[Effect of 7 d head down bed rest on cardiopulmonary circulation in human]

Changes of cardiopulmonary circulation in 6 healthy young men during 7 d head down bed rest (-6 degrees HDT) were observed with the XXH-2000 lesser circulation and cardiac function instrument. Decrease of Q-j and Q-j/j-z, increase of hz, hc, and hc/hz were found during the initial 24 h. After 24 h, j-z decreased and Q-j/j-z increased. The results showed that increased pulmonary arterial pressure, increased preload of left and right heart, increased right myocardial contractility and congestion of the lungs appeared during 24 h bed rest, after which right myocardial contractility decreased. It suggests that the lesser circulation and cardiac function testing is a sensitive method for evaluating the cardiopulmonary circulation function during HDT.