- The device must be able to detect inflammation presented on the skin surface for all different skin tones
Justification:-
Skin discoloration is a symptom of reduced blood flow, which is a correlate for DVT.
Specifications:-
1.1) The device correctly identifies presentation of erythema from digital images regardless of skin tone over 85% of the time.3
Verifications:-
1.1) Test the algorithm using a new dataset of skin images and verify that 85% of true positives are identified.
- The device must be able to obtain the patient’s Hemoglobin bound Oxygen Levels.
Justification:-
Systemic O2 levels are related to blood clot formation.
Hemoglobin bound Oxygen accounts for 97% of Systemic Oxygen.
Specifications:-
2.1) Obtains measurement at 1Hz from hospital oximeter.5
Verifications:-
2.1) Find the frequency at which the oximeter is taking measurements to ensure it’s no less than 1Hz.
- The device must accommodate a wide range of sizes to match the user.
Justification:-
A wide range of sizes will allow the device to be worn comfortably as well as prevent the device interfering with DVT assessment.
Specifications:-
3.1) Ankle (Mean ± SD)
Male: 23.5 cm ± 1.5 cm (19.0 – 28.0 cm)
Female: 21.9 cm ± 1.3 cm (18.0 – 25.8 cm)
3.2) Must be able to adjust circumference to accommodate the location’s size
Verifications:-
3.1 & 3.2) Verify that the size of the device will be incrementally changeable to accommodate the desired ranges by measuring the device’s length’s.
- The device must have sufficient battery life to monitor the patient’s stats for long periods of time.
Justification:-
A long battery life will allow for continuous monitoring of patients without disruption.
Specifications:-
4.1) More than 12 hours to allow changing of nurse shifts.
Verifications:-
4.1) Measure power consumption of the device and its constituent parts using a LabView model and/or test the physical parts specifications.
- Device must cause little to no reaction to the skin of the patient.
Justification:-
Reactions to the skin can cause interferences with monitoring results and can change patient DVT detection.
Specifications:-
5.1) The power delivered to the skin from the LEDs is less than 180 mW/cm2 at a rate of 0.2 mJ/cm2.6
5.2) The material used that contacts skin should be compliant with ISO 10993-10:2010(E)7.
Verifications:-
5.1) Measure the power output from the LED’s dedicated device to ensure it remains within desired range.
5.2) Place material on participant skins and check for discoloration, damage, and inflammation.
- The device must be able to alert healthcare workers when DVT risk reaches threshold level set by healthcare workers.
Justification:-
Alerting healthcare workers will allow for preventive measures to be taken and prevent further clot formation and damage to the blood vessels.
Specifications:-
6.1) Trigger alarm within <1s when the threshold is reached.
6.2) SpO2 threshold can be set between 95% and 98% with 1% resolution.
6.3) Erythema threshold can be set between 10-25% of the area of the skin displaying inflammation with 1% resolution.
Verifications:-
6.1) Time the delay between the artificial triggering of the device and the triggering of the alarm.
6.2) Test that the device SpO2 threshold can be altered by a user within the given ranges and resolution.
6.3) Test that the device erythema threshold can be altered by a user within the given ranges and resolution.
- The device must remain comfortable to wear.
Justification:-
User comfortability is important as the user will be wearing the device for long periods of times, at least 12 hours.