(108 days)
No
The device description and other sections do not mention any AI or ML capabilities. The device appears to be a standard electrical stimulator with adjustable parameters and a compliance timer.
Yes
The device is described as providing "Symptomatic relief of chronic intractable pain," "Adjunctive treatment for the management of post-traumatic or post-surgical pain," and various other therapeutic benefits for muscles. This indicates its use in treating medical conditions or alleviating symptoms, classifying it as a therapeutic device.
No
The device description and intended use outline therapeutic applications (pain relief, muscle stimulation, etc.), not diagnostic functions. It does not mention analyzing patient data to identify a condition or disease.
No
The device description explicitly states it is a "combination EMS and interferential stimulation device which delivers nerve or muscle stimulation by applying an electrical current to electrodes". It describes physical components like output channels, jacks, housing, and a battery pack, indicating it is a hardware device with embedded software, not a software-only medical device.
Based on the provided information, this device is not an IVD (In Vitro Diagnostic).
Here's why:
- IVD Definition: In Vitro Diagnostics are medical devices used to examine specimens taken from the human body, such as blood, urine, or tissue, to provide information for diagnosis, monitoring, or screening.
- Device Function: The Flex-MI device described is an electrical stimulator that applies electrical current to the patient's skin for therapeutic purposes (pain relief, muscle stimulation). It does not analyze any biological specimens.
- Intended Use: The intended uses listed are all related to direct patient treatment and symptom management, not laboratory analysis of samples.
Therefore, the Flex-MI falls under the category of a therapeutic medical device, not an In Vitro Diagnostic device.
N/A
Intended Use / Indications for Use
Interferential Stimulation
- Symptomatic relief of chronic intractable pain
- Adjunctive treatment for the management of post-traumatic or post-surgical pain
EMS (Electrical Muscle Stimulation)
- Relaxation of muscle spasm
- Increasing local blood circulation
- Muscle re-education
- Prevention or retardation of disuse atrophy
- Prevention of venous thrombosis of the calf muscles immediately after surgery
- Maintaining or increase range of motion
Product codes (comma separated list FDA assigned to the subject device)
IPF, LIH
Device Description
The Flex-MI is a combination EMS and interferential stimulation device which delivers nerve or muscle stimulation by applying an electrical current to electrodes, which are attached on the patient's skin. The output and waveform is adjustable according to the intended treatment of patient. The stimulator has 2 output channels, accessed through jacks at the top of the housing, so that it may stimulate either 2 or 4 patient electrodes. The device is powered by 4.8V Ni- MH rechargeable battery pack. A patient compliance timer can memorize 60 sets of operation records; the total recordable time is 999 hours. Flex-MI is compatible and recommended for use with Everlife self-adhesive electrodes (K012463).
Mentions image processing
Not Found
Mentions AI, DNN, or ML
Not Found
Input Imaging Modality
Not Found
Anatomical Site
Not Found
Indicated Patient Age Range
Not Found
Intended User / Care Setting
Prescription Use (Part 21 CFR 801 Subpart D)
Description of the training set, sample size, data source, and annotation protocol
Not Found
Description of the test set, sample size, data source, and annotation protocol
Not Found
Summary of Performance Studies (study type, sample size, AUC, MRMC, standalone performance, key results)
Clinical data is not required to support the substantial equivalence to the predicate devices.
Key Metrics (Sensitivity, Specificity, PPV, NPV, etc.)
Not Found
Predicate Device(s): If the device was cleared using the 510(k) pathway, identify the Predicate Device(s) K/DEN number used to claim substantial equivalence and list them here in a comma separated list exactly as they appear in the text. List the primary predicate first in the list.
K112348 RS-4I Plus
Reference Device(s): Identify the Reference Device(s) K/DEN number and list them here in a comma separated list exactly as they appear in the text.
K140467 Flex MT Plus, K071869 Flex IT (TENS/IF 14)
Predetermined Change Control Plan (PCCP) - All Relevant Information for the subject device only (e.g. presence / absence, what scope was granted / cleared under the PCCP, any restrictions, etc).
Not Found
§ 890.5850 Powered muscle stimulator.
(a)
Identification. A powered muscle stimulator is an electrically powered device intended for medical purposes that repeatedly contracts muscles by passing electrical currents through electrodes contacting the affected body area.(b)
Classification. Class II (performance standards).
0
Image /page/0/Picture/0 description: The image contains the logo of the U.S. Food and Drug Administration (FDA). On the left is the Department of Health & Human Services logo. To the right of that is the FDA logo, which is a blue square with the letters "FDA" in white. To the right of the blue square is the text "U.S. FOOD & DRUG ADMINISTRATION" in blue.
10/21/2022
EMSI, Inc. % Cherita James Regulatory Consultant M Squared Associates,Inc. 127 West 30th Street. 9th Floor New York, New York 10001
Re: K221958
Trade/Device Name: Flex-MI Regulation Number: 21 CFR 890.5850, 21 CFR 882.5890 Regulation Name: Powered muscle stimulator Regulatory Class: Class II Product Code: IPF, LIH Dated: October 10, 2022 Received: October 11, 2022
Dear Cherita James:
We have reviewed your Section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database located at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.
If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.
Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part
1
801); medical device reporting of medical device-related adverse events) (21 CFR 803) for devices or postmarketing safety reporting (21 CFR 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reportingcombination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR 1000-1050.
Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR Part 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-device-safety/medical-device-reportingmdr-how-report-medical-device-problems.
For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medicaldevices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-device-advice-comprehensive-regulatoryassistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email (DICE@fda.hhs.gov) or phone (1-800-638-2041 or 301-796-7100).
Sincerely,
For:
CDR Jitendra Virani, Assistant Director DHT5B: Division of Neuromodulation and Physical Medicine Devices OHT5: Office of Neurological and Physical Medicine Devices Office of Product Evaluation and Quality Center for Devices and Radiological Health
Enclosure
2
Indications for Use
510(k) Number (if known) K221958
Device Name Flex-MI
Indications for Use (Describe)
Interferential Stimulation
-
Symptomatic relief of chronic intractable pain
-
Adjunctive treatment for the management of post-traumatic or post-surgical pain
EMS (Electrical Muscle Stimulation)
-
Relaxation of muscle spasm
-
Increasing local blood circulation
-
Muscle re-education
-
Prevention or retardation of disuse atrophy
-
Prevention of venous thrombosis of the calf muscles immediately after surgery
-
Maintaining or increase range of motion
| Type of Use (Select one or both, as applicable) |
|---|
| ------------------------------------------------- |
X Prescription Use (Part 21 CFR 801 Subpart D)
Over-The-Counter Use (21 CFR 801 Subpart C)
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3
510(K) SUMMARY
The following information is provided as required by 21 CFR § 807.87 for the Flex-MI 510(k) premarket notification. In response to the Safe Medical Devices Act of 1990, the following is a summary of the information upon which the substantial equivalence determination is based.
- Sponsor: EMSI, Inc 3504 Cragmont Dr. Suite#100 Tampa, Florida 33619 Telephone: 813-471-0129 Fax: 813-471-0130 Registration Number: 3003573572
- Cherita James Contact: M Squared Associates, Inc. 127 West 30th St, 9th Floor New York, New York 10001 Ph. 347-954-0624 Fax. 703-562-9797 Email: Cjames@MSquaredAssociates.com
Date of Submission: October 10, 2022
Proprietary Name: Flex- MI
Common Name: Combination EMS/Interferential stimulator
Regulatory Class: II
Regulation: 21 CFR 890.5850, 21 CFR 882.5890
Product Codes: IPF Powered Muscle Stimulator, LIH Interferential Current Therapy
Predicate Device(s): K112348 RS-4I Plus
Reference devices: K140467 Flex MT Plus, K071869 Flex IT (TENS/IF 14)
Device Description: The Flex-MI is a combination EMS and interferential stimulation device which delivers nerve or muscle stimulation by applying an electrical current to electrodes, which are attached on the patient's skin. The output and waveform is adjustable according to the intended treatment of patient. The stimulator has 2 output channels, accessed through jacks at the top of the housing, so that it may stimulate either 2 or 4 patient electrodes. The device is powered by 4.8V Ni- MH rechargeable battery pack. A patient compliance timer can memorize 60 sets of operation records; the total recordable time is
EMSI Inc
4
999 hours. Flex-MI is compatible and recommended for use with Everlife self-adhesive electrodes (K012463).
Indications for Use
Interferential Stimulation
-
Symptomatic relief of chronic intractable pain
-
Adjunctive treatment for the management of post-traumatic or post-surgical pain
EMS
-
Relaxation of muscle spasm
-
Increasing local blood circulation
-
Muscle re-education
-
Prevention or retardation of disuse atrophy
-
Prevention of venous thrombosis of the calf muscles immediately after surgery
-
Maintaining or increase range of motion
Substantial Equivalence and Comparison to Predicate Devices
The claim of substantial equivalence of the Flex-MI combination EMS and interferential (IF) stimulator to the like modes of the products identified above is based on the comparison of the indications and intended use, product technical characteristics, performance characteristics and product handling. All devices are for prescription use.
Both the subject device, predicate device and the reference devices have the same indications and intended use for the IF and EMS modes. The primary predicate includes a more broad statement for IF, however the IF indications for the subject device are in-line with most IF devices cleared by the Agency as well as the reference IF device i.e. relief of acute and chronic pain. All devices are prescription devices and the appropriate treatment modality is the responsibility of the prescribing clinician. Based on the comparison in the following table the Flex-MI is substantial equivalent to the predicate device.
5
| | Subject Device
Flex-MI
K221958 | Primary
RS-4I Plus K112348 | Reference K140467
Flex MT Plus (EMS
function) | Reference K071869
Flex IT (IF function) |
|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------|
| Product code | IPF, LIH | IPF, LIH | IPF | LIH |
| Indication for Use | IF- •Symptomatic
relief of chronic
intractable pain
•Post traumatic and
post surgical pain
relief
EMS- Electrical
Muscle Stimulation
•Relaxation of muscle
spasm
•Increasing local
blood circulation
•Muscle re-education
•Prevention or
retardation of disuse
atrophy
•Prevention of
venous thrombosis of
the calf muscles
immediately after
surgery
•Maintaining or
increase range of
motion | IF-
-Relieve acute pain
-Relieve and manage
chronic pain
EMS- Electrical
Muscle Stimulation
•Relaxation of muscle
spasm
•Increasing local blood
circulation
•Muscle re-education
•Prevention or
retardation of disuse
atrophy
•Prevention of venous
thrombosis of the calf
muscles immediately
after surgery
•Maintaining or
increase range of
motion | EMS- Electrical
Muscle Stimulation
•Relaxation of muscle
spasm
•Increasing local blood
circulation
•Muscle re-education
•Prevention or
retardation of disuse
atrophy
•Prevention of venous
thrombosis of the calf
muscles immediately
after surgery
•Maintaining or
increase range of
motion | IF- •Symptomatic
relief of chronic
intractable pain
• Post traumatic and
post surgical pain
relief |
Both the subject device and the predicate devices are battery powered, handheld devices with similar unit characteristics. Based on the comparison in the following table the Flex-MI is substantial equivalent to the predicate devices.
| | Subject Device
Flex-MI | Primary | Reference | Reference |
|---------------------------------------------------------------------|---------------------------------------------------------------------|------------------------------------------|---------------------------------------------------------------------|----------------------------------------------------------|
| | K221958 | RS-4I Plus | Flex MT Plus
(EMS function) | Flex IT (IF
function) |
| 1. 510(k) Number | Not assigned | K112348 | K140467 | K071869 |
| 2. Device Name,
Model | Flex-MI | RS-4I Plus | Flex MT Plus | Flex IT |
| 3. Manufacturer | EMSI/Everlife | RS Medical | EMSI/Everlife | EMSI/Apex
Medical |
| | Subject Device
Flex-MI | Primary
RS-4I Plus | Reference
Flex MT Plus
(EMS function) | Reference
Flex IT (IF
function) |
| | K221958 | | | |
| 4. Power Source | 500 mAh 4.8V Ni-
MH, rechargeable
battery pack and
charger | Lithium Ion battery
with charger | 700 mAh 4.8V Ni-
MH, rechargeable
battery pack and
charger | four batteries, size
AA, alkaline; or
adapter 6VDC |
| 5. Number of Output
Modes | 2 | 2 | 2 | 2 |
| 6. Number of Output
Channels | 2 | 4 | 2 | 2 |
| – Synchronous or
Alternating
– Method of
Channel Isolation | Synchronous or
Alternating
Transformer | Synchronous or
Alternating
unknown | Synchronous or
Alternating
Transformer | Synchronous
Transformer |
| 7. Regulated Current
or Regulated
Voltage? | Regulated Voltage | Regulated Voltage | Regulated voltage | Regulated voltage |
| 8.
Software/Firmware/
Microprocessor
Control? | Yes | yes | Yes | Yes |
| 9. Automatic
Overload Trip? | Yes | unknown | Yes | No |
| 11. Automatic Shut
Off? | Yes | Yes | Yes | Yes |
| 12. Patient Override
Control? | Yes | Yes | Yes | Yes |
| 13. Indicator Display: | Yes | Yes | Yes | Yes |
| On/Off Status? | Yes | Yes | Yes | Yes |
| Low Battery? | Yes | Yes | Yes | Yes |
| Voltage/Current
Level? | Yes (1-10 bars
displayed) | Yes 1-4 bars | Yes (1-10 bars
displayed) | Yes (1-10 bars
displayed) |
| 4. Timer Range
(minutes) | 5-90 minutes, or
continuous | 0-60 minutes | 5-90 minutes, or
continuous | 5-90 minutes, or
continuous |
| 15. Compliance with
Voluntary Standards? | IEC 60601-1-2 as
applicable | unknown | IEC 60601-1-2 as
applicable | IEC 60601-1-2 as
applicable |
| 16. Compliance with
21 CFR 898? | Yes | unknown | Yes | Yes |
| 17. Weight | 159g (including
battery) | 471g including
battery | 156 g (including
battery) | 140g |
| 18. Dimensions [W x
H x D] | 12cm x 5.4cm x
2.5cm | 3.2"x 8" x1.8" | 12 cm x 5.4cm x
3.3cm | 12 cm x 5.5cm x
2.5cm |
| | Subject Device
Flex-MI | Primary | Reference | Reference |
| | K221958 | RS-4I Plus | Flex MT Plus
(EMS function) | Flex IT (IF
function) |
| 19. Housing
Materials and
Construction | plastic | unknown | plastic | plastic |
6
7
Output Specifications
Both the subject device, predicate and the reference devices have similar output specifications and are within the range of currently marketed devices for the proposed intended uses.
Flex-MI and RS-41 Plus– Primary Predicate
| Output
Characteristics
EMS mode | Subject Device- Flex MI K221958 | | Primary -
RS-41 Plus K112348 | |
|-------------------------------------------|------------------------------------------------------------|------------------------------------------------------------------------|---------------------------------|-------------------------|
| Waveform | Asymmetrical
biphasic | Biphasic symmetrical | Asymmetrical
biphasic | Biphasic
symmetrical |
| Shape | Rectangular | | Rectangular | |
| Maximum Output
Voltage | 43.0V @ 500Ω | 43.0V @ 500Ω | 50V @ 500Ω | 50V @ 500Ω |
| Maximum Output
Current | 86.0mA @ 500Ω | 86.0mA @ 500Ω | 100mA @ 500Ω | 100mA @ 500Ω |
| Pulse Width per
phase | Positive 50-400µsec | | Positive 50-400µsec | |
| Max Phase
Duration
(Positive Phase) | 400µs =0.4ms | 400µs =0.4ms | unknown | unknown |
| Max Phase
Duration
(Negative Phase) | 2900µs =2.9ms | 400µs =0.4ms | 2.6ms | 400µs
=0.4ms |
| Pulse Frequency
Max Duty factor | 2150.2Hz150.2Hz
400µs/(1/150.2Hz)
=0.4ms/6.66ms
= 0.060 | 2
(400µs+400µs)/(1/150
.2Hz)
=0.8ms/6.66ms
= 0.120 | 71Hz | 71Hz |
| Multi-phasic
waveforms | Yes | Yes | Yes | Yes |
| Phase duration | Positive 50-400µsec | Positive 50-400µsec | 421µs
=0.421ms | 421µs
=0.421ms |
8
| Output
Characteristics
EMS mode | Subject Device- Flex MI K221958 | Primary -
RS-4I Plus K112348 | |
|-------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------|---------|
| Net Charge
(µC per pulse) | Positive wave
$86.0mA400\mu s$
$=86.0mA0.4ms$
$= 34.4 @ 500\Omega$
Negative wave
$(-86mA/2)*400\mu s+(-$
$8mA/2)2500\mu s$
$=(-43mA)0.4ms+(-$
$4mA)2.5ms$
$= - 17.2+(-10)$
$= - 27.2 @ 500\Omega$
$34.4+ (-27.2)$
$= 7.2 @ 500\Omega$ | unknown | |
| Maximum Phase
Charge
(μC) | Positive wave
$86.0mA400\mu s$
$=86.0mA0.4ms$
$= 34.4 @ 500\Omega$
Negative wave
$(-86mA/2)400\mu s+(-$
$8mA/2)2500\mu s$
$=(-43mA)0.4ms+(-$
$4mA)2.5ms$
$= - 17.2+(-10)$
$= - 27.2 @ 500\Omega$
$34.4+ (-27.2)$
$= 7.2 @ 500\Omega$ | unknown | |
| Surface Area of
Electrode | $4cm4cm= 16cm^2$ | unknown | |
| Maximum Current
Density
(mA/cm²) | $28.1mA/16cm^2$
$= 1.76 @500\Omega$ | unknown | |
| Maximum Power
Density
(W/cm²) | Average Voltage
$43.0V0.4ms/6.66ms$
$= 2.58V @ 500\Omega$
Average Current
$86.0mA0.4ms/6.66m$
s
$= 5.17mA @ 500\Omega$
$2.58V5.17mA/16cm^2$
$=2.58V0.00517A/16$
$cm^2$
$= 0.000834 @500\Omega$ | unknown | |
| Output
Characteristics
EMS mode | Subject Device- Flex MI K221958 | Primary -
RS-4I Plus K112348 | |
| Maximum
Pulse Duration | 400μs+2900μs
=0.4ms+2.9ms
=3.3ms | 400μs+400μs
=0.4ms+0.4ms
=0.8ms | unknown |
| Additional
Features
(if applicable) | Patient compliance timer | Patient compliance timer | |
9
Flex-MI and Flex MT Plus (EMS function)- Reference device
| Output
Characteristics
EMS mode | Subject Device- Flex MI K221958 | | Flex-MT +
K140467 | |
|-------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Waveform | Asymmetrical
biphasic | Biphasic
symmetrical | Asymmetrical
biphasic | Biphasic symmetrical |
| Shape | Rectangular | | Rectangular | |
| Maximum Output
Voltage | 43.0V @ 500Ω
107V @ 2kΩ
214V @ 10kΩ | 43.0V @ 500Ω
105V @ 2kΩ
214V @ 10kΩ | 43.2V @ 500Ω
150V @ 2kΩ
428V @ 10kΩ | 43.2V @ 500Ω
90V @ 2kΩ
344V @ 10kΩ |
| Maximum Output
Current | 86.0mA @ 500Ω
53.5mA @ 2kΩ
21.4mA @ 10kΩ | 86.0mA @ 500Ω
52.5mA @ 2kΩ
21.4mA @ 10kΩ | 86.4mA @ 500Ω
75.0mA @ 2kΩ
42.8mA @ 10kΩ | 86.4mA @ 500Ω
45.0mA @ 2kΩ
34.4mA @ 10kΩ |
| Pulse Width per
phase | Positive 50-400µsec | | Positive 50-400µsec | |
| Max Phase
Duration
(Positive Phase) | 400µs =0.4ms | 400µs =0.4ms | 400µs
=0.4ms | 400µs
=0.4ms |
| Max Phase
Duration
(Negative Phase) | 2900µs =2.9ms | 400µs =0.4ms | 2.6ms | 400µs
=0.4ms |
| Pulse Frequency | 2150.2Hz | 2150.2Hz | 2-151.5Hz | 2-151.5Hz |
| Max Duty factor | 400µs/(1/150.2Hz)
=0.4ms/6.66ms
= 0.060 | (400µs+400µs)/(1/
150.2Hz)
=0.8ms/6.66ms
= 0.120 | 400µsec/6.6ms
= 0.061 | 400µsec+400µsec
/6.6ms
= 0.121 |
| Multi-phasic
waveforms | Yes | Yes | Yes | Yes |
| Output
Characteristics
EMS mode | Subject Device- Flex MI K221958 | Flex-MT +
K140467 | | |
| Phase duration | Positive 50-
400µsec | Positive 50-
400µsec | Positive 50-400µsec | |
| Net Charge
(µC per pulse) | Positive wave
$86.0mA400\mu s = 86.0mA0.4ms = 34.4 @ 500\Omega$
Negative wave
(-
$86mA/2400\mu s + -8mA/22500\mu s = -43mA0.4ms + -4mA2.5ms = -17.2 + -10 = -27.2 @ 500\Omega$
$34.4 + -27.2 = 7.2 @ 500\Omega$ | Positive wave
$86.0mA400\mu s = 86.0mA0.4ms = 34.4 @ 500\Omega$
Negative wave
$-86.0mA400\mu s = -86.0mA0.4ms = -34.4 @ 500\Omega$
$34.4 + -34.4 = 0 @ 500\Omega$ | Positive wave
$86.4mA400\mu sec = 34.6 @ 500\Omega$
Negative wave
$86.4mA400\mu sec = -34.6 @ 500\Omega$
$34.6 + -34.6 = 0 @ 500\Omega$
(symmetrical phases
result in 0) | |
| Maximum Phase
Charge
(µC) | Positive wave
$86.0mA400\mu s = 86.0mA0.4ms = 34.4 @ 500\Omega$
Negative wave
(-
$86mA/2400\mu s + -8mA/22500\mu s = -43mA0.4ms + -4mA2.5ms = -17.2 + -10 = -27.2 @ 500\Omega$
$34.4 + -27.2 = 7.2 @ 500\Omega$ | Positive wave
$86.0mA400\mu s = 34.4 @ 500\Omega$
Negative wave
$-86.0mA400\mu s = -34.4 @ 500\Omega$
$34.4 + -34.4 = 0 @ 500\Omega$ | Positive wave
$86.4mA400\mu sec = 34.6 @ 500\Omega$
Negative wave
$86.4mA400\mu sec = -34.6 @ 500\Omega$
$34.6 + -34.6 = 0 @ 500\Omega$
(symmetrical phases
result in 0) | |
| Surface Area of
Electrode | $4cm4cm= 16cm^2$ | $4cm4cm (1.5in x 1.5in)= 16cm^2$ | | |
| Maximum Current
Density
(mA/cm²) | $28.1mA/16cm^2 = 1.76 @ 500\Omega$ | $42.8mA/16cm^2 = 2.68 @ 500\Omega$ | $29.2mA/44cm^2 = 1.83 @ 500\Omega$
(4cm4cm
Electrode) | |
| Output
Characteristics
EMS mode | Subject Device- Flex MI K221958 | | Flex-MT +
K140467 | |
| Maximum Power
Density
(W/cm²) | Average Voltage
$43.0V0.4ms/6.66 ms = 2.58V @ 500Ω$
Average Current
$86.0mA0.4ms/6.66ms = 5.17mA @ 500Ω$
$2.58V5.17mA/16 cm² =2.58V0.00517A/16cm² = 0.000834 @500Ω$ | Average Voltage
$43.0V0.4ms/6.66 ms = 2.58V @ 500Ω$
Average Current
$86.0mA0.4ms/6.66ms = 5.17mA @ 500Ω$
$2.58V5.17mA/16 cm² =2.58V0.00517A/16cm² = 0.000834 @500Ω$ | Average Voltage
$43.2V0.4ms/6.6ms = 2.62V @ 500Ω$
Average Current
$86.4mA0.4ms/6.6 ms = 5.24mA @ 500Ω$
$2.62V5.24mA/44 cm² = 0.000858@500Ω$
(4cm4cm electrode) | Average Voltage
$43.2V0.4ms/6.6ms = 2.62V @ 500Ω$
Average Current
$86.4mA0.4ms/6.6ms = 5.24mA @ 500Ω$
$2.62V5.24mA/44cm² = 0.000858@500Ω$
(4cm4cm electrode) |
| Maximum
Pulse Duration | $400μs+2900μs =0.4ms+2.9ms =3.3ms$ | $400μs+400μs =0.4ms+0.4ms =0.8ms$ | $400μs+2.6ms =0.4ms+2.6ms =3.0ms$ | $400μs+400μs =800μs =0.8ms$ |
| Additional
Features
(if applicable) | Patient compliance timer | | Patient compliance timer | |
10
11
Flex-MI and Flex IT (Interferential Function)- Reference device
12
| Output Characteristics- IF mode | Subject Device- Flex MI
K221958 | K071869 Flex IT (IF function) |
|----------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------|
| Waveform | Square Wave | Square Wave |
| Shape | Rectangular | Rectangular |
| Maximum Output Voltage | 16.5V@500 Ω
27V@2kΩ
54.6 V@10 kΩ | 15 V @ 500 Ω
24 V @ 2 k Ω
28 V @ 10 k Ω |
| Maximum Output Current | 33mA@500Ω
13.5mA@2kΩ
5.5mA @10kΩ | 30 mA@ 500 Ω
12 mA @ 2 kΩ
2.8 mA @10 k Ω |
| INF: Beat Frequency | -188Hz to +387 Hz, max | -188 to + 387 Hz, max. |
| Pulse Width per phase | 125µs | 125 µs |
| Max Phase Duration
(Positive Phase) | 125µs = 0.125ms | 125µs = 0.125ms |
| Max Phase Duration
(Negative Phase) | 125µs = 0.125ms | 125µs = 0.125ms |
| Pulse Frequency | 4,000Hz | 4,000 Hz |
| Max Duty factor | | |
| Multi-phasic waveforms | Yes | Yes |
| Phase duration | 125 µs=0.125ms | 125 µs |
| Net Charge
(µC per pulse) | Positive wave
$33mA125µs$
$=33mA0.125ms$
$= 4.125@ 500Ω$
Negative wave
$(-33mA)*125µs$
$=(-33mA)*0.125ms$
$=(-4.125)@ 500Ω$
$4.125+ (-4.125)$
$= 0 @ 500Ω$ | $0@ 500Ω$
Symmetrical + and - halves |
| Maximum Phase Charge
(μC) | Positive wave
$33mA125μs =33mA0.125ms = 4.125 @ 500Ω$
Negative wave
$(-33mA)125µsec =(-33mA)0.125ms = (-4.125) @ 500Ω$
$4.125+(-4.125) = 0 @ 500Ω$ | $3 @ 500Ω$ |
| Surface Area of Electrode | $4cm4cm = 16cm^2$ | $1.5 inches1.5inches=2.25in^2$ |
| Maximum Current Density
(mA/cm²) | $33mA(@500Ω)/16cm^2 = 2.06 @ 500Ω$ | $2.08 @ 500Ω$ 1.5 in electrode |
| Maximum Power Density
(W/cm²) | Average Voltage
$16.5V125μs/(1/4000Hz) =16.5V0.125ms/0.25ms = 8.25V @ 500Ω$
Average Current
$33mA125µs/(1/4000Hz) =33mA0.125ms/0.25ms = 16.5mA @ 500Ω$
$8.25V16.5mA/16cm^2 =8.25V0.0165A/16cm^2 = 0.009 @ 500Ω$ | $0.031 @ 500Ω$ |
| Maximum
Pulse Duration | 125 μs | 125 μs |
| Additional Features
(if applicable) | Patient compliance monitor | Patient compliance monitor |
13
Compliance with Standards
The Flex-MI was designed and tested to conform with the following FDA-recognized standards:
| Standard | Recognition
Number |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------|
| IEC 62366-1 Edition 1.0 2015-02
Medical devices - Part 1: Application of usability engineering to medical devices
[Including CORRIGENDUM 1 (2016)] | 5-114 |
| ISO 14971 Third Edition 2019-12
Medical devices - Application of risk management to medical devices | 5-125 |
| ANSI AAMI ES60601-1:2005/(R)2012 and A1:2012, C1:2009/(R)2012 and
A2:2010/(R)2012 Medical electrical equipment - Part 1: General requirements for basic
safety and essential performance (IEC 60601-1:2005, MOD) | 19-4 |
| IEC 60601-1-11 Edition 2.0 2015-01 Medical electrical equipment - Part 1-11: General
requirements for basic safety and essential performance - Collateral Standard: | 19-14 |
14
| Standard | Recognition
Number |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------|
| Requirements for medical electrical equipment and medical electrical systems used in the
home healthcare environment. | |
| IEC 60601-2-10 Edition 2.1 2016-04 Medical electrical equipment - Part 2-10: Particular
requirements for the basic safety and essential performance of nerve and muscle
stimulators | 17-16 |
| IEC 60601-1-2, Medical Electrical Equipment, Part 1: General Requirements for Safety.
Collateral Standard: Electromagnetic Compatibility- Requirements and Test. | 19-8 |
Clinical Data: Clinical data is not required to support the substantial equivalence to the predicate devices.
Conclusion: Based on the Flex-MI and the predicate device's technical characteristics, performance, and indications for use, the subject device is substantially equivalent to the predicate device. The subject device performs as intended for the same indications as the predicate devices with regard to EMS and IF functions.