Using cytometric bead array (CBA) technology, we have demonstrated that IL-1b in bronchoalveolar lavage fluid (BALF) can be used to exclude VAP in both a single centre derivation study and a multi-centre validation study. A combination of IL-1b and IL-8 can exclude VAP with a sensitivity of 100%, a specificity of 44.3% and a negative predictive value of 1.