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Serum creatinine patterns in coronary bypass surgery patients with and without postoperative cognitive dysfunction
Madhav Swaminathan1, Brian J McCreath, Barbara G Phillips-Bute
1Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA.
Insights
Postoperative cognitive dysfunction after coronary artery bypass graft (CABG) surgery is not linked to significant renal injury. Unlike stroke complications, cognitive deficits do not increase the risk of acute kidney injury following CABG.
Area of Science:
- Cardiology
- Nephrology
- Neuroscience
Background:
- Renal dysfunction is a known complication following coronary artery bypass graft (CABG) surgery.
- Previous studies indicated a higher risk of renal injury in CABG patients who experienced stroke.
- The relationship between cognitive dysfunction and renal injury post-CABG was not previously established.
Purpose of the Study:
- To investigate the association between postoperative cognitive dysfunction and acute perioperative renal injury in patients undergoing CABG surgery.
- To determine if cognitive deficits after CABG are linked to changes in serum creatinine levels.
Main Methods:
- Prospective data collection from 282 patients undergoing elective CABG.
- Baseline and 6-week postoperative psychometric testing to assess cognitive function.
- Analysis of peak serum creatinine changes in relation to cognitive deficit (CD) and cognitive index.
Main Results:
- Forty percent of patients exhibited cognitive deficit (CD) at 6 weeks post-CABG.
- No significant association was found between peak postoperative creatinine changes and either CD or cognitive index.
- The data suggest cognitive dysfunction is not linked to major increases in postoperative renal dysfunction.
Conclusions:
- Postoperative cognitive dysfunction after CABG is not associated with significant acute renal injury.
- Unlike stroke, cognitive deficits do not appear to increase the risk of renal dysfunction following cardiac surgery.
- Factors contributing to subtle cognitive dysfunction post-CABG do not seem to have clinically relevant renal implications.
Unlabelled:
Renal dysfunction is common after coronary artery bypass graft (CABG) surgery. We have previously shown that CABG procedures complicated by stroke have a threefold greater peak serum creatinine level relative to uncomplicated surgery. However, postoperative creatinine patterns for procedures complicated by cognitive dysfunction are unknown. Therefore, we tested the hypothesis that postoperative cognitive dysfunction is associated with acute perioperative renal injury after CABG surgery. Data were prospectively gathered for 282 elective CABG surgery patients. Psychometric tests were performed at baseline and 6 wk after surgery. Cognitive dysfunction was defined both as a dichotomous variable (cognitive deficit [CD]) and as a continuous variable (cognitive index). Forty percent of patients had CD at 6 wk. However, the association between peak percentage change in postoperative creatinine and CD (parameter estimate = -0.41; P = 0.91) or cognitive index (parameter estimate = -1.29; P = 0.46) was not significant. These data indicate that postcardiac surgery cognitive dysfunction, unlike stroke, is not associated with major increases in postoperative renal dysfunction.
Implications:
We previously noted that patients with postcardiac surgery stroke also have greater acute renal injury than unaffected patients. However, in the same setting, we found no difference in renal injury between patients with and without cognitive dysfunction. Factors responsible for subtle postoperative cognitive dysfunction do not appear to be associated with clinically important renal effects.