Fig. 2
From: How to measure blood pressure using an arterial catheter: a systematic 5-step approach
Arterial blood pressure measurement with a pressure transducer and a zero line. The free end of the zero line is attached to the body at the level of the vessel of interest. Before the start of the measurement, a zeroing maneuver is needed to account for the difference in height (i.e., hydrostatic pressure) between the free end of the zero line at the level of the vessel of interest and the transducer. Strictly speaking, this difference in height comprises two hydrostatic pressures (considering their theoretical mathematical signs, i.e., positive or negative): (1) the hydrostatic pressure caused by the height difference between the transducer and the arterial catheter and (2) the hydrostatic pressure caused by the height difference between the vessel of interest and the arterial catheter