Preload index: pulmonary artery occlusion pressure versus intrathoracic blood volume monitoring during lung transplantation

In this study, during lung transplantation, we analyzed a conventional preload index, the pulmonary artery occlusion pressure (PAOP), and a new preload index, the intrathoracic blood volume index (ITBVI), derived from the single-indicator transpulmonary dilution technique (PiCCO System), with respect to stroke volume index (SVIpa). We also evaluated the relationships between changes () in ITBVI and PAOP and SVIpa during lung transplantation. The reproducibility and precision of all cardiac index measurements obtained with the transpulmonary single-indicator dilution tech- nique (CIart) and with the pulmonary artery thermodilution technique (CIpa) were also determined. Measurements were made in 50 patients monitored with a pulmonary artery catheter and with a PiCCO System at six stages throughout the study. Changes in the variables were calculated by subtracting the first from the second measurement (1 ) and so on (1 to 5 ). The linear correlation between ITBVI and SVIpa was significant (r20.41; P 0.0001), whereas PAOP poorly correlated with SVIpa (r2 0.01). Changes in ITBVI correlated with changes in SVIpa (1, r2 0.30; 2, r2 0.57; 4, r2 0.26; and 5, r2 0.67), whereas PAOP failed. The mean bias between CIart and CIpa was 0.15 l · min 1 · m 2 (1.37). In conclusion, ITBVI is a valid indicator of cardiac preload and may be superior to PAOP in patients undergoing lung transplantation.