Angiotensin II formation and endothelin clearance in ARDS patients in supine and prone positions.
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.
Wenz
M
M
Clinic of Anesthesiology and Operative Intensive Medicine, Universitätsklinikum Charité Campus Virchow-Klinikum, Berlin, Germany.
Hoffmann
B
B
Bohlender
J
J
Kaczmarczyk
G
G
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
D019332:Endothelin-1; D000804:Angiotensin II; D012083:Renin