Effect of Frequent Hypothermia

[FishDiver]

One reason divers in my area dive dry is to prevent prolonged post-dive chilling. One friend recently bought a drysuit because he began to remain chilled 2-3 days after diving. It also occurs to me that DMs invariably wear more exposure protection than recreational divers due to prolonged water immersion.

This all leads to my question. Does frequent, mild hypothermia have any long-term negative physiological effects for divers?

 

[DavidPT40]

It is hypothesized that people with anorexia grow many fine body hairs due to chronic low body temperature. Sort of like the peach fuzz on an adolescent's cheek.

 

[cutlass]

I don't know the prevalance but there is an acquirable condition called "cold urticaria" which means having an allergic reaction -- usually like hives -- to cold. I know a surfer who has it; he's bummed.

 

[DocVikingo]

One reason divers in my area dive dry is to prevent prolonged post-dive chilling. ... This all leads to my question. Does frequent, mild hypothermia have any long-term negative physiological effects for divers?

Hi FishDiver,

Mild hypothermia typically is defined as a core body temperature of 90–95°F/32–35°C. Except in unusual circumstances, an internal body temperature measurement generally is not made.

A working diagnoses of mild hypothermia can be made on the basis of some combination of mild shivering, cyanosis, incoordination, confusion/difficulty in thinking, drowsiness, reduced energy, and changes in respiratory rate.

Repeated episodes of clinical hypothermia can result in various organ system abnormalities, including pneumonia, pancreatitis, kidney failure, cardiac arrhythmia and coagulopathy. However, frequent, mild hypothermia-like events in an otherwise healthy diver likely do not have any signifcant long-term negative physiological effect.

Nevertheless, it appears unusual that an otherwise healthy diver would continue "to remain chilled 2-3 days after diving." It might be prudent for an individual with this complaint to be medically evaluated. Such a work up should include assessment of thyroid functioning and glucose metabolism as well as a review of medications taken as certain antihypertensives, antidepressants, tranquilizers, sedatives, narcotics and other meds can reduce the body's response to low temperatures. BTW, alcohol before or after SCUBA is unwise, especially in an individual prone to easy chilling.

Regards,

DocVikingo

This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual and should not be construed as such.

 

[herman]

Caused acute pain in my wallet a time or 2...dry suit gear is expensive.

 

[Akimbo]

... Does frequent, mild hypothermia have any long-term negative physiological effects for divers?

A study was done in the UK in the late 1960s or early 70s that showed that Navy divers fathered an unusually high percentage of baby girls. One theory was that cold water killed the less hardy male sperm. I will leave it to people wiser (or braver) than me to judge if this is a negative effect or not. It would be interesting to know if these stats are true now that dry and hot water suits are prevalent.

 

[DocVikingo]

I don't know the prevalance but there is an acquirable condition called "cold urticaria" which means having an allergic reaction --

Hi Cutlass,

To the best of my admittedly limited knowledge, the prevalence of acquired primary cold urticaria is not at all well defined, but it is fairly solid that it's relatively uncommon. Mean age of onset varies by study, but appears to be ~25 years (with a phenomenal range). It is more frequent in females than males.

Of interest is that, unlike some hypersensitivity reactions, acquired cold urticaria does not appear subject to progressive worsening/sensitization by repeated exposures to cold. In fact, one method of management is the cautious induction of cold tolerance by gradually exposing the skin to cold and then continuing to do on a regular basis such as by daily cold showers.

Regards,

DocVikingo

 

[DocVikingo]

A study was done in the UK in the late 1960s or early 70s that showed that Navy divers fathered an unusually high percentage of baby girls. One theory was that cold water killed the less hardy male sperm.

Hi Akimbo,

The findings of that study were discredited many years ago. There is no compelling evidence for such a link.

Regards,

DocVikingo

 

[Akimbo]

Hi Akimbo,

The findings of that study were discredited many years ago. There is no compelling evidence for such a link.

Regards,

DocVikingo

Interesting, are you sure? What I read (like 40 years ago) is the media got hold of the story where it quickly morphed from a report to a medical study, then into just Navy divers (implying US Navy), and then just to divers (implying all). Of course that was discredited. The actual report I am aware of was on British Navy divers who were active in the 1950s and 60s. Me and my girlfriend were really interested at the time since I was around 19 and just started Navy Diving School.

To the best of my knowledge, a formal study was not performed on US Navy divers. However, somebody at EDU (Experimental Diving Unit) may well have crunched some numbers on a limited group and figured it wasn’t worth pursuing — keep in mind all records were not so computerized then so it would have been a big-budget task to do Navy-wide. In fact, I am pretty sure the report was only on Royal Navy (RN) divers and didn’t compare it to the RN population or even the UK’s, only to industrialized nations.

I recall informal conversations with the Navy hyperbaric docs aboard the diving system I was on. They had copies of the actual report from RN. I forget the exact numbers, but average birth rates in industrialized nations favor males by some small percentage around 1-5%. They were reversed according to the report. It is not like it was some huge discrepancy like 25%. It is difficult to believe the study itself was statistically that incorrect since the data was from RN records and only addresses the statistical anomaly. Drawing conclusions from the report would be totally bogus since the population of RN divers was so small and the time period is so short.

My impression from the Ex-Brit Navy divers I worked with in the North Sea during the mid-70s was the RN was far less protective of their divers regarding hyperthermia than the USN — of course they have a much greater percentage of cold water to work in. I am not drawing a conclusion, only making an observation.

I probably have not thought about this in 35 years. Please don’t take this reply as argumentative, I really do find the whole thing fascinating from the physiology to the impact of lazy media reporting.

 

[DocVikingo]

Interesting, are you sure?I probably have not thought about this in 35 years. Please don’t take this reply as argumentative, I really do find the whole thing fascinating from the physiology to the impact of lazy media reporting.

Hey Akimbo,

I certainly do not take your reply as argumentative. Informed, sober, courteous discussion and debate are always welcome in response to my posts. Not to mention that this topic is ever so much more titillating than are packing divers with DCI in ice and microbubble variability ; )

For all you ever wanted to know (and more) about the effects of military service on spermatogenesis, see: "The effects of military service on spermatogenesis" (http://www.defence.gov.au/health/infocentre/journals/adfhj_sep01/ADFHealthSep01_2_2_71-74.pdf).

I believe the particular study to which you may be referring is an unpublished work by the avuncular and world-reknown diving medicine expert Dr. Carl Edmonds. I believe it involved military divers active in the 50s & 60s. In any event, it definitely addresses the issue at hand.

On pages 72-73 of that article you'll read: "Diving and fertility Few areas of military activity seem to generate as much myth and legend as diving. It is a common belief that male divers’ offspring tend to be female, and the mechanism for this is often quoted as a hyperbaric effect on testicular perfusion. In an unpublished study, Edmonds conducted a retrospective review of Royal Australian Navy divers’ offspring. Of 240 offspring, 122 were conceived before diving activities, the remaining 118 after the divers received their diving qualifications. Edmonds further divided these groups into air divers and oxygen divers, and generated 2×2 contingency tables that were analysed by χ2 test. There was no significant difference between the groups and no support for the hypothesis that divers have a propensity to female offspring (Edmonds, quoted by Commander Robyn Walker, personal communication)."

Responsive?

Regards,

DocVikingo