[Effects of propofol infusion on respiration, systemic circulation and regional organ blood flow]

Using a nonradioactive colored microsphere (CMS) method, we measured the regional organ blood flow in rats before, during and after constant flow infusion of propofol (PF). Eighty-seven male Sprague-Dawley rats weighing 408 +/- 12 g (mean +/- SD) were used for the experiment. Spontaneous respiration was maintained throughout the course of the experiment. The infusion of PF was started from the right femoral vein at a constant rate of 5 mg.kg-1.h-1 for the first 30 minutes. CMSs of three different colors were injected through the catheter placed between the left ventricle and the right common carotid artery before, during, and 15 min after PF infusion, respectively. At the end of the experiment, the animals were sacrificed, and the quantity of CMSs trapped in the heart, liver, gastrointestinal (G-I) tract, spleen, and kidneys was measured by the matrix inversion technique. Neither pulse rate nor arterial blood pressure declined significantly during or after the PF infusion. No significant change was observed in arterial blood gas analysis (pH, PaCO2, PaO2, HCO3-, and base excess), as a monitor of respiration of the animals, during or after PF anesthesia. Nor did cardiac output change significantly. Regional organ blood flow, i.e., blood flow in the right and left ventricles, hepatic arterial blood flow, portal venous blood flow, and renal blood flow all remained constant during and after the PF anesthesia. In conclusion, during PF anesthesia at the rate of 5 mg.kg-1.h-1 both systemic circulation and regional organ blood flows were maintained within normal range without any respiratory depression, indicating that PF can be useful for intravenous sedation of outpatients.