ASSISTED VENOUS DRAINAGE

1. ASSISTED VENOUS DRAINAGE

2. Gravity Drainage Patient to reservoir height gradient [ table height ] Venous line resistance as contributed by the venous cannulae ( cannulation site ) Central venous pressure Venous line length & size Venous reservoir

3. Why Assisted Venous Drainage? • Adults • Video-assisted surgical procedures and minimally invasive techniques with CPB • Higher support flows can be achieved with cannulae of smaller diameter • The primary aim of AVD is to optimize venous return flow with the utilization of a reduced diameter venous cannulae • Pediatrics • Reduce priming volume (VAVD) • To facilitate drainage with complex venous cannulation (air locks)

4. Assisted Venous Return Techniques: • Roller- Pump Assisted • “Better-Header” • Kinetic-Assisted • Vacuum-Assisted

5. Kinetic-Assisted Venous Drainage • Involves the integration of a centrifugal pump into the venous line to actively aspirate venous blood from the patient

6. Roller Pump Assisted Venous Drainage • Involves the integration of a roller pump into the venous line to actively aspirate venous blood from the patient

7. Vacuum-Assisted Venous Drainage • With this technique, the venous line is connected directly to a sealed hard shell venous reservoir • A regulated suction to the venous reservoir and closing all vented ports.

8. Vacuum-Assisted Venous Drainage

9. Advantages of VAVD • Improved venous return • Lowering the priming volume. • Markedly reduced intra-cardiac suction levels • Improved visibility and ability to use smaller incisions • Alternative venous cannulation sites • In some Re-Do cases, may eliminate need to dissect for snares around the Cava • Almost impossible to have an air-lock in the venous line • Improved drainage in special procedures. [ Heart port, modified access cases ]

10. Disadvantages and Pitfalls • Possibility of transmission of gaseous micro-emboli form the venous line to the arterial side of the circuit • Concerns on the effect of higher negative pressure on the RA and coronary sinus(due to Vacuum) • It may cause displacement of retrograde cardioplegia cannulae • It may distort the inter-atrial septum due to negative pressure in the RA • Over pressurization of the sealed venous reservoir • Increase arterial line filter shunt

11. Advantages of VAVD over other AVD Techniques • Superior handling of Venous Line Air • Easy to set-up • Cheaper

12. Equipment • CPB circuit with a sealed hard shell venous reservoir & integrated oxygenator • Pressure vacuum regulator with custom VAVD tubing set • Negative and positive pressure monitoring device • A very responsive positive pressure relief valve

18. Special Considerations • Care should be taken when adding fluids through the quick prime line • Care should be taken when administering pharmaceuticals through the manifold. • Watch the negative pressure when adjusting the vent and the inter-cardiac suction flow. • If venous return ceases during CPB, clamp the venous line for a second and release. • Preventative measures to prevent air being pulled in the circuit have to be taken.

19. Special Considerations • In the event of atrial tear or unsecured caval canulae, side clamping of the venous line is essential • VAVD is no substitution for good cannulation • If excessive venous chatter occurs, consider hypovolemia, cannula size and cannula position • If circulatory arrest is required, vacuum is removed from the reservoir and only applied again when restarting bypass • Always remember to vent the venous reservoir when down on flow or when VAVD is not in use.