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Mesenteric blood flow velocity and its relation to transitional circulatory adaptation in appropriate for gestational
M Martinussen1, A M Brubakk, T Vik
1Department of Pediatrics, University Hospital, Trondheim, Norway.
Insights
Early postnatal mesenteric and systemic circulation in preterm infants differs from term infants. Preterm infants show unique hemodynamic responses to feeding, requiring compensatory changes to maintain stability.
Area of Science:
- Neonatal Physiology
- Cardiovascular Research
- Pediatric Gastroenterology
Background:
- Understanding early circulatory development in preterm infants is crucial for optimizing neonatal care.
- The mesenteric circulation's role in systemic hemodynamics during the early postnatal period is not fully elucidated in preterm neonates.
Purpose of the Study:
- To investigate the developmental changes in mesenteric and systemic circulation in preterm infants during the first week of life.
- To compare the hemodynamic responses to feeding in preterm infants with those previously reported in term infants.
Main Methods:
- Ultrasound Doppler measurements of blood flow velocity in the superior mesenteric artery, middle cerebral artery, and aortic orifice.
- Continuous monitoring of blood pressure and heart rate in 15 preterm infants.
- Serial assessments were conducted on postnatal days 1, 3, 4, 5, and 7, both pre- and postprandially.
Main Results:
- Between postnatal days 1 and 3, preterm infants showed decreased stroke volume but increased blood pressure and flow velocities in both the superior mesenteric and middle cerebral arteries.
- From day 3 to 7, preterm infants exhibited higher preprandial superior mesenteric artery end-diastolic flow velocity compared to term infants.
- Postprandially, preterm infants demonstrated a decrease in blood pressure and an increase in cardiac output, unlike term infants.
Conclusions:
- Healthy preterm infants exhibit distinct early postnatal circulatory adaptations compared to term infants.
- Feeding elicits unique systemic hemodynamic adjustments in preterm neonates, including blood pressure reduction and cardiac output augmentation.
- These findings highlight the need for tailored clinical management of feeding in preterm infants to accommodate their specific circulatory physiology.
Abstract:
We investigated the early postnatal changes of the mesenteric circulation and its relation to the systemic circulation in 15 preterm infants. The infants were studied before the first feeding on d 1 and pre- and postprandially on d 3, 4, 5, and 7. Blood flow velocity was measured by ultrasound Doppler in the superior mesenteric artery, middle cerebral artery, and the aortic orifice for cardiac output calculations. Blood pressure and heart rate were monitored. From d 1 to d 3, the preprandial stroke volume decreased [1.5 +/- 0.3 to 1.3 +/- 0.2 mL/kg (mean +/- SD), p < 0.05], whereas blood pressure (36 +/- 3 to 50 +/- 7 mm Hg, p < 0.001), superior mesenteric artery mean velocity (Vmean) (0.17 +/- 0.08 to 0.30 +/- 0.11 m/s, p < 0.05), and middle cerebral artery Vmean increased (0.15 +/- 0.05 to 0.22 +/- 0.03 m/s, p < 0.001). From d 3 through d 7, the preterm infants demonstrated higher preprandial end diastolic flow velocity in the superior mesenteric artery than we previously reported in term infants (0.15 +/- 0.05 versus 0.12 +/- 0.04, p < 0.05). Like the term infants, preterm infants increased their superior mesenteric artery Vmean by 83% postprandially and maintained a stable cerebral circulation with feeding. Unlike the term infants, feeding in the preterm infants induced a blood pressure decrease (51 +/- 6 to 48 +/- 6 mm Hg, p < 0.01) and a cardiac output increase (176 +/- 30 to 188 +/- 32 mL/kg/min, p < 0.001). These findings suggest that, in contrast to term infants, healthy preterm infants require compensatory systemic hemodynamic changes in response to feeding.