Time course of the effects of epoprostenol on effective pulmonary blood flow in normal volunteers.

Abstract

1 Epoprostenol (prostacyclin) has been widely used as a vasodilator, but its effects on cardiac output are controversial and the time course of its effects little studied.2 We report its cardiovascular effects in doses of 5 and 10 ng kg-' min-' in six healthy volunteers. 3 Each of the two doses caused a mean 20% rise in effective pulmonary blood flow and a 15% rise in heart rate. These effects appeared to reach a maximum within 10 min of starting or increasing the rate of infusion, with no evidence of a rebound effect. 4 When the dose was reduced, heart rate and effective pulmonary blood flow appeared to reach a new steady state within 5 min of reducing or stopping the infusion. Only minor side-effects were encountered, and they were rapidly reversed on stopping the drug. 5 These results should be applied to the therapeutic use of epoprostenol as a vasodilator, particularly when titrating the optimum dose for a given individual.

Effect of infused adenosine on cardiac output and systemic resistance in normal subjects.

“…The heart rate was recorded every 15 s on a single channel ECG machine, and measured from the R-R interval. Since we had previously shown that the measurement of Qp.eff significantly affects heart rate (Bush et al, 1988), we took the mean of the six measurements from 15 to 90 s in the cycle illustrated in Figure 1. All other heart rate data were discarded.…”

“…It was measured from the time constant of the fall in the partial pressure of freon-22. A fixed time interval was used for the calculation (12-24 s from the start of the manoeuvre for all subjects), because a previous study had shown that this yielded more reproducible results than selecting a linear portion by eye (Bush et al, 1988), using this method. The mean coefficient of variation of Qp.eff within a study is 5.5% (Bush et al, 1988), and between studies is 6.5% (Waller, 1982).…”

“…A fixed time interval was used for the calculation (12-24 s from the start of the manoeuvre for all subjects), because a previous study had shown that this yielded more reproducible results than selecting a linear portion by eye (Bush et al, 1988), using this method. The mean coefficient of variation of Qp.eff within a study is 5.5% (Bush et al, 1988), and between studies is 6.5% (Waller, 1982). Systolic, diastolic and mean blood pressure (respectively SBP, DBP, MBP; mm Hg) were measured ultrasonically using a Dinamapp vital signs monitor (Critikon Ltd, USA), which is in good agreement with aortic pressure measured invasively (Borow & Newburger, 1982).…”

Comparison of the cardiovascular and pulmonary effects of oral celiprolol, propranolol and placebo in normal volunteers.

“…The mean within study coefficient of variation (100 x s.d./mean) of EPBF has been shown to be 5.5% (Bush et al, 1988). The between study mean coefficient of variation of EPBF has been shown to be 6.5% (Waller, 1982).…”

“…EPBF was measured from the time constant of the fall in the partial pressure of freon-22 between a previously fixed time interval (usually 10-20 s from the start of the manoeuvre), because a previous study had shown that this yielded more reproducible results than selecting a linear portion by eye (Bush et al, 1988). The mean within study coefficient of variation (100 x s.d./mean) of EPBF has been shown to be 5.5% (Bush et al, 1988).…”