[Effect of dobutamine on intra-pulmonary shunt]

A study of the development of intra-pulmonary shunts was carried out in ten subjects following an intra-venous administration of a 7.5 microgram/kg/min dose of dobutamine by electric syringe. All the subjects were on a respirator (FiO2=0,6 most often) and frequently with P.E.E.P. The shunts were determined at the FiO2 by which the subject was being treated. The cardiac flow was measured by thermodilution. In 9 cases out of 10 the intra-pulmonary shunt is sharply increased already in the first half hour by dobutamine. The shunt values are in the order of: -- 17.94p. 100 +/- 7.19 before the drug -- 26.50 p. 100 +/- 12.85 half an hour after the infusion beginning. The shunt increase is thus 47p. 100 of the average original value after half an hour, which is significant (p less than 0.01). The shunt is then stable at the attained value (hourly average : 26.05 +/- 12.25). These observations are discussed in relation to the obtained effects on the cardiac outout, to the PaO2, and to the quantity of transported arterial oxygen. It appears in this series that, in spite of the shunt increase, there is no risk of cellular oxygen deficiency.