BRONCHOALVEOLAR LAVAGE WITH A DILUTED SURFACTANT SUSPENSION PRIOR TO SURFACTANT INSTILLATION IMPROVES THE EFFECTIVENESS OF SURFACTANT THERAPY IN EXPERIMENTAL ACUTE RESPIRATORY-DISTRESS SYNDROME (ARDS)

Objective:To assess whether bronchoalveolar lavage (BAL) with a dilute d surfactant suspension prior to surfactant instillation prevents the only transient improvement in lung function as reported after surfacta nt instillation in severe acute respiratory distress syndrome (ARDS). Design: Randomized, prospective, experimental study. Setting: Laborato ry and animal facility of a Large university. Materials.-Adult male Sp rague-Dawley rats (280 +/- 30 g). Interventions: All animals underwent repetitive whole lung saline lavage to induce acute lung injury Then, animals were randomly divided into seven study groups: the first grou p received surfactant (150 mg/kg) within 10 min after the last lavage (early treatment) whereas in the other six groups mechanical ventilati on was continued for 3 h before treatment (late treatment). Treatment consisted of: surfactant instillation at a dose of 150 mg/kg; at a dos e of 250 mg/kg: BAL with saline; BAL with a diluted surfactant suspens ion (2.5 mg/ml); BAL with saline. immediately followed by surfactant i nstillation (150 mg/kg) and BAL with a diluted surfactant suspension ( 2.5 mg/kg), immediately followed by surfactant instillation (150 mg/kg ). Measurements and results: Blood gases were measured for 6 h and the n BAL was performed to measure the protein concentration and surface t ension properties. Mean PaO2 values increased immediately after surfac tant instillation to prelavage values but remained stable only in the group that received surfactant immediately after the lavage procedure and the group that underwent BAL with a diluted surfactant suspension prior to surfactant: instillation. Conclusion: BAL with a diluted surf actant suspension prior to surfactant instillation at a later time poi nt in lung injury resulted in a stable improvement of lung function, T his improvement is comparable with the results seen after surfactant i nstillation immediately after lung lavage.