51 Effect of Volume Expansion on Cerebral Blood Flow in Hypotensive Preterms

Abstract

Background and aims: To ensure adequate perfusion of the brain, cerebral autoregulation limits cerebral blood flow (CBF) to a certain range. Preterm infants might lack autoregulation, and when hypotensive, be at risk for cerebral damage. Frequently used treatment for hypotension is volume expansion. We aimed to determine the effect of volume expansion (crystalloid) in hypotensive preterms on fractional cerebral tissue oxygen extraction (FTOE), a measure for CBF. Methods: Preterm infants with a mean arterial blood pressure (MABP) below their GA, who received volume expansion (15 ml/kg) within the first week of life, were included. Near-infrared spectroscopy was used to measure regional cerebral oxygen saturation (rcSO2). Transcutaneous arterial oxygen saturation (tcSaO2) was measured simultaneously. FTOE was calculated: (tcSaO2-rcSO2)/tcSaO2. We analyzed 2 episodes of 1h immediately before, and 2 hours after treatment, using Mann-Whitney-U-test. Results: Twelve measurements in 10 preterms (7 female, median GA 27.9 weeks (range 25.6-31.3), BW 1064 grams (676-1780), 1.7 days old (0.5-6.9), CRIB-score 4 (1-9)) were analyzed. MABP increased in 10 cases (median 29.5 to 32.0 mmHg), though not significantly (p=.21). FTOE did not change accordingly (median 0.26 to 0.24, p=1.0). Conclusions: Volume expansion tends to increase MABP but has no effect on FTOE. However, FTOE before volume expansion was always within the normal range. The question arises whether volume expansion is warranted in preterm infants in case of marginally low blood pressure. Due to the lack of effect on MABP and limited numbers investigated, no conclusion regarding cerebral autoregulation can be drawn.