I am always amazed at the pace of progress, particularly in diving, where it seems a 10-20 year cycle is in play for better understanding new technologies, new techniques, and their implications on human factors. A recent article from the Divers Alert Network about pseudoephedrine and diving illustrates this point quite well…

http://www.diversalertnetwork.org/medical/articles/Pseudoephedrine_Enriched-Air_Diving

Rewind twenty years, and it was rather commonplace for an openwater dive instructor to suggest that over the counter decongestants were a suitable remedy for a student diver who was having difficulty equalizing in shallow water. Between the cold water in your ears, a tightly fitting hood, and the newly experienced effects of pressure, even in the shallows, equalization poses problems for many new divers. A little Sudafed, and you’re good to go, right?

I was among those with equalization problems from the beginning. It was just a foreign concept, and I had some trouble making air go where it needed to go in my ears and sinus cavities to get past the discomfort. I tended to opt for the Sudafed approach which helped, but didn’t solve the problem. As I got more accustomed to equalization techniques, I put the Sudafed away for days when I may have been legitimately congested but needed to dive for work, and I still do this for shallow dives. However, those monsters that lurk in the depths don’t like drugs, and much as the DAN article states, pseudoephedrine and high partial pressures of oxygen don’t mix too well.

There were two instances early in my diving career which scared the bejesus out of me, and raised concerns for my instructor at the time for my suitability for deep diving, which in hindsight was a warranted concern. On one air dive to 170fsw in the Gulf of Maine, I experienced what was believed to be extreme nitrogen narcosis – so bad that I don’t remember being down there and was directed up the line within a very short time. Another instance was out wreck diving on the U853 (about 120fsw) using nitrox and felt incredibly dizzy, though regained enough composure to call the dive myself. On both occasions, I had taken a decongestant containing pseudophedrine. In both instances, the pO2 was elevated beyond what would be experienced within normal recreational diving depths on air. Now of course the confusion are the symptoms. At the time I, and my instructor, were believing this was purely narcosis. There are reasons to suspect this given the depth, however I have since done numerous similar dives without any trouble, and far deeper dives, though with no decongestant taken.

At the time, again 20 years ago, there was only speculation that pseudoephedrine posed any increased risk of oxygen toxicity, and with mainstream nitrox being relatively new, the signs and symptoms of oxtox (CON-V-E-N-T-I-D) were presented as distinctly different from signs of nitrogen narcosis. Today, as illustrated in the DAN article, there remains confusion. The visual and dizziness issues caused from oxtox can be strikingly similar to narcosis. When exacerbated by a drug, it is nearly impossible to determine the true cause of the experience.

Bottom line – we don’t drink and drive because drinking impairs your judgement. We shouldn’t drink or otherwise do any drugs and dive without understanding how they may impact your physiology while under pressure. Unfortunately, there remain more questions than answers, though that of course leaves much work to do for those pursuing a new life in the sea.