[An experimental study on the appropriate proportion of dopamine and dobutamine for mixed infusion to treat...

This study was aimed to investigate appropriate proportion for combined use of dopamine (DA) and dobutamine (DB) to treat cardiopulmonary dysfunction. The total dose of 10 micrograms.kg-1.min-1 with several different proportions in steps of 2 micrograms.kg-1.min-1 of DA and DB was administered to mongrel dogs with intact lung and with cardiopulmonary dysfunction caused by lung edema induced by oleic acid instillation. The hemodynamic variables during and after the infusion with the combined dosages of both agents were compared with that of baseline values. In dogs with intact lung, cardiac index (CI) increased significantly in all proportions of both agents. The levels of CI tend to increase prominently when the proportion of DB in the mixture was increased. Heart rates showed a tendency to increase with higher proportion of DB. Increasing proportions of DA caused a more increase of arterial pressure than by increasing that of DB. In dogs with pulmonary edema, these hemodynamic characteristics with the proportional changes of both drugs were demonstrated more significantly than in normal dogs. From these results, it was concluded that the appropriate combined preparation of both agents to increase CI without extreme tachycardia in dogs with cardiopulmonary dysfunction was the mixed solution of DA 2-4 micrograms.kg-1.min-1 and DB 6-8 micrograms.kg-1.min-1.