Aspiration in a specialised weaning unit--an underestimated problem

Abstract

This retrospective case series shows that 45 % of patients aspirated straight after removal of the tracheal cannula. The present case series includes 82 patients with long-term mechanical ventilation (LTMV) admitted to a specialised weaning unit. Aspiration was proven after patients sipped water coloured with patent blue V. Colour was detected with a bronchoscope after passing through the tracheostoma and directed toward the VC. The aspiration rate in this study is in good agreement with other reports in the literature.We could find no significant statistical differences concerning age (p = 0.97), gender (47 % vs. 49), number of bronchoscopies (p = 0.91) and comorbidities (p = 0.326) between patients with and without aspiration. The duration of the stay at the ward and the duration of ventilation as well as the parameter Hb at the time of admission (p = 0.566), CO2(p = 0.288/p = 0.716), HCO3 (p = 0.915/p = 0.612) and CRP (p = 0.402/p = 0.523) at the time of admission and discharge also showed no significant differences.The Kaplan Meier curves show a considerable divergence between patients with and without aspiration. However, the Log Rank Test (p = 0.348) and the univariate Cox Regression (HR 1.4, 95 % CI 0.689 - 2.849) were not significant. We believe that this can be attributed to the event rate, which was too low in our collective. This trend to a higher mortality of patients with aspiration might be due to weakness of the respiratory muscles when there is reduced coughing. Proof of aspiration in these patients is only one aspect of a multidimensional problem. Larger, prospective cohort studies are needed to show whether aspiration can serve as a prognostic marker.