The Effects of Fluid Accumulation on Cognition, Wound Healing, and Heart Rhythm/Rate in Patients Undergoing Aortocoronary Bypass Surgery

Objectives: Fluid accumulation due to SIRS is a major complication in patients undergoing cardiac surgery with CPB. Above a certain amount, fluid accumulation can cause organ or multiorgan dysfunction and in some extreme cases organ failure. In this research project, we studied the possible effects of fluid accumulation on cognition, wound healing, and heart rhythm and rate.

Methods: In this prospective clinical trial, we included 265 patients operated between 2017 and 2018. All patients underwent CABG with CPB. Data collection was performed manually and digitally through our PDMS (patient data management system). We used the CAM-ICU and four AT tests to assess the cognitive function of our patients. These tests were performed for 7 days after extubation and without psychiatric medication. A routine control of the wounds and ECG-registrations was carried out. We used the IBM SPSS statistics to perform the statistical analysis. Here we observed general fluid accumulation and also fluid accumulation per kg BW (body weight).

Results: The possible effects of fluid accumulation varied from mild cognitive malfunction to pronounced delirium. These were significant in patients accumulating above 5 L (> 0.059 L/kg BW) of fluid. The patients accumulating 0 to 3 (0.017 L/kg BW) L of fluid showed only 6% hyperactive delirium compared to the group accumulating 5 to 10 L (0.089 L/kg BW), who showed 33% hyperactive delirium. In the group, above 10 L (above 0.11 L/kg BW), a much higher incidence of cognitive dysfunction was seen. Persistent fluid discharge in oedema situation led to wound dehiscence and in some cases to wound infection. While wound infection was only seen in 1% of the group with 0 to 3 L, this incidence rises to 6.25% of the group with 5 to 10 L. No significant effects of fluid accumulation on heart rate were observed. However, we could see that patients with a fluid accumulation above 5 L showed more arrhythmia due to quick fluid loss induced through diuretics.

Conclusion: Patients undergoing cardiac surgery with CPB suffer from various degrees of fluid overload, which has been associated with increased mortality and morbidity. According to our findings, fluid accumulation of up to 3 L (0.017 L/kg BW) is well tolerated. However, an overload above 5 L (0.089 L/kg BW) appears to be associated with a much higher risk of delirium and wound infection. An optimal strategy to minimalize fluid overload is extremely important for these patients.