Alar SpO2 Sensor Study

Inclusion Criteria: * Age 18 or older * Standard of care for planned abdominal surgery foresees continuous SpO2 monitoring intra- and post-operatively * Standard of care for planned abdominal surgery foresees arterial catheterization in order to aspirate blood for blood gas analysis * Expected overnight stay in the peri-operative unit * Able to speak and understand Swedish * Willing and able to provide written informed consent Exclusion Criteria: * Body weight below 50 kg * Procedures and/or conditions affecting the face or hands that might prevent placement of sensors * Injury/wounds or physical malformation of sensor application sites (i.e. nose, fingers) * Severe contact allergies to standard adhesives, latex or other materials found in pulse oximetry sensors (self-reported) * Nail fungus on application site * Refusal to remove artificial nails or nail polish * Severe dermatitis or hyperkeratosis (e.g. ichthyosis) at sensor application site * Raynaud's disease * Hemoglobinopathy * Expected post operative ward stay ≤12 hrs * Dye injections within 48 hours * Pregnant or lactating during the study period * Nasal intubation * Patient is participating in another medical device study.