Publication Date:
2011-08-26
Description:
Purpose. It is generally accepted that DCS symptoms are caused by gas bubbles in tissues. However, current technology of bubble detection only permits monitoring of circulating bubbles, primarily intracardiac. Since the majority of DCS symptoms appear to be caused by extravascular bubbles, it has been suggested that current bubble detection techniques target bubbles that are of importance in only a minority of DCS cases. The purpose of this study is to determine the relationships between measured VGE and DCS symptoms in human subjects exposed to altitude. Methods. The AFRL DCS Research Database contains records on 2044 subject-exposures to simulated altitudes in a hypobaric chamber. VGE monitoring was accomplished using Doppler/Echo Imaging techniques. The Spencer Scale was used to score the VGE. Reporting of DCS symptoms by the subject was the primary end-point of the exposures. Results: The Mantel- Haenzel test indicated a strong correlation between DCS and bubble grade (p-value =0.001). Conclusions. A positive correlation between increasing VGE scores and DCS symptoms, does not imply causatinn. If all non-zero VGE grades are considered, 45.9% of the cases had VGE, but no DCS symptoms. Conversely, almost 1 in 5 subject-exposures resulted in DCS with NO VGE detected. VGE scores are not . good predictors of altitude DCS symptoms and field use of bubble detection for DCS prevention is not supported by this study.
Keywords:
Aerospace Medicine
Type:
Aviation, Space, and Environmental Medicine; Volume 70; No. 4; 364
Format:
text
