title: Angiotensin II formation and endothelin clearance in ARDS patients in supine and prone positions.
abstract: OBJECTIVE
  In patients with acute respiratory distress syndrome (ARDS), the prone position may enhance oxygenation by changing ventilation/perfusion ratio. In this study, we investigated whether the prone position affects the net balance between pulmonary endothelin (ET-1) and angiotensin II (Ang II) production and clearance, two metabolic functions of lung endothelial cells.
  
  
  METHODS
  Anaesthesiological intensive care unit of a university hospital.
  
  
  METHODS
  Ten ARDS patients (Murray score > 2.5) were studied in both the supine position (SP) and the prone position (PP). MEASUREMENTS AND DESIGN: Blood samples were taken simultaneously from the patient in SP for assessment of mixed venous and arterial ET-1 and Ang II concentrations, and plasma renin concentration (PRC). This was repeated after 60 min in SP, immediately after turning the patient into PP, and 60 min thereafter. Net arterial/mixed venous ET-1 clearances and net Ang II formations were calculated.
  
  
  RESULTS
  arterial oxygen tension increased from SP to PP by an average of 60 mmHg, about 20%. Arterial ET-1 concentrations of ARDS patients were 1.57 +/- 1.1 pg/ml (mean +/- SD) and within the range of healthy persons. Net ET-1 clearances were negative in SP, indicating pulmonary release of ET-1, and did not change in PP. Arterial Ang II concentrations (73 +/- 56 pg/ml) as well as PRC (126 +/- 85 pg/ml) were markedly elevated. Net transpulmonary Ang II formation did not change.
  
  
  CONCLUSIONS
  Acute changes of oxygenation in ARDS patients by positioning do not induce any short-term effects on pulmonary ET-1 net clearance or Ang II net formation.
authors.affiliation: Clinic of Anesthesiology and Operative Intensive Medicine, Universitätsklinikum Charité Campus Virchow-Klinikum, Berlin, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Wenz
authors.forename: B
authors.initials: B
authors.lastname: Hoffmann
authors.forename: J
authors.initials: J
authors.lastname: Bohlender
authors.forename: G
authors.initials: G
authors.lastname: Kaczmarczyk
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D000804:Angiotensin II / Q000097:blood*; D016638:Critical Illness; D019332:Endothelin-1 / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D016684:Prone Position; D012083:Renin / Q000097:blood; D012128:Respiratory Distress Syndrome / Q000097:blood / Q000378:metabolism*; D012720:Severity of Illness Index; D016683:Supine Position
chemical_list: D019332:Endothelin-1; D000804:Angiotensin II; D012083:Renin