Accuracy of the double indicator method for measurement of extravascular lung water depends on the type of acute lung injury.

Abstract

OBJECTIVE:

The double indicator method is sensitive to alterations in the distribution of pulmonary blood flow. This distribution is influenced by the type of lung injury. The aim of this study was to compare measurements of lung water by the double indicator method with measurements obtained by gravimetry in a direct lung injury model induced by tracheal instillation of hydrochloric acid and in an indirect lung injury model induced by the intravenous injection of oleic acid.

DESIGN:

Prospective, randomized laboratory study.

SETTING:

Animal research laboratory.

SUBJECTS:

Forty-two female pigs (28+/-3 kg).

INTERVENTIONS:

Pigs were anesthetized and ventilated and were allocated into three groups: control (n = 6), hydrochloric acid (4 mL/kg intratracheally, n = 24), or oleic acid (0.1 mL/kg intravenously, n = 12).

MEASUREMENTS AND MAIN RESULTS:

Hydrochloric acid instillation or oleic acid injection resulted in a similar hypoxemia and induced a two- to three-fold increase in extravascular lung water (EVLW) by gravimetry (EVLWG) at 3 hrs compared with controls. In the oleic acid group, there was a significant correlation between EVLWG and EVLW by double indicator method (EVLWDI; r =.88, p <.0001). The bias for EVLWDI - EVLWG measurements was -5.2 mL/kg (95% confidence interval, -5.7 to -4.7 mL/kg) with 95% limits of agreement of -7 to -3.4 mL/kg. In the hydrochloric acid group, there was no significant correlation between EVLWDI and EVLWG values, and the double indicator method failed to detect pulmonary edema in 65% of the animals (EVLWDI <8 mL/kg). The bias was -7.9 mL/kg (95% confidence interval, -9.3 to -6.5 mL/kg) with 95% limits of agreement of -14.4 to -1.4 mL/kg.

CONCLUSIONS:

The double indicator method is useful for evaluation of pulmonary edema in indirect lung injury, as induced by oleic acid, but produces misleading values in direct lung injury, as produced by hydrochloric instillation.

• Authors: Antoine Roch, Pierre Michelet, Dominique Lambert, Stéphane Delliaux, Christophe Saby, Gilles Perrin, Olivier Ghez, Fabienne Bregeon, Pascal Thomas, Jean-Pierre Carpentier, Laurent Papazian, Jean-Pierre Auffray
• Journal: Critical care medicine (Crit Care Med) Vol. 32 Issue 3 Pg. 811-7 (Mar 2004) ISSN: 0090-3493 [Print] United States
• PMID: 15090967 (Publication Type: Comparative Study, Evaluation Study, Journal Article)

Chemical References

• Oleic Acid
• Hydrochloric Acid

Topics

• Analysis of Variance
• Animals
• Disease Models, Animal
• Extravascular Lung Water (metabolism)
• Female
• Hemodynamics
• Hydrochloric Acid (administration & dosage)
• Indicator Dilution Techniques
• Oleic Acid (administration & dosage)
• Prognosis
• Prospective Studies
• Pulmonary Edema (diagnosis, etiology, pathology)
• Random Allocation
• Respiratory Distress Syndrome (diagnosis, etiology, pathology)
• Respiratory Mechanics
• Swine