The Paediatric Index of Mortality (PIM) is a scoring system for rating the severity of medical illness for children admitted to ICU.
PIM3 is the most recent iteration of this model.
Reference
Straney L, Clements A, Parslow RC, Pearson G, Shann F, Alexander J, et al. Paediatric Index of Mortality 3: An Updated Model for Predicting Mortality in Pediatric Intensive Care. Pediatr Crit Care Med. 2013 Jul 16: http://www.ncbi.nlm.nih.gov/pubmed/23863821