Vasoactive drugs may increase intrapulmonary shunt in patients with permeability edema. Because 7.5% hypertonic saline solution has cardiotonic properties, we studied its hemodynamic and pulmonary effects in a canine model of oleic acid-induced lung injury. Immediately after saline infusion, there were increases in cardiac output (2.0 ± 0.1 to 3.4 ± 0.2 L/min; p < .001) and intrapulmonary shunt (50.3 ± 4.4 to 57.3 ± 3.2%; p < .01) without alteration in arterial or mixed venous oxygen tension. Although arterial oxygen content decreased from 16.4 ± 1.1 to 14.4 ± 0.9 ml/dl (p < .001, paralleling the change in hemoglobin concentration, oxygen delivery to the tissues increased from 327 ± 23 to 486 ± 36 ml/min (p < .001). These effects were transient, inasmuch as all values returned to preinfusion levels within 30 min. Tissue oxygen consumption increased proportionately with cardiac output, and the directional change in arterial oxygenation was similar to the change in mixed venous oxygen tension. We conclude that tissue oxygen delivery improves after hypertonic saline infusion despite changes in intrapulmonary shunt and oxygen consumption. However, any benefit appears to be transient.
ASJC Scopus subject areas
- Critical Care and Intensive Care Medicine