Purpose of review: This is the first part of an eight paper review series on postoperative problems. This section will focus on common postoperative complications with an emphasis on definitions and epidemiology. The major topics covered are cardiovascular and respiratory complications. Other sections will highlight central nervous system and renal complications, postoperative nausea and vomiting, hypothermia, injuries and perioperative mortality. More details on specific problems will be covered later in the series.
Recent findings: The review will highlight recent aims to standardize definitions of postoperative morbidity.
Summary: Standardization of definitions is essential to enable high-quality multicenter, multinational research to be carried out. This is vital as we continue to focus on improving patient outcomes.