1. Infectious causes of persistence of MODS have reasonably been ruled out on clinical or other grounds (infectious endocarditis, undrained abscesses like sinusitis, empyema or abdominal pus). Consider sampling for culture of broncho-alveolar lavage fluid, protected specimen brush or other (empyema fluid, lung tissue) in order to rule out respiratory infection, as well as intra-vascular catheter change and culture.