The Inferior Vena Cava Collapsibility Index as a Non-Invasive Haemodynamic Tool in Mechanically Ventilated Surgical...

Background/Objectives: Hypovolaemia and hypotension in the postoperative neonatal period are life-threatening conditions difficult to diagnose with standard clinical parameters. The inferior vena cava collapsibility index (IVCCI) is a validated non-invasive tool in adults; its application in mechanically ventilated surgical neonates remains poorly defined. This study aimed to evaluate the association of the IVCCI with echocardiographic haemodynamic indices and its changes following volume expansion in surgically treated neonates. Methods: This monocentric observational study enrolled 36 surgical neonates (mean gestational age 38.1 weeks; mean weight 2799 g) with postoperative hypovolaemia and oliguria at the UOC NICU-Neonatology, AOU Policlinico G. Rodolico-San Marco, Catania (July 2020-September 2023). All patients were on controlled invasive mechanical ventilation. The IVCCI, cardiac output (CO), stroke volume (SV), and peak Doppler velocities (Vmax) of the pulmonary artery and aorta were measured before and 4-6 h after colloid infusion (10-20 mL/kg). Results: The IVCCI decreased significantly from 44.05 ± 7.8% to 15.14 ± 4.3% (p < 0.001). MAP improved from 36.89 ± 5.12 to 55.99 ± 4.87 mmHg (p < 0.001) and pH from 7.32 ± 0.04 to 7.36 ± 0.03 (p < 0.01). The Vmax, SV, and CO of both ventricles increased significantly (all p < 0.001). Significant inverse correlations were found between the IVCCI and MAP, Vmax, CO, and SV (all p < 0.001). No correlation was found with gestational age, birth weight, or pain scores. Conclusions: The IVCCI is a feasible and clinically useful non-invasive echocardiographic parameter for haemodynamic monitoring in critically ill surgical neonates. Its significant correlation with cardiac function indices supports its potential role in the bedside assessment of suspected hypovolaemia. Larger prospective studies are warranted.