Air Removal Characteristics of Integrated AF

By: Marco C. Stehouwer, Chris Boers, Roel de Vroege, Johannes C. Kelder, Alaaddin Yilmaz, Peter Bruins

The use of minimized extracorporeal circuits (MECC) in cardiac surgery is an important measure to increase the biocompatibility of cardiopulmonary bypass during coronary artery bypass grafting (CABG).
These circuits eliminate volume storage reservoirs and bubble traps to minimize the circuit. However,
the reduction in volume may increase the risk of gaseous microemboli (GME). The MECC system as
used by our group consists of a venous bubble trap, centrifugal pump, and an oxygenator. To further
reduce the risk of introducing GME, an oxygenator with an integrated arterial filter was developed
based on the concept of minimal volume and foreign surface. We studied the air removal characteristics of this oxygenator with and without integrated arterial filter. The quantity and volume of GME were
measured with precision at both the inlet and outlet of the devices.
Our results showed that integration of an arterial filter into this oxygenator increased GME reducing
capacity from 69.2% to 92%. Moreover, we were able to obtain data on the impact of an arterial filter
on the exact size-distribution of GME entering the arterial line.
The present study demonstrates that an MECC system and oxygenator with integrated arterial filter
significantly reduces the volume and size of GME. The use of an integrated arterial filter in an MECC system may protect the patient from the deleterious effects of CPB and may further improve patient safety.

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Rational Approach to Perioperative Fluid Management

By: Daniel Chappell, M.D.,* Matthias Jacob, M.D.,* Klaus Hofmann-Kiefer, M.D.,* Peter Conzen, M.D.,† Markus Rehm, M.D.

Replacement of assumed preoperative deficits, in addition to generous substitution of an unsubstantiated increased insensible perspiration and third space loss, plays an important role in current perioperative fluid regimens. The consequence is a positive fluid balance and weight gain of up to 10 kg, which may be related to severe complications. Because the intravascular blood volume remains unchanged and insensible perspiration is negligible, the fluid must accumulate inside the body. This concept brings into question common liberal infusion regimens. Blood volume after fasting is normal, and a fluid-consuming third space has never been reliably shown. Crystalloids physiologically load the interstitial space, whereas colloidal volume loading deteriorates a vital part of the vascular barrier. The endothelial glycocalyx plays a key role and is destroyed not only by ischemia and surgery, but also by acute hypervolemia. Therefore, undifferentiated fluid handling may increase the shift toward the interstitial space. Using the right kind of fluid in appropriate amounts at the right time might improve patient outcome.

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