Vacuum-Assisted Venous Drainage (VAVD) is an augmented approach to drawing blood from the patient into the Heart-Lung Machine and one of the hundreds of unique devices and techniques that formulate cardiac surgery. The Heart-Lung Machine (the “pump”) functions as a cardiopulmonary bypass (CPB). By removing blood from the heart, re-oxygenating it, and pumping it back through the body, the CPB mechanically provides the essential functions that allow surgeons to work in a still environment while maintaining a specific chemical balance of drugs and blood components. Overall, the pump machinery may appear robust and daunting but is, in fact, intricate with very delicate resources and narrow margins of error.
Since the mid-1990s, VAVD has overtaken traditional gravity siphoning as a standard practice with CPB to allow for more technologically advanced and safe minimally invasive surgical techniques. However, this innovation does not come without its faults. The closed-circuit vacuum-assist method of venous drainage adds a higher degree of risk than that of the open siphon design. The VAVD Controller pulls blood from the heart (called venous return) into the cardiotomy reservoir by applying a low suction level. Perfusionists, the clinicians who operate this pump, must prevent damage to the blood during its journey outside the body. To avoid tiny air bubbles that can cause air embolisms and strokes in patients, called micro-gas emboli (MGEs), the American Academy of Blood Banking standards show that the vacuum should be limited to -60 mmHg. Any positive pressure would slow or decrease venous return, sending air back into the patient’s vessels, resulting in these MGEs.
The Boehringer Laboratories VAVD Controller (model 3931) is a Suction Regulator indicated explicitly for use with cardiopulmonary bypass. The Model 3931 device is constructed of aircraft-grade aluminum with a hydrophobic surface. It can efficiently vent and precisely regulate the amount of vacuum applied within the clinically acceptable range. The reservoir’s positive or excess negative pressurization is not to be feared. The device has a dedicated vapor trap, connection tubing, and a redundant factory set safety relief. Simplifying and standardizing the application of vacuum with this reliable device allows perfusionists and surgeons the peace of mind to utilize the most innovative minimally invasive surgical techniques in a bloodless surgical field.
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