Non-invasive Assessment of Significant Dehydration in Infants Using the Inferior Vena Cava to Aortic Ratio: Is it Useful?

OBJECTIVES: The aim of the study was to assess the accuracy of the inferior vena cava to aorta (IVC/Ao) diameter ratio for predicting significant dehydration in infants relative to their percentage weight change and the clinical diagnosis by a physician.

METHODS: A prospective observational study was performed on 200 infants presented with acute diarrhea and clinical evidence of significant dehydration whose treatment required intravenous (IV) fluids as determined by the attending physician at the pediatric emergency department of Tanta University Hospital. Weight was recorded at admission before IV fluid treatment and at hospital discharge. The percentage of dehydration was determined using the following formula: (discharge weight - admission weight)/discharge weight × 100%. Patients with a percentage weight change of <5% were considered to be nonsignificantly dehydrated, whereas patients with a percentage weight change >5% were considered significantly dehydrated. The IVC/Ao diameter ratio was measured for all patients before IV fluid rehydration and again at discharge.

RESULTS: Only 134 out of 200 dehydrated infants were found to be significantly dehydrated using the gold standard, percentage weight change. Receiver operating characteristics (ROC) curve analysis of the prehydration IVC/Ao ratio showed a sensitivity of 82%, a specificity of 91%, and an accuracy of 87% for predicting significant dehydration in infants at a cut-off point of less than 0.75. In contrast, physician clinical diagnosis showed a sensitivity of 70%, a specificity of 63%, and an accuracy of 73%.

CONCLUSIONS: The IVC/Ao diameter ratio can be used as a reliable predictor for diagnosing significant dehydration in infants.