Neonates and pediatric overview
Many pediatric organ systems are immature / vulnerable
Neonates have higher metabolic demands
Neonates have IMMATURE MYOCARDIUM (matures 3-12 months)
Neonates utilize GLUCOSE OXIDATION
Immature myocardium prone to “stretch injury”
Utilize alpha-stat and pH-stat blood gas management
adults overview
Adult circuits tend to be “one size fits all”
Many adult organ systems have acquired disease
Some organ systems have failed
Adults utilize FATTY ACID DEPENDENT energy source
Not affected as much by prime volume dilution
Mature clotting cascade and organ systems
Utilize mostly alpha-stat and some pH-stat blood gas management
estimating blood volumes: Weight (kg): <10 11-20 21-30 31-40 >40
Blood volume (cc/kg) < 10 = 85 11-20 = 80 21-30 = 75 31-40 = 70 > 40 = 65 - used for calculating post dilutional hematocrit
Circuits are commonly called: 3/16” x ¼” ¼” x ¼” ¼” x 3/8” 3/8” x 3/8” 3/8” x ½”
3/16” x ¼” = Neonatal Pack ¼” x ¼” = Infant Pack ¼” x 3/8” = Pediatric/Small Adult Pack 3/8” x 3/8” = Adult Pack 3/8” x ½” = Large Adult Pack
Sequence to choosing an appropriate pediatric CPB circuit
Kg weight - based flows Weight (kg) 0-3 3-10 10-15 15-30 >30 >55
0-3 = 200 cc/kg 3-10 = 150 cc/kg 10-15 = 125 cc/kg 15-30 = 100 cc/kg >30 = 75 cc/kg >55 = 65 cc/kg
Terumo Baby RX05 (Max Flow and Prime volume)
Max Flow: 1.5 L/min (in red)
Prime volume: 43 cc (in red)
Terumo RX10
Max Flow: 4 L/min
Prime volume: 135 cc
-used for bigger kids
Terumo RX15
Max Flow: 5 L/min
Prime volume: 135 cc
-used for bigger kids
Sorin Kids D100
Max Flow: 0.7 L/min
Prime volume: 31 cc (in red)
Sorin Kids D101
Max Flow: 2.5 L/min
Prime volume: 87 cc
Stroke volume/ revolution for boot diameter: 3/16” ¼” 3/8” ½”
3/16” = 7 cc
¼” = 13 cc
3/8” = 27 cc
½” = 45 cc
do NOT exceed how many RPM’s for maximum tubing flows
100 RPM’s
Max tubing flows for: 3/16” ¼” 3/8” ½”
3/16” 7 cc => (x 100 =700 cc)
¼” 13 cc => (x 100= 1300 cc)
3/8” 27 cc => (x 100= 2700 cc)
½” 45 cc => (x 100= 4500 cc)
Reynolds number
Reynolds number = (velocity of fluid x density of fluid x diameter of pipe) / viscosity of fluid
Poisueille’s law
how does turbulent flow effect the critical velocity
Choosing arterial tubing size base on max blood flow and how much prime it contains 1/8 3/16” ¼” 3/8”
1/8 => 700 mls/min => 3 mls/ft
3/16 => 1100 mls/min => 7 mls/ft
1/4 => 2000 mls/min => 10 mls/ft
3/8 => 6500 mls/min => 20 mls/ft
why is venous line normally larger
Choosing arterial tubing size base on max blood flow and how much prime it contains 3/16” ¼” 3/8” ½”
3/16 => 1100 mls/min => 7 mls/ft
1/4 => 2000 mls/min => 10 mls/ft
3/8 => 6500 mls/min => 20 mls/ft
½ = > ———- => 40 mls/ft
Resistance in the venous reservoir
Pediatric Cannula Selection
Pediatric Cannula Selection: arterial
Aim: utilize the smallest cannula w/ the highest flow rate
Do NOT exceed pressure drop > 100 mmHg
Critical velocity is reached when laminar flow becomes turbulent (Reynolds #)
Higher pressures = higher sheer stress = hemolysis = bad
Pediatric Cannula Selection: venous
Aim: drain the patient with the smallest cannulas
Be aware if the cannulation is bicaval or single atrial cannula
Pressure drop is in the -30 to -40 range (pressure-flow curve)
Vacuum Assist Venous Drainage (VAVD) may help but at a cost (micro-emboli may be associated with VAVD)