The relationship between collapsibility index of inferior vena cava and hypotension after spinal anesthesia

Objectives: Hypotension is a common complication of spinal anesthesia. Imaging of inferior vena cava (IVC) and measurement of the IVC-collapsibility index (IVC-CI) by ultrasonography (USG) has been a widely used non-invasive, easy and reliable method for measurement of the fluid imbalance. In the present study, we aimed to investigate the predictive ability of the maximum IVC diameter (dIVCmax) and IVC-CI for hypotension after spinal anesthesia. Methods: The study was designed as prospective and observational. One hundred thirty-two patients aged 18-75 years with ASA I-II underwent inguinal hernia surgery with spinal anesthesia and recruited to the study. Maximum and minimum (dIVCmin) IVC diameters were measured. IVC-CI (%) was quantified according to the formula of [(dIVCmax - dIVCmin)/dIVKmax] × 100%. Results: The patients were grouped as hypotensive and non-hypotensive. In fifty-seven patients of 120 cases (47.5%), hypotension has emerged following spinal anesthesia. No significant differences in dIVCmax and IVC-CI were recorded between the study groups (p > 0.05). There were significant inverse correlation between age and IVC-CI. Significant positive correlation between the lowest values of the systolic arterial pressure, diastolic arterial pressure, mean arterial pressure and IVC-CI and significant positive correlation between dIVCmax and diastolic blood pressure, maximum and minimum values of the mean arterial pressure. Conclusions: We found that dIVCmax and IVC-CI values measured before spinal anesthesia were not sufficient parameters enough to predict hypotension after spinal anesthesia. Further studies investigating the IVC measurements under spinal anesthesia together with dynamic hemodynamic monitorization modalities are needed.