Hemodynamic effects of intravenous morphine infusion in ventilated preterm babies.

BACKGROUND

the importance of sedation and analgesia of newborn babies in intensive care is only now receiving recognition in many neonatal units.

OBJECTIVE

to evaluate the hemodynamic effects of morphine on Cerebral Blood Flow velocities (CBFv), Cardiac Output (CO), Stroke Volume (SV), Mean Arterial Blood Pressure (MABP) and Heart Rate (HR) in ventilated preterm infants, before and during the infusion of a loading dose.

DESIGN

prospective, open, non-randomized, before-after intervention study with hemodynamic measurements made by Doppler ultrasound.

SETTING

neonatal Intensive Care Unit, Tertiary Care Center.

PATIENTS: sequential sample of 30 ventilated preterm newborns (gestational age (GA) 29 +/- 2 wks, range 27-31, birth weight (BW) 1240 +/- 440 g, range 800-1680).

INTERVENTION: each subject received an intravenous loading dose of morphine (100 mcg/Kg/h) for 2 h, followed by a continuous infusion of 25 mcg/kg/h.

MEASUREMENTS: the following Doppler parameters of the anterior cerebral artery were estimated: Peak systolic flow velocity (Vs), end-diastolic flow velocity (Vd), mean flow velocity (Vm) and Pourcelot' Resistance Index (RI). Measurements of CBFv, CO and SV (by Doppler ultrasound), MABP and HR were made 30 min before (baseline values) and at 15 (M15), 30 (M30), 60 (M60) and 120 min (M120), during the morphine loading infusion. Statistical evaluation analysis of variance, significance was calculated by Student-Newman-Kenfeld test.

RESULTS

there were no statistically significant changes in the cerebral and cardiac Doppler parameters before or during the 120 min of morphine loading infusion. There was a non-significant fall in MABP (MABP: Baseline value = 44 +/- 6 mmHg, M120 = 42 +/- 4 mmHg; reduction = 4%) and HR (HR = Baseline value = 148 +/- 12 beats/min., M120 = 140 +/- 16 beats/min.; reduction = 5%).

CONCLUSIONS

a loading dose of morphine over 2 h did not have any significant effect on MABP or cerebral and cardiac hemodynamics. No adverse effects were noted that could be attributed to morphine therapy.