title: [Effects of 7 d head down tilt on cardiopulmonary circulation during orthostasis].
abstract: Objective. To accumulate data for further studies on the mechanisms of the decrease of cardiovascular function after weightlessness. Method. Cardiopulmonary circulatory function under supine position and head up tilting (HUT) for 20 min before and after exposure to 7 d 6 degrees head down tilt (HDT) in 6 healthy adults who aged 19-21 were measured with a XXH-2000 lesser (pulmonary) circulation and cardiac function instrument. Result. The 7 d HDT resulted in orthostatic intolerance of the subjects; the reduction of RVET (j-z) and the elevation of RPEP [RVET(Q-j)/(j - z)] indicated a decrease of the right heart function. An obvious decrease of the right heart reserves was also observed under HUT after HDT. Conclusion. hc and hc/hz were demonstrated to be useful parameters to evaluate orthostatic tolerance or to forecast orthostatic syncope. The lesser (pulmonary) circulation and cardiac function testing methods are valuable in evaluating the cardiopulmonary circulatory function during HUT.
authors.affiliation: Institute of Space Medico-Engineering, Beijing, China.
authors.forename: D S
authors.initials: DS
authors.lastname: Wang
authors.forename: Q L
authors.initials: QL
authors.lastname: Xiang
authors.forename: X Y
authors.initials: XY
authors.lastname: Shen
authors.forename: J R
authors.initials: JR
authors.lastname: Meng
authors.forename: Q
authors.initials: Q
authors.lastname: Dong
mesh_terms: D000328:Adult; D000337:Aerospace Medicine; D001510:Bed Rest; D018493:Cardiovascular Deconditioning / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D018475:Head-Down Tilt / Q000009:adverse effects* / Q000502:physiology; D006801:Humans; D007024:Hypotension, Orthostatic / Q000209:etiology / Q000503:physiopathology*; D011187:Posture / Q000502:physiology*; D011652:Pulmonary Circulation / Q000502:physiology*; D016683:Supine Position / Q000502:physiology; D013575:Syncope / Q000209:etiology / Q000503:physiopathology; D018474:Weightlessness Simulation / Q000009:adverse effects