From Tim Walsh
I enjoyed your article on the bends
(13 January, p 9) but I must make one
correction. When divers breathe gas at depth it is dissolved in their blood. If
the ultrasound device measures gas in the blood, which seems reasonable, it will
not measure anything while the gas is in solution. However, as the divers ascend
the gas forms microbubbles. As the divers ascend further the bubbles get larger
until they have the potential to block small capillaries, depriving tissues
downstream of oxygen and killing them.
Presumably the device can warn divers when this unhappy situation is
approaching and they can stop their ascent, wait awhile (assuming that they
still have enough air left to breathe) and then continue ascending when the
bubbles have been filtered out by their lungs.
Bristol
