Palpation of the radial artery helps determine how high to inflate the cuff. Inflate the cuff 30 mm.Hg above the pressure at which the radial pulse was palpated and disappeared. The range of pressures in which the auscultatory gap occurs is recorded (e.g., "blood pressure 190/94, with an auscultatory gap from 190 to 160").
If sounds are heard immediately after inflation of the cuff and the beginning of listening, the pressure should immediately and completely be released. After 60 second, the cuff may then be reinflated to a point 30 mm.Hg above where the sounds were heard the first time. Reinflation of a partially deflated cuff is uncomfortable for the patient and often yields an inaccurate reading.
If sounds cannot be auscultated because of a weakened arterial pulse, use of a Doppler ultrasonic stethoscope may be possible. This stethoscope allows low-frequency sounds to be heard and is commonly used with adults who have very weak blood pressure and with infants and chidrent.
For the blood pressure reading to be accurate, the environment must be quiet, the equipment should be in good working order, and the cuff must fit correctly on the arm and be at the level of the heart. The gauge needs to be in plain view, not off to the side of the arm. The patient should be lying down or sitting up with both feet flat on the floor(legs not crossed)