Walk Free User Manual

Walk Free User Manual

INTRODUCTION

PURPOSE OF THE MANUAL

This manual refers to devices Walk Free.
The manual represents a guide for execution of the following operations:
  1. Reasonable use of the device and use of the function keys.
  2. Preparation of the device for use 
  3. Execution of a test
  4. Maintenance and troubleshooting

RECIPIENTS

This manual is intended for professional healthcare operators. They are therefore presumed to have specific knowledge of medical procedures and terminology, as required by clinical practice. It’s  responsibility of  the physician, or of the authorized personnel that prepares the patient to inform the patient about how to use the device, the operations he/she is allowed to perform and the related risks.

INTENDED USE

Walk Free is an ECG Holter recorder intended for continuous measurement and digital storage of ECG signals during the patient’s daily activities as part of a long‐term/Holter ECG. The recorded data are used to diagnose cardiac arrhythmias
The recorded data, store in the  internal memory of the device, is downloaded from Walk Free to a PC in a medical facility and evaluated with a suitable Holter‐ECG analysis software. The recorded data are transferred to the PC through a USB connection. A doctor evaluates the normal and abnormal ECG data for further therapeutic measures.
The device is indicated for use in a clinical setting: hospitals, clinics and outpatient facilities of any size. It is also suited for home use.
  1. The device is indicated for continuously recording the ECG signal. 
  2. The device is not indicated for use as physiological monitoring of vital signs.   
  3. The device must not be used on the open heart.   
  4. The device is not intended as the only means for determining the diagnosis.   
  5. The device is indicated for use on adult and pediatric patients.   
  6. The device is indicated for use by a physician or trained personnel acting on behalf of an authorised physician.

DESCRIPTION OF THE DEVICE

The Walk Free is a medical device for long‐term Holter ECG data recording with the following features: 
  1. No cables necessary. 
  2. High wearing comfort for the patient.   
  3. Low effort for cleaning and disinfection.   
  4. Easy application or removal of the adhesive electrode(s) via three pushbuttons.   
  5. Continuous recording of three ECG signals up to 9 days without changing the battery.   
  6. Recording of usual 24h – 48h Holter ECGs.   
  7. Support for event marking by the patient (e.g. in case of symptoms or medication).   
  8. Secure and simple data download via the integrated USB interface.   
  9. Bluetooth interface for patient‐specific initialisation of the device.   
  10. Support of standardized ECG data formats such as MIT, ISHNE, EDF+.  
By using decentralised single‐use electrodes in conjunction with state‐of‐the‐art hardware and software technology, Walk Free enables permanent recording of long‐term ECGs well over 24h with very high signal quality and at the same time maximum patient comfort
By eliminating previously common cables and due to the integrated intelligence, Walk Free requires almost no operation steps and thus enables (especially for ambulant applications with elderly patients) ECG recordings without affecting patients in their usual living environment and quality of life. For the first time, this enables practicable, efficient, and safe “round the clock” long‐term ECG recordings. By simply  changing the single‐use electrodes, Walk Free can be used  as  a  long‐term recorder for ECG
Advantages for the cardiologist
  1. Simplest configuration, commissioning and application
  2. Secure recordings by cable‐free technology; also over long periods of time (no loose cables, no loose adhesive electrodes, and no bad electrode contacts).
  3. Modular concept enables ECG recordings over theoretically unlimited periods of time.
  4. High signal quality by eliminating the cables and derivation of the vectors on the smallest area (low‐artefact, low‐interference ECG recordings).
  5. Low patient instruction effort for ambulant recordings.
Benefits for the patient
  1. No impairment of quality of life and habits. After a short wearing period, you don't notice the WalkFree anymore.
  2. Simplest operation/handling by patients even during longer recording periods (only necessary to change electrodes)
This device includes:
1. Recorder module (Walk Free): It includes the electronics for measuring and storing 3 ECG leads.

2. Batteries AAAA size: It is a disposable part and must be changed after each examination

3. Decentralised single-electrodes: Using three decentralised single-use ECG adhesive electrodes, the recorder module measures and calculates the leads. The electrodes are also disposable part

4. PC initialisation software (Device Web Manager) provided via a link where you can download it.
5. PC micro USB cable

6. Battery cover

7. Operating manual

GENERAL OVERVIEW

Front View
Device with electrodes
Rear View
Device without electrodes

CONTROL AND DISPLAY ELEMENTS

Control elements
The Walk Free does not include any control elements
Display elements
The Walk Free includes 3 LEDs for displaying device/battery and error status as follows:


State "Self-test"
In this state, Walk Free perform an internal self-test, during which all important functions of the device are tested


State "Ready for initialisation"
In this state, Walk Free is ready for initialisation by Device Web Manager software. This state is displayed as follows:
NOTE: This condition is automatically activated after the battery has been installed on the recorder module of the Walk Free and after self‐testing has been carried out.

State "Initialisation"
In this State, an initialisation by the Device Web Manager software takes place. This state is displayed as follow:


State "Signal Control/ECG display"
In this state, an amplitude modulated (with brightness modulated) display of the 3 ECGs via the 3 ECG LEDs of the Walk Free takes place as follows:


State "ECG recording"
In this state, an ECG measurement and recording takes place. Patient contact is available.


State "Pause"
In this state, the ECG measurement and recording is interrupted because there is no patient contact:


State "End"
This state indicates the end of a recording. This state is achieved e.g after a serious error or after a detection of an empty battery.


State "Battery State"
The battery state is displayed at Walk Free as follows:


State "Error State"
A serious error leading to the interruption of the recording is displayed at Walk Free as follows:


PREPARATION FOR USE

SWITCHING ON THE RECORDER

To switch on the recorder insert 1 AAAA type battery in the battery compartment on the front of the recorder.

Carefully close the battery compartment with the lid.

WARNING: insert the battery paying attention to positioning it correctly, as shown in the diagram stamped in the battery compartment
WARNING: remove the battery from the unit in the event of prolonged inactivity.
When a battery is inserted all 3 LEDs of the Walk Free have to light up cyclically (state self‐test). After self‐testing the Walk Free switches to the state "Ready for initialization” and waits for contact with the patient. After applying the recorder to the patient and recognizing contact to the patient, the Walk Free switches to "Initialization“ and awaits initialization of the ECG recording.

INSTALLATION OF DEVICE WEB MANAGER INITIALISATION SOFTWARE

To install the Device Web Manager software, click on the link here

EXECUTION OF THE EXAMINATION

GENERAL PROCEDURE

The operations required to perform a Holter recording are described below.
1. Prepare and connect the patient
2. Prepare and start recording.
a. initialisation and start of ECG recordings;
b. instruct the patient.
3. Definition of manual event markers.
4. Cyclical function control.
5. Stop ECG recording and analysis of ECG recording.
NOTE: Strictly adhere to instructions on preparing the patient, one of the most crucial stages for successful recording.

PREPARING THE PATIENT SKIN

Before connecting the electrodes, ensure the patient has fully understood the procedure and knows exactly what the test they are doing consists of, that they have been correctly instructed on the required behaviour throughout the recording and are ready for any actions to be taken in special cases and to perform everyday activities.
  1. Privacy is very important to allow the patient to be relaxed.
  2. Reassure the patient that the procedure is painless, and that they will only feel the electrodes on the skin.
It is important that the patient's skin be accurately cleaned. There is a natural electrical resistance on the surface of the skin, generated by various sources such as hair, sebum, and dry or dead skin. Skin preparation is required to minimise the negative effects caused by excessive skin‐electrode impedance and to optimise the ECG signal quality.
To prepare the skin:
  1. If necessary, shave the skin area where the electrode must be applied.
  2. Wash the area with hot soapy water.
  3. Dry the skin vigorously with an abrasive pad, such as a gauze, to remove dead skin cells and fat, and to increase blood flow in the capillaries.
NOTE: In patients who use Body Lotion, the skin must be cleaned or degreased particularly carefully.  
NOTE: Pay attention not to cause abrasions, discomfort or bruises on the skin of elderly or fragile patients.   

CONNECTING THE PATIENT

It is important to position the electrodes properly in order to acquire a good electrocardiographic signal. Lower impedance, in fact, provides better waveform, reducing noise, and good quality electrodes should be used for the same reason.
Apply the Walk Free recorder and connect the electrodes as follows:
Attach 3 individual electrodes to the Walk Free recorder according to the following image.

  1. Remove the protective foils on the undersides of the electrodes.
  2. Apply the Walk Free recorder to the patient by sticking the electrodes and recorders to the patient’s skin in accordance with the recommendations of positioning of the electrodes and press with medium force on the recorder and on the outer contours of the electrodes.
  3. Try to place the electrode(s) in such a way that as little curved skin surface as possible must be balanced.
  4. The use of decentralized electrodes reduces artefacts (e.g. for more corpulent patients) and can be better placed on complex skin surfaces.
  5. Make sure that all 3 contacts of the electrode and the recorder module are connected. Check this by slightly lifting the recorder module at each electrode contact. A good positioning should also prevent a “raising” of the electrodes during movements.
  6. If possible, avoid placing the electrodes directly on muscle tissue.
  7. Avoid mechanical stress on the electrodes.

SUITABLE ELECTRODE TYPES

For the use of the Walk Free Holter recorder systems it is recommended to use the following types of electrode:
  1. AMBU decentralized electrodes, type „Blue Sensor L“, “Blue Sensor VL” or “Blue Sensor VLC” (for sensitive skin), for children „Blue Sensor P“, available from the distributor of the Walk Free Holter recorder systems or from specialist retailers.
WARNING: Always note the “durability date” of the electrodes according to the technical data and the information on the packaging of the electrodes.
WARNING: In case of open packs: Use the single‐use electrodes within a maximum of 5 days (please pay attention to the manufacturer’s information).
WARNING: When choosing the electrodes, pay attention to the suitability of the electrodes for Holter and long‐ term ECG recordings, especially with regard to skin compatibility or suitability for use in children under 10 kg.

POSITIONING THE ELECTRODES

The electrodes can be positioned as follows:
Recommended position: Middle rib cage

Alternative position

NOTE: Make sure that the electrodes are not positioned too high; the lower electrode(s) should be positioned as close as possible to the horizontal heart axis.
NOTE: When placed on the left chest: Make sure that the electrodes are not positioned too far to the left, the right electrode poles should be placed as close as possible to sternum
Prepositioning without adhesive electrodes

NOTE: The positioning closer to the atrium increases the P‐wave.

INITIALISATION AND START OF ECG RECORDING

The ECG recording should be initialised and started as follows:
  1. Initialisation via Device Web Manager (with USB connection)
In order for the ECG recording to be initialised, Walk Free must be in the state "Ready for initialisation" or state “Signal control/ECG display”.
You can see the state "Ready for initialisation" by the fact that the green LED on Walk Free flashes 2 times in a row every 2 seconds. This condition is activated automatically after the Walk Free has been applied to the patient.
They recognise the state of "signal control/ECG display" by the fact that all 3 LEDs on the Walk Free flash at the rhythm of the heart rate. This state can be activated at any time by double‐clicking on the housing of the Walk Free recorder.

INITIALISATION OF DEVICE WEB MANAGER

To initialise the Walk Free using the Device Web Manager

INSTRUCTING THE PATIENT

Clinical practice requires the patient to wear or carry the device inside or outside the hospital, in indoor premises as well as outdoors.
It is therefore especially important for the patient to be sufficiently instructed about the operations he/she is allowed to perform and the related risks. 

DEFINITION OF MANUAL EVENT MARKERS

The Walk Free offers the possibility that the patient can define manual event markers at any time, for example if he feels “uncomfortable” or if he suspects arrhythmias (with appropriate symptoms). Event markers can be defined by the patient as follows:
  1. Double click/double stroke on the housing of the Walk Free.
  2. After the definition of a manual event marker, the Walk Free switches to the status “signal control/ECG  display”.
In this state an amplitude modulated (thus brightness modulated) display of the 3 ECG derivatives via the LEDs of the Walk Free takes place.  
NOTE: To make sure that a manual event marker has been detected by Walk Free, repeat the double click on the case until the state “signal control/ECG display” is displayed and all 3 LEDs (red, yellow green) on Walk Free flash at heart rhythm. 

CYCLICAL FUNCTION CONTROL

During an ECG intake, a cyclical functional check should be carried out as follows. Note the following hints:


If the Walk Free is temporarily removed from the electrode (e.g. during body cleansing or when changing the electrode), this is recognised by the Walk Free and the device changes to the State “Pause”. In this state, instead of an ECG’s a zero line or a pseudo QRS complex at 60 bpm is recorded.
After the re‐attachment of the Walk Free on the electrode (after detection of the patient contact), the device proceeds independently with the ECG signal recording and storage (state “ECG recording”).
The states “ECG recording” and “Pause" are displayed by Walk Free via the green State — LED   
The complete description of the state displays is in control and display elements.  

STOP ECG RECORDING AND ANALYSIS OF ECG RECORDING

STOP ECG RECORDING

To finish the ECG recording, simply remove the Walk Free from the electrodes and remove the battery from the recorder module

READ OUT THE ECG RECORDING/IMPORT INTO THE ANALYSIS SOFTWARE

Connect the Walk Free recorder to the computer on which the analysis software is installed via the supplied USB cable.

Then import the ECG recording from the Walk Free recorder into the analysis system used and analyze the ECG recording according to the instructions in the respective user manual of the analysis system used.

ATTENTION: Make sure that the software of the analysis system is configured correctly so that the Walk Free Recorder is recognized by the analysis system and it can work correctly with the Walk Free Recorder. Follow the instructions in the user manual of the evaluation system used. ECG recordings are only permitted to be read out if the device has no connection to the patient (via the ECG electrode contacts).

MAINTENANCE AND TROUBLESHOOTING

CLEANING AND DISINFECTION

Clean and disinfect Walk Free after each application to a patient. Ensure sufficient ventilation. Do not sterilise the device with steam, ethylene oxide, ultrasound or gamma rays.
The surface of the device must be cleaned with a damp cloth. Do not immerse the Walk Free in water and other liquids. Under no circumstances should liquid enter the recorder. Do not use abrasive cleaning agents to clean the device.
Walk Free must not be cleaned with organic solvents such as petrol, alcohols or ethers in order to avoid material fatigue, discoloration or breakage.
Cleaning 
  1. moisten a soft cloth with soap solution or aqueous alcohol solution (70 % ethanol/30 % water);
  2. clean the Walk Free.
Disinfect 
  1. Moisten a soft cloth with an aqueous alcohol solution (70 % ethanol, 30 % water) or a plastic‐suitable cleaning solution, better cleaning cloths or tissues, for sensitive medical devices.   
  2. Wipe the Walk Free. NOTE: cleaning and disinfection of the device should not be performed by the patient.

CHANGE OF ELECTRODE

The electrodes defined for the use of the Walk Free are suitable for ECG recordings over several days and have very good adhesive and contact properties. However, it is recommended to change the electrodes after 2 days at the latest, at warm and hot temperatures every 24 hours.
Proceed as follows:
  1. Remove the Walk Free /electrode from the patient’s body and separate the Walk Free from the electrodes.
  2. Clean the body surface according to the instructions on preparing the patient's skin.  
  3. Also remove any adhesive residues of the predecessor electrode.
  4. Dry the skin before applying the new electrode.
  5. Use new electrodes and first apply the electrode(s) to the Walk Free recorder according to the following images:

  1. Remove the protective foils on the undersides of the electrodes.  
  1. Then attach the Walk Free recorder with the electrodes to the patient’s skin.
  2. Press with medium force on the recorder and on the outer contours of the electrode.
NOTE:  
Do not disconnect the Walk Free from the battery while changing the electrode.  
Always glue a new electrode to the same place as the predecessor electrode.  
ATTENTION: 
Always note the “durability date” of the electrodes according to the technical data and the information on the packaging of the electrodes.
In case of open packs: Use the electrodes within a maximum of 5 days (compliance with manufacturer’s recommendation).

BATTERY CHANGE

  1. Although the Walk Free battery allows up to 9 days to record (for new or fully charged batteries), it may be necessary to change the battery for long‐term recordings.
Proceed as follows:
  1. Remove the battery cover from the recorder.
  2. Then insert a new battery into the battery compartment as follows:
    1. Note the polarity and insert the battery as shown in the picture.
    2. The three control LEDs at the top of the recorder are starting to flash.

  1. Carefully close the battery compartment with the lid.

  1. Apply the recorder module back to the electrodes after changing the battery or use new electrodes).
NOTE: 
After inserting the battery into the recorder, all 3 LED’s of the Walk Free have to light up cyclically for a few seconds (Status “Self‐test”).
After a battery change, the Walk Free continues the ECG recording on its own.
ATTENTION 
Monitor the battery status display at Walk Free regularly during an ECG recording (especially for long‐term recordings).  
Change the battery as soon as the battery status indicator shows the status “EOS‐2” (yellow LED flashes in seconds).
At the start of a recording, definitely use a new battery.

SELF-TESTING, INTERNAL SURVEILLANCE AND PROTECTION

ATTENTION:
In order to ensure the good maintenance and the safety of the device the manufacturer recommends the following tests for the operator, which he/she can also carry out himself/herself:
  1. Visual inspection: Housing damage.
  2. Functional tests: o no error indicator by red LED after booting;
  1. signal control according to instructions for use;
  2. recording of test signals, reading out data and checking signal quality for interference.
The check interval should be 36 months.

SELF-TESTING

The Walk Free has the following internal monitoring and protection measures:
  1. Self‐test after switching on
  2. Self‐test during operation
Self‐test after switching on 
After switching on (after inserting the battery), Walk Free independently carries out an extensive functional test, during which all functions of the device necessary for operation are tested. During this test, the following functions of Walk Free will be tested:
  1. Test of the internal microcontroller (RAM, Flash, Timer and Function).
  2. Test of internal supply voltages.
  3. ECG amplifier test (configuration and function test).
  4. ECG memory test (read/write test, size and free memory).
  5. Battery inserted test (capacity check).
  6. Test of the USB and Bluetooth interface (write/read test).
Self‐test during operation 
During operation, Walk Free additionally checks the following functions cyclically:
  1. Test of internal supply voltages.
  2. ECG memory test (read/write test, size and free memory).
  3. Test of the connected battery (capacity check).
NOTE: If a result of a self‐test is negative, the ECG recording is not started and the Walk Free goes into the “error” state. This condition is displayed via the permanently activated red LED for a duration of approx. 1h. Then the Walk Free switches itself “OFF”.

INTERNAL MONITORING AND SAFEGUARDS MEASURES

The Walk Free includes the following internal protective measures:
  1. Defibrillation resistance according to AS3551:2012 (recovery time ≤ 5 s).
  2. Stress resistance/test voltages to applied part according to AS3551:2012.
  3. Leakage currents to the applied part according to AS3551:2012.

ELECTRODES MONITORING

The Walk Free checks the electrode/skin contact cyclically during the ECG recording as follows:
  1. If an electrode impedance limit is exceeded, a zero line or a pseudo QRS complex with a frequency of 60 bpm shall be recorded for the duration of exceeding this limit.  
  2. If the limit value is lower, the ECG recording will be continued again. 

CYCLICAL FUNCTION CONTROL BY THE USER

Walk Free supports functional control by the user (doctor or patient). The function control can be performed by the user in the following ways:
  1. by checking the status indications;
  2. by activating the signal control.

TROUBLESHOOTING TABLE

Although Walk Free has extensive self‐testing and monitoring functions, dysfunctions can occur occasionally. Please note the following information:
Problem
Cause
Solution
No LED lights up after inserting the battery. 
  1. Battery failure (empty battery)
  2. Error recorder module
  3. Battery inserted wrongly
  1. Remove the battery and insert it again.
  2. Insert the battery with a plus pole in the housing recess of the battery compartment.
  3. Using new battery
  4. Contact service here. 
Red error LED lights up after inserting the battery
  1. Self‐testing errors
  2. Battery failure
  3. Signal memory defective or insufficient free space 
  1. Remove the battery and insert it again.
  2. Using new battery
  3. Empty signal memory
  4. Contact service here. 
Walk Free cannot be initialised after application to the patient
  1. No patient contact
  2. Error recorder module
  3. Bluetooth module not available on PC/tablet, not activated or defective
  1. Read user manual.
  2. Check patient contact, reactivate signal control.
  3. Check Bluetooth interface on PC/tablet.
  4. Contact service here.
No status display during recording (Green LED permanent OFF).  
  1. Battery empty
  2. Error recorder module 
  1. Read ECG.
  2. Change the battery.
  3. Contact service here. 
Red error LED glows while recording. 
  1. Error recorder module
  2. Signal memory defective or insufficient free space
  3. Battery empty
  4. Other error Self‐testing
  1. Read ECG.
  2. Using new battery
  3. Contact service here. 
No Bluetooth connection to Walk Free.  
  1. Bluetooth module on PC, tablet not available, not activated or broken
  2. Error recorder module
  1. Read ECG.
  2. Change the battery.
  3. Check Bluetooth interface on PC/tablet.
  4. Contact service here. 
ECG recording cannot be read.  
  1. Walk Free not connected to Cubeholter
  2. Error recorder module
  1. USB connector check Walk Free (USB cable).
  2. Contact service here.


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