Oxygenators

Cardiopulmonary bypass oxygenators-history,types,function

1. OXYGENATORS By Dr.VASANTHI DNB-CARDIAC SURGERY MADRAS MEDICAL MISSION

2. History Non membrane oxygenators : 1955 Lillehei / Dewall - 1 st bubble oxygenator ewith helix reservoir 1956 Kay/Cross – disk oxygenators 1962 cooley / beall – commercially available disposable bubble oxygenator 1966 D ewall / Najafe / Roden – 1 st disposable hard shell oxy with bulit in heat exchanger

3. MEMBRANE OXYGENATORS : 1955 KOLFF/BALZFER oxygenated blood through polyethylene membrane(animals) 1958 – Clowes – teflon as membrane plate oxygenator 1971 – kolobow –silicone membrane sheets 1985 J & J - 1 st hollow fibre polypropylene oxy

4. IDEAL OF AN OXYGENATOR Safe and efficient Overcome barrier of diffusion distance Minimum trauma to blood cells Small priming volume Easily assmebled Minimize air embolism

5. Gas transfer is proportional to partial pressure difference and surface area and inversely proportional to diffusion distance.

6. Mechanism oxygenator – blood and gas flow direction will be perpendicular

7. Bubble oxygenator 3 components : Oxygenation chamber Defoamer Arterial reservoir

8. 1.Oxygenation chamber Bubble size - determined by disperser by Orifice diameter, Gas flow rate, Blood viscosity, Surface tension. sparging plate – polycarbonate plate perforated with holes of precise dimension or porous silicate Purpose : break the bulk gas into small bubbles to allow gas exchange

9. More the no.of bubbles- greater efficiency of oxygenation Co2 diffusion is 25times > o2.Larger bubbles will efficiently remove of co2 Smaller bubbles will efficiently oxygenate but poor in removal of co2 Size : 3 — 7 mm to optimise both CO2 & O2 gas transfer

10. 2.Debubbling/ defoaming area Made up of Polyurethane or polyester (125-175microm) Beads, sponges(polyurethane),shreds, meshes, fabrics Coated with Silicon(antifoam ) reduces surface tension of bubbles & prevents bubble formation . Hence air embolism prevented

11. 3. Arterial reservoir :Always positioned after the defoaming area

12. Advantage : easy to assemble, lower cost, small priming vol , adequate oxy capacity Disadvantage : microemboli , blood cell trauma, destruction of plasma protein due to gas interface, defoaming capacity exhausted with time ,excessive removal of co2

13. MEMBRANE OXYGENATOR

14. Configuration Scrolled envelope Hollow fibre Parellel Plate

15. Microporous membrane

16. Polypropylene is a heterogenous , microporous,hydrophobic membrane Size- 0.03 to 0.07 Um in diameter Surface is hydrophobic & the pores are so small, the blood water is not ultrafiltered ; inhibit serum leakage across the membrane

17. TRUE MEMBRANE OXYGENATOR COIL [Scrolled] TYPE : consists of silicone rubber sheets coiled in a cylindrical fashion Silicone rubber is nonporous ; there is a complete barrier between blood and gas. Eg : Sci -Med oxygenator

18. Advantages -- Able to maintain stable CO2 & O2 for long periods of time (weeks), Used primarily in ECMO Disadvantages --Costly to manufacture, High priming volume.

19. Thank u