title: Effect of Vacuum on Venous Drainage: an Experimental Evaluation on Pediatric Venous Cannulas and Tubing Systems.
abstract: BACKGROUND
  To observe how vacuum assisted venous drainage (VAVD) may influence the flow in a cardiopulmonary bypass circuit with different size of venous lines and cannulas.
  
  
  METHODS
  The experimental circuit was assembled to represent the cardiopulmonary bypass circuit routinely used during cardiac surgery. Wall suction was applied directly, modulated and measured into the venous reservoir. The blood flow was measured with a flow-meter positioned on the venous line. The circuit prime volume was replaced with group O date expired re-suspended red cells and Plasmalyte 148 to a hematocrit of 28% to 30%.
  
  
  RESULTS
  In an open circuit with gravity siphon venous drain, angled cannulae drain more than straight ones regardless the amount of suction applied to the venous line (16 Fr straight cannula (S) drains 90 ml/min less than a 16 Fr angled (A) with a siphon gravity). The same flow can be obtained with lower cannula size and higher suction (i.e. 12 A with and -30 mmHg). Tables have been created to list how the flow varies according to the size of the cannulas, the size of the venous tubes, and the amount of suction applied to the system.
  
  
  CONCLUSIONS
  Vacuum assisted venous drainage allows the use of smaller cannulae and venous lines to maintain a good venous return, which is very useful during minimally invasive approaches. The present study should be considered as a preliminary attempt to create a scientific-based starting point for a uniform the use of VAVD.
authors.affiliation: Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Surgery, University of Padua, Italy.
authors.forename: V L
authors.initials: VL
authors.lastname: Vida
authors.affiliation: Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Surgery, University of Padua, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Bhattarai
authors.affiliation: Pediatric and Congenital Cardiac Surgery Unit, Department of Cardiac, Thoracic and Vascular Surgery, University of Padua, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Speggiorin
authors.affiliation: Cardiothoracic Surgery Department, The Great Ormond Street Hospital for Children NHS Trust, London, UK.
authors.forename: F
authors.initials: F
authors.lastname: Zanella
authors.affiliation: Cardiac Perfusion Unit, University of Padua, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Stellin
mesh_terms: D002315:Cardiopulmonary Bypass / Q000295:instrumentation*; D002405:Catheterization, Central Venous / Q000295:instrumentation*; D002648:Child; D004322:Drainage; D004867:Equipment Design; D006801:Humans; D066298:In Vitro Techniques; D008955:Models, Cardiovascular; D015203:Reproducibility of Results; D014618:Vacuum; D014680:Veins; D014690:Venous Pressure
keywords: cardio-pulmonary bypass; experimental study; vacuum assisted drainage.