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Disclaimer: Due to health regulations and clearances, some ScanWatch features may not be available or may not have clinical validation in your region. Learn more.

Factors that may degrade the performance of reflectance pulse oximetry and heart rhythm analysis via photoplethysmography include:

  • Bright sunlight
  • Presence of strong electromagnetic fields
  • Failure to apply the device correctly (loose wristband application, not on top of the wrist)
  • Tattoos on the wrist in the region of the optical sensor
  • Excessive motion of the arm, wrist, or fingers
  • Low perfusion caused by ambient temperature below the recommended operation range, or by certain conditions such as Raynaud’s syndrome
  • Significant levels of dysfunctional hemoglobin (carboxyhemoglobin, methemoglobin)
  • Venous pulsations
  • Intravascular dyes such as cardio green or methyl blue
  • Blood-flow restrictions due to arterial catheters, blood pressure cuffs, or infusion lines
  • Hypotension, serious vasoconstriction, serious anemia, or hypothermia
  • Cardiac arrest or shock

Important note

  • The quality of SpO2 measurements is very dependent on the skin’s blood perfusion, which is naturally lower at the wrist than on the finger. As such, SpO2 measurements taken at finger tip can be more accurate than those taken at the wrist. This is especially true in situations where the measurement is taken while moving or under circumstances which contribute to low perfusion, such as low temperature or having an underlying health condition which causes poor circulation.
  • The measurement of SpO2 in the 70-100% range has been clinically validated on healthy adult volunteers, at rest, against a laboratory CO-oximeter. Our clinical study has shown that the ScanWatch's oximeter in accurate within 3 percentage points. For comparison, this figure is around 2 percentage points for most finger tip oximeters.
  • ScanWatch also allows you to follow trends on SpO2 averages over long periods by taking regular measurements as it is more practical, and comfortable, to wear the watch than a finger pulse oximeter. Furthermore, by wearing it at night and activating the Respiratory Scan feature, continuous SpO2 monitoring helps detect SpO2 drops corresponding to breathing disturbances.
  • ScanWatch is intended for use in adults (18 years in Europe and 21 years in the US) and with no restrictions on weight. The oximeter is calibrated in the factory before the sale.
  • SpO2 is calculated over a 30-second window (the value is updated every second).
  • You may have more difficulties to obtain a conclusive SpO2 measurement if you wear a metallic or leather wristband. For best results, we recommend using the fluoroelastomer wristband provided with ScanWatch.
  • All measurements taken manually are medical-grade and acknowledged by doctors.
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