Effect of Dobutamine on Lung Microvascular Fluid Flux in Sheep with “Sepsis Syndrome”: Specific Measurements
We collected pulmonary lymph in graduated heparinized tubes. From pooled lymph specimens, we measured total protein and albumin concentrations (in grams per deciliter) by the Biuret method using an automated system (Auto Analyzer, Technicon Instruments); duplicate samples differed by less than 5 percent. At the time of lymph collection, we also measured total protein and albumin concentration (in grams per deciliter ). With appropriate temperature corrections, we measured oxygen tension (Po2, in millimeters of mercury) (AME-1 blood gas analyzer) and oxygen saturation (So2, in percent) (Hemoximeter, Radiometer) of both arterial (eg, Pa02) and mixed venous (eg, Pv02) blood drawn from the carotid arterial line and the distal lumen of the right-heart catheter, respectively. Blood for determining gas levels was drawn into heparinized syringes and maintained in ice until determination was performed within 15 minutes of collection.
We measured systolic, diastolic, and mean values for systemic blood pressure and for pulmonary arterial pressure and measured left atrial (LAP) and pulmonary arterial wedge pressures (PCWP) with an arterial/venous pressure transducer (Hewlett-Packard) and a digital display with a continuous paper recording system (Hewlett-Packard arterial/venous pressure module 78205B). Transducers were leveled to the humeral tuberosity, taken as the level of the right atrium in sheep. The cardiac output (in liters per minute) (CO) was determined in triplicate by a thermodilution technique with a portable computer (Edwards model 9520), using 10 ml of iced saline solution (0° C). canadian drug mall
We calculated the colloid osmotic pressure in both serum (Trmv) and lymph (Trpmv) and corrected for the albumin/globulin ratio. The pulmonary vascular resistance index (PVRI), stroke volume index (SVI), systemic oxygen consumption (Vo2) and oxygen transport, (02+) indexed for body surface area (BSA), were calculated from measured hemodynamic parameters. Body surface area for sheep was caculated by the following formula: BSA = (weight in kg X [0.75]/l,000). We calculated the mean hydrostatic pressure within the pulmonary microcirculation (Pmv) as follows: Pmv = LAP+ 0.4 (mean PAP —LAP), where LAP is left atrial pressure and PAP is mean pulmonary arterial pressure. From lymph flow (Qiym; in milliliters per 15 minutes) and [L/P]TP, we also calculated the clearance of lymph protein (CLP) as: Qlym X [L/P]TP (in milliliters per 15 minutes).
Data are expressed as the mean ± standard deviation. Statistical comparisons were made using Students paired or unpaired £-test, as indicated, and a p value of less than 0.05 was considered significant. Regression analyses were also used with independent variables to describe and predict a dependent variable as a function of these variables.