Systemic venous drainage: can we help Newton?☆

Abstract

In recent years substantial progress occurred in the techniques of cardiopulmonary bypass, but the factor potentially limiting the flexibility of cardiopulmonary bypass remains the drainage of the systemic venous return. In the daily clinical practice of cardiac surgery, the amount of systemic venous return on cardiopulmonary bypass is directly correlated with the amount of the pump flow. As a consequence, the pump flow is limited by the amount of venous return that the pump is receiving. On cardiopulmonary bypass the amount of venous drainage depends upon the central venous pressure, the height differential between patient and inlet of the venous line into the venous reservoir, and the resistance in the venous cannula(s) and circuit. The factors determining the venous return to be taken into consideration in cardiac surgery are the following: (a) characteristics of the individual patient; (b) type of planned surgical procedure; (c) type of venous cannula(s); (d) type of circuit for cardiopulmonary bypass; (e) strategy of cardiopulmonary bypass; (f) use of accessory mechanical systems to increased the systemic venous return. The careful pre-operative evaluation of all the elements affecting the systemic venous drainage, including the characteristics of the individual patient and the type of required surgical procedure, the choice of the best strategy of cardiopulmonary bypass, and the use of the most advanced materials and tools, can provide a systemic venous drainage substantially better than what it would be allowed by the simple "Law of universal gravitation" by Isaac Newton.

Impact of Vacuum-Assisted Venous Drainage on Forward Flow in Simulated Pediatric Cardiopulmonary Bypass Circuits Utilizing a Centrifugal Arterial Pump Head

“…Traditional gravity siphon drainage with small size cannulae and tubings may provide insufficient blood return to the cardiotomy reservoir and compromise effective forward flow and tissue perfusion [1,2] . Assisted venous drainage techniques such as kinetic-assisted venous drainage (KAVD) and vacuum-assisted venous drainage (VAVD) are used to improve venous return [3] .…”

Prevention of Caval Collapse During Venous Drainage for CPB

“…[5][6][7][8][9][10][11] There are numerous factors that can influence the quality of venous drainage during CPB including venous cannula design and venous cannula positioning. 4 Improved flow of blood drainage can be achieved if better cannula designs are used as we have previously demonstrated for the Smartcanula (Smartcanula LLC, Lausanne, Switzerland), which is based on the "collapsed insertion and expansion in situ" principle. 2,12,13 With its self-expanding design, this device acts also as a spacer preventing the vein from collapsing, and therefore allows all collateral blood to be drained directly towards the pump oxygenator.…”

“…[1][2][3][4] The amount of venous blood drained from the patient determines the flow rate that can be achieved during cardiopulmonary bypass (CPB), and end organ perfusion. Venous drainage defines also the amount of blood that stays in the patient's cardiovascular system during CPB.…”

Perfusionist strategies for blood conservation in pediatric cardiac surgery

“…An increase in gaseous microemboli is a complica-tion related to vacuum-assisted venous drainage. However, this drawback is avoidable by adhering to specifc parameters [24,25] . If the maximal value of the vacuum remains under -40 mmHg, the level of embolic activity is equivalent to that seen during gravity-siphon venous drainage [26] .…”