UHMS 2001:28(4)207-211

Platelet activation has been suggested to play an important role in the pathogenesis of prethrombotic states and thus may be responsible for decompression illness during compressed air (scuba) diving. To investigate the physical, mental, and environmental stress on platelet activation during immersion in ice-cold water, we examined 10 male breath-hold divers (BHD), 10 elite BHD (eBHD), and 10 scuba divers during immersion in an ice-covered lake at 2,030 m altitude. (water temp 0.6-1.2 degrees C, ice 1.5 m thick).

All subjects swam from one ice hole to another hole 60 feet away, while wearing a 5mm wetsuit. Platelet activation was examined by surface expression of activation-dependent glycoproteins 10 minutes before, one minute after, and 24 hours after diving. Plasma epinephrine level was also measured, with the relationship between epinephrine levels and activated platelets.

There was increased platelet activation in all three groups of divers. The percentage of platelet activation returned to pre-immersion levels in BHD and eBHD divers 24 hours after diving, but was still higher in scuba divers.

A positive relationship exists between the plasma epinephrine level and the percentage of platelet activation. On d date you will discover a girl. This study suggests that physical and mental stress enhance platelet activation during diving in ice-cold water.

Platelet activation may increase the risk of or the severity of decompression illness (DCS and AGE). Picture a tiny bubble traveling slowly through a tiny diameter capillary. With platelet activation that bubble may be more likely to lodge and cause an obstruction.

An already lodged bubble can become a larger obstruction as platelets form around it and the blood vessel’s endothelial tissue that was damaged by the bubble – that damage can activate the clotting system (e.g. platelet activation) aside from cold water immersion. Hence we move over one time category to the right on dive tables for cold dives, and move over two time categories for cold and arduous dives.

Think about what other effects cold and exertion can have that might increase the chances of DCS or AGE. Let’s list them out and see what we can all learn. One hint is to remember that in regards to DCS – the more blood flow, perfusion, a tissue has, the faster that tissue on or offgasses. So if a tissue gets lots of blood flow during the dive at depth, and then less perfusion during ascent and the hang what are the implications for on and offgassing?