Pathogenesis of gaseous microemboli in cardiac surgery. a comprehensive overview of deairing procedures, operative interactions and risk factors to mitigate postoperative cerebral disorders

In order to ensure both surgical safety and reliability, operative management of patients undergoing cardiac surgery requires stringent standards and awareness from cardiac surgeons, anesthesiologists and perfusionists. Among these standards, deairing cardiac chambers and reducing production of gaseous embolism, after open heart surgery, remain a crucial step and a major challenge to alleviate dire and life-threatening complications. Therefore, deairing maneuvers necessitate caution and methodology to reduce incidence of neurological complications and systemic side effects. In order to provide an overview of existing literature about, deairing procedures in cardiac surgery, factors involved in pathogenesis of gaseous microemboli, available options to improve brain monitoring and discuss whether new recommendations might still be relevant to improve neurological postoperative outcome in patients undergoing cardiac surgery, this narrative review encompassed specific and relevant searches in PubMed, Copernicus, Web of Science and Google Scholar databases. 55 and 72 studies were retrieved in the past 40 years with the focus of deairing procedures and pathogenesis of gaseous microemboli respectively. The multiple techniques reported to achieve appropriate deairing of cardiac chambers are well standardized and necessitate to be highlighted and regularly rehearsed since they demand awareness about potential cerebral and systemic deleterious complications related to air embolism. This review showed efficacy of dearing maneuvers as long as they follow strict and adequate guidelines and confirmed that a « zero-risk» is not a realistic option since use of CPB as well as patient comorbidity factors obviously influence occurence of air embolic side-effects. Finally, irrespective of efficient deairing procedures, understanding factors involved in pathogenesis of gaseous microemboli combined with a rigorous and rationale preoperative identification of patient-related risks to predict cerebral disorders are likely the key points of this major issue.