Impact of cardiopulmonary bypass on acute kidney injury following coronary artery bypass grafting: a matched pair analysis

Comparing 714 on pump and 714 off pump CABG patients, the investigators investigated the incidence of Acute Kidney Injury (AKI) and whether cardiopulmonary bypass time and or duration were independent contributors to AKI.  The investigators concluded that there are no differences in the incidence of AKI during  CABG surgery employing CPB. Use of off-pump bypass for patients with pre existing AKI may avoid further injury.

As the debate rages on about which technique is superior, several concerns come to mind.

1. When comparing on pump to off pump most studies do not look at the perfusion circuit as a whole to determine prime volume, which contributes to excessive hemodilution and is associated with AKI and increased transfusions.

2. Most studies do not evaluate the use of intra-aortic filtration for the capture of atheroma during aortic cross clamp application and removal. These potential embolic events are known contributors to renal, neurologic, and other sequelae.

3. Most studies do not include data such as continuous cardiac output measurements or cerebral oximetry measurements during off pump CABG. Cardiac anesthesiologists are excellent clinicians that can give the surgeon whatever systemic pressure is desired, while in reality, perfusion may be severely compromised.

4. During on pump surgery, would it be beneficial to perform continuous veno-veno hemofiltration with bicarb based solutions to clear pro inflammatory mediators and maintain physiologic homeostasis. This is more easily achieved in the on pump group and it perhaps a worthwhile addition to the CPB circuit to investigate in regards to reducing post op AKI.