5 unit 2 Foundations of Perfusion Technology and Techniques (1).pptx

Perfusion Program Foundations of Perfusion Technology & Techniques What we will cover: Unit 2 - Tubing used in the ECC Connectors Sterility Surface Modifications Tubing in the Extracorporeal circuit Tubing in the ECC • Polyvinylchloride (PVC) is the predominant tubing material used today in ca...

Perfusion Program Foundations of Perfusion Technology & Techniques What we will cover: Unit 2 - Tubing used in the ECC Connectors Sterility Surface Modifications Tubing in the Extracorporeal circuit Tubing in the ECC • Polyvinylchloride (PVC) is the predominant tubing material used today in cardiopulmonary bypass, but latex rubber and silicone rubber are other options • PVC is made up of polymer chains with polar carbon-chloride (C-Cl) bonds • These bonds result in considerable intermolecular attraction between the polymer chains, making PVC a fairly strong material • On its own, PVC is a rigid plastic, but plasticizers are added to the type of tubing used in a circuit, which make it malleable and easier to manipulate • What is a Plasticizer? • a plasticizer is a low-volatility liquid or solid substance that’s added to a raw polymer like a type of plastic or rubber to improve its flexibility, make it easier to shape and mold, and reduce friction on its surface • When they’re added to a polymer, they work themselves into the polymer chains, acting like a Ref: buffer between the segments of Advancedplastiform.com molecules Over 30,000 substances have been tested for use as a polymer plasticizer, though today, only about 50 are available for use. Of these, they are divided into four families: •Phthalates, which are used for flexibility in plastics. •Dicarbonates are used in shaping PVC at lower temperatures. •Phosphates are used to make a material flame retardant. •Fatty acid esters are added to rubber and vinyl to improve flexibility. Tubing in the Extracorporeal circuit •Plasticizers • There are over 8 million tons of plasticizers used each year, and most of those are added to polyvinyl chloride (PVC) • Consider PVC for a moment – it ranges from a hard, rigid, brittle material used in water and sewer pipes, but it’s also used to make shower curtains, flexible tubes, and cable covers • Without the plasticizers (most often, phthalates and fatty acid esters), PVC would stay in its hard, rigid form. • Are Plasticizers safe? • Studies related to how they affect the environment, whether phthalates permeate indoor dust, and whether endocrine disruption from phthalate exposure is a factor to be concerned with, have all been performed • The Registration for Evaluation, Authorisation, and Restriction of Chemicals (REACH), which is known to be the most comprehensive and strict safety regulating organization in the world, has determined that nearly all plasticizers are safe, and so has the FDA. Ref: Advancedplastiform.com Tubing in the Extracorporeal circuit Silicone Rubber *Silastic tubing: medical grade silicone tubing • Silicone rubber is a semi organic synthetic • Its structure consists of a chain of silicone and oxygen atoms rather than carbon and hydrogen atoms, as is the case with other types of rubber • The molecular structure of silicone rubber results in a very flexible but weak chain • Silicone produces less hemolysis than PVC when the tubing is occluded but can release more particles • Silicone rubber is sometimes utilized in the arterial pump roller head as an alternative to commonly used PVC tubing Tubing used during CPB is subject to repeated compression in pump roller heads. This intermittent compression can degrade the integrity of the walls of the tubing and may cause plastic micro particles to Tubing in the Extracorporeal circuit Tubing in the ECC • Tubing can be made with a biocompatible coating (see Table 2.2), which may help reduce the inflammatory response to foreign material • Sequelae from the inflammatory response include platelet activation, initiation of the coagulation cascade, decreased levels of circulating coagulation factors, activation of endothelial cells and leukocytes, releasing mediators that may Tubing in the Extracorporeal circuit Tubing in the ECC • One type of circuit coating uses both hydrophobic and hydrophilic properties to form a new layer on top of the tubing that reduces protein denaturation and platelet adhesion • coating is made from a non-heparin-based biopassive polymer Poly(2methoxyethylacrylate) (PMEA), this tubing can be used on heparin sensitive or intolerant patients • (ex. Terumo X-coating) • Another type of biocompatible tubing is made from phosphorylcholine that mimics the natural endothelium to reduce platelet activation and cell adhesion to the tubing surface. (ex. Liva Nova PHISIO coating) • Regardless of the type or manufacturer selected, biocompatible tubing can improve platelet preservation and reduce the inflammatory *When referring to tubing in the Perfusion realm, ID is implied. That’s why connectors of the same size look smaller than the body of the tubing* Tubing in the Extracorpor eal circuit • Selection of appropriate tubing size is based on the application • Larger bore tubing requires less pump head revolutions needed to displace the same amount of volume as smaller tubing, meaning less mechanical stress from repeated compression • The internal diameter as well as the length should be carefully considered as both will affect the priming volume • While a larger internal diameter allows for greater flow at lower pressures, it has a higher prime volume, increased contact activation, less resistance, and a larger pressure gradient (ie pressure drop) • Wall thickness: most commonly used in Perfusion: 1/16’’: more flexible, pliable. Higher potential for kinking. 3/32’’: less flexible, better strength, less potential for kinking. Tubing in the Extracorporeal circuit Tubing in the ECC • Many factors to consider when selecting the best fit for the application required (see Table 2.3) • When deciding upon the size of arterial and venous tubing, the patient’s body surface area (BSA) and calculated cardiac index can help guide the appropriate size of tubing • DO2 (ie goal directed Perfusion) • Tubing for cardioplegia administration is based on the solution being used, the ratio of blood to crystalloid needed, and the type of delivery device • When choosing tubing for scavenging blood from the surgical field and venting of the heart or aorta, the decision is usually based on institutional protocol, but will take into account the volume of the tubing length and the displacement per revolution of the pump head. • This is part of the tubing pack that is pre-determined Tubing in the Extracorporeal circuit ”Medical” Tubing • This designation, “Medical Tubing” typically comes through standards or certifications which dictate material and specification requirements for tubes • Medical device manufacturers can’t avoid regulatory procedure while manufacturing the device, US FDA keenly verifies the product’s safety and effectiveness. • Medical tubing may require many different features depending on the specific application • Most notable is opacity, which defines the ability to seethrough the tube • Clear tubing is important for tubes used to handle fluid delivery in order to track fluid movement and account for possible air bubbles in the system • Other features include serializability, the ability to coil the tubing for storage or transport, and spark or static resistance. Tubing in the Extracorporeal circuit Tubing in the ECC • On the basis of material, the Medical tubing market is segmented into PVC, polyolefin, TPE & TPU, silicone, and others TPE • Thermoplastic Elastomer (TPE): easy to sterilize and offers excellent cleanliness properties – lower temperature resistance, chemical resistance and worse form recovery (compression set) after being under load. TPU • Thermoplastic Polyurethane(TPU): Not rigid enough for some industrial applications. Absorbs surrounding moisture (hygroscopic) • Silicone can be used (ex. Silastic tubing) – again, based on intended application • Polyolefin tubing: a highly flexible heat shrink tubing with a low shrink temperature and excellent abrasion resistance • thin wall heat shrink tubing: will insulate, identify, bundle, protect and repair a wide variety of electrical, Polyolefin Silicone Tubing in the Extracorporeal circuit Manufacturing Process • PVC is the most popular material for medical tubing, accounting for approximately 30 percent of the market • The two methods for the manufacture of plastic tubing are Extrusion and Pultrusion • Extrusion: several steps to the extrusion process • The main ingredient is a polymer resin, which is referred to as nurdles, pellets, granules, flakes, or powder, that are fed into a hopper mounted on the extruder’s barrel • The resin descends the feed throat of the hopper into the barrel that has a screw that moves the resin toward the die • During its movement down the barrel, pushed along by the screw, the resin is slowly heated to a melting temperature • Extrusion uses highly technical equipment to control the temperature, speed, force, tension, and time of the process. Medical tube extrusion line with bubble (production startup) Tubing in the Extracorporeal circuit Manufacturing Process • The two methods for the manufacture of plastic tubing are Extrusion and Pultrusion • Pultrusion: like extrusion, is a continuous feed process used to produce a tubing profile • Unlike extrusion, pultrusion pulls reinforced fibers that have been wetted in a thermoplastic resin through a die • Polymerization happens as the fibers go through the die • Pultrusion is a low maintenance and efficient method for producing plastic tubing that is corrosion resistant as well as having low thermal conductivity. Pultrusion, how it works - Epsilon Composite Tubing in the Extracorporeal circuit Tubing Performance Specifications 1. Medical tubing performance is rated based on a number of performance specifications given by the product manufacturers. 2. Pressure rating defines the minimum or maximum pressures the tube is designed to withstand, measured in pounds per square inch (psi). 3. Maximum vacuum defines the maximum vacuum pressure that can be created in the tube, most frequently given in inches or millimeters of mercury, referenced below one standard atmosphere. 4. Minimum bend radius is a rating based on the acceptable amount of deformation the tubing cross-section can undergo, typically given in inches or millimeters. The smaller the minimum bend radius, the higher the tube flexibility. Flexing the tube too far can cause kinking or permanent deformation, which can be especially dangerous in medical applications. 5. Temperature range defines the full range of ambient temperatures that the tubing is designed to operate within. Tubing in the Extracorporeal circuit Connections • How do we make connections with tubing when it needs to be cut to specific length? • Connector: polycarbonate connectors most widely used • Rigid, non-flexible, high strength, heat/cold resistant • Same material as venous hardshell reservoirs • Custom made to various size tubing ( ID size) • Connector: name also referred to as “fitting” • Connectors seen in other medical uses (drains, etc) often made with polypropylene: not as strong as polycarbonate, less heat/cold resistant. Tubing in the Extracorporeal circuit Connections • Often, site-specific instructions for custom tubing packs will include request for the manufacturer to pre-connect tubing within the ECC. • Connections can be “hand placed”, and able to be removed by the Perfusionist later if needed • Connections can be “bonded”, which is performed by heating the tubing and placing it on the specified connection site so that the tubing “bonds” and seals to the connector site, rendering it impossible to be handremoved • Can only be removed by cutting tubing • Tie-banding can also be used on tubing Tubing in the Extracorporeal circuit Sterilization • How do we sterilize tubing? • Ethylene Oxide "Gas" Sterilization • ETO is a colorless gas that is flammable and explosive • The four essential parameters (operational ranges) are: gas concentration (450 to 1200 mg/l); temperature (37 to 63°C); relative humidity (40 to 80%)(water molecules carry ETO to reactive sites); and exposure time (1 to 6 hours). These influence the effectiveness of ETO sterilization • The basic ETO sterilization cycle consists of five stages: • • • • • preconditioning and humidification gas introduction exposure evacuation air washes takes approximately 2 1/2 hrs excluding aeration time **Mechanical aeration for 8 to 12 hours at 50 to 60°C allows desorption of the toxic ETO residual contained in exposed absorbent materials Tubing in the Extracorporeal circuit Sterilization Ethylene Oxide Sterilization is Best Suited For: •Polymer resin-based products. •Single-use medical devices. •Procedure kits. •Surgical trays. •Synthetic gowns. •External terminal sterilization of sealed combination drug devices (filled syringes, drug-coated stents) TOXICITY Specifically, ethylene oxide is classed as a germ cell mutagen, a carcinogen and a reproductive toxin. The EU set out its maximum residue levels (MRLs) for ethylene oxide in a range of foods and products in regulation (EC) No 396/2005 and its subsequent amendments. These levels vary from 0.02mg/kg to 0.1mg/kg, depending on the nature of Tubing in the Extracorporeal circuit •Sterigenics Operation • Atlanta, Ga (Vinings and Smyrna area) Tubing in the Extracorporeal circuit