Journal of Applied Physiology, Vol 69, Issue 3 914-918, Copyright © 1990 by American Physiological Society

ARTICLES

Human dose-response relationship for decompression and endogenous bubble formation

R. G. Eckenhoff, C. S. Olstad and G. Carrod
Department of Anesthesia, University of Pennsylvania Medical Center, Philadelphia 19104-6068.

The dose-response relationship for decompression magnitude and venous gas emboli (VGE) formation in humans was examined. Pressure exposures of 138, 150, and 164 kPa (12, 16, and 20.5 ft of seawater gauge pressure) were conducted in an underwater habitat for 48 h. The 111 human male volunteer subjects then ascended directly to the surface in less than 5 min and were monitored for VGE with a continuous-wave Doppler ultrasound device over the precordium or the subclavian veins at regular intervals for a 24-h period. No signs or symptoms consistent with decompression sickness occurred. However, a large incidence of VGE detection was noted. These data were combined with those from our previously reported experiments at higher pressures, and the data were fit to a Hill dose-response equation with nonlinear least-squares or maximum likelihood routines. Highly significant fits of precordial VGE incidences were obtained with the Hill equation (saturation depth pressure at which there is a 50% probability of detectable VGE [D(VGE)50] = 150 +/- 1.2 kPa). Subclavian monitoring increased the sensitivity of VGE detection and resulted in a leftward shift [D(VGE)50 = 135 +/- 2 kPa] of the best-fit curve. We conclude that the reduction in pressure necessary to produce bubbles in humans is much less than was previously thought; 50% of humans can be expected to generate endogenous bubbles after decompression from a steady-state pressure exposure of only 135 kPa (11 ft of seawater). This may have significant implications for decompression schedule formulation and for altitude exposures that are currently considered benign. These results also imply that endogenous bubbles arise from preexisting gas collections.

This article has been cited by other articles:

				A. O Brubakk, D Duplancic, Z Valic, I Palada, A Obad, D Bakovic, U Wisloff, and Z Dujic A single air dive reduces arterial endothelial function in man J. Physiol., August 1, 2005; 566(3): 901 - 906. [Abstract] [Full Text] [PDF]

				Z. Dujic, D. Duplancic, I. Marinovic-Terzic, D. Bakovic, V. Ivancev, Z. Valic, D. Eterovic, N. M Petri, U. Wisloff, and A. O. Brubakk Aerobic exercise before diving reduces venous gas bubble formation in humans J. Physiol., March 15, 2004; 555(3): 637 - 642. [Abstract] [Full Text] [PDF]

				D. Carturan, A. Boussuges, P. Vanuxem, A. Bar-Hen, H. Burnet, and B. Gardette Ascent rate, age, maximal oxygen uptake, adiposity, and circulating venous bubbles after diving J Appl Physiol, October 1, 2002; 93(4): 1349 - 1356. [Abstract] [Full Text] [PDF]

				S. Skogland, K. Segadal, H. Sundland, and A. Hope Gas bubbles in rats after heliox saturation and different decompression steps and rates J Appl Physiol, June 1, 2002; 92(6): 2633 - 2639. [Abstract] [Full Text] [PDF]

				R. S. Lillo and E. C. Parker Mixed-gas model for predicting decompression sickness in rats J Appl Physiol, December 1, 2000; 89(6): 2107 - 2116. [Abstract] [Full Text] [PDF]

				M. Knauth, S. Ries, S. Pohimann, T. Kerby, M. Forsting, M. Daffertshofer, M. Hennerici, and K. Sartor Cohort study of multiple brain lesions in sport divers: role of a patent foramen ovale BMJ, March 8, 1997; 314(7082): 701 - 701. [Abstract] [Full Text]