Roller pump

roller pump

1. BY DR.VIJAYANAND PALANISAMY ROLLER PUMP

2. TOPICS Ideal characteristics of blood pump Types of Blood Pumps Roller pump History Structure – tubing Types of roller pump Principles of operation & Flow determinants Adjustment of occlusion Advantages / disadvantages Various types in use Nonocclusive roller pump

3. Ideal characteristics of blood pump move large volumes of blood (up to 7 L/min) against significant pressures (perhaps up to 500 mm Hg proximal to the arterial cannula ) pump should minimize flow velocity so that damage to the blood is minimized should not damage the blood cells and should not activate either the inflammatory or coagulation cascades

4. D esign should be simple and free from dead spaces and recesses to avoid stagnation and turbulence. Calibration of the pump should be easy, reliable , and reproducible. The pump should be automatically controlled and operated for routine use, designed for possible manual operation in case of power failure

5. Types of Blood Pumps Kinetic Pumps Centrifugal pumps Positive Displacement Pumps: Rotary Pumps

6. Positive Displacement Pumps This type of pump moves blood forward by displacing the liquid progressively, from the suction, to the discharge opening of the unit

7. Roller pumps Use rollers along flexible tubing to provide the pumping stroke and give direction to the flow This type of positive displacement pump can be set to provide pulsatile or non-pulsatile (laminar) flow .

8. History first patented in 1855 by Porter and Bradley

9. In 1887, Allen patented a pump designed for blood transfusion In 1934, DeBakey et al. made a modification to the Porter-Bradley infusion pump to prevent creepage of the latex rubber tubing during blood transfusion. added a flange to the outer circumference of the tubing, which was then clamped into the housing 1959, Melrose proposed a more advanced design, in which the roller ran along the tubing held in place by a grooved backplate

10. Patent drawings showing the modification of DeBakey and Schmidt to the rotary pump .

11. Structures Roller pumps contain a length of tubing located inside a curved raceway This raceway is placed at the travel perimeter of rollers mounted on the ends of rotating arms These arms are arranged in such a manner that one roller is compressing the tubing at all times.

12. Tubing T hree basic materials currently used for tubing: silicone rubber , latex rubber, and polyvinyl chloride (PVC )- most widely used ( durability and acceptable hemolysis rates)

13. H emolysis Latex rubber > PVC > silicone rubber PVC tubing stiffens during hypothermic CPB and tends to induce spallation,. Silicone rubber > PVC

14. Because one of the two rollers is always compressing the tubing, the double-roller pump generates a relatively nonpulsatile flow . Debate over the advantages and disadvantages of non-pulsatile or pulsatile perfusion during cardiopulmonary bypass still continues

15. Principles of operation roller pump causes blood to flow by compressing plastic tubing between the roller and the horseshoe-shaped backing plate as the roller turns in the raceway Flow from a systemic roller pump is linear with rpm The stroke volume, or output in milliliters per rpm , of a roller pump can vary slightly depending on tubing material, elasticity, or temperature but generally ranges from 12.7 (1/4-inch ID tubing) to 41.9 mL (1/2-inch ) when using a 6-inch dual roller pump

16. Flow determinants pump head and tubing diameter, roller RPM, and length of tubing in contact with the rollers Roller pumps are relatively independent of circuit resistance and hydrostatic pressure

17. Forward or retrograde flow of blood can be achieved by altering the direction of pump head rotation; thus roller pumps are commonly used as the primary arterial flow pump as well as for suction of blood from the heart and mediastinal cavity during CPB to salvage blood , to deliver cardioplegic solution

18. Adjustment of occlusion Roller pumps require occlusion adjustment for optimum function and avoidance of hemolysis and activation of leukocytes and platelets Occlusion - separation between the rollers and the backing plate (or raceway) Total occlusion is not used Excessive compression aggravates hemolysis and tubing wear; too little occlusion may also aggravate hemolysis

19. conventional method for setting occlusion holding the distal systemic flow line, which is primed with clear fluid, vertically so that the top of the fluid column is 30 to 40 inches above the pump. The occlusion is adjusted until the fluid level falls at a rate of 1 inch/min .

20. alternative methods (i) clamping the outlet tubing from the roller pump and slowly advancing the rollers to pressurize fluid within the line, stopping the pump, and then adjusting the occlusion until a slow decline in pressure monitored distal to the pump head is observed; and (ii) clamping the distal tubing and adjusting the occlusion while slowly rotating the pump head so as to maintain pressure in the tubing greater than that anticipated during CPB (e.g ., 300 to 400 mm Hg); this method requires a valved shunt between the outlet and inlet tubing of the pump

21. For suction or vent pumps, the occlusion is set by clamping the tubing on the inlet side of the roller pump and gradually occluding the rotating rollers until tubing within the pump head just collapses . When occlusion is properly set, the pump flow rate does not significantly decrease as the afterload (arterial pressure) increases

22. Occlusion settings Hard : •Descent rate< 0-1 cm/min 5 RPM against occlusion = > 350 mmHg Medium: Descent rate 2-3 cm/min 5 RPM against occlusion = 250 - 350 mmHg Light: Descent rate 4-10 cm/min 5 RPM against occlusion = 200 - 250 mmHg

23. Advantages Out put is accurate because it is not dependent of the circuits resistance ( including the patients resistance ) Occlusive, therefore if power goes out the arterial line won’t act as a venous line

24. Disadvantages/ Complications malocclusion (over- or underocclusion ), miscalibration , fracture of the tubing, "runaway" pumping , loss of power, spallation, and the capacity to pump air(Cavitation ) High RPM and fully occlusive settings tend to promote blood damage

25. spallation which refers to the release of plastic microparticles from the inner wall of tubing as a result of roller pump compression

26. cavitation sudden occlusion of the inflow to the pump, as a result of low circulating volume or venous cannula obstruction, can result in “cavitation,” the formation and collapse of gas bubbles due to the creation of pockets of low pressure by precipitous change in mechanical forces. pressure-regulated shunt between the outflow and inflow lines of the roller pump However , this usually does not occur because the tubing that enters the roller pump is short and is connected directly to a reservoir that contains enough blood to preclude development of significant negative pressure

27. Rawn et al. found no difference in hemolysis between a roller pump with a standard set occlusion and a centrifugal pump at a 4.5-L/min blood flow rate with an afterload of 250 mm Hg. When the occlusion is opened such that pumping at 5 rpm against occluded tubing maintains a pressure of 150 to 225 mm Hg, the roller pump induces less hemolysis than a centrifugal pump

28. Advantages Power leads accessible from front Easy to operate alarm status Delayed reversing Clutchable hand cranking Easy to wheel Can hand crank with lids closed Alarm status turns off both main & cardioplegia Sarns 8000 Disadvantages Hinge occlusion mechanism - not as secure as COBE Bulky Tilted operating panels (if spill) Individual collars

29. Advantages Compact design Easy to operate alarm status Difficult to wheel Disadvantages Difficult to access power outlets Computer configuration - difficult to control Non clutchable cranking Lids must be open to crank COBE

30. Advantages Rotating head turrets Disadvantages Difficult to control alarms Flat control surface - poor spill control; items could be dropped directly on & damage Opaque pump covers - difficult to see Preloading tubing line inserts (had to be initially removed) Stockert

31. Advantages Fully computerised - downloads everything Fully automated everything Runs from transformer- not so subject to current surges [converts AC to DC] Universal collars Disadvantages More complex to operate? Unique operating procedures – non intuited During failures - requires codes to be switched into manual override Non modular design - if base fails (or computer system) the whole system goes down Gambro/ Jostra

32. Flat compliant tubing is fitted under tension over the rollers. Nonocclusive roller pumps require positive pressure at the inlet to fill the tubing as the rollers turn. Macroair emboli are unlikely. Nonocclusive roller pumps require use of an in-line flowmeter Nonocclusive roller pumps

33. Metaplus pump is a new type of blood pump that appears to incorporate some advantages of a centrifugal pump while minimizing some disadvantages of a conventional roller pump This pump will not drain the venous reservoir, will not create negative pressure and cavitation, will not overpressurize , and will not allow retrograde flow Metaplus pump

34. Forward fluid flow is accomplished by a passive-filling tapered pumping chamber fabricated of two sheets of flat polyurethane tubing bonded at the edges pump chamber segment is stretched under tension over three rollers. no backing plate against which the tubing can be compressed with rollers . The rollers are mounted on a rotor that spins to impart a peristaltic action on the fluid within the pump chamber priming volume is 120 mL Structure and functioning

35. Schematic drawing of nonocclusive roller pump

36. 1. LeGallois JJC. Experiments on the Principle of Life (tr. by NC and JC Nancrede ). Philadelphia, M. Thomas, 1813. 2. von Frey M, Gruber M. Untersuchungen uber den stoffwechsel isolierter organe. Ein respirationsapparat fur isolierte organe. Arch f Physiol (Leipz.) 1885; 9:519. 3. Gibbon JH. Artificial maintenance of circulation during experimental occlusion of pulmonary artery. Arch Surg 1937; 34:1105. 4. Gibbon JH. Application of a mechanical heart and lung apparatus to cardiac surgery. Minn Med 1954; 37:171. 5. Andreasen AT, Watson F. Experimental cardiovascular surgery. Brit J Surg 1952; 39:548. 6. Andreasen AT, Watson F. Experimental cardiovascular surgery: Discussion of results so far obtained and report on experiments concerning donor circulation. Brit J Surg 1953; 41:195. 7. Lillehei CW. Controlled cross-circulation for direct-vision intracardiac surgery: Correction of ventricular septal defects, atrioventricularis communis and tetralogy of Fallot . Postgrad Med 1955; 17:388. 8. Lillehei CW, Cohen M, Warden HE, Read RC, Aust JB, DeWall RA, Varco RL. Direct vision intracardiac surgical correction of tetralogy of Fallot , pentalogy of Fallot and pulmonary atresia defects. Report of first ten cases. Ann Surg 1955; 142:418. 9. Dale HH, Schuster EA. A double perfusion pump. J Physiol (London) 1928; 64:356. 10. Galletti PM, Brecher GA. Heart-Lung Bypass: Principles and Techniques of Extracorporeal Circulation. NewYork , Grune & Stratton, 1962. 11. Beck A. Zur Technik der bluttransfusion. Klin Wschr 1924; 2:1,999. 12. Issekutz BV. Beitrage zur wirkung des insulins. I. Insulin-Adrenalin Antagonismus . Biochem Ztschr 1927; 183:283. 13. Bayliss WM, Muller EA. A simple, high speed rotary pump. J Scient Instrum 1928; 5:278. reference

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