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> > everyone has bubbles after a dysbaric exposure > There is no evidence for bubbles after every decompression. It may be that we don't yet have instrumentation to find bubbles that are there. More likely, not all decompressions are sufficient - ascending in elevators for one example, many diving scenarios as another. There's no demonstrated reason for bubbles after all exposures. John Crea's masterful post on complement reminded me of a Peanut's cartoon. Lucy asks Linus what he sees in the clouds they are both lying on their backs observing. Linus produces a literary and social exposition of the great historical figures he sees, their comparison in social analogy to contemporary events, and so on. Lucy then asks Charlie Brown who responds "I was going to say I saw a duckie and a horsie, but I changed my mind". With that in mind I'll just add: Complement is a cascade of immune reactions in response to foreign entities like bacteria, viruses and decompression bubbles. Involves at least 20 different blood serum proteins and two different pathways. Complement proteins combine with antibodies to destroy foreign invaders. Less commonly the complement is called alexin, from a Greek word meaning 'to ward off'. Consequence of the complement cascade to diving and microbubbles remains unknown. > If someone is going to go to the trouble of Dopplering (is that a > word?) a group of divers and grading their Doppler sounds and > writing a Neural Net program to analyse the sounds... We Doppler (have Dopplered, are Dopplering...) and are conducting work to automate the scoring, not by neural net, but signal processing - separating bubble events from non-events - a challenge. > folklore names for DCI -- I believe it's called "taravu" by one south > pacific group. Taravu is roughly translated as "the madness". > Taravana - DCS among the south sea breath hold pearl divers more or less means 'to fall crazily'. Humans dive after near maximal inspiration - nitrogen from the lungs dissolves in blood. One way certain diving sea mammals escape DCS is to dive after exhalation. > average persons total lung capacity is about 6 liters. Hence a free > diver may descend to 4 ATA or 99 fsw before his lungs are > compressed to the residual volume (6/1.5 = 4). Luckily we are not machines according to rules of physics, but self adjusting (homeostatic) living things according to physiology. Blood, fluids, are pulled into the chest area by decreasing lung size to form a liquid (incompressible) area. Prevents ambient pressure from decreasing lung size below residual. > Next you will be telling us that the ultrasonic waves from the > Doppler device will cause cavitation and bubble formation in the > cerebral circulation, ie, Doppler testing always finds bubbles > becasue it causes bubbles! Sound and ultrasonic energy have been looked at. Harvey (1955) showed bubble formation rate can be accelerated by ultrasonic energy. He fired a bullet into the side of a water tank creating local pressure changes associated with the shock and sound waves. When each positive pressure field reflected from a surface, it became a negative wave which formed bubbles behind it. The driving force in gas phase production is the difference between the dissolved gas partial pressure, and the absolute pressure (Px - Pabs). Shilling et al. (1976) showed local fluid pressure is substantially reduced as the amplitude of the ultrasonic pressure wave increases, and that the negative wave creates bubbles faster than the positive wave dissolves them. However, the Doppler devices used for trying to detect bubbles do not have the energy at their frequency to create or accelerate existing bubble formation.
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