This is a retrospective project. Data will be used from Quality Improvement database for publication purpose. Data was collected from a prospectively collected database that was done as a Quality Improvement Project. The study sites included post anesthesia care units (PACU) of the main and ambulatory campuses of our hospital. The data was collected from surgical and radiology PACU's. Data was collected each quarter for 2 weeks in the surgical PACU, and for 1 month in Radiology PACU, from Sep 2007 through Mar 2012. Trained perioperative nurses and Certified Registered Nurse Anesthesiologist did data collection. This ensured a sample representative of at least 10% of patients anesthetized for surgical and radiological procedures. The independent variables (risk factors) collected included age, American Society of Anesthesiology (ASA) physical status, obesity, preexisting airway or lung disease, preexisting neuromuscular disease or hypotonia, morbid obesity, intraoperative bronchospasm and intraoperative laryngospasm. The primary outcome variables collected were Apnea or hypopnea, Laryngospasm, Bronchospasm, and prolonged Oxygen requirement. Apnea or hypopnea was defined by the need for bag mask ventilation, Laryngospasm by the requirement of a positive pressure ventilation of > 20 cmH2O or administration of succinylcholine, Bronchospasm by use of albuterol, and Oxygen requirement by continued oxygen administration to maintain SpO2>92% for 2 hours postoperatively.