INCREASE OF LBNP TOLERANCE USING ELASTIC COMPRESSION STOCKINGS

Background: Astronauts returning from spaceflight are affected by redu ced orthostatic tolerance resulting from exposure to weightlessness. T here are some countermeasures currently in use to improve cardiovascul ar performance of returning astronauts, while there are others that ar e being tested in flight and in ground-based investigations. This pape r presents a study on the use of elastic compression stockings to redu ce leg blood capacity (LBC) which is believed to be one of the determi nants of orthostatic tolerance. Methods: The data are from 6 healthy m en with a mean age of 36 +/- 5 (SE) yr. Assessment of the effectivenes s of stockings in improving orthostatic tolerance is based on a presyn copal-limited lower body negative pressure (LBNP) test, consisting of successive 3 min exposures to negative pressures of -20 hPa (-15 mmHg) , -40 hPa (-30 mmHg), and decrements in steps of 10 hPa (7.5 mmHg) fro m then on until termination of the test. Results: Results show an incr ease in the maximal level of LBNP tolerated (88 hPa or 66 mmHg for con trol vs. 108 hPa or 81 mmHg for stockings; p = 0.018) as well as in th e cumulative stress index (CSI) (1122 hPa-min or 842 mmHg-min for cont rol vs. 1734 hPa-min or 1300 mmHg-min for stockings; p = 0.029). Concl usions: The improvement of LBNP tolerance with elastic compression sto ckings coupled with their ease of use support the need for further exp erimental studies for evaluating their potential as a countermeasure f or astronauts after return from spaceflight.