Oceans of Opportunity

the bottom line on hypothermia

'A New Life in the Sea' by Michael LombardiThis 2010/2011 winter has been brutally cold here in the Northeast, and unarguably colder than most. As time has passed over the years, it’s become harder and harder to jump in the water this time of year. But, therein lies no choice if one is to continue working as a diving contractor in New England. There is nothing pleasant about it, and all you can do is plan well in advance for the elements.

For the majority of the winter months, say late November through early March, we use hotwater suits when diving with surface-supplied equipment. So, despite the cold air temperatures, once the diver plugs in, he has bath temperature water surrounding his body for the rest of the day. From a comfort perspective, it’s better to be the diver than working topside all winter – though special consideration needs to given to dehydration. Every now and again however, a project comes up where SCUBA is the tool for the job. Requiring the autonomy of SCUBA means sacrificing hotwater, so we use the next best thing – drysuits. While ‘dry’, being warm isn’t always a reality, especially for extended exposures in the water.

A couple of days ago was a somewhat painful reminder of the effects of hypothermia on human performance. I was off the Rhode Island coast conducting a shipboard dive operation for a client who required that an instrument be recovered. Simple task, shallow depth, calm seas, but f-‘ing cold outside. Rubber parts on your equipment become brittle and are at risk of cracking, o-rings are too stiff to adequately seal on regular/cylinder surfaces, and it is an ordeal in and of itself to just suit up on deck. Those are the mechanics – the simple stuff. The hard part is the psychological preparation for jumping in to the water.

And there I was on the stern of the boat, all suited up, and careful not to breathe into my regulator for fear of the condensation from my breathe freezing and causing a fee flow malfunction. The dive supervisor gives us the green light, reg in mouth, and off we go.

Now, I’ve been in colder environments than New England in the winter. I spent a couple of months in Antarctica in 2002 where we made several dives beneath the ice into the 27.4 degree Fahrenheit water.here however, diving is generally staged from heated huts to buffer the discomfort of taking the plunge. Out on a vessel, exposed, you start the day cold, and there’s no relief til it’s all over. This is no place to mess around, as hypothermia can settle in without even realizing the incremental impairment.

Hitting the water, I gasped. The air from my cylinder was freezing cold, and the water wasn’t much better. I breathed hard during the entire dive. The fact that my hands and face were chill-bitten didn’t even register, as I focused on my breathing and keeping a clear head to accomplish the work task. On hitting bottom, I checked my dive computer which registered 31 degrees Fahrenheit…

That was the COLDEST I have ever experienced the water in New England, and must have been an unusual wave of coldwater given that the regional temperature usually doesn’t drop below 36 this time of year. It just plain hurt, and I could clearly recognize the onset hypothermia given my mental state. Clouded judgement, slow reactionary times, and an innate response urge of  flight to the situation which I had to overcome to get the job done. Not good. The day required about one cumulative hour of dive time, and we did get the job done, but with a renewed respect and appreciation for operating underwater under these conditions.

I guess my point is to be careful out there. There is very little room for error when diving in general, and when the environmental conditions drastically reduce the margin, self-awareness and recognition of hypothermia symptoms are critical. Symptoms of mild hypothermia include shivering, hypertension, tachycardia, tachypnea, and vasoconstriction – all of which are physiological responses to preserve heat. The fact that any or all of these might be taking place under a degree of mental confusion (symptom of early onset of MODERATE hypothermia) just complicates the situation and could lead to a cascading series of problems.

Bottom line – please be careful out there this time of year – both above and below the water.

Reference

Hayward, M., & Keatinge, W. (1979). Progressive symptomless hypothermia in water: possible cause of diving accidents. BMJ, 1 (6172), 1182-1182 DOI: 10.1136/bmj.1.6172.1182

Enhanced by Zemanta