title: Right atrial pressure affects the interaction between lung mechanics and right ventricular function in spontaneously breathing COPD patients.
abstract: BACKGROUND
  It is generally known that positive pressure ventilation is associated with impaired venous return and decreased right ventricular output, in particular in patients with a low right atrial pressure and relative hypovolaemia. Altered lung mechanics have been suggested to impair right ventricular output in COPD, but this relation has never been firmly established in spontaneously breathing patients at rest or during exercise, nor has it been determined whether these cardiopulmonary interactions are influenced by right atrial pressure.
  
  
  METHODS
  Twenty-one patients with COPD underwent simultaneous measurements of intrathoracic, right atrial and pulmonary artery pressures during spontaneous breathing at rest and during exercise. Intrathoracic pressure and right atrial pressure were used to calculate right atrial filling pressure. Dynamic changes in pulmonary artery pulse pressure during expiration were examined to evaluate changes in right ventricular output.
  
  
  RESULTS
  Pulmonary artery pulse pressure decreased up to 40% during expiration reflecting a decrease in stroke volume. The decline in pulse pressure was most prominent in patients with a low right atrial filling pressure. During exercise, a similar decline in pulmonary artery pressure was observed. This could be explained by similar increases in intrathoracic pressure and right atrial pressure during exercise, resulting in an unchanged right atrial filling pressure.
  
  
  CONCLUSIONS
  We show that in spontaneously breathing COPD patients the pulmonary artery pulse pressure decreases during expiration and that the magnitude of the decline in pulmonary artery pulse pressure is not just a function of intrathoracic pressure, but also depends on right atrial pressure.
authors.affiliation: Department of Pulmonary Diseases, VU University Medical Center, Amsterdam, The Netherlands. b.boerrigter@vumc.nl
authors.forename: Bart
authors.initials: B
authors.lastname: Boerrigter
authors.forename: Pia
authors.initials: P
authors.lastname: Trip
authors.forename: Harm Jan
authors.initials: HJ
authors.lastname: Bogaard
authors.forename: Herman
authors.initials: H
authors.lastname: Groepenhoff
authors.forename: Frank
authors.initials: F
authors.lastname: Oosterveer
authors.forename: Nico
authors.initials: N
authors.lastname: Westerhof
authors.forename: Anton
authors.initials: A
authors.lastname: Vonk Noordegraaf
mesh_terms: D000328:Adult; D001794:Blood Pressure; D005260:Female; D006325:Heart Atria; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000503:physiopathology; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D011669:Pulmonary Wedge Pressure / Q000502:physiology*; D012119:Respiration; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology*; D016278:Ventricular Function, Right / Q000502:physiology*