title: How to prevent venous cannula orifice obstruction during extracorporeal circulation.
abstract: Venous cannula orifice obstruction is an underestimated problem during augmented cardiopulmonary bypass (CPB), which can potentially be reduced with redesigned, virtually wall-less cannula designs versus traditional percutaneous control venous cannulas. A bench model, allowing for simulation of the vena cava with various affluent orifices, venous collapse and a worst case scenario with regard to cannula position, was developed. Flow (Q) was measured sequentially for right atrial+hepatic+renal+iliac drainage scenarios, using a centrifugal pump and an experimental bench set-up (afterload 60 mmHg). At 1500, 2000 and 2500 RPM and atrial position, the Q values were 3.4, 6.03 and 8.01 versus 0.77*, 0.43* and 0.58* l/min: p<0.05* for wall-less and the Biomedicus® cannula, respectively. The corresponding pressure values were -15.18, -31.62 and -74.53 versus -46.0*, -119.94* and -228.13* mmHg. At the hepatic position, the Q values were 3.34, 6.67 and 9.26 versus 2.3*, 0.42* and 0.18* l/min; and the pressure values were -10.32, -20.25 and -42.83 versus -23.35*, -119.09* and -239.38* mmHg. At the renal position, the Q values were 3.43, 6.56 and 8.64 versus 2.48*, 0.41* and 0.22* l/min and the pressure values were -9.64, -20.98 and -63.41 versus -20.87 -127.68* and -239* mmHg, respectively. At the iliac position, the Q values were 3.43, 6.01 and 9.25 versus 1.62*, 0.55* and 0.58* l/min; the pressure values were -9.36, -33.57 and -44.18 versus -30.6*, -120.27* and -228* mmHg, respectivly. Our experimental evaluation demonstrates that the redesigned, virtually wall-less cannulas, allowing for direct venous drainage at practically all intra-venous orifices, outperform the commercially available control cannula, with superior flow at reduced suction levels for all scenarios tested.
authors.affiliation: Cardiovascular Research, Department of Cardio-Vascular Surgery, University Hospital-CHUV, Lausanne, Switzerland saad.abdel-sayed@chuv.ch.
authors.forename: S
authors.initials: S
authors.lastname: Abdel-Sayed
authors.affiliation: Laboratory of Movement Analysis and Measurement, Ecole Polytechnique Fédéral de Lausanne, Lausanne, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Favre
authors.affiliation: Cardiovascular Research, Department of Cardio-Vascular Surgery, University Hospital-CHUV, Lausanne, Switzerland.
authors.forename: L K
authors.initials: LK
authors.lastname: von Segesser
mesh_terms: D061807:Catheter Obstruction; D005112:Extracorporeal Circulation / Q000295:instrumentation / Q000379:methods; D006801:Humans; D011312:Pressure; D062666:Vascular Access Devices; D014684:Venae Cavae
keywords: augmentation; cannulation; cardiopulmonary bypass; extracorporeal circulation; flow rate; negative pressure; venous drainage