Transcardiopulmonary thermal dye versus single thermodilution methods for assessment of intrathoracic blood volume and extravascular lung water in major burn resuscitation

Abstract

The purpose of this study was to compare the approximated values for intrathoracic blood volume (ITBV) and extravascular lung water (EVLW) obtained from a single indicator dilution to the exact data measured by double-indicator dilution. Eighteen patients with an average TBSA of 46.3% (range, 26 to 67%) and an average abbreviated burn severity index of 8.7 (range, 7 to 11) were included into a intraindividual comparative prospective study over a 20-month period. The COLD Z-021 system (Pulsion Medical Systems, Munich, Germany) was used to obtain both the exact measurements, as well as the estimated values for ITBV and EVLW. Two hundred ninety intraindividually comparative measurements were performed during the first 4 days after the burn injury. A good correlation between both techniques was shown for ITBVI (0.77; P <.01) for the overall measurements. However, the overall bias demonstrated a standard deviation higher than the mean value (-87.4 +/- 136 ml/m2), and precision for the estimated values for ITBVI was poor (-491 to 783 ml/m2). Additional analyses demonstrated a poor but significant correlation for low states of ITBV (r =.37; P <.01), but no significant correlations were found between the techniques for normal and high ITBV states. Thus, the approximated ITBV obtained from single thermodilution should not be used to guide volume therapy in major burn resuscitation. Furthermore, the EVLW is neither suitable for diagnostic use nor for therapeutic decisions because it is calculated on the basis of the poorly estimated values for ITBV in single thermodilution. Transcardiopulmonary single thermodilution is not suitable to assess intrathoracic blood volume and extravascular lung water in burn shock. However, the method is suitable to assess cardiac output and its derived parameters in burn resuscitation as shown in previous studies. It still must be proven whether the exactly measured ITBV obtained from transcardiopulmonary double-indicator dilution is superior to the commonly used parameters to guide major burn resuscitation.