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Andrew B. Kairalla MD, Editor
S.Venkataseshan M.D, D.M Guest Editor
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SVC flow in neonates
Background: Clinical methods of assessing
adequacy of the circulation are poor predictors of volume of blood
flow in the newborn preterm. Doppler echocardiography can be used to
assess perfusion at various sites in the circulation.
Objective: To assess repeatability of measurement of volume
of superior vena caval (SVC) and descending aortic (DAo) flow.
Design: SVC and DAo flow volume were assessed
four times in the first 48 h of postnatal life in a cohort of preterm
(<31 weeks) infants. Within-observer and between-observer
repeatability was assessed in a subgroup of preterm infants.
Normative values were derived from 14 preterm infants who required
<48 h respiratory support and 13 healthy term infants.
Results: Within-observer repeatability coefficient was 30
ml/kg/min for quantification of SVC flow, and 2.2 cm for DAo stroke
distance. Measurement of DAo diameter had poor repeatability.
Between-observer repeatability appeared poorer than within-observer
repeatability. The fifth centile for volume of SVC flow in healthy
preterm infants was 55 ml/kg/min and 4.5 cm for DAo stroke distance.
Conclusions: Echocardiographic assessments of volume
of SVC flow and velocity of DAo flow have similar
within-observer repeatability to other neonatal haemodynamic
measurements. Between-observer repeatability for both measurements
was poor, reflecting the difficulty of standardizing these novel
techniques. In this small cohort of preterm infants, SVC flow volume
<55 ml/kg/min and DAo stroke distance <4.5 cm represented low or
borderline systemic perfusion in the first 48 h of postnatal life.
Comments: Functional Echocardiography is becoming a valuable tool in the premises of a neonatologist especially in the diagnosis and management of shock. Evans & Kluckow group have done various observations in this regard and have strongly recommended that inotrope decision should be guided by an echocardiography especially in the first 24 hours of life. They have also shown an association between low SVC flow and IVH followed by a poor neurodevelopmental outcome at 3 years of age. Genuine doubt arises regarding the expertise of a neonatologist in performing an echo. Kluckow et al have also proposed the need for adequate training in functional echo thorugh a structured training programme. The current study confirms the above observation, and is a good article to read and add to our armamentarium. I feel the time has come to start thinking in terms of functional cardiac status and its impact on the cardiovascular hemodynamics. (VS)
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