The mercury manometer is considered the gold standard and the most accurate, but it may not be available because of state regulations or expense. This device needs to be checked regularly to ensure that the reservoir is full, the meniscus is at the zero mark, and the column moves freely when pressure is applied. The filter, vent, and glass column should be cleaned annually. The aneroid manometer is not as accurate as the mercury device and should be compared to a mercury manometer using a Y-tube connector every 6 months. This device needs to be recalibrated when readings differ by more than 3 mm Hg.
Measurement errors pertaining to the cuff usually occur when an inappropriate cuff size is used.
A pediatric cuff is used when the MAC is less than 26 cm. A regular adult cuff covers a MAC of 26 to 32.9 cm. A large adult cuff is used for a MAC between 33 and 40.9 cm, and a thigh cuff covers an area between 41 and 52 cm. For a MAC measurement greater than 52 cm, measure BP in the forearm. For children, have pediatric cuffs of three different sizes available and a Doppler ultrasound stethoscope for infants.