Respiratory variation of inferior vena cava diameter and central venous pressure in ventilated and non-ventilated children in fluid refractory septic shock: an observational study

Background: Ultrasound guided fluid assessment in management of septic shock has come up as an adjunct to the current gold standard Central Venous Pressure monitoring. This study was designed to observe the respiro-phasic variation of IVC diameter (RV-IVCD) in invasively mechanically ventilated and spontaneously breathing paediatric patients of fluid refractory septic shock.Methods: This was a prospective observational study done at Paediatric intensive Care Unit (PICU) in Paediatric ward of Jawaharlal Nehru Medical College and Hospital (JNMCH) from February 2016 to June 2017. 107 consecutive patients between 1 year to 16 years age who were in shock despite 40ml/kg of fluid administration were included. Inferior Vena Cava (IVC) diameters were measured at end-expiration and end inspiration and the IVC collapsibility index was calculated. Simultaneously Central Venous Pressure (CVP) was recorded. Both values were obtained in ventilated and non-ventilated patients. Data was analysed to determine to look for the profile of RV-IVCD and CVP in ventilated and non-ventilated cases.Results: Out of 107 patients, 91 were on invasive mechanical ventilation and 16 patients were spontaneously breathing. There was a strong negative correlation between central venous pressure (CVP) and inferior vena cava collapsibility (RV-IVCD) in both spontaneously breathing (-0.810) and mechanically ventilated patients (-0.700). Negative correlation was significant in both study groups in CVP <8 mmHg and only in spontaneously breathing patients in CVP 8-12 mmHg range. IVC collapsibility showed a decreasing trend with rising CVP in both spontaneously breathing and mechanically ventilated patients.Conclusion: Ultrasonography guided IVCCI appears to be a valuable index in assessing fluid status in both spontaneously breathing and mechanically ventilated septic shock patients. However, more data is required from the paediatric population so as to define it as standard of practice.