Abstract 398 Poster Session III, Monday, 5/3 (poster 156)

Wide fluctuations in cerebral blood flow velocities (CBFV) leading to intraventricular hemorrhage (IVH) have been reported in infants on assisted ventilation. Muscular paralysis or sedation to decrease functions in CBFV are recommended. However, CBFV does not reflect true blood flow. Power Doppler technique (PD) allows to detect low flow signals without the need frequency filter, free from aliasing, and angle independent. Thus PD expresses tissue perfusion. Using PD technique we studied cerebral blood perfusion(CBP) in twenty infants: 1). Receiving morphine infusion.(M, n=10) 2). Control (C, n=10) no morphine. Their gestational age ranged from 26-35 wks and B. wt.ranged from 810-2750 g. All were on assisted ventilation, randomized either to M or C group. Morphine was given first as a bolus 100 µg/kg over 30 min., then maintained at 20 µg/kg/hr continued for 1 to 5 days. Infants head was scanned for IVH. Grayscale and PD recording were made from anterior fontanel (3 regions) coronal plane, basal ganglia and brainstem, mid sagittal plane pellucidi. Recording were performed before morphine infusion, 3 times on day (1st & 3rd) of infusion, & 3 one day after infusion(4th, 5th & 6th). The images from PD were recorded on magnetic tapes and analyzed. Mean PD signals were calculated. Polynomeal regression analysis was used to calculate the mean & 80 % confidence intervals of PD signals in relation to time of examination. The data from the control & morphine were compared. In C PD signals in midcoronal plane, basal ganglia and sagittal plane all increased significantly from baseline during first & second examinations then decreased significantly during 5th-6th examinations. These changes corresponded to high PIPP & higher BP on 1st examination. In M group also the signals increased though were lower than the controls during 1st day of sedation & decreased after infusion was stopped. The PIPP score was significantly lower in M group. The control groups had higher PD values than morphine group in all subregions but did not reach statistical significance. These data show that CBP significantly increased during 1st day in both control & morphine group. The PD values were higher in control but not statistically different. they also show a trend in slow & significant increase in PD values during the 3rd-4th examinations in each group. It may be concluded that morphine sedation decreases CBP relative to control group. This corresponding to lower PIPP score in M group. On the other hand PIPP score in the control group was significantly higher during day one. These data substantiate the effect of sedation on stabilizing blood flow as seen in this study. It should be noted there was an increase in mean arterial pressure during these periods.