Inhaled gases affect the ultrasound contrast produced by Albunex in anesthetized dogs

In anesthetized animals maintained with isoflurane using 100% oxygen as a carrier gas, Albunex (Molecular Biosystems, Inc., San Diego, Calif.) produced no ultrasound contrast in the left ventricle after intravenous administration. The current study tested the hypothesis that the inhalation of gas mixtures with increased concentrations of oxygen decreased the quality and duration of Albunex-induced contrast. Albunex (0.22 mL/kg) was injected intravenously into anesthetized dogs (n = 9) breathing compressed air, oxygen, mixtures of oxygen and nitrogen, or combinations of oxygen and nitrous oxide. Albunex produced ultrasound contrast of shorter duration and decreased quality during the inhalation of gas mixtures containing increased amounts of oxygen. In the presence of inhaled gas mixtures containing nitrous oxide, Albunex produced no contrast in the left ventricle, regardless of the oxygen content. These data indicate that the inhalation of gas mixtures containing smaller amounts of nitrogen, compared with air, decreased the ability of Albunex to cause ultrasound contrast in the heart after intravenous administration.