Perioperative intra- and extravascular volume in liver transplant recipients

Assessing adequate volemia to avoid fluid overload and pulmonary edema perioperatively in liver transplantation (LT) is a challenge both for the anesthetist and the intensivist. Volumetric preload indices, such as intrathoracic blood volume index (ITBVI), measured by transpulmonary thermodilution, and continuous end-diastolic volume index (EDVI), measured by pulmonary artery thermodilution, were shown to better reflect preload than central venous pressure (CVP) or pulmonary artery occlusion pressure (PAOP). An ITBVI increase soon after the graft reperfusion influenced pulmonary perfusion without an alteration of extravascular lung water index (EVLWI) and without impaired oxygenation. This study was designed to evaluate relationships between CVP, PAOP, ITBVI, EDVI, and stroke volume index (SVI) within 48 hours after LT. We also investigated the relationship between EVLWI and arterial partial pressure of oxygen and inspired oxygen fraction ratio (PaO(2)/FiO(2)).

We enrolled 125 patients (103 men and 22 women) undergoing LT. All patients were monitored with the PiCCO system (Pulsion Medical System) and with advanced pulmonary artery catheter connected to the Vigilance System. Hemodynamic-volumetric data were collected upon intensive care unit admission and every 8 hours up to 48 hours. Univariate and multivariate regression models were fitted to assess associations between SVI and EDVI, ITBVI, and filling pressures after adjusting for the right ventricular ejection fraction (RVEF, categorized as ≤30, 31-40, or >40) and the phase of the observation period. We also assessed associations between PaO(2)/FiO(2) and EVLWI.

SVI was associated with EDVI, ITBVI, and RVEF. The models showing the best fit to the data were those including EDVI and ITBVI. Neither CVP nor PAOP showed correlation with SVI. EVLWI inversely correlated with PaO(2)/FiO(2).

In the first 48 hours after LT, ITBVI and EDVI were associated with SVI assessment, whereas CVP and PAOP were not related. EVLWI significantly inversely correlated with PaO(2)/FiO(2).