Acute and long-term effects of fluosol-DA 20% on respiratory system mechanics and diffusion capacity in dogs

We evaluated the acute and cumulative effects of Fluosol-DA 20% (Fluosol, Alpha Therapeutics, Los Angeles) on respiratory system mechanics and the diffusing capacity for carbon monoxide (D_LCO) in six dogs. A total dose of 45 to 75 mL/kg was administered during a period of eight to 12 days. After a loading dose of 15 mL/kg was a dose of 10 mL/kg was administered intravenously on alternate study days in four dogs and on successive days in two dogs. There were no significant differences between the initial and final study day in total lung capacity (TLC), residual volume (RV), static lung compliance (C_STAT), dynamic lung compliance (C_DYN), the retractive force at 50% at TLC (P_{50 TLC}), and the diffusion capacity for carbon monoxide (C_LCO). Although there was a small increase in the total pulmonary resistance (R_TP, 0.8 to 1.8 cm H₂O/L/s; P < .05), its absolute value remained in the normal range. In contrast to the lack of chronic dose-dependent and time-dependent changes in lung mechanics and D_LCO, there was a transient decrease in CDYN, from 0.066 to 0.047 L/cm H₂O, and an increase in R_TP, from 1.44 to 4.83 cm H₂O/L/s (P < .001), immediately following the infusion of Fluosol. We conclude that an increase in pulmonary resistance to airflow is part of the idiosyncratic acute reaction after the administration of Fluosol, while the repeated administration of Fluosol has little effect on pulmonary gas transfer assessed by C_LCO and respiratory system mechanics.