[Extended hemodynamic monitoring using transpulmonary thermodilution Influence of various factors on the accuracy of the estimation of intrathoracic blood volume and extravascular lung water in critically ill patients].

BACKGROUND: The transpulmonary thermal-dye dilution (TDD) is the clinical gold standard for measurement of intrathoracic blood volume (ITBV) and extravascular lung water (EVLW). Recently, experimental and clinical studies found that ITBV and EVLW can be derived reliably by single transpulmonary thermodilution (TD), however, dependency from various factors of lung function has been discussed. PATIENTS AND METHODS: We retrospectively analyzed data from 174 critically ill patients who had undergone hemodynamic monitoring by TDD. We calculated the differences of simultaneous TD and TDD determined by ITBV or EVLW measurements. Bias and standard deviations (SD) were calculated and extended Bland-Altman regression analyses were performed. Association of the differences and the potential confounders gender, age, PEEP, p(a)O(2)/F(I)O(2) ratio and the corresponding TDD measurement were analyzed by multiple linear regression and LOWESS regression.
RESULTS: Overall results (bias+/-SD) were 1+/-58 ml/m(2) for ITBV and 0.0+/-1.4 ml/kg bw for EVLW, but TD overestimated TDD results in patients with higher ITBV and underestimated those for lower ITBV values. The deviations were small, and the dependence of ITBV could be explained completely by dependence on PEEP and age. However, low values of EVLW are overestimated by TD.
CONCLUSION: Single transpulmonary thermodilution for estimation of ITBV or EVLW is reliable in patients with severe lung injury for normal and higher values.