Author: jclarke45
After the Heart Attack – The Healing Power of Athletic Passions
There is nothing quite like a heart attack and triple bypass surgery to get your attention.
Even if you’ve been good, don’t smoke, don’t eat to excess, and get a little exercise, it may not be enough to keep a heart attack from interrupting your life style, and maybe even your life.
Post-surgical recovery can be slow and painful, but if you have an avocational passion, that passion can be motivational during the recovery period after a heart attack. There is something about the burning desire to return to diving, flying, or golfing to force you out of the house to tone your muscles and get the blood flowing again.
My return to the path of my passions, diving and flying, began with diet and exercise. My loving spouse suggested a diet of twigs and leaves, so it seemed. I can best compare it to the diet that those seeking to aspire to a perpetual state of Buddha-hood, use to prepare themselves for their spiritual end-stage: it’s a state that looks a lot like self-mummification. Apparently those fellows end up either very spiritual or very dead, but I’m not really sure how one can tell the difference.
The exercise routine began slowly and carefully: walking slowly down the street carrying a red heart-shaped pillow (made by little lady volunteers in the local area just for us heart surgery patients). The idea, apparently, is that if you felt that at any point during your slow walk your heart was threatening to extract itself from your freshly opened chest, or to extrude itself like an amoeba between the stainless steel sutures holding the two halves of your rib cage together, that pillow would save you. You simply press it with all the strength your weakened body has to offer against the failing portion of your violated chest, and that pressure would keep your heart, somehow, magically, in its proper anatomical location.
I am skeptical about that method of medical intervention, but fortunately I never had occasion to use it for its avowed purpose.
Eventually I felt confident enough to ditch the pillow and pick up the pace of my walks. In fact, I soon found I could run again, in short spurts. It was those short runs that scared the daylight out of my wife, but brought me an immense amount of pleasure. It meant that I might be able to regain my flying and diving qualifications.
Three months later I was in the high Arctic with good exercise capability, and most importantly the ability to sprint, just in case the local polar bears became too aggressive on my nighttime walks back from the only Ny-Alesund pub.
After that teaching adventure, I prepared myself for the grinder that the FAA was about to put me through: a stress test. Not just any stress test mind you, but a nuclear stress test where you get on a treadmill and let nurses punish your body for a seeming eternity. Now, these nurses are as kindly as can be, but they might well be the last people you see on this Earth since there is a small risk of inducing yet another heart attack during the stress test. Every few minutes the slope and speed of the treadmill is increased, and when you think you can barely survive for another minute, they inject the radioisotope (technetium 99m).
With luck, you would have guessed correctly and you are able to push yourself for another long 60-seconds. I’m not sure exactly what would happen if you guess incorrectly, but I’m sure it’s not a good thing.
And then they give you a chance to lie down, perfectly still, while a moving radioisotope scanner searches your body for gamma rays, indicating where your isotope-laden blood is flowing. With luck, the black hole that indicates dead portions of the heart will be small enough to be ignored by certifying medical authorities. (An interesting side effect of the nuclear stress test is that you are radioactive for a while, which in my case caused a fair amount of excitement at large airports. But that’s another story.)
The reward for all the time and effort spent on the fabled road to recovery, is when you receive, in my case at least, the piece of paper from the FAA certifying that you are cleared to once again fly airplanes and carry passengers. With that paper, and having endured the test of a life-time, I knew that I’d pass most any diving physical.
Having been in a situation where nature dealt me a low blow and put my life at risk and, perhaps more importantly, deprived me of the activities that brought joy to my life, it was immensely satisfying to be able to once again cruise above the clouds on my own, or to blow bubbles with the fish, in their environment. Is there anything more precious that being able to do something joyful that had once been denied?
Without a doubt, the reason I was able to resume my passions was because I happened to do, as the physicians said, “all the right things” when I first suspected something unusual was happening in my chest. The symptoms were not incapacitating so I considered driving myself to the hospital. But after feeling not quite right while brushing my teeth, I lay down and called 911. The ambulance came, did an EKG/ECG, and called in the MI (myocardial infarction) based on the EKG. The Emergency room was waiting for me, and even though it was New Years’ eve, they immediately called in the cardiac catheterization team. When the incapacitating event did later occur I was already in cardiac ICU and the team was able to act within a minute to correct the worsening situation.
Had I dismissed the initial subtle symptoms and not gone to the hospital, I would not have survived the sudden onset secondary cardiac event.
The lesson is, when things seem “not quite right” with your body, do not hesitate. Call an ambulance immediately and let the medical professionals sort out what is happening. That will maximize your chances for a full and rapid recovery, and increase the odds of your maintaining your quality of life.
It will also make you appreciate that quality of life more than you had before. I guarantee it.
A Salute to Warriors
It was a moment in time that no one had expected. Through a twist of fate I found myself standing in the midst of warriors; warriors dressed in civilian clothes, waiting for a ride somewhere. They sat on the floor, propping themselves up against walls, wasting no energy, efficient even in their resting.
They had the look, those warriors. There is no mistaking that look once you’ve seen them; handsome, intelligent, lean and fit. They looked like the type of men that growing boys always want to be. They were in their prime.
As I walked among them, they noticed me, undoubtedly. They sized me up, but mostly kept silent. A few talked softly to their near-by friends about whatever interested them, to pass the time. They were clearly not a rugby or football team, all full of themselves, headed off for a game. They were quietly confident, having done this so many times before.
One of them had body art and dark features. His look said Navy, and since he sat alone I paused in front of him. If he was indeed a Navy man, I wanted to wish him well.
“You fellas shoving off?”
It was a harmless question, since the answer was obvious. Of course they were. But that warrior lowered his head, did not speak. It looked like he regretted being singled out, as if he would break some code of silence if he spoke to someone who was not one of them. As they say, his silence spoke volumes. I then knew him for exactly who and what he was, and both admired and respected him and his silence.
Before the moment became too awkward, one of his buddies, twenty or so feet away, spoke, drawing my gaze, flashing an easy smile, removing attention from a pinned down comrade. That’s instinctive for them; protecting their own.
“Yes, we are,” is all he said, and was all he needed to say.
I gave him a thumbs up. “Good luck fellas,” I said; and I meant it with all my heart. I was thankful that one of them had given me a chance to wish them all well.
If only my good wishes had been more effective. When I saw the photos in 2011 of those lost in Afghanistan, which included that dark-haired SEAL with the decorated arms, I shuddered. I don’t know if those lost in the helicopter with him were some of his travelling buddies that day that I walked among them, but they were all fine, fine men. The loss of any of them is a loss to the world I believe.
I salute them all.
Blood, as a Delicacy, Is Underrated
Those words earned me a first place prize of $20 in a contest for the best first line in a comic vampire novel. The contest was held during the 2010 Ozark Creative Writers’ Conference in Eureka Springs, Arkansas.
Not that I would ever write a vampire novel, comic or otherwise, but I guess it proved I can be succinct – from time to time. I admit that comes as a shock to those who know me best.
What amazed me about that line, and winning, was that it was my first submission for a writing competition. Now, if I can just keep it up. Let’s see, that was $3.33 per word, so a 100,000 word novel would earn me …
Holy Mackerel! What am I doing wasting time blogging?
OK, seriously, what is it about the European cultures and blood? Have you ever had blood pudding?
I once stood in a working man’s cafeteria line in Geesthacht, Germany, on the Elbe River, paralyzed before a large stainless steel pan filled with — blood, or at least something really, really bloody. It wasn’t like rare steak. It was more like a pan from an autopsy table.
My German friends told me the “pudding” was really fresh. Did that mean there was a meat packing plant close by? Maybe it’s just me, but any recipe that starts off with one quart of pig’s blood is just not that appetizing. I know, it’s a cultural thing.
I didn’t gag, but I also didn’t eat much of anything for lunch that day. Maybe some very white bread, and milk — nothing with shades of pink — that’s for sure.
Which brings me to the observation that perhaps I could write the first line of a comic vampire novel, but I would probably throw up before finishing the first chapter.
Guess I’m just squeamish.
Of Mussels and Whales
It was a coincidence forty years in the making. I was recently at the Scripps Institute of Oceanography, talking to Scripps professor and physician Paul Ponganis about deep diving whales. He told me about the recent discovery that Cuvier’s Beaked Whale, an elusive whale species, had been found to be the deepest diving of all whales.
How deep I asked? One whale dived to 9,816 feet, about 3000 meters. At that depth, water pressure exerts a force of about 4400 pounds per square inch (psi), equal to the weight of a Mercedes E63 sedan pressing on each square inch of the whale’s ample body surface. That is a seriously high pressure, a fact that I knew well since I had once created that much pressure, and more, in a small volume of seawater in a pressure vessel at the Florida State University.
Early in my science career, I published my work on the effect of deep ocean pressure on intertidal bivalves, a mussel (Modiolus demissus) being among them. I found that if you removed the hearts of such molluscs (or mollusks) and suspended them in seawater, they would continue to beat. Furthermore, those excised hearts would beat when subjected to 5000 psi of hydrostatic pressure. As if that wasn’t surprising enough, the slight genetic differences between Atlantic subspecies and Gulf Coast subspecies of mussels resulted in the isolated hearts responding slightly differently to high pressure.
That was a remarkable finding I thought since none of those mussels had ever been exposed to high pressure; ever as in for millions of years. (This study occurred long before the discovery of deep sea vents and the almost miraculous growths of deep sea clams.)
Eventually, my research transitioned from invertebrates to humans. Humans, like intertidal mussels and clams, are not normally exposed to high pressure. But like my unwilling invertebrate test subjects, sometimes humans do get exposed to high pressure, willingly. But not so much of it. Deep sea divers do quite well at 1000 feet seawater (fsw), manage fairly well at 1500 fsw, but don’t fare well at all at 2000 fsw. That depth seems to be the human pressure tolerance limit due to the high pressure nervous syndrome, or HPNS. At those pressures, cell membranes seem to change their physical state, becoming less fluid or “oily” and more solid like wax. Cells don’t work normally when the very membranes surrounding them are altered by pressure.
The Beaked Whale is genetically much more similar to man than are mussels. Therefore, man is far more likely to benefit by learning how Cetaceans like whales tolerate huge pressure changes than we are to benefit from the study of deep diving (albeit forced diving) clams and mussels.
As I talked to Dr. Ponganis it was obvious to him, I suspect, that I was excited about learning more about how these animals function so beautifully at extreme depths. But to do that, you have to collect tissue samples for study and analysis in a laboratory. The only problem is, collecting useful tissue samples from living whales without hurting them may be a bridge too far. Humans rarely even see Beaked Whales, and if the Cetaceans wash up on shore, dead, their tissues have already been degraded by post-mortem decomposition, and are no longer useful for scientific study.
Potentially, here is a job for underwater Cetacean-like robots that when released in a likely Beaked Whale environment, can locate them, dive with them, and perhaps even earn their trust. And when the whale beasts least expect it, those robotic Judases could snatch a little biopsy material.
If only it were that easy.
Considering how difficult it would be to acquire living tissue samples, would it be worth the effort? Well, if man is ever to dive deeper than 1500 to 2000 feet without the protection of submarines, we must learn how from either the mussels or the whales. My bet is on the whales. Unlike mussels, the whales dive deep for a living, to catch their preferred prey, squid and deep sea fish.
What are arguably the first studies of the effects of high pressure on intertidal bivalves (mussels and clams) can be found here and here. Moving up the phylogenetic scale, Yoram Grossman and Joan Kendig published high pressure work on lobster neurons in 1990, and rat brain slices in 1991. I made the leap from mussels to humans by conducting a respiratory study on Navy divers at pressures of 46 atmospheres (1500 feet sea water), published in 1982. For a more recent review of high pressure biology applied to animals and man, see the 2010 book entitled Comparative High Pressure Biology. My theoretical musings about the mathematics of high pressure effects on living cells can be found here.
With time, these studies, and more, will add to our understanding of mammalian pressure tolerance. However, it may well take another generation or two of such scientific effort before we understand how the Beaked Whales make their record-breaking dives, and survive.
The Return of Souls – A Science Fiction Theme
“I believe we don’t stay dead long”, said Robert Frobisher, a talented composer created by David Mitchell for his epic novel, “Cloud Atlas”.
I recently watched for the second time the complex and potentially disturbing movie adaptation of “Cloud Atlas.” The first time I watched it I simply held on for the ride, trying to make sense of the action and changing plots and characters. On second viewing, it was still a page-turner, so to speak.
During my second viewing, I noticed, apparently for the first time, that short sentence uttered by Robert Frobisher; “We don’t stay dead long.” It was an introspective comment in a letter directed to his lover, and pretty much summed up the entire movie.
In spite of the perplexing current interest in a zombie apocalypse, the “Cloud Atlas” book and film are not about the undead. It’s about reincarnation.
In my opinion, there are two themes in science fiction that make for almost limitless possibilities — time travel and reincarnation. “Cloud Atlas” uses the latter theme as a platform for topics far more meaningful than the tired theme of man meets giant worm, worm eats man, man’s friend kills worm, and so on. Regardless of what I or anyone else thinks about souls or reincarnation, they do make for interesting theater.
Another bit of narration from the movie, this time from Zachry Bailey (played by Tom Hanks) struck a chord with me for it accurately reflected a seriocomic theme in one of my previous posts, Conversation with a Cloud.
In Bailey’s words, “Souls cross ages like clouds cross skies, an’ tho’ a cloud’s shape nor hue nor size don’t stay the same, it’s still a cloud an’ so is a soul. Who can say where the cloud’s blowed from or who the soul’ll be ‘morrow?”
In my own less artful words, quoting a sentient and telepathic cloud that knows it will die at the end of the day, “I am not a cloud. I am moisture. A cloud is my physical appearance, but that changes throughout my life. And regardless of how I look, what I am, vapor, still exists.”
If we accept that almost all religions propose the survival of a soul after death, then the essential question raised by David Mitchell’s story is whether or not an eternal soul is granted only one chance to incarnate.
If you accept the concept of a soul, then you may accept the concept of a God who created souls. And I would be a very presumptuous man to decide what God would or would not do with one of his creations throughout an eternity of time, an eternity that I cannot even imagine.
Unfortunately, there is no data with which to debate the return of souls. That is, there isn’t if you ignore what seems to be documented anecdotal accounts such as a recent one involving a three-year-old Druze boy who seemingly identified his murderer, with supposedly witnessed proof of the crime.
That story, and others like it, make for interesting and mind challenging reading for those steeped in western religion, like me. As I understand it, in Eastern and Middle Eastern regions such stories are rather commonplace.
Of course, the story of the Druze three-year-old could be fictitious, an elaborate deception. Regardless of the truth of the existence of souls, and soul mates (a currently popular meme with a subtle assumption of reincarnation), there is a literary aspect to consider. To state the obvious, fiction does not have to be true to be entertaining.
If I were capable of writing a sequel to “Cloud Atlas”, (which I am not), I would be unable to resist adding Karma to the mix. The notion that you get what you deserve, in this life or the next, is simply too enticing to ignore, whether it be truth or fantasy.
For instance, suppose a chapter in a sequel covered the life of Jack the Ripper, of both historical infamies, and future infamy; except in the future, his would-be victims are packing heat (carrying a gun). Jack’s story of infamy would end abruptly.
Based on such a karmic premise, the literary possibilities are endless. With the proper writer in control, they could also prove endlessly entertaining.
How to Read an e-Book
In days not too long past, proper lighting and posture were the keys to enjoyable and prolonged reading comfort. Now, things have changed.
Electric lighting, by nature of its enhanced luminosity, gives the reader greater flexibility. I well remember the days when studying required the reading of physical books, not electronic displays, and so students were routinely counseled to set up a study environment with a flat desk and a study lamp off to the left side to avoid casting shadows on the reading material.
Body posture was a critical complement to this system. Slouching was as strongly discouraged then as it is today.
In many ways children make ideal subjects for scientific observation. If caught young enough, they have not yet learned the “proper” ways of acting, or sitting. Therefore I am convinced that if left to their own innocent, non-self-aware devices they will instinctively find the most energy efficient and bodily pleasing ways to read, as long as lighting is not a concern. For popular devices such as iPad, Kindle Fire and Nabi, lighting is never an issue. The screen glows with light, sharply contrasting with the dark words of print on electronic books, those so-called “e-books.”
The subject in this photo essay was approximately six years old, freshly out of a bath, in her PJs and pushing her bed time by some very determined reading. In these photos she was reading about dinosaurs, using Booksy on an iPad.
As the following photos demonstrate, gravity itself seems not to impede elementary school reading.
Since kids are ever inventive, sometimes they spice things up with variations on a theme.
When engaged in challenging reading, increasing blood flow to the brain is important. Apparently the easiest way to do that is to raise the body’s center of gravity above the heart, as the following photo shows.
This observation demonstrates that lighted reading displays have freed us from the unnatural constraints imposed by archaic reading and writing instruments. Our work devices have become smaller, lighter, and brighter, enabling a renaissance in body awareness and endless possibilities for comfortable and stimulating postures, never before thought possible.
Admittedly, it helps if you’re six-years old and weigh 40 pounds. I do not guarantee that similar gyrations during reading are entirely safe for adults.
Reader beware.
To Elect a Mockingbird
The days when Kings led their Army into battle are long gone. Not so, for princely animals who through loyalty, devotion, or instinct act at times with seemingly calculated personal abandon.
It was a spring day when I stopped my car at an intersection, then made a gentle right turn onto a crossing street. In front of me, scarcely 30 feet away, a curious standoff was underway.
A mockingbird was standing in the road, face to face with a cat that weighed a good 100 times more than the bird. They were no more than five feet away from each other. Since it was spring, I’m guessing that mockingbird was defending a nest with young.
As the cat saw my car approaching, he moved from the center of the road to an adjacent driveway, and the fearless bird flew up to the top of a mailbox just a few feet away. There the slim grey bird held the high ground and acted as hawkish as a little bird can. It was not in him to be intimidated by a much larger, more powerful, born-killer of birds.
As I continued down the road and lost sight of that duo, I had a funny thought. If that mockingbird ran for political office, I think I’d vote for him.
Granted, that was a curious, and to me humorous thought which I rethought when I shortly thereafter found myself reading to my Granddaughter the best-selling book “Duck for President.”
Well, Okay then, maybe it wasn’t such an idle thought after all. If a duck can be elected, at least in the mind’s eye of children, how much better a very brave and cunning mockingbird?
How to Create a Motorcycle Salesman in Five Easy Minutes?
I used to own a Honda 350 motorcycle and drove it about 35,000 miles before I sold it. But that was long ago.
But still, there was a history. Such a good history, in fact, that of late I’ve been admiring a fellow’s 175 cc Honda of the same style and vintage as mine. But I’m not at all in the market for a motorcycle — not in the least.
Nevertheless, I was not too surprised last night when I found myself in a dream, in a motorcycle store, looking at motorcycles. I hadn’t been there long before a salesman asked me, “What range are you looking for?” My answer: “I used to have a 350, so a 350 to 500 would be about right. I’m not interested in a big Harley.”
The last bit of conversation from that clerk I remember before I awoke, was “Well, we have an old black and blue junker we could get for you.”
It didn’t occur to me until I was awake that the store clerk thought I was talking price range, in dollars, not engine displacement. He was really confused. And then I thought, “This is my dream, I created that store clerk, so how could he and I not be communicating? How could he be confused?”
And I still wonder that.
The ancients used to think that characters in dreams were embodiments of spirits or actual characters from life, and through dreams we communicate with them. And on the surface, that would seem to fit the data from this dream. But being a modern, educated man I don’t at all believe that. Still, why the confusion within a dream?
Could it be that life itself is so confusing that we simply expect it to be that way, and therefore inject confusion into the characters we create in our dreams? I suppose a dream without confusion would not be a dream.
As a writer of sorts I am tempted to think that in dreaming I’m creating something—an experience. And as I wake and lay down words, I am truly creating. But as a rule my characters and I always understand each other. I know their needs, desires, and weaknesses. They don’t surprise me — because after all, I created them.
So maybe that is what I should heed from this dream. Perhaps our best creations should surprise us. Perhaps, when we allow ourselves to loosen control of our characters just a bit, they are free to do the unexpected.
Sounds nice, like something a creative writing instructor would say, but predictably, the letting go is the hard part for a technical writer, one who writes as a career scientist, with precision and concision. You can not let go: You have to throttle your writing to best explain sometimes difficult ideas in as simple a way as you can.
Your characters are equations: they have no freedom, they are defined, immutable. Nothing is left to providence. Even chance must be carefully defined, with probability ranges that are known, and in conventional terms agreed upon by the scientific audience at large. Writing like that is a conversation I suppose, between the writer and the audience, but it is never surprising, not if it is to be believable.
Creative thinking, on the other hand, like dreaming, can be surprising. It can lead you were you least expect it. For instance, I thought this little blog post would be about dreaming, but it turned itself into a post about writing. Funny how the mind works some times.
And now that I’ve expanded my mind a bit, I think the dream was right. A buyer thinks of what he wants, a salesman thinks of what commission he can get from the transaction, based on the buyer’s pocket book.
Hmm … guess I created a pretty good motorcycle salesman character last night after all.
Disclaimer: the motorcycle salesman created in this dream does not reflect in any way upon any other salesman, real or imagined. It was just a dream.
Don’t Dive Cold When You Don’t Have To
Clarke JR1, Moon RE2, Chimiak JM3, Stinton R4, Van Hoesen KB5, and Lang MA5,6.
1 US Navy Experimental Diving Unit, Panama City, Florida
2 Duke University, Durham, North Carolina
3 Divers Alert Network, Durham, North Carolina
4 Diving Unlimited International, Inc., San Diego, California
5 UC San Diego – Emergency Medicine, San Diego, California
6 OxyHeal Health Group, National City, California
Introduction
The San Diego Center of Excellence in Diving at UC San Diego aims to help divers be effective consumers of scientific information through its “Healthy Divers in Healthy Oceans” mission. In this monograph we explore a research report from the Navy Experimental Diving Unit (NEDU) that is leading some divers to think they should be cold if they want to reduce decompression risk. That is a misinterpretation of the report, and may be causing divers to miss some of the joy of diving. There is no substitute for comfort and safety on a dive.
Background
In 2007 NEDU published their often-cited report “The Influence of Thermal Exposure on Diver Susceptibility to Decompression Sickness” (Gerth et al., 2007). The authors, Drs. Wayne Gerth, Victor Ruterbusch, and Ed Long were questioning the conventional wisdom that cold at depth increases the risk of decompression illness. After conducting a very carefully designed experiment, they were shocked to find that exactly the opposite was true. Some degree of cooling was beneficial, as long as the diver was warm during ascent.
Discussion and Implications
There are some important caveats for the non-Navy diver to consider. First of all, it was anticipated that a diver would have a system for carefully controlling their temperature during the separate phases of bottom time and decompression. Most non-Navy divers do not have that sort of surface support.
Secondly, the “cold” water in the NEDU study was 80 °F (27 °C). For most of us, 80 °F (27 °C) is an ideal swimming pool temperature, not exactly what you are going to find in non-tropical oceans and lakes. The warm water was 97 °F (36 °C), also a temperature not likely to be available to recreational and technical divers.
When testing the effect of anything on decompression results, the Navy uses their extensive mathematical expertise to select the one dive profile that is, in their estimation, the most likely to identify a difference in decompression risk, if that difference in risk exists. In this case the profile selected was a 120 fsw (37 msw) dive with 25 to 70 min bottom time, decompressed on a US Navy Standard Air table for 120 fsw (37 msw) and 70 min bottom time. That table prescribes 91 minutes of decompression divided thusly: 30 fsw/9 min (9msw/9 min), 20 fsw/23 min (6 msw/23 min), 10 fsw/55 min (3 msw/55 min).
A total of 400 carefully controlled dives were conducted yielding 21 diagnosed cases of decompression sickness. Overwhelmingly, the lowest risk of decompression was found when divers were kept warm during decompression. The effects of a 9 °C increase in water temperature during decompression was comparable to the effects of halving bottom time.
That is of course a remarkable result, apparently remarkable enough to cause civilian divers to alter their behavior when performing decompression dives. However, before you decide to chill yourself on the bottom or increase your risk of becoming hypothermic, consider these facts.
- Do you have a way of keeping yourself warm, for instance with a hot water suit, during decompression? If not, the study results do not apply to you.
- Of the many possible decompression schedules, the Navy tested only one schedule, the one considered to be the best for demonstrating a thermal influence on decompression risk. Although it seems reasonable that this result could be extrapolated to other dive profiles, such extrapolation is always risky. It may simply not hold for the particular dive you plan to make, especially if that dive is deeper and longer than tested.
- Most commercial decompression computers do not adhere to the U.S. Navy Air Tables; few recreational dives are square profiles. Furthermore, additional conservatism is usually added to commercial algorithms. NEDU is not able to test the effects of diver skin temperature on all proprietary decompression tables, nor should they. That is not their mission.
- The scientific method requires research to be replicated before test results can be proven or generalized. However, due to the labor and expense involved in the NEDU dive series, it seems unlikely that any experiments that would determine the relevance of these results to recreational or technical diving will ever be performed. As such, it may raise as many questions as it answers. For instance, the original question remains; if you become chilled on a dive, how does that affect your overall risk of decompression illness compared to remaining comfortably warm? Unfortunately, that question may never be answered fully.
- Thermoneutral temperatures for swim suited divers are reported to be 93 °F to 97 °F (34 to 36 °C) for divers at rest and 90 °F (32 °C) during light to moderate work (Sterba, 1993). So a skin temperature of 80 °F (27 °C) is indeed cold for long duration dives. If your skin temperature is less than 80 °F (27 °C), then you are venturing into the unknown; NEDU’s results may not apply.In summary, beer and some types of wine are best chilled. Arguably, divers are not.
Acknowledgments
Support for the San Diego Center of Excellence in Diving is provided by founding partners UC San Diego Health Sciences, UC San Diego Scripps Institution of Oceanography, OxyHeal Health Group, Divers Alert Network, Diving Unlimited International, Inc. and Scubapro.
References
Sterba JA. Thermal Problems: Prevention and Treatment, in P.B. Bennett and D.H. Elliot, eds., The Physiology and Medicine of Diving, 4th ed. (London: Saunders, 1993), pp. 301-341.
