Driving to Elevation after diving question

[boulderjohn]

If you want further assurance, check out this thread in this thread in the Rocky Mountain regional forum. You will see much more specific information about ascending to altitude there, because EVERYONE leaving the most popular dive site in ANY direction has to ascend more than you are planning to ascend. The thread has very specific information you should be able to apply to your own situation. You will see that every week of the year, people leaving this dive site and heading for Denver will ascend more than 2,000 feet very quickly, and they will ascend more than 3,000 feet on that trip.

 

[geoff w]

I asked a similar question after doing a couple of deep shore dives. See Driving in hills after diving? Our local hills are about 2,500-3,000 feet, and waited about 3 hours before driving. When we're diving in Maui in the morning, we won't go above 2,500 feet elevation for dinner that evening, and that's for a two tank boat dive with the first dive typically to 80-120 feet

When I do a local shore dive down to at most about 40 feet, usually an hour or a bit longer, I don't give much thought to driving in the hills near me afterwards. In general, it's best to err on the side of caution

 

[Searcaigh]

When I lived in Jeddah in Saudi Arabia I used to meet divers who were based up in Taif, who visited Jeddah at weekends doing multiple dives and then driving back up to Taif 1,879m (6,165 ft).

I don't recall anyone mentioning cases of DCS, so perhaps a reasonable SI of several hours and ascending slowly by car is sufficient to avoid it?

 

[boulderjohn]

I don't recall anyone mentioning cases of DCS, so perhaps a reasonable SI of several hours and ascending slowly by car is sufficient to avoid it?

That seems reasonable to me, but there really is no research on it that I know of.

A number of years ago I did some dives on the big island of Hawai'i, finishing in the afternoon, and happened to mention plans to drive to the other side to see the volcano the next morning. One of the dive shop employees advised emphatically against it because of the elevation gain. I looked at the route and saw that I would make a perfectly acceptable minor ascent and then drive for quite some time at that elevation. Then I would make another ascent and drive at the new elevation. That sure looked to me as if I were doing some very long decompression stops, and I went without having any concerns. I still think that makes sense, but I can't point to any research that supports it.

The same thing can happen in reverse. I have on a couple of occasions dived in mountain lakes at more than 10,000 feet elevation. According to altitude diving theory, if you are using the PADI tables, you go up two pressure groups for every 1,000 feet of elevation, so in every case I supposedly arrived at that elevation as a PADI R diver. But the reality is that I started at over 5,000 feet, so I should only be a J diver. But the reality is that I ascended very quickly on a mountain road and was driving at greater than 7,000 feet for quite some time. So if I became a D diver by going to 7,000 feet and then drove for 2 a hour surface interval, doesn't that make me an A diver? If I then ascent to 9,000 feet, am I an E diver? If it takes me an hour to get to the site before the final climb to 10,000+ feet, am I then once again an A diver? Does that final climb to 10,000 feet make me a C diver? If it takes me 1:15 to set up my gear, am I now an A diver again? So which pressure group am I in to start the dive--R, J, A, or something else?

 

[drbill]

We had an instructor here on Catalina that did several shallow training dives with her students, then drove to the other end of the island reaching a maximum elevation of just over 1,600 ft. She got bent and quit diving. That is only one data point of course.

 

[boulderjohn]

We had an instructor here on Catalina that did several shallow training dives with her students, then drove to the other end of the island reaching a maximum elevation of just over 1,600 ft. She got bent and quit diving. That is only one data point of course.

And, of course, you don't know if she got bent because of the drive or if she was bent from the dive, and it just took a little while to manifest itself. I have seen some very knowledgeable people argue that people who get bent after flying soon after diving would have gotten bent if they had not flown. We have no way of knowing.

Both DAN and NOAA say a 2,000 ascent immediately after diving is acceptable.

 

[drbill]

And, of course, you don't know if she got bent because of the drive or if she was bent from the dive, and it just took a little while to manifest itself. I have seen some very knowledgeable people argue that people who get bent after flying soon after diving would have gotten bent if they had not flown. We have no way of knowing.

Both DAN and NOAA say a 2,000 ascent immediately after diving is acceptable.

True. But her dives were all training dives to a max depth of about 40 ft

 

[pasley]

Short version of a longer personal story; Drive to 1,400 feet and two rides in the chamber. Caution is always recommended regarding increase in altitude following a dive. Enjoying at least 2 hours after a dive before leaving the sea shore would always be prudent. A stay at sea level for the night in a local hotel would not be a bad thing.

USN did develop guidelines for driving to altitude following diving complete with Pressure groups, Surface Interval and altitude for drive. In 1999 they changed the table to 1,000 feet.

 

[boulderjohn]

True. But her dives were all training dives to a max depth of about 40 ft

Then I would call her situation inexplicable. It makes no sense to me whatsoever. One possible explanation is that she did not actually have DCS.

A couple of years ago we had a thread that related to DAN and its coverage of chamber treatments. In the thread, a number of internal documents were published. In one of them, DAN was arguing with a treatment center about the importance of having a fully trained hyperbaric physician on staff. DAN said that DCS can be very hard to diagnose. In a lot of cases the patient that was treated did not have DCS. (IIRC, it was nearly half.)The patient had DCS-like symptoms that would have gone away with the passage of time, with or without treatment.

We use the term DCI (Decompression Illness) to cover both DCS and lung overexpansion because the symptoms of the two unrelated problems have extremely similar symptoms and identical treatments. Training dives of 40 feet or less have a very real risk of lung overexpansion injury because of the large number of ascents involved. These dives usually include CESAs, and there is a real risk that an instructor doing multiple CESAs will suffer some kind of lung injury. I remember one time doing a CESA and realizing that I was focusing so hard on making sure the student was exhaling the whole way up that I was not exhaling myself. I had a real "What am I doing???" moment of fear.

The aforementioned DAN argument included spinal stenosis as an example of a condition that can lead to faulty diagnoses. After a time of lugging gear and carrying a scuba setup on the back, spinal stenosis can cause the tingling numbness associated with DCS. The diver will recover after a period of rest. If part of that period of rest was spent in a recompression chamber, the assumption will be that the recompression chamber rather than simple rest caused the recovery.

For a long time I suffered from DCS symptoms after weekends of decompression diving. At first it was minor, but it got worse and worse over several years. The symptoms would begin while I was driving home from New Mexico, a drive that took me over a mountain pass. My hands would go numb on the steering wheel. It would go away, though, so I decided it was not DCS. Over a number of years, the symptoms kept getting worse and worse. Eventually the numbness spread to my arms and made it difficult to sleep at night. It would be bad immediately after diving and then get better day by day. The symptoms subsided in time exactly as they would if I were getting chamber treatments. I went to several doctors before I got an accurate diagnosis--it was carpal tunnel syndrome. My diving weekend included hauling a lot of tanks, and that was the problem. After carpal tunnel surgery, I was completely cured. I have not had those symptoms in years.

 

[drbill]

It is my understanding that the Chamber here at the USC Marine Science Center diagnosed it as DCS. It is my understanding that they have a trained hyperbaric physician on site when a diver is admitted. Fortunately in my 47 years of diving here on Catalina, I've never had to get treated.