The investigators want to test the accuracy of the Smartphone application Darwin Edge rVSM in measuring heart rate, as compared to traditional pulsoxymetry. The intervention is to look at the smartphone camera for approximately 30 seconds, and after that to compare the heart rate value with that obtained with a recording by pulsoxymetry.

Participants undergoing a routine perianesthetic consultation at the preanesthetic clinic will be recruited. as a part of routine clinical assessment their heart rate is measured with pulsoxymetry, a non invasive device worn at the fingertip for about 1 minute. this measurement will be compared to the values for heart rate that can be obtaine with the ''Darwin Edge rVSM'' mobile application. this application can be installed on any smartphone. the participant is required to look into the smartphone camera for about 30 seconds. environmental and lighning conditions will be kept stable.

The investigators will do the measurements in 200 participants in order to obtaine values in a population characterized by a variety of phenotypes, in the perioperative setting.

Inclusion Criteria:

• Men or women older than 18 years old presenting to the preanesthetic assessment clinic of Valais Hospital
• Subjects that have signed the informed consent form

Exclusion criteria:

• subjects with damaged/injured skin at the face
• Subjects unable to remain still for 30 seconds