The standard of care of patients with ARDS: ventilatory settings and rescue therapies for refractory hypoxemia

Bein, Thomas; Grasso, Salvatore; Moerer, Onnen; Quintel, Michael; Guerin, Claude; Deja, Maria; Brondani, Anita; Mehta, Sangeeta

Tracheobronchial secretion should be investigated using quantitative BAL (100-120 ml 0.9 % NaCl) or mini-non-bronchoscopic BAL (20-40 ml 0.9 % NaCl), especially in (hypoxemic) situations were bronchoscopyguided BAL might be too invasive [63] . The cutoff for significant number of colony forming units to differentiate between colonization and infection depends on the diagnostic test: tracheobronchial secretion, 10-5 CFU/ ml; BAL, 10-4 CFU/ml; and protected specimen brush, 10-3 CFU/ml [64] . Gram-staining is still recommended, since in patients without anti-infective treatment a high negative predictive value is documented. For exclusion of atypical pneumonia, Legionella antigen assessment (urine, sputum) with two negative tests is recommended. New molecular assays as part of a panel for viral pneumonia (influenza A with two subtypes, parainfluenza 1-4) and atypical pathogens with a short run time are available. In ICU patients with influenza-associated pneumonia at risk for bacterial co-infections, a 5-day delay for treatment of seasonal influenza and influenza-associated infection is reported (Table 3 ) [65] . Of note careful examination may help to exclude some clinical entities that are mistaken for ARDS (e.g., idiopathic pulmonary fibrosis, cryptogenic organizing pneumonia, nonspecific interstitial pneumonitis, Wegener's granulomatosis, or acute eosinophilic pneumonia). These diseases need of course a lung-protective strategy (limitation of V T ), but some other ARDS-specific measures as addressed in this article are not proven and may not be "automatically" helpful [66, 67] . Various diagnostic tools of BAL analysis (hemogram, cytology, and flow cytometric analysis) have been described as a complete diagnostic workup [68] . In immunosuppressed patients specific diagnostic and therapeutic procedures are essential. Pretreatment with antiinfectives, local resistance, and severity of illness with organ failure have to be considered for calculated use of broad-spectrum antibiotics [69] . Targeted treatment after successful detection of the responsible pathogen is more effective and lowers mortality. Moreover, de-escalation and targeted anti-infective treatment of pneumonia reduce superinfection with resistant pathogens.