Correlation of ultrasound measurement of IVC to aorta diameter ratio with hematocrit and shock severity among children with dengue fever

Abstract

Background: Severe dengue is a leading cause of serious illness and death, particularly in the Philippines. There is no specific treatment for dengue fever. Before fluid resuscitation, a baseline hematocrit is obtained, and frequent monitoring of the complete blood count is needed depending on the case of the patient. Aside from obtaining the hematocrit, the IVC/Ao diameter ratio can be a promising tool in objectively guiding the clinicians during the fluid resuscitation in real-time. This study aims to determine the correlation of ultrasound measurement of IVC to aorta diameter ratio with hematocrit and severity of shock among children with dengue fever seen at the emergency room. Methods and materials: This is a prospective observational study design that was conducted at the ER of a tertiary hospital. Clinical data and hematocrit of the children with dengue fever aged 1 m to 18 y old were documented. The Inferior vena cava diameter (IVC)and the Aorta (Ao) diameter ratio was determined using bedside ultrasound. Results: The IVC/Ao diameter ratio correlates with high hematocrit and dengue shock in children (p < 0.0001). There is a significantly higher proportion of subjects with a hematocrit of normal range of age among those with a ratio 1.0. A ratio of <0.8 is significantly associated with high hematocrit level for age (p < 0.0001). Overall, IVC/Ao diameter ratio was significantly associated with severity of Dengue illness. 97% of those without warning signs had IVC/Ao diameter ratio of 1.00 (p < 0.0001). For those with warning signs, 63.4% had a ratio of from 0.8–0.99, and 93% with severe dengue had a ratio of from <0.80 (p < 0.0001). Sensitivity or the probability of identifying those with true disease, of IVC/Ao diameter ratio of <1.00 in predicting dengue with warning signs and severe dengue (grouped) was 87.7%. Specificity or the probability of identifying those without the disease (without warning signs) was higher at 97.1%. Measurement of IVC/Ao diameter ratio has high interrater and intrarater reliability. Conclusion: This study concludes that the IVC/Ao ratio correlates with the severity of dengue fever and with the hematocrit in the emergency setting. Overall, IVC/Ao diameter ratio was significantly associated with severity of dengue illness.