PULMONARY EXTRACTION OF DOBUTAMINE IN CRITICALLY ILL SURGICAL PATIENTS

This study was conducted to assess the pulmonary extraction of dobutam ine. Eleven patients admitted to the general surgical intensive care u nit, with varying diagnoses requiring dobutamine as part of their ther apeutic intervention, were included. A single simultaneous sample was drawn, at the clinically required rate of infusion, from the radial an d pulmonary artery catheter sites. Total dobutamine clearance was dete rmined using the pulmonary artery (pre-lung) sample. The mean +/- SD t otal dobutamine clearance was 82 +/- 67 mL . kg(-1). min(-1) a value w hich is larger than the average cardiac output of plasma of 56 +/- 20 mL . kg(-1). min(-1). The mean percent pulmonary extraction fraction o f dobutamine was 3.6% +/- 22.5% (range -34-52), a value within the 9% coefficient of variability (CV) of the assay. However, five patients h ad pulmonary extraction greater than the CV of the assay. Of these fiv e patients, three had ''negative'' extraction values, and two had ''po sitive'' extraction values. There was no relationship between the perc ent pulmonary extraction of dobutamine and the rate or duration of dob utamine infusion before sampling. The results show that the extraction of dobutamine by the lungs is minimal.