Arterial blood pressure
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Measurement
History

Hales 1733
Riva-Rocci 1896
Cushing 1901

Direct method

Sites

Procedure

Components

Frequency response <40Hz/<20Hz required
Resonance, damping
Other uses- waveform, temperature, dye, blood sampling
Indirect methods
Mercury/aneroid manometer- palpation, oscillation, auscultation (Korotkoff sounds), Pulse detector, Doppler probe.
Oscillotonometer- two cuffs: inflation, pulse detection
Automatic measuring devices- single cuff for inflation & pulse detection

Indirect methods

Finapress device- cuff around finger, continuous measurement
Continuous arterial tonometry- continuous, pressure transducer over radial artery, its output is proportional to BP, periodic calibration needed.

Details
Direct method
Manometer with cuff
Oscillometry- Most common clinical method
Finapress method
Doppler probe/arterial tonometry

Errors NIBP
Detection of Korotkoff sounds
Cuff size
Zero/calibration errors

Errors IABP
Damping- high resonance and critical damping ideal; bubbles, canula, tap, tubing reduce the natural frequency of the system
Complaint catheter wall- damping
Clots- reduce resonant frequency- damping
Zeroing errors

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