Bronchoalveolar lavage with a diluted surfactant suspension prior to surfactant instillation improves the effectiveness of surfactant therapy in experimental acute respiratory distress syndrome (ARDS).

Abstract

To assess whether bronchoalveolar lavage (BAL) with a diluted surfactant suspension prior to surfactant instillation prevents the only transient improvement in lung function as reported after surfactant instillation in severe acute respiratory distress syndrome (ARDS). Randomized, prospective, experimental study. Laboratory and animal facility of a large university. Adult male Sprague-Dawley rats (280 +/- 30 g). All animals underwent repetitive whole lung saline lavage to induce acute lung injury. Then, animals were randomly divided into seven study groups: the first group received surfactant (150 mg/ kg) within 10 min after the last lavage (early treatment), whereas in the other six groups mechanical ventilation was continued for 3 h before treatment (late treatment). Treatment consisted of: surfactant instillation at a dose of 150 mg/kg; at a dose of 250 mg/kg; BAL with saline; BAL with a diluted surfactant suspension (2.5 mg/ml); BAL with saline, immediately followed by surfactant instillation (150 mg/kg) and BAL with a diluted surfactant suspension (2.5 mg/kg), immediately followed by surfactant instillation (150 mg/kg). Blood gases were measured for 6 h and then BAL was performed to measure the protein concentration and surface tension properties. Mean PaO2 values increased immediately after surfactant instillation to pre-lavage 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. BAL with a diluted surfactant suspension prior to surfactant instillation at a later time point in lung injury resulted in a stable improvement of lung function. This improvement is comparable with the results seen after surfactant instillation immediately after lung lavage.