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Is kidney function altered by the duration of cardiopulmonary bypass?
Joachim Boldt1, Torsten Brenner, Andreas Lehmann
1Department of Anesthesiology and Intensive Care Medicine, Klinikum der Stadt Ludwigshafen, Ludwigshafen, Germany. boldtj@gmx.net
Insights
Prolonged cardiopulmonary bypass (CPB) significantly increases kidney damage markers. Shorter CPB times (<70 minutes) result in less kidney injury compared to longer durations (>90 minutes).
Area of Science:
- Nephrology
- Cardiology
- Surgical Research
Background:
- Cardiopulmonary bypass (CPB) is frequently associated with acute kidney injury.
- Sensitive biomarkers are crucial for detecting early kidney damage during and after cardiac surgery.
Purpose of the Study:
- To investigate the impact of cardiopulmonary bypass duration on kidney function.
- To assess kidney damage using sensitive urinary biomarkers in relation to CPB time.
Main Methods:
- A prospective study comparing 50 patients with CPB < 70 minutes to 50 patients with CPB > 90 minutes.
- Measurement of creatinine clearance, fractional excretion of sodium, and urinary kidney-specific proteins (N-acetyl-beta-D-glucosaminidase, alpha1-microglobulin, glutathione transferase-pi, and glutathione transferase-alpha).
- Biomarker analysis was performed pre-operatively, post-operatively, and on days 1 and 2 post-ICU admission.
Main Results:
- All measured kidney-specific proteins significantly increased post-CPB in both groups.
- Patients with CPB > 90 minutes exhibited significantly higher elevations in kidney-specific proteins compared to those with CPB < 70 minutes.
- Urinary biomarkers returned to baseline levels by postoperative day 2 in the shorter CPB group, but remained elevated in the longer CPB group.
Conclusions:
- CPB duration exceeding 90 minutes is associated with more pronounced kidney damage than CPB under 70 minutes, as indicated by sensitive urinary proteins.
- Further research is needed to determine if renal protection strategies benefit patients with pre-existing renal dysfunction undergoing prolonged CPB.
Background:
Cardiopulmonary bypass (CPB) is considered responsible for kidney damage. By using sensitive markers of kidney damage we assessed whether the length of CPB influences kidney function.
Methods:
In a prospective study, 50 consecutive cardiac operation patients with CPB times of less than 70 minutes were compared with 50 consecutive patients showing CPB times of more than 90 minutes. Aside from creatinine clearance and fractional excretion of sodium, urine concentrations of N-acetyl-beta-D-glucosaminidase, alpha1-microglobulin, glutathione transferase-pi, and glutathione transferase-alpha were measured after induction of anesthesia at the end of the operation, and on the first and second postoperative days in the intensive care unit.
Results:
CPB times were 58 +/- 12 minutes and 116 +/- 18 minutes, respectively. Hemodynamics, volume replacement, and use of catecholamines during cardiopulmonary bypass (CPB) were without significant differences between groups. Concentrations of all kidney-specific proteins increased significantly after CPB, showing the highest significant increases in the CPB more than 90 minutes group (eg, glutathione transferase-alpha CPB > 90 minutes from 3.0 +/- 1.0 to 12.9 +/- 2.9 microg/L; glutathione transferase-alpha CPB < 70 minutes from 2.4 +/- 0.5 to 5.5 +/- 1.2 microg/L). By the second postoperative day, urine concentrations of kidney-specific proteins had returned to almost baseline in the CPB less than 70 minutes patients, but remained slightly elevated in the other group.
Conclusions:
Patients with CPB times more than 90 minutes showed more pronounced kidney damage than patients with CPB times less than 70 minutes as assessed by sensitive kidney-specific proteins. Whether patients with preexisting renal dysfunction undergoing prolonged CPB times would profit from renal protection strategies needs to be elucidated.