These include vascular surgeries (supra or infra-inguinal), intraperitoneal surgeries, intra-thoracic surgeries, head and neck surgeries, spine surgeries, urologic surgeries, and proximal extremity orthopedic surgeries. Peripheral extremity surgeries (wrist or below, and ankle or below), in addition to appendectomies and cholecystectomy surgeries will be excluded from this study.