Presented at the Neonatal Society 2013 Summer Meeting.
Bates S, Odd D, Wach R, Evans D, Heep A
School of Clinical Science, University of Bristol, Neonatal Intensive Care Unit, Southmead Hospital, North Bristol NHS Trust, Bristol UK
Background: Assessment of superior vena cava flow (SVCF) on echocardiography is used to indirectly estimate cerebral perfusion in preterm infants. Impaired cerebral perfusion is thought to be a major contributor in the pathogenesis of intraventricular haemorrhage (IVH). Aim of the study was to look for an association between SVCF at <24h of age and clinical factors that contribute to the development of IVH in a cohort of patients at highest risk of developing IVH stratified by GA less 28 weeks.
Methods: Single centre retrospective cohort study. 247 infants (23+0-27+6weeks GA) admitted to Southmead Hospital tertiary NICU between 03/2008 and 01/2012 were enrolled. 109 patients had SVCF analysis and survived to 7 days. Retrospective clinical data collection, evaluation of medical history and independent re-assessment of digitalised stored cranial ultrasound (CrUS) examinations. Calculation of SVCF was as described by Kluckow et al. Statistical analysis using SPSS 17.0 (Student t-test; MWU test, multivariable logistic regression; ROC).
Results: The median GA of the study group was 25+4 weeks (23+2-27+5). 46/109 (42%) infants developed IVH defined on CrUS at day 7 postnatal age. SVCF measured at median 8.5h of life (range 1-23h). SVCF was significant lower (71ml/kg/min median, 30-140 ml/kg/min range) in infants diagnosed with IVH compared to infants with no IVH (84 ml/kg/min median, 27-200 ml/kg/min range, p=0.049). SVCF was inversely correlated to PDA size (r=-0.21: p=0.03). Infants with IVH were born with lower GA (24+5 versus 25+6 median; p=0.01), less antenatal steroids (p=0.02), higher incidence of spontaneous vaginal delivery (p=0.003), elevated INR at delivery (p=0.02) and lower platelet count at 24h of age (p=0.001). Multivariable logistic regression analysis (gender, GA, antenatal steroids, SVCF, CRP at 24h) did not confirm independent association of SVCF at <24h of age with development of IVH.
Conclusion: Our study results confirm low SVCF at <24h of life contributing to the pathophysiology of IVH in extremely preterm infants. Early postnatal echocardiographic assessment estimating PDA shunt and SVCF is prerequisite to balance cerebral perfusion in infants at risk of developing IVH.
Corresponding author: drsarahbates@hotmail.com
References
Kluckow M & Evans N. Superior vena cava flow in newborn infants: a novel marker of systemic blood flow (Arch Dis Child 2000; 82: F182-F187)