in The Last Dive , a serious omission of tens of minutes can be fatal. These two divers would probably need reentry and a completion of in water decompression of some type. Unfortunately, they were very ill upon surfacing.:boom:

Since all divers are variable, no single rule can apply.

Dr Deco :doctor:

 

[wazza]

Thank u Dr Deco for your answer,
But I will try to rephrase my question
Maybe I will get a better answer or
Or get what I need to know.
Lets say I had to surface for one minutes
And then I need to go back to the water
Or I had to surface for 5 minutes and I need
To go back to the water, what should I do then
Stay on the boat or go to the water and finish
What I started or do I have to do something
Extra and what should be
Thanks again for your help.

 

[Dr Deco]

Dear wazza:

Surfacing During A Dive

If I understand correctly, I believe that you are asking what to do if you surface during a dive? Say a dive is planned to 60 fsw for a total of 60 minutes (US Navy table). During the sixty minutes, you surface, possibly to look for someone or to get a piece of equipment from the surface. You then descend again and complete the sixty minutes. There is not any decompression obligation if the dive was a total of 60 minutes.

If you subtract the time to ascend and while on the surface, that is simply what a decompression computer would do. There is also not any additional decompression obligation. There are some commercial divers who perform dives such as this and they do not have any problems.

Did I understand the question?

Dr Deco :doctor:

 

[wazza]

Ok lets say I was at 55meters for 25 minutes and I had deco for lets say 30 minutes this only an example the numbers aren’t 100 % right, and in the middle of the deco lets say I was between 15meter to 6meter and I had to surface between one minute to five minutes what should I do, continue my plan as it is, or I have to do something else maybe make more deco or I don’t ????
This is what is called the Omitted Decompression
I hope u understood me this time and sorry for my English as every one knows now its not my first language . but thanks for the help big time

 

[Dr Deco]

Dear wazza:

Omitted Deco

I see what you have in mind. This is not really a good idea – as you might guess.

When divers complete the decompression on the surface, they always breathe oxygen for a period of time in the water, then rise to the surface, get placed in a deck decompression chamber (DDC), and complete the depress in the DDC. You wish to do this in the water.

I believe that there might be some information in the US Navy Diving manual concerning the addition of stop time when you reenter the water – if this is ever done at all. Coming t the surface after a deep dive is not really a very good plan.

Yes, you should definitely complete the depress in the water. Do not sit it out on the boat. Some additional time at the stops might be in order.

Dr Deco :doctor: