Earned, Un-earned or Predisposed?

[Divedoggie]

Kent,

When doing days like this (and we do have days like this), our instructors all use Nitrox.

Still, it is a brutal schedule, and I am not sure that dive shops realize how physically demanding it is when they schedule things like this.

Was this at Santa Rosa? Was the pass you were talking about Raton Pass? If so, then the bigger problem is the elevation gain prior to reaching Las Vegas. You will gain a couple thousand feet elevation gain almost immediately out of Santa Rosa, then hold steady for a long time before Raton, crossing which will add surprisingly little to the altitude at which you have been driving for several hours.

Altitude is a real question in dives in this area. In our group it is very controversial, since we are UTD divers, and UTD says that altitude has no effect on DCS and can be disregarded. (I don't agree.) I posted some questions about this in the Ask Dr. Decompression forum after a diver got a bad DCS hit in Santa Rosa, but my question was pretty much ignored by everyone.

I would sure like to have some of the deco heavyweights jump in on this question.

Yes, it was in Santa Rosa.
In the past, we have always done days like this on Nitrox too. If we want to dive Nitrox, we blend our own gas, which takes a lot of time. It seems like we run around anticipating the needs of students and making their safety paramount, but we neglect ourselves. I'm trying to amass information from the incident, from people here on SB, DAN, and other sources. As a result we will hopefully adopt a new shop policy, and at least, I will adopt a new personal policy!

As Instructors, we could have Open water classes with a maximum number of students allowed by standards and make the weekend economically feasible, but lose quality of education and individual student experience.

Small classes allow for individual attention and feeback. Teaching Rescue, Specialties, AOW, and OW during a weekend allows for small classes and makes the trips economically worthwhile. The result of that schedule is a very busy Instructor.

Because of the elevation gain out of Santa Rosa to Las Vegas, Raton Pass, and even Colorado Springs, our friend went to the hyperbaric facility at Poudre Valley Hospital. Its a first rate facility and I assume he was well assessed there.

John, I know a lot of people who dive the way they dive in Santa Rosa because, "thats the way they have always done it and it has worked so far." If you get any info from Deco heavyweights concerning UTD or Rec diving at altitude, I'd love to see the info.

 

[Bubbletrubble]

Altitude is a real question in dives in this area. In our group it is very controversial, since we are UTD divers, and UTD says that altitude has no effect on DCS and can be disregarded. (I don't agree.) I posted some questions about this in the Ask Dr. Decompression forum after a diver got a bad DCS hit in Santa Rosa, but my question was pretty much ignored by everyone.

@boulderjohn: I took a quick look at the old thread you mentioned. You guys were using UTD Ratio Deco to conduct the dive, correct? That's interesting. My understanding is that RD is a "derivative" approach that helps one come up with an ascent profile on-the-fly that closely approximates what some deco algorithms might recommend. Sounds great...but I don't think I'd want to rely on it as my primary dive-planning tool. Since RD is rather new, it would seem prudent to compare profiles with other well-established deco algorithms (with proven, successful track records) and perhaps use RD as a backup method.

I suspect that whoever designed RD did not conduct comprehensive venous gas emboli tests for altitude diving. That's the kind of evidence that I'd be interested in. IMHO, applying RD to altitude dives turns you and your buddy into guinea pigs.

Thanks for sharing your experience.

My intent is not to disparage the RD method. I only know that it is rather new. I do not want to sidetrack this thread on a discussion of the advantages/disadvantages of RD since it is only peripherally related to the original post.

 

[Divedoggie]

What specific intervention(s) did DAN physicians recommend?

Did the treatment team ever consider anti-inflammatory treatment? Just curious.

That's interesting.

Were sodium, potassium, calcium, and magnesium blood levels ever assessed?

I have read a couple of journal articles on the use of magnesium to treat tetany (sustained muscular contraction) in certain patients. If the patient's blood tests were otherwise normal, then I think their reason for administering magnesium was a little strange. Then again, I'm certainly not an expert on this.

Interestingly, magnesium may have been helpful for other reasons. Magnesium can serve as a cerebral and peripheral vasodilator. It is also a well-described non-competitive antagonist of the NMDA receptor found in neurons. Blockade of the NMDA receptor has been shown to prevent/minimize excitotoxic neuronal death. Both of these functions of magnesium would be helpful in the setting of ischemic stroke (or possibly AGE).

Given the limited clinical info we have on this thread, DCI would have placed very high on the differential. However, radiculopathy should have been considered as well. It's too bad that a comprehensive neurological exam wasn't performed and repeated at regular intervals. It would have been informative to localize sensory and motor deficits during the acute course.

Thank you very much for patiently answering all of the questions. Eight dives in one day with several relatively fast ascents and short surface intervals at high altitude adds up to significant decompression stress on a diver.

I think DAN recommended transport to hyperbaric facility
No anti-inflammatory treatment.
Electrolytes were ok:
Potassium was low @ 3.4, normal range is 3.5 - 5.1
Sodium: 136 which is low normal.
Calcium: 8.9 normal
The entire panel was unremarkable overall.

Very interesting info on Magnesium.
Given more info, I am beginning to think that the incident wasn't DCI.

Apon further questioning, the patient has experienced neurological symptoms periodically for a few years. He said that a few years ago the bottom of his right foot itched chronically. No rash, foreign object, or lesion. His right calve would occassionally feel warm like "a sunbeam striking on baseball sized area." He also said that he has reached into upper cabinets a few times over the last year and felt the same sensations that he felt underwater on that dive.

Here is my new theory:

In this case the high CK value is indicative of severe spasm and hard work throughout the day. He may have been toughing out a sore back/spasms all day.

The group was doing a long safety stop in a supine position with chin down after hours and hours of diving in a prone position with chin straining upward.

When he rolled over at the end of the safety stop and began ascending toward the exit point, a bulging disk or other inflammated tissue impinged the vulnerable nerves that had already been at risk. This explains the first symptoms being felt underwater.

Everyone was convinced of DCS and convinced O2 was the preferred treatment, so we believed that was what he was responding to. The Valium drip alleviated spasm, helped realign disk or tissue, and the magnesium prevented neuronal necrosis.

The attending Physician never believed it was DCS, and maybe he was right. He didn't test for radiculopathy, but perhaps suspected it and suggested patient follow through at home.

I'm calling my friend now to suggest a neuro exam before he does any lifting or risky behavior! I've been so convinced of DCS, he is going to think I'm nuts.

 

[Bubbletrubble]

Very interesting info on Magnesium.
Given more info, I am beginning to think that the incident wasn't DCI.

Bear in mind that just because he was given magnesium doesn't necessarily mean that it "helped" or prevented excitotoxic neuronal death. It's important to accept that his improvement, relative to administration of magnesium and/or diazepam, could have been purely coincidental.

Apon further questioning, the patient has experienced neurological symptoms periodically for a few years. He said that a few years ago the bottom of his right foot itched chronically. No rash, foreign object, or lesion. His right calve would occassionally feel warm like "a sunbeam striking on baseball sized area." He also said that he has reached into upper cabinets a few times over the last year and felt the same sensations that he felt underwater on that dive.

Very interesting.

I think that your hypothesis is certainly plausible. In the original post, you mentioned that the instructor did a safety stop on his back. It's very easy to place the cervical vertebrae in an awkward, non-neutral position when doing that. Even the standard prone horizontal dive position can put significant strain on the vertebrae/vertebral discs/spinal roots. Based on the info discussed in this thread, it sounds like motor paralysis was localized to the right side, correct? It's peculiar that he experienced paralysis in both the right hand/arm and right leg. This argues against spinal root impingement (which would need to occur at two different levels) and supports either damage to the corticospinal tracts in the spinal cord (at/above the cervical level) or a lesion to upper motor neurons in the motor cortex (left side of brain). I'm not sure how the sensory deficits fit into the clinical picture since sensory tracts run in a slightly different location within the spinal cord and the somatosensory cortex is distinct from the motor cortex in the brain. It also appears as though somatosensation wasn't monitored as closely as the motor function. In any case, it sounds like a trip to the neurologist might be in order. Be forewarned, the workup could be fairly extensive and costly for such an issue (might involve MRI studies).

There's a lot of stuff going on here and it's really difficult to rule out DCI based on the sequence of events, so I'm not surprised that the experts haven't been able to zero in on a concrete diagnosis.

 

[boulderjohn]

@boulderjohn

I suspect that whoever designed RD did not conduct comprehensive venous gas emboli tests for altitude diving. That's the kind of evidence that I'd be interested in. IMHO, applying RD to altitude dives turns you and your buddy into guinea pigs.

I understand the point of view. It has been discussed.

As I understand it, the rationale for believing that altitude is not a factor in DCS is based on two things:

1. a mathematical comparison of the difference in surfacing at altitude with doing equivalent additional time at decompression stops, seeing little theoretical difference
2. some UTD divers have done dives at high altitudes (Lake Tahoe) using RD with no ill effects.

Please note that I am only serving as a reporter, not an advocate, in relaying this information.

 

[jridg]

Extremely interesting items - here are some opinions from someone NOT experienced in altitude diving:

- 8 dives is too many. I have done six dive days with students in the past and was completely wiped out even though the dives were 'relaxed' and on Nitrox - and this was at sea level.

- Was the instructor hydrating all day between dives? You mentioned he dives dry - does he have a pee-valve? I have found that after installing my pee-valve, I hydrate a LOT more when diving dry.

- His potassium was low - please correct me if I am wrong, but can't this contribute to muscle cramps? Was he eating properly all day? I would doubt that a little given the schedule.

- IMHO - and take that for what it's worth - limiting your instructional staff to six per day (double what you are allowed to 'do' to students) and ensuring Nitrox and proper hydration/eating habits would seem prudent.

Hope he's doing well and this works out in the end. 'Scary' is just the tip of the iceberg.

 

[Divedoggie]

Extremely interesting items - here are some opinions from someone NOT experienced in altitude diving:

- 8 dives is too many. I have done six dive days with students in the past and was completely wiped out even though the dives were 'relaxed' and on Nitrox - and this was at sea level.

- Was the instructor hydrating all day between dives? You mentioned he dives dry - does he have a pee-valve? I have found that after installing my pee-valve, I hydrate a LOT more when diving dry.

- His potassium was low - please correct me if I am wrong, but can't this contribute to muscle cramps? Was he eating properly all day? I would doubt that a little given the schedule.

- IMHO - and take that for what it's worth - limiting your instructional staff to six per day (double what you are allowed to 'do' to students) and ensuring Nitrox and proper hydration/eating habits would seem prudent.

Hope he's doing well and this works out in the end. 'Scary' is just the tip of the iceberg.

Good observations. Good advise.
DAN tends to think that this was NOT a DCI incident. DCI can't wholly be eliminated from the equation, but there were other factors involved.

The combination of too many dives, exhausting work, personal/emotional stress that my friend was experiencing prior to diving, combined with not eating enough or hydrating enough, and the possibility of cervical pressure on the spine, could have created a nasty cocktail.

We are having a staff meeting this week and we will all get a lot more info at that time.
As far as policy changes go.. It looks like our weekend trips will turn into 3 day trips. That way the groups can remain small and the dives can be divided over several days, with relaxed and long SI times and lots of eating and hydrating.

 

[mikerault]

One thing no one has mentioned, since he was diving dry (did he have a pee-valve?) was he maintaining proper hydration? Improper hydration can cause a DCS hit and dry diving can sometimes lead to not properly hydrating since you can't wee in your wetty...

Mike

 

[smellzlikefish]

While the eight repetitive dives were very possibly an issue, what struck me was that the paralysis was isolated to the right side of his body and he seemed to be having mostly neurological symptoms which, when combined sounds more like an embolism than typical DCS. I believe AGE's tend to paralyze your body by right and left sides like in a stroke, while DCS hits tend to paralyze from some point (presumably where the bubbles are) down. Furthermore, while his computer didn't show any fast ascents, it also didn't look for factors such as skip-breathing or mucus blocks in his lungs. Finally, he was shallow where the greatest relative pressure increases, and thus greatest volumetric expansions of air, happen.

 

[lizardqueen]

I don't have the training of all the doctors and DMs on this thread, so I've always gone by the limits I learned on the mike ball + peter hughes boats - which is 5 dives/day max. I'm wondering if a lot you on this board exceed that, and if you do, is it because you use nitrox?

I haven't tried nitrox since I usually have air leftover when everyone is getting back in the boat, and I'd rather have the leeway on my depth.

If it isn't because of the nitrox, are you just cowboys?