Medical Device Classification Rules

A medical treadmill, which is used for physiotherapy, cardiopulmonary rehabilitation, ergometry, cardiopulmonary stress test and diagostics as well as for performance diagnostics is a risk class IIb medical device, either when used as stand alone device in a medical environment or when used in connection with an ECG, EMG, ergospirometry or blood pressure monitoring device.

Medical treadmills are risk class IIb medical devices:

active therapeutic devices and also active devices intended for diagnosis and monitoring.

Based on Regulation (EU) 2017/745 on medical devices (MDR) Article 2, Definitions, (4) "Active Device" means any device, the operation of which depends on a source of energy other than that generated by the human body for that purpose, or by gravity, and which acts by changing the density of or converting that energy.  ... Software shall also be deemed to be an active device.

>> With their very powerful electric motors and drive systems, treadmills are active devices delivering "mechanical energy" ("energy of motion / motional energy") to the human body through the moving running belt of the treadmill, partly to patients incapable of reacting, communicating /or who are without a sense of feeling. The subject/patient is not changing his horizontal position and is passively moved and forced to catch up with the running belt underneath his feet. The subject/patient can also be fixed in safety harnesses (fall prevention system), unweighting systems, various supports or even fixed in and moved with a robotic orthotic system utilizing the treadmill. Some subjects/patients are wearing masks or mouthpieces during VO2max. metabolic exercise tests / measurements.

MDR ANNEX VIII  (6. ACTIVE DEVICES) 6.1. Rule 9

All active therapeutic devices intended to administer or exchange energy are classified as class IIa unless their characteristics are such that they may administer energy to or exchange energy with the human body in a potentially hazardous way, taking account of the nature, the density and site of application of the energy, in which case they are classified as class IIb.

...

>> Since the mechanical energy is powerful and exchanged with the human body also partly with patients incapable of reacting, communicating /or who are without a sense of feeling, it is considered to be in a potentially hazardous way.  Thus the risk class is IIb.

MDR ANNEX VIII  (6. ACTIVE DEVICES) 6.2. Rule 10

Active devices intended for diagnosis and monitoring are classified as class IIa:

....

if they are intended to allow direct diagnosis or monitoring of vital physiological processes, unless they are specifically intended for monitoring of vital physiological parameters and the nature of variations of those parameters is such that it could result in immediate danger to the patient, for instance variations in cardiac performance, respiration, activity of the central nervous system, or they are intended for diagnosis in clinical situations where the patient is in immediate danger, in which cases they are classified as class IIb.

>> Based on Rule 10 the treadmill devices intended for diagnosis and monitoring could be classified in risk class IIa, because treadmills with their software (e.g. also software for remote control of treadmills) are being used to obtain readings of vital physiological signals (e.g. heart rate, ECG in combination with stress tests, etc.) in routine check-ups. See also guidance document MDCG 2021-24 October 2021.
Obtaining vital physiological parameters with treadmills are not in a way for example like in intensive care monitoring (partly 24 hours) or ECG, blood pressure, body temperature, oxygen saturation during operations under general anesthetic. However, also the higher risk classification IIb derived of Rule 9 (mechanical energy in potentially hazardous way) outweighs the risk class IIa and so treadmills remain in risk class IIb. 

Important: The h/p/cosmos treadmills as stand alone devices do not contain and/or perform any diagnosis function, but measure, monitor and display physiological parameters (e.g. Heart Rate and Heart Rate Variability) which then can help and support the medical doctor for analysis purpose.

MDR ANNEX VIII  (6. ACTIVE DEVICES) 6.3. Rule 11

...

Software intended to monitor physiological processes is classified as class IIa, except if it is intended for monitoring of vital physiological parameters, where the nature of variations of those parameters is such that it could result in immediate danger to the patient, in which case it is classified as class IIb.

...

>> Based on Rule 11 the software could be classified in risk class IIa, because treadmills with their software (e.g. also software for remote control of treadmills) are being used to obtain readings of vital physiological signals (e.g. heart rate, ECG in combination with stress tests, etc.) in routine check-ups. See also guidance document MDCG 2021-24 October 2021.
Obtaining vital physiological parameters with treadmills are not in a way for example like in intensive care monitoring (partly 24 hours) or ECG, blood pressure, body temperature, oxygen saturation during operations under general anesthetic. However, also the higher risk classification IIb derived of Rule 9 (mechanical energy in potentially hazardous way) outweighs the risk class IIa and so treadmills remain in risk class IIb.    

Medical treadmills many times are also active measuring devices. Depending on their specifications, performance and configuration they measure the heart rate and/or heart rate variability of the subject/patient. When connected through interface with ECG, ergospirometry, blood pressure monitor or EMG they become a new medical system (e.g. stress test system or cardiopulmonary rehab system) and measure also the ECG, VO2max, breath volumes, blood pressure, muscle activity and various other vital functions.

Treadmills can have a “cardio mode”, where a target heart rate is defined and the speed and elevation (load) is controlled automatically until the subject is in “heart rate steady state”. So the treadmill is delivering mechanical energy to the human body based on the vital function (heart rate) of the subject.

Examples of risk classes:

See Medical Device Coordination Group Document MDCG 2021-24 Guidance on classification of medical devices October 2021: 
https://ec.europa.eu/health/sites/default/files/md_sector/docs/mdcg_2021-24_en.pdf

Analyssis: 

Medical treadmills with power supply can never be in risk class I. Since medical bicycle ergometers (without motor drive) are already in risk class IIa, a medical treadmill with motor power must be at least in the same risk class IIa or even higher like IIb due to the motor power and mechanical energy supplied from the medical device (running belt) to the body. This means a Notified Body will regularly check the technical documentation of the manufacturer, including product testing, certificates, risk management file, usability file, CER clinical evaluation report and PMS Post Market Surveillance.  

Immediate danger and additional potential risks during the intended use are involved because

(1) By definition of the intended use for a treadmill as an active therapeutic device, a treadmill is intended to exchange energy (motion energy) in potentially hazardous way. During various treadmill applications some subjects/patients may even be unable to communicate discomfort or problems and/or may be unable to press the emergency stop button by themselves. This can be for example because the subject/patient is wearing a mask or mouthpiece for VO2max metabolic measurement, the subject/patient is disabled, the subject/patient is fixed to special harnesses, the subject has major physical and/or mental limitations or also because of fatigue. Among others, during normal application and/or also in case of falling, fractures, skin-abrasion, bruises, hematoma, traumatic injuries and cardiovascular disorders or even sudden death (e.g. cardiac arrest) may occur during these applications.

(2) During various applications such as ergometry and cardiopulmonary stress tests as well as performance diagnostics, the intended use is to deliver mechanical energy from the treadmill to the subject/patient. It is the intended use to stress the cardiopulmonary system of the patient to an extremely high level, where for examples heart irregularities or even heart failure occur. This is done under controlled and supervised environment. Medical staff and emergency equipment (defibrillator, ECG, etc.) has to be present at any time. Among others, during normal application and/or also in case of falling, fractures, skin-abrasion, bruises, hematoma, traumatic injuries and cardiovascular disorders or even sudden death (e.g. cardiac arrest) may occur during these applications.

(3) The subject/patient may have problems at any time to catch up with the speed of the moving running belt and therefore is always in the risk of falling. Falling on a treadmill can result in serious injuries (bruises, skin-abrasions, burns, broken bones, etc.).

(4) Malfunction of heart rate measurement or wrong target heart rate settings may result in overload to the subject through too high loads (speed and elevation) and therefore can lead to serious health conditions or even death. 

Some other potential and/or technical risks, which are not related to the intended use:

(5) Danger of electric shock through isolation malfunction of the treadmill or ECG involved increases when the treadmill is linked via interface to ECG and so indirectly linked with electrodes to the skin of the subject. Treadmills are usually powered with single phase 110 … 240 volts or even 3-phase 3x400 Volts.

(6) Malfunction of speed control of the running belt or the interface communication with ECG and ergospirometry device may result in unwanted and immediate acceleration of the running belt.

(7) Dangerous capture zones mainly at the running belt re-entry zone (gap between belt and frame at the rear roller zone) or through other moving parts and frame of the treadmill when using the elevation system, adjustable handrails, unweighting systems, etc.

(8) A number of deadly accidents are known with treadmills. Luckily there are no known deadly accidents or incidents with h/p/cosmos treadmills so far in more than 33 years of history with many thousands of treadmills on the worldwide market due to high quality and high safety standard of h/p/cosmos treadmills and due to great efforts on product training, instruction and compliance with regulatory requirements.

Intended use, specific function, purpose, indications in medical field:

h/p/cosmos medical treadmills are intended for walking or running* in place for

• Recreational fitness training (incl. athletes)
• Gait training (with or without body weight support)

h/p/cosmos medical treadmills can be used in combination with external devices for walking or running* in place as

• Stressing devices for neuromuscular and biomechanical measurements (e.g. EEG, EMG, motion analysis)
• Stressing devices for cardiovascular measurements (e.g. ECG)
• Stressing devices for cardiopulmonary measurements (e.g. ergospirometry)

* Devices marked with an “r” or "rs" like “h/p/cosmos saturn 250/75 r” are intended for applications with wheels as well. Applications with wheels include cycling, roller skiing, wheelchair applications, etc.

The indications, target population and target user groups for treadmill testing and treatment have to be decided by the medical doctor and primarily have to be derived from international accepted guidelines.

Contraindications​

Absolute contraindications (have to be excluded before the treadmill is used)

• Acute myocardial infarction (within 2 days)
• Instable angina pectoris Cardiac arrhythmia pathology and/or limited hemodynamics
• Symptomatic massive aortic stenosis
• Uncompensated / uncontrolled heart insufficiency
• Acute pulmonary embolism or pulmonary infarction
• Acute endocarditis, myocarditis, pericarditis
• Acute aortic dissection Acute coronary syndrome
• Acute phlebothrombosis of the lower extremities
• Febrile infections
• Pregnancy
• Acute thrombosis
• Fresh wounds e.g. after surgery
• Acute fracture
• Damaged disc or traumatic disease of the spine
• Epilepsy
• Inflammations
• Acute migraine
• uncontrolled heart failure
• dissecting aneurysm
• recent aortic surgery and ECG abnormalities, such as abnormal ST-segment response (horizontal, planar or downslopingdepression of >1 mm, T-wave elevation of > 1 mm in leads without Q-waves, and Twavechanges such as inversion and pseudo-normalization when an inverted T-wave becomes upright. Relative contraindications (The application may be started if the possible benefits exceed the risks. The decision has to be made by the medical doctor before the treadmill is used) Left main coronary stenosis Main artery disease Cardiac valve disease of moderate severity Known electrolyte imbalance Arterial hypertonia (RR > 200 mm Hg syst. > 110 mm Hg diast.) Tachyarrhythmia or bradyarrhythmia Hypertrophic cardiomyopathy and other forms of outflow tract obstruction Higher degree atrioventricular AV-blocking Anemia Physical and/or mental disabilities leading to inability to exercise adequately Partially invasive medical devices (probes, infusions, catheters, external fixators, etc.)

Relative contraindications (The application may be started if the possible benefits exceed the risks. The decision has to be made by the medical doctor before the treadmill is used)

• Left main coronary stenosis
• Main artery disease
• Cardiac valve disease of moderate severity
• Known electrolyte imbalance
• Arterial hypertonia (RR > 200 mm Hg syst. > 110 mm Hg diast.)
• Tachyarrhythmia or bradyarrhythmia
• Hypertrophic cardiomyopathy and other forms of outflow tract obstruction
• Higher degree atrioventricular AV-blocking
• Anemia
• Physical and/or mental disabilities leading to inability to exercise adequately
• Partially invasive medical devices (probes, infusions, catheters, external fixators, etc.) 

Due to the risk class IIb quite a number of safety, risk management and regulatory activities have to be performed by all manufacturers of medical treadmills. Among others are:

1. Product design and compliance based on standards such as IEC 60601-1, IEC 60601-1-2, IEC 60601-1-6, ISO 14971, EN 62304, ISO 10993, ISO 20957-1, ISO 20957-6, etc.
   This product design includes (among others) potential isolation transformer, potential equalization pin, two side handrails for user support and emergency dismount, foot rails with min. width of 80 mm, permanent marking on the running surface to determine if the belt is either moving or stationary, and also the warning label based on ISO 20957-6: 
   “WARNING! Heart rate monitoring systems may be inaccurate. Over exercising may result in serious injury or death. If you feel faint stop exercising immediately”.
2. Compliance with EU directives and regulations, such as MDR Medical Device Regulation (EU) 2017/745, Machinery Directive 2006/42/EC, RoHS Directive 2011/65/EU, etc.
3. CE marking of the medical devices with CE and 4-digit number of the involved Notified Body (e.g. CE0123) including EU Declaration of Conformity. A CE mark alone (without 4-digit number) is not sufficient for motor powered medical treadmills and/or medical treadmills with measuring functions. 
4. Registration of manufacturer / distributor in EU EUDAMED database as economic operator with SNR. (h/p/cosmos SRN: DE-MF-000006147)
5. Implementation of UDI System (Unique Device Identification) with Basic UDI-DI, UDI-DI and UDI-PI.   
6. Implementation of the PMS Post Market Surveillance and the European system for the notification and evaluation of INCIDENTs and FIELD SAFETY CORRECTIVE ACTIONS (FSCA) involving MEDICAL DEVICEs, known as the "Medical Device Vigilance System".
7. Annual PSUR Periodic Safety Update Report and Trend Reports to EU Authporities (EUDAMED). 

Clinical studies are not required for treadmills, since:

a) performance data are available and fulfilled based on the norms ISO 20957-1 and ISO 20957-6 for treadmills;

b) treadmills have been used for more than 60 years worldwide and the clinical benefits are well documented. The clinical benefits exceed the involved risks which are arising in the applications. In the risk management system based on ISO 14971 h/p/cosmos has performed benefit-risk assessment and documented the control of all known risks and residual risks.

Among important measures and warnings for risk control for h/p/cosmos medical treadmills are:

• Emergency stop device disconnecting voltage power supply to drive motors and elevation motors without involving software.
• Making it obligatory to use a safety arch with chest belt harness (or alternatively unweighting device) as a fall-stop-prevention for higher-risk applications, where falling would result in an inacceptable risk.
• Implementing structured installation and commissioning protocol cos15228-04 (accompanying document) and training for the treadmill operators.
• Warnings (among others) on device and in manual / IFU Instructions For Use:

1. Heart rate monitoring systems may be inaccurate. 
2. Incorrect or over exercising may result in serious injury or death. 
3. If you feel faint or dizzy stop exercising immediately and consult a medical doctor.
4. Keep children and animals in safe distance of min. 2 m from the device.
5. The intended operator has to be in reach of at least one emergency stop button at any time. (This means that e.g. the therapist or doctor, who operates the medical treadmill, must be close to the treadmill and must not leave the surrounding or the room).

Useful Links:

Medical Device Coordination Group Document MDCG 2021-24 October 2021: Guidance on classification of medical devices: https://ec.europa.eu/health/sites/default/files/md_sector/docs/mdcg_2021-24_en.pdf 

MDR: Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A32017R0745 

This article has been updated Nov. 17, 2021.