Chapter 13 Aseptic Technique By the end of this chapter, you will be able to: l Define the term closed procedure l Explain what is meant by air flow/air stream and give examples of product positioning l Explain how sterility of products can be maintained l Define the term aseptic technique Introduction This chapter will give you a brief overview of some of the aseptic techniques necessary to maintain product sterility. It also includes a number of aseptic manipulation videos for you to watch in the activities section. What Can Go Wrong l Infusion-associated septicaemia can be a life threatening hazard to patients. l In fact microbial contamination of injectable products, cytotoxic syringes and Parenteral Nutrition bags have all been implicated in the deaths of patients. l In nearly all examples, the contamination resulted from operator error or ignorance. Sterility of products can be maintained by a combination of human activities, meticulous preparation and the appropriate use of equipment. Information: The correct operator technique to maintain sterility of products is called Aseptic Technique. Contamination In a study from 2001 showing bioburden of cleanroom items: items ready for transfer were contaminated with bacteria before disinfection and some items were contaminated with bacterial spores, these included syringe and needle packaging, swab packaging and sharps bins. Therefore using the correct disinfection method is an essential part of the aseptic process-see Chapter 12 Transfer Procedures for more detailed information. Chapter 13: Aseptic Technique 1
Aseptic Processing Accidental contact with surfaces Remember that leaning on walls and benches can introduce contamination. Touching surfaces unnecessarily and without thinking is very easy to do. Also using gloved hands to scratch an itch or rub an eye for example, will contribute to contamination which will then be spread about unconsciously. Avoid contact with the HEPA filter It is essential to avoid all contact with the HEPA filter and mesh. Filters can be damaged by aspirates from syringes and vials, fragments of glass, and fluid from alcohol sprays. Avoid touching the filters when cleaning and working close to them. Contact with the HEPA filter can cause damage and therefore failure of the air quality. Work flow Work should be carried out in a neat and orderly manner. To reduce and avoid contamination; keep the work area free from clutter, dispose of waste carefully and don t allow the build up of paper waste. Remember to work following a pattern and use a work flow which avoids confusion, i.e. work from left to right. Equipment Syringes Syringe size should be selected according to the volume of liquid to be measured. To ensure accuracy use the smallest size syringe possible to measure the volume required i.e. if a 2.5ml volume is needed a 3ml syringe (not a 5ml or 10ml syringe) should be used. Graduations on syringes vary according to syringe size, from 0.1ml to 5ml. For accurate dispensing the appropriate syringe must be used. Occasionally, a specific syringe size will be specified on a worksheet. This is usually when the syringe is to be placed in a syringe driver during drug administration. Syringes are commonly available in sizes ranging from 0.5 to 60 millilitres Syringes come with luer-slip or luer-lock connections. To maintain sterility, the syringe tip and plunger should not be touched Correct handling Incorrect handling Syringes are used to measure liquids. They can be used for aspiration or injection of fluids or as final containers for single doses. Syringes can be sealed using a syringe cap. 2 Chapter 13: Aseptic Technique
Chapter 13 Aseptic Technique Over extension of syringes Take care to avoid over extending the plunger, as the further the plunger is extended beyond the barrel the more pressure is put on the seal or grommet. If this seal is broken or becomes damaged during manipulations, the sterility of the product cannot be guaranteed. In this image we can clearly see some of the injection solution visible between the seals. In this case the product will be rejected. A special silicone lubricant ensures the plunger moves smoothly and evenly in the barrel. The seal or grommet is usually made of latex free material. Needles Coring is where small pieces of bung are cut out by the needle point during insertion into vials, bottles and additive ports. This becomes particulate matter in the finished product which will result in the product being rejected for use. To preventing coring: l Insert needle bevel slope at right angles to the stopper surface l Push smoothly down l Bevel tip and heel enter at same point l Do not twist or use a corkscrew action Needles and packaging are colour coded for easy recognition Needle shafts are usually made from medical stainless steel and are lubricated with a sterile coating. Always manipulate needles by their protective covers and never touch any part of the needle itself. Needle gauges This image shows how gauges differ-the lower the gauge number, the thicker the needle shaft. The sloped surface of the bevel end of the needle creates a sharp tip which allows a smooth insertion into bungs and caps with minimal coring. Two numbers are often used to refer to needle size. One measures gauge and the other length. The gauge of the needle corresponds to the diameter of the needles bore and ranges from 27 (finest) to 13 (largest). Chapter 13: Aseptic Technique 3
Aseptic Processing Filters The purpose of filtration is to reduce the number of particles that may produce adverse effects or to reduce the bio burden, and to achieve or ensure sterility. Manipulations in aseptic procedures may introduce significant numbers of particles, such as: l Rubber fragments from bungs l Glass from ampoules l Silicone lubricant droplets from syringes There are different filter sizes available: l 5 micron filter needles, straws and disks are used to filter out particles from solutions l 0.2 micron disk filters are used to sterilise solutions and are used in venting pins, mini-spikes and dispensing devices to sterilise the air Using Filters Solutions should be withdrawn from vials and ampoules using a simple needle-but pushed into the final container through a filter which replaces the original needle on the syringe. If a solution being added to a bag or bottle was removed from an ampoule, or from a vial made up from a powder, use of a filter is advised. This could be a 5 micron filter needle or a small 0.2 micron disk filter. If venting pins are used in vials to allow pressure equalisation, ensure the venting pin is in the air space as diluent is added to powder. If the solution wets the filter it becomes blocked and no longer allows air to pass through it. Glass ampoules Glass ampoule design There are two designs of ampoule. The majority have an etched line around the neck which gives a weak point for snapping the ampoule open. The other design is known as point-break. 4 Chapter 13: Aseptic Technique
Chapter 13 Aseptic Technique Point-break ampoules have no etched line but have an ink blob or spot on the neck. Pressure applied to this spot or blob will cause the ampoule to open cleanly. Always open point-break ampoules away from the ink spot. Important: If you try to open this type of ampoule incorrectly, there is a higher risk of injury from broken glass. Always snap away from body towards the source of sterile air. Infusion bags and bottles Infusion bags In an isolator the ports should be placed facing towards you and in a laminar flow cabinet, the ports should be at right angles to the filter face. Always ensure that the additive port is fully extended and supported whilst injecting into the bag to avoid punctures and to keep the port well clear of the work surface. Sterile wipes can be used to protect the operator from glass shards if required. Remember to check gloves after opening a glass ampoule in case of tearing. Drawing up solution from a glass ampoule Correct way to remove liquid from glass ampoule is to gently tilt the ampoule so the solution pools in the upper corner where the tip of the needle is placed. Needles are pushed through the bung of the additive port in a simple straight push -avoid twisting or jerky actions as these increase the risk of coring. Carefully insert the needle into the centre of the additive port, push in sufficiently to clear the port bung but not so far as to risk puncturing the tubing or bag. Bottles Remove protective caps before sanitisation and transfer. Swab rubber closure with sterile 70 % alcohol wipe using a firm stroke and allow to dry. Many bottles have indentations in the rubber closures which need to be wiped thoroughly and allowed to dry. Chapter 13: Aseptic Technique 5
Aseptic Processing Position so that the rubber closure is in the sterile air stream Other techniques Other actions to take to apply good aseptic technique are shown below: Positioning Insert needles or spikes into the marked circles on the rubber closure of the bottle. These circles have a reduced thickness to allow easier access. Ensure pressure is equalised when adding solutions to bottles, to prevent positive pressure developing inside the bottle. Seal bottles with an additive seal. (If the bottle is to be the final container for the product) The no touch technique The most basic principle for aseptic technique is no touch. Position needles, syringes and vials mid air and point them upwards within the air stream. Position your hands so that the latex or rubber bung is in the direct air stream and is above the turbulence associated with the bench surface. DO NOT reach across or cross your arms in the critical work areas. Hand position is very important in order to achieve the no touch technique. Work should be positioned mid air wherever possible in an unobstructed airflow. (This gives the best laminar airflow). Fingers, loose clothing (cuffs and folds) should be kept well away from the working area within the critical zone (i.e. the injection point and needle tip). Large bags should be positioned sideways to the airflow, so that the critical zone (the bung) is in unobstructed air. 6 Chapter 13: Aseptic Technique
Chapter 13 Aseptic Technique Hang large containers from the rail to gain the advantage of the air flow. Technique When withdrawing liquid from a bag, gently squeeze the bag whilst withdrawing the fluid to avoid straining your hands and wrists Ensure bare or exposed needles do not have contact with any surface as this may contaminate them. The best practice is to ensure that all additions are made in mid air or at least 5cm (2 inches) away from any surface. Over-wrapped items should be peeled and not torn open. Applying a cap The overwrap can be used to contain a cap until it is needed and also to apply the cap. Image supplied by Helapet Ltd Vent vials slowly to prevent aerosol spray of contents. Caps should be tightened in one action only, twisting the cap and the syringe at the same time. Chapter 13: Aseptic Technique 7
Aseptic Processing Hold the sides of the syringe cap when you apply pressure to cap the needle. A tiny air bubble is advisable in the neck of the syringe to prevent liquids from tracking into the screw thread of the closure. (The neck of the syringe is also referred to as the luer connector). Tubing Closed procedures In aseptic preparation, closed procedures are used wherever possible. A closed procedure is when the product is prepared by transferring sterile ingredients or solutions to a pre sterilised container. This is done either directly or using a sterile transfer device without exposing the solution to the external environment. The use of a solution from a sealed ampoule can be regarded as a closed procedure when a single withdrawal is made immediately after opening, using a sterile needle or equivalent. Needles should be capped. Closures should be sealed at the earliest opportunity. Only draw up from an ampoule once If an open procedure is to be used then the standard of environment (e.g. Grade A) at the point of fill is particularly critical. Tubing should be cleared of any excess fluid before being clipped or heat sealed. Tubing should not be cut before an effective seal has been applied. 8 Chapter 13: Aseptic Technique
Chapter 13 Aseptic Technique Activity Make sure you watch the following videos at http://www.medslearning.leeds.ac.uk/pages/ aseptics/videos.html and then refer to your local procedures: l Cap and uncap a needle video 8 l Capping a syringe video 9 l Open a syringe and add a needle video 10 l Remove bubble from a syringe video 11 l Opening a glass ampoule video 12 l Opening a plastic ampoule video 13 l Draw up from an ampoule video 14 l Reconstitute from a vial video 15 l Draw up after mixing video 16 l Add fluid to an infusion bag video 17 l Removing fluid from infusion bag video 18 l Change a needle and add to infusion bag video 19 l Reconstitution of Ceftazidime video 20 If there are any variations in your local procedures, make a note of them below and discuss with your supervisor. Procedure Local Variation Chapter 13: Aseptic Technique 9
Aseptic Processing Questions Q1 How can sterility of products be maintained? (3) Q2 What does no touch technique mean? Give 4 examples of actions to take to achieve no touch. Explanation of no touch technique: Examples of actions to take: 1. 2. 3. 4. 10 Chapter 13: Aseptic Technique
Chapter 13 Aseptic Technique Q3 Why is it advisable to leave a tiny air bubble in the neck of the syringe? (1) Q4 What is a closed procedure? (4) Chapter 13: Aseptic Technique 11
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