CALIBRATION OF A BUBBLE EVOLUTION MODEL TO OBSERVED BUBBLE INCIDENCE IN DIVERS

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Authors
  1. Gault, K.A.
  2. Tikuisis, P.
  3. Nishi, R.Y.
Corporate Authors
Defence and Civil Inst of Environmental Medicine, Downsview ONT (CAN);Waterloo Univ, Waterloo ONT (CAN) Dept of Physics
Abstract
The method of maximum likihood was used to calibrate a probabilistic bubble evolution model against data of bubbles detected in divers. These data were obtained from a diverse set of 2,064 chamber man-divers involving air and heliox with and without oxygen decompression. Bubbles were measured with Doppler ultrasound and graded according to the Kisman-Masurel code from which a singble maximum bubble grade (BG) per diver was compared to the maximum bubble radius (Rmax) predicted by the model. This comparison was accomplished using multinomial statistics by relating BG to Rmax through a series of probability functions. The model predicted the formation of the bubble according to the critical radius concept and its evolution was predicted by assuming a linear rate of inert gas exchange across the bubble boundary. Gas exchange between the model compartment and blood was assumed to be perfusion-limited. The most successful calibration of the model was found using a trinomial grouping of BG according to no bubbles, low, and high bubble activity, and by assuming a single tissue compartment. Parameter estimations coverage to a tissue volume of 0.00036 cubic cm, a surface tension of 5.0 dyne (1), respective time constants of 27.9 and 9.3 min for nitrogen and helium, and respective Ostwald tissue solubilities of 0.0438 and 0.0096. TRUNCATED.
Keywords
Prediction models;Bubble grades
Report Number
DCIEM-94-58 — Reprint
Date of publication
01 Jan 1995
Number of Pages
14
Reprinted from
Undersea Hyperbaric Medicine, vol 22, no 3, 1995, p 249-262
DSTKIM No
96-00389
CANDIS No
154360
Format(s):
Document Image stored on Optical Disk;Hardcopy

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