Chronicle of an older diver

Being a layman when it comes to physiology and medicine, it is difficult for me to review this 2004 book by Michael B. Strauss, MD and Igor V. Aksenov, MD, PhD with authority. So I’ll limit my comments to what I think I’m qualified to talk about. I’m happy to take harsh criticism on this one, as it’s a little out of my league. There are more favourable reviews than this one around, including readers on Amazon, and the book is not without its good points.

This is a very complete book, and full of comprehensive lists covering various topics. It divides into three major parts: The Underwater Environment, Physiological Responses to the Underwater Environment, and Medical Aspects of Sport Diving. Being rather encyclopaedic it’s hard to read from cover to cover, but its organization also makes it hard to use as a reference. For instance, decompression sickness appears in more than a dozen places in the book. I would have liked to have seen topics clustered together more so that if I was interested in a particular topic, I could read everything I needed to know about it, from theory to treatment.

There are also a number of errors and important omitted information. Simple errors like page 12 where it gives the comparative densities of sea water and fresh water in pounds per square foot (rather than pounds per cubic foot) can be attributed insufficient editing, but statements like “the theoretical depth limit for diving with air based on an oxygen toxicity limit of 2.0 ATA is….” should have been put into context, in this case with the generally accepted limit of 1.4 ATA in the working portion of the dive, and 1.6 during decompression, even if that is done elsewhere in the book.

There are also imprecise statements like “halving the depth results in doubling the saturation”. Something is either saturated or it isn’t. Doubling the percentage saturation would have been more correct wording, but still wrong because it doesn’t take into account the pressure of the atmosphere. To double the percentage saturation from 99 feet requires ascending to 33 feet.

I started to read the book and put yellow post-it notes in the places where I thought the text was wrong or misleading. One statement that particularly annoyed me was that the pressure change from full to empty would be less in an aluminum tank than in a steel one of the same capacity. What baloney! If you take 80 cubic feet of air and compress it, it weighs the same (about 6 lbs) no matter what the tank material is or what pressure it’s compressed to.

There are other curious omissions like the description of carotid-sinus reflex. It mentions that it may be caused by a hood that’s too tight, which may well be true, but fails to mention dry suit neck seals, where this problem has been known to cause fatalities.

However, the one that tops them all in my mind, although I wouldn’t call it a serious error, is with regard to the Patent Foramen Ovale (PFO). It said that according to one report, “about 1/3rd of divers treated for serious symptoms of decompression sickness had this heart problem”, then it goes on to say that “PFOs are observed in one-quarter to one-third of the population”. What does that tell us? If 1/3rd of the population has a PFO, you’d expect, all else being equal, that 1/3rd of the divers with serious DCS would have it as well! If you saw less than that, you could say that a PFO protects you from DCS. Now if only 1/4 of the population has a PFO, but 1/3rd of the stricken divers do, then there may be something to it, but you can hardly call the statements conclusive enough to justify  “This observation points to the one reason some divers are more likely to get decompression sickness than others”. Now I’m not saying the PFO isn’t a risk factor for DCS, just that “this observation” doesn’t support that contention.

I’m glad I borrowed this book from the library instead of buying it. After a dozen post-its I gave up reading it thoroughly at page 90. It’s too bad that errors and poor organization cloud what seems to be a wealth of good information in this well-illustrated book. Perhaps if they address these issues in a subsequent edition I’ll consider adding it to my own library.