Surgery>>>>>Physiologic Monitoring of the Surgical Patient
Question 2#

Of the following parameters, which is the least influenced by an underdamped or overdamped intra-arterial blood pressure monitoring system?

A) Systolic blood pressure
B) Mean arterial blood pressure
C) Diastolic blood pressure
D) Pulse pressure

Correct Answer is B


If the system is underdamped, then the inertia of the system, which is a function of the mass of the fluid in the tubing and the mass of the diaphragm, causes overshoot of the points of maximum positive and negative displacement of the pressure transducer diaphragm during systole and diastole, respectively. Thus, in an underdamped system, systolic pressure will be overestimated and diastolic pressure will be underestimated. In an overdamped system, displacement of the diaphragm fails to track the rapidly changing pressure waveform, and systolic pressure will be underestimated and diastolic pressure will be overestimated. It is important to note that even in an underdamped or overdamped system, mean pressure will be accurately recorded, provided the system has been properly calibrated. For these reasons, when using direct measurement of intra -arterial pressure to monitor patients, clinicians should make clinical decisions based primarily on the measured mean arterial blood pressure.