Should we elect to have our patients evaluated for VAC surveillance rather than for VAP? The fact that infection-related ventilator-associated condition is a subset of VAC might be taken to indicate that VAP is also detected by these constructs. Closer consideration of how the definitions work helps to explain why it is not a sensitive predictor of VAP. The most sensitive predictor of VAP, the presence of an infiltrate on a chest imaging study,5 and the other parameters of the Johanson et al6 criteria, are not included in the VAC construct. The sensitivity of chest imaging studies for pneumonia is the reason that most chest practitioners use this as part of their clinical evaluation. The VAC constructs are not sensitive indicators of VAPs because they do not include the criteria with the best test characteristics. Moreover, many patients with progressive deterioration of gas exchange are not detected as having VAC because they do not meet the requirement for 2 days of stable or improving ventilator settings. The Study of Knowledge of Translation of Clinical Practice Guidelines for Ventilator Associated Pneumonia (NCT00434460) has revealed that most cases of VAP in this trial were not detected by the VAC constructs, as discussed by Muscedere et al7 in this issue (see page 1453). Although the National Healthcare Safety Network (NHSN) definition of VAP is far from perfect, there is evidence that changes in practice that target known causes of pneumonia are associated with lower NHSN-defined VAP rates.8,9 Because the VAC constructs fail to detect many patients and VAP is thought to have an attributable mortality of 8%,10 failing to promote effective VAP surveillance would be expected to result in the preventable deaths of some patients. Although some might argue that a transition from VAP to VAC surveillance could reduce VAC-attributable mortality to a greater extent than the ability of current VAP prevention programs to prevent VAP-attributable mortality, others may believe that failing to avert preventable mortality is unacceptable.