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Validation of extravascular lung water measurement by transpulmonary thermodilution in a pediatric animal model
Anneliese Nusmeier1, Sabine Vrancken, Willem P de Boode
11Department of Intensive Care Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. 2Department of Pediatrics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Insights
Transpulmonary thermodilution accurately measures extravascular lung water in lambs, but overestimates it with increasing pulmonary edema. This validation is crucial for pediatric critical care.
Area of Science:
- Critical Care Medicine
- Pediatric Physiology
- Pulmonary Edema Quantification
Background:
- Extravascular lung water (EVLW) measurement via transpulmonary thermodilution (TPTD) quantifies pulmonary edema at the bedside.
- Pediatric patients exhibit higher indexed to body weight EVLW values than adults.
- TPTD validation for EVLW measurement in children is lacking.
Purpose of the Study:
- To validate TPTD for EVLW measurement in a pediatric animal model.
- To assess TPTD accuracy across a wide range of lung water volumes.
Main Methods:
- An experimental animal intervention study was conducted using eleven lambs.
- Pulmonary edema was induced via a surfactant washout model.
- EVLW index was measured using TPTD and compared with postmortem gravimetry (gold standard) and transpulmonary double indicator dilution.
Main Results:
- TPTD-derived EVLW index (EVLWITPTD) showed significant correlation with gravimetry (r=0.88) and double indicator dilution (r=0.98).
- Mean bias with gravimetry was 12.2 mL/kg (±10.9 mL/kg), and with double indicator dilution was 2.4 mL/kg (±3.8 mL/kg).
- A positive bias in EVLWITPTD increased with higher mean EVLW values, indicating overestimation in severe edema.
Conclusions:
- TPTD is significantly correlated with the postmortem gravimetric standard for EVLW measurement.
- A significant overestimation of EVLW by TPTD occurs with increasing pulmonary edema.
- Further validation is needed for precise bedside quantification in pediatric patients with edema.
Objective:
The measurement of extravascular lung water using the transpulmonary thermodilution technique enables the bedside quantification of the amount of pulmonary edema. Children have higher indexed to body weight values of extravascular lung water compared with adults. Transpulmonary thermodilution measurements of extravascular lung water in children have not yet been validated. The purpose of this study was to validate the extravascular lung water measurements with the transpulmonary thermodilution method over a wide range of lung water values in a pediatric animal model.
Design:
Experimental animal intervention study.
Setting:
Animal laboratory at the Radboud University Nijmegen, The Netherlands.
Subjects:
Eleven lambs.
Intervention:
Pulmonary edema was induced using a surfactant washout model.
Measurements And Main Results:
Between the lavages, extravascular lung water index was estimated using transpulmonary single and double indicator dilution. Two additional lambs were used to estimate extravascular lung water index in lungs without pulmonary edema. The final extravascular lung water index results were compared with the extravascular lung water index estimations by postmortem gravimetry (EVLWIG). The results were analyzed using both correlation and Bland-Altman statistics. Extravascular lung water index by transpulmonary thermodilution (EVLWITPTD) correlated significantly with either EVLWIG (r = 0.88) or with extravascular lung water index by transpulmonary double indicator dilution (EVLWITPDD) (r = 0.98). The mean bias with EVLWIG was 12.2 mL/kg (limits of agreement ± 10.9 mL/kg) and with EVLWITPDD 2.4 mL/kg (limits of agreement ± 3.8 mL/kg). The percentage errors were 41% and 14%, respectively. The bias became more positive when the mean of EVLWITPTD and EVLWIG increased (r = 0.72; p = 0.003).
Conclusions:
EVLWITPTD was significantly correlated to the postmortem gravimetric gold standard, although a significant overestimation was demonstrated with increasing pulmonary edema.
