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 measurement of SpO2 in the 70-100% range has been clinically validated on healthy adult volunteers, at rest, against a laboratory co-oximeter.
• 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.