Abstract
Delirium is a common complication after cardiac surgery. The aim of our study was to determine the impact of hyperoxia episodes occurring during cardiopulmonary bypass (CBP) on the rate of delirium episodes in the postoperative period. 93 patients, aged ≥ 65, who underwent elective cardiac surgery (CBP <90 minutes) were enrolled. The occurrence of delirium episodes was examined every 12 hours for three days after surgery. Eleven patients (11.8%) developed postoperative delirium (POD (+)) and 83 did not (POD (-)). More incidences of severe hyperoxia (PaO2 ≥ 26.6kPa) during CBP were observed in the POD (+) group: 64% had ≥ 2 episodes of hyperoxia, 27% ≥ 3, and 18% ≥ 4, while in the POD (-) group: 42%, 13% and 1%, respectively (P=0.02). Patients in the POD (+) group had a higher maximum PaO2 during CBP than the POD (-) group (37 ± 5.8 vs 31.6 ± 6.6 kPa; P=0.01) and a higher mean PaO2 (30.1 ± 4.5 vs 26.1 ± 5.6 kPa; P=0.01). The optimal maximum PaO2 cut-off point for the occurrence of delirium was 33.2 kPa (AUC 0.72, P=0.001, sensitivity 75%, specificity 38%). We conclude that CBP hyperoxia episodes may be a risk factor associated with the occurrence of postoperative delirium.
Highlights
Delirium is one of the most common complications after cardiac surgery
We conclude that cardiopulmonary bypass (CBP) hyperoxia episodes may be a risk factor associated with the occurrence of postoperative delirium
Out of 93 patients included in the study, 11 (11.8%) developed postoperative delirium (group POD (+)) and 82 did not (group POD (-))
Summary
Delirium is one of the most common complications after cardiac surgery. The presence of delirium after cardiac surgery is associated with a higher mortality rate, increased length of Intensive Unit (ICU) stay [2], higher hospitalization costs [3] and a risk of readmission [4]. The occurrence of delirium during the postoperative period correlates with the development of long-term consequences after surgery such as cognitive decline and functional impairment, which in turn results in the deterioration of the patient’s quality of life [5]. Several pathophysiological mechanisms that contribute to the development of postoperative delirium have been presented, such as inflammation, disturbances in cerebral autoregulation, aortic plaque disruption, microemboli, Alzheimer-like cerebral pathology, and the neurotoxicity of anesthetics [7]
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