A within-trial cost analysis will be undertaken to assess the impact of biomarker-based guidance of VAP management on hospital resource use from the point of randomisation until hospital discharge or death, whichever occurs first, for a maximum of 56 days. Patient-level hospital resource use will be estimated from length of ICU stay and length of hospital stay. Mean hospital resource use and associated costs will be estimated for the intervention and standard care groups and compared. Multiple regression analyses will be performed to examine patient factors which are potentially associated with costs. Robustness of results will be evaluated using sensitivity analyses.