Correlation Between Transhepatic and Subcostal Inferior Vena Cava Views to Assess Inferior Vena Cava Variation: A Pilot Study.

OBJECTIVES: To assess the feasibility and reliability of transthoracic echocardiography to measure inferior vena cava (IVC) diameter variation using a transhepatic view.

DESIGN: Prospective cohort study.

SETTING: Single-center hospital.

PATIENTS: Forty consecutive patients undergoing elective cardiac surgery.

INTERVENTIONS: Bedside transthoracic echocardiography.

MEASUREMENTS AND MAIN RESULTS: Correlation between the two views was measured using Pearson R, while agreement was measured using the intraclass correlation coefficient (ICC). In a nested sub-study of 16 randomly selected participants, all images were re-rated by the same rater, who was blinded to the original measurement results, and by a second blinded operator. Correlation between the subcostal and transhepatic views was moderate when assessing maximum (R 0.46; 95% confidence interval [CI], 0.18-0.68), and minimum (R 0.55; CI, 0.29-0.74) IVC diameter. Correlation when measuring IVC diameter variation was higher (R 0.70; CI, 0.49-0.83). Agreement between the two views for IVC diameter variation measurement was substantial (ICC 0.73; CI, 0.49-0.85). Intra-rater reliability was excellent (ICC 0.95-0.99).

CONCLUSIONS: Agreement between subcostal and transhepatic views was substantial for the assessment of IVC diameter variation; however, the magnitude of agreement was less than anticipated. Further research is needed to determine if the transhepatic view can be used reliably in the assessment of fluid responsiveness.