Effect of dobutamine on lung microvascular fluid flux in sheep with "sepsis syndrome"

The effect on pulmonary fluid balance of adrenergic receptor agonist agents commonly employed in clinical sepsis has not been well characterized. Therefore, we tested the hypothesis that dobutamine would increase pulmonary microvasular fluid flux in experimental sepsis-induced lung injury. To define the effects of this synthetic catecholamine on pulmonary lymph flow (QL), we infused dobutamine in sheep at two doses in sequence (5 micrograms/kg/min and 10 micrograms/kg/min) before and after the induction of intraperitoneal sepsis which resulted in the development of lung microvascular injury. In the nonseptic state, cardiac output increased at both 5 micrograms/kg/min and 10 micrograms/kg/min (22 and 36 percent, respectively), while QL was unchanged from baseline (for 5 micrograms, delta QL = +0.44 +/- 1.35 ml/15 min; not significant) (for 10 micrograms, delta QL = -0.20 +/- 1.0 ml/15 min; not significant). Values for the ratio of lymph/plasma total protein levels [( L/P]TP) fell modestly in the nonseptic study at both doses (p less than 0.05). With established sepsis syndrome, QL increased from the nonseptic baseline study (2.99 +/- 1.8 to 7.01 +/- 3.95 ml/15 min; p less than 0.05), without change in [L/P]TP ratios or the calculated microvascular hydrostatic pressure. (Pmv) During sepsis, dobutamine infusion was again associated with an increase in cardiac output at both the 5 micrograms/kg/min (+29 percent) and 10 micrograms/kg/min (+33 percent) doses, while QL increased modestly only with the lower dose of dobutamine infused (5 micrograms/kg/min, delta QL = 1.80 +/- 2.2 ml/15 min; p less than 0.05). In this model of sepsis-induced lung injury, dobutamine increased systemic flow without substantially augmenting QL.