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[Hemodynamic changes of pulmonary circulation during HDT -30 degrees]
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.
