Miniaturisation of cardiopulmonary bypass is an advanced perfusion technique need to be gain in use during cardiac surgery to minimize adverse effects of extracorporeal circulation. ie systemic inflammatory response syndrome, haemodilution. this presentation will give you a brief idea about miniaturized CPB circuit

1. Minimising cardiopulmonary
bypass in children
-Dinesh Patil

2. Abstract
• Challenges & advantage of minimising volume
• Contemporary circuit designs
• Clinical impact- Blood usage,SIRS, Neurological
outcomes

3. Challenges of cardiopulmonary bypass
the congenital patient
• Patient size
• Size mismatch between CPB circuit and
patient

4. Complexities of circulation, shunts &
collateral flow
• Presence of Aorto-Pulmonary collaterals

5. • Bardley et.al. reported pulmonary collateral flow
measured 49% of total bypass in group of patient
undergoing Fontan completion (2011)
• If this diverted flow couldn’t compensate, it can
lead to systemic malperfusion, anaerobic
metabolism, end organ injury, dysfunction
• Fuji.et.al (2009) evaluated 23 patients with
chronic cynotic condition undergoing CPB using
high flow bypass compared with standard flow
results in lower lactate level during bypass, higher
UO, reduction in Post-op effusions

6. Complexity of repair
• Air-blood interface due to intracardiac
venting, which can cause cellular injury and
inflammatory reaction

7. Cannulation & access to circulation
• Use of DHCA in the repair where direct aortic
& femoral cannulation is not possible

8. Potential goals of mini CPB
• To reduce Post CPB inflammatory response
• CPB in children associated with post-op
systemic inflammatory response
• Increase in proinflammatory cytokine release
• Increase in total body water
• End organ dysfunction

9. Mini CPB
• Reduces inflammatory response
• Decrease artificial surface area exposure &
contact activation
• Reducing priming volume & transfusion
requirement
• Preservation of HCT
• Reduced Post-op IL-6 superior
haemodynamics with lower PAP, PVR, and
increase in right ventricular cardiac index

10. • Howels-gurich & coworkers (2002) studies 63
patients with d-TGA undergoing arterial switch
operation and found IL-6, IL-8 post-op peaking
at 4hr correlating with CPB duration

12. Reduction in haemodilution & blood
transfusion requirement
• Requirement of blood tranfusion because of
desparity between patient blood volume &
CPB prime volume
• Risk of transfusion
• MOF following surgery
• Sepsis
• Red cell aggregation

13. • Many centre choose to prime the blood <3days &
filter before bypass
• Other reasons to avoid transfusion include risk of
transmissible viral infective risk, religious belief.
• When comparing fresh blood with blood stored
>12 days associated with higher lactate level
during CPB, but by the end of CPB this effect had
largely equalised ( schorder, Hanson 2005)

15. Target hematocrit during CPB
• In paediatric perfusion jonas & coworkers
(2003) studies 143 neonate & infant
undergoing two ventricle corrective surgery
and randomised to low HCT (21.5%) & high
HCT (27.8%) strategy during CPB
• The low HCT was associated with reduced
cardiac index in post-op phase & reduced
neurologoical outcomes in one year
evaluation

17. Mini CPB circuit design options in
congenital heart surgery
• MUF circuit simplification
• Some studies are failed to demonstrate a
major advantage of MUF over CUF on-bypass
filtration(thompson 2001)
• Requires additional circuit & prime volume
• Decrease total body water content, decrease
cytokine level, improve ventricular function,
decrease post-op ventilator requirement

18. • Use of integral arterial filter within oxygenator

19. Oxygenator selection
• Priming volume of oxygenator need to
consider
• Flow rate
• Easy of set-up
• cost

21. Reduction in pump tubing length
• Reduction in total length & cross-sectional
area of cpb tubing reduces prime volume, red
cell requirement & surface area exposure
• Use of remote pump head & moving entire
console closer to patient also significantly
reduce the tubing length
• Drawback
• Compromise with sterility

23. • Remote pump head used for arterial flow,
hemofilter, suction & vents. Allow all four lines
to be bought close to venous reservoir &
oxygenator
• Ando & coworkers (2004) for patient weighing
5kg or less. In this circuit remote pump head
were placed closed to operative field. Tubing
calibre was downsize to 5/32 inch except
pump head ¼ inch

24. • Total 158 patients of mean weight 4.3 kg
underwent CPB with this configuration. The
prime vol of circuit was 181ml and 116
patients (73%) underwent bypass without
blood prime with low HCT during CPB.
Minimum HCT during CPB was 15.2%
• Clinical outcomes-
• Operative mortality in one patient with
pulmonary hypertensive crises

25. • Despite low HCT no neurological event
encounter acutely or on later gross
assessment of psychomotor function by
questionarrie

26. Vacuum assisted venous drainage
• Application of vacuum to hard shell venous
reservoir
• Augmentation of venous flow by 44% with
pressure -50mmHg
• Pressure > -100 mmHg, trobleshooting of
venous cannula, collapse of SVC, IVC, and right
heart
• Unprimed venous line to decrease the prime
volume further (Darling 1998)

27. • Risk
• Aspirating air into arterial side without filled
venous reservoir and venous line. For these
reason its consider safer to prime venous line
• A clinical study in childen 5-20 kg on use of VAVD
associated with reduced prime vol & blood
transfusion requirement( need for blood 53%
compared with 33% using VAVD & vol of blood
transfused(Naknishi2001)

28. Clinical trials
• Kotani & coworkers(2007) achieved reduction
in prime vol by downsizing venous & arterial
tubing, utilising smaller prime
oxygenator(Dideco901) prime reduction from
575 to 323ml
• Results
• Reduced homologous blood usage
• HCT & other perfusion parameters & flow
remain similar in these groups

29. • Charity & coworkers (2007) compared blood
usage in neonate/ infants undergoing cpb with
circuit miniaturisation. Initial priming vol
(350ml) decreased to 172ml by downsizing
arterial & venous tubing.
• Using small prime oxygenator & removing
inlet arterial filter

30. • Results
• Decrease exogenous blood requirement
during bypass
• Reduced bleeding
• Higher post-op HCT
• Reduced ventilation time

31. Conclusion
• Miniaturisation is an area of active research in
congenital heart surgery
• Reduction in post-op inflammatory response
& preserves end organ function
• Improves patient outcome in acute phase
• Mini-CPB requires careful evaluation as new
circuit & technologies introduced in perfusion

32. Future…
• Debate continues- optimal perfusion- future
investigation require to assess the “critical
HCT” & other perfusion parameters
• Follow-up studies are needed- does
transfusion results in better long term
outcomes
• We should advocate for the freshest blood
• We should change ourselves

33. 1. Mini-bypass circuitry/ reduce transfusion
• Encourage technology, devolopment &
innovation
• And finally…work as a TEAM!

34. Thank you..