R22 Discussion Group

On Jun 10, 2024, at 10:54 PM, Ric Stott <ric at stottarchitecture.com> wrote:

Hi Ric,

So far, I’ve had both knees, my right hip, a pacemaker (A-Fib), and cataract surgery on both eyes.  I’m slowly going bionic!  So far, the results of all this parts replacement have been good.

I just got back from my second PT session.  Besides walking with a walker about 400 ft, I learned how to use stairs, a ramp, and getting into/out of of a car.  I’m a little sore; but, it’s much easier than the knees were!

I had an interesting experience with my pacemaker the first time I tried to scuba dive with it.  It turns out the “controllers” for breathing rate and heart rate are both located in the same part of the brain in the medulla.  But, they apparently don’t talk to each other.  Both controllers receive the same signal from the body to increase/decrease oxygen supply.  So, one controller causes the heart rate to go up and the other controller causes the breathing rate to increase.  In many mass transfer devices, like the lungs, there are often two rate limiting factors.  In the case of the lungs, the rate of blood flow controls how much oxygen/carbon dioxide can be transferred from the blood across the avioli membrane into/out of  the air sacs.  But, the breathing rate controls how fast that gas can be transferred in and out of the lungs.  Normally, the two controllers ramp up and down together; but, one is not influenced by the other.  They just get the same input signal from the body and each does their thing.  But, when you get a pacemaker, the default max heart rate is set to 95 bpm.  So now, underwater the body is calling for more oxygen.  The breathing rate goes up, but the heart rate is limited by the pacemaker.  Slow blood flow in the lungs prevents enough gas exchange to satisfy the body’s need.  The body keeps calling for more oxygen and the breathing rate keeps going up to supply it.  But, the heart rate just keeps plodding along, limited to 95 bpm.  On land, this would be no big deal.  You would just get out of breath and stop.  But, underwater, you go thru a tank of air VERY quickly.  In my case, I used up my air and had to buddy breathe from my diving partner’s tank to safely get back to the surface.  This included a decompression stop to prevent the bends.  This was the first time I’ve ever had to buddy breathe except in training exercises.

To solve this issue, my cardiologist laid a plastic disk on my chest.  The antenna in the disk linked with the implanted pacemaker.  They remotely reprogrammed my pacemaker and reset the max heart rate to 190 bpm.  I haven’t had any issues scuba diving since then.  What a marvelous age we live in!

Roger Pihlaja
S/V Dynamic Equilibrium
1978. Sanford, MI

Sent from my iPhone

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ROGER PIHLAJA

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