title: Noninvasive assessment of influence of resistant respiration on blood flow velocities across the cardiac valves in humans--a quantification study by echocardiography.
abstract: The aim of our study is to quantitatively investigate influence of the intrathoracic pressure change on the four cardiac valves' velocities and further verify a new proposal of the mechanism of respiratory influence on hemodynamics.
  
  
  METHODS
  Thirty healthy volunteers with no cardiopulmonary diseases were included. The intrathoracic pressure changes were measured with self-designed device. The velocity across the four cardiac valves during spontaneous respiration and with the intrathoracic pressure change at -4, -8, and -12 mmHg, respectively, were recorded simultaneously with the electrocardiogram and respiratory curve. The respiratory variation indices (RVIs) were calculated. The average RVIs of mitral, aortic, tricuspid, and pulmonary valves were 12.54%, 13.19%; 6.23%, 8.27%; 20.27%, 24.36%; and 6.45%, 7.69% with intrathoracic pressure change at -8 mmHg and -12 mmHg, respectively. All the above parameters have a significant difference from those during spontaneous respiration (P < 0.01 or P < 0.001). We concluded that it might be the respiratory intrathoracic pressure change that causes the change of the velocity across the valves.
authors.affiliation: Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, People's Republic of China. healthwealthyhappy@yahoo.com.cn
authors.forename: Lijun
authors.initials: L
authors.lastname: Yuan
authors.forename: Tiesheng
authors.initials: T
authors.lastname: Cao
authors.forename: Yunyou
authors.initials: Y
authors.lastname: Duan
authors.forename: Guodong
authors.initials: G
authors.lastname: Yang
authors.forename: Zuojun
authors.initials: Z
authors.lastname: Wang
authors.forename: Litao
authors.initials: L
authors.lastname: Ruan
mesh_terms: D000328:Adult; D001021:Aortic Valve / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008943:Mitral Valve / Q000502:physiology*; D011664:Pulmonary Valve / Q000502:physiology*; D012016:Reference Values; D012119:Respiration; D014261:Tricuspid Valve / Q000502:physiology*