skin bends in Coz.,,

[LavaSurfer]

Hi Dr D.

hope all is well on the eve of the arrival of Rita ! i understand you had to evacuate...

i had a question about your response below....

are you saying that a"Valsalve Manuever" will help me keep the PFO shut, to avoid the left to right shunting ?

or will it aggravate the flow across ...?

if it helps to keep the shunt closed, then wouldn't it be a good idea to do it at the safety stop ? while the nitrogen bubbles are still smaller...

thank you for all your time and expertise...

juergen

juergen
I am sure the good Doc will pipe in but the Valsalva Maneuver causes a reverse momentary reverse pressure across the heart chambers where the left side has a lower pressure and causes blood to flow from the Venus to the Arterial flow. Venus blood contains the small bubbles and gasses prior to removal in the lungs and by performing any Valsalva type Maneuver that "Dirty" blood enters the arterial flow and that is where the risk lies.

Sneezing, Coughing, equalizing your ears, bearing down as in defecating or lifting heavy objects like bodies and tanks up a ladder all can cause this momentary bypass of gaseous blood.

In other words, all of the above are a bad thing after diving especially if you have a PFO.


http://divermag.com/archives/april99/divedoctor_apr99.html

Scooter

 

[waldick]

That's what i thought...but just wanted to make sure...

i was referrred to DAN docs in Toledo...i already have a call in to them....

more to come...

juergen

 

[waldick]

Ok, i gave my history, symptoms and prior diagnosis to the Doc that DAN referred me to and this is the response i got:

"First of all, there are no data suggesting that a PFO is a contraindication to diving. There are some people who feel that a PFO should be a prohibition, but given that fact that 30% of all divers have a PFO, it is not likely that it causes a high risk. Abdominal cramps and diarrhea are not part of a decompression syndrome, and given the fact that nearly 100% of people who go to Cozumel get abdominal cramps and diarrhea, whether diving or not, I am certain that that symptom was not related. In addition your symptoms 10 days after diving are also not likely to be related to diving.

Dr. Piccolo is right in not treating an uncomplicated case of skin bends. In the absence of other findings, recompression therapy is not needed. I would be concerned about a pulmonary embolism 10 days after diving. This is a complication of the airplane ride and prolonged sitting, not of diving. You need to be tested for that although by now findings may be absent.

Data on stroke and PFO are still not well established. There is some suggestion that a large PFO is a risk for stroke, and many cardiologists advocate closure. Looking at the complications of closure, and the residual PFO rate after closure, in the absence of any stroke symptoms, closure is likely to be more risky that non-closure. Remember that 30% of the population has a PFO, and closure would cause an inordinate number of complications in these individuals whose risk for an embolic events is very low.

You should be cognizant of your nitrogen load when diving. Many computers are liberal and would put you in a decompression stop situation based on USN tables. To get bends, you must have bubbles. These are often in the veins, and would not be a problem without a PFO. Diving bubble free is possible. This can be done by being very conservative about depth an bottom time (Canadian/DCIEM tables would be a good guideline for bubble free diving). Nitrox might help, but again there are no data to indicate that this would be a solution to diving bubble free.

Fred Bove, MD, PHD"


so now i guess i have to decide if i want to try the tables or nitrox suggested or just hang up the fins and try another hobby...

 

[cameron]

DCIEM tables are ancient. depth/time considerations are certainly important, but how you conduct the dive is of utmost concern. Watch out for zigzag profiles on the bottom with quick asscents and descents. " ohh theres something...Ohh theres something else" "up down up down up down" NOT GOOD!! I think if we all concentrated on our profiles more, we would be in better shape. descend to the maximum depth of the dive with a nice 30 foot per minute ascent rate. Thats really what modern tables call for, but most divers don't really follow them... I guess it requires a fair bit of dicipline

 

[Web Monkey]

That was a great writeup from the doc. He's not telling you to stop diving, just learn to be bubble-free.

Don't build up too much nitrogen (dive towards the left side of the table) and come up slow. You'll feel better.

In fact, everybody would feel better with a slow ascent, especially in the last 15 feet.

Terry

You should be cognizant of your nitrogen load when diving. Many computers are liberal and would put you in a decompression stop situation based on USN tables. To get bends, you must have bubbles. These are often in the veins, and would not be a problem without a PFO. Diving bubble free is possible. This can be done by being very conservative about depth an bottom time (Canadian/DCIEM tables would be a good guideline for bubble free diving). Nitrox might help, but again there are no data to indicate that this would be a solution to diving bubble free.

Fred Bove, MD, PHD"


so now i guess i have to decide if i want to try the tables or nitrox suggested or just hang up the fins and try another hobby...

 

[Dr Deco]

Hello readers:

“Valsalva-like Maneuvers

There are currently three aspects to the arterialization of venous gas bubbles.

[1] The first is, naturally, the presence of bubbles in the venous system. Individuals, for unknown reasons, do not produce the same quantity of decompression gas bubbles. If you produce copious numbers of bubbles, the risk of arterialization would be greater.

[2] Next one needs sufficient gas loads in the tissues. Low doses of tissue nitrogen [i.e., shorter dives] will prevent the formation of decompression gas bubbles. Likewise, slow ascents will prevent Boyle’s-law expansion and a concomitant reduction in the Laplace [surface tension] pressure. Slow ascents force microbubbles to remain small and eventually shrink. Those in capillaries will not find their way into the venous return.

[3] The arterialization process occurs either through pulmonary shunts or through a PFO. Both of these mechanisms of passage are greatly added by an increase in right ventricular systolic pressure (pulmonary shunts) or right atrial pressure (PFO). Valsalva-like maneuvers (see reference below) assist both mechanisms.

Dr Deco :doctor:

References :book3:

Balestra C, Germonpre P, Marroni A.
Intrathoracic pressure changes after Valsalva strain and other maneuvers:
implications for divers with patent foramen ovale. Undersea Hyperb Med. 1998 Fall;25(3):171-4.

Scuba divers with patent foramen ovale (PFO) may be at risk for paradoxical
nitrogen gas emboli when performing maneuvers that cause a rebound blood loading
to the right atrium. We measured the rise and fall in intrathoracic pressure
(ITP) during various maneuvers in 15 divers. The tests were standard isometric
exercises (control), forceful coughing, knee bend (with and without respiration blocked), and Valsalva maneuver (maximal, gradually increased to reach control ITP, and as performed by divers to equalize middle ear pressure).

All the maneuvers, as well as the downward slope of ITP at the release phase, were
related to the control value. ITP levels were significantly higher than the standard isometric effort during a breath-hold knee bend (172%), cough (133%), and maximal Valsalva (136%) whereas "usual" Valsalva maneuvers produced ITPs significantly lower than the standard (28%).

 

[waldick]

Thanks Doc,

that's what i thought...

so, after all the reading and advice, i have come up with the following plan:

1) get nitrox certified
2) limit my depth to 60 feet
3) dive only 75% of air dive tables
4) increase the safety stop
5) decrease my max assent rate to 1/2 standard
6) equalize by swallowing or moving my jaw to avoid "valsalva man."


what do you think....?


thanks,

j. waldick

 

[waldick]

one other question...

would using a rebreather help in my situation ?

j.waldick

 

[coldwaterdivergirl]

using a rebreather helps EVERY situation

 

[drdiver1952]

I just want to say I happened on this thread just this morning and found it one of the most interesting and informative ones I've ever read. Thanks to all contributors.