Driving to altitude after diving...

[BigJetDriver]

JC Placson: "How many hours is considered safe? I did my first mild deco dive today (100' - 28 min, 1 min stop at 20' on 50%EAN, then a 3 min stop at 15' still on 50%EAN) and had a 5 hour SIT before driving home. The drive home goes over a mountain about 1800'."

If you will look in NOAA's Dive Manual, you will find the table that seems to be the easiest to use, and most sensible at the moment. You can balance that with the experience of those around you, and your own judgement.

We all have to remeber that the tables (any and all of them) are built on averages. At any given time, any one of us can fall outside of the "box"!

You are "somewhat" better off in a car, due to the slower rate of change. It is, however, still a situation of: (1) How much tissue loading exists, and (2) what is the total pressure difference? Remember, it is always a time versus dosage equation.

Current tables and models for wet computers are based on 8000 ft msl as a "cabin altitude" for passenger aircraft. Modern jet aircraft will generally be holding a somewhat lower cabin altitude, in the range of 6000 to 7000 ft msl, due to better pressurization systems, but you wouldn't want to bet the bank on that.

BJD

 

[mempilot]

Do a search on this. I believe DAN (don't quote me here) considers the effects of driving to altitude similar to flying after diving. Of course in flying your ascent is much more rapid and you are pressurized in a commercial airliner to about 8-10K ft. Driving would have a much slower rise in altitude rate. It might be best to look at it in a similar context. I use to live in B.C. and would drive home up the mountainside after a dive trip but that trip would take 1-2 hours and I never had any problems.

The airliner I fly maintains a maximum cabin pressure altitude of 8000' at it's maximum operating altitude of 35000'. The pressurization controller in auto mode keeps the climb at a steady 350' per minute while the aircraft is climbing at 1500' or better per minute. The maximum cabin pressure altitude you'll ever see in an aircraft when the pressurization system is normal is 10,000'. Above 10k, the effects of hypoxia really start to show up. The higher the jet is certified to, the larger the pressure differential has to be to maintain an operational cabin pressure of under 10k ft.

I flunked math, but depending on the gradient of the road traveled up the mountain and the speed you drive, you should be able to figure out your vertical speed in a car. You can then compare this to the airplane model and see if you're exceeding it. I doubt it. Just don't do a Pike's Peak hill climb in your Audi racecar after diving though.

 

[Dr Deco]

Hello Scuba Board Readers:

Many thanks for all of the replies to driving over a mountain after diving.

As I have mentioned before, tables such as those in the NOAA book have not been tested with the subjects performing heavy exercise or work following a dive. If you have walked a distance and lugged equipment, you should bear in mind that you may be creating micronuclei and the tables need to have the “surface interval” extended. :sprite10:

Dr Deco :doctor:

 

[sharkmasterbc]

Thank you all for your relpies. I think I will just opt to stay @ sea level until my desat time reaches "0".

 

[pch90265]

Hi,

I am a complete newby diver -- I've done two resort dives, and have just completed my PADI confined water... I'll be completing my Open Water next weekend!!!

As I continue diving this summer, I plan to make several day-trips to Catalina Island and the Channel Islands. I live in Topanga Canyon in the Santa Monica Mountains -- the range that fringes the Santa Monica Bay -- at an altitude of approx 1200'.

Assuming that it's going to be 60-90 minutes minimum from the time I exit the water until the time I get on the ferry or boat; it's going to be 60-90 minutes to get across the channel to my car; and, it's going to be 60-90 min to drive home... That gives me a 3 hour minimum surface interval before the last 15 minutes of my drive from the Pacific Coast Highway to the switch-backs that lead to my house.

Here's my question: will I have a DCS/DCI problem driving to this altitude (a hair over 1000') after a three hour surface interval???

I appreciate your input.
--Sean--

 

[Mako Mark]

Good question. The potential is there. I would be careful and probably invest in a dive computer that tells you when it is safe to ascend to altitude. A lot of people forget about driving to altitude after diving.

 

[fan(t)a(s)tic]

You might want to recheck my math, but from what I calculate it shouldn't pose a problem to go from sea level to 1200ft.

I'm stuck in metric units, but I'll try to explain.

Going from the surface to 33ft down, you'll increase pressure from 1bar to 2bar (33ft equals 1bar).
Going from 0 to 1200ft up, reduces the pressure from 1bar to 0.970bar (in a standard atmosphere, 59°F at sea level and 29.92in pressure), which is equal to just about one foot difference in depth under water.

I know that I go up and down more than one foot while diving "level" and that hasn't ever been a problem for me.

Again: this might not be correct, but I tried to dredge up what I remembered from physics. This is not based on medical knowledge!

If anybody finds a fault in my reasoning: PM me and I'll take this answer off the board!

 

[DocVikingo]

As your inquiry is more a decompression issue than one of diving medicine per se, I have taken the liberty of moving it.

Best regards.

DocVikingo

 

[DepartureDiver]

Hi Sean. Yes it is a concern. It doesn't sound like much of a change but it is. To help with this, you should decrease your maximum no-stop times and dive more conservative ... and the times should be reduced more at the shallower depths. Think of it as a percentage decrease and not a decrease in minutes. Our altitude dives also require a post-dive ascent and we plan our dives to allow for an immediate ascent plus adding in a buffer for the great unknown. To minimize any DCI risk (which you should be doing anyway) you should be making nice slow ascents with nice safety stops including deep safety stops when doing deeper dives. If you have any other questions, just post again and we will all jump back in.

 

[fan(t)a(s)tic]

Hi Brian

Is my math or my thinking off?

I'd appreciate your comment

Steve