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Welch Allyn AED 20

1. 141 mm diagonal 240 x 320 pixels VGA monochrome LCD no fixed 22 5 mm s time stamped system status events in log download to printer or computer no built in serial port for connection to a printer or computer defibrillation pads operations manual carrying case parallel communications kit PC data transfer serial communications kit IEC electrode monitoring cable AHA electrode monitoring cable cardiolog datacard trainer SmartView software SmartLink software patient simulator data printer ECG display manual override log review Welch Allyn AED 20 Supplier Web amp email Guarantee Maintenance provisions service contract will service engineer call spares availability Product Support PRODUCT SUPPORT Response Medical Equipment Ltd Bracken House Battlebrook Drive Campden Business Park Chipping Camden Gloucestershire GL55 6JX Tel 01386 841926 Fax 01386 841230 www responsemedical co uk sales responsemedical co uk 1 year yes yes 7 years 15 MHRA evaluation 04018 March 2004 Appendix Welch Allyn AED 20 MHRA Medical Device ALERT Medicines and Healthcare products Regulatory Agency Ref MDA 2003 012 ealt Issued 17 April 2003 For UT Further Information DEVICE All Biphasic Defibrillators all manufacturers PROBLEM Defibrillators that use biphasic waveforms generally require lower energy levels to achieve defibrillation than those
2. pass self test reports fail if Key is depressed while test is in progress key status is part of test none best 100 0 84 4 96 0 92 9 91 8 14 9 seconds worst 98 3 78 9 90 7 89 3 88 0 19 4 seconds 0 094 mV IEC code 1 2 wire lead II only keyed cable plug and socket 2 48 V and 2 55 V lt 1 second yes max error 5 no error no drift slight undershoot after each pulse no error 3 dB points measured at 1 and 25 Hz 4 mm at 10 and 25 Hz 8 mm at 10 Hz 10 mm at 25 Hz excellent pacing pulses counted by HR meter MHRA evaluation 04018 March 2004 Results Table Welch Allyn AED 20 Performance of batteries temperature during operation and charging 39 4 C theoretical worst case NiMH Lithium number of 360 J shocks from fully charged battery 75 201 number of 360 J shocks after low battery warning 19 13 advice on battery maintenance excellent Performance of self adhesive electrodes room 40 C 2 C temperature conditioned8 conditioned8 Impedance to 360J 0 2 ohms 0 2 ohms 0 2 ohms DC offset voltage at 5 s after three 360 J discharges 91 1 mV 79 5 mV 97 6 mV DC offset voltage at 10 s after three 360 J discharges 86 7 mV 77 7 mV 94 4 mV DC offset voltage at 30 s after three 360 J discharges 68 3 mV 53 8 mV 88 7 mV DC offset voltage at 45 s after three 360 J discharges 58 9 mV 41 3 mV 85 8 mV DC offset voltage at 60 s after three 360 J discharges 52 2 mV 31 1 mV 83 3 m
3. 2004 Description DESCRIPTION General The Welch Allyn AED 20 formerly the MRL LifeQuest AED is a lightweight compact defibrillator with a monochrome LCD screen that displays the patient data and optionally the ECG waveform There are three main versions available and a range of setup configurations thus it is designed for a wide range of personnel trained in Basic Life Support BLS i e from first responders to personnel trained in Advanced Life Support ALS The basic model is semi automatic where the user follows a three step protocol with voice and screen prompts No ECG trace is displayed The intermediate model displays ECG and provides a re useable ECG lead set to enable continuous monitoring of patients without connecting the defibrillator pads The most advanced model additionally provides full manual control of the defibrillator This facility can be made accessible only by entering a pass code Time stamped data logging facilities including audio recording if reguired are provided The data is stored internally with additional capacity on interchangeable PCMCIA memory cards Note these cards are computer readable The AED 20 in its basic form delivers biphasic shocks although the unit can be purchased with a conventional monophasic output An MHRA device alert on biphasic shock levels all manufacturers is included in the appendix Defibrillation in semi automatic mode This is a three stage process
4. 8109 or e mail AlC mbhra gsi gov uk An answerphone service operates outside normal office hours Medical Device Alerts are available in full text on the MHRA website http Avww mhra gov uk MHRA is an Executive Agency of the Department of Health Crown Copyright 2003 Addressees may take copies for distribution within their own organisations Page 2 of 3 pages 17 MHRA evaluation 04018 March 2004 Appendix Welch Allyn AED 20 ANNEX Ref MDA 2003 012 Issued 17 April 2003 Background There are many different models of biphasic defibrillator with a range of energy level protocols available on the UK market The rapid uptake in biphasic technology and the differences between energy level protocols between biphasic and the more traditional monophasic devices has caused confusion Representatives from a range of professional organisations met to discuss this matter and have issued the following joint statement A joint statement from e The Association of Anaesthetists The British Association for Accident amp Emergency Medicine The British Cardiac Society The Committee for the Safety of Devices The Department of Health s Medicines and Healthcare products Regulatory Agency MHRA The Resuscitation Council UK The Royal College of Anaesthetists The Royal College of Nursing The Royal College of Surgeons of Edinburgh Faculty of Pre hospital Care Electrical defibrillation is the only possible treatment for ventricular fi
5. and Healthcare products Regulatory Agency MHRA previously MDA Details about how to report are available on the MHRA website at www mhra gov uk or can be obtained by telephoning the MHRA Adverse Incident Centre on 020 7972 8080 MHRA evaluation 04018 March 2004 18 Welch Allyn AED 20 Appendix 19 MHRA evaluation 04018 March 2004 Appendix Welch Allyn AED 20 MEDICINES AND HEALTHCARE PRODUCTS REGULATORY AGENCY MHRA The Medical Devices Agency has merged with the Medicines Control Agency to form the Medicines and Healthcare products Regulatory Agency ACKNOWLEDGMENTS This report was prepared by Mr J A Menes Mr D R Bousfield and Mr C A Reay of the Regional Medical Physics Department Freeman Hospital Newcastle upon Tyne Enquiries to Mr Julian Menes Evaluation Centre Manager Regional Medical Physics Dept Freeman Hospital Freeman Road Newcastle upon Tyne NE77DN Tel 01912137787 Email julian menes nuth northy nhs uk Or Dr Stephen Harbron MHRA Hannibal House Elephant and Castle London SE1 6TQ Tel 020 7972 8151 Thanks to NHS staff in the following locations Stobhill Hospital Glasgow University Hospital Hartlepool University Hospital Lewisham Bedford Hospital Princess Royal University Hospital Orpington Tees East and North Yorkshire Ambulance Service Thanks to Response Medical Equipment Ltd for loaning the AED 20 defibrillators for the period of the evaluation DISTRIBUTION A amp E ambulance office
6. and technicians Accident amp emergency departments Allwards Health amp safety officers Theatre managers Risk managers Clinical govemance lead CONTACTS Enquiries to the MHRA should quote reference number S ZT 001 001 092 and be addressed to General medical practitioners General dental practitioners Lead nurses Directors of public health Clinical govemance lead Community hospitals Practice nurses Technical aspects Clinical aspects Philip Grohmann Dr Jon Hopper Medicines amp Healthcare products Regulatory Agency Medicines amp Healthcare products Regulatory Agency Hannibal House Hannibal House Elephant and Castle Elephant and Castle London SE1 6TQ London SE1 6TO Tel 0207972 8040 Tel 020 7972 8126 Fax 0207972 8115 Fax 020 7972 8103 Email Philip Grohmann mhra gsi gov uk Email Jon Hopper mhra gsi gov uk HOW TO REPORT ADVERSE INCIDENTS Incidents relating to medical devices must be reported to the Medicines and Healthcare products Regulatory Agency MHRA as soon as possible Further information about reporting incidents on line incident reporting facilities and downloadable report forms is available from MHRA s website http Avww mhra gov uk Alternatively further information and printed incident report forms are available from MHRA Adverse Incident Centre Medicines and Healthcare products Regulatory Agency Hannibal House Elephant and Castle London SE1 6TO Telephone 020 7972 8080 or Fax 020 7972
7. caused by movement artefacts Each waveform is presented three times to the defibrillator under test MANUFACTURER S COMMENTS The report was sent to the manufacturer via the UK supplier In their reply no specific comments were made Welch Allyn AED 20 Results Table RESULTS TABLE Leakage Currents pass Performance of defibrillator delivered energy in to 50 ohm load time from switch on to 200 J ready time to completion of 200 200 360 J seguence inhibition of manual defibrillation susceptibility to abnormal operations susceptibility to interference Performance of shock advisory system sensitivity to VF sensitivity to VF VT gt 150 bpm sensitivity to VF VT gt 180 bpm specificity VF VT gt 150 bpm shockable specificity VF VT gt 180 bpm shockable time to reach true positive time to reach true negative minimum amplitude shockable VF ECG leads and patient connection lead colour code lead format amp _ connection to defibrillator Monitor performance saturation level recovery from saturation sensitivity discernible on display sensitivity error display speed error baseline drift dynamic range linearity frequency response spec 0 5 to 40 Hz low frequency noise rejection spec 20 mm lead imbalance spec 20 mm mains frequency rejection use with pacemaker pulses pass AED mode 33 seconds manual mode 20 seconds 36 seconds 69 seconds pass code
8. energy level selection and charge function figure 6 Once the unit had charged the shock was delivered via the large red button Using a fully charged battery a typical time from power up to having 200J ready to discharge was approximately 20 seconds This period included the power up self test and the time reguired by an experienced user to put the device into manual mode with the passcode set to 000 Similarly the time from power up to completion of a 200 200 360 J discharge sequence was approximately 36 seconds Entering the passcode required multiple key presses to increment through each of three digits and could add a few seconds to the process Mis keying i e overshooting a digit added significant delay as there was no decrement facility There was no facility to disable the requirement to Technical Assessment 00 12 53 HR 180 Shocks 0 Figure 6 enter a passcode in appropriate clinical settings thus preventing or delaying a user unfamiliar with the AED 20 from carrying out an immediate defibrillation EMS Mode Unlike manual mode if EMS mode was activated via the passcode protected supervisor menu it remained selected at next power on Thus any AED 20 defibrillator set up in EMS mode will not work as expected by a first responder trained in BLS Even someone trained in ALS who had never seen the equipment before could well hesitate before spotting that it was necessary to press a soft key to initia
9. keys below the screen These are not marked or highlighted in any way but have a raised surface and are adjacent to indents on the screen bezel to help locate them by touch The soft keys are shown on figure 2 They are used in conjunction with labels displayed on the screen menu bar and a menu selection area on the centre left The screen itself is 14 1 cm diagonal monochrome divided into several areas or windows as shown in figure 1 The patient s ECG is displayed in the upper area above the prompts window in which text messages show defibrillator status or guide users through a defibrillation procedure Other relevant information is also displayed the patient s heart 00 12 53 HR 180 Shocks 0 MONITORING ECG PRESS TO ANALYZE i e ee Lo sees __ Figure 2 Welch Allyn AED20 rate the energy level of the most recently delivered shock and the number of shocks administered since powering up the device Operating status information is provided by displayed icons that act as pictorial indicators of battery level remaining memory used for data logging speaker volume screen contrast etc Manual mode Option When switched on the unit defaults to automated mode but is changed by pressing the manual soft key and entering a numerical pass code In manual mode rhythm analysis and voice prompts are not available The user is free to adjust the charging level over the range 2 360 J and char
10. that use monophasic waveforms There is therefore the possibility for confusion ACTION BY All healthcare professionals using extemal defibrillators ACTION All users of defibrillators should be made aware of the following joint statement made by MHRA and relevant professional organisations see Annex DISTRIBUTED to NHS Trusts England Chief Executives National Care Standards Commission Headquarters Primary Care Trusts England Chief Executives CONTACTS Details of MHRA contacts for technical and clinical aspects FEEDBACK REQUIREMENTS None required Further information supplied in the following pages The full text of this notice is on our website http www mhra gov uk Page 1 of 3 pages MHRA evaluation 04018 March 2004 16 Welch Allyn AED 20 Appendix M H RA Medical Device ALERT Issued 17 April 2003 Ref MDA 2003 012 DISTRIBUTION Please bring this notice to the attention of all who need to Know or be aware of it This will include distribution by TRUSTS to NATIONAL CARE STANDARDS COMMISSION to Liaison officers for onward distribution e Headquarters for onward distribution Directors of anaesthetics e Hospitals in the independent sector Medical directors Nursing executive directors PRIMARY CARE TRUSTS to Coronary care units e Liaison officers for onward distribution Resuscitation training officers Adult amp paediatric intensive care units Ambulance paramedics
11. 2 lead ECG NIBP EtCO gt Claimed performance characteristics output pulse characteristics charging time to 360J biphasic charging time to 360J monophasic deliverable energy manual battery capacity number of discharges Welch Allyn Inc USA 1995 semi automatic model for basic life support 2495 includes manual operation 2595 includes routine ECG monitoring 98 x 238 x 244 mm 2 4 kg 2 8 kg including battery yes removable battery forms handle rechargeable 12V 2 1Ah NiMH battery non rechargeable 12 V 5 2 Ah Lithium battery 10 year shelf life 5 year storage 5 year standby external 12 V auxiliary supply external mains powered quick charger conditioner system ready indicator on screen fuel gauge yes to printer or computer yes no yes no yes internal 1 MB memory 100 4s ECG samples or 300 time stamped events optional PCMCIA card 4MB 90 min continuous ECG or 40 min ECG amp audio 8 MB 3 hrs ECG or 80 min ECG amp audio 16 MB 6 hrs ECG or 2 5 hrs ECG amp audio yes displays attach pads message with voice prompt and alarm no no no no no biphasic truncated exponential optionally an AAMI monophasic truncated exponential characteristic available lt 8 seconds lt 8 seconds 2 5 7 10 20 30 50 70 100 150 200 300 360 J energy J NiMH Lithium 360 80 200 200 120 285 100 150 350 Continued overleaf 13 MHRA evaluation 04018 Marc
12. 4 Technical Assessment and wide complex ventricular tachycardia VT at a rate greater than 160 bpm Non shockable rhythms were various sinus rhythms including supraventricular tachycardia atrial fibrillation atrial flutter sinus rhythm with PVC s asystole pacemaker rhythms and ventricular tachycardia at a rate less than 160 bpm and or narrow complexes The unit was tested against the MHRA ECG arrhythmia database The results for sensitivity to VF and VT were good with sensitivity to VF better than 98 and sensitivity to VF and VT greater than 180 bpm better than 90 The average analysis time to reach a true positive was approximately 15 seconds The specificity was also good with results better than 88 the average time to reach a no shock decision for a true negative was approximately 19 seconds refer to the Results Table The time from power up initiation to the delivery of a 200 J shock on presentation of a definitive shockable rhythm was approximately 33 seconds The time from power up to completion of a three shock sequence 200 200 360 J was similarly measured at approximately 69 seconds The minimum amplitude of VF which the defibrillator would interpret as a shockable rhythm was determined by applying a 5 Hz sinusoidal wave the resulting amplitude was 0 094 mV Serviceability and manuals Since there was wide use of surface mount technology SMT circuit boards the service policy was for replacement of faulty
13. AED20 E FLASHING batt or serv READY DO NOT USE Figure 5 System ready indicator conditions There is a separate LCD system ready indicator located on the lower left corner of the AED 20 Without having to switch the unit on it shows whether or not the battery and defibrillator are fit for immediate use The indicator has three states see figure 5 ready the battery is properly installed and the unit is ready for use do not use the battery may not be properly installed the charge is too low or the unit requires attention flashing the battery is low and requires changing or the unit requires servicing Data logging The AED 20 stores event information including patient status ECG traces audio if enabled and treatment summary in an internal log or on an optional removable PCMCIA memory card The 1 MB of internal memory stores 100 4 second ECG samples or 300 time stamped events The 4 8 and 16MB memory cards store respectively 90 min of ECG or 40 min of ECG with audio 3 hours of ECG or 80 min ECG with audio and 6 hours ECG or 2 5 hours ECG with audio Stored information can be transferred to a printer or computer for subsequent review using SmartLink Direct software via the built in serial data port and an appropriate cable or Welch Allyn communication kit Alternatively data recorded to a PCMCIA flash memory card can be reviewed and printed using a card reader and optional SmartView
14. CG resumes as before confirmed by the screen prompt of figure 2 Description 1253 HR 180 CHECK PATIENT PRESS TO ANALYZE Figure 3 Electrode monitoring This optional facility is provided to allow extended monitoring of patients who are not in immediate need of defibrillation and so don t yet have defibrillator pads applied The two electrode ECG monitoring cable provided with this option is connected to the same socket as used for the defibrillator pads Its presence is recognised and the unit can now be used for monitoring only during which shock delivery is inhibited Rhythm analysis can be initiated by the user from a soft key if in AED mode and if a shockable rhythm is detected a voice and text prompt announces Change to pads before a shock can be given Supervisor menu A passcode protected supervisor menu allows fundamental configuration changes such as EMS mode enable disable altering the charge protocol accessing memory card facilities audio recording enable disable performing software upgrades and selecting an alternative language figure 4 Defibrillation electrodes Shocks are delivered via single use hands free electrodes there being no paddle option available Shocks 0 00 00 00 MHRA evaluation 04018 March 2004 Description for the AED 20 Both pads are of the same hexagonal shape and are not labelled as sternum and apex although they have white and blue
15. March 2004 t Zz a ines and Healthcare prod ulatory Agency rJ oq e MHRA 04018 Defibrillator Welch Allyn AED 20 DH Department of Health EVALUATION best choice e best practice www mhra gov uk nww medical devices nhs uk CONTENTS Description User Assessment Technical Evaluation Manufacturer s Comments Results Table Product Data Appendix amp MHRA alert on biphasic shock levels all manufacturers 16 SUMMARY Advantages lightweight compact good data logging capabilities generally easy to use good instructions manual Disadvantages reliability of rechargeable batteries not as good as non rechargeable lithium batteries Overall basic model is a good first responder defibrillator Fully featured model is versatile Training required before use Well liked by surveyed users BRIEF DESCRIPTION The Welch Allyn AED 20 is a lightweight semi automatic defibrillator In its various versions it is suitable for use both by first responders and users trained in Advanced Life Suport ALS The most advanced version allows manual operation in which analysis of the ECG and shock delivery is left entirely to the user The output shock has a biphasic waveform although the unit can be purchased with a conventional monophasic output if required The AED 20 has a large monochrome LCD panel with optional backlight This displays information such as user prompts shock counter battery statu
16. Switching on the defibrillator via a large green button stage 1 invokes a short self test followed by a voice prompt Apply pads to patient s bare chest attach defib pads to cable When this is done it prompts stage 2 Analysing heart rhythm do not touch the patient Screen messages are simultaneously displayed in the prompts window see screen layout in figure 1 After a few seconds of analysis if a shockable rhythm is detected the defibrillator announces that a shock is advised and to Stand clear while it charges to the configured energy level and simultaneously emits a staccato warning tone When ready a large red button lights up stage 3 with prompts to deliver the shock Press the red button now Once the shock is delivered and announced analysis of the heart rhythm recommences MHRA evaluation 04018 March 2004 Welch Allyn AED 20 Elapsed time Heart rate Shocks counter ECG trace window Menu Energy selection bar window Prompts window Icons window Defib window Menu bar Figure 1 Screen Layout Prompts are issued to check the pulse airways and carry out CPR if necessary If the shock is unsuccessful the process repeats to provide a total of three shocks at charge levels determined by the pre set though adjustable charge protocol Controls and display As well as the on off and shock controls there are four soft
17. V Construction mechanical construction satisfactory electrical construction satisfactory serviceability satisfactory Reliability faults on arrival breakdowns in service Accompanying documentation user information good service information satisfactory Notes Pass if output 15 or 3 J On presentation of a definite shockable VF rhythm Defibrillator is subjected to random sequences of control operations and multiple keystrokes in an attempt induce abnormal behaviour Measured at 5 minute intervals over a 1 hour period from switch on 5 mV rectangular pulses of 10 ms duration applied at a rate of 60 90 and 120 bpm Theoretical worst case is the maximum temperature during charging added to the temperature reached after 15 maximum energy shocks Scale used excellent good satisfactory poor unacceptable Pads stored at constant respective temperatures for one week MHRA evaluation 04018 March 2004 12 Welch Allyn AED 20 PRODUCT DATA PRODUCT DATA Manufacturer Country of origin List Price ex VAT Physical Data dimensions H x W x D weight carrying handle Power supply source type battery charger battery condition indicator Facilities ECG recorder plug in defibrillator cable internal paddles self adhesive defibrillation electrodes synchronisation shock advisory system data handling patient contact indication external pacemaker pulse oximetry 1
18. brillation the arrhythmia responsible for the great majority of cardiac arrests The success of defibrillation depends crucially on the time between the onset of the arrhythmia and the administration of the shock Recent developments in defibrillator technology have led to the introduction of defibrillators that use biphasic waveforms The majority of modern defibrillators including Automated External Defibrillators AEDs use this technology Biphasic waveforms have proved to be successful in achieving defibrillation at considerably lower energy levels than monophasic waveforms potentially reducing the freguency of adverse effects on the myocardium However the 200J 200J 360J seguence of shocks recommended for monophasic machines is not appropriate for biphasic devices Some AEDs deliver biphasic shocks at a fixed output with successive shocks at the same energy level Other AEDs employ escalating levels with successive shocks but these may be considerably lower than the conventional 200J 200J 360J sequence Thus where biphasic waveforms are employed whether by a manual defibrillator or an AED semi automatic defibrillator used in manual mode it is not usually possible or appropriate for users to deliver 200J or 360J shocks Many hospitals ambulance services and other healthcare organisations have available both monophasic and biphasic waveform machines Confusion has occurred particularly when both types are available in the same clinica
19. components to assembly level rather than repair to component level Replacement of assemblies would not be a trivial task due to the guantity of sealing compound used on several of the circuit boards However the service manual contained all the necessary information to do this as well as a good troubleshooting guide dismantling instructions and performance test procedures It was supplied simply as a printed PDF nevertheless the use of illustrations was excellent and overall it was guite satisfactory The user manual was good It too had excellent diagrams and was produced to a satisfactory guality Nearly all of the expected information was present but some was missing because the manual supplied with the eguipment was for an earlier release of the AED 20 All of the information was included in the current version Reliability The defibrillator operated without fault during the evaluation periods MHRA evaluation 04018 March 2004 Welch Allyn AED 20 The MHRA ECG arrhythmia database The database consists of 258 ECG arrhythmia waveforms that were extracted from real patients ECG recordings They were analysed by a group of cardiologists who classified them according to whether or not a patient exhibiting such a waveform should be administered a shock The majority of the shockable recordings comprise ventricular fibrillation or ventricular tachycardia The others are a mixture of other arrhythmias including a number
20. ctorily met the criterion of correctly displaying 5 ms pulses at different repetition rates Similarly a linearity test showed that the size or shape of a complex was unaffected by its position on the screen MHRA evaluation 04018 March 2004 Welch Allyn AED 20 Mains frequency noise rejection was good there being no trace deflection from a 20 Vrms 50 Hz common mode input Common mode rejection in balanced and unbalanced conditions also met specification as did low frequency noise rejection 0 5 25 Hz Pacing pulses of 5 mV and 1 ms duration were applied at a rate of 100 per minute to the ECG electrodes Such pacing pulses should be ignored by a heart rate meter in this case however they were counted as if they were ECG complexes Adjustment of the ECG sensitivity to give an adequate sized trace was automatic and its current setting was shown at the top left of the ECG trace area There were four settings of x 0 25 x 0 5 x 1 and x 2 which corresponded to measured sensitivities of 2 5 5 10 and 20 mm mV respectively this information was not in the published specification The irace speed had undoubtedly been chosen 22 5 mm s to give a five second display we measured no discernible error In AED mode a detached electrode led immediately to a three tone alarm and an ATTACH PADS message The voice prompt stated Apply pads to patient s bare chest connect defib pads to cable Alarms and voice prompts continue
21. d every 15 seconds thereafter In manual mode there was a similar response but without the voice prompt Test facilities A self test occurred each time the unit was switched on Whilst underway various messages were displayed SELF TEST INITIATED SELF TEST ACTIVE and SELF TEST PASSED FAILED Tests comprised of checks on the control buttons battery main processor internal circuitry defibrillator ECG tracing manual mode and external memory card depending on the options present and the unit s configuration The user manual contained information and checklists for staff to perform daily weekly and monthly checks Two checklists were provided one for freguent use rechargeable battery and one for infrequent use non rechargeable battery Batteries Using a set of thermocouples the temperatures achieved by a fully charged NiMH battery were logged while a series of 360J shocks were made into a 50 ohm load at a rate of three shocks in 90 seconds with a 60 second rest between groups of three shocks After 15 shocks the temperature rose by 4 6 C The test concluded when no further discharges could be Welch Allyn AED20 Battery testing The following is a summary of the manufacturer s battery capacity test When users carry out this procedure it also helps them to estimate the operating time remaining by observation of the battery icon It was important for users to check batteries monthly to determine their capacity for mon
22. es imply less Nearly all users had either extensive or moderate experience with defibrillator eguipment the majority having used the AED 20 for 2 3 years One was a trainee who answered fewer of the guestions this is why the maximum response above is 19 and not 20 Twelve had used the defibrillator in an emergency From the consistently favourable responses to all of our performance related guestions it was clear that all the surveyed users thought the AED 20 was satisfactory or beiter for use in their departments The most commonly stated opinions were either good or excellent our conclusion is that the defibrillator worked well and users had relatively minor concerns with performance When the eguipment was originally installed no serious initial difficulties occurred beyond what would be considered normal with new eguipment Data Storage One of the users a resuscitation officer said that having initially tried a 4 MB memory card to store patient data this size proved to be too small The card was upgraded to 16 MB and this size was found satisfactory MHRA evaluation 04018 March 2004 Technical Assessment Batteries All but one of the surveyed locations used the non rechargeable lithium batteries The hospital location that used rechargeable batteries had experienced difficulty with them Ward staff said that the batteries would lose their charge with the passage of time and that it could be difficult visually gau
23. ge or disarm the defibrillator as he she sees fit The shock is delivered as before by means of the red button Once the defibrillator has been switched off it reverts to AED mode at next use EMS mode This mode is provided on all models and is designed for use by Emergency Medical Services e g ambulance paramedic staff This is most suitable when continuous AED mode analysis is reguired while transporting a patient or carrying out some other procedure Its status is enabled disabled from the menu soft key the exact procedure is model dependent and requires a passcode to do so The defibrillator s EMS status remains unchanged at next use At switch on the unit behaves as in automatic mode i e the self check followed by voice screen prompts to attach electrodes Full heart rhythm analysis does not take place at this stage the screen prompt figure 2 is Monitoring ECG press to analyse but without a voice prompt voice off mode Background analysis continues to take place and if a shockable arrhythmia is detected the unit returns to voice on mode with Check Patient and a screen prompt shown in figure 3 Once analyze has been pressed the unit proceeds through analysis charging and shock assuming one was deemed necessary advice to check the patient etc in the same way as semi automatic mode If the patient is successfully defibrillated no further voice prompts occur and background monitoring of E
24. ging the remaining charge A fault that affected four of their AED 20s may have contributed to the difficulty see reliability below Their solution was to switch to using the non rechargeable batteries which have a guaranteed shelf life and capacity One user said we now use lithium batteries which are excellent Display Nearly all of the surveyed users thought that the screen size and visibility was at least satisfactory 70 said either good or excellent However one user thought that the screen could be bigger and another rated it as poor but gave no reason Electrode Pads The design and connection of the electrode pads were also generally liked However one user said that they had experienced problems when trying to attach pads to a small and frail patient and added that the connections didn t always appear secure Portability Users rated the defibrillator s overall portability very highly with the majority giving it a score of excellent Reliability Most of the users 81 had no reliability issues to report however one location that used rechargeable batteries had experienced four battery connection failures and one on screen battery indicator failure see Batteries above They said that the repairs took a long time although loan units were supplied An ambulance service user said that he thought the machine was unreliable as it had failed to shock under emergency conditions although th
25. h 2004 Product Data Welch Allyn AED 20 Claimed performance characteristics continued AED shockable rhythms AED analysis time AED output energy Joules Controls and indicators discharge controls built in defibrillator tester indication of deliverable energy e disarm ECG monitor patient monitoring cable lead selector sensitivity settings sensitivity indication heart rate alarms display size H x W display type trace freeze trace speed event marker Communications internal or external modem other Accessories amp standard optional MHRA evaluation 04018 March 2004 VF gt 150 uV and wide complex VT gt 160 bpm 12 16 seconds user configurable biphasic 150 200 300 manufacturer s default setting first shock settings 150 or 200 second shock settings 150 200 or 300 third shock settings 150 200 300 or 360 monophasic models 200 200 360 or 200 300 360 see MHRA alert in appendix on biphasic shock levels single flashing red triangular button on front panel yes self test runs at switch on yes on screen energy bar in auto amp manual mode automatic disarm after 30 s in auto mode with warning tone after 25s and 60s in manual mode disarm button in manual mode only yes single channel 2 wire no only fixed lead II RA LL automatic sensitivity control on screen x 0 25 x 0 5 x 1 x 2 also shown on log print out no 87 x 114 mm
26. he pins looked a little less durable After many years use it could be susceptible to wear and subsequently reduce the reliability of connection with the pads electrodes Fortunately the adapter socket was replaceable thus with effective servicing there should be no problem The adapter also obscured the Type BF symbol engraved adjacent to the input required by EN 60601 1 but this has been corrected on recent models The DC offset voltage produced across the pads following three maximum energy 360J discharges was measured at 5 10 30 45 and 60 seconds following the last discharge The voltage dropped from 91 1mV at 5 seconds to 52 2mV after 60 seconds This was well within the capabilities of the monitor see page 7 The pad impedance was measured every five discharges over a 30 discharge period maximum energy 360 J shocks were delivered at 30 second intervals into a 50 ohm load At room temperature the pad impedance measured approximately 0 25 ohm rising to 0 28 ohm after the 30th shock Unopened packets of pads were conditioned according to the MHRA test protocol at a constant 2 C and 40 C respectively for one week in a temperature controlled environment No change in physical appearance or performance resulted Rhythm analysis The ECG rhythm analysis algorithm was designed to recognise as shockable any ventricular fibrillation VF waveforms with amplitudes greater than 150 uV MHRA evaluation 04018 March 200
27. is had apparently been due to a poor pad contact pads too large for small frail patient see electrode pad comments above We asked users if they were responsible for the decision to purchase the device and if so why they chose the AED 20 Several users commented with answers such as easy to use and portable with a limited amount of preparation needed price was competitive the unit appeared robust and came with a 7 year warranty and I wasn t responsible this time but in the future I would be very happy to purchase for both community and hospital based use Training The manufacturer had given training to eleven of the twenty surveyed users the MHRA evaluation 04018 March 2004 Welch Allyn AED 20 remainder had undergone formal training by their employer Only one of the users was dissatisfied with the manufacturers training he said that he thought it was very basic General To summarise the majority of our user sample were very happy with the AED 20 Typical comments were An excellent easy to use defibrillator with a comprehensive recognition algorithm and excellent self adhesive electrodes Very portable and easy to use I especially like the audible messages A satisfactory unit that is reasonably simple to use with clear display and functions TECHNICAL EVALUATION Our main findings are discussed in this section A summary with numerical and other data is given in the Results Table The evalua
28. itoring 1 Connect a patient simulator or test load to the defibrillator without either the unit would auto shutdown after 10 minutes note the start time 2 Verify operation every 30 minutes or less 3 Note when the battery runs out the overall time gives an indication of its capacity typically it should provide at least 3 hours of monitoring 4 If operating time is less than 3 hours recharge the battery and repeat the test if the operating time remains at less than 3 hours remove the battery from service 5 Recharge batteries fully before returning to use Those charged in high ambient temperatures gt 30 C or which normally encounter more than one daily charge discharge cycle to be reconditioned once every 30 days Users were warned not to exceed the stated battery life of 24 months made and the defibrillator shut down The maximum temperature achieved was 41 5 C a rise of 16 8 C above ambient After the 56th shock alarm tones were sounded the on screen battery gauge displayed low and the system ready indicator began to flash In total 75 shocks of 360 J were delivered At this stage with the defibrillator now incapable of further operation it shut down to prevent deep discharge of the battery The system ready indicator continued to flash thus showing that the battery needed replacing A theoretical worst case scenario is when a battery is removed from the charger at the point of maximum charging te
29. ivating semi Welch Allyn AED20 Using defibrillators what are we assessing AED manual defibrillators should ideally Be simple to use by first responders with no risk of confusion by controls intended for manual operation Be straightforward to use for emergency defibrillation in manual mode by medical staff not already familiar with the device As well as assessing the above we check to see if any mode of operation can inhibit emergency defibrillation or if the software is susceptible to malfunction caused by random and multiple use of controls We also check how long it takes to deliver 200 J from power up automatic operation From the soft keys simple functions e g speaker volume were directly available and also access to the user menu functions see left hand section figure 4 The soft keys were much less prominent than the on off shock buttons so as not to provide a distraction to first responders Manual operation The AED 20 was primarily a semi automatic device and manual use requires that option to be installed Since at power on the unit defaulted to semi automatic mode it was first necessary to operate the manual mode soft key This key was available as soon as the self test began so could be selected almost immediately if the passcode was set at 000 and known to be so Once self test was complete the unit switched to manual mode within which its default soft key menu provided immediate access to
30. l area It is essential that healthcare professionals who might use a defibrillator whether in emergency or elective clinical circumstances are fully educated and trained to use the equipment available to them They should understand that energy levels might differ among different defibrillators and be confident that they can perform defibrillation without delay using the equipment that is available to them They should also be aware that the energy levels delivered by AEDs used in automatic mode whether monophasic or biphasic are programmed in advance and do not require adjustment or any other input from the operator when used in a resuscitation attempt The Controls Assurance Standard for Medical Devices Management requires NHS organisations to ensure that all professional users are trained in the safe operation of medical devices The dual approach of device rationalisation for instance ensuring that any one clinical area or directorate has identical equipment and regular staff training should be used to eliminate the risk of confusion about different energy levels employed by different biphasic defibrillators and how these energy levels differ from those recommended for monophasic defibrillators As with all medical devices and equipment if users of a device are concerned that it has not functioned correctly or that there are inadequate instructions for use supplied by the device manufacturer this should be reported to the Medicines
31. leads respectively To ensure correct placement they are imprinted with diagrams showing their ideal positions The pad set s twin leads 1 m long are terminated with a plastic non reversible connector that plugs into the defibrillator via a small moulded adapter The connector is held in place by a built in latch Power supply options The AED 20 is powered by a 12 V battery which slots into the defibrillator case where it locks into position and forms the device s carrying handle There are two battery types a rechargeable 12 V with a capacity of 2 1 Ah or a non rechargeable 5 2 Ah lithium battery that has a claimed standby life of five years while installed in the defibrillator following a claimed storage life of up to five years i e 10 years in total The NiMH batteries are charged using a separate unit see below taking 1 5 to 2 hours to complete The charger also conditions batteries to maintain them in their optimal state for as long as possible The manufacturer recommends renewal of NiMH batteries every 2 years A new NiMH battery is specified to provide three hours continuous monitoring from a single charge or 80 shocks at 360 J a new lithium battery is specified for 6 hours or 200 shocks An on screen battery fuel gauge shows the remaining power and whether the battery is rechargeable or non rechargeable Ich EEE NiMH battery in charging unit MHRA evaluation 04018 March 2004 Welch Allyn
32. mperature inserted into the defibrillator and discharged by delivering 15 maximum energy shocks However the calculated temperature for these batteries was only 39 4 C A fully depleted battery was again monitored for temperature during the charging process After 79 minutes the maximum temperature achieved was 34 8 C a rise of 10 8 C above ambient We also tested the non rechargeable lithium battery we found that it was capable of delivering 201 shocks of 360J into the 50 ohm load reaching Technical Assessment a maximum temperature of 42 4 a rise of 19 6 C above ambient Low battery alarms and messages occurred after the 188th shock Defibrillation pads The supplied pads were Cardiotronics Systems R2 model 3200 01 adult radiolucent multifunction conductive adhesive electrodes They were manufactured by Ballard Medical Products and packaged as Kimberly Clark R2 model 3200 1715 The packaging had clear application instructions CE marking and diagrams showing acceptable pad positioning The expiry date was clear and the storage temperature range was shown 5 to 35 C The pad connector plugged directly into a right angled adapter socket on the front of the defibrillator However the plug had to be oriented correctly to plug into the socket and there was no visual aid to help the user do this quickly e g colour coding the adapter to match the plug The body of the adapter seemed robust but the plastic lining around t
33. nder long term contract to and in accordance with protocols approved by the MHRA The evaluations are usually of a unit supplied by a manufacturer We would expect this unit to be representative of the product on the market but cannot guarantee this Prospective purchasers should satisfy themselves with respect to any modifications that might be made to the product type after MHRA s evaluation The reports are intended to supplement not replace information already available to prospective purchasers CROWN COPYRIGHT 2004 Apart from any fair dealing for the purpose of research or private study or criticism or review as permitted under the Copyright Designs amp Patents Act 1988 this publication may only be reproduced stored or transmitted in any form or by any means with the prior permission in writing of the Controller of Her Majesty s Stationery Office HMSO Enguiries about reproduction should be made to the MHRA at the above address MHRA evaluation 04018 March 2004 20 ISBN NUMBER 1 84182 835 1
34. rs anaesthetists cardiac and coronary care cardiology dental ECG departments EBME Health Service Authorities hospital authority libraries intensive care therapy maternity midwifery medical physics nursing physiotherapy radiology renal units supplies departments surgical theatre staff general practitioners with an interest in immediate care HOW TO OBTAIN COPIES Evaluation Reports are free of charge to NHS Trusts and Clinics In England In Scotland In Wales In Northern Ireland MHRA Scottish Healthcare Supplies National Assembly for Wales Health Estates Room 1207 Trinity Park House Health Services 3 Division Stoney Road Hannibal House South Trinity Road Cathays Park Dundonald Elephant amp Castle Edinburgh EH5 3SH Cardiff CF10 3NQ Belfast BT16 0US London SE1 6TO Tel 0131 551 8350 Tel 029 2082 3087 Tel 028 9052 3714 Tel 020 7972 8181 OTHER RECENT MHRA REPORTS ON DEFIBRILLATORS Schiller FRED 392 HME LifePulse 282 Phillips Medical Systems M4735A 371 Physio Control LIFEPAK 12 series Heartstream XL 359 Defibrillators Review Issue Zoll M series 344 Physio Control LIFEPAK 500 GE Medical Systems Responder 3000 312 GE Medical Systems Cardioserv Bruker Defigard 3002 IH WHAT YOU CAN EXPECT FROM MHRA evaluation REPORTS DISCLAIMER The Device Evaluation Service DES aims to provide independent and objective evaluations of medical devices available on the UK market Specialist centres mainly in the NHS do evaluations u
35. s Summary Information Defibrillator Welch Allyn AED 20 MAIN FEATURES rechargeable NiMH or non rechargeable lithium battery Power Supply Claimed Performance Characteristics amp charging time 360 J lt 8 seconds deliverable energy 150 200 300 360 J in semi automatic mode 2 360 J manual mode discharge mode biphasic or monophasic Facilities amp ecg display optional amp _ecg recording to printer or computer 1 MB internal memory amp 4 8 or 16 MB PCMCIA shock advisory yes log review optional data handling and timer More advanced models display the ECG trace this facility is enabled or disabled from a supervisor menu that is password protected The shock protocol is also configurable from this menu The on screen instructions augment voice prompts when the unit is in AED mode Power is from either a rechargeable NiMH battery re charged externally or a non rechargeable lithium battery The battery forms the carrying handle when inserted into the defibrillator the idea being that the unit cannot be picked up and carried to an incident if it is not present Shocks are administered by single use multi function electrode pads there is no paddle option Price ex VAT from 1995 list price CE Marking MD Directive CEo197 Notified Body T V Rheinland Product Safety GmbH Manufactured to EN 60601 1 amp other relevant Standard standards MHRA evaluation 04018 March
36. software USER ASSESSMENT User opinion was obtained from a survey of existing users in six NHS locations There were 20 respondents representing nursing staff resuscitation officers ambulance service paramedics and EBME staff Users were asked to complete questionnaires grading their answers on a five point scale The principal results were averaged see graph together with a breakdown of how many users awarded each score Each average rating also has an consensus bar that helps to show the Welch Allyn AED 20 User Assessment User Survey Results Top Graph Average Rating with Consensus Bars Lower Graph Distribution of Ratings Good Poor V Poor Number of Responses o o o oo o i y a o o wn c n T o FSssss8 55 S SR GFFss es EEE SB gt 9g ES F 5 sb k amp Se 8 OE 2 S 5 9 8 5 5 9 E o 2 gt S o Q amp 3 S SsSeeg2s95825 8 8 BSESCTB o z E amp 25 ok Fez 2 6 3 eL 5 2 5 S9 6 9929 ona 9 a gt 3 o 2 F s gt o Ss 5 o Q 3 gt oO Hu a o o z2 9 zage 5 m Ww o Mu o 9 2 535 5 2 9 o gt 0 LC as Lu c q o 5 z o oO 5 mn o v wW 2 g D o ma 5 5 Very Poor E Poor E Satisfactory E Good E Excellent level of agreement among users short bars imply good consensus but long on
37. te rhythm analysis Defibrillator Performance The manufacturer stated that delivered shocks were in the form of a biphasic truncated exponential waveform The waveform of a 360 J discharge into a 50 ohm load is shown in Figure 7 the voltage peaked at 1290 V and 830 V in the positive and negative phases respectively with a total shock duration of 21 ms In manual mode delivered energy into a 50 ohm load was measured and found to be in good agreement with the energy delivered display In manual mode this message remained for approximately 10 seconds Tests were carried out to see if normal operation of the defibrillator could be upset by a combination of keystrokes or a random series of keystrokes None was found except if this activity occurred during the power on self test Since one of the self tests was to check the integrity of the controls unusual key presses at this time could not unexpectedly cause the test to fail This was announced by four warning beeps a screen message and the do not use symbol was illuminated Correct operation was restored by switching the power off and then on again MHRA evaluation 04018 March 2004 Technical Assessment 1500 Peak Voltage ve 1290 V 1000 Voltage V Energy Delivered 352 3 J Q 12 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 2 500 1000 Peak Voltage ve 830 V Time ms Figure 7 ECG monitor The cable supplied
38. ted AED 20 sample was an earlier MRL LifeQuest AED model 970200 the installed software was version V 05 07 00UK Safety The defibrillator carried CE marking in respect of the Medical Devices Directive MDD of the European Community Documentation showed it to be a class llb device manufactured by Medical Research Laboratories Inc Illinois USA a Welch Allyn owned company the assessment route was via Annex ll of the Medical Device Directive 93 42 EEC the notified body was TUV Rheinland Product Safety GmbH Germany Identification No 0197 Compliance with EN 60601 1 and other relevant standards was claimed Using the AED 20 Semi automatic operation As a semi automatic defibrillator we thought the AED 20 would be straightforward to use by trained first responders user opinion confirmed this was the case User prompts both audible and visual were clear and unambiguous requiring the user only to press the shock button after it had illuminated if a shock was deemed necessary In the case of a defibrillator with the manual option the unit defaulted to semi automatic mode at switch on i e it behaved identically to the basic AED 20 option The process was slightly less straightforward if the ECG cables were connected instead of a pad set manual and intermediate models when the unit was monitoring only Even so it was easy to initiate analysis of the patient s waveform before applying defibrillation pads thus act
39. with the ECG upgrade option was a two electrode cable which attached to the defibrillator in place of the pads via a keyed connector The two electrode snap on connectors were labelled R red right arm and F green left leg in accordance with IEC colour 1 convention to give a fixed lead ll configuration Once connected the defibrillator displayed MONITOR ONLY since it could not deliver shocks via the monitoring cable Thus if the charge key was pressed in manual mode a tone sounded with a warning CHANGE TO PADS Physiological effects caused by the application of electrodes to a patient can create DC offsets that might interfere with monitoring Thus DC offsets were applied to the electrodes until cut off of ECG monitoring occurred This was signalled by a message ATTACH PADS and warning tones when offsets of 2 48V and 2 55V had been applied ECG trace recovery from the applied offsets after their removal was less than one second a good result Over a one hour period no drift of the baseline occurred The trace position and intensity were non adjustable but there were nine discrete settings of display contrast none of which caused the trace to entirely disappear The specified frequency response was 0 5 40 Hz though given the pixel size of the LCD panel only freguencies up to 31 6 Hz were theoretically reproduceable The measured frequency response was approximately 1 25Hz The dynamic range of the display satisfa

Welch Allyn AED 20

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