Quality
Quality values are between 0 and 4 (0:very low, 1:low, 2:fair, 3:good, 4:very good)
Sp02 has 3 additional values: 103, 104, 105
1.1 Summary of Quality Index (Q-Index)
The Q-Index has been established to confirm the quality of a given vital parameter (Pulse Rate, SpO2, Respiration Rate) taken by the bracelet, prior to transmission as a measured parameter to the Corsano App & Web Portal.
The Q-Index may vary due to the paDent, including :
- wearing incorrectly the bracelet (ie too loose)
- not wearing the bracelet (outside charging period)
- wearing it whilst going swimming or showering
- wearing it over damaged skin (or taNooed)
- variaDons in skin color
- using cream on the skin
- varying levels paDent movement / moDon
1.2 Explanation of how the Q-Index is calculated
In summary, the Q-Index’s are calculated individually for each Pulse Rate, SpO2, Respiration Rate, whereby the :
- PPG signal is filtered
- Peaks and Valleys are detected
- Determination of good and bad PPG pulses, based on Dme and amplitude parameters -- PWD (Pulse Wave Duration) -- PWA (Pulse Wave Amplitude) -- RT (Rise Time) As such the Q-Index is a function of: -- Ratio of “good” pulses in the last window of measurement -- Standard deviation of the previously calculated values (Pulse Rate, SpO2, Respiration Rate)
The Q-Index has an established range of 0 to 4 to evaluate the quality of the signal to the associated measurement.
| Q-Index | Description | Conditions | Impact |
|---|---|---|---|
| 0 | Very bad quality or no measurement possible | Good PPG pulses in the measurement period < 20% OR Standard deviation in the measurement periodis > 20% | Not transmitted by the Bracelet Firmware |
| 1 | Bad quality | Good PPG pulses in the measurement period > 20% AND Standard deviation in the measurement period > 20% | Transmitted, no Alarms. Informative, not for clinical decision |
| 2 | Fair quality | Good PPG pulses in the measurement period > 20% OR Standard deviation in the measurement period is 10% to 20% | Transmitted |
| 3 | Good quality | Good PPG pulses in the measurement period > 20% OR Standard deviation in the measurement period is 5% to 10% | Transmitted |
| 4 | Very good quality | Good PPG pulses in the measurement period > 20% OR Standard deviation in the measurement period is < 5% | Transmitted |
1.3 Quality and alerts
Quality levels 0 and 1 are intended for informational purposes only and should not be used to trigger medical alerts. Alerts should only be triggered for values with a quality level of 2, 3, or 4.
2.0 Sp02 additional quality indexes
Q=103
Low SpO2 Confidence Alert
We have detected an episode of lower SPO2 data-input quality, which temporarily reduces our confidence in providing an accurate SPO2 measurement. This can be caused by factors such as movement, improper sensor fit, or environmental conditions.
To ensure accurate readings: • Make sure the sensor is snug, but comfortable, slightly away from wrist bone • Remove any jewelry near the bracelet.
If the alert persists, please execute a spot SPO2 measurement in a sedentary position.
Q=104
Motion Alert
Reliable SpO2 values cannot be obtained during motion. Excessive movement interferes with sensor accuracy.
Q=105
Venous Pooling Alert
We’ve detected possible signs of venous pooling. Venous pooling is the physiological condition in which lower oxygenated blood accumulates in the veins, particularly in the arm. This may happen if a patient lies on their arm, such as while lying on their side or if there’s restricted movement.
Venous pooling presents a significant challenge for wrist-worn SpO2 devices in reflective mode due to the anatomical properties of the wrist. The increased influence of venous signals on the reflective light path creates difficulties in isolating arterial pulsations.
Corsano developed a new algorithm to differentiate between arterial and venous signals. If venous pooling is detected, data is discarded.
Q=106
Skin Condition May Affect SpO2 Readings
We have detected potential issues with your SpO2 readings that may be caused by brittle or fragile skin. This can lead to inaccurate oxygen saturation measurements due to poor sensor contact, reduced blood circulation, skin damage or dryness. You may try placing the sensor on the other arm. Avoid placing the sensor over bruises, wounds, or dry patches.Keep your skin hydrated and moisturized.