Accutorr V Operating Instructions
6 - 19
Appendix
Indirect Blood Pressure Measurements and Associated Errors
6.8
Indirect Blood Pressure Measurements and
Associated Errors
Place the patient in a supine position to obtain true physiological pressure. If the cuff is not at
the patient’s heart level, the pressure values obtained will not reflect the true physiological
pressure. Instead, the readings will be decreased by 1.86 mmHg for every inch (0.73 mmHg
for every centimeter) the cuff is placed above the heart level and increased by 1.86 mmHg
for every inch (0.73 mmHg for every centimeter) the cuff is placed below the heart level. This
effect is due to hydrostatic pressure.
Blood has weight and it is this weight that influences these blood pressure readings. The
value of the weight of blood depends on where the measurement is taken with respect to the
heart. When the patient is supine, on a flat surface, the arm is near enough to the heart level
so no adjustment of the NIBP readings will be necessary.
