ORIGINAL ARTICLE

Development and evaluationof a venesection and cannulationtraining manikin

Andy Levy1,2

1School of Clinical Sciences,University of Bristol, Bristol, UK2UHBristol NHS FoundationTrust, Bristol, UK

Correspondence toProfessor Andy Levy, 8 Bell BarnRoad, Stoke Bishop, BristolBS92DA, UK; andy.levy@bristolmedicalpro.com

Received 23 February 2016Revised 6 September 2016Accepted 4 December 2016Published Online First21 December 2016

To cite: Levy A. BMJ Innov2017;3:32–36.

ABSTRACTThe design and construction method of atraining manikin for venepuncture is described.Developed and refined over several years, themanikin consists of a shaped pad that thetraining partner secures during use by grippingthe handles that extend behind the elbow orforearm. A thin layer of reinforced silicone rubberis stretched over a pad of polyurethane foamthat loosely houses a length of thin-walled purelatex tubing fed with artificial blood from a bagworn around the trainer’s neck. A needle-proofshield and synthetic fur backing protect thetrainer’s arm in case of overenthusiastic or ineptneedle insertion. The whole assembly isinexpensive to make and allows the doctor/patient interaction to be closely simulated.A tourniquet can be positioned and released atthe appropriate times: the feel and movement ofa blood vessel beneath the skin to palpation andthe changes in resistance as the needle isinserted first through the skin and then into theblood vessel is highly realistic. The method forproducing the manikin, free of intellectualproperty limitations or restrictions and asummary of its use in undergraduateassessments are provided.

INTRODUCTIONIn practice it may be difficult to avoid the‘see one, do one, teach one’ paradigm forthe acquisition of new clinical skills. Itmay not, however, be a strategy bestplaced to protect patients from harm.Even for the simplest and most mundaneinterventions, such as venepuncture, it isimportant to ensure that operatives are ashighly trained as possible before allowingthem into the clinical arena. As valuableas it is for students to practice on eachother, health and safety monitors in teach-ing labs take an increasingly dim view oftraining sessions that risk vasovagal

episodes and potential head injuries. Itwas such an event that led to changes inoperating procedures at our own institu-tion. Therefore until such time as virtualtraining rigs with haptic feedback are per-fected and affordable enough to be widelyavailable, relatively basic training mani-kins for many physical skills are the onlyrecourse. In theory such manikins affordstudents the opportunity to rehearse everyelement of the techniques in question. Inpractice, such devices have many short-comings, particularly when addressingskills that necessitate manikin injuryduring routine use by cutting, suturing orneedle insertion. There is an intimatetrade-off between creating a realisticexperience for the trainee and the prac-tical consideration that if a manikin is tobe subjected to vigorous use by a class ofinexperienced and eager students, it mustbe economical enough in constructionmaterials and time to be considered essen-tially disposable.Venepuncture manikins have been

designed and built in house for trainingand used successfully in summativeexams at our institution for a decade.Over this period, over 2000 studentshave used the manikin to demonstratetheir competence at venesection or can-nulation during high-stakes assessments.Construction of the manikins is straight-forward, rapid in terms of man-hourinput and inexpensive. The manikindesign lasts for several hundred carefulvenepunctures before the skin surface istoo lacerated to be realistic.

MANUFACTURING METHODMould makingThe skin texture for the surface of themanikin was originally created by taking

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an alginate impression of a suitably large area of skinsuch as the thigh (Dental Alginate Cavex CA37(DAE150038), Minerva Dental, Cardiff, UK).Immediately after setting, an impression was taken bycoating it with a thin layer of green, low melt castingwax (Alec Tiranti, London, UK). The wax impressionwas carefully removed immediately after setting andgently pressed absolutely flat while still warm. Thewax sheet bearing the negative skin texture surfacewas fixed to a sheet of thick cardboard using brownmodelling wax (a formulation, ie, very soft at 37°C:Tiranti) and cut to the shape shown (figure 1A).Markers (arrows) and lines were added to the surfaceof the wax pattern to indicate to users the extent ofthe target area. The master pattern was then coatedwith a 2 cm thick layer of Dentstone KD plaster(South Western Industrial Plasters, Chippenham,Wilts, UK) mixed to a soft slump consistency. Aftersetting at room temperature, the wax was removedfrom the plaster mould and after drying for severalhours, the mould surface was left to absorb a coatingof petroleum jelly softened with white spirit as arelease agent. Any extra petroleum jelly was wiped offwith a cloth before use (figure 1A). Apart from the

occasional addition of a thin layer of petroleum jellyafter use, the moulds require no further care and donot wear out.

Manikin makingTwenty millilitres of Silastic 3483 (Dow Corning,South Western Industrial Plasters) with the addition ofbrown silicone pigment made by mixing red andgreen silicone pigments were mixed with Silasticcuring agent according to the manufacturer’s direc-tions (usually 5% of curing agent 83) and spread outonto the mould without prior degassing (figure 1Band C). Note that a small amount of silicone pigmentproduces a skin tone typical of Caucasians. Highlyrealistic darker skin tones are achieved by adding thesame silicone pigment at higher concentrations.Once cured, a further 20 mL of a 30 mL aliquot of

Silastic 3483 prepared as above was used to re-coatthe surface, and after 2–5 min to allow the viscoussilicone to level out somewhat, covered with a layer ofstretch polyester mod mesh reinforcement (sometimessold as power mesh/net fabric (4 way stretch), FabricLand, Bristol, UK) wide enough to allow it to wrapover two bars made of 2 mm metal core diameterpolyvinyl chloride-coated garden wire (such as Apollo2 mm from any hardware store) (figure 1D and F andfigure 2A).

Figure 1 (A) The shaped plaster skin texture mould ready foruse. (B) A thin layer of coloured silastic rubber being spread overthe base of the mould. (C) The layer of silicone rubber that istoo thin to cover the surface by gravity alone. (D) The highlyflexible trapezium of stretch reinforcement, and on the left, alength of wire to stiffen the edges of the manikin and one ofthe wooden doweling handles with beads of polyester resin ateither end. (E) The shape and dimensions of the stretch denimreinforcement for the handles and (F) the reinforcement panellying on the second coat of liquid silastic with the wirereinforcements in place.

Figure 2 (A) The stretch reinforcement folded over the wiresand in (B), the four denim handle reinforcements. (C) Thedenim reinforcements folded back around the handles and allof the elements compressed and held in place overnight byvarious fitted weights (D). (E) The microembolus filter pierced bya wire threaded through the tube and (F) the length of purelatex tubing that forms the blood vessel, attached to thepolished end of the administration tubing.

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With the garden wire in place and the stretch meshlooped over it and coated with a small amount ofSilastic 3483 left over from above (10 mL of the30 mL aliquot) to keep it in place, four reinforcementpanels of stretch denim (figure 1E) were coated with alittle Silastic 3483 and looped back over 9 mm diam-eter wooden dowels with cast general purpose polyes-ter resin studs at either end (figure 2B and C). Theassembled reinforced skin, metal wire stretchers,denim reinforcement strips and handles were com-pressed used a series of shaped Dentstone plasterweights (figure 2D) and the whole allowed to set.A standard crystalloid fluid administration set was

cut-off 60 cm from the sight chamber, the regulatorwheel removed and the cut end polished using aflame. An insulated steel wire was then fed carefullythrough the tubing to puncture the microembolus andgas embolism filter as these are designed for non-blood product infusion and can block relatively easilywhen exposed to particulate food dyes and otherdebris (figure 2E).Pure latex is the only material with sufficient

memory to re-seal itself after being punctured. A17 cm length of pure latex tubing (1/800 internal diam-eter (3.17 mm), 1/3200 walls (0.8 mm)): Grafco PureAmber Latex Tubing (Medco Supply Company,Tonawanda, New York, USA) was glued to the end ofthe administration tubing using a dab of liquid latexand the distal end of the tube tied off with a singleknot (figure 2F).The soft subcuticular tissue was made from a tra-

pezium of ∼10 mm thick flexible polyurethanefoam, 170 mm long decreasing from 110 mm inwidth to ∼60 mm. A soldering iron was used tocreate a channel in the foam and perforate it10 mm from the distal end and 20 mm from theproximal end. The latex tube assembly wasthreaded through the polyurethane foam to lieloosely within the channel (figure 3A). Theassembled ‘vein’ with its polyurethane foam bedwas then coated at the edges with a small amountof Silastic 3483 and inverted onto the back of theskin assembly (figure 3B).A strip of 25 mm wide fiberglass weave tape (East

Coast Fibreglass Supplies, South Shields, UK) wasimpregnated with polyester resin and allowed to set ina slight arc by resting it over a length of 60 mm diam-eter plastic tubing (figure 3C). Designed to protectagainst all but the most purposeful and determinedattack, the impermeable resin and fiberglass shield wasstuck convex side down between the polyurethanefoam and a panel of synthetic fur to further protectthe user (figure 3D and E). The whole assembly wasallowed to cure in a gentle arc as shown (figure 3E).Synthetic (rather than cochineal) red liquid food

dye—usually about 10 mL per 500 mL with 1 mLblack liquid ink (such as Quink, Parker Pen Company)to confer added depth of colour and opacity is

introduced into a bag of saline or dextrose. Themanikin is primed by drawing air from a centimetreor two above the distal end of the tubing (avoidingthe knot), then in use, held over the arm and forearmas shown (figure 3F). A length of ribbon allows thebag to be worn reasonably comfortably during use, sothat the teacher/assessor can wear a tourniquet, reactrealistically to all stages of the procedure, observe it atclose range and even alter the extent to which thevessel is visible and mobile by adjusting the tension onthe wooden handles.Although the manikins take up to 3 days to com-

plete using standard cure catalyst, the hands on ele-ments amount to little more than an hour of time.With fast cure catalyst (81-VF), a venesection manikincan be made from scratch within a day.A video of the procedure is available on You Tube

(https://youtu.be/fAcKqKiz96E), and a further descrip-tion of the rationale and manufacturing method is shownabout 5 min into a TEDx talk given by the author(https://www.youtube.com/watch?v=p6rXDO2ITJ0).

Figure 3 The latex tubing threaded through and lyingunrestrained in a shallow gutter formed on the surface of atrapezoid panel of polyurethane foam. The deeper the gutter,the more buried the vessel feels in the final assembly. (B) Thefoam and vessel assembly inverted onto the skin assembly usinga small amount of Silastic around its perimeter. (C) A 6 cmdiameter cylinder, coated with cling film onto which a length of25 mm wide woven fiberglass tape impregnated with polyesterresin is being allowed to set to form a slightly cylindrical needlepenetration guard. (D) The fiberglass shield glued with anotherfew drops of Silastic, and (E) the whole assembly with anadditional panel of artificial fur material allowed to set into aslight curve. The position of the finished manikin in use isshown in (F).

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EVALUATIONDeveloped through three iterations, the manikin wasused in objective, structured, clinical MB ChB finalsexams from 2003 until 2013 when this type of prac-tical assessment was deleted from the portfolio.Candidates were asked to obtain blood samples in

appropriate tubes for specific tests such as a full lipidprofile, creatinine and HbA1c. The marking scheduleaward up to 5 marks for asepsis, preparation andcommunication, up to five marks for clearing up anddisposal of sharps, through to minus 10 marks forleaving sharps out, marks for labelling and using thecorrect tubes, and 55 marks for obtaining sufficientblood at the first attempt, 25 marks at the secondattempt, 10 marks for obtaining an insufficient sampleand no marks for trying to obtain blood more than 3times, irrespective of the outcome. The pass marks forthe station varied from 50% to 58.8% and attractedvery little adverse feedback from candidates or exami-ners. Typical mark ranges over several years are shownin figure 4. In total, 2028 candidates (not includingre-sitting candidates) carried out venesection and/orcannulation using the manikin in summative, highstakes assessments.The manikin was also used in a national postgradu-

ate examination (the Bristol Foundation Assessment)to determine whether foreign graduates were suitablytrained to take up junior hospital jobs in the UK. Inthe latter assessment, it was noted that many candi-dates inserted the needle all the way to the hub whencarrying out venesection. When asked, candidates

explained that ‘that’s the only way to get blood out ofa manikin’, demonstrating the negative consequentialvalidity of some manikin designs. If manikins are tooexpensive to allow the skin to be frequently replaced,sites of multiple previous venepunctures rapidlybecome very obvious, again undermining their validityin training and summative assessments.A drawback of the present design is that when

vacuum blood collection tubes are used, a ‘miss’ willrelease the vacuum and not allow students to collect ablood sample even if they advance further towards theblood vessel and successfully enter it. The sameapplies if a student skewers the latex tube, puncturingits anterior and posterior walls and then attempts todraw blood into a vacuum tube. In this circumstance,there is a further small risk that by pulling the needleback through the vessel, some air will be introducedinto the ‘vein’. This tends to displace the blood,which can sometimes make it more difficult for thesubsequent candidates. In practice, this has rarely beenan issue not least because the manikin is automaticallyre-primed by the next (competent) user, who mightfind that the first vacuum tube does not fill com-pletely although subsequent tubes do. Finally, if partof the test protocol involves securing a cannula to theskin, this may prove more difficult than normal asSilastic is relatively non-stick compared to humanskin.

DISCUSSIONFor economic reasons, it was important at the outsetto constrain the design to address only those elementsthat are required for the skills in question to berehearsed. A forearm and antecubital fossa venesec-tion and cannulation manikin should simulate the feelof the skin and the change in feel to palpation over ablood vessel, the initial and changing resistance as theneedle is inserted, a target vessel for venepuncture ofsimilar size, depth, orientation, mobility and wallresistance to the medial cubital vein or the median orcephalic veins of the forearm, realistic flashback andflow of blood into the container/s and cessation of‘bleeding’ when the needle is withdrawn. Themanikin should also allow the hygiene elements andpsychosocial considerations of venesection to beaddressed by having the assessor/patient intimatelyassociated with the device, essentially wearing it, yetprotect the operator from injury caused by more inepttrainees, as well as allowing a tourniquet to be placedand released at the appropriate points in theprocedure.For venepuncture, the skill involves interaction with

the ‘patient’ and a practiced, fluent and effective tech-nique that is likely to cause minimal discomfort to thepatient and fills the collection tubes to their intendedcapacity with blood first time with minimal fuss is theideal.

Figure 4 Representative examples of ranked scores of theobjective, structured clinical examination (OSCE) phlebotomystation from 2003 (n=146 candidates), 2005 (n=167), 2006(n=173), 2008 (n=219) and 2010 (n=263 candidates). Markswere awarded for asepsis, preparation, communication,labelling appropriate collection tubes and disposal ofconsumables and sharps. Obtaining a blood sample first timewas awarded 55%, with an automatic fail if a candidateattempted to obtain a blood sample on more than threeoccasions. A heavy penalty was imposed for failing to disposeof needles safely.

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By making manikins in house, the pressure tomarket manikins is lifted and there is, therefore, littleneed for the manikin to be designed to be physicallyrealistic and include the shoulder and upper arm,distal forearm or palm of the hand, none of which areactually used for venesection or contribute to master-ing the techniques in question.With the exception of pure latex tubing, all of the

materials required to make the manikin are widelyavailable. Latex tubing 1/800 internal diameter(3.17 mm) with 1/3200 walls (0.8 mm) can be more dif-ficult to source and suppliers vary greatly in theirstocks. It is not easy to make in house. As far as latexallergy, the tubing is buried inside the manikin andwould not be expected to cause a problem for routineusers. Once the various components have beensourced, with a little practice, the production of avenepuncture manikin is straightforward and in mater-ial terms, very economical. The mould can be re-used

indefinitely, and although the complete manufacturingprocess takes several days, as each layer of silastic hasto be left to cure, the actual hands on time is relativelybrief.

CONCLUSIONSA cost-effective venepuncture training manikin thatexceeds the utility of commercial manikins can beeasily constructed without any specialist facilities orequipment. The manikin described has the advantageof being ‘worn’, so that all of the social and proced-ural elements of the interaction between the patientand phlebotomist can be repeatedly rehearsed withoutcausing anyone physical discomfort.

Competing interests None declared.

Ethics approval Not required.

Provenance and peer review Not commissioned; externallypeer reviewed.

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