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Rune B Strandby,1 Rikard Ambrus,1 Michael P Achiam,1 Amalie Henriksen,1 Jens P Goetze,2 Niels H Secher,3 Lars B Svendsen11Department of Surgical Gastroenterology; 2Department of Clinical Biochemistry; 3Department of Anesthesiology, Rigshospitalet, University of Copenhagen, Copenhagen, DenmarkPurpose: Changes in plasma pro-atrial natriuretic peptide (proANP) may indicate deviations in the central blood volume (CBV). We evaluated the plasma proANP response to hypotensive hypovolemia under the influence of thoracic epidural anesthesia (TEA) in pigs. We hypothesized that plasma proANP would decrease in response to hypotensive hypovolemia and that TEA would aggravate the proANP response, reflecting a further decrease in CBV. Design: Randomized, blinded, controlled trial. Setting: A university-affiliated experimental facility. Participants: Twenty pigs randomized to administration of saline (placebo) or bupivacaine with morphine (TEA) in the epidural space at Th8-Th10. Interventions: Relative hypovolemia was established by an inflatable Foley catheter positioned in the inferior caval vein just below the heart (caval obstruction), and hemorrhage-induced hypovolemia was by withdrawal of blood from the femoral artery, both aiming at a mean arterial pressure (MAP) of 50–60 mmHg. Hemodynamic variables and plasma proANP were determined before and after the interventions. Results: Caval obstruction and withdrawal of blood reduced MAP to 50–60 mmHg. Accordingly, cardiac output, central venous pressure, and mixed venous oxygen saturation decreased (p |
