Childhood Adenotonsillectomy Trial

3.2.5 Determining the Peak Inflation Level

It is necessary to determine, for each participant, the pressure level to which the cuff is to be inflated for accurate measurement of the systolic pressure. (This is because the cuff pressure at the start of the reading should always exceed the systolic pressure— otherwise the first of the Korotkoff sounds will be missed.) This starting pressure is called the “peak inflation pressure” and is determined as follows: The cuff tubing should be attached to the sphygmomanometer. The cuff should be inflated while the radial pulse is palpated and the mercury column watched closely. When sufficient pressure has been applied, the pulse will no longer be felt. When this pulse disappearance has been detected, the cuff is inflated another 20 mm Hg and then quickly and completely deflated. The observed pulse obliteration pressure is noted and 20 mm Hg are added. This sum is the peak inflation level; the cuff is to be inflated to this level for all readings at this examination.

All readings are made to the nearest even digit. Any reading which appears to fall exactly between markings on the column should be read to the next marking immediately above, i.e., 2, 4, 6, 8, or 0.