 Objectives: The goal of the Pediatric OPALS Study is to evaluate the benefit of introducing a prehospital program of full ALS measures intubation and intravenous drug therapy on the outcomes of critically ill and injured pediatric patients. Specific objectives are to determine the impact of this ALS program on mortality, other clinical outcomes, morbidity quality of life, EMS response intervals, and cost-effectiveness for these critical conditions: a Respiratory distress and obstruction, b Seizure, c Major trauma, and d Cardio-pulmonary arrest. We hypothesize, for each of the four patient populations separately, that in the Intervention period: i Mortality will be reduced primary hypothesis; ii Other Clinical Measures will be improved for other clinical outcomes, ED interventions, admission rates, and lengths of stay; iii Quality of Life of survivors will be improved for both generic and disease-specific measures; iv Response Time Intervals will not be increased; and, v Economic Evaluation will reveal that the costs and effects are distributed more favourably. 