medwireNews: The diameter of the inferior vena cava (IVC) on ultrasound correlates strongly with central venous pressure (CVP) in neonates, research shows.
The study authors say the measurement could be used as a noninvasive method to measure right heart preload in mechanically ventilated neonates with different gestational ages and body weights.
"The veins in neonates and premature infants are particularly difficult to cannulate for CVP monitoring, with the exception of the umbilical vein, and cannulation is invasive," say Yoshiaki Sato (Nagoya University Hospital, Japan) and colleagues.
"It is therefore important to establish a noninvasive method to estimate CVP."
The researchers evaluated the maximum and minimum IVC diameter in 14 infants admitted to the neonatal intensive care unit who were fitted with a catheter to measure central venous pressure.
They found that the ratio of minimum to maximum IVC diameter significantly correlated with CVP in most of the infants upon repeated measurements.
Additionally, the authors found only a weak correlation between the diameter ratio and gestational age or birthweight when they performed the same ultrasound technique on 57 clinically stable infants with gestational ages ranging from 24 to 42 weeks, and birthweight from 620-3472 g. This indicates that the diameter ratio was almost independent of gestational age and bodyweight.
The technique has previously been validated in adults and in children but there have been few reports on the measurement of IVC in neonates, Sato and colleagues explain.
Writing in Acta Paediatrica, the authors say that the ultrasound technique provides a rapid and easy method to assess how neonates respond to interventions that affect CVP.
"Even an echocardiogram might put too much stress or strain on a sick infant," they say.
"Because the IVC is seen behind the liver, we can easily measure it even if the patient's lung is overexpanded or is being mechanically ventilated. In fact, all measurements were obtained within 2 min in this study," the authors add.
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