Intrathoracic Blood Volume as an End Point in Resuscitation of the Severely Burned: An Observational Study of 24 Patients

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Abstract
Treatment of burn shock according to empirical resuscitation formulas is still considered the gold standard, and the burn community does not advocate the use of invasive cardiorespiratory monitoring in general. As a consequence, data dealing with early postburn hemodynamics are sparse, and only few studies have paid attention to the topic of end-point burn shock resuscitation. However, recent studies have suggested that burn survival may be improved when invasive monitoring is used to guide fluid therapy during the shock phase. In an observational study of 24 patients with severe burns, the transpulmonary double indicator dilution technique was used for semi-invasive hemodynamic monitoring. The clinical utility of the intrathoracic blood volume (ITBV) as an end-point variable for fluid resuscitation was evaluated, comparing correlation of filling pressure obtained by a pulmonary artery catheter and intrathoracic blood volume to cardiac index and oxygen delivery. In addition fluid volume predicted by the Parkland burn formula was compared with the actual fluid volume given when ITBV was used as end point for resuscitation. ITBV-guided resuscitation was associated with restoration of preload and peripheral delivery of oxygen within 24 hours in the majority of patients. Augmentation of ITBV was significantly correlated with changes in cardiac index and oxygen transport rate. No such correlation could be demonstrated for the conventional preload parameters such as central venous pressure and pulmonary capillary wedge pressure. Thus, ITBV seemed in burned, hypovolemic patients a better indicator of the preload component of the cardiac output than the conventional preload parameters obtained with the pulmonary artery catheter. Significantly larger volumes of crystalloids than predicted by the Parkland formula were administered when ITBV was used as end point for resuscitation. The extravascular lung water remained normal during this extraordinary high volume load. ITBV may be a reliable preload indicator to guide volume therapy in life-threatening burns, and end-point-fixed resuscitation to this parameter seems to be associated with significantly higher fluid administration than calculated compared with traditional burn formulas. The effects of burn resuscitation to fixed end points on survival and multiple organ failure should be evaluated in future randomly assigned trials.