In the present study simplified CPIS was used because it is simple and can be used repeatedly. This includes readily available parameters indicating clinical, laboratory and oxygenation status of patient. This score has been extensively studied in adults. This score has the sensitivity ranging from 72 - 77% and the specificity varying from 58 - 85% for the diagnosis of VAP (29, 30). The use of this score has been reported once in a retrospective pediatric study in 40 cases (31). This study showed CPIS has a PPV of 93% and was also found to be an early predictor of poor prognosis. In present study the CPIS score was also evaluated against the reference standard at values of 7, 8, 9 and 10. It was found that the most accurate value of CPIS to diagnose DEFINITE VAP was between 7 and 8 with the area under the ROC being 0.812 (p value=0.001). The mean CPIS in patients with definite VAP was 8.4 while in no definite VAP group it was 6.7 (p 0.007). In a study by Pugin et al (18), the cut off of 6 for CPIS was found to show a good correlation (r 0.84, p < 0.0001) between this clinical score and quantitative bacteriology of BAL samples.