During calibration, the user should rest quietly for about five minutes in a seated position where user’s elbow rests on the table, slightly below the level of the heart. The palm should be turned upward, with the hand remaining open and relaxed. The arms back and feet should be supported and in a relaxed position. The legs should remain uncrossed.
Systolic BP – 80 mm Hg to 180 mm Hg, trend ± 30 mm Hg
Diastolic BP – 50 mm Hg to 120 mm Hg, trend ± 20 mm Hg
Arm and back are supported, PPG taken from fingertip, and the finger is at heart level.
The following factors alter Blood Pressure readings significantly for cuff based traditional Blood Pressure devices and/or Maxim’s PPG-based measurement system.
After switching on, the device shows the message “Gently Place Finger”, gently place your finger and keep it at least for 10 seconds.
To obtain an accurate measurement, it is important that the person relaxes quietly in a comfortable chair for at least 5 minutes before a reading is taken. Activities such as exercising, talking, drinking, or eating can affect the systolic BP by 10 mm Hg to 20 mm Hg. (Zheng)
During the measurement, the person should always be seated in a comfortable chair, legs uncrossed, with their back and arm supported. If the person’s back is not supported, the diastolic measurement may be increased by 5 mm Hg to 10 mm Hg. Crossing the legs has shown to raise the systolic Blood Pressure by 2 mm Hg to 8 mm Hg. The positioning of the upper arm below the heart level will also result in higher measurement results, whereas positioning the upper arm above the heart level will result in lower Blood Pressure values. These differences can increase/decrease the systolic Blood Pressure by 2 mm Hg for every inch above/below the heart level. (Perloff; O’Brien; Handler)
Stress or anxiety can cause large elevations in BP. If the BP measurement is taken while the subject is thinking about something that causes tension or stress, the BP levels could significantly increase. (Perloff)
Consumption of tobacco products (cigarettes, cigars, smokeless tobacco), alcohol, or caffeine (sodas, coffee, tea) causes BP levels to spike. Therefore, the subject should refrain from smoking/alcohol/caffeine intake at least 30 minutes before a measurement is taken. (James; Marmot; Groppelli)
Blood Pressure is lower when the bladder is empty. As the bladder gradually fills, BP increases. Studies have shown that systolic BP measurements can increase 10mmHg to 15mmHg when the subject has a full bladder.