ASSISTED VENOUS DRAINAGE

Gravity DrainageGravity 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

Why Assisted Venous Drainage?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)

Assisted Venous Return Techniques:Assisted Venous Return Techniques:

• Roller- Pump Assisted

– “Better-Header”

• Kinetic-Assisted

• Vacuum-Assisted

Kinetic-Assisted Venous Kinetic-Assisted Venous DrainageDrainage

• Involves the integration of a centrifugal pump into the venous line to actively aspirate venous blood from the patient

Roller Pump Assisted Venous Roller Pump Assisted Venous DrainageDrainage

• Involves the integration of a roller pump into the venous line to actively aspirate venous blood from the patient

Vacuum-Assisted Venous Vacuum-Assisted Venous DrainageDrainage

• 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.

Vacuum-Assisted Venous Vacuum-Assisted Venous DrainageDrainage

Advantages of VAVDAdvantages 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 ]

Disadvantages and PitfallsDisadvantages 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

Advantages of VAVD over other Advantages of VAVD over other AVD TechniquesAVD Techniques

• Superior handling of Venous Line Air

• Easy to set-up

• Cheaper

EquipmentEquipment

• 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

Special ConsiderationsSpecial 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.

Special ConsiderationsSpecial 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.