Microvascular flow, clinical illness severity and cardiovascular function in the preterm infant

Abstract

Objectives: Characterisation of the relationships between peripheral microvascular blood flow and measures of physiological and cardiovascular function in preterm infants in the immediate newborn period.

Design: Prospective observational cohort study.

Setting: Tertiary neonatal intensive care unit, New South Wales, Australia

Patients: Ninety-six preterm neonates (24-36 weeks gestation) admitted to NICU. Main Outcome Measure: Relationship between laser Doppler derived basal microvascular blood flow, functional echocardiographic measurements of cardiovascular status, mean arterial blood pressure and clinical illness severity at 24, 72, and 120 hours of age.

Results: At 24 hours of age multiple linear regression demonstrated a significant positive relationship, independent of gestational age, between baseline microvascular blood flow and CRIBII score (r2 = 0.442). Microvascular blood flow was inversely related to mean arterial blood pressure (r2= -0.563), and positively correlated with left ventricular output (r2= 0.435). Microvascular blood flow continued to exhibit a significant inverse relationship with mean arterial blood pressure (r2=-0.4) at 72 hours of age but by 120 hours no significant relationships were evident.

Conclusions: This is the first study to demonstrate that baseline microvascular blood flow in premature infants exhibits significant relationships with clinical illness severity and cardiovascular function in the immediate postnatal period. The effects of temporal and functional changes in the microvasculature on cardiovascular adaptation warrant further detailed study.