Choose a site that will restrict the participant’s movements as little as possible. For this reason, it’s a good idea to try the ring or middle finger of the non-dominant hand first. The thumb may also be used, provided the thumb reaches to the end of the sensor. Clean the site with an alcohol wipe, and be sure the site is dry and free of debris before placing the sensor.

Use the image of the finger on top of the sensor to correctly position the participant’s finger. The pad of the finger or thumb should completely cover the detector window in the lower half of the sensor. If the detector window is not covered, the Pronto will not take a reading.
The tip of the finger should reach the end of the sensor, at the vertical finger stop. If the fingernail is long, it may extend and pass over the vertical finger stop. The cord should run straight to the back of the hand. Try to keep the cord as straight as possible to avoid signal interference.

Do not place the sensor on an anatomically disfigured finger or a finger with a tight ring. You may also want to avoid fingers with nail polish or acrylic nails, as this can disrupt the test. However, if the Pronto recognizes that the sensor is connected and takes a reading, you can trust the reading even if the site is less than ideal. A few times a day, check the sensors to make sure they are free of debris and grime. Use an alcohol wipe to clean the sensors when needed.