Introduction PRISM score (Paediatric risk mortality) is widely used to determine the risk of mortality in children in PICU. Recent studies had found correlation between the low values of PRISM with the success of noninvasive ventilation (NIV) and the high values with failure, but without clearly defined who will be called higher or lower value of PRISM score.

Objective To evaluate the predictive value of PRISM score for NIV success in acute respiratory failure (ARF).

Methods This is a prospective study. Are included all children admitted at PICU during January–December 2011. NIV was used as the primary support for ARF. We analysed the predictive value of the PRISM score using ROC curves and the trend of success change by Chi-square trend.

Results A total of 42 patients were included. NIV success rate was 73.8%. Prism score in the success group was 9.5 ± 3.9 vs. 14.5 ± 6.6 points in the failure group (p = 0.0184). Max value was 27 points, min value 3 points. By ROC curves, PRISM < 10 points before NIV results significant predictive factor for NIV success with predictive positive value 87.5%. By Chi-square trend it was found a significant trend of success reduction with increasing value of PRISM. For PRISM score = 10 up to 15 points, OR = 0.3 (95% CI 0.05–2.0) p = 0.2. For PRISM score >15 points, OR = 0.08 (95% CI 0.01–0.5) p = 0.01. (χ² _{for linear trend} = 7.6, p < 0.01).

Conclusion PRISM score <10 points is a significant predictive factor for NIV success. For PRISM score >15 points the likelihood to have success is decreased significantly.