The Journal of surgical research
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Comparative Study
Transthoracic bioimpedance can measure extravascular lung water in acute lung injury.
We used a porcine endotoxemic model of acute lung injury to compare extravascular lung water (EVLW) measured by right transthoracic bioimpedance to postmortem gravimetric EVLW measurements. Adult pigs were randomized into control (N = 5) or endotoxin groups [150 microgram/kg Escherichia coli lipopolysaccharide B for 1 hr followed by 3 hr of resuscitation for a thermodilution cardiac output less than 90% of baseline using either isotonic saline (N = 5) or isooncotic albumin (N = 5)]. Right lung resistance was measured using a novel electrode array and a highly sensitive analyzer and was used to calculate right lung resistivity. ⋯ Using multiple regression analysis, a predictive equation for EVLW based on right lung resistivity, body weight, and mean pulmonary artery pressure was generated (r2 = 0.81; SEE = 0.60; P < 0.0001). These results demonstrate that right lung resistivity measurements can provide a noninvasive estimate of EVLW. In addition, crystalloid may be preferable to colloid for fluid resuscitation in noncardiogenic pulmonary edema.
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Pulmonary edema is a complication of critical care fluid management that may be restricted by the use of oncotically effective resuscitation fluids. Potentially beneficial oncotic properties of starch-based plasma volume expanders such as hetastarch (Het), pentafraction (Pen), and Dextran-70 (Dex) may be compromised by their broad range of molecular masses, some of which are small enough to filter from the circulation. Leakage of these molecules into the pulmonary interstitium may limit their oncotic effectiveness and enhance fluid filtration. We measured the filtration of these three resuscitation solutions into lung lymph to evaluate their oncotic contribution to pulmonary edema formation. ⋯ Pen and Het demonstrated greater oncotic effectiveness because of restricted plasma-to-lymph macromolecular filtration and limited transvascular fluid flux. By comparison, Dex filtered rapidly and increased transvascular fluid filtration. Pen appears to possess filtration properties that optimize critical care fluid management compared to currently available colloid solutions such as Het and Dex.
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beta-2-Adrenergic agents can increase mesenteric blood flow under normal conditions. However, the effects of dobutamine on regional blood flow in sepsis are less well defined since diverging results had been obtained in some studies due to the differences in animal models. In this fluid-resuscitated hyperdynamic endotoxic dog model, we studied the effects of dobutamine on mesenteric, renal, and femoral perfusion. ⋯ Femoral VO2 remained stable. No statistical differences were found between 5 and 10 microgram/kg x min dobutamine. In this hyperdynamic endotoxic shock model, administration of a limited dose of dobutamine could be useful to increase mesenteric blood flow and urine output.