title: Increased pulmonary artery systolic storage associated with improved ventilation-to-perfusion ratios in acute respiratory distress syndrome.
abstract: OBJECTIVE
  The possibility that the increased pulmonary artery systolic storage (PASS) correlates with an improved distribution of ventilation/perfusion (V(A)/Q) and hence benefits gas exchange in acute respiratory distress syndrome (ARDS) was examined. Pulmonary artery systolic storage is the fraction of stroke volume stored in PA during systole and then discharged to the capillaries. The increased PASS can augment the diastolic pulmonary capillary blood flow (PCBF), which can then increase capillary blood volume participating in gas diffusion. We examined this by assessing the correlation between PASS and physiologic dead space to tidal volume (VD/VT) ratio.
  
  
  METHODS
  Included were 17 patients with ARDS. By using nitrous oxide-airway-pneumotachographic method, we measured the instantaneous PCBF, from which PASS was determined. Because PASS is the same as the flow volume of PCBF during diastole, PASS was determined from the flow volume of PCBF during diastole divided by the flow volume of PCBF during a whole cardiac cycle. The VD/VT ratio, used as an index of V(A)/Q, was measured by using the Bohr equation.
  
  
  RESULTS
  There was a good inverse correlation between PASS and VD/VT (r(2) = 0.785, P < .0001).
  
  
  CONCLUSIONS
  Our data indicate that the increased PASS correlates with an improved distribution of V(A)/Q and hence benefits gas exchange in ARDS.
authors.affiliation: Department of Anesthesiology and Pain Medicine, School of Medicine, Pusan National University, Yangsan, Gyeongnam, 626-770 Republic of Korea. charles6133@msn.com
authors.forename: Charles
authors.initials: C
authors.lastname: Her
authors.forename: Seung-Hoon
authors.initials: SH
authors.lastname: Baek
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Shin
authors.forename: Hyeon-Jeong
authors.initials: HJ
authors.lastname: Lee
mesh_terms: D000328:Adult; D000368:Aged; D001810:Blood Volume / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011651:Pulmonary Artery / Q000502:physiology*; D011652:Pulmonary Circulation / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012126:Respiratory Dead Space / Q000502:physiology; D012128:Respiratory Distress Syndrome / Q000503:physiopathology*; D013599:Systole / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology; D014692:Ventilation-Perfusion Ratio / Q000502:physiology*; D055815:Young Adult