AIM: To examine the hypothesis that intraventricular hemorrhage(IVH) results from a systemic hypoperfusion reperfusion cycle.

METHODS: 126 babies born before 30 weeks (mean gest 27 weeks, mean BW 991g) were studied with Doppler echocardiography and cerebral ultrasound at 5, 12, 24 and 48 hours of age. Superior vena cava (SVC) flow was assessed by Doppler echocardiography as a measure of systemic blood flow returning from the upper body and brain. This is necessary because atrial and ductal shunts can cause either ventricular output to significantly overestimate systemic blood flow. Other measures included colour Doppler diameters of ductal and atrial shunts, Doppler assessment of shunt direction and velocity and right and left ventricular outputs.

RESULTS: In 25 uncomplicated infants with normal lungs (mean gest 28.4 weeks), mean SVC flow rose from 68 mls/kg/min at 5 hrs to 88 mls/kg/min at 48 hrs. The lower limit of normal SVC flow was defined as 40 mls/kg/min(10th centile at 5 hrs).

Early IVH was present at 5 hours of age in 9 babies. Normal SVC flows were seen in these babies except in 3 whose IVH later extended, who all had SVC flow <30mls/kg/min at 5 and/or 12 hrs. These 9 babies had a significantly higher rate of vaginal delivery than the rest of the cohort (89% vs 34%, p=0.002).

Late IVH developed in 18 babies (grade 1-2, n=7; grade 3-4, n=11), 94% of whom had SVC flow below the normal range prior to development of an IVH, in 83% it was well below the normal range (<30mls/kg/min). Low SVC flow was not seen in 1 of these 18 babies. IVH was first seen after SVC flows had improved and the grade of IVH related significantly to the severity and duration of low SVC flow (p<0.001). Six of the babies (54%) who developed grade 3-4 IVH had a serious acute respiratory deterioration (5 pulmonary hemorrhages and 1 pneumothorax) in the same time period as the IVH occurred.

Other babies had low SVC flow and did not develop IVH. Of 27 babies with any measure of SVC flow <30 mls/kg/min, 63% developed IVH or PVL but 37%(n=10) had no ultrasound change. This latter group were significantly more mature (median gestation 28 vs 25 weeks, p=0.015).

CONCLUSIONS: Late IVH is a symptom of postnatal systemic hypoperfusion and occurs during subsequent reperfusion. The injury sustained relates to maturity, severity of hypoperfusion and clinical events which occur during the period that perfusion is improving. We speculate that early IVH is a symptom of peripartum hypoperfusion.