OPALS Critical Care Sub-Studies

Inclusion Criteria: * Chest Pain Sub-Study: Adult patients with a complaint of chest pain of an acute nature transported to hospital by ambulance. Patients with a complaint of pain in arms, neck or jaw if consistent with myocardial ischemia. Patients must have an ambulance return code of prompt, urgent, or no patient carried. * Respiratory Sub-Study: Adult patients with a chief complaint of shortness of breath defined as ACR codes of Respiratory Failure, Shortness of Breath NYD, Pulmonary Edema (CHF), Asthma and had either prehospital assisted ventilation or abnormal respiratory rates (\>=24 or \<=10) * Major Trauma Sub-Study: Adult patients who have suffered an injury from any mechanism with an Injury Severity Score of \>12 who have been transported to hospital by land ambulance, and who have been entered into the Ontario Trauma Registry (OTR) Comprehensive Data Set. Exclusion Criteria: * All Sub-Studies: * Patients under the age of 16 * Patients who are vital signs absent prior to EMS arrival. * Chest Pain Sub-Study: * Patients suffering primarily from respiratory distress, respiratory failure, pulmonary edema, asthma, palpitations or epigastric pain. pain