Through a series of sequential analyses, retrospective database exploration looking for linkages and associations between the use of processed electroencephalogram (EEG) and/or cerebral saturation monitoring and patient outcomes post-cardiothoracic surgery will be explored.

The purpose of this study is to mine the Premier Healthcare Database to:

1. define the incidence of post-operative cognitive complications, acute kidney injury and stroke after specific cardiac surgical procedures (defined as: coronary artery bypass graft [CABG], Aortic Valve Replacement, Mitral valve repair, Mitral valve replacement, thoracic aortic operation, combined CABG and Valve replacement or repair ; and
2. Determine the incremental increase in the length of hospitalization and cost of hospitalization among cardiac surgical patients who suffer postoperative cognitive complications, acute kidney injury and stroke; and
3. Determine the effectiveness of intraoperative neuromonitoring with cerebral saturation and/or processed electroencephalogram (EEG) monitoring on the incidence of post-operative cognitive complications, acute kidney injury and stroke as a consequence of specific cardiac surgery procedures.

The Premier Healthcare Database is a privately owned database that represents approximately 1/5th of all United States hospitalizations annually. It includes all International Classification of Diseases-9th Revision (ICD-9) and International Classification of Diseases-Clinical Modification (ICD-9-CM) diagnosis and procedure codes recorded by the hospital, as well as a limited set of Current Procedural Terminology (CPT)-4 codes. Within the database, discharge-level data include information on patient and provider characteristics, diagnoses and procedures, hospital resource utilization, and charges/cost data for all entries, including pharmacy charges.

Inclusion Criteria:

• All adult (age >=18 years) hospitalized patients who underwent major cardiac surgical procedure requiring cardiopulmonary bypass captured in the premier database from January 1, 2010 - December 31, 2014 (5 year period)

Exclusion Criteria:

• <18 years of age
• Cardiac procedures not requiring cardiopulmonary bypass

All adult (age >=18 years) inpatients who underwent major cardiac surgical procedure requiring cardiopulmonary bypass captured in the Premier database from January 1, 2010 - December 31, 2014 (5 year period).

There is no individual participant data in this retrospective database study.