OBJECTIVE: To study the hemodynamic changes of pulmonary circulation during simulated weightlessness. METHOD: 12 subjects were studied using echocardiography and electrocardiography during head-down tilt (HDT) of -30 degrees lasting for 45 min. RESULT: Right ventricular ejection time increased significantly (P<0.05); peak velocity of pulmonary arterial blood flow decreased significantly (P<0.05); acceleration time of pulmonary arterial blood flow did not change significantly; significant decrease of right ventricular output occurred at the 10th minute and the 30th minute (P<0.05); pre-ejection period significantly decreased at the 30th minute and recovery. Heart rate, mean velocity of pulmonary arterial blood flow, and acceleration of pulmonary arterial blood flow did not change significantly; left ventricular cardiac output, stroke volume and blood pressure remained constant throughout the experiment. CONCLUSION: Changes of the parameters of pulmonary circulation suggested that pulmonary resistance increased, and the increase of pulmonary resistance maybe be the direct cause of the increase of pulmonary arterial pressure.
OBJECTIVE: To study the hemodynamic changes of pulmonary circulation during simulated weightlessness. METHOD: 12 subjects were studied using echocardiography and electrocardiography during head-down tilt (HDT) of -30 degrees lasting for 45 min. RESULT: Right ventricular ejection time increased significantly (P<0.05); peak velocity of pulmonary arterial blood flow decreased significantly (P<0.05); acceleration time of pulmonary arterial blood flow did not change significantly; significant decrease of right ventricular output occurred at the 10th minute and the 30th minute (P<0.05); pre-ejection period significantly decreased at the 30th minute and recovery. Heart rate, mean velocity of pulmonary arterial blood flow, and acceleration of pulmonary arterial blood flow did not change significantly; left ventricular cardiac output, stroke volume and blood pressure remained constant throughout the experiment. CONCLUSION: Changes of the parameters of pulmonary circulation suggested that pulmonary resistance increased, and the increase of pulmonary resistance maybe be the direct cause of the increase of pulmonary arterial pressure.
Authors: A Cortney Henderson; David L Levin; Susan R Hopkins; I Mark Olfert; Richard B Buxton; G Kim Prisk Journal: J Appl Physiol (1985) Date: 2006-04-06