Accession Number : ADA302972

Title :   Cardiovascular Responses to Very Long Duration Positive Pressure Breathing.

Descriptive Note : Final rept. Jan 93-Sep 94,

Corporate Author : DEFENCE AND CIVIL INST OF ENVIRONMENTAL MEDICINE DOWNSVIEW (ONTARIO)

Personal Author(s) : Fraser, W. D. ; Ackles, K. N.

PDF Url : ADA302972

Report Date : MAR 1995

Pagination or Media Count : 72

Abstract : This study was undertaken to examine the effectiveness of the US Navy Enhanced Anti-G Lower Ensemble (EAGLE) and the US Air Force Advanced Tactical Anti-G System (ATAGS) enhanced coverage G-suits in providing protection against the adverse effects of positive pressure breathing and to establish the physiological duration limits of high levels of PPB. Six experienced subjects, wearing ATAGS and EAGLE G-suits and counter pressure chest jerkins, were exposed to counterbalanced sessions of 60, 70, and 80 mmHG PPB for up to 20 minutes. They underwent an additional exposure at 70 mmHG PPB while wearing the Tactical Life Support System (TLSS) integrated G-suit and PPB jerkin. G-suit pressure was 4 times PPB jerkin and mask pressure. All six subjects completed 80 mmHG PPB. Five of the subjects completed the 60 mmHG session and four of the subjects completed the 70 and 80 mmHG PPB session with the EAGLE garment. There were small, but statistically significant differences, in the changes in heart rate, stroke volume, cardiac index, and mean arterial blood pressure among the three garments with the TLSS garment providing better overall cardiovascular support at 70 mmHG PPB. The ability of some subjects to tolerate 80 mmHG of PPB for up to 20 minutes without difficulty indicates that the duration limit for this type of PPB exposure, with respect to either cardiovascular collapse or discomfort, has yet to be established.

Descriptors :   *G SUITS, *RESPONSE(BIOLOGY), *LIFE SUPPORT SYSTEMS, *CARDIOVASCULAR SYSTEM, *PRESSURE BREATHING, VOLUME, INTEGRATED SYSTEMS, TIME, LIMITATIONS, PRESSURE, ADVERSE CONDITIONS, PHYSIOLOGY, INDEXES, MEAN, CLOTHING, HEART RATE, HEART, MASKS, BLOOD PRESSURE, CARDIOVASCULAR DISEASES.

Subject Categories : Anatomy and Physiology
      Life Support Systems

Distribution Statement : APPROVED FOR PUBLIC RELEASE