title: Reductions in central venous pressure by lower body negative pressure or blood loss elicit similar hemodynamic responses.
abstract: The purpose of this study was to compare hemodynamic and blood analyte responses to reduced central venous pressure (CVP) and pulse pressure (PP) elicited during graded lower body negative pressure (LBNP) to those observed during graded blood loss (BL) in conscious humans. We hypothesized that the stimulus-response relationships of CVP and PP to hemodynamic responses during LBNP would mimic those observed during BL. We assessed CVP, PP, heart rate, mean arterial pressure (MAP), and other hemodynamic markers in 12 men during LBNP and BL. Blood samples were obtained for analysis of catecholamines, hematocrit, hemoglobin, arginine vasopressin, and blood gases. LBNP consisted of 5-min stages at 0, 15, 30, and 45 mmHg of suction. BL consisted of 5 min at baseline and following three stages of 333 ml of hemorrhage (1,000 ml total). Individual r(2) values and linear regression slopes were calculated to determine whether the stimulus (CVP and PP)-hemodynamic response trajectories were similar between protocols. The CVP-MAP trajectory was the only CVP-response slope that was statistically different during LBNP compared with BL (0.93 ± 0.27 vs. 0.13 ± 0.26; P = 0.037). The PP-heart rate trajectory was the only PP-response slope that was statistically different during LBNP compared with BL (-1.85 ± 0.45 vs. -0.46 ± 0.27; P = 0.024). Norepinephrine, hematocrit, and hemoglobin were all lower at termination in the BL protocol compared with LBNP (P < 0.05). Consistent with our hypothesis, LBNP mimics the hemodynamic stimulus-response trajectories observed during BL across a significant range of CVP in humans.
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota;
authors.forename: Blair D
authors.initials: BD
authors.lastname: Johnson
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; Department of Physiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands;
authors.forename: Noud
authors.initials: N
authors.lastname: van Helmond
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota;
authors.forename: Timothy B
authors.initials: TB
authors.lastname: Curry
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota; and.
authors.forename: Camille M
authors.initials: CM
authors.lastname: van Buskirk
authors.affiliation: U.S. Army Institute of Surgical Research, Fort Sam Houston, Texas.
authors.forename: Victor A
authors.initials: VA
authors.lastname: Convertino
authors.affiliation: Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota; Joyner.Michael@mayo.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Joyner
mesh_terms: D000328:Adult; D001127:Arginine Vasopressin / Q000378:metabolism; D062186:Arterial Pressure / Q000502:physiology; D001784:Blood Gas Analysis / Q000379:methods; D002395:Catecholamines / Q000378:metabolism; D002496:Central Venous Pressure / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006400:Hematocrit / Q000379:methods; D006439:Hemodynamics / Q000502:physiology*; D006454:Hemoglobins / Q000378:metabolism; D006470:Hemorrhage / Q000378:metabolism / Q000503:physiopathology*; D006801:Humans; D008150:Lower Body Negative Pressure / Q000379:methods; D008297:Male; D009638:Norepinephrine / Q000378:metabolism
chemical_list: D002395:Catecholamines; D006454:Hemoglobins; D001127:Arginine Vasopressin; D009638:Norepinephrine
keywords: blood pressure; central hypovolemia; heart rate; hemorrhage; stroke volume