The relationship between neurocognitive decline and the heart‐lung machine

Surgery involving the use of cardiopulmonary bypass (CPB) has long been associated with cerebral changes and may also contribute to adverse neurocognitive outcomes. However, there is a debate as to whether bypass itself is responsible for these changes. We conducted a systematic literature review on PubMed, supplementing our work with recent articles from other sources to examine the current evidence on neurocognitive decline associated with CPB. While surgeries involving CPB appear to be associated with cerebral changes and potentially with neurocognitive decline, it is unclear as to whether decline is related to the procedure itself. It is possible that the impacts of CPB can be more readily observed among individuals with preoperative cognitive impairment. It is thus important to screen for subtle and more apparent preoperative cognitive impairment as a risk factor for adverse outcomes. Further research, comparing on-pump and off-pump cohorts and involving intensive screening of preoperative cognitive decline, is indicated to elucidate the true neurocognitive consequences of the heart-lung machine.