Reproducibility of transpulmonary thermodilution measurements in patients with burn shock and hypothermia.

Thermal noise, including hypothermia and short-term variations in body temperature, has been reported to influence the accuracy and reproducibility of thermodilution measurements. This variation might theoretically limit the usefulness of this technique in patients with acute burns. We therefore sought to determine the reproducibility of hemodynamic parameters derived from arterial thermal dilution in patients with acute burns and hypothermia. This was a prospective, clinical study of 50 mechanically ventilated patients with burns involving more than 25% of the body surface area that were treated at an eight-bed intensive care burn unit in a university-affiliated hospital. A total of 750 arterial thermodilution measurements were analyzed using the COLD system. Triplicate measurements of the intrathoracic blood volume, cardiac output, total blood volume, and extravascular lung water were performed at regular intervals during the first 48 hours after the thermal injury. Reproducibility was assessed by the coefficient of variation of the triplicate measurements. The correlation of variation was less than 10% at all measurement times for cardiac output, intrathoracic blood volume, and total blood volume. For the extravascular lung water, the coefficient of variation ranged from 9.5% to 12.9%. A maximum of 12.9% was found at 48 hours after burn. No correlation was found between body core temperature and the reproducibility of intrathoracic blood volume index (r = 0.145), cardiac index (r = 0.217), or extravascular lung water index (r = 0.167). The parameters derived from arterial thermodilution show a clinically sufficient reproducibility in patients with acute burns associated with thermal instability.

Effect of crystalloid resuscitation and inhalation injury on extravascular lung water: clinical implications.

STUDY OBJECTIVE: Arterial thermal dilution with an integrated fiberoptic monitoring system (COLD Z-021; Pulsion Medical Systems; Munich, Germany) allows measurement of extravascular lung water (EVLW) and pulmonary permeability index (PPI). The aim of this study was to evaluate the widespread clinical assumption that early respiratory failure following burn and inhalation injury is due to interstitial fluid accumulation in the lung. DESIGN: Clinical, prospective study. SETTING: ICU of a university referral center of burn care. PATIENTS: Thirty-five severely burned adults (> 20% of body surface area). INTERVENTIONS: Resuscitation therapy was guided by the results of hemodynamic monitoring using the intrathoracic blood volume (ITBV) as a cardiac preload indicator. The resuscitation goals included a normalization of preload (ITBV > 850 mL/m(2)) and cardiac index (> 3.5 L/min/m(2)) within 24 h after ICU admission. Fluid loading was implemented to reach these goals. MEASUREMENTS AND RESULTS: One hundred forty lung water measurements were performed at 0 h, 12 h, 24 h, and 48 h after admission to the ICU. Significant elevation of EVLW and PPI was found in three measurements (2%) at 48 h after ICU admission, and was in one patient associated with inhalation injury. EVLW and PPI were not significantly different between patients with and without inhalation injury. No correlation was found between resuscitation volume and EVLW (r(2) = 0.02) or between the alveolar-arterial oxygen pressure difference and EVLW (r(2) = 0.017). Chest radiograph abnormalities were found in 2 of 22 patients with inhalation injury; these were not associated with increased values of EVLW. CONCLUSION: Early fluid accumulation in the lung in burned patients is very uncommon, even in the presence of inhalation injury. There is no evidence that thermal injury causes an increase in pulmonary capillary membrane permeability.