Cardiovascular effects of an intravenous bolus of morphine in the ventilated preterm infant

Aim To examine the cardiovascular effects of an intravenous bolus of morphi ne, 100 mu g/kg, in 17 ventilated preterm infants. Methods-Heart rate and blood pressure were monitored. Right ventricular out put, superior vena caval flow, and the width of the ductus arteriosus were measured by Doppler echocardiography 10 and 60 minutes after the morphine i njection, and the values compared with baseline values by the paired t test . Results-There was a small but significant fall in heart rate (2.1% at 10 mi nutes, 4.3% at 60 minutes) consistent with a sedative effect. There was no effect on systolic, diastolic, or mean blood pressure. There was no signifi cant effect on systemic blood flow as measured by either right ventricular output: or superior vena caval flow. Ductal width was significantly reduced by a mean of 16% at 60 minutes, suggesting that normal duct closure was no t inhibited. Conclusion-No cardiovascular effects of an intravenous bolus of morphine co uld detected.