12/09/2025
Not all PAT signals are created equal. Here’s a look at why forehead-based monitoring and Somfit analytics give you earlier, cleaner, and more consistent physiologic insights.
Picture #1
Due to the reduced anatomical distance from the lungs and superior perfusion, changes in blood are seen in the forehead more rapidly than traditional finger sampling. Changes in pulse rate, SpO2, and PAT are seen without the circulatory delay commonly seen in fingertip monitoring and are less affected by conditions that reduce signal quality such as poor perfusion, motion, and temperature changes. Hypoxemia can be detected up to 90 seconds earlier than finger sampling. (Russell, M., 2004) Here we have removed the marked events to better see the changes in blood volume.
Picture #2
Somfit uses a convolution neural network to auto score PAT events. Proven 89 percent accurate to simultaneous in-lab PSG in a peer reviewed study published in the journal Sleep and Biological Rhythms. (McMahon, M., 2025) Here we can clearly see the PAT events marked in concordance with the previous slide showing a reduction in PAT waveform peak and nadir, pulse rate increases, and desaturations.
Picture #3
Not currently available in the US, the Somfit Pro adds an additional five channels to the Somfit platform, including body position, PTAF, and two RIP belts or one RIP belt and a dual lead EKG. Included here for educational purposes, with marked events turned off, on the same epoch we previously saw we can clearly see the correlation of the PAT changes with the PTAF and thoracic effort.
Picture #4
Not currently available in the US, the Somfit Pro adds an additional five channels to the Somfit platform, including body position, PTAF, and two RIP belts or one RIP belt and a dual lead EKG. Included here for educational purposes, with events turned on we can see the correlation between the PAT respiratory events and the marked airflow events.
Citations
Russell, M. W. (2004). Another Look at the Forehead Sensor. APSF Newsletter, Fall 2004.
McMahon, M., Goldin, J., Kealy, E. et al. Evaluating Somfit’s pulse arterial tonometry for detection of obstructive sleep apnoea. Sleep Biol. Rhythms 23, 145 to 152 (2025).