Hypovolemia assessment with inferior vena cava collapsibility index in cardiac surgery patients: a cross-sectional study.

backgroundPatients who undergo cardiac surgery are at high risk of developing hemodynamic instability during induction of anesthesia, with hypovolemia being a possible trigger. The diagnosis of this condition usually depends on the anesthesiologist’s clinical judgment and ability to interpret hemodynamic parameters once induction has begun. Assessment of inferior vena cava collapsibility and diameter has been correlated with identification of patient volume status. The aim of this study was to describe hemodynamic behavior during anesthetic induction based on the presence of hypovolemia, assessed with the inferior vena cava collapsibility index (IVCCI), in patients who underwent coronary artery bypass grafting (CABG) surgery or aortic valve replacement (AVR).

methodsThis descriptive cross-sectional study included the sequential sampling of 60 adult patients programmed for CABG or AVR between July 2022 and January 2023. Patients with reduced ejection fraction (< 40%), a history of liver disease, ascites, cardiac arrhythmias, abdominal hypertension and a body mass index > 35 kg/m2 were excluded. The IVCCI was measured via ultrasonography and calculated using a specific formula, with hypovolemia defined as an IVCCI greater than 30%. Demographic data, echocardiographic measurements, hemodynamic variables (respiratory rate, blood pressure, heart rate) were extracted, and the IVCCI was calculated. Variables were analyzed via JASP v 0.17.1.

resultsAmong the 60 patients who were included, 40 underwent CABG, and 20 underwent AVR. 67% (n = 40) of the sample developed hypovolemia, with no significant difference between the CABG and AVR groups. The mean IVCCI was 32.7 (95% CI: 30.5–34.8) for CABG and 29.33 (95% CI: 25.6–33.0) for AVR. No significant difference in hemodynamic changes was found between the groups classified by volume status. Moreover, an exploratory analysis of the impact of fasting on the risk of developing hypovolemia revealed a Pearson correlation coefficient that was weak but positive (0.20) among these variables.

conclusionsThis study showed no significant changes in hemodynamic behavior in the evaluated patients prior to, during, or after anesthetic induction with an IVCCI cut-off value of 30%. Similarly, a slight positive correlation was observed between fasting and hypovolemia, although it lacked statistical significance.