Childhood Adenotonsillectomy Trial

3.2 Procedural Guidelines

3.2.1 Arm Measurement

The proper cuff size must be used to avoid under- or over-estimating the correct BP. To determine the proper cuff size, the observer must measure the arm circumference at the midpoint of the arm. This measurement is taken on the left arm that has been bared from the shoulder. Holding the forearm horizontal, the arm length is measured from the acromion (or bony extremity of the shoulder girdle) to the olecranon (or tip of the elbow), with a metric tape, allowing the tape to hang freely. The midpoint is marked on the dorsal surface. The participant should then relax the arm along the side of the body. The arm circumference is measured by drawing the tape snugly around the arm at the level of the midpoint marking. Care must be taken to keep the tape horizontal. Also, the tape should not indent the skin. The chart of arm circumference measurements and corresponding cuff sizes is listed in section 2 and should be utilized as a reference. (A copy of this chart should also be attached to the sphygmomanometer for easy reference.) If the proper cuff size is wider than the length of the arm, use the next smaller cuff in order to get the most reliable readings. This chart should be consulted for each arm measurement. The markings found on most BP cuffs should not be used for reference, as they may be incorrect. Record the proper cuff size in the participant’s source document.

After the initial determination of proper cuff size, this arm measurement does not need to be carried out at each measurement.