Comparison of Perfusion Index Monitoring Using a Smartwatch and a Pulse Oximeter

Perfusion index (PI) is one of the many vital signs monitored to assess the clinical status of a patient. PI is determined from the pulsatile part of the plethysmographic curve, with typical values measured on the fingers ranging from 0.02% to 20%. Although PI is a relatively newly measured parameter, it has already found application in many areas of clinical medicine. For example, continuous measurement of the perfusion index has been used to monitor changes in finger blood flow after finger replantation (surgical reattachment of the finger to the patient's body). As the ability to monitor the perfusion index begins to become part of the monitored parameters of smartwatches, this new feature could be used in situations where the use of finger sensors is not appropriate. However, no comparison of perfusion index measurements between smartwatch and pulse oximeter has been made to date.