Diagnosing invasive pulmonary aspergillosis in ICU patients: putting the puzzle together

The approach to diagnose invasive pulmonary aspergillosis in the absence of lung biopsy in ICU patients is reviewed. This approach should be based on four pillars: mycology, medical imaging, underlying conditions, and acute disease expression.

Diagnosing invasive pulmonary aspergillosis in the absence of histopathologic evidence is a matter of probability weighting. Initiating antifungal therapy in an early phase and with a lower likelihood of disease might outweigh further diagnostic workout with further delay in appropriate treatment. However, in ICU patients, a preemptive antifungal strategy has not been established yet.

For mycology, a positive galactomannan test on serum or broncho-alveolar lavage fluid is highly indicative of invasive pulmonary aspergillosis. The meaning of positive culture results, lateral-flow device test, or PCR-assay is ambiguous. A negative galactomannan or PCR test has high negative predictive value. Clinical features suggestive for invasive fungal disease on CT-scan are highly indicative but rare in ventilated patients. An immunocompromised status indicates high-risk. chronic obstructive pulmonary disease, hepatic cirrhosis, and AIDS indicate moderate risk. Invasive pulmonary aspergillosis in the absence of underlying conditions is rare. Acute diseases frequently associated with invasive pulmonary aspergillosis include sepsis and/or respiratory insufficiency because of influenza, acute respiratory distress syndrome, or pneumonia.