Volume Expansion Does Not Alter Cerebral Tissue Oxygen Extraction in Preterm Infants with Clinical Signs of Poor Perfusion

Abstract

Background: Preterm infants with signs of poor perfusion are often treated with volume expansion, although evidence regarding its effect on cerebral perfusion is lacking. Moreover, the effect is questionable in preterm infants with an adequate cerebrovascular autoregulation (CAR). A useful measure to assess perfusion is cerebral fractional tissue oxygen extraction (cFTOE). Objectives: To assess the effect of volume expansion on cFTOE in preterm infants with signs of poor perfusion. Methods: In this observational study, we assessed cFTOE using near-infrared spectroscopy in preterm infants with signs of poor perfusion before, during and 1 h after volume expansion treatment. Simultaneously, we measured mean arterial blood pressure (MABP). We tested the effect of volume expansion on both cFTOE and MABP, using multi-level analyses. We intended to define a subgroup that responded to volume expansion with an increase in blood pressure and a decrease in cFTOE, suggesting absent CAR. Results: In 14 preterm infants, with a median gestational age of 26.7 weeks (25.0-28.7 weeks) and a median birth weight of 836 g (615-1,290 g), we found a small increase in MABP during (1.4 ± 1.4 mm Hg, p = 0.003) and after (1.8 ± 1.7 mm Hg, p = 0.001) volume expansion, but no change in cFTOE during (-0.19 ± 0.1% p = 0.44) or after (-0.53 ± 0.1% p = 0.34) volume expansion. We were unable to define a subgroup lacking CAR. Conclusions: Cerebral perfusion, as assessed by cFTOE, does not improve in preterm infants with signs of poor perfusion following volume expansion. In these infants, either CAR is present or volume expansion is inadequate to affect cFTOE.

Early blood pressure, antihypotensive therapy and outcomes at 18–22 months’ corrected age in extremely preterm infants

“…It is possible that the parameters other than a numerical threshold for low BP may better identify infants at risk for a poor outcome who would benefit from therapy. Incorporation of indirect measures of systemic or cerebral blood flow may also partially explain the observed variability in BP management, including why some infants without low BP received an antihypotensive therapy while other infants with low BP did not 3 14 22 23…”

“…Alternatively, factors beyond the immediate postnatal period may have more influence on toddler age outcomes thus masking the impact of early BP management on neurodevelopment 25. Lastly, given the complexity of the immature cardiovascular system, antihypotensive therapies may inconsistently influence cardiac function such that they do not uniformly alter early postnatal cerebrovascular blood flow or oxygen delivery 18 22 23…”

Brain-Sparing in Intrauterine Growth Restriction: Considerations for the Neonatologist

“…Also, the absolute blood pressure values may not correlate with cerebral perfusion [88,89]. Interestingly, cerebral oxygenation has been shown to predict neurodevelopmental outcome better than the presence of hypotension defined by absolute blood pressure values [90].…”

Blood Pressure during the Immediate Neonatal Transition: Is the Mean Arterial Blood Pressure Relevant for the Cerebral Regional Oxygenation?

“…Near-infrared spectroscopy allows the measurement of cerebral regional oxygen saturation (crSO 2 ) and calculation of cerebral fractional tissue oxygen extraction (cFTOE) [14] by taking SpO 2 into account. Fractional oxygen extraction represents the relation between oxygen delivery and oxygen consumption; cFTOE can be used as a proxy for cerebral fractional oxygen extraction and decreases until minute 5 after birth [12,15,16], and CBF depends on vascular resistance and blood pressure. An observational study in extremely low birth weight infants has demonstrated a pressure dependent cerebral oxygenation, indicating an impaired control of cerebral vascular resistance and dysfunction of cerebral autoregulation during the first week of life [17].…”