ORIGINAL ARTICLE

Blood flow in the common carotid artery in term and preterm infants: reproducibility and relation to cardiac output

A K Sinha, C Cane, S T Kempley

Neonatal Unit, Royal London Hospital, Whitechapel, London and Department of Child Health, Barts and the London School of Medicine and Dentistry, London, UK

Correspondence to:
Correspondence to:
Dr Sinha
Neonatal Unit, Garden House, Royal London Hospital, Whitechapel, London E1 1BB, UK; a.k.sinha{at}qmul.ac.uk

Aim: To assess the reproducibility of, and determine normative data for, flow volume measurements from the right common carotid artery (CCA) and its relation to left ventricular output (LVO) in stable term and preterm babies using Doppler ultrasound.

Methods: Right CCA flow volume was measured using a near focus, high frequency transducer by obtaining intensity weighted mean velocity and right CCA diameter. LVO was determined using standard Doppler techniques. Reproducibility studies were performed on 30 newborn infants by two observers. Normative data were obtained from 40 spontaneously breathing preterm babies and 21 term babies.

Results: The intraobserver coefficient of variation for CCA flow measurements was 10.5% for observer 1 and 15.4% for observer 2, whereas the interobserver coefficient of variation was 16.4%. In term and preterm infants, right CCA flow was about 20 ml/kg/min, accounting for 11% of cardiac output. Among the preterm infants, there was a positive correlation of right CCA flow with gestation (r = 0.61, p<0.001), weight (r = 0.64, p<0.001), and LVO (r = 0.59, p<0.001). Right CCA diameter also increased with weight (r = 0.63, p<0.001) and gestation (r = 0.58, p<0.001). The proportion of LVO distributed to the right CCA did not increase with gestation, nor did the right CCA flow per kg body weight.

Conclusions: It is possible to perform reproducible measurements of flow volume in the CCA of newborn infants. In stable, spontaneously breathing babies, both cardiac output and carotid flow increased with gestation and body weight. The proportion of cardiac output distributed to the right CCA remained relatively constant across gestation.

Abbreviations: ACABFV, anterior cerebral artery blood flow velocity; CCA, common carotid artery; LVO, left ventricular output; SVC, superior vena cava

Keywords: common carotid artery blood flow; cardiac output; Doppler ultrasound; reproducibility

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