The carbon monoxide story, continued. Part 1.6: A cosmic coincidence
1.6 A cosmic coincidence
Alright! I had CO gas, a breathing circuit to both administer it and eliminate it, I was able to measure blood CO levels, and I had the hospital Ethics Board approve the study. No way I could avoid doing it.
Of course I would be the first subject. Ludwik placed an intravenous catheter in my hand. The others in the lab crowded around as they strapped the mask on my face and connected the tube to the breathing apparatus. Josh Rucker turned the handle on the regulator to the tank with the carbon monoxide. I could smell some metallic odour. I knew CO has no smell, so this was the smell of gas that has been in a metal tank. The other students were looking after other issues, measuring my heart rate and the oxygenation in the blood using a pulse oximeter, my blood pressure, taking blood samples and running them to the lab. Not being a dog, we actually didn’t know how long it would take to get my blood level to 12%. I can’t say I felt perfectly well as my CO levels were rising, but I knew that my blood CO levels were too low to result in any symptoms. Just psychological I told myself. Just ‘nerves’.
There was one of 2 protocols that were going to be carried out. On one protocol I would breathe oxygen at my comfortable breathing level. In the other protocol, I would have to keep up my breathing with the rate the lab guys were blowing oxygen into the circuit. I reached into an envelope and pulled out a folded paper. The boys read it and adjusted the flow into the circuit accordingly. My job was then to breathe just that gas blowing into the circuit. Blood was drawn every 5 minutes for about the next 2-3 hours. After the study was done, I hyperventilated to eliminate the rest of the CO.
We all felt the excitement. The first ever human subject was exposed to CO, then had it eliminated with this new method. It was a bit of a sensation as we all realized that what just transpired was a unique and important moment, not just in our lives, but in medical in history.
Over the next few weeks we studied Ludwik, and then we found five more male anesthesiologists who would volunteer for the study. Honestly, they had no qualms other than getting an i.v. The students analyzed the data from each subject. They graphed the COHb data against time and calculated the half-time of elimination. They then graphed this half time against the minute ventilation. They brought me the data. Hmmm, it’s a bit scattered, but I could see a real trend. I asked them to divide the minute ventilation by the subject’s weight, to get rid of the variation due to weight. Bingo
The graph clearly showed that as the amount of breathing required to get to about 80% of the way to the rate of CO elimination in the hyperbaric chamber was easily do-able and sustainable: about 15 liters of air per minute. For me, this is about how much I breathe when I go up a flight of stairs. I mean, this is no sweat!
While doing the analysis, it was Ron, and Alex, who I think noticed that strangely enough, the people told to breathe normally, were breathing almost as much as those for whom we set higher ventilations. Why was that they wanted to know.
Well, maybe just by having a mask on their face made them breathe more. But Ron noticed that when they were getting the CO in air, they were not breathing as much despite also wearing the mask. The differences were dramatic. There was no denying it. I couldn’t understand it. Breathing oxygen is supposed to make you breathe less…not more. This must be some sort of artefact, I thought. I suggested that Ron test some people here in the lab breathing on air and O2 without knowing which.
He brought me the data: they breathed more with the oxygen. No way! “Ron, do me”.
They strapped a mask to my face and I sat with my back to the tubing and tanks. I read an article from a science magazine and paid no attention to them. The results: when they switched me from air to oxygen, my breathing rate went up. When they “clamped” by PCO2 at my resting level, my breathing rate went up dramatically—to the level where, if I were being treated for CO poisoning, my elimination rate would be more than 80% of that of the hyperbaric chamber! Oxygen seems to a respiratory stimulant.
But it can’t be! All the years of medical school and specialty training. Something wrong here. If this is true we can’t possibly be the first to have noticed this. I phoned Steve in Kingston. He said he never heard of that either. Two hours later he called me back. He had an article by a fellow called Becker, published in Journal of Applied Physiology who not only described this exactly but gives an explanation. The article was published in 1997 and there was little since then. Its true, but no one seems to know it.
Hyperventilation was effective in the dogs, but we forcefully ventilated them with a ventilator. Humans just won’t voluntarily sustain an increased ventilation sufficient to get rid of the CO faster than just an oxygen mask. That makes the method a lab curiosity.
Now this: The oxygen we give patients to treat their CO poisoning is a respiratory stimulant. Go figure. But when we keep their PCO2 normal they hyperventilate like crazy and don’t even know they are doing it, all the while quickly shedding all their CO. What a gift!
How often does such a cosmic coincidence occur in human history? Flemming noticing the gaps in bacteria around fungus balls in the petrie dishes, which he was too lazy to wash when he left on vacation. Banting and Best noticing the flies around the urine in the diabetic dogs. And now implementing our isocapnia to enable hyperventilation actually stimulates the hyperventilation required to get rid of the CO.
Cosmic coincidence. But since merited credit is seldom given, we will take it this one!
