Ventilator-associated sinusitis : a clinical investigation into the inflammatory response : reactive – infective – infectious?

Abstract

Critically ill mechanically ventilated patients regularly have inflammatory reactions in the paranasal sinuses. Infectious sinusitis, which is difficult to diagnose, may occur, mainly in the maxillary sinuses. This study was performed with the object of improving the knowledge of inflammatory and/or infectious disease. Ultrasound, as an indirect diagnostic facility, was evaluated against visual criteria at endoscopy. Assessments by endoscopy were calibrated with the help of video recordings evaluated by an expert panel. To improve bacteriological diagnostics of the antra a new technique for sampling was developed to reduce contaminations. A routine was set up to identify false positive cultures by comparative quantitative cultures from the antra and the corresponding passage route. Anaerobic cultures from antral mucosa were made. Correlations between endoscopic and bacteriologic diagnostics were analysed. To find out if antibiotics used in the ICU reach the antra, concentrations were determined by a bio-assay method. As markers of inflammatory diseased antral mucosa, the cytokines lL-6, IL- 12 and the chemokine RANTES were determined by RT-PCR. The expression of the adhesion molecules ICAM-1, VCAM-I, E- and P-selectin was demonstrated by immunocytochemistry.

Ultrasound had a low capacity for differential diagnostics. The expert panel verified the reliability of endoscopic assessments. There was an almost perfect concordance on infectious sinusitis. The endoscopic diagnosis of infectious sinusitis correlated to positive anaerobic cultures. The rate of false positive cultures was significantly reduced by the improved sampling technique. Three antra, with positive cultures, were assessed endoscopically as inflammatory reaction without signs of infection. They were thus colonised. The bacterial findings were mostly anaerobic or facultative anaerobic. The most common pathogens, as previously described, Staphylococcus aureus and Pseudomonas aeruginosa, were only present in gingival cultures or as contaminants but not identified as the cause of infection. Different stages of inflammatory disease were found in 85%. But only 6% (4 antra) were infectious Sinusitis. Lactobacillus were monoisolates in 2 out of 3 colonisations. In all infected or colonised antra, mRNA of RANTES was found (p= 0.005). The predominant adhesion molecule expressed in all specimens examined was P-selectin. The antibiotic concentrations in intracellular tissue were related to the serum levels and thus strongly support an appropriate localisation of the drugs included. The four infections diagnosed were empyema as with retained secretion constituting biofilm formations where the bacteria were inaccessible to antibiotics. In summary, the rate of infectious sinusitis was markedly less in this study compared to previous publications. The main pathogens of the infections diagnosed also differed. Antral colonisation of bacteria, regarded as nonpathogenic, has not been reported in mechanically ventilated patients previously.