Abstract
BackgroundDelirium occurs frequently following cardiothoracic surgery, and infectious disease is an important risk factor for delirium. Surgery and cardiopulmonary bypass induce suppression of the immune response known as immunoparalysis. We aimed to investigate whether delirious patients had more pronounced immunoparalysis following cardiothoracic surgery than patients without delirium, to explain this delirium-infection association.MethodsA prospective matched case–control study was performed in two university hospitals. Cytokine production (tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-8 and IL-10) of ex vivo lipopolysaccharide (LPS)-stimulated whole blood was analyzed in on-pump cardiothoracic surgery patients preoperatively, and at 5 timepoints up to 3 days after cardiothoracic surgery. Delirium was assessed by trained staff using two validated delirium scales and chart review.ResultsA total of 89 patients were screened of whom 14 delirious and 52 non-delirious patients were included. Ex vivo-stimulated production of TNF-α, IL-6, IL-8, and IL-10 was severely suppressed following cardiothoracic surgery compared to pre-surgery. Postoperative release of cytokines in non-delirious patients was attenuated by 84% [IQR: 13–93] for TNF-α, 95% [IQR: 78–98] for IL-6, and 69% [IQR: 55–81] for IL-10. The attenuation in ex vivo-stimulated production of these cytokines was not significantly different in patients with delirium compared to non-delirious patients (p > 0.10 for all cytokines).ConclusionsThe post-operative attenuation of ex vivo-stimulated production of pro- and anti-inflammatory cytokines was comparable between patients that developed delirium and those who remained delirium-free after on-pump cardiothoracic surgery. This finding suggests that immunoparalysis is not more common in cardiothoracic surgery patients with delirium compared to those without.
Highlights
Delirium, characterized by an acute onset of inattention and other cognitive deficits, is a common postoperative complication in cardiothoracic surgery patients with an incidence of 10–20% [1]
Previous studies showed that various pro- and antiinflammatory mediators may be associated with delirium [4,5,6], and these may account for the development of immunoparalysis [7,8,9]
Given the association between severe inflammation and the development of both delirium and immunoparalysis, we aimed to test the hypothesis that cardiac surgery-induced immunoparalysis is more pronounced in patients that develop delirium compared to those who do not
Summary
Delirium, characterized by an acute onset of inattention and other cognitive deficits, is a common postoperative complication in cardiothoracic surgery patients with an incidence of 10–20% [1]. Previous studies showed that various pro- and antiinflammatory mediators may be associated with delirium [4,5,6], and these may account for the development of immunoparalysis [7,8,9] This suppression of the immune response has been shown in other states to be associated with severe systemic inflammation, e.g. sepsis, and is associated with an increased susceptibility to secondary infections and morbidity [10]. Patients with delirium appear to be prone to develop a secondary infection, and an infectious disease is a risk factor for delirium [3]. Delirium occurs frequently following cardiothoracic surgery, and infectious disease is an important risk factor for delirium. We aimed to investigate whether delirious patients had more pronounced immunoparalysis following cardiothoracic surgery than patients without delirium, to explain this delirium-infection association
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