Delirium Following Cardiac Surgery is Associated with Respiratory and Metabolic Alterations during Early Postoperative Course

Background: Postoperative delirium (POD) is a serious complication after cardiac surgery. Respiratory and metabolic alterations after cardiac surgery might impact the occurrence of POD. The aim of our analysis was to identify specific respiratory and metabolic parameters that indicate patients at risk for developing POD during early postoperative intensive care.

Methods: We performed the prospective observational FINDERI study in patients aged ≥50 years undergoing elective cardiac surgery. POD was identified using the Confusion Assessment Method for Intensive Care Units (CAM-ICU). All laboratory parameters were collected once a day throughout the patients’ ICU stay starting with the ICU admission after cardiac surgery (D0) and continuing for the next 4 days (D1-D4). We used a mixed model for repeated measurements (MMRM) to determine factors associated with the occurrence of POD. Finally, we calculated Cohen’s d to describe the effect sizes.

Results: We analyzed data from 475 patients (372 males; age 68.31 ± 8.29 years), of whom 102 (21%) developed POD. In the MMRM, we found the following associations between respiratory parameters and POD on the day of the ICU admission (D0): In patients presenting with POD versus patient without POD there was significantly higher arterial pCO2 (d = 0.401, p = 0.0003), lower arterial pH (d = −0.435; p < 0.0001), and higher arterial pO2 (d = 0.664; p < 0.0001) present. Furthermore, we found significantly lower hemoglobin (d = −0.387; p < 0.0001), hematocrit (d = −0.387; p < 0.0001), and higher blood glucose (d = 0.618; p < 0.0001) in POD patients vs. non-POD patients on D0. Finally, other metabolic parameters such as blood calcium (d = 0.383; p = 0.0003), chloride (d = 0.330; p = 0.0023), sodium (d = 0.338; p = 0.0010), lactate (d = 0.683; p < 0.0001), or serum urea (d = 0.200; p = 0.0445) were significantly higher in patients with POD at D1.

Conclusion: The results of this analysis indicate an association between the occurrence of POD and altered early postoperative laboratory parameters in patients undergoing cardiac surgery. Our data suggest that abnormal blood gas levels play an important role in the development of POD. Optimized ventilation parameters and metabolic compensation during ICU stay might be associated with reduced likelihood of POD after cardiac surgery.

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Artikel online veröffentlicht:
11. Februar 2025